JPH05337985A - Method for integrally molding two-color container - Google Patents

Abstract

PURPOSE:To make a meeting line linear by allowing two color resins to meet with each other at a part not provided with a plurality of the opening parts formed to the side wall of a container and making the distance between opening parts adjacent to each other so as to hold the meeting line therebetween longer than that between opening parts adjacent to each other so as not to hold the meeting line therebetween. CONSTITUTION:A two-color container 1 is constituted of a bottom panel part 3 and the side walls 2a, 2b and end part walls 2c, 2d vertically provided to the peripheral edge parts of the bottom panel part 3. Many opening parts 4 are provided to the side walls 2a, 2b and the meeting line C of the container 1 divided into left and right different color parts along the meeting line C is provided to the parts provided with no opening parts 4 of the side walls 2a, 2b and the distance P2 between the opening parts 4a, 4b adjacent to each other so as to hold the meeting line C therebetween is made longer than the distance P1 between the opening parts 4d, 4e adjacent to each other so as not to hold the meeting line C therebetween. Therefore, a confluent point where different colors come to flow is stabilized and turblence or strain is eliminated in the flow of the resins at the part of the meeting line C and the meeting line C is formed linearly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for integrally molding a two-color container, and more specifically, when molding a container that is color-coded into left and right, a two-color merging portion is formed in a clear straight line shape without distortion or disturbance. And a method for integrally molding a two-color container.

[0002]

BACKGROUND OF THE INVENTION In recent years, plastic containers have been widely used as containers for transporting products such as foods.

In particular, in such a plastic container, a stacking / nesting type container has been developed and utilized, which is easily stacked (stacked) during transportation and is stacked (nested) so as not to be bulky during storage.

By the way, in order to identify the direction of the container such as the stacking / nesting type container at the time of the work such as transportation and accommodation, generally, (1) a window is provided in one direction of the container. , (2) How to identify by using photocell, (2) How to put a reflective sticker on a part of the container and read it, (3) Mark with a stamp on the container or attach a label, insert piece, etc. to identify Yes, (4) A method such as a method of reading the difference in color between two-color containers that are color-coded into two colors, right and left, is used.

Of these, the two-color container has many advantages in that the direction of the container can be visually identified, and the structure can be simplified so that it can be easily washed. Excellent work efficiency. Such a two-color container is disclosed in, for example, JP-A-60-19515.

Two-color containers, such as this stacking nesting type container, usually inject a thermoplastic polymer composition such as polypropylene colored in a desired color into a cavity in a mold from different directions. It is integrally molded by molding and joining resins colored in two colors at approximately the center of the cavity. In addition, a plurality of openings may be formed in the side wall of such a two-color container in order to provide air permeability to the container.

By the way, in the two-color container having an opening on the side wall obtained by the conventional integral molding method, the boundary (confluence line) between colors is distorted or disturbed, and a sharp straight line cannot be obtained. there were.

[0008] Such a two-color container in which the merging line is not linear is inferior in appearance, and in some cases, they may be defective products, which lowers the yield in molding the two-color container. ing.

For this reason, it has been desired to develop a method for integrally molding a two-color container in which the boundary between colors, that is, the confluence line is not distorted or disturbed and is straight. The present inventor, as a result of research in view of such a conventional technique, shows that the openings of the side walls allow the merging of resins colored in two different colors, which are respectively injected into the cavity in the mold from different directions. If the distance between adjacent openings is larger than the distance between adjacent openings without a junction line, the junction line will be clear. The inventors have found that they are formed by straight lines and have completed the present invention.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a two-color container integral molding method capable of forming the two-color merging lines of the two-color containers, which are color-coded in the left-right direction, into a clear straight line.

