JP3294724B2 - In-mold molding method and housing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-mold molding method for integrally molding a metal part and a synthetic resin, and a housing.

[0002] With the recent advances in computer technology and communication technology, notebook personal computers, electronic organizers, portable telephones, and various other small portable electronic devices have become widespread. In order to improve the convenience of these electronic devices, it is extremely important to improve the functions and to reduce the weight.

[0003] In the above electronic equipment, the weight of the housing occupies about 30 to 50% of the whole equipment. Therefore, if the housing can be further reduced in weight, it can greatly contribute to reducing the weight of the device. That is why it is desired to reduce the weight of the housing.

[0004]

2. Description of the Related Art Conventionally, as a material for a housing, a light-weight,
Synthetic resins are generally used in terms of productivity, external shape, and the like. One of the techniques for reducing the weight of the housing is to reduce the thickness. However, it is usually difficult to reduce the thickness of the ABS resin used for the housing due to insufficient strength.

The inventors of the present invention provide an aromatic polyamide,
We studied thin-wall molding of the housing using high-strength engineering plastics such as PPS. However, even when using these engineering plastics, rigidity,
The strength was insufficient. In particular, in portable electronic devices such as a notebook personal computer and a word processor, it is considered that dropping while carrying or carrying frequently occurs. Therefore, it is required to have a drop impact resistance so as not to be damaged when dropped from a height of, for example, 1 m. However, at present, there is no thin, high-strength synthetic resin that can satisfy this requirement.

In order to satisfy these required performances, Al
There is a method of manufacturing a housing from a metal material such as an (aluminum) plate or an aluminum alloy die-cast. However, the Al plate has a drawback that it is difficult to form bosses, ribs, fitting portions, and the like.
mm or less is difficult. Furthermore, a housing using such a metal has too high a rigidity to absorb an impact force applied to the device. Therefore, when an impact is applied to the device, the housing is not damaged, but there is a high possibility that internal electronic components may be damaged or defective. As described above, the synthetic resin or metal alone cannot completely satisfy the above-mentioned required characteristics. Therefore, a housing is manufactured by an in-mold molding method of integrating a synthetic resin and a metal (for example, JP-A-5-261823).

In the conventional in-mold molding method, there are a method of imparting an anchor effect and a method of applying an adhesive to the metal component in order to improve the bonding strength (adhesion) between the metal component and the synthetic resin. .

[0008]

In the method of imparting an anchor effect, an uneven portion such as a hole or a cut-and-raised piece is provided in a predetermined region on the surface of a metal component, and the uneven portion is formed by shrinkage during molding of the synthetic resin. Bite. Thereby, the joining force between them is improved.

However, the bonding force is affected by structural factors such as the rigidity and molding shrinkage of the synthetic resin, and the shape and arrangement of the uneven portions. Therefore, there is a disadvantage that the structure of each device needs to be studied, and the time required for the production is long. In addition, since shrinkage occurs during molding and cooling of the synthetic resin, floating occurs between the metal component and the synthetic resin, thereby deteriorating aesthetic appearance and easily causing dew condensation, which is not very preferable as a housing for electronic devices. .

In the method of applying an adhesive to a metal part, there are problems such as that the adhesive flows due to a high pressure at the time of injection and that the adhesive is deteriorated by a high temperature. In addition, an increase in the number of steps for applying the adhesive increases the manufacturing cost and deteriorates the working environment. Further, there is a problem that a special device is required for uniformly applying the adhesive.

The present invention has been made in view of the above-mentioned problems, and can improve the bonding force between a synthetic resin and a metal component without imparting an anchor effect and without applying an adhesive. It is another object of the present invention to provide an in-mold molding method suitable for manufacturing a housing of a portable device.

[0012]

According to a first aspect of the present invention, there is provided a method comprising: a metal part made of a material mainly containing aluminum; and a synthetic resin made of a polyamide resin or a resin mixture containing at least 40% by weight of a polyamide resin. An in-mold molding method for integrally molding the metal part, after passing through a cleaning step of cleaning the metal part and a processing step of generating a hydrated oxide on the surface of the metal part, disposing the metal part in a mold Then, the synthetic resin is molded in the mold to perform integral molding with the metal component.

