JPH07119026B2 - Primary molding product and method for producing two-color molding product using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a primary molded article and a method for producing a two-color molded article using the same.

[0002]

2. Description of the Related Art Conventionally, a resin mold having a display portion of characters, numbers, symbols, etc. on its surface has been used as a means for visually confirming input / output information like a key top which is an input medium of a keyboard or a typewriter. A two-color molded product that is a molded product is widely used.

In manufacturing this two-color molded product, first, a primary molded product having a display portion protruding from the upper surface is formed. Then, the two-color molded product such as a key top was obtained by integrally molding the secondary molded product so that the top surface of the display portion was exposed to the outside of the primary molded product.

By the way, in the case where there is a closed region which is closed and enclosed by the display unit inside the display unit, such as the number "0", the alphabet "D", and the code "Δ", It is necessary to inject the resin of the secondary molded body into the closed area. Therefore, a groove is formed from the periphery of the closed area to the back surface of the display section to reach the closed area,
The resin of the secondary molded body is injected into the closed area through this groove.

However, in the case where the primary molded body is molded with a light-transmissive resin and the impermeable secondary molding resin is injected into the closed region to illuminate the display section from the back side,
Since the secondary molded body having a lower light transmittance than the display portion is molded in the groove passing through the back of the display portion, that portion becomes a shadow and the display portion cannot be uniformly illuminated. there were.

In order to solve such a problem, for example, in Japanese Patent Laid-Open No. 62-279911, a resin is injected and molded through holes formed in the closed area of the display portion and the outside of the closed area. In addition, by cutting the protruding portion of the display portion formed between these holes to remove the outer shape member integrally molded below the protruding portion, there is a closed area in the display portion. Even 2
It has been proposed that a two-color molded product such as a key top can be obtained by enabling uniform display without the shadow of the next molded product being projected on the display unit.

[0007]

However, in the above-mentioned conventional example, an extremely small protruding portion must be cut at the final stage of two-color molding, which complicates the manufacturing process of the two-color molded product. There is. Therefore, according to the present invention, even if a closed area exists in the display unit, the display unit can be uniformly illuminated and a two-color molded product can be obtained by a simple process. The primary purpose is to provide a body and
A second object is to provide a method for producing a two-color molded product using the next molded product.

[0008]

In order to achieve the first object, according to the present invention, a gap serving as a display portion is formed by injecting a translucent resin and is surrounded by the gap. The primary molded body having a closed region is characterized by including a boss that straddles the gap and connects the peripheral region around the gap to the closed region.

In order to achieve the second object, according to the present invention, an outer die and an inner die are opposed to each other, and a resin is placed in a cavity formed between the outer die and the inner die. And a closed region surrounded by the gap is formed, and a peripheral region around the gap is connected to the closed region by straddling the gap. A first step of obtaining a primary molded body having a boss; and a secondary molding of the translucent resin into the primary molded body while injecting a transparent resin into the gap. The present invention relates to a method for producing a two-color molded article, which comprises a second step of applying a body.

[0010]

When the injection pressure for injecting the translucent resin for the secondary molded body is applied to the upper surface of the boss exposed in the gap, the boss is easily removed from the closed region and the peripheral region around the gap. Since the resin can be removed from the boss, the resin can be injected and the boss that shadows the display can be removed at the same time. As a result, a two-color molded product can be manufactured by a simple process. Become.

[0011]

EXAMPLES Next, examples of the present invention will be described. Figure 1
3 to FIG. 3 show a primary molded body of a key top, and a number “0” is drawn on the surface thereof.
1 is a plan view thereof, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a partial perspective view of a primary molded body.

In FIGS. 1 to 3, the primary molded body 10 has an open lower surface, is internally formed of a resin of a non-transmissive color with a low wall thickness and a constant wall thickness, and has a display on the surface thereof. A gap 12 is formed that defines a "0" as a part. Within the gap 12, a closed region 14 exists in a state of being surrounded by the gap.

The closed area 14 and a part of the peripheral area 16 are notched on the back side thereof into a rectangle 18, and the back surface 20 of the closed area and the back surface 22 of the peripheral area are covered with the closed area 14. Cylindrical boss 3 that connects to the peripheral region 16
0 extends over the gap 12 and is formed integrally with the primary molded body 10 toward the inside of the primary molded body 10. Therefore, by providing the boss 30, even if the closed region 14 is surrounded by the gap 12, the closed region 14 can be supported by the peripheral region 16 without falling off. The connecting area between the upper surface of the boss 30 and the back surface 20 of the closed area or the back surface 22 of the peripheral area is preferably limited to a relatively small value within a range in which the boss 30 does not fall off.

Next, a method of manufacturing a primary mold molded body 10 shown in FIGS. 1 to 3 and a two-color molded molded article using this primary mold molded body will be described. 4 to 6 are sectional views showing the manufacturing process. In FIG. 4, the outer mold 41, the inner fixed mold 44, and the inner movable mold 42 are opposed to each other, and the resin of the non-translucent color is not shown in the cavity formed between these molds. When poured from the gate, the primary molded body 10 shown in FIGS. 1 to 3 is formed. The outer mold 41 is provided with “0” for forming the gap portion 14 in the primary molded body 10.
-Shaped projections 46 are provided so as to project inward, and the projections 4 for forming the rectangle 18 are formed on the inner moving mold 42.
8 and a cylindrical recess 50 for forming the boss 30.
Are formed.