[0011]

SUMMARY OF THE INVENTION A method for integrally forming a two-color container according to the present invention comprises a bottom plate, a pair of side walls and a pair of end walls which are provided upright on the peripheral edge of the bottom plate, and a pair of side walls. The two-color containers are colored in the left and right directions, and thermoplastic resins colored in mutually different colors are injected into the cavities in the mold from the respective separate gates of the mold, and substantially the central portion in the left and right direction of the cavities. When the resins colored in different colors are merged and integrally molded, the resins of two colors are merged at a portion where the opening portion of the side wall is not provided, and they are adjacent to each other with a junction line interposed therebetween. The feature is that the distance between the openings is made longer than the distance between the adjacent openings without sandwiching the joining line.

[0012]

DETAILED DESCRIPTION OF THE INVENTION A method for molding a two-color container according to the present invention will be described below with reference to the drawings. First, the shape of the two-color container molded according to the present invention will be described.

FIG. 1 is a schematic perspective view of a stacking / nesting type two-color container 1. In the figure, a two-color container 1 includes a bottom plate portion 3, a pair of side walls 2a and 2b provided upright on a peripheral portion of the bottom plate portion 3 and a pair of end wall portions 2c and 2c.
It consists of 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. The two-color container 1 is color-coded on the left and right on the side walls 2a and 2b.

The bottom plate portion 3 may have a grid-like rib (not shown) at the bottom thereof. In the present invention, the two-color container 1 as described above is integrally molded by injecting two-color thermoplastic resins using an injection mold having a cavity corresponding to such a container shape.

FIG. 2 shows a vertical sectional view of the injection molding die.
Inside the mold, a movable mold (male mold) 8 and a fixed mold (female mold)
9 and 9 form a cavity 10 having a shape corresponding to the container 1 as described above. A runner block 11 is fixedly attached to one side of the fixed mold 9, and an end portion (a sprue) of the runner block 11 is coupled to the nozzles 13a and 13b of the injection devices 15a and 15b in the central portion of the runner block 2. Book passages 12a and 12b are provided. Further, in the runner block, two runners 11a and 11b, which communicate 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 and 11b are provided with gates (passages) 16a and 1 provided at two branches respectively.
It communicates with the cavity 10 by 6a, 16b and 16b.

The differently colored resins melted separately from the nozzles 13a, 13b of the heating cylinders 14a, 14b are moved by advancing screws (not shown) in the injection devices 15a, 15b. It is injected into the mold passages 12a and 12b. The resin injected into the mold is passed through the passages 12a and 12b to the runner 11a,
11b, and gates 16a, 16a, 16b, 1
It is pressed into the cavity 10 from 6b.

In the present invention, an example of using the injection mold shown in FIG. 3 when integrally molding the two-color container 1 has been described, but the injection mold used in the present invention is not limited to this example. is not. For example, the number of gates communicating with the cavity should be at least 1 for each injection device.
It suffices that each gate communicates with each other, and the number of gates is not limited even when a plurality of gates are provided. The position of such a gate is appropriately set depending on the shape of the obtained container. For example, when a substantially symmetrical container is to be obtained, the resin gates of the respective colors are connected to the joining line of the two colors. On the other hand, it is preferable that they are provided substantially symmetrically to the left and right. Further, the injection device may be a screw type or a plunger type, and its operating mechanism system is not limited.

In the present invention, the molten thermoplastic resins colored in mutually different colors are simultaneously injected into the injection molding die as described above, and the resins are joined together at the substantially horizontal center of the cavity 10. Then, the confluent line C is formed, and the container 1 colored in different colors with the confluent line C as a boundary is integrally molded.

The merging line C may be formed on the left side or the right side of the container 1 when the container 1 is viewed from the side wall surface side. Thermoplastic resins colored in different colors,
It usually consists of a thermoplastic resin and a pigment (dye).

As the thermoplastic resin, a resin which is widely used in injection molding of plastic is generally used without particular limitation. Examples thereof include polypropylene (PP), polyethylene (PE), ABS resin, polystyrene (PS), polycarbonate (PC), polyvinyl acetate (EVA resin), polyamide (PA), polyacetal (POM) and the like.

