Composite of metal and resin and method for manufacturing same

Abstract

A magnesium alloy part is inserted into a mold, a resin composition is injected and joined to the part, and a composite is obtained. A part having, formed thereon, a surface layer of a metal oxide, a metal carbonate, or a metal phosphate in use of a usual conversion treatment or a modification method thereof can be used for the magnesium alloy plate 1. The surface that has a larger amount of crystal-like objects of a nanolevel on the surface layer composed of the metal oxide, metal carbonate, or metal phosphate has a higher level of hardness, microscopic roughness, and good injection joining force, and these parameters can be controlled by a conversion treatment method. A resin composition 4, containing PBT or PPS as the main component, is used as the resin composition part.

Claims

1. A method for manufacturing a composite of a metal and a resin, comprising: a shaping step of obtaining a shaped part from a cast article or an intermediate product composed of a magnesium alloy by shaping by mechanical processing; a chemical etching treatment step of forming a surface configuration of the shaped part by immersing the shaped part in an aqueous solution of etching agent, a conversion treatment step of forming one species, selected from a metal oxide, a metal carbonate, and a metal phosphate, on a surface layer of the shaped part after the chemical etching treatment has been performed; an injection step of inserting the shaped part having been subjected to the chemical etching treatment step and the conversion treatment step into a metallic mold for injection molding and injecting a molten resin composition comprising polyphenylene-sulfide as a main component and modified polyolefin resin as an auxiliary component, or polybutylene-terphthalate as a main component and polyethylene-terephthalate as an auxiliary component and a fixing step of introducing and solidifying by the injection molding in concavities of the metal oxide or metal phosphate, and integrally fixing the shaped part and the resin composition; wherein said surface configuration of the shaped part formed through the chemical etching treatment and the conversion treatment is such that spherical formations with a diameter of 80 to 120 nm are aggregated to form periodic irregularities with a period of 0.5 to 1 μm.

2. The method for manufacturing a composite of a metal and a resin according to claim 1, wherein the conversion treatment step is a conversion treatment using an aqueous solution of at least one kind selected from chromium, manganese, vanadium, calcium, zinc, strontium, zirconium, a titanium compound, and an alkali metal carbonate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a structural drawing of an injection molding mold that illustrates schematically the process of manufacturing a composite of a magnesium alloy piece and a resin composition.

(2) FIG. 2 is an external appearance drawing of a schematically illustrated single unit of a composite of a magnesium alloy piece and a resin composition.

(3) FIG. 3 is a surface photograph of an AZ31B magnesium alloy with an average grain size of metal crystals of 7 μm or less that is obtained by using an aqueous solution of acetic acid as a rough etching agent, using dilute nitric acid as a fine etching agent, and performing conversion treatment of a manganese phosphate system.

(4) FIG. 4 is a surface photograph of an AZ31B magnesium alloy with an average grain size of metal crystals of 7 μm or less that is obtained by using an aqueous solution of acetic acid as a rough etching agent, using citric acid as a fine etching agent, and performing conversion treatment of a potassium permanganate system.

(5) FIG. 5 is a surface photograph of an AZ31B magnesium alloy with an average grain size of metal crystals of 7 μm that is obtained by using an aqueous solution of acetic acid as a rough etching agent, using dilute nitric acid as a fine etching agent, and performing conversion treatment of a potassium carbonate system.

(6) FIG. 6 is a surface photograph of an AZ31B magnesium alloy (manufactured by Nippon Kinzoku Kogyo KK, Tokyo, Japan) with an average grain size of metal crystals of 7 μm that has been subjected only to a degreasing treatment.

EXPLANATION OF KEYS

(7) 1 magnesium alloy plate 2 movable mold plate 3 fixed mold plate 4 resin composition 5 ping point gate 6 joining surface 7 composite

BEST MODE FOR CARRYING OUT THE INVENTION

(8) Embodiments of the present invention are explained below based on examples thereof. FIG. 1 and FIG. 2 are used as the drawings shared by the examples. FIG. 1 is a structural diagram of a mold that illustrates schematically an injection molding mold composed of a movable mold plate and a fixed mold plate. FIG. 2 shows an external appearance of a composite 7 in which a base material 1 and a resin composition 4 are fixed integrally by using the injection molding mold.

(9) The magnesium alloy plate 1 processed to a predetermined shape is inserted between the movable mold plate 2 and fixed mold plate 3 of a metallic mold 10 for injection molding, and the molten resin composition 4 is injected from the nozzle and poured into the mold cavity via a pin gate 5. The resin composition 4 is fixed to a joining surface 6 having fine concavities formed on the surface of the magnesium alloy plate 1, and a composite 7 in which the two are integrated is manufactured. In the below-described examples, in order to measure the fixing strength of the composites 7 manufactured in the examples, a tension is applied to the magnesium alloy plate 1 and resin composition 4, the joining surface 6 thereof is loaded with a shear stress, and the rupture strength thereof is measured to check the fixing force.

EXAMPLES

(10) Examples of the present invention will be described below in greater detail. First, evaluation and measurement methods and measurement equipment used for evaluating and measuring composites obtained in the below-described examples will be described.

