JPH11268077A - Plastic molded product and molding thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a sink mark on a surface at a time of injection molding and the deformation or shape collapse on the surface caused by the deformation of a rear surface. SOLUTION: A plastic molded product having an one layer structure usually molded by one injection molding is formed into a twolayered structure consisting of surface member 2 having decoration applied to the surface layer thereof and a rear member 3 having a projected part 6 formed on the rear surface thereof and the surface member 3 is molded as a second mold by first injection and the surface and rear members 2, 3 are integrated by second injection molding for molding the surface member 2 as a second mold by second injection. Since the wall thickness difference between the surface and rear members 2,3 is extremely slight even if a sink mark is developed on the surface 3a of the already molded rear molded member or the rear member 3 is slightly deformed, when the surface member 2 is superposed to perform molding, it is prevented that unevenness is formed on the surface 2a or the shape collapse of the surface member 2 is brought about.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molded product in which a projection such as a mounting projection is formed on the back surface side with respect to the front surface side to be decorated, and a molding method therefor. It is suitable for use in injection molding of parts and the like.

[0002]

2. Description of the Related Art Recent automobile parts include a lighter body,
Due to the advantages of improved durability and functionality of parts, freedom of shape, and cost reduction, plasticization has rapidly progressed, and with that, the demand for decoration on plastic parts has also increased significantly. It is of a very high level.

[0003] In particular, as for interior parts, plastic molded products are used, such as instrument panels, console boxes, door trims, steering wheels, and handles, and these molded products have a mere coloring level. It is required to give a high-class decoration such as an exceedingly grained pattern or a marble pattern. In addition, as plastics used as materials for these molded products, there are thermosetting ones and thermoplastic ones, but the former is difficult to recycle as waste plastic and is not preferable from the viewpoint of environmental conservation. Therefore, thermoplastic materials tend to be often used.

FIG. 4 shows, for example, an interior part used as a switch box mounted inside a door of a driver's seat, in which mounting holes 31... The grip forming recess 32 is formed to be open. The front side (the surface visible from the room) 33 is decorated with a grain pattern or the like, and the rear side 34 is provided with not only the screw hole forming projections and the fitting projections but also the door grip forming recesses 32. These are also formed as the protruding portions 35. When molding such an interior part, after injecting plastic by injecting plastic into a cavity formed between the clamped molds, the mold is opened and the molded product is taken out, and the molded product is taken out. Decorations.

[0005]

However, when such an interior component is injection-molded, there is a problem in that uneven sink marks M appear on the surface side 33 to be decorated. This causes a volume shrinkage difference called sink mark due to non-uniform cooling of the resin filled in the cavity or the like, thereby causing a product defect in which the surface becomes uneven, and is likely to appear in a portion having a wall thickness difference. The interior parts and the like of this example have a projection 3 such as a screw hole formation projection formed on the back side 34 thereof.
5 is locally thicker than the other smooth surfaces 30, the amount of shrinkage of the protruding portion 35 increases by the thickness, and the effect becomes uneven on the surface side 33. It is thought to appear. If the mold is removed after the molding die has been sufficiently cooled, the sink mark M is unlikely to appear, but if the cooling is performed over a long period of time, there arises a problem that the production efficiency is reduced.

In addition, the concave portion 32 for forming the door grip is
Even if it protrudes greatly on the back side 34 of the smooth surface 30, it is not itself thick, and since the smooth surface 30 is also open, no sink marks appear, but the deformation in the depth direction and the circumferential direction is compared. Due to the large size, there is a problem that the smooth surface 30 is easily distorted or deformed due to the deformation.

