JPH066126A - Manufacture of thick resin lens antenna - Google Patents

Abstract

PURPOSE:To provide a thick resin lens antenna inexpensively in which a surface defect such as shrink or swirl mark and an internal defect such as void hardly take place and the electric characteristic such as a dielectric constant is uniform. CONSTITUTION:A synthetic resin material including foaming agent is put in a metallic die comprising an upper die 11 and a lower die 12, the filling quantity of the resin is selected to be a cavity volume or over and foaming injection molding is attained so that a foaming magnification is a multiple of 1.1 or less under the application of holding pressure of 0kg/cm<2> or more. Thus, a resin lens antenna 13 is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a dielectric lens antenna made of thick resin, and more particularly to a method for manufacturing a thick resin lens antenna using foam injection molding.

[0002]

2. Description of the Related Art A dielectric lens antenna made of synthetic resin is made of a thick synthetic resin molding. As a method of manufacturing such a thick resin lens antenna, conventionally,
The injection compression molding method and the structural foam molding method (SF molding method) have been adopted. In the injection compression molding method, as shown in FIG. 3, the upper mold 1 and the lower mold 2 are opposed to each other with a gap t therebetween, the molding material is injected, and then the mold is clamped.
Compress and mold.

A thick resin lens antenna obtained by the above injection compression molding method is shown in FIG. 4 in a longitudinal sectional view. Since the lens antenna 6 is obtained by the injection compression molding method as described above, the molding density is high, and therefore defects such as sink marks and voids are unlikely to occur. That is, when a thick resin lens antenna as described above is obtained by a normal injection molding method, a sink mark 7 is generated on the surface as shown in FIG. 5, or many voids 8 are generated in the molded body. To do. On the other hand, in the injection compression molding method, since the molding density is increased by compression,
The occurrence of sink marks and voids as described above is prevented.

On the other hand, in the SF molding method, a synthetic resin containing a foaming agent smaller than the volume of the cavity is injected into the cavity of the mold and foamed in the cavity to obtain a thick resin lens antenna having a predetermined shape. ing. FIG. 6 shows a sectional view of a thick lens antenna obtained by the SF molding method. In this method, the thick resin lens antenna 9 conforming to the shape of the cavity is obtained by foaming.

[0005]

In the injection compression molding method,
Although it is possible to obtain a thick resin lens antenna 6 having a constant dielectric constant, which is unlikely to cause defects such as sink marks and voids,
Since the mold structure is complicated, there is a problem that the cost is high. In addition, there is a problem that a dedicated molding machine for injection compression must be used. On the other hand, S
In the F molding method, although the mold structure is not complicated as compared with the case of the injection compression molding method, the foaming ratio is likely to partially vary in the obtained lens antenna 9, and therefore the dielectric constant in the lens antenna 9 becomes constant. Hard to become. In addition, there is a problem that a bubble pattern called a swirl mark is generated on the surface.

Therefore, an object of the present invention is that a sink mark, a swirl mark, or a void inside is unlikely to occur on the surface,
Another object of the present invention is to provide a method capable of inexpensively manufacturing a thick resin lens antenna having uniform electric characteristics such as dielectric constant and Q using a relatively simple mold.

[0007]

According to the present invention, when a foaming agent-containing synthetic resin material is injected into a mold and foam-molded, the filling amount of this resin is made equal to or larger than the cavity volume and a holding pressure is applied. A method of manufacturing a thick resin lens antenna, characterized in that foam molding is performed in such a state that the expansion ratio is 1.1 times or less. The details of the configuration of the present invention will be described below.

The synthetic resin material used in the present invention is capable of exhibiting a dielectric property sufficient to form a dielectric lens antenna, and is optional as long as it is possible to carry out foam injection molding described later. For example, polyethylene, polystyrene, polybutylene terephthalate, ABS resin or the like can be used. Further, a composite material obtained by mixing these synthetic resin materials with a dielectric ceramic or glass may be used.

As the foaming agent contained in the synthetic resin, a foaming agent conventionally used for foam molding, for example, azodicarbonamide (ADCA) or p, p-oxybenzenesulfonyl hydrazide (OBSH) is used. Can be used. In the present invention, the foaming agent is blended in order to compensate for the holding pressure described later and prevent the occurrence of surface defects (sinks) and internal defects (voids) of the thick resin molding.

The blending ratio of the foaming agent varies depending on the desired density in the lens antenna, but is usually blended in the range of 0.05% by weight to 3.0% by weight with respect to the synthetic resin material. If the blending ratio of the foaming agent is less than 0.05% by weight, the effect of preventing the occurrence of defects due to foaming is insufficient,
This is because when the content is more than 3.0% by weight, the foaming ratio exceeds 1.1 times even if the following holding pressure is applied, and the electrical performance such as dielectric property is deteriorated.