(11) [Evaluation and Measurement Methods and Measurement Equipment]

(12) (a) Melt Viscosity Measurement of Resin

(13) A high-performance flow tester well known as means for measuring melt viscosity and fluid characteristics of various thermoplastic and thermosetting plastics was used to measure the melt viscosity of resins. The melt viscosity was measured at a measurement temperature of 315° C. and under a load of 0.98 Mpa (10 kgf) with a high-performance flow tester “CFT-500 (product name)” (manufactured by Shimazu Corp., Kyoto prefecture, Japan) equipped with a die with a diameter of 1 mm and a length of 2 mm (b) X-Ray Photoelectron Analyzer (XPS Observations)

(14) As one surface observation method, observation was conducted with a photoelectron analyzer (XPS observations) by which the energy of photoelectrons emitted from a sample when the sample was irradiated with X rays was analyzed and qualitative analysis of elements was performed. An “Axis-Nova (product name)” (manufactured by Kratos Analytical Co., Ltd. (England)/Shimazu Corp.) of a system in which a surface with a diameter of several micrometers is observed within a depth range up to several nanometers was used as the photoelectron analyzer. (c) Electron Microscope Observations

(15) An electron microscope was used mainly for observing the base material surface. A scanning (SEM) electron microscope “5-4800 (product name)” (manufactured by Hitachi, Ltd., Tokyo, Japan) and “JSM-6700F (product name)” (manufactured by Hitachi Denshi KK, Tokyo, Japan) were used as the electron microscopes. The observations were performed at 1 to 2 KV. (d) Scanning Probe Microscope Observations

(16) The aforementioned microscope was mainly used for observing the base material surface. The scanning probe microscope uses a probe with a protruding distal end and the surface stage is enlarged and observed by moving the probe so as to trace the material surface. “SPM-9600 (product name)” (manufactured by Shimazu Corp., Kyoto prefecture, Japan) was used as the scanning probe microscope. (e) Measurement of Joining Strength of Composites

(17) As for the tensile stress, the composite 7 was stretched, a shear force was applied, and a shear force at the time of rupture was taken as a shear stress. “Model 1323 (product name)” (manufactured by Aiko Engineering KK, Tokyo, Japan) was used as the tensile test machine, and the shear force was measured at a tension rate of 10 mm/min (f) Salt Water Spraying Test

(18) A salt water spraying test was performed to test the composite in accordance with the present invention for corrosion resistance. A salt water spraying test machine “SPT-90” (manufactured by Suga Shikenki KK, Tokyo, Japan) that is a material testing device for testing a material for corrosion resistance and deterioration by spraying salt water was used to perform the test.

Preparation Example 1 of PPS Composition

(19) The PPS Preparation Example 1 represents a preparation example in which PPS and a polyolefin resin were mixed. A total of 6,214 g of Na.sub.2S.2.9H.sub.2O and 17,000 g of N-methyl-2-pyrrolidone were charged into an autoclave having a capacity of 50 L and equipped with a stirrer, and the temperature was gradually raised to 205° C., while stirring under a nitrogen flow, to distill off 1355 g of water. The system was cooled to 140° C., then 7160 g of p-dichlorobenzene and 5000 g of N-methyl-2-pyrrolidone were added and the system was sealed under a nitrogen flow. The temperature of the system was raised to 225° C. within 2 h, and the system was polymerized for 2 h at 225° C. Then, the temperature was raised to 250° C. within 30 min and the polymerization was further continued for 3 h at 250° C.

(20) Upon completion of polymerization, the polymer cooled to room temperature was isolated with a centrifugal separation machine. The solid fraction of the polymer was repeatedly washed with warm water and dried overnight at 100° C. to obtain PPS (referred to hereinbelow as PPS (1)) with a melt viscosity of 280 poise. The PPS (1) was further cured for 3 h at 250° C. under a nitrogen atmosphere to obtain PPS (referred to hereinbelow as PPS (2)). The PPS (2) thus obtained had a melt viscosity of 400 poise.

(21) A total of 6.0 kg of the PPS (2) obtained, 1.5 kg of a terpolymer of ethylene, acrylic acid ester, and maleic anhydride “Bondine TX8030 (product name)” (manufactured by Alchema Co., Kyoto, Kyoto Prefecture, Japan), and 0.5 kg of epoxy resin “Epicoat 1004 (product name)” (manufactured by Japan Epoxy Resin Co., Ltd., Tokyo, Japan) were premixed homogeneously in a tumbler. Then, the mixture was melt kneaded at a cylinder temperature of 300° C. in a twin-screw extruder “TEM-35B (product name)” (manufactured by Toshiba Kiki KK, Shizuoka Prefecture, Japan), while supplying glass fibers “RES03-TP91 (product name)” (manufactured by Nippon Sheet Glass Co., Ltd., Tokyo, Japan) having an average fiber diameter of 9 μm and a fiber length of 3 mm from a side feeder so as to obtain a total added amount of 20 wt. %, thereby producing a pelletized PPS composition (1). The PPS composition (1) is a resin composition in which the polyolefin resin takes 20% of the entire resin fraction, and the epoxy resin fraction takes 7 parts, the entire resin fraction being 100 parts. The PPS composition (1) thus obtained was dried for 5 h at 175° C.

Preparation Example 2 of PPS Composition

(22) The PPS composition (1) obtained in the Preparation Example 1 of a PPS composition was cured for 3 h at a temperature of 250° C. under an oxygen atmosphere to obtain PPS (referred to hereinbelow as PPS (3)). The melt viscosity of the PPS (3) thus obtained was 1800 poise. A total of 5.98 kg of the PPS (3) obtained and 0.02 kg of polyethylene “Nipolon Hard 8300A (product name)” (manufactured by Tosoh Corp., Tokyo, Japan) were premixed homogeneously in a tumbler. Then, the mixture was melt kneaded at a cylinder temperature of 300° C. in the twin-screw extruder “TEM-35B” (above-mentioned), while supplying glass fibers “RES03-TP91” having an average fiber diameter of 9 μm and a fiber length of 3 mm from a side feeder so as to obtain a total added amount of 40 wt. %, thereby producing a pelletized PPS composition (2). This composition is a resin composition in which the polyolefin resin takes 0.3% of the entire resin fraction. The PPS composition (2) thus obtained was dried for 5 h at 175° C.

Preparation Example 3 of PPS Composition

(23) A total of 7.2 kg of the PPS composition (2) obtained in the Preparation Example 1 of a PPS composition and 0.8 kg of glycidyl methacrylate-ethylene copolymer “Bondfast E” (manufactured by Sumitomo Chemical Co., Ltd.) were premixed homogeneously in a tumbler. Then, the mixture was melt kneaded at a cylinder temperature of 300° C. in the twin-screw extruder “TEM-35B” (above-mentioned), while supplying glass fibers “RES03-TP91” having an average fiber diameter of 9 μm and a fiber length of 3 mm from a side feeder so as to obtain a total added amount of 20 wt. %, thereby producing a pelletized PPS composition (3). This composition is a resin composition in which the polyolefin resin takes 10% of the entire resin fraction. The PPS composition (3) thus obtained was dried for 5 h at 175° C.

Preparation Example 4 of PPS Composition

(24) A total of 4.0 kg of PPS (2) obtained in the Preparation Example 1 of a PPS composition and 4.0 kg of a terpolymer of ethylene, acrylic acid ester, and maleic anhydride “Bondine TX8030 (product name)” (manufactured by Alchema Co., Kyoto, Kyoto Prefecture, Japan), were premixed homogeneously in a tumbler. Then, the mixture was melt kneaded at a cylinder temperature of 300° C. in the twin-screw extruder “TEM-35B” (above-mentioned), while supplying glass fibers “RES03-TP91” having an average fiber diameter of 9 μm and a fiber length of 3 mm from a side feeder so as to obtain a total added amount of 20 wt. %, thereby producing a pelletized PPS composition (4). This composition is a resin composition in which the polyolefin resin takes 50% of the entire resin fraction. The PPS composition (4) thus obtained was dried for 5 h at 175° C.

Preparation Example 5 of PBT Composition

(25) A PBT composition (1) containing PBT 47% and glass fibers 38% was obtained by kneading a commercial PBT resin (Toraycon 1101G45 (manufactured by Toray Industries, Inc., Tokyo, Japan) and a PBT resin in use of the twin-screw extruder “TEM-35B”. The PBT composition (1) is a resin composition in which PET takes 24% of the entire resin fraction. The composition thus obtained was dried for 5 h at 130° C.

Example 1

(26) AZ31B magnesium alloy (manufactured by Nippon Kinzoku Kogyo KK, Tokyo, Japan) with a thickness of 0 8 mm and an average metal crystal size on the surface of 7 μm that was subjected to wet buffing as a final surface processing was used. The magnesium alloy sheet was cut to a rectangular shape with dimensions of 18 mm×45 mm (thickness 0.8 mm) to obtain magnesium alloy sheets 1. A through hole was provided in the end portion of the magnesium alloy sheets 1, a copper wire coated with vinyl chloride was passed through ten sheets, the copper wire was bent so that multiple magnesium alloy sheets 1 were not stacked, and all the sheets were hung down at the same time.

(27) A commercial degreasing agent “Cleaner 160 (product name)” (manufactured by Marutekkusu KK, Tokyo, Japan) for magnesium alloys was poured into water in a degreasing tank to obtain an aqueous solution with a concentration of 10% at 75° C. The alloy pieces were immersed therein for 5 min and washed thoroughly with water. Then, a 2% aqueous solution of acetic acid with a temperature of 40° C. was prepared in a separate tank and the alloy pieces were immersed therein for 2 min and washed thoroughly with water. Black smut adhered thereto. A 7.5% aqueous solution of a degreasing agent “NE-6 (product name)” (manufactured Marutekkusu KK, Tokyo, Japan) for aluminum alloys at a temperature of 75° C. was prepared in a separate tank and the magnesium alloy pieces were immersed therein for 5 min and washed thoroughly with water. It was seen that the aluminum fraction of the smut was dissolved by the weak basicity of the liquid. Then, a 20% aqueous solution of caustic soda at 75° C. was prepared in another tank and the aforementioned alloy pieces were immersed therein for 5 min and washed thoroughly with water. It can be assumed that the zinc fraction of the smut was dissolved thereby. A 2% aqueous solution of nitric acid with a temperature of 40° C. was then prepared in a separate tank, and the magnesium alloy pieces were immersed therein for 1.5 min and washed thoroughly with water.

(28) Then, a non-chromate conversion treatment liquid of a manganese phosphate system at 45° C. was prepared in a separate tank. Thus, an aqueous solution containing 2.5% manganese diphosphite, 2.5% phosphoric acid with a concentration of 85%, and 2% triethylamine was prepared, the magnesium alloy pieces were immersed therein for 5 min, washed thoroughly with water, placed for 10 min in a warm air drier at 60° C., and dried. Upon completion of drying, the copper wire was pulled out from the magnesium alloy sheets on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers or the like.

(29) In 2 days, one piece was observed under an electron microscope. A large number of plate-like crystals were seen on the surface, in other portions, amorphous mater was seen. The length of cavities produced by the plate-like crystals was 400 to 600 nm, and the depth thereof was 500 nm or more. The number of the plate-like crystals that could be observed in a square with a side of 1 μm was 1 to 5, the specific number depending on the location. The surface image is shown on an electron micrograph (see FIG. 3). the remaining magnesium alloy sheets 1 were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the sheets were inserted into an injection molding mold at 140° C. The mold was closed, a PBT resin composition “Toughpet G1030 (product name)” (manufactured by Mitsubishi Rayon Co., Ltd.) containing 30% glass fibers was injected at an injection temperature of 260° C. The mold temperature was 140° C., and a total of 20 integrated composites shown in FIG. 2 were obtained. The resin portion had the dimensions of 10 mm×45 mm×5 mm, and the joint surface 6 had the dimensions of 10 mm×5 mm and a surface area of 0.5 cm.sup.2.

(30) Four composites were subjected to a tensile rupture test on the molding day, and the average shear force was 11.8 MPa. Further, five composites were placed for 1 h into a hot air drier at a temperature of 150° C. on the molding day and annealed, followed by a tensile test conducted one day after. The average shear rupture stress was 11.9 MPa. The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” (manufactured by Ohashi Chemical Industries Co., Ltd., Osaka, Japan) to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h at normal temperature by using 1% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Example 2

(31) An AZ31B alloy sheet with a thickness of 0.8 mm that had an average metal crystal grain size of 7 μm was procured. The sheet was cut in the same manner as in Example 1 to obtain rectangular pieces that were immersed for 5 min in an aqueous solution of the degreasing agent “Cleaner 160” with a concentration of 10% at 75° C. and washed thoroughly with water. A 2% aqueous solution of acetic acid at 40° C. was then prepared in a separate tank, and the aforementioned magnesium alloy sheets 1 were immersed therein for 2 min and washed thoroughly with water. Black smut adhered thereto. A 7.5% aqueous solution of a degreasing agent “NE-6 (product name)” (manufactured Marutekkusu KK, Tokyo, Japan) for aluminum alloys at a temperature of 75° C. was prepared in a separate tank and the magnesium alloy pieces were immersed therein for 5 min and washed thoroughly with water. Then, a 20% aqueous solution of caustic soda at 75° C. was prepared in another tank and the group of magnesium alloy sheets 1 were immersed therein for 5 min and washed thoroughly with water. The above-described treatment was pretreatment, and the treatment method was identical to that of Example 1.

(32) Then, the pieces were immersed for 15 sec in an aqueous solution of citric acid with a concentration of 0.5% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. An aqueous solution containing 3% potassium permanganate, 1% acetic acid, and 0.5% sodium acetate at 45° C. was then prepared, and the pieces were immersed therein for 1 min, followed by thorough washing with water. The pieces were colored brown and were apparently covered with manganese dioxide. The pieces were then introduced for 10 min into a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy sheets 1 on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers or the like.

(33) In 2 days, one piece was observed under an electron microscope. Spherical formations with a diameter of 80 to 120 nm that were produced by fine needle crystals were assembled, and these formations aggregated and joined together, producing periodic concavities and convexities. The period of 0.5 to 1 μm and the depth of concavities was 0.3 to 1 μm. The number of spherical formations per one square with a side of 1 μm was 90 to 120. The micrograph is shown in FIG. 4. The remaining magnesium alloy sheets 1 were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the sheets were inserted into an injection molding mold at 140° C. A total of 10 integrated composites shown in FIG. 2 were obtained in the same manner as in Example 1. The composites were placed for 1 h into a hot air drier at a temperature of 150° C. on the molding day and annealed, followed by a tensile test conducted one day after. The average shear force was 11.6 MPa.

Example 3

(34) An AZ31 alloy sheet with a thickness of 0.8 mm that had an average metal crystal grain size of 7 μm was procured. The sheet was cut in the same manner as in Example 1 to obtain rectangular pieces that were immersed for 5 min in an aqueous solution of the degreasing agent “Cleaner 160” with a concentration of 10% at 75° C. and washed thoroughly with water. A 2% aqueous solution of acetic acid at 40° C. was then prepared in a separate tank, and the aforementioned magnesium alloy sheets 1 were immersed therein for 2 min and washed thoroughly with water. Black smut adhered thereto. A 7.5% aqueous solution of a degreasing agent “NE-6 (product name)” for aluminum alloys at a temperature of 75° C. was prepared in a separate tank and the magnesium alloy pieces were immersed therein for 5 min and washed thoroughly with water. Then, a 20% aqueous solution of caustic soda at 75° C. was prepared in another tank and the group of magnesium alloy sheets 1 were immersed therein for 5 min and washed thoroughly with water. The above-described treatment was pretreatment, and the treatment method was identical to that of Example 1.

(35) Then, the pieces were immersed for 15 sec in an aqueous solution of citric acid with a concentration of 0.5% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. The pieces were then immersed for 2 min in an aqueous solution containing 0.12% zircon acetyl acetonate and 0.05% aqueous solution of fluorotitanic acid with a concentration of 40% at 60° C. The pieces were then placed for 10 min in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy sheets 1 on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers or the like.