According to a second aspect of the present invention, there is provided an in-mold method for integrally molding a metal part made of a material mainly containing aluminum and a synthetic resin made of a polyamide resin or a resin mixture containing at least 40% by weight of a polyamide resin. A molding method, a degreasing step of degreasing the metal component, an oxide film removing step of removing an oxide film of the metal component,
And after a processing step of generating a hydrated oxide on the surface of the metal component, disposing the metal component in a mold, performing molding of the synthetic resin in the mold, and integrally molding with the metal component. I do.

[0014] In the method according to the third aspect of the present invention, the processing step includes a step of immersing the metal component in hot water at 60 to 90 ° C for 1 to 10 minutes. The method according to the invention of claim 4 includes a step of heating the temperature of the mold to 80 to 100 ° C.

In the method according to the fifth aspect of the present invention, the metal component is a thin metal plate forming a flat portion of a housing.
7. The invention according to claim 6, wherein the housing is made of a plate-like material containing aluminum as a main component, a metal component having a hydrated oxide formed on its surface, and a polyamide resin or a resin mixture containing at least 40% by weight of a polyamide resin. And a synthetic resin consisting of

[0016]

According to the present invention, dirt and an oxide film are removed by a degreasing process and an oxide film removing process on the surface of a metal component, and a hydrated oxide is generated on the surface of the metal component. By performing resin molding in this state, bonding between the metal component and the resin portion becomes possible. Furthermore, stable bonding strength or bonding strength can be obtained by subjecting the metal component to hot water treatment and forming an appropriate amount of hydrated oxide on the aluminum surface.

The bonding mechanism between the molten resin and the metal component during molding is considered as follows. That is, the polyamide resin has an amide group (—CONH—) in its structure.
, It has a strong polarity and shows strong adhesion at high temperatures. Aluminum has an oxide film or a hydrate layer called a barrier layer or a bulk layer on its surface. A strong adhesive force (bonding force) is exhibited by a reaction between a strongly polar amide group in the resin and a hydroxyl group on the aluminum surface.

[0018]

FIG. 2 is a perspective view showing a cross section of a part of a housing 5 manufactured by the in-mold molding method of the present invention.
FIG. 4 is an enlarged sectional view showing a bonding portion BD between the metal component 11 and the resin portion 12 of the housing 5, and FIG. 4 is a perspective view of a pen-input type notebook personal computer 2 manufactured using the housing 5. is there.

The housing 5 shown in FIG. 2 is used as a bottom cover of the notebook personal computer 2 shown in FIG. A liquid crystal screen HG is provided on the upper surface of the notebook personal computer 2. The housing 5 is 150 mm long,
Plate-shaped metal part 11 having a width of 250 mm and a thickness of 0.5 mm
And the resin portion 12 made of a synthetic resin and including the ribs 21 and the bosses 22 are integrally formed by an in-mold molding method.

For the metal part 11, a metal mainly composed of aluminum is used as a material. For example, metallic aluminum, duralumin, a high-tensile aluminum alloy containing magnesium, and other ordinary aluminum alloys are used. By using an aluminum alloy, a metal part whose surface is covered with a hydrated oxide is obtained, and the adhesiveness with a synthetic resin is enhanced.

[0021] The alloy composition of the aluminum alloy does not particularly affect the adhesiveness by molding. An appropriate one may be selected according to the price and the required mechanical strength. The resin portion 12 is made of a polyamide resin or a polyamide resin of at least 4
A synthetic resin composed of a resin mixture containing 0% by weight is used. By a polyamide resin containing at least 40 by weight%, the adhesion highly bound strongly polyamide resin and aluminum, the molded article can be obtained stably joined.