When the process of FIG. 4 is completed, the process moves to the process of FIG. In this step, the outer mold is replaced with the outer mold 41 having no protrusion 46, and the inner moving mold 42 is moved.
Back slightly. At this time, the space 51 corresponding to the movement amount of the inner moving mold 42 is formed in the outer mold 41 and the inner moving mold 4.
It is formed between the two. Next, the process proceeds to the step shown in FIG. 6, and the molten liquid of the translucent resin is injected into the space 51 from a pouring port (not shown). The injected translucent resin 52 is the space 5
1 and is applied to the back surface of the primary molded body 10 and is also filled in the gap 12 of the primary molded body 10. At this time, the injection pressure of the transparent resin is also applied to the upper surface of the boss 30 exposed in the gap 12 so that the boss 30 is pushed downward.

Since the connecting area between the upper surface of the boss 30 and the back surface 20 of the closed area or the back surface 22 of the peripheral area has a relatively small value, the injection pressure of the light-transmissive resin is increased.
When it is added to the upper surface of the boss 30, the boss 30 is separated from the closed region 14 and the peripheral region 16 and retracted to the inner moving mold 42.
Falls into the cylindrical recess 50.

By completing the process of FIG. 6, the primary mold molded body 10 made of an opaque resin as shown in FIG. 7 and the back surface of the primary mold molded body 10 are adhered, and A two-color molding in which a transparent resin is filled in the gap 12 and a secondary molding body having a display portion 56 that makes the numeral “0” stand out from the primary molding body 10 when light is transmitted is integrated. A molded product is obtained.

In such a two-color molded article, as shown in FIG. 8 which is a partial perspective view of the secondary molded article, the back surface of the closed region 14 in the gap is the secondary molded article. Since the translucent resin 52 is applied, the closed region is supported on the secondary molded body.

Since the boss 30 connecting the closed region and its peripheral region is released at substantially the same time as the press-in of the transparent resin melt, the step of cutting the boss can be eliminated.
Therefore, it becomes possible to inject the resin and remove the boss that shadows the display portion at a time, and the manufacturing process can be greatly simplified as compared with the conventional example. Further, in such a two-color molded product, the non-translucent boss 30 is separated, so that the entire display portion 56 can be formed without projecting a shadow on the translucent resin in the gap 12. Can be illuminated uniformly.

In this embodiment, the boss 30 has the closed area 1
4 so as to be separated from the peripheral region 16 and the peripheral region 16, the material of the primary molded body, the connection area between the boss 30 and the closed region 14 and the peripheral region 16, the injection pressure of the transparent resin, the injection of the transparent resin. At least one of the hour temperature and the like is preferably adjusted appropriately.

In this embodiment, as shown in FIG. 3, when the translucent resin for the secondary molded body is injected, the translucent resin advances in the gaps 12 in mutually opposite directions. , When the resin flows 60A and B in the opposite directions reach the side surface of the boss 30 and then rise along the side surface, and then collide with each other just on the upper surface of the boss, the colliding resin flow is directed toward the boss 30. It is preferable that the boss is surely detached because it is lowered substantially vertically to apply a larger pressure to the upper surface of the boss.

In the above embodiment, the back surface of the primary molded body is covered with the secondary molded body.
A configuration in which the secondary mold molded body is adhered to the surface of the primary mold molded body may be used. Further, although the boss is formed only at one place, it is also possible to form the boss at two or more places so that the closed region does not fall off. Further, in the above embodiment, the number "0" is used as the display unit having the closed area.
However, it goes without saying that the present invention can be applied to any character, symbol, code or the like having a closed region. Furthermore, in the above embodiment, the boss is formed on the back surface of the primary molded body, but the boss can be formed on the front surface side of the primary molded body.

[0023]

As described above, according to the present invention, the translucent resin is injected so that the peripheral region around the gap to be the display portion and the closed region surrounded by the gap straddle the gap. Since it has a boss that connects with,
Even if there is a closed region in the display unit, the excellent effect that the display unit can be uniformly illuminated and a two-color molded product that can be manufactured by a simple process can be obtained. it can.

[Brief description of drawings]

FIG. 1 is a plan view showing a primary molded body of a key top according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a partial perspective view of FIG.

FIG. 4 is a cross-sectional view showing a manufacturing process of the primary molded body.

FIG. 5 is a cross-sectional view showing a manufacturing process of a two-color molded product that comes in the next process of FIG.

FIG. 6 is a cross-sectional view showing a manufacturing process of a two-color molded product that comes in the next process of FIG.

FIG. 7 is a cross-sectional view of a two-color molded product obtained by the steps of FIGS.

FIG. 8 is a partial perspective view of a secondary molded body.

[Explanation of symbols]

 10 Primary Molded Body 12 Gap 14 Closure Area 16 Peripheral Area 30 Boss

Claims (2)

[Claims] 1. A primary molded body having a gap serving as a display portion formed by injecting a translucent resin, and having a closed region surrounded by the gap, the gap extending across the gap. A primary molded body comprising a boss that connects a peripheral region around the skirt and the closed region. 2. An outer mold and an inner mold are opposed to each other, and a resin is injected into a cavity formed between the outer mold and the inner mold to form a gap serving as a display portion, and A primary molded body having a closed region surrounded by the gap, and further comprising a boss that straddles the gap and connects the peripheral region around the gap to the closed region; 2 colors including a step 1 and a second step of injecting a translucent resin into the gap and depositing a secondary molded body made of the translucent resin on the primary molded body. Manufacturing method of molded article.