JPH0939029A - Surface treatment of synthetic resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with skill because processing is not applied to a base part and no painting is applied when welding is eliminated and to prevent the pollution of global environment. SOLUTION: In a method for the surface treatment of the cover part of a synthetic resin molded product capable of generating welding based on the generation of a fine cavity on the surface thereof, the cover part C on the surface of the base part of the synthetic resin molded product is set to a three- color mold 23 and a cover layer E composed of a transparent synthetic resin is integrated with the surface thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for a synthetic resin molded product, which eliminates welds caused by the generation of fine depressions on the surface of the synthetic resin molded product.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, an air conditioner control operation panel 1 is constructed by mounting a molded product 3 as an operation button part on a frame part 2. The air conditioner control operation panel 1 and the molded product 3 are formed by injection molding a synthetic resin such as ABS as a surface layer, and are integrated with each other in the assembling process, and then assembled into the air conditioner control operation unit body. These air conditioner control operation panel 1,
The molded product 3 is provided with a display pattern P for displaying functions such as polycarbonate or polyacetal from the back side so that it can be visually recognized by an occupant such as a driver. In the case of the two-color molding method, the air conditioner control panel 1 and the molded product 3
The display pattern P may be provided by a method such as printing.

In FIG. 3, as an example, the operation button 3a for setting the foot blowing mode is enlarged. The molded product 3 such as the operation buttons 3a is manufactured by two-color molding in order to indicate the display pattern P.

That is, as shown in FIG. 4, a base portion B is formed by injecting a molten synthetic resin such as white through a gate 7 into a molding space 6 of a first mold composed of a core 4 and a cavity 5. Mold. At this time, a protruding portion B2 corresponding to the display pattern P is formed on the front surface B1 side of the base portion B.

Next, as shown in FIG. 5, after the core 4 having the above-mentioned base portion B mounted therein is combined with the cavity 10 constituting the second mold, injection molding is performed via the gate portion 11. The cover portion C is molded by injecting, for example, a black molten synthetic resin having a color tone different from that of the base portion B into the space J. In this case, in the injection molding space J, the tip surface of the protruding portion B2 is previously covered with the cover portion C.
It is set so that it can be seen from the front face C1.

According to the molded product 3 molded by the two-color molding using the first and second molds, the protruding portion B2 of the base portion B can be seen from the front surface C1 of the cover portion C. Therefore, the display pattern P can be clearly displayed due to the difference in contrast between the base portion B and the cover portion C.
In addition, unlike the case where the display pattern P itself is formed by painting, it becomes difficult to visually recognize it due to abrasion.

However, according to this, when molding the second color shown in FIG. 5, as shown in FIG. 6, when the melt molding resin for molding the cover C is injected from the gate 11, the base B is projected. A weld 20 is generated on the front surface C1 of the cover portion C on the side of the portion B2 opposite to the gate 11.

As shown in FIG. 7 (a), the weld 20 has a finely recessed front surface C1 of the cover portion C, and when the melt-molded resin is injected from the gate 11 as shown in FIG. Projection B2 as seen from the gate 11
By joining the melt-molded resin on the opposite side of
It occurs as wrinkles.

As a conventional example attempting to overcome this problem, for example, the technique disclosed in Japanese Utility Model Laid-Open No. 63-72619 is known. This is characterized by thinning the thickness of the center of the base far away from the gate and gradually increasing the thickness on both sides of the base. The generation of welds is suppressed by increasing the outflow speed of.

As another conventional example, as shown in FIG. 7B, a transparent layer 30 is formed on the entire front surface C1 of the cover C by painting so that the surface of the transparent layer 30 reflects light. The weld 20 was made inconspicuous. In this way, when the transparent layer 30 is formed on the entire front surface C1 of the cover part C by painting, as shown in FIG. 7B, the light is totally reflected on the surface of the transparent layer 30 and the presence of the weld 20 can be visually recognized. Disappear.

[0011]

[Problems to be Solved by the Invention]
In the conventional example disclosed in Japanese Patent Laid-Open No. 9-93, after all, since it is necessary to form a concave portion on the core side or a convex portion on the cavity side, a core or cavity for manufacturing a fine synthetic resin molded article There are structural limitations to applying to. That is, since it is a method of forming a concave portion such as a V-shaped groove in the base portion B, it is very difficult to apply it to the base portion B having a small thickness from the beginning, or the occurrence of welds is suppressed. In some cases, a V-shaped groove having an appropriate size cannot be formed, and the effect of suppressing the occurrence of welds cannot be obtained at all. On the other hand, the transparent layer 30 is formed on the entire front surface C1 of the cover C by painting.
In the case of adopting the method of applying the method, not only does it require manual labor by hand and requires skill, but it is not very good for the global environment.

The present invention has been made in view of the above problems, and does not require any modification to the base portion on which the display pattern is formed, requires no skill, and is harmful to the global environment. It is an object of the present invention to provide a surface treatment method for a synthetic resin molded article, which can surely and inexpensively eliminate welds by a method that does not affect the temperature.

[0013]

According to the first aspect of the present invention,
In a surface treatment method for a synthetic resin molded product, which may cause welds due to the generation of fine depressions on the surface, the synthetic resin molded product is set in a three-color molding die, and a transparent synthetic resin cover layer is integrated on the surface. It is characterized by having done.

According to a second aspect of the present invention, the synthetic resin molded article in which the weld can be formed is formed by integrally forming the base portion and the cover portion by two-color molding, and a part of the base portion is more than a part of the cover portion. It is characterized in that a display pattern is formed by projecting through.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view illustrating an embodiment of a surface treatment method for a synthetic resin molded product according to the present invention. The embodiment of the present invention may be applied to the molding of the air conditioner control operation panel 1 described in the related art, but the description thereof is omitted here, and the operation button 3a used for the air conditioner control operation panel 1 is omitted. The surface treatment method will be described as an example.

The method of molding the operation button 3a is the same as the conventional method. To explain once again, that is, as shown in FIG. 4, by injecting a molten synthetic resin such as white into the molding space 6 of the first mold including the core 4 and the cavity 5 through the gate 7 The base part B is molded. At this time, the display pattern P is provided on the front surface B1 side of the base portion B.
The protrusion B2 corresponding to is formed.

Next, as shown in FIG. 5, after the core 4 to which the above-mentioned base portion B is attached is combined with the cavity 10 constituting the second mold, the base portion is inserted through the gate portion 11. The cover portion C is molded by injecting, for example, a black molten synthetic resin having a color tone different from that of B. In this case, the injection molding space J has the protrusion B in advance.
The front end surface of 2 is set so as to be seen from the front surface C1 of the cover portion C.

According to the molded product 3 molded by the two-color molding using the first and second molds as described above, the protrusion B2 of the base B is molded by looking into the front surface C1 of the cover C. Therefore, the display pattern P can be clearly displayed due to the difference in contrast between the base portion B and the cover portion C, and the display pattern P itself is hard to be visually recognized due to abrasion unlike the one formed by painting. It will not occur.

Then, as shown in FIG. 1, the core 4 with the base portion B mounted by, for example, mechanical means is combined with the cavity 23 constituting the third mold, and then the gate portion 25 is interposed. The surface of the cover C and the cavity 2
A transparent cover layer E is molded by injecting a transparent synthetic resin into the molding space between the cover 3 and the mold 3. In this case, the transparent cover layer E is integrally molded so as to cover almost the entire surface of the cover portion C.

According to the molded article molded by three-color molding using the first, second, and third molds, that is, the display button 3a, the transparent cover layer E molded on the surface of the cover portion C is used.
Is transparent, so that the protrusion B2 of the base portion B is molded by looking through the front surface C1 of the cover portion C, that is, the contrast is clearly displayed due to the contrast difference between the base portion B and the cover portion C. It does not hinder the visual recognition of the display pattern P at all.

Further, 3 using the first, second and third molds
According to the molded product formed by color molding, that is, the display button 3a, since the transparent cover layer E formed on the surface of the cover portion C is transparent, light is totally reflected on the surface of the transparent cover layer E. Make the presence of welds invisible.

In the above-mentioned surface treatment method for the synthetic resin molded product, in order to eliminate the weld of the cover portion C, it is not necessary to add any processing such as forming a groove in the base portion B which constitutes the display pattern P. Therefore, there is no problem in molding a small synthetic resin molded product. In addition, it is a clean surface treatment method that requires no skill because it does not require painting, etc. and does not harm the global environment. In addition, since mechanization, that is, automation, is possible, mass production can be performed reliably and easily, and welds can be eliminated at low cost.

FIG. 2 is a perspective view showing an example of a three-color molding die used in the embodiment of the present invention. In the three-color molding die 31, the one side surface is opened 120 degrees from the center, the positions are equidistant from each other, and the outer sides are 120 degrees from the center.
A primary core 33a, a secondary core 33b, and a tertiary core 33c that are arranged in the direction of the degree are provided. Mold 3
For example, when 1 rotates 120 degrees to the left, the primary core 33a becomes 2
It is located at the position of the secondary core 33b, and similarly, the secondary core 33b
Is located at the position of the tertiary core 33c, and similarly, the tertiary core 3c
3c is located at the position of the primary core 33a.