In addition, when decorating a wood grain pattern on the front side 33 by a liquid pressure transfer method, a transparent transfer film having a wood grain pattern printed with black (dark brown) ink is attached to the brown colored front side. If the ink is not transferred by attaching it on the surface 33, a wood grain pattern is not obtained. And the front side 3
In order to make 3 a brown color, a case in which the resin is mixed with a brown pigment and a case in which the surface side 33 is painted in a brown color can be considered. In this case, most of the color of the recycled plastic obtained by recycling the waste plastic is black or gray. Therefore, in order to make the resin brown, it is necessary to mix a brown pigment after bleaching (bleaching). Also, when painting with a brown paint, the cost is lower than making the resin itself brown, but a painting process is required between the injection molding process and the decorating process, and in the painting process, simply painting In addition, since a painting operation and a drying operation are required, the number of processes and equipment are increased by that amount, which also leads to an increase in cost.

Accordingly, the present invention is to prevent sink marks from appearing on the front side when injection molding is performed, prevent deformation on the front side due to deformation on the back side, and lose shape. It is an object of the present invention to eliminate the step of painting the base color on the front side when the decoration is applied.

[0009]

In order to solve this problem, the present invention relates to a plastic molding method in which a projection such as a screw hole forming projection is formed on the back side with respect to the front side to be decorated. Product, the surface member is decorated on the front surface side, the back surface side has a two-layer structure of the back member formed with the protruding portion, one member of the front member and the back member After being molded as a first mold, both the front member and the back member are integrated by double injection molding in which the other member of the front member and the back member is formed by being overlapped with the first mold. .

[0010] The plastic molded article of the present invention is a single-layer structure molded by ordinary single injection molding, comprising a front member having a decoration on the front side, and a back surface having a projection formed on the rear side. The member had a two-layer structure. And, for example, 1
The back member is formed as a first mold by the second injection, and the front member and the back member are integrated by the second injection molding in which the front member is formed as a second mold by the second injection.

In this case, since the front member is formed as the second mold on the back member already formed as the first mold, a sink mark appears on the front side of the back member or the back member is slightly deformed. Even so, the sink mark and the deformed portion are covered with the surface member. Further, since the difference in wall thickness due to the sink mark and the deformation of the back surface member is extremely small, this does not appear as unevenness on the surface of the front surface member, and does not lead to the deformation of the front surface member.

Further, for example, when decorating a wood grain pattern on the front side by a hydraulic transfer method, if the back surface member is formed of recycled plastic and only the front surface member is formed of brown plastic, all of the surface member is formed of brown plastic. The cost is lower than in the case of molding, and the surface is colored brown at the time of completion of the injection molding, so that there is no need for any painting process for painting the base color.

[0013]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a perspective view showing the structure of a plastic molded product according to the present invention, FIG. 2 is a sectional view thereof, and FIGS. 3 (a) to 3 (d) are process diagrams showing a molding method thereof.

The plastic molded article 1 of the present embodiment is a switch box mounted inside a door of a driver's seat as an interior part for an automobile, and is decorated with a grain pattern or the like on a front side 2a by a hydraulic transfer method. The rear member 3 has a two-layer structure of a front member 2 to be formed and a rear member 3 in which protrusions 6 such as screw hole forming projections 4 and 4 and a door grip forming recess 5 are formed on the rear surface 3b. Is covered with the surface member 2.

The surface member 2 is formed in a smooth plate shape with a small difference in thickness as a whole, with some irregularities, and a switch mounting hole 8 for mounting various switches such as an automatic door lock and a window opener. , Back member 3
Top opening 5 of door grip forming recess 5 formed in
An opening 9 communicating with a is formed. The back plate 3 has a shape in which the thin plate portion 10 connecting the screw hole forming projections 4 and 4 and the door grip forming recess 5 projecting from the back surface 3b is hidden by the back surface 2b of the front member 2. Is formed. Here, the front member 2 and the back member 3
Is integrated by, for example, two injection moldings in which the back member 3 is formed as a first mold, and then the front member 2 is formed thereon as a second mold.
Finally, a transfer film on which a wood grain pattern or a marble pattern is printed with ink 11 is adhered to the surface side 2a of the surface member 2 of the plastic molded article 1 thus formed by a hydraulic pressure transfer method. Is transferred and decorated.

