JP2001030284A - Injection molding method and injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding method, in which neither waste of material nor waste in a process develops, and an injection molding. SOLUTION: An insert article 1 in coated with a silicon rubber primer at its peripheral surface at a part to be injected as a processing agent in advance, is installed at a predetermined position between an upper side mold and a lower side mold. Under the state just mentioned above, injection material is injected in the mold. Since the silicone rubber primer forms an elastic primer layer P on the part to be injected of the insert article 1, the primer layer P deforms along the shape of a gap formed between the under surface of the upper side mold and the top surface of the insert article 1 so as to clog the gap, no injection material flows in the gap, resulting in preventing a burr from forming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method and an injection molded product, and more particularly to an injection molding method for injecting an injection material into a predetermined position (a portion to be injected) of a substrate fixed in a mold, called an insert product. TECHNICAL FIELD The present invention relates to an injection molding method called insert molding, which obtains a molded product by performing molding, and a molded product.

[0002]

2. Description of the Related Art Conventionally, when insert molding is performed, an injection material is injected into a mold while the insert is mounted in a mold that can be divided into upper and lower parts, and injected into a predetermined portion of the insert. Form a layer of material.

FIG. 9 shows a mold 1 for performing insert molding.
FIG. 4 is a vertical cross-sectional view schematically showing the inside of 00. As shown in FIG. 9, this mold 100 has a structure capable of being divided into an upper mold 101 and a lower mold 102, and an insert product is provided between the upper mold 101 and the lower mold 102. 20
0 is pinched and mounted at a predetermined position. The injection material is injected into a predetermined portion of the insert 200, that is, the injection target portion. The upper mold 101 has an injection port 10 at a position corresponding to the injection target portion of the insert 200.
3, 104 are provided, and these injection ports 103,
By injecting the injection material from the injection material 104, the injection material is injected into the injection target portion of the insert 200. Accordingly, there is no gap between the insert 200 and the mold 100, and it is necessary that the insert 200 can be accurately mounted at a predetermined position.

[0004]

However, depending on the material and type of the insert, there may be variations in shape and size. For example, in the case of an insert product formed of a brittle material such as ceramic, casting, or graphite, shrinkage is likely to occur during firing, and thus the size and shape of each product tend to vary. In particular, if the actual thickness of the insert 200 is smaller than the thickness of the insert mounting portion in the mold 100, the gap between the inner wall surface of the mold near the injection port 103 of the mold 100 and the surface of the insert 200 is small. Gaps occur. When the injection material is injected in a state where the gap is formed, FIG.
As shown in (b), the injection material injected from the injection port 103 flows into this gap to generate burrs. This burr of the injection material requires an additional step of deburring operation, which is not desirable in terms of work efficiency, and also leads to waste of the injection material, which is not preferable in terms of manufacturing cost.

The inner wall surface of the mold 100 and the insert 20
As a method of eliminating the gap between the upper mold 101 and the lower mold 102, there is a method of increasing the tightening strength of the mold 100 and strongly pressing the upper mold 101 and the lower mold 102. However, when the tightening strength of the mold 100 is increased, the upper mold 101 and the lower mold 10
Since a strong pressing force acts on the insert 200 sandwiched between the insert 200 and the insert 200 made of a brittle material such as ceramics, casting, graphite, etc., the insert 200 is deformed or broken and the defect rate rises. Invite.

In particular, when an injection material having a low viscosity and a high fluidity such as a liquid silicone resin is used as the injection material, the injection material easily flows into the gap even in a small gap, and burrs are formed. It is very difficult to completely close the gap. For example, if a gap of 5/1000 mm or more is formed between the mold and the insert product, burrs are immediately generated.

As a countermeasure against the variation of the insert product, a method of forming a relief groove in advance is disclosed in Utility Model Publication No. JP-A-4-137817, Patent Publication No. JP-A-4-344212, Patent Publication No. Hei 3-251
765 and the like. In the method described in these, when a gap is formed between the mold and the insert product, a groove through which the injection material flowing into the gap is formed is formed on the inner surface of the mold in advance, and excess injection material is formed. In this method, the burrs are made to cover the insert product, and after removing the insert product from the mold, unnecessary injection material is removed by stripping.

[0008] However, this method consumes useless injection material, and there is a problem that costly problems remain when expensive injection material is used. In addition, there is a need for a step of peeling off the solidified excess injection material, and there is a problem that waste in the manufacturing process cannot be eliminated.

The present invention has been made to solve these problems. That is, the present invention has no waste of materials,
It is an object of the present invention to provide an injection molding method and an injection molded product without waste in the process.

[0010]

The injection molding method according to the present invention is an insert injection molding method for fixing a base in a mold and injecting an injection material into an injection portion of the base. The method includes a step of applying a treatment agent around an injection section, a step of mounting the base in a mold, and a step of injecting an injection material into the mold.

[0011] The injection molded article of the present invention comprises a base, a primer layer formed on the surface of an injection portion of the base, and an injection material layer formed on the primer layer. In the above invention, the substrate may be a substrate made of a brittle material. The brittle material is, for example, carbon, ceramic, metal, resin, or the like.

As the treatment agent used in the injection molding method, a silicone rubber primer is preferable. Among the silicone rubber primers, (a) an organopolysiloxane having at least two silicon-bonded aliphatic unsaturated hydrocarbon groups, and (b) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms , (C) a reinforcing silica, (d) a platinum-based catalyst, and (e) a self-adhesive aid.

According to the present invention, in performing insert injection molding, a processing agent is applied beforehand around the area to be injected of the base and then injection is performed. Therefore, the processing material is applied between the base and the inner wall surface near the injection port of the mold. To prevent the injection material from flowing into this gap. As a result, the occurrence of burrs is prevented beforehand, so that deburring work becomes unnecessary and waste of the injection material can be prevented. Further, since it is not necessary to excessively increase the clamping strength of the mold in order to eliminate the gap between the inner wall surface of the mold and the substrate, breakage of the substrate due to the increase in the clamping strength is also prevented.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing the flow of each step of the injection molding method according to the present invention.

First, an insert is prepared as a substrate to be subjected to injection molding. FIG. 2 is a perspective view of an insert 1 constituting the base of the injection-molded article according to the present invention, and FIG. 3 is a plan view of the insert 1. This insert 1
A case in which a circular silicone molded body is injection-molded on the surface of the substrate will be described.

Next, a treatment agent P is applied to a portion of the insert 1 where injection molding is to be performed (STEP 1). At this time, the treating agent is applied slightly wider than the portion where the silicone molded body is formed. The treatment agent used here is a treatment agent suitable for filling the gap between the insert 1 and the inner wall of the mold.
Here, the properties required for the treatment agent are such that it has adhesiveness to both the insert product (substrate) and the injection molding material, and can function as a part of the injection molded product even after the injection material is injected. Is required. Further, as a property required for filling the gap between the insert 1 and the inner wall of the mold, it is required that the insert article 1 has appropriate elasticity.

Examples of the treatment agent satisfying these conditions include a silicone rubber primer. Further, among the silicone rubber primers, (a) an organopolysiloxane having at least two aliphatically unsaturated hydrocarbon groups bonded to silicon atoms, and (b) an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms. Those containing siloxane, (c) reinforcing silica, (d) a platinum-based catalyst, and (e) a self-adhesive aid are preferred.

More specifically, an isocyanurate compound, an organosilicon compound having an epoxy group, an organosilicon compound having an acryloxyalkyl group and an alkoxy group, an alkoxysilane containing an alkenyl group, and an adduct of a hydrogensiloxane and an acrylalkoxysilane TSE322, TSE32
12, TSE3331, TSE3360 and the like manufactured by GE Toshiba Silicone Co., Ltd. can be mentioned as preferable examples.

FIG. 4 is a partially enlarged vertical sectional view of the vicinity of the injection molded portion of the insert 1.

As shown in FIG. 4, the surface of the insert 1 has small irregularities and is not uniform and flat.
When mounted in a mold, a gap is easily formed between the mold and an inner wall of the mold.

FIG. 5 is a vertical sectional view showing a state in which the above-mentioned treating agent is applied to the surface of such an insert 1 to form a treating agent layer P. As shown in FIG. 5, the upper surface of the treatment agent layer P forms a substantially even surface due to the action of surface tension. Next, the insert 1 on which the treatment agent layer P is formed is mounted in a mold (STEP.
2). FIG. 6 is a partially enlarged vertical cross-sectional view of the periphery of the injection target portion in a state in which the insert 1 on which the treatment agent layer P is formed is mounted in a mold. As shown in FIG. 6, the treatment agent layer P
Has successfully filled the gap between the upper surface of the insert 1 and the upper mold D1.

That is, the lower surface of the processing agent layer P is adhered to the upper surface of the insert 1, and the upper surface of the processing agent layer P is in close contact with the lower surface of the upper mold D1. At this time, since the lower surface of the upper mold D1 is a relatively uniform flat surface, while the upper surface of the insert 1 has irregularities, the upper mold D1
The gap between the lower surface and the upper surface of the insert 1 is not uniform. Therefore, even if the tightening strength between the upper mold D1 and the lower mold D2 is increased, the gap does not completely disappear.

Here, in the present invention, the gap between the lower surface of the upper mold D1 and the upper surface of the insert 1 is completely filled by the deformation of the treatment agent layer P. That is, the treating agent layer P is thick in the portion with a large gap, and the treating agent layer P is compressed and thinly deformed in the portion with a small gap. As a result, the lower surface of the upper mold D1 and the upper surface of the insert 1 are Completely seal the gap.

When the injection material is injected in this state, the injection material is supplied to the injection port d through an introduction path (a portion shown by a dotted line in the figure) provided in the upper mold D1 (STE).
P. 3) FIG. 7 shows this state.

The injection material supplied into the upper mold D1 is filled into the injection port d. On the other hand, since the bottom surface of the injection port d and its surroundings are completely sealed by the processing agent layer P, a seal portion S having a semicircular cross section is formed above the processing agent layer P. It does not flow into the gap between the lower surface of D1 and the upper surface of the insert 1. Therefore, the formation of burrs extending to the periphery of the seal portion S is prevented.

Next, when the insert 1 is removed from the mold (STEP. 4), the insert 1 is removed via the treating agent layer P.
An injection-molded article having the seal portion S formed on the upper surface is obtained. FIG. 8 is a vertical cross-sectional view in which the periphery of the injection target portion of the insert 1 removed from the mold is partially enlarged. As shown in FIG. 8, in the insert product 1 (injection molded product) after injection molding according to the present invention, the treatment agent layer P is disposed around the injection target portion of the insert product 1 as a base, and the processing agent layer P is formed thereon. The seal portion S is formed, and no burrs are formed. As described above in detail, in the injection molding method of the present invention, after the treatment agent is applied to the periphery of the to-be-injected part of the insert product 1, the insert product 1 is mounted and fixed in the mold, and the injection molding is performed. The treatment agent fills the gap between the mold and the insert 1 to prevent the injection material from flowing into this gap. Therefore, the formation of burrs formed when the injection material flows into the gap is prevented. Further, since the injection material does not flow into the gap, waste of the injection material is eliminated. Furthermore, since there is no generation of burrs, an extra step of a deburring step can be omitted.

Further, since it is not necessary to increase the clamping strength of the mold in order to reduce the gap between the mold and the insert 1, an abnormally high pressing force acts on the insert mounted in the mold. Since the pressing force does not occur, the insert product is not damaged by the pressing force, and the yield is improved.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the description has been made assuming that the treatment agent is in a liquid state, but may be in a paste state.

[0029]

According to the present invention, when performing the insert injection molding, the processing agent is applied beforehand around the portion to be injected of the base and then the injection is performed. Therefore, the processing material is formed between the base and the inner wall surface near the injection port of the mold. To prevent the injection material from flowing into this gap. As a result, the occurrence of burrs is prevented beforehand, so that deburring work becomes unnecessary and waste of the injection material can be prevented. Further, since it is not necessary to excessively increase the clamping strength of the mold in order to eliminate the gap between the inner wall surface of the mold and the substrate, breakage of the substrate due to the increase in the clamping strength is also prevented.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a flow of each step of an injection molding method according to the present invention.

FIG. 2 is a perspective view of an insert product constituting a base of the injection-molded product according to the present invention.

FIG. 3 is a plan view of an insert product constituting a base of the injection molded product according to the present invention.

FIG. 4 is a vertical sectional view around an injection-molded portion of the insert product according to the present invention.

FIG. 5 is a vertical sectional view of an insert product having a treatment agent layer formed on a surface thereof.

FIG. 6 is a vertical sectional view showing a state where an insert product is mounted in a mold.

FIG. 7 is a vertical sectional view showing a state where an injection material is injected into a mold.

FIG. 8 is a vertical sectional view of the insert product removed from the mold.

FIG. 9 is a vertical sectional view showing the inside of a mold when insert molding is performed by a conventional method.

[Explanation of symbols]

 D1 ... upper mold (mold), D2 ... lower mold (mold), 1 ... insert product (substrate), P ... treatment agent layer (primer layer).

Claims (7)

[Claims] 1. An insert injection molding method in which a base is fixed in a mold and an injection material is injected into an injection target portion of the base, wherein a process agent is applied to a periphery of the injection target of the base. An injection molding method, comprising: a step of mounting the base in a mold; and a step of injecting an injection material into the mold. 2. The injection molding method according to claim 1, wherein said base is a brittle material. 3. The injection molding method according to claim 2, wherein said base is made of ceramics, casting, glass, graphite, metal, or resin. 4. The injection molding method according to claim 1, wherein the treatment agent is a silicone rubber primer. 5. The injection molding method according to claim 4, wherein
The silicone rubber primer comprises (a) an organopolysiloxane having at least two silicon-bonded aliphatic unsaturated hydrocarbon groups, and (b) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms. And (c) a reinforcing silica, (d) a platinum-based catalyst, and (e) a self-adhesive auxiliary. 6. The injection molding method according to claim 1, wherein the injection molding material is a liquid silicone resin. 7. An injection-molded article comprising: a base; a primer layer formed on a surface of an injection portion of the base; and an injection material layer formed on the primer layer.