JPH11105083A - Mold structure for resin injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate air retention of a design surface completely by a method in which a permeable porous material is installed in a first mold, and an uneven part for reducing the glossiness of the design surface is formed on the surface of the porous material contacting the design surface of a resin part. SOLUTION: A cavity main body 3 and a core main body 4 are arranged to face each other, and a porous material 9 is embedded in the cavity main body 3. The material 9 is a gas permeable metal in which a kind of alloy powder and alloy short fibers are mixed and sintered, and numbers of fine vent holes are formed in the surface and the inside. The material 9 is formed in a prescribed shape which forms the design surface of a resin part 2 and functions as a part of a resin molding mold. Moreover, a fine uneven part 9a is formed on the design surface of the material 9. In this way, air or gas remaining between the design surface of the resin part and the first mold can be released into the air through the porous material 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin injection mold structure, and more particularly to a resin injection mold structure suitable for use as a resin part mold provided as an accessory of an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, resin parts are often used in parts around an instrument panel of an automobile or the like (for example, the instrument panel itself or an audio panel) in consideration of decorativeness, shock absorption, and the like. . In such a resin component, the texture is improved by reducing the glossiness of the surface as much as possible, and the reflection of light is reduced so that the driver's view is kept good.

As a method of reducing the glossiness, as shown in FIG. 4A, a fine uneven portion is directly formed on a mold 101 of a resin component 102 (hereinafter, such an uneven portion is referred to as a texture or a textured surface). ) 101a is formed in advance, and the
01a is transferred to the surface of the resin component 102 and the resin component 10
In general, a so-called textured surface 102a is formed on the surface of No. 2 to reduce the glossiness by dispersing the light reflection direction by the textured surface 102a.

[0004] As the resin part 102, for example, P
Resin materials such as PF (polypropylene with filler), PC / ABS (polycarbonate / acrylonitrile butadiene styrene), and PBT-G (polybutylene terephthalate with glass fiber) are often used.

[0005]

By the way, the mold 101
When the resin is injected into the mold 101, most of the air and gas existing in the mold 101 are separated by a minute gap between the core body and the mold body (refer to the reference numerals 3 and 4 in FIG. 1). However, since the resin is injected at a high pressure in a short time, a part of the air or gas remains inside as shown in FIG. An air pocket may occur during the operation.

[0006] When air accumulation occurs as described above, the mold 1
Thus, the adhesion between the mold 101 and the resin 102 is reduced, and the transferability of unevenness (texture) from the mold 101 to the resin 102 is also reduced. When the transferability of the grain is reduced, the surface of the resin component 102 becomes relatively smooth as shown in FIG. 4B, and the glossiness is increased.

[0007] Therefore, conventionally, after forming the resin component 102, mat coating is required, which has increased the component cost. In addition, when the above-described air pool occurs, the fluidity of the resin in the mold 101 decreases,
A flow pattern (flow mark) may be generated on the surface of the resin, or a weld line may be generated at a portion where the resins injected from different resin injection holes provided in the mold 101 merge. Since such weld lines and flow marks cause deterioration in the quality of the resin component 102, matte coating is required to erase such weld lines and flow marks.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 1-259914 discloses a method in which a porous permeable material is provided in a molding die and air or gas in the mold is removed from the porous permeable material. There is disclosed a technology that discharges outside the mold via a. However, in the above technology, the porous permeable material is disposed at a position on the back side of the resin component, and the air trap generated between the design surface of the resin component and the mold surface facing the resin component is completely eliminated. There is a problem that it cannot be removed. Therefore, the transferability of the unevenness (texture) cannot be expected to be much improved, and again, there is a problem that it is necessary to paint the resin component after molding.

The present invention has been made in view of the above problems, and completely eliminates air pockets on the design surface of a resin component to improve the transferability of irregularities (textures) on a mold and to reduce extraneousness. It is an object of the present invention to provide a resin injection molding die structure capable of eliminating a matte coating of various resin parts.

[0010]

According to the first aspect of the present invention, there is provided a resin injection mold structure, wherein a first mold forms a design surface of a resin part and a second mold forms a resin part. The back side of the part is formed. Then, at the time of molding the resin, air and gas between the design surface of the resin component and the first mold are discharged to the outside via the porous material provided in the first mold. As a result, the concave and convex portions formed on the surface of the porous material that comes into contact with the design surface of the resin component adhere to the resin component being molded, and the glossiness of the molded resin component is reduced.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the overall structure of a resin injection mold according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a mold, 2 denotes a resin molded product (or also referred to as a resin part), and 3 and 4 denote a mold body (first mold) and a core body (first mold) which constitute main parts of the mold 1, respectively. Second mold), 5 is an ejector pin, 6 and 7 are mounting plates,
8 is a resin injection hole, 9 is a porous material (porous mold) having air permeability, and 10 is an air discharge hole.

Here, the mold body 3 is a mold for forming the design surface shape of the resin part 2, and the core body 4 is a mold for forming the back side shape of the resin part 2. 4 are arranged so as to face each other. Further, as shown in FIG. 1, a porous material 9 is embedded in the mold body 3. The porous material 9 is a gas-permeable metal obtained by mixing and sintering alloy powder and alloy short fibers, and has a large number of fine air holes (not shown) formed on the surface and inside thereof.

The porous material 9 is formed in a predetermined shape so as to form a design surface of the resin component 2, and functions as a part of a resin molding die. Hereinafter, the porous material 9 is also referred to as a porous mold as needed. As shown in FIG. 3 (a), the design surface of the porous mold 9 has fine irregularities (texture surface) 9a similar to a normal mold.
Are formed on the surface of the resin component 2 so as to form the texture 2 a on the resin component 2.

On the other hand, as shown in FIG. 1, an air discharge hole 10 is formed inside the cabinet body 3, and the air discharge hole 10 is connected to the porous mold 9. As a result, air or gas remaining between the surface of the resin component 2 and the mold body 3 at the time of injection molding of the resin is discharged to the atmosphere through the air holes and the air discharge holes 10 in the porous mold 9. It has become.

Therefore, a so-called air pocket (FIG. 4) is formed between the surface of the resin component 2 and the mold body 3 at the time of molding the resin.
(A) is suppressed, and the porous mold 9
Thus, the shape of the textured surface 9a formed on the surface of the resin component 2 can be reliably transferred to the surface of the resin component 2, thereby reducing the glossiness of the resin component 2. In addition, by suppressing the occurrence of air pockets, the fluidity of the resin in the mold 1 is improved, and the occurrence of flow patterns (flow marks) and weld lines can be suppressed.

When forming irregularities (textures) on a normal mold, first, a special sheet on which a texture is formed and a photosensitive agent are first adhered to the mold. It is common practice to irradiate light on the surface of the substrate to form irregularities with a photosensitive agent, and then corrode the portions corresponding to the concave portions with an acidic solution.
, The solution permeates the porous mold 9 through the air holes.

Therefore, in the air-permeable mold 9 according to the present invention, the embossed surface 9a is formed as described below in order to prevent the solution from penetrating into the inside. First, the air-permeable mold 9 is impregnated with a resin having heat resistance. Note that this resin has a performance capable of withstanding heat up to about 300 ° C., for example. After that, the grain surface 9a is formed in the same manner as in a normal mold. In this case, since the ventilation holes of the mold 9 are closed with the resin, the textured surface 9 a is formed on the surface of the gas permeable mold 9 without the solution penetrating into the gas permeable mold 9.

Finally, the air-permeable mold 9 is placed in a solvent (for example, an acetone solvent) and subjected to ultrasonic cleaning to remove the heat-resistant resin impregnated in the mold 9. Thereby, the solution does not penetrate into the air permeable mold 9,
The textured surface 9a can be formed on the surface of the air permeable mold 9. The textured surface 9 formed on the air-permeable mold 9
The irregularities in a are the ventilation holes (for example, 7 μm in diameter) of the ventilation mold 9.
m), and the molten resin does not flow into the air holes during resin molding.

Since the resin injection mold structure according to one embodiment of the present invention is configured as described above, the resin component 2 is subjected to injection molding, for example, according to the procedure shown in FIG.

First, as shown in FIG. 2 (a), the cabinet body 3 and the core body 4 which are located opposite to each other are
As shown in (b), the mold is clamped in close contact (mold clamping step). Next, as shown in FIG. 2C, the molten resin is injected into the mold 1 from the resin injection hole 8 of the mold body 3, and the pressure and cooling are performed for a predetermined time (injection, pressure holding, and cooling). Process). In this step, when the resin is injected into the mold 1, a part of the air and gas in the mold 1 is discharged from a slight gap between the mold body 3 and the core body 4. Also,
Of the remaining air and gas, the air and gas remaining between the resin component 2 and the cabinet body 3 are formed in fine ventilation holes (not shown) formed in the permeable mold 9 and the cabinet body 3. The air is discharged to the atmosphere through the air discharge holes 10.