As a synthetic resin used for the resin portion 12, a commercially available resin such as nylon 6 or nylon 66 may be generally used. In addition, nylon 46, nylon 61
0, nylon 11, nylon 12, etc. Normal,
In many cases, no filler is contained or glass fibers are contained in an amount of about 30% by weight. The presence or absence of the filler does not particularly affect the adhesiveness by molding. In order to suppress molding shrinkage, those containing glass or carbon fiber are preferable. When mechanical strength is required, it is preferable to use one containing the above-mentioned filler or use an aromatic polyamide such as a meta-xylylene group-containing polyamide. According to this, the dimensional stability against moisture absorption is better than that of a normal polyamide resin, and thus it is suitable for a housing for a portable device which is expected to be used in various environments. The adhesive strength is also about 20% higher than that of a normal polyamide resin.

As shown in FIG. 3, the metal portion 11 and the resin portion 1
2 are integrally fixed by an adhesive force (joining force) by molding in the adhesive portion BD. Next, an in-mold molding method for the housing 5 will be described.

FIG. 1 is a flowchart showing an in-mold molding method according to the present invention. First, the metal component 11 is degreased (# 1). In the degreasing process, the metal component 11 is cleaned with an organic solvent, a cleaning agent, or the like. Thereafter, an oxide film removing process is performed (# 2). In the oxide film removing process, dirt and an oxide film are removed by acid cleaning or alkali cleaning. Through these steps, the metal component 1
On the surface of No. 1, metallic aluminum, alumina, and alumina hydrate (hydrated oxide) are formed. By performing resin molding in this state, the metal component 11 and the resin portion 12 can be bonded. However, before proceeding to the forming step, the metal part 11 is further immersed in warm water (step ##).
By performing 3), stable adhesive strength (joining strength)
Is obtained.

In the hot water treatment step # 3, the metal component 11 is immersed in hot water at 60 to 90 ° C. for 1 to 10 minutes. For hot water at 60 ° C., immersion for 1 to 8 minutes is preferable, and for warm water at 80 ° C., immersion for 1 to 5 minutes is preferable. In the case of hot water of 90 ° C., immersion for about 1 to 2 minutes is sufficient.

The bonding mechanism between the molten resin and the metal in this case is considered as follows. That is, since the polyamide resin has an amide group (-CONH-) in its structure, the polarity is strong. Therefore, it exhibits strong adhesiveness at high temperatures. On the other hand, aluminum has an oxide film or a hydrate layer called a barrier layer or a bulk layer on its surface. It is considered that a strong adhesive force is exhibited by a reaction between a strongly polar amide group in the resin and a hydroxyl group on the aluminum surface.

In general, to stabilize the surface by sealing micropores on the surface of aluminum,
A step called a chemical conversion treatment or a sealing treatment may be performed. The hot water treatment step performed in this embodiment is similar to the chemical conversion treatment or the sealing treatment that is generally performed as described above, but the treatment time and the like are different from each other.

After performing the degreasing process, the oxide film removing process, and the hot water process, the metal component 11 is placed at a predetermined position in the mold (# 4). After the mold is clamped, the synthetic resin is molded in the mold to integrally mold the metal part 11 and the resin part 12 (# 5). As a method of molding a synthetic resin, an injection molding method, a press molding method, or another resin molding method is used. A higher mold temperature and a higher resin temperature tend to increase the adhesive strength. This is considered because the higher the temperature of the polyamide resin, the higher the tackiness. Therefore, it is desirable that the mold temperature be high.
The range of -100 ° C is preferred.

The metal part 11 and the resin part 1 of the obtained casing 5
2 has an adhesive strength of about 40 kgf / cm ² or more. When the hot water treatment step was not performed, the adhesive strength was about 30 kgf / cm ² .

Next, a specific example will be described. [Specific Example 1] Aluminum plate (150 × 250 × 0.5
mm, JIS A5052), a metal part 11 is produced, ultrasonically cleaned with acetone, an oxide film is removed with 10% by volume dilute sulfuric acid (60 ° C.), washed with water and ethanol, and then dried with hot air did.