The thermoplastic resins charged in the injection devices 15a and 15b are different in color, that is, only different in pigment (dye), and the same resin is preferably used. As the pigment to be blended with the resin, pigments or dyes generally used for coloring plastics are used without particular limitation.

Furthermore, additives such as heat resistance stabilizers and weather resistance stabilizers, glass fibers, fillers such as fillers, etc. are appropriately blended with the thermoplastic resin depending on the intended use of the resulting container.

Injection molding of such a thermoplastic resin is generally carried out under conditions such as melting temperature and pressure at the time of injection molding of plastic, but in the present invention, the melting is performed in different directions. It is carried out while adjusting the injection pressure and the like so that the resins meet at a desired position, usually in the approximate center of the cavity.

In the present invention, upon such injection-integration molding, the resins of different colors that have flowed from different directions as described above are merged at approximately the center of the container.
In the present invention, as shown in FIG. 3, in the side walls 2a and 2b having a plurality of openings 4, portions of the side walls where the openings 4 are not provided for resin of different colors flowing in opposition to each other. And the distance P ₂ between the openings 4a and 4b adjacent to each other with the merging line C interposed therebetween is made longer than the distance P ₁ between the openings 4d and 4e adjacent to each other without the merging line C interposed. There is.

FIG. 3 is a diagram schematically showing the flow of resin in the vicinity of the merging portion of the side wall. In FIG. 3, different colors are indicated by a dot pattern and a diagonal pattern. As described above, in the present invention, the merging of the resin on the side walls 2a and 2b is performed at the portions where the side walls 2a and 2b are not provided with the openings 4, and the openings 4a and 4b adjacent to each other with the merging line C interposed therebetween.
The distance P ₂ is made longer than the distance P ₁ between the adjacent openings 4d and 4e without sandwiching the joining line C, whereby the resins of different colors flowing opposite to each other join each other. It is stable at the point, and therefore there is no turbulence or distortion in the resin flow at the joining line C, and the joining line C is formed in a straight line.

On the other hand, resins of different colors flowing in opposite directions are formed at the points where the openings are provided, or the distance P ₂ between the openings adjacent to each other with the joining line C interposed therebetween is set to If the distance is shorter than the distance P ₁ between adjacent openings without sandwiching the confluence line C, the resin is disturbed in the advancing direction of the resin in the vicinity of the confluence line, and the confluence line cannot be formed in a straight line.

The two-color container obtained by the present invention as described above is preferably used especially as a stacking / nesting type container, but it is not always necessary to use it as a stacking / nesting type container.

[0028]

According to the method for integrally molding a two-color container according to the present invention, a two-color container in which the confluence lines of the left and right two colors different from each other are linear can be obtained.

[Brief description of drawings]

FIG. 1 shows a perspective view of a stacking nesting type two color container obtained by the present invention.

FIG. 2 is a vertical cross-sectional view of an injection molding die used in the present invention.

FIG. 3 is a schematic diagram showing the flow of resin in the vicinity of the resin joining line on the side wall in the present invention.

[Explanation of symbols]

 1 ... Two color container, 2a, 2b ... Side wall, 2c, 2d ... End wall, 3 ... Bottom plate part, 4 ... Opening part, C ... Confluence line.

Claims (1)

[Claims] 1. A bottom plate, a pair of side walls and a pair of end walls that are provided upright on the peripheral edge of the bottom plate, and the pair of side walls are color-coded in the left-right direction and have a plurality of openings. The two-color container that has the thermoplastic resin colored in mutually different colors is injected into the cavity in the mold from the respective separate gates of the mold,
At the center of the cavity in the left-right direction, when the resins colored in different colors are merged and integrally molded, the two-color resins are merged at a portion where the opening portion of the side wall is not provided, A method for integrally molding a two-color container, characterized in that the distance between the openings adjacent to each other with the merging line in between is made longer than the distance between the openings adjacent without sandwiching the merging line.