The three-color molding die 41 corresponds to the primary, secondary, and tertiary cores 33a, 33b, and 33c, and is located at a position 120 degrees apart from the center of one side and at equal intervals from the center. , The primary cavities 43, the secondary cavities 45, 3 which are respectively arranged 120 degrees outward from the center
A secondary cavity 47 is provided. In the case of this embodiment, the three-color molding die 41 does not rotate and is fixed, the three-color molding die 31 moves back and forth in the direction of the three-color molding die 41, and
It rotates intermittently every degree.

Next, a surface treatment method for a synthetic resin molded product using the three-color molding dies 31, 41 will be described. In this description, first, the molding by the primary core 33a will be mainly described. First, as a first step, a two-color molding die 31,
41 and the primary core 33a and the primary cavity 43
The secondary core 33b and the secondary cavity 4
5, the tertiary core 33c and the tertiary cavity 47 are also integrated). Then, a molten synthetic resin such as white is injected into the molding space between the primary core 33a and the primary cavity 43 through a gate (not shown) to form a base portion B.
Is molded. At this time, a protruding portion B2 corresponding to the display pattern P is formed on the front surface B1 side of the base portion B.

Thereafter, in a second step, the three-color molding die 31 is separated from the three-color molding die 41 and the three-color molding die 31 is rotated 120 degrees to the left (at this time, 1 The solidified base portion B is still attached to the next core 33a, and the three-color molding dies 31 and 41 are combined again to combine the primary core 33a and the secondary cavity 45 (note that 2
The secondary core 33b and the tertiary cavity 47, the tertiary core 33c and the primary cavity 43 are also integrated). Then primary core 3
In the molding space between 3a and the secondary cavity 45, actually in the molding space between the base portion B mounted on the primary core 33a and the secondary cavity 45, the base portion B is separated from the molding space through a gate (not shown). The cover portion C is molded by injecting, for example, a black molten synthetic resin having a different color tone. In this case, the injection molding space is set in advance so that the tip end surface of the protruding portion B2 can be seen from the front surface C1 of the cover portion C.

Then, in a third step, the three-color molding die 31 is separated from the three-color molding 41 and the three-color molding die 31 is rotated 120 degrees to the left (at this time, the primary The solid cover portion C is still attached to the base portion B on the core 33a, and the three-color molding dies 31 and 41 are united again, and the primary core 33a and the tertiary cavity 47 are united. The secondary core 33b and the primary cavity 43, the tertiary core 33c and the secondary cavity 45 are also integrated). Next, in the molding space between the primary core 33a and the tertiary cavity 47, actually, in the molding space between the cover portion C on the surface of the base B mounted on the primary core 33a and the tertiary cavity 47, not shown. A transparent cover layer E is formed by injecting a transparent synthetic resin through a gate. In this case, the transparent cover layer E is integrally molded so as to cover almost the entire surface of the cover portion C.

Thereafter, when the three-color molding die 31 is separated from the three-color molding die 41 and the molded product is removed from the primary core 33a, a display button 3a having a transparent cover layer E on its surface is obtained. be able to. Also in this case, the weld cannot be visually recognized from the display button 3a having the transparent cover layer E. The above is a description of the primary core 33a, but the secondary core 33b and the tertiary core 33c are also sequentially the primary cavity 43, the secondary cavity 45, 3
The same molded product is manufactured by repeating the combination with the next cavity 47 and the separation, and simultaneously performing the injection in this process.

In the three-color molding dies 31 and 41, the first step, the second step, and the third step as described above are simultaneously performed for the secondary core 33b and the tertiary core 33c, respectively. Therefore, it is extremely suitable for mass production.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention.

FIG. 2 is a perspective view illustrating an example of a mold used in the embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a specific example of a conventional synthetic resin molded product.

FIG. 4 is a sectional view illustrating a part of a conventional method for manufacturing a synthetic resin molded product.

FIG. 5 is a cross-sectional view illustrating a part of a conventional method for manufacturing a synthetic resin molded product.

FIG. 6 is an explanatory diagram illustrating a situation of occurrence of welds.

FIG. 7 is an explanatory diagram illustrating a state of a weld and a weld elimination example.

[Explanation of symbols]

 B Base part C Cover part E Cover layer 3 Molded product 3a Operation buttons 21, 23 Mold 25 Gate.

Claims (2)

[Claims] 1. A method for treating a surface of a synthetic resin molded product, which can cause welds due to the generation of fine depressions on the surface, wherein the synthetic resin molded product is set in a three-color molding die, and a transparent synthetic resin is formed on the surface thereof. A surface treatment method for a synthetic resin molded article, characterized in that a cover layer is integrated. 2. The synthetic resin molded product in which the weld may occur is formed by integrally forming a base part and a cover part by two-color molding, and is displayed by partially protruding the base part from a part of the cover part. The surface treatment method for a synthetic resin molded article according to claim 1, wherein the surface treatment method comprises forming a pattern.