After the mold was opened and the metal component 11 was placed at a predetermined position, the mold was clamped, and injection molding was performed using nylon 6 (Toray Amilan CM1007) as the material of the resin portion 12. The molding conditions are a resin temperature of 250 ° C., an injection set pressure of 700 kgf / cm ² , and a mold temperature of 90 ° C.

Using the obtained casing 5, a notebook personal computer 2 shown in FIG. 4 was manufactured and dropped on concrete from a height of 1 m. As a result, cracks occurred at the corners of the housing 5 that collided with the concrete, but there was no abnormality in the internal device. Next, a centralized load of 10 kgf / cm ² was applied to the notebook personal computer 2, but both the housing 5 and the entire device were normal. [Specific Example 2] As the material of the resin portion 12, instead of the nylon 6 used in the specific example 1, a resin obtained by kneading the nylon 6 used in the specific example 1 with 15% by weight of glass fiber and 3% by weight of a rubber component is used. Otherwise, in the same manner as in Example 1, a housing 5a and a notebook personal computer 2a were manufactured. In the drop test, the housing 5a was not damaged. There was no abnormality in the centralized load test. [Specific Example 3] Duralumin (JIS A2011) was used as the material of the metal component 11. After the metal component 11 is subjected to the same oxide film removal processing and cleaning processing as in the specific example 1,
Hot water treatment was performed at a treatment temperature (liquid temperature) of 60 ° C. for a treatment time of 1 minute. Nylon MXD6 (Mitsubishi Gas Chemical Reny 6002) was used as a synthetic resin. Otherwise, in the same manner as in Example 1, a housing 5b and a notebook personal computer 2b were manufactured.

In the drop test, no damage was found in either the housing 5b or the entire device. [Specific Example 4] 99% aluminum (JIS A1100) was used as the material of the metal component 11. Otherwise, in the same manner as in Example 3, a housing 5c and a notebook personal computer 2c were manufactured.

In the drop test, no damage was found in either the housing 5c or the entire device. Specific examples 1 to above
4. Evaluation test TE for adhesion strength using test piece 31
ST1 was performed.

FIG. 5 is a sectional front view of a test piece 31 used in the evaluation test TEST1, and FIG. 6 is a plan view of the test piece 31.
In the evaluation test TEST1, the test piece 31
And the resin portion 33 are bonded at the bonding portion BD1 to be integrally formed. The size of the bonding portion BD1 is 8 × 20
mm.

An aluminum plate (JIS A5052) was used as the material of the metal part 32. The metal parts 32
Ultrasonic cleaning with acetone, 10% by volume dilute sulfuric acid (60 ° C)
After removing the oxide film by washing with water and ethanol, a warm water treatment was performed at a treatment temperature of 60 ° C. for a treatment time of 1 minute. Nylon 6 (Toray Amilan CM)
1007) and nylon MXD6 (Mitsubishi Gas Chemical Reny 6002).

A tensile shear test was performed on the test piece 31. As a result, in the case of the former nylon 6, 35.4 kgf / c was used.
m ² , 47.1 kgf for the latter aromatic polyamide
/ Cm ² . The latter was stable at a slightly higher strength than the former.

Further, the test piece 31 was subjected to an adhesive strength evaluation test TEST2 while changing the processing temperature and the processing time in the hot water processing step. At this time, the material of the metal part 32 is an aluminum plate (JIS A5052), and the material of the resin part 33 is nylon 6 (Amilan CM100, Toray).
7). Processing conditions other than hot water treatment are evaluation tests TES
This is the same as in the case of T1. FIG. 7 shows the results.

As shown in FIG. 7, the processing temperature is 60 ° C.
In the case of (1), the processing time is preferably 1 to 8 minutes, and when the processing temperature is 80 ° C., the processing time is preferably 1 to 5 minutes. It can be seen that the higher the processing temperature, the shorter the processing time.

