JPS6124420A - Press-molding method of thermoplastic resin - Google Patents

Abstract

PURPOSE:To obtain a molded part excellent in electromagnetic shielding effect at high speed cycle by a method wherein a metal gauze, on one surface of which thermoplastic resin molding resin layer has been placed and on the other surface of which molten resin has been supplied, is put between vertically openable forces in order to be molded after the closing of the forces. CONSTITUTION:A metal plate perforated with a large number of small holes or a metal gauze 115, on one surface of which thermoplastic resin molding resin layer 114 has been placed and on the other surface of which thermoplastic resin molten body 116 has been placed, is put between vertically openable forces 111 and 112 in order to be molded after the closing of the upper and lower forces 111 and 112. Consequently, the molding resin layer and the molten resin are joined through the perforated metal plate of the metal gauze with each other, resulting in obtaining an integral molded part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides electromagnetic wave reflection and t! The present invention relates to a method of molding a molded product with excellent shielding effect at a high cycle rate and at low cost.

In recent years, digital electronic devices have become widespread, and the electromagnetic waves generated by the ICs used in these devices are causing electromagnetic interference between digital devices, causing malfunctions and communication problems. There is a demand for molded products with a high degree of flexibility, and various methods are being considered.

On the other hand, molded products with excellent IA electromagnetic wave reflection effects are required as antenna plates (referred to as flexor-type antenna plates under μ) for receiving glue flexor-type antennas in response to damage in communications and broadcasting sanitary systems. .

%, when an electromagnetic wave is incident on a highly conductive material such as a metal, multiple reflections (B) occur in which reflection at the interface (R), absorption inside (A), and internal reflection are repeated; ) and be shielded (and 10A, +B,).

Generally, reflection loss is larger than absorption loss and is dominant. That is, materials with excellent electromagnetic wave reflection effects also have high electromagnetic wave shielding effects.

As a result of extensive studies, the inventors of the present invention found that a metal plate or wire mesh is placed on a mold that opens and closes up and down at a high cycle, and a rs resin layer (formed below) is formed on one side of the metal plate or wire mesh from a thermoplastic resin in advance. A thermoplastic resin in a molten state is placed on the other side, the upper and lower molds are closed, and pressure is applied.
We have discovered a method for molding a molded product with excellent electromagnetic wave reflection and electromagnetic wave shielding effects by welding and integrating the molded resin layer and the molten resin through the metal plate or wire mesh after cooling.

In the invention, a metal plate or wire mesh with small holes is used as an electromagnetic wave reflection and shielding material, but it is also possible to use a metal plate with small holes in it (
The reason is that the molten resin supplied to one side of the metal plate enters this hole and presses against the molded resin layer of thermoplastic resin on the other side of the metal plate.
This is the first step to weld and integrate the parts during the cooling and molding process. The size and number of holes are not specified, but preferably 1 to 8 holes.
Good.

In the present invention, unlike the case where a resin layer and a metal plate are bonded together with an adhesive, the resin layers on both sides are welded together through the small holes in the metal plate or the mesh of the wire mesh, so the durability is good. The molded product obtained by this molding method has an excellent electromagnetic wave reflection effect and can be used as an antenna plate for reflector-type antennas such as parabolic antennas, offset antennas, and Cassegrain antennas.

Additionally, due to its excellent electromagnetic shielding effect, it can be used as electromagnetic shielding products such as housings for digital electronic devices such as personal computers and word processors. The molded resin layer and the molten resin supplied on both sides of the metal plate or wire mesh must be thermoplastic resins of the same type that have good weldability.

Note that it is preferable to preheat the molded resin layer in terms of welding.

In addition, if the molded resin layer has a simple shape similar to that of a leftover type antenna plate without a ζζ shape h=yfR and has a shape close to a flat surface, a simple sheet may be used. If the product is a deep housing, it is best to shape it into that shape in advance and use it for the main molding.

For example, as described in Example 8, it may be pre-shaped by a method similar to this molding method, or it may be pre-shaped by injection molding or other methods.

Next, the molded resin layer can be used on the front side or the back side of the product, but if the product takes advantage of its electromagnetic wave reflection effect or is a flutter-type antenna plate, it can be placed on the front side (the concave side of the product). It is convenient to use. The reason is that in order to efficiently focus the electromagnetic waves reflected by the metal plate or wire mesh inside the product, it is important that the electromagnetic reflective material forms an accurate paraboloid of revolution. For this purpose, it is important that the thickness of the resin layer on the front side of the product is uniform. Of course, it is easy to make the surface of the mold for molding the front side of the product a precise paraboloid of revolution. At this point the sheet (
In this case, a sheet may be used as the molded resin layer. )
Since it is easy to obtain a product with good thickness accuracy, it is convenient to use it for the front (concave) (!lI) of the product.When molding the front side with molten resin, the molding conditions (high melt viscosity, low press pressure) , when the press speed is low, etc.), the center of the product may be thicker than the periphery.
If this happens, the electromagnetic reflective material in the product will no longer form a highly accurate paraboloid of revolution.

In the case of long antenna plates, the front side will be exposed to direct sunlight for a long period of time when installed outdoors, so we use a resin formulation with good weather resistance, and the back side is made of a highly rigid resin by adding filler. It is reasonable to use a resin formulation because it has a large reinforcing effect and requires only a small wall thickness.

Furthermore, the present invention uses a mold that opens and closes vertically, which is necessary to ensure and quickly set the electromagnetic wave reflecting and shielding material at a fixed position in the mold and to perform high-cycle molding.

In addition, in this molding method, unlike the injection molding method, the molten resin is supplied in advance so that the upper and lower molds are in contact with the magnetic wave reflecting material in an open or semi-open state (or the molten resin is supplied while the molds are closed). (However, the supply should be completed at least before the mold is completely closed.) Because the mold is shaped while the mold is closed (high-pressure molten resin is ejected from the gate around the injection molding) As the mold closes, the molten resin in contact with the electromagnetic wave reflecting and shielding material spreads over the electromagnetic wave reflecting and shielding material, so compared to when the same thing is done with injection molding, Since no excessive force is applied to the electromagnetic wave reflection and shielding material, it is possible to mold the electromagnetic wave reflection and shielding material without damaging it.

Next, a mold suitable for carrying out the present invention will be explained using figures.

Figure 1 shows a normal mold used for injection molding, and I will first explain that some problems may occur when molding with this mold. Figure 1 shows the state just before the molten resin is supplied onto the lower mold and the metal is completely closed. (1) is the upper mold, (2) is the lower mold, (3) (3) shows the state in which the molten resin supplied onto the lower mold flows through the mold space and is shaped into a shape almost similar to the product. (3) shows the state in which the molten resin has flowed into the parting surface of the upper and lower molds. When using this type of mold, as the mold closes, the part where the molten resin first reaches the end of the mold space is not yet completely closed, so (3)' If this occurs, the mold will not close completely, which will not only cause cracks in the product but also make it difficult to make the thickness of the product constant.

Figure 2 shows a mold suitable for implementing the present invention.
j) is the upper mold (2) is the lower mold, (to) is the mold space, 04
(2) is a T-shaped spacer that determines the thickness of the product, and (2) is a shear edge that allows the mating parts of the upper and lower molds to be parallel to the mold opening/closing direction (perpendicular) by several μ vertically, and to reduce this gap. It has been processed to prevent the molten resin from flowing out.

When molding is performed using this type of mold, even if the molten resin reaches the end between the gold W2 as the mold closes, the shear edge portions of the upper and lower molds are already closed, so the molten resin will not flow out from there. Since the product is shaped by pouring the material and then flowing it through the surface of the mold, it is possible to obtain a product with the desired thickness without the occurrence of flakes. Furthermore, by changing the thickness of the spacer, the thickness of the product can be easily changed.

A press machine is used to open and close the mold and pressurize it.

EXAMPLE 1 A reflector-type antenna plate was molded using the aluminum plate shown in FIG. 3 as the radio wave reflecting material.

That's it. Figure N4 is a schematic cross-sectional view of the mold during molding, (Il
l) is the upper mold, (112) is the lower mold, and the deyo mold (111) is the lower mold.
) and the lower mold (112) have a shear edge structure as shown in FIG. (tia) is Shimokin 1!4 (112)
Although not shown in the figure, the end of the molten resin passage (11B) is connected to a molten resin accumulator, and the molten resin passage (11B) of the lower mold (112) is
The peripheral area of B) has a heating and heat retention structure, and the lower mold (
112) so that molten resin can be arbitrarily supplied to the center of the tube. (114) is a thermoplastic resin sheet with a thickness of 0.6 mm, which is circular like the aluminum plate in Fig. 8, but slightly larger than the aluminum plate (115), and is cut. (115)
indicates the aluminum plate shown in FIG.

Next, let's talk about molding.

Although Figure 4 shows the mold in a slightly closed state, first open the mold completely and place the aluminum plate (112) on the lower mold (112).
5), place the resin sheet (114) on top of it, then close the mold to the state shown in Figure 4, and pour the molten resin (116) from the molten resin passageway (11B) onto the lower mold (112). Supply as shown. Then, the mold is completely closed, pressurized, and cooled to complete the molding process.

Figure 6 is a schematic diagram of the center cross section of the product thus obtained (1
14') is the resin (molded resin 1 layer') sheet shown in Fig. 4, (
115') is an aluminum plate, (116',), (116'
1 and (116) are parts shaped from the molten resin (116,), showing the main part, flange part, and rib part, respectively. ,.

/″ Then, a reflector-type antenna plate was formed.

Figure 5 is a schematic cross-sectional view of the mold during molding, (111) is the upper mold, (112) is the lower mold, and the mating part of the upper mold (iti) and the lower mold is shown in Figure @2. It has a shear edge structure as shown. (117) is a molten resin supply port, which is configured so that it can be taken out and put in between the upper and lower molds. (114) is the same sheet used in Example 1, (115) is an aluminum plate, and (116) is the molten resin supplied from the molten resin supply port (117).

Next, let's talk about molding. Open the upper and lower molds and remove the lower mold (11
2.) Place the resin sheet (114) on top, place the aluminum plate (115) on top of it, then open the molten resin supply port (117).
is placed between the upper and lower molds as shown in the figure, molten resin (116) is supplied, and after supplying, the molten resin supply port 1 (117) is moved outside between the upper and lower molds, the upper and lower molds are closed, and pressure is applied. Cool and complete molding.

FIG. 6 shows a central cross section of the product thus obtained.

The symbols are also the same as in Example 1.

Example 8 As an electromagnetic shielding material, a wire mesh with a wire diameter of 0.27 m was woven into a plain weave of 20 meshes (the opening size of the wire mesh was 1.0 Is).
) was used to mold a housing with good electromagnetic shielding effect.

(Figure 1) is a schematic cross-sectional view during molding, (tti) is the upper mold (
The solid line) and (112) are the lower mold, and the mating part of the upper mold <111) and the mold (112) has a shear edge structure as shown in FIG. (11B,) is a molten resin supply port that can be taken in and out between the upper and lower molds. Also (114.
) is a box-shaped wire mesh preformed in advance so as to be in close contact with the lower mold surface (a box-shaped wire mesh pre-shaped with the aforementioned wire mesh made of housing, (116)
is the molten resin supplied from the resin supply port (11B).

Next, regarding molding, as shown in Figure 7, the mold is fully opened.
Place four molding resin layers (-114) on the lower mold, further place a pre-shaped wire mesh (115) on top of it, supply molten resin (116) from the resin supply port (11B) on top of it, When the supply was completed, the resin supply port (11B) was moved out from between the upper and lower molds, the molds were closed, and the resin was pressurized and cooled to obtain a product.

Figure 8 is a schematic cross-sectional view of the product thus obtained.
4') and (115) are the molded resin layer (114) (constituting the outer surface of the product) and the wire mesh (115) in Fig. 7, respectively.
(116') is a resin layer molded from the molten resin (116) in Figure 7, and the resin layers (114) and (116')
are welded together via a wire mesh (115').

Note that the box-shaped molded resin layer (114) was preformed in the same manner as the above molding. That is, in this case, the lower mold is the same as shown in Fig. 7, and the lower part of the upper mold is slightly larger as shown by the dotted line (in Fig. 8, only the thickness of the wire mesh (115') and the resin layer (116') is ) Using a mold, supply resin in the same way, pressurize,
It was cooled and preformed.

4. Brief description of the drawings Figure 1 shows a schematic cross-sectional view of a type of mold commonly used in injection molding.

(1): Upper mold, (2): Lower mold, (3): Shaped resin, (3) 'The part of the molded resin that entered the mold parting part Figure 2 is the main mold. Cross-sectional schematic diagram of a mold suitable for carrying out the invention % 04: Spacer, (to): Shear edge portion FIG. 8 is an explanatory diagram of an aluminum plate provided with small holes.

(115) Ni-aluminum plate, (118): small hole FIG. 4 is a schematic cross-sectional view of the mold during molding of Example 1.

(111): Upper mold, (112): Lower mold, (11
B): Molten resin passage, (114): Resin sheet, (
115) Ni-aluminum plate, (116): Molten resin, FIG. 5 is a schematic cross-sectional view of a mold during molding in Example 2.

(111): Upper mold, (112): Lower mold, (11
4): Resin sheet, (115) Ni-aluminum plate, (11
6) : Molten resin, (117) : Molten resin supply port, FIG. 6 is a schematic cross-sectional view of the center of the product of Example 1.2.

(114'): Resin sheet (114) in Figure 4.5, (115'): Aluminum plate (115) in Figure 4.5, (116'), (116'), (116''' ): 4th
．． (116) in Fig. 5 is the main part, flange part, and rib part formed from the molten resin. Fig. 7 is a schematic cross-sectional view of the mold during molding of Example 8.

(111): Upper mold, (112): Lower mold, (11
B): Molten resin supply port, (114): Pre-shaped molded resin layer (box shape), (115): Pre-shaped wire mesh, (116): Molten resin, Figure 8 shows the product of Example 8 FIG.

(114'): Molding resin layer (114) in Fig. 7, (
115')? Figure 7 (115) wire mesh, (116')
: Layer shaped from the molten resin (116) in Fig. 7 Fig. 3 Fig. 5 Fig. 7 Fig. 8 +15'

Claims (3)

[Claims] (1) Place a metal plate or metal steel with small holes on a mold that opens and closes vertically, place a molded resin layer pre-molded from thermoplastic resin on one side of the metal plate or wire mesh, and Close the upper and lower molds by supplying molten thermoplastic resin to the sides,
A method for producing a molded article with excellent electromagnetic wave reflection and electromagnetic wave shielding effects, characterized in that the molded resin layer and the molten resin are welded and integrated through the metal plate or wire mesh by pressurizing and cooling. (2) The manufacturing method according to claim 1, wherein the molded product is an electromagnetic wave shielding product. (3) The manufacturing method according to claim 1, wherein the molded product is a reflector type antenna plate.