Therefore, as shown in FIG. 3 (a), the surface of the resin component 2 is in close contact with the textured surface 9a formed on the surface of the air-permeable mold 9, so that the shape of the textured surface 9a is ensured. Will be transcribed. Finally, as shown in FIG.
Separating the mold body 3 from the core body 4 (mold opening step)
Next, the molded resin part 2 is extruded using the ejector pin 5 and taken out (product take-out step). By repeating the above-described steps, the resin component 2
Are sequentially manufactured.

As described above, according to the resin injection mold structure of the present invention, the air and gas remaining between the resin component 2 and the cabinet body 3 are removed by the fine air-permeable mold 9. As shown in FIG. 3 (a), the mold 1 (particularly the air-permeable mold) is formed at the time of resin molding, because the air is released to the atmosphere through a ventilation hole (not shown) or an air discharge hole 10 formed in the cabinet body 3. 9) and the resin component 2 (especially, the design surface of the resin component 2) have improved adhesion, and the surface of the resin component 2 has a textured surface 9a of the air-permeable mold 9.
Can be reliably transferred.

Therefore, as shown in FIG. 3B, the surface of the resin component 2 becomes rough, the light reflection direction is dispersed, the glossiness is reduced, and the texture is improved. In addition, the reflection of light from the resin component 2 is reduced, so that the visibility of the driver can be kept good, and the trouble of the driver can be suppressed. In addition, such a resin component 2
If this is the case, there is an advantage that matte coating after resin molding, which was conventionally required, can be eliminated, and costs can be significantly reduced.

Further, since the air and gas in the mold 1 are efficiently discharged to the outside, the fluidity of the resin in the mold 1 is improved, and there is an advantage that the generation of flow marks and weld lines can be suppressed. is there. In particular, even if the flow distance and flow time of the resin are relatively long, such as a speaker grill formed in a mesh pattern as a decorative part, the flowability of the resin at the time of molding is improved. There is an advantage that generation of a weld line can be suppressed.

Further, since the air-permeable mold 9 is a member provided in the mold (cab body) 3, the embossments 9a can be changed according to the type of the resin component. In addition, the ventilation mold 9 can be easily replaced.

In FIG. 3, the textured surfaces 2a, 9
Although the textures 2a and 9a are schematically drawn in order to easily express a, the textured surfaces 2a and 9a are not of such a size, but are actually formed as minute irregularities. The textured surfaces 2a and 9a are not formed in such a simple shape, but are formed into irregular irregularities in order to disperse the reflection of light.

The resin injection mold structure of the present invention is not limited to the above embodiment.
Various modifications are possible without departing from the spirit of the present invention.

[0028]

As described in detail above, according to the resin injection mold structure of the present invention, the simple structure as described above allows the space between the design surface of the resin component and the first mold. Residual air and gas can be released to the atmosphere through the porous material, which improves the adhesion between the first mold and the design surface of the resin component during resin molding, and improves the surface of the resin component. In addition, there is an advantage that the uneven portion formed on the porous material can be accurately transferred. As a result, the glossiness of the resin component can be reduced and the texture can be improved. Further, the reflection of light from the resin component is reduced, so that the visibility of the driver can be kept good, and the driver does not have to worry about the reflection of light.

Further, since the air and gas in the mold are discharged to the outside, there is an advantage that the fluidity of the resin in the mold is improved, and the occurrence of flow marks and weld lines can be suppressed. In addition, such a resin component has the advantage that matte coating after resin molding, which was conventionally required, can be eliminated, and the cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining the entire configuration of a resin injection mold structure according to an embodiment of the present invention.

FIGS. 2A to 2E are diagrams for explaining a resin molding process using a resin injection mold structure according to an embodiment of the present invention.

FIGS. 3A and 3B are schematic diagrams for explaining main parts and functions of a resin formed by applying a resin injection mold structure according to an embodiment of the present invention; FIGS. .

4 (a) and 4 (b) are schematic views for explaining a main part and operation of a resin formed by applying a conventional resin injection molding die structure, respectively. a),
It is a figure corresponding to (b).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mold 2 resin molded product (or resin part) 2a uneven portion (textured surface) 3 mold body (first mold) 4 core body (second mold) 8 resin injection hole 9 porous material (porous) Mold) 9a Uneven part (textured surface) 10 Air exhaust hole

Claims (1)

[Claims] 1. A resin injection mold structure comprising a first mold for forming a design surface of a resin part and a second mold for forming a back surface of the resin part, wherein the first mold is provided. A porous material having air permeability is provided in the mold, and a surface of the porous material in contact with the design surface of the resin component,
A resin injection molding die structure, characterized in that irregularities are formed to reduce the glossiness of the design surface of the resin component.