The test piece 31 was subjected to an adhesive strength evaluation test TEST3 while changing the mold temperature. At this time, the treatment temperature of the hot water treatment step was 80 ° C., and the treatment time was 1.5.
Minutes. The processing conditions other than the materials of the metal part 32 and the resin part 33 and the hot water processing are the same as those of the evaluation test TEST2. FIG. 8 shows the results.

As shown in FIG. 8, when the mold temperature is 70 ° C., the adhesive strength is weak, and when the mold temperature is 75 ° C., the adhesive strength is unstable. The higher the mold temperature, the higher the adhesive strength, and the mold temperature is preferably in the range of 80 to 100 ° C.

[0042]

According to the first to fifth aspects of the present invention,
The joining force between the synthetic resin and the metal component can be improved without providing an anchor effect and without applying an adhesive. Since the generation of bonding force does not depend on the structure,
The integration of the synthetic resin and the metal component is easily performed without forming the metal component in a special shape unlike the conventional in-mold molding method.

The composite part produced by the in-mold molding method of the present invention is excellent in rigidity, impact resistance, light weight,
The in-mold molding method of the present invention is suitable for manufacturing a housing of a portable electronic device because it has high strength, is easy to perform hot water treatment, has low equipment cost, and has high productivity.

According to the invention of claim 6, it is possible to obtain a light-weight, high-strength housing which is excellent in rigidity and impact resistance.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an in-mold molding method according to the present invention.

FIG. 2 is a perspective view showing a cross section of a part of a housing manufactured by the in-mold molding method of the present invention.

FIG. 3 is an enlarged cross-sectional view showing a bonding portion between a metal component and a resin portion of a housing.

FIG. 4 is a perspective view of a pen-input type notebook personal computer manufactured using a housing.

FIG. 5 is a sectional front view of a test piece used for an evaluation test.

FIG. 6 is a plan view of a test piece used for an evaluation test.

FIG. 7 is a graph showing the results of an evaluation test of adhesive strength using the processing temperature and the processing time as parameters.

FIG. 8 is a graph showing the results of an evaluation test of adhesive strength using mold temperature as a parameter.

[Explanation of symbols]

 5 Housing 11 Metal part 12 Resin part 31 Test piece 32 Metal part 33 Resin part

Continuation of front page (56) References JP-A-60-129224 (JP, A) JP-A-6-29669 (JP, A) JP-A-6-55572 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) B29C 45/00-45/84 C23G 5/00 H05K 5/02

Claims (6)

(57) [Claims] 1. An in-mold molding method for integrally molding a metal component made of a material containing aluminum as a main component and a synthetic resin made of a polyamide resin or a resin mixture containing at least 40% by weight of a polyamide resin, After passing through a cleaning step of cleaning the part and a processing step of generating a hydrated oxide on the surface of the metal part, the metal part is placed in a mold, and the synthetic resin is molded in the mold. And performing an integral molding with the metal part. 2. An in-mold molding method for integrally molding a metal part made of a material containing aluminum as a main component and a synthetic resin made of a polyamide resin or a resin mixture containing at least 40% by weight of a polyamide resin. After a degreasing step of degreasing a part, an oxide film removing step of removing an oxide film of the metal part, and a processing step of generating a hydrated oxide on the surface of the metal part, the metal part is placed in a mold. And molding the synthetic resin in the mold to perform integral molding with the metal component. 3. The in-mold molding method according to claim 1, wherein the processing step includes a step of immersing the metal component in hot water at 60 to 90 ° C. for 1 to 10 minutes. 4. The in-mold molding method according to claim 3, further comprising a step of heating the temperature of the mold to 80 to 100 ° C. 5. The in-mold molding method according to claim 1, wherein the metal component is a thin metal plate forming a plane portion of a housing. 6. A metal part made of a plate-like material containing aluminum as a main component and having a hydrated oxide formed on its surface,
A housing formed by integrally molding a polyamide resin or a synthetic resin comprising a resin mixture containing at least 40% by weight of a polyamide resin in a mold.