(36) Further, the remaining magnesium alloy sheets 1 were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the sheets were inserted into an injection molding mold at 140° C. A total of 10 integrated composites shown in FIG. 2 were obtained in the same manner as in Example 1. The composites were placed for 1 h on the molding day into a hot air drier at a temperature of 150° C. and annealed, followed by a tensile test conducted one day after. The average shear force was 7.7 MPa (78 Kgf/cm.sup.2).

Example 4

(37) An AZ31 alloy sheet with a thickness of 0.8 mm that had an average metal crystal grain size of 7 μm was procured. The sheet was cut in the same manner as in Example 1 to obtain rectangular pieces that were immersed for 5 min in an aqueous solution of the degreasing agent “Cleaner 160” with a concentration of 10% at 75° C. and washed thoroughly with water. A 2% aqueous solution of acetic acid at 40° C. was then prepared in a separate tank, and the aforementioned magnesium alloy sheets 1 were immersed therein for 2 min and washed thoroughly with water. Black smut adhered thereto. A 7.5% aqueous solution of a degreasing agent “NE-6 (product name)” for aluminum alloys at a temperature of 75° C. was prepared in a separate tank and the magnesium alloy pieces were immersed therein for 5 min and washed thoroughly with water. Then, a 20% aqueous solution of caustic soda at 75° C. was prepared in another tank and the group of magnesium alloy sheets 1 were immersed therein for 5 min and washed thoroughly with water. The above-described treatment was pretreatment, and the treatment method was identical to that of Example 1.

(38) Then, the pieces were immersed for 15 sec in an aqueous solution of citric acid with a concentration of 0.5% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. The pieces were then immersed for 5 sec in an aqueous solution containing 2% zinc acetyl acetonate, 1% aqueous solution of titanium sulfate with a concentration of 24%, and 0.1% diammonium fluorozirconate at 70° C. and washed thoroughly with water. The pieces were then placed for 10 min in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy sheets 1 on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers or the like.

(39) Further, the remaining magnesium alloy sheets 1 were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the sheets were inserted into an injection molding mold at 140° C. A total of 10 integrated composites shown in FIG. 2 were obtained in the same manner as in Example 1. The composites were placed for 1 h into a hot air drier at a temperature of 150° C. on the molding day and annealed, followed by a tensile test conducted one day after. The average shear force was 6.9 MPa.

Example 5

(40) An AZ31B alloy sheet with a thickness of 0.8 mm that had an average metal crystal grain size of 7 μm was procured. The sheet was cut in the same manner as in Example 1 to obtain rectangular pieces that were subjected to a pretreatment including the degreasing operation. The pretreatment method was identical to that of Examples 1 to 4. Then, the pieces were immersed for 30 sec in an aqueous solution of citric acid hydrate with a concentration of 0.25% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. The magnesium pieces were then immersed for 5 min in an aqueous solution containing 20% chromic acid at 75° C. and washed thoroughly with water. The pieces were then placed for 10 min in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy sheets 1 on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers or the like.

(41) In 1 day, one piece was subjected to ESCA observations. A large amount of chromium and oxygen were observed. The main component was observed as a composite with trivalent chromium oxide or chromium hydroxide. Further, the magnesium alloy pieces were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the pieces were inserted into an injection molding mold at 140° C. A total of 20 integrated composites 7 shown in FIG. 2 were obtained in the same manner as in Example 1. The composites were directly placed for 1 h into a hot air drier at a temperature of 150° C. and annealed, followed by a tensile test conducted one day after. The average shear force was 6.6 MPa. The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h at 35° C. by using 5% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Example 6

(42) An AZ31B magnesium alloy (manufactured by Nippon Kinzoku Kogyo KK, Tokyo, Japan) with a thickness of 0.8 mm and an average metal crystal size on the surface of 7 μm that was subjected to wet buffing as a final surface processing was cut to obtain rectangular pieces of the same shape as in Example 1 and the pieces were subjected to pretreatment including the degreasing operation. The pretreatment method was identical to that of Examples 1 to 5. Then, the pieces were immersed for 30 sec in an aqueous solution of citric acid hydrate with a concentration of 0.25% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. The pieces were then immersed for 5 min in an aqueous solution containing 1% potassium carbonate at 70° C. and washed thoroughly with water. The pieces were then placed for 10 min in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy pieces on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers or the like.

(43) In 1 day, one piece was observed under an electron microscope. The results are shown in a micrograph in FIG. 5. A beautiful image in which intersecting rod-like crystals formed a net-like pattern was observed. On the other hand, the ESCA analysis revealed the presence of magnesium, oxygen, carbon and also microscopic amounts of aluminum, zinc, and silicon. Because the presence of carbon not in a microscopic amount was confirmed, it was supposed that magnesium carbonate is the main component of the surface layer. Further, the remaining magnesium alloy pieces were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the pieces were inserted into an injection molding mold at 140° C. Injection molding was performed in the same manner as in Example 1 and a total of 20 integrated composites 7 shown in FIG. 2 were obtained. The composites were placed for 1 h into a hot air drier at a temperature of 150° C. and annealed, followed by a tensile test conducted one day after. The average shear force was 7.0 MPa.

Example 7

(44) An AZ31B magnesium alloy (manufactured by Nippon Kinzoku KK) with a thickness of 0.8 mm and an average metal crystal size on the surface of 7 μm was used and the processing preceding pretreatment was performed in the same manner as in Example 1. Then, the pieces were immersed for 30 sec in an aqueous solution of citric acid with a concentration of 0.25% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. The pieces were then immersed for 10 min in an aqueous solution containing 1% calcium nitrate hydrate, 1% strontium nitrate hydrate, 0.05% sodium chloride, and 0.95% phosphorus (80%) at 65° C. and washed thoroughly with water. The pieces were then placed for 10 min in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy pieces on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers. In one day, one piece was subjected to ESCA.