The above is one example of the plastic molded product according to the present invention. Next, as for the molding method, the back member 3 is used as the first mold and the front member 2 is used as described above.
For example, when molding as a second mold,
A specific description will be given based on FIGS. FIG.
In the injection molding apparatus 20 shown in FIG.
By the rotation of the rotor 21, it has been made to stop at the primary injection position P ₁ and the second injection position P _2.

At the first injection position P ₁ , a first mold 23 that is fastened to the back mold 22 and a cavity 24 formed between the molds 22 and 23 are melted. A primary injection device 25 for injecting plastic to form the back member 3 is provided. Also,
The second injection position P _2, the second molding die 26 which is the rear surface member 3 is first molded clamping and back molding die 22 in the primary injection position P _1, the back side member 3 and the second mold A secondary injection device 28 that injects molten plastic into the cavity 27 formed between the molding dies 26 to form the surface member 2 is provided.

When the plastic molded article 1 is molded by injection molding twice using the injection molding apparatus 20, first, the back member 3 is molded in a first injection step,
In the second injection step, the surface member 2
To integrate them. The primary injection step, as shown in FIG. 3 (a), a primary injection position P ₁ on the back surface molding die 22 and the first molding die 23 by clamping, each mold 22, 23 As shown in FIG. 3B, the primary injection device 2 is provided in the cavity 24 formed therebetween.
By 5, for example, a black recycled plastic is injected to form the back member 3 by injection molding. Then, as shown in FIG. 3C, the mold is opened, and the rotor 21 is not removed from the back molding die 22, and the rotor 21 is rotated 180 degrees as shown in FIG.
° rotated, as shown in FIG. 3 (a), rotating the die 22 to the second injection position P ₂ facing the second molding die 26.

Next, in the second injection step, as shown in FIG. 3A, a second mold 26 is clamped to the back mold 22 at a second injection position P ₂ . FIG.
As shown in (b), a secondary injection device 28 injects, for example, brown plastic into a cavity 27 formed between the back surface member 3 and the second mold 26 so that the top surface of the back surface member 3 Then, the surface member 2 to be a second mold is injection-molded. As a result, the plastic molded product 1 in which the front surface member 2 is integrated on the back surface member 3 is formed. The mold is opened as shown in FIG.

In this case, the back surface member 3 formed in the first injection step has the projections 4 and 4 for forming screw holes and the recess 5 for forming the door grip formed to be thicker than the thin plate portion 10. As a result, the sink mark M may appear on the front side 3a, or the opening 5a of the recess 5 for forming the door grip may be deformed. However, after molding the back member 3 as a first mold, the front member 2 serving as a second mold is injection-molded thereon.
The deformation of the sink mark M and the opening 5a appearing on the surface of the back member 3 is covered and covered by the plastic of the front member 2, and the difference in wall thickness caused by the sink mark M and the deformation is extremely small. No sink marks appear on the surface side 2a of the surface member 2 and the surface member 2 is not deformed.

According to this method, two injection steps, a primary injection step and a secondary injection step, are required until the plastic molded article 1 is completed. , 22 are alternately used, while one of the back-side molding dies 22 is being subjected to injection molding in the second-injection step for the one after the first injection step, the other back-side molding mold 22 is Injection molding can be performed at the same time as the primary injection process, and each process time can be shortened by a smaller amount of resin injection for one injection compared to normal injection molding. Even if the number increases, there is an advantage that the cycle time during which the plastic molded article 1 is continuously molded can be shortened, and the number of molded articles per unit time can be increased.

