JPH06843A - Integrally molding method for two-color container - Google Patents

Abstract

PURPOSE:To form a two color confluent line in a sharp straight line by a method wherein a shielding plate is provided on a resin confluent position corresponding to a bottom plate part of a two-color container in a mold cavity, and the shielding plate is removed after resins of two colors are charged on the right and left sides of the shielding plate. CONSTITUTION:A shielding plate 30 is provided on a position corresponding to a bottom plate part 3 in an injection mold cavity corresponding to the shape of a two-color container 1. Resins are injected to flow from the right and left sides of the cavity corresponding to the bottom plate part 3. The flow of the resins is halted on the right and left sides of the shielding plate 30. After the shielding plate 30 is removed, the resins of two colors separately flow to be confluent along the shielding plate 30, thereby forming a straight confluent line L. The shielding plate 30 is removed within a period in which the surface layer of the resin is set but the center part remains in a melting state. Therefore, the confluent line L of the bottom plate part 31 is not disturbed but formed straight.

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 particularly, when molding a container that is color-coded into two colors, the two-color merging portion is formed into a clