JP3604405B2 - Two-color container integral molding method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for integrally forming a two-color container, and more particularly, to a method for forming a two-color merging portion in a clear straight line without distortion or disturbance when molding left and right color-coded containers. The present invention relates to a method for integrally forming a color container.
[0002]
TECHNICAL BACKGROUND OF THE INVENTION
BACKGROUND ART In recent years, plastic containers have been widely used as containers for transporting products such as foods.
[0003]
In particular, in such a plastic container, a stacking / nesting type container which can be easily stacked (stacked) at the time of transportation and overlapped (nested) so as not to be bulky at the time of storage has been developed and used.
[0004]
By the way, in order to identify the direction of a container such as a stacking / nesting type container at the time of work such as transportation and storage, generally,
(1) A method of providing a window or the like in one direction of a container and using a photoelectric tube for identification;
(2) A method of attaching a reflective sticker to a part of the container and reading it,
(3) Mark the container with a stamp or attach a label, insert piece, etc. to identify it.
(4) A method such as a method of reading a color difference between two-color containers that are color-coded into left and right colors is used.
[0005]
Of these, the two-color container has many advantages, such as being able to visually identify the direction of the container and being able to simplify the structure and thus being easy to clean. Are better. Such a two-color container is disclosed, for example, in JP-A-60-19515.
[0006]
Two-color containers including this stacking nesting type container are usually injection-molded into a cavity in a mold from a thermoplastic polymer composition such as polypropylene, each colored in a desired color, from different directions, The two colored resins are merged at a substantially central portion of the cavity to be integrally formed. A plurality of openings may be formed on the side wall of such a two-color container in order to give the container air permeability.
[0007]
By the way, in a two-color container having an opening in a side wall obtained by a conventional integral molding method, a boundary (merging line) between colors may be distorted or disturbed, and a clear straight line may not be obtained.
[0008]
Such a two-color container in which the merging lines do not have a straight line shape is inferior in appearance, and in some cases, may be a defective product, thereby lowering the yield at the time of molding the two-color container.
[0009]
For this reason, there is a demand for an integrated molding method of a two-color container in which a boundary between colors, that is, a merging line is straightened without being distorted or disturbed.
The present inventor has studied in view of such a conventional technique, and as a result, the joining of the two differently colored resins injected into the cavity in the mold from different directions, the opening of the side wall is formed. The present invention is based on the finding that, when the operation is performed at the provided portion and the wall distance between the opening on the merging line and the opening adjacent in the left-right direction is 12 mm or more, the merging line is formed as a clear straight line. Was completed.
[0010]
[Object of the invention]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for integrally forming a two-color container in which a two-color merging line of a two-color container that is color-coded in the left-right direction can be formed in a clear straight line.
[0011]
Summary of the Invention
The method of integrally molding a two-color container according to the present invention comprises:
Consists square or a rectangular bottom plate portion, and the bottom plate portion a pair of side walls and a pair of end walls erected on the periphery of,
A plurality of openings are formed in the pair of side walls,
The bottom plate portion and the pair of side walls are merged lines formed so as to be located at a substantially central portion from the pair of end walls, and are color-coded in the left-right direction when viewed from the side wall side,
In the side wall, the merging line is located at a side wall portion located above and below an opening located at a substantially central portion from the pair of end walls of the side wall,
In the side wall, a wall distance between an opening located on the merging line and an opening adjacent in the left-right direction when viewed from the side wall of the opening is 12 mm or more;
A method of integrally molding a two-color container, wherein the pair of end walls are color-coded according to the color of the side wall,
A mold cavity corresponding to a side wall portion located above and below an opening located at a substantially central portion from a pair of end walls of the container at a substantially central portion in the left-right direction of the mold cavity corresponding to a side wall of the container. As a part is formed,
In the side wall of the container, a mold cavity portion is formed such that a wall distance between an opening located on the merging line and an opening adjacent in the left-right direction when viewed from the side wall of the opening is 12 mm or more. Using the formed mold,
Thermoplastic resins colored differently from each other are injected into the mold cavities from separate gates of the mold corresponding to the bottom plate portion that is color-coded in the left-right direction when viewed from the side wall side of the container ,
Said the injected dichroic resin, - is characterized in that is merged with the mold cavity portions corresponding to the side wall portion located above and below the opening located at substantially the center portion of a pair of end walls of the container .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a method for forming a two-color container according to the present invention will be described with reference to the drawings.
First, the shape of the two-color container formed by the present invention will be described.
[0013]
FIG. 1 is a schematic perspective view of a stacking / nesting type two-color container 1.
In the figure, the two-color container 1 includes a bottom plate 3, a pair of side walls 2 a and 2 b erected on the periphery of the bottom plate 3, and a pair of end walls 2 c and 2 d. A plurality of openings 4 are provided in the side walls 2a and 2b. A container having such an opening 4 has good air permeability. In the two-color container 1, the side walls 2a, 2b are color-coded left and right at substantially the center.
[0014]
The bottom plate 3 may have a grid-like rib (not shown) at its lower part.
In the present invention, the two-color container 1 is integrally molded by injecting a two-color thermoplastic resin using an injection mold having a cavity corresponding to such a container shape.
[0015]
FIG. 2 shows a vertical sectional view of the injection mold.
In the mold, a cavity 10 having a shape corresponding to the container 1 as described above is formed by a movable mold (male mold) 8 and a fixed mold (female mold) 9. A runner block 11 is fixed to one side of the fixed mold 9, and an end (sprue) of the runner block 11 is connected to the nozzles 13a and 13b of the injection devices 15a and 15b at the center of the runner block 2. Book passages 12a and 12b are formed. In the runner block, two runners 11a and 11b communicating with the passages 12a and 12b respectively extend in opposite directions so as to be substantially parallel to the cavity 10. Further, the runners 11a, 11b communicate with the cavity 10 by gates (passages) 16a, 16a, 16b, 16b provided at two locations, respectively.
[0016]
Resin colored in different colors, which have been melted separately, are advanced from the respective nozzles 13a, 13b of the heating cylinders 14a, 14b into the mold by advancing screws (not shown) in the injection devices 15a, 15b, respectively. It is injected into the passages 12a and 12b. The resin injected into the mold flows from the passages 12a, 12b into the runners 11a, 11b, and is pressed into the cavity 10 through the gates 16a, 16a, 16b, 16b.
[0017]
In the present invention, an example in which the injection molding die shown in FIG. 2 is used for integrally molding the two- color container 1 has been described, but the injection molding die used in the present invention is not limited to this example. For example, the number of gates communicating with the cavity may be such that at least one gate communicates with each injection device. Even when a plurality of gates are provided, the number is not limited. The position of such a gate is appropriately set depending on the shape of the container to be obtained. For example, in the case of obtaining a substantially symmetrical container, the gates of the resin of each color are connected to the merging line of the two colors. It is preferable that they are provided substantially line-symmetrically to the left and right. Further, the injection device may be of a screw type or a plunger type, and its operating mechanism is not limited.
[0018]
In the present invention, a molten thermoplastic resin colored in different colors is simultaneously injected into the injection mold as described above, and the resins are merged at a substantially horizontal center in the cavity 10 to merge. A line C is formed, and the container 1 which is color-coded left and right with different colors from the merging line C is integrally formed.
[0019]
When the container 1 is viewed from the side wall surface side, the merging line C may be formed on the left side or the right side of the substantially central portion of the container 1. The thermoplastic resins colored differently from each other usually consist of a thermoplastic resin and a pigment (dye).
[0020]
As the thermoplastic resin, a resin widely used in injection molding of plastic is generally used without any particular limitation. Examples include polypropylene (PP), polyethylene (PE), ABS resin, polystyrene (PS), polycarbonate (PC), polyvinyl acetate (EVA resin), polyamide (PA), and polyacetal (POM).
[0021]
The thermoplastic resins charged into the injection devices 15a and 15b are different in color, that is, different only in pigment (dye), and it is preferable to use the same resin.
As the pigment to be mixed with the resin, pigments or dyes generally used for coloring plastics are used without any particular limitation.
[0022]
Further, additives such as heat stabilizers and weather stabilizers, fillers such as glass fibers and fillers, etc. are appropriately blended with the thermoplastic resin according to the intended use of the obtained container.
[0023]
Injection molding of such a thermoplastic resin is generally performed under conditions such as melting temperature and pressure during injection molding of plastic, but in the present invention, a molten resin injected from different directions, It is carried out while adjusting the injection pressure and the like so that it merges at a desired position, usually at substantially the center of the cavity.
[0024]
According to the present invention, at the time of such injection molding, as shown in FIG. 2, separate gates 16a of the mold corresponding to the bottom plate portions which are color-coded in the left-right direction when viewed from the side walls 2a, 2b of the container 1. , 16b into the mold cavity 10. Then, as described above, the resins of different colors, which have flowed from different directions, respectively, are merged substantially at the center of the container.
That is, according to the present invention, as shown in FIGS. 1 and 3, in the side walls 2a and 2b having a plurality of openings 4, resins of different colors flowing opposite to each other are mixed with each other. At the portion where is provided .
At this time, as shown in FIG. 3, the molten resin flowing from the portion corresponding to the bottom plate portion of the mold to the side walls 2a and 2b in the mold cavity 10 is left and right of the central openings 4a and 4d. At the portions of the mold cavities corresponding to the wall portions located at the positions (points indicated by P1 and P2 in FIG. 3), as shown by arrows in FIG. . Then, it flows into the mold cavity corresponding to the side wall between the vertically adjacent openings 4a and 4d from the left-right direction, and substantially the center of the mold cavity corresponding to the side wall between the openings 4a and 4d. Will join.
In this case, the wall distances P1 and P2 between the opening 4a on the merging line C and the openings 4b and 4c adjacent to the opening 4a in the left-right direction are 12 mm or more, preferably 15 mm or more. Preferably, the distances P1 and P2 are equal.
[0025]
FIG. 3 is a diagram schematically showing the flow of the resin in the vicinity of the junction of the side walls.
In FIG. 3, different colors are indicated by a dot pattern and a hatched pattern.
As described above, in the present invention, the joining of the resin on the side walls 2a and 2b is performed at the portion where the opening 4 is provided on the side walls 2a and 2b, and the opening 4a on the joining line C and the opening 4a are respectively formed. the wall distance P ₁ or P ₂ between the opening 4b or 4c adjacent in the horizontal direction, since the 12mm or more, stable in the resin each other confluence of different colors flowing opposite to each other, and therefore There is no disturbance or distortion in the flow of the resin at the merging line C, and the merging line C is formed in a straight line.
[0026]
On the other hand, when resin of different colors flowing opposite to each other is performed at the point where the opening is provided, the space between the opening 4a and the opening 4b or 4c adjacent to each other in the left-right direction is determined. If the wall distance (P ₁ or P ₂ ) is less than 12 mm, the resin will be disturbed in the direction of the resin in the vicinity of the merging line, making it impossible to form the merging line in a straight line.
[0027]
In the present invention, the left-right direction of the length P ₃ of the opening portion 4a of the confluence line is not particularly limited, the distance P ₄ is 6mm between the opening 4d of vertically adjacent the opening 4a of the confluence line the case or less, and preferably _{P 3} is 20mm or more.
[0028]
By doing so, the merging line can be made more straight.
The two-color container obtained by the present invention as described above is preferably used particularly as a stacking / nesting type container, but need not always be used as a stacking / nesting type container.
[0029]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the integral molding method of the two-color container which concerns on this invention, the merging line of right and left two colors different from each other can be obtained by a straight line without distortion or disturbance.
[Brief description of the drawings]
FIG. 1 shows a perspective view of a stacking nesting type two-color container obtained by the present invention.
FIG. 2 is a horizontal sectional view of the injection mold used in the present invention as viewed from a side wall of the two-color container of FIG. 1 ;
FIG. 3 is a schematic diagram showing a flow of resin in the vicinity of a resin merging line in the present invention.

Claims (1)

Consists square or a rectangular bottom plate portion, and the bottom plate portion a pair of side walls and a pair of end walls erected on the periphery of,
A plurality of openings are formed in the pair of side walls,
The bottom plate portion and the pair of side walls are merged lines formed so as to be located at a substantially central portion from the pair of end walls, and are color-coded in the left-right direction when viewed from the side wall side,
In the side wall, the merging line is located at a side wall portion located above and below an opening located at a substantially central portion from the pair of end walls of the side wall,
In the side wall, a wall distance between an opening located on the merging line and an opening adjacent in the left-right direction when viewed from the side wall of the opening is 12 mm or more;
A method of integrally molding a two-color container, wherein the pair of end walls are color-coded according to the color of the side wall,
A mold cavity corresponding to a side wall portion located above and below an opening located at a substantially central portion from a pair of end walls of the container at a substantially central portion in the left-right direction of the mold cavity corresponding to a side wall of the container. As a part is formed,
In the side wall of the container, a mold cavity portion is formed such that a wall distance between an opening located on the merging line and an opening adjacent in the left-right direction when viewed from the side wall of the opening is 12 mm or more. Using the formed mold,
Thermoplastic resins colored differently from each other are injected into the mold cavities from separate gates of the mold corresponding to the bottom plate portion that is color-coded in the left-right direction when viewed from the side wall side of the container ,
The injected two-color resin is joined from a pair of end walls of the container at a mold cavity portion corresponding to a side wall portion located above and below an opening located at a substantially central portion. An integral molding method for two-color containers.

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