(45) Magnesium, calcium, strontium, and oxygen were observed in large amounts. In addition very small amounts of zinc, aluminum, carbon, and silicon were observed. Oxides of magnesium, calcium, and strontium were considered as the main components. The analytical device used could not clarify whether a single composition or multiple compositions were present. Further, the remaining magnesium alloy pieces were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the sheets were inserted into an injection molding mold at 140° C. The injection molding was performed in the same manner as in Example 1 and a total of 20 integrated composites shown in FIG. 2 were obtained. The composites were placed for 1 h into a hot air drier at a temperature of 150° C. on the molding day and annealed, followed by a tensile test conducted one day after. The average shear force was 7.3 MPa.

Example 8

(46) An AZ31B magnesium alloy with a thickness of 0.8 mm and an average metal crystal size on the surface of 7 μm was used and the processing preceding pretreatment was performed in the same manner as in Example 1. Then, the pieces were immersed for 30 sec in an aqueous solution of citric acid with a concentration of 0.25% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. The pieces were then immersed for 2 min in an aqueous solution containing 1% vanadium trichloride at 45° C. and washed thoroughly with water. The pieces were then placed for 10 min in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy pieces on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers. In one day, one piece was subjected to ESCA. Vanadium and oxygen were observed in large amounts. In addition, a small amount of magnesium and very small amounts of zinc, aluminum, and silicon were observed. Vanadium oxide or an oxide of vanadium and magnesium were considered as the main components.

(47) Further, the remaining magnesium alloy pieces were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the sheets were inserted into an injection molding mold at 140° C. The injection molding was performed in the same manner as in Example 1 and a total of 20 integrated composites 7 shown in FIG. 2 were obtained. The composites were placed for 1 h into a hot air drier at a temperature of 150° C. on the molding day and annealed, followed by a tensile test conducted one day after. The average shear force was 7.0 MPa. The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h at 35° C. by using 5% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Example 9

(48) Example 9 was used to confirm the effect of the PPS resin. “Susteel GS-30 (product name)” (manufactured by Tosoh Corp., Tokyo, Japan), which is a PPS resin, containing 30% glass fibers was used as a resin for injection. the injection conditions during molding were as follows: injection temperature 310° C. and mold temperature 140° C. Conditions other than these injection molding conditions were identical to those of Example 1. On the molding day, four pieces were subjected to a tensile rupture test. The average shear force was 8.8 MPa (90 Kgf/cm.sup.2). Further, on the molding day, five pieces were placed for 1 h in a hot air drier at 170° C. In one day, they were subjected to a tensile test. The average shear force was 9.3 MPa.

(49) The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h by using 5% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Example 10

(50) Example 10 was used to confirm the effect of the PPS resin. The magnesium alloy pieces were treated in substantially the same manner as in Example 9 and the injection joining was performed in exactly the same manner as in Example 9. As for the synthetic resin used, the PPS composition (1) obtained in the Preparation Example 1 of a PPS composition was used instead of the “Susteel GS-30” employed in Example 9. A total of 20 integrated composites 7 shown in FIG. 2 were obtained. The resin portion had a size of 10 mm×45 mm v 5 mm, and the joint surface 6 had a size of 10 mm×5 mm and an area of 0.5 cm.sup.2.

(51) On the molding day, four pieces were subjected to a tensile rupture test. The average shear force was 13.0 MPa. Further, on the molding day, five pieces were placed for 1 h in a hot air drier at 170° C. In one day, they were subjected to a tensile test. The average shear force was 12.8 MPa. The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h at 35° C. by using 5% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Example 11

(52) Composites were obtained by exactly the same method as that of Example 10, except that the PPS composition (3) obtained in Preparation Example 3 was used instead of the PPS composition (1) obtained in Preparation Example 1 of a PPS composition. On the molding day, the composite was annealed for 1 h in at 170° C., and in two days, the shear force was measured in a tensile test machine. The average value was 12.5 MPa. The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” (manufactured by Ohashi Chemical Industries Co., Ltd., Osaka, Japan) to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h at 35° C. by using 5% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Example 12

(53) Magnesium alloy pieces were produced, injection molding was performed, and composites were obtained in exactly the same manner as in Example 10, except that the PPS composition (2) obtained in Preparation Example 2 was used instead of the PPS composition (1) obtained in Preparation Example 1. The composite obtained was annealed for 1 h in at 170° C. This was essentially the test in which a PPS resin composition containing only a filler and PPS containing but a tiny amount of polyolefin polymer was used. In one day, it was subjected to a tensile test. The average shear force for 10 pieces was 9.0 MPa. This value did not exceed about 70% the numerical value obtained in Example 1, thereby demonstrating the difference between the resin materials.

Example 13

(54) An AZ31B alloy sheet with a thickness of 0.8 mm and an average metal crystal size on the surface of 7 μm was used. The sheet was cut to obtain rectangular pieces in the same manner as in Example 1. The pieces were immersed for 5 min in an aqueous solution of a degreasing agent “Cleaner 160” with a concentration of 10% at 75° C. and washed thoroughly with water. Then, a 2% aqueous solution of acetic acid with a temperature of 40° C. was prepared in a separate tank and the alloy pieces were immersed therein for 2 min and washed thoroughly with water. Black smut adhered thereto. A 7.5% aqueous solution of a degreasing agent “NE-6 (product name)” for aluminum alloys at a temperature of 75° C. was prepared in a separate tank and the magnesium alloy pieces were immersed therein for 5 min and washed thoroughly with water. Then, a 20% aqueous solution of caustic soda at 75° C. was prepared in another tank and the group of the aforementioned alloy pieces were immersed therein for 5 min and washed thoroughly with water. The treatment described was a pretreatment, and the treatment method was identical to that of Example 1.

(55) The pieces were then immersed for 15 sec in an aqueous solution of citric acid hydrate with a concentration of 0.5% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. An aqueous solution containing 3% potassium permanganate, 1% acetic acid, and 0.5% sodium acetate hydrate and having a temperature of 45° C. was then prepared, and the pieces were immersed therein for 1 min and then washed thoroughly with water. The pieces were colored brown. The pieces were then placed for 10 min in a in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy pieces on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage. In this process, the surface to be joined (end portion on the side opposite that where the through holes were provided) was not touched with fingers.

(56) In 2 days, one piece was subjected to ESCA observations. A large amount of manganese and oxygen were observed. In addition, very small amounts of magnesium, zinc, aluminum, carbon, and silicon were observed. Manganese oxide containing manganese dioxide as the main components was assumed to be a main component. This assumption was supported by a brown color tone. Further, the remaining magnesium alloy pieces were removed in 1 day, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the pieces were inserted into an injection molding mold at 140° C. A total of 20 integrated composites 7 shown in FIG. 2 were obtained in exactly the same manner as in Example 1.

(57) On the molding day, the composites were placed for 1 h into a hot air drier at a temperature of 170° C. and annealed, followed by a tensile test conducted one day after. The average shear force was 15.1 MPa. The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h at 35° C. by using 5% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Example 14

(58) AZ31B alloy pieces were pretreated in exactly the same manner as in Example 13. The pieces were then immersed for 1 min in an aqueous solution of citric acid hydrate with a concentration of 0.25% at a temperature of 40° C. that was prepared in a separate tank and were washed with water. An aqueous solution containing 2% potassium permanganate, 1% acetic acid, and 0.5% sodium acetate hydrate and having a temperature of 45° C. was then prepared, and the pieces were immersed therein for 1 min and then washed thoroughly with water. The pieces were then placed for 15 min in a in a warm air drier at 60° C. and dried. The copper wire was pulled out from the magnesium alloy pieces on a clean aluminum foil, and the sheets were wrapped in the foil, placed in a polyethylene bag, and sealed for storage.

(59) In 2 days, one piece of these was removed and inserted in an injection molding mold at 140° C., followed by the injection of PBT composition (1). The injection molding conditions were identical to those of Example 1. The integrated object shown in FIG. 2 was obtained. It was placed for 1 h into a hot air drier at a temperature of 150° C. and annealed, followed by a tensile test conducted one day after. The average shear force was 15.8 MPa.

(60) The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. Salt water spraying was then conducted for 8 h at 35° C. by using 1% salt water, followed by washing with water and drying. No abnormalities in external appearance were observed.

Comparative Example 1

(61) Comparative Example 1 was used to confirm the effect of the conversion treatment of Example 1. Magnesium alloy sheets 1 were obtained in exactly the same manner as in Example 1, except that the conversion treatment was not performed. Thus, AZ31B magnesium alloy sheets 1 were produced, degreased, roughly etched, treated to remove smut, finely etched, and treated to remove smut. In fact, only the non-chromate treatment with a manganese phosphate system was not performed. In 2 days, the remaining magnesium alloy sheets 1 were removed, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the sheets were inserted into an injection molding mold at 140° C.

(62) The injection molding mold was closed and a PBT resin identical to that used in Example 1 was injected at an injection temperature of 260° C. The mold temperature was 140° C., and 14 integrated composites shown in FIG. 2 were obtained. The resin portion had a size of 10 mm×45 mm×5 mm, and the joint surface 6 had a size of 10 mm×5 mm and an area of 0.5 cm.sup.2. On the molding day, the composites were annealed for 1 h at 150° C. and then four composites were subjected to a tensile rupture test. the average shear force was 7.4 MPa.

(63) The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. On the next day, the coated products were sprayed with salt water for 8 h at normal temperature by using 1% salt water, followed by washing with water and drying. Fine bulging of the coated film was observed over the entire integrated product. All ten composites were subjected to a tensile rupture test. The shear force had an average value of 4.9 MPa (50 Kgf/cm.sup.2). A brittle oxide film penetrated even onto the rupture surface, and when no conversion treatment was performed, the coating alone was confirmed to make the composite unsuitable for practical use.

Comparative Example 2

(64) Magnesium alloy pieces were obtained in exactly the same manner as in Example 1, except that the conversion treatment was not performed. Thus, AZ31B magnesium alloy pieces were produced, degreased, roughly etched, treated to remove smut, finely etched, and treated to remove smut. In fact, only the non-chromate treatment with a manganese phosphate system was not performed. No crystalline matter was observed under an electron microscope, and the surface was natural oxide layer of magnesium.

(65) In 2 days, the remaining magnesium alloy pieces were removed, the side with the through hole therein was grasped with a gloved hand to prevent the adhesion of oils, and the pieces were inserted into an injection molding mold at 140° C. The mold was closed and PPS (1) obtained in the Preparation Example 1 was injected at an injection temperature of 310° C. The mold temperature was 140° C., and 14 integrated composites shown in FIG. 2 were obtained. The resin portion had a size of 10 mm×45 mm×5 mm, and the joint surface 6 had a size of 10 mm×5 mm and an area of 0.5 cm.sup.2. On the molding day, four composites were subjected to a tensile rupture test. The average shear force was 11.3 MPa.

(66) The remaining 10 integrated products were coated with a paint “Omac-Silver Metallic (product name)” to a set thickness of 10 μm and baked for 30 min at a temperature of 170° C. On the next day, the coated products were sprayed with salt water for 8 h at 35° C. by using 5% salt water, followed by washing with water and drying. Fine bulging of the coated film was observed over the entire integrated product. All ten composites were subjected to a tensile rupture test. The shear force had an average value of 7.0 MPa. A brittle oxide film penetrated even onto the rupture surface, and when no conversion treatment was performed, the coating alone was confirmed to make the composite unsuitable for practical use.

Comparative Example 3

(67) An attempt was made to manufacture composites by the same method as that of Example 10, except that the PPS composition (4) of Preparation Example 4 of a PPS composition was used instead of the PPS composition (1) of Preparation Example 1 of a PPS composition. Thus, a test was performed by using a PPS resin composition containing a very large amount of a polyolefin polymer. Such resin material should be called a polyolefin material rather than a PPS material. A large amount of gas was generated during molding, the injection molding was difficult to perform, and the operations were terminated.

Comparative Example 4

(68) An AZ31B magnesium alloy (manufactured by Nippon Kinzoku Kogyo KK, Tokyo, Japan) with a thickness of 0.8 mm and an average metal crystal size on the surface of 7 μm that was subjected to wet buffing as a final surface processing was used. It was cut to 18 mm×45 mm pieces. A through hole was provided in the end portion, a copper wire coated with vinyl chloride was passed through the pieces, and copper wire was bent so that multiple magnesium alloy pieces were not stacked. A total of ten pieces were hung down at the same time.

(69) A commercial degreasing agent “Cleaner 160” for magnesium alloys was poured into water at 65° C. and dissolved in a degreasing tank to obtain a concentration of 10%. The alloy pieces were immersed therein for 5 min and washed thoroughly with water, and dried for 15 min at 67° C. Thus, this test was designed to verify the joining strength in the case the alloy was subjected only to the degreasing treatment. After 3 days, one piece was observed under an electron microscope. The micrograph thereof is shown in FIG. 6. After one more day has passed, the alloy piece was inserted into an injection molding mold at 140° C., and a PPS composition (1) was injected. The injection molding conditions were identical to those of Example 10. When the injection molding mold was opened, an integrated article was not obtained.

Comparative Example 5

(70) A test was performed in exactly the same manner as in Comparative Example 4, except that the resin used was changed from the PPS composition (1) to the PBT composition (1) and an injection molding condition was the same as that in Example 1. In this case, too, when the injection molding mold was opened, the resin molding and magnesium alloy piece were not integrated.

(71) Table shown below summarizes the results obtained in the above-described examples and comparative examples.

(72) TABLE-US-00001 TABLE 1 Summary of Results Obtained in Examples and Comparative Examples Conversion Resin Strength Base material treatment liquid (main) (Mpa) Notes Example 1 AZ31B Manganese PBT 11.9 phosphate system Example 2 AZ31B Potassium PBT 11.6 Surface has permanganate spherical formations Example 3 AZ31B Zirconium acetyl PBT 7.7 acetonate, titanium fluoride Example 4 AZ31B Zinc acetyl PBT 6.9 acetonate, titanium sulfate Example 5 AZ31B Chromic acid PBT 6.6 Example 6 AZ31B Potassium PBT 7.0 carbonate Example 7 AZ31B Calcium nitrate PBT 7.3 hydrate, strontium nitrate hydrate Example 8 AZ31B Vanadium PBT 7.0 trichloride Example 9 AZ31B Manganese PPS 9.3 Salt water test phosphate system is possible Example 10 AZ31B Manganese PPS, olefin 12.8 phosphate system system Example 11 AZ31B Manganese PPS, olefin 12.5 phosphate system system Example 12 AZ31B Manganese PPS 9.0 Small amount phosphate system of polyolefin system is added Example 13 AZ31B Potassium PBT 15.1 permanganate Example 14 AZ31B Potassium PBT, PET 15.8 permanganate Comparative AZ31B Only etching and PBT 7.4 Salt water test Example 1 treating to is impossible remove smut Comparative AZ31B Only etching and PPS 11.3 Salt water test Example 2 treating to is impossible remove smut Comparative AZ31B Manganese PPS, olefin Molding is Small amount Example 3 phosphate system system impossible of polyolefin system is added Comparative AZ31B Only degreasing PPS, olefin No fixing Example 4 system Comparative AZ31B Only degreasing PBT, PET No fixing Example 5

INDUSTRIAL APPLICABILITY

(73) The composite of a metal and a resin and a method for manufacturing same in accordance with the present invention can be used for casings of electronic devices, housings of domestic electric appliances, structural components, machinery parts, and the like. In particular, because magnesium alloys have higher strength and bending elastic modulus per unit weight than aluminum alloys or ferrous metals, they are widely employed for structural materials and parts. Using these properties, it is possible to expect the application thereof to mobile electronic device, body parts of aircrafts, and automobile parts for which light reduction is required.