Finally, a transfer film on which a grain pattern is printed is attached to the front surface 2a of the plastic molded product 1 by a hydraulic transfer method, and the ink 11 is transferred to perform decoration. In this case, since the surface member 2 of the plastic molded article 1 is molded of brown plastic, when applying a wood grain pattern by the hydraulic transfer method, there is no need to apply the brown paint again, and the number of steps is reduced. can do.

In the above description, the case where the back member 3 is the first mold and the surface member 2 is the second mold has been described. However, the present invention is applicable to the case where either the first mold or the second mold is used. Good. For example, if the front surface member 2 is molded first and cured as a first mold, and the rear surface member 3 is molded later as a second mold, the front surface 2a of the front surface member 2 is already cured. Member 3
Even if sink or deformation occurs due to the difference in wall thickness, the surface member 2 does not sink or deform due to the influence.

Further, in the above description, a case has been described in which the front surface member 2 to be decorated is formed of a pre-colored plastic, and the back surface member 3 is formed of recycled plastic or the like. When it is intended to color the inner surface of the base member into an arbitrary color, the back surface member 3 can be formed of plastic colored in that color.
In this case, for example, in the case of coloring in black, the recycled plastic can be colored without decolorization (bleaching), so that the material cost is reduced, and in the case of coloring in other colors,
Since a step of applying a mask or the like by secondary processing and locally coating is not required, labor and labor can be reduced correspondingly.

[0025]

As described above, according to the present invention, a plastic molded product is provided with a surface member for decorating a surface side,
Form a two-layer structure of the back member having a protrusion on the back side, for example, after molding the back member as a first mold,
Since the two members are integrated by two injection moldings in which the front surface member is molded as a second mold, a difference in the thickness of the back surface member causes a difference in volume shrinkage, and a sink mark appears or deforms on the front surface side. However, since the difference in wall thickness is extremely small, when a surface member is injection-molded on top of it, there is an extremely excellent effect that sink marks do not appear on the surface side and no deformation occurs. In addition, if the base color resin used for decorating is used as the resin on the front side, no base color painting work is required after injection molding, and no intermediate painting process is required, and the total number of processes is reduced. Since it is reduced, there is an effect that not only the working efficiency is improved but also the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a plastic molded product according to the present invention.

FIG. 2 is a sectional view thereof.

FIGS. 3A to 3D are explanatory views showing a molding method according to the present invention.

FIG. 4 is a perspective view showing a conventional plastic molded product.

[Explanation of symbols]

1 ... plastic molding 2 ... surface member 2a · · surface 3 ... back member 3a · · surface side 3b · · backside 6 ... protruding portion P ₁ · · Primary injection position 25 ... primary injection device P ₂ · · second injection position 28 ... second injection device

Claims (3)

[Claims] 1. A plastic molded product in which a projection (6) such as a screw hole forming projection (4) is formed on a back side (3b) with respect to a front side (2a) to be decorated. A front member (2) having a decoration on the front side (2a) and a back member (3) having the protrusion (6) formed on the back side (3b); After molding either one of the member (2) and the back member (3) as a first mold, the other member of the front member (2) and the back member (3) to be a second mold is formed on the first mold. A plastic molded article wherein both the front member (2) and the back member (3) are integrated by two injection moldings. 2. The plastic molded article according to claim 1, wherein the plastic forming the surface member (2) is selected to have any color necessary for decorating the front side (2a). 3. A method of molding a plastic molded product in which a projection (6) such as a screw hole forming projection (4) is formed on the back side (3b) with respect to the front side (2a) to be decorated. The plastic molded article (1) is made up of a front member (2) that is decorated on the front side (2a) and a back member (2) on which the protrusion (6) is formed on the back side (3b). 3), a first injection step in which one of the front member (2) and the back member (3) is injection-molded as a first mold, and a first injection step formed in the first injection step. Secondary injection in which the other member of the front surface member (2) and the back surface member (3) is injection molded as a second mold so as to be integrated with the mold, and both the front surface member (2) and the back surface member (3) are integrated. And a molding method for a plastic molded product.