As a method of incorporating the foaming agent into the synthetic resin material, an appropriate method such as masterbatch or compound can be adopted. In the manufacturing method of the present invention, the foaming agent-containing synthetic resin material prepared as described above is injected into the mold to perform foam molding. At this time, the holding pressure is 0.
Foam molding is performed under a pressure of not less than kg / cm ² . As described above, the reason why molding is performed under a pressure of 0 kg / cm ² or more is to suppress foaming by the foaming agent and thereby obtain a dense molded body.

The foaming agent-containing synthetic resin material is injected in an amount slightly larger than the volume of the cavity of the mold. Specifically, it is injected in a range of about 100% by volume to 120% by volume of the volume of the cavity, and the expansion ratio is about 1.1 times or less. Molding is performed in the same manner as conventional foaming injection molding, except that the pressure of 0 kg / cm ² or more is applied and the foaming ratio is 1.1 times or less.
That is, as a mold to be used, a mold having a relatively simple structure used in conventional foam injection molding can be used.

[0013]

According to the method of manufacturing the thick resin lens antenna of the present invention, in the foam injection molding, as described above, 0 kg / cm.
A holding pressure of ² or more is applied. That is, molding is performed under high pressure injection molding conditions instead of normal injection foam molding conditions. Further, the molding is performed so that the expansion ratio is 1.1 times or less.

Therefore, the solidification shrinkage of the resin inside the thick-walled molded body is compensated by the holding pressure, whereby a dense molded body can be obtained. Further, in the production method of the present invention, the insufficient solidification shrinkage due to the holding pressure is compensated by the foaming action of the foaming agent, so that the occurrence of defects such as sink marks and voids is effectively prevented. .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be clarified by describing the embodiments of the present invention. As a synthetic resin material, polypropylene (manufactured by Mitsui Petrochemical Co., Ltd., trade name: FR-P
P, grade: K7000) to 100 parts by weight of blowing agent (Mitsubishi Petrochemical Co., Ltd., trade name: Polypan 2060) 0.5
A foaming agent-containing synthetic resin material was prepared by blending parts by weight.

The above-mentioned foaming agent-containing synthetic resin material was injected into the cavity of the mold in which the temperatures of the upper mold 11 and the lower mold 12 shown in FIG. (1) Injection pressure: 1448 kg / cm ² (2) Injection speed: 114 cm ³ / sec

Thereafter, a holding pressure was applied under the following conditions to carry out foam injection molding. (1) holding pressure ... 1267kg / cm ^{2 (2)} pressure-holding time ... 20 sec (3) cooling time of the coercive depressurizing ... 540 seconds (4) back pressure ... 5 kg / cm ²

Injection of the synthetic resin material containing the foaming agent
The volume of the cavity and the spool and run.
Total volume of nar 1087 cm³Against 1206
cm ³The synthetic resin material containing the foaming agent was injected at a ratio of. Up
The thick resin lens antenna obtained as described above is shown in FIG.
Shown in. In the thick resin lens antenna obtained,
No sink marks, swirl marks, or voids inside
Did not occur. Also, the obtained lens antenna
When the dielectric constant of each part of 13 was measured, the lens
Dielectric constant is almost constant over the entire antenna 13.
Was confirmed.

[0019]

As described above, according to the present invention, the foaming agent-containing synthetic resin material has a foaming ratio of 1.1 times or less in the state where the holding pressure of 0 kg / cm ² or more is applied as described above. Since it is foamed and injection molded so that
It is possible to obtain a lens antenna made of a thick resin having uniform electric characteristics such as. In addition, due to the action of the foaming agent contained, no defects such as sink marks on the surface, swirl marks, or voids inside are generated.

Further, since the manufacturing method of the present invention can be carried out using a mold of a usual injection molding method, the dense and defect-free thick resin lens antenna as described above can be manufactured at a low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a step of molding a foaming agent-containing synthetic resin material in a mold in an example.

FIG. 2 is a cross-sectional view showing a thick resin lens antenna obtained in an example.

FIG. 3 is a sectional view for explaining a mold used in a conventional manufacturing method.

FIG. 4 is a cross-sectional view showing a thick resin lens antenna obtained by a conventional injection compression molding method.

FIG. 5 is a cross-sectional view for explaining a defect of a thick resin lens antenna obtained by normal injection molding.

FIG. 6 is a cross-sectional view of a thick resin lens antenna obtained by a conventional structural foam molding method.

[Simple explanation of symbols]

 11 ... Upper mold 12 ... Lower mold 13 ... Thick resin lens antenna

Claims (1)

[Claims] 1. When a synthetic resin material containing a foaming agent is put into a mold and foam-molded, the filling amount of this resin is made equal to or more than the cavity volume, a holding pressure is applied, and a foaming ratio is 1. A method of manufacturing a thick resin lens antenna, characterized by performing foaming injection molding so as to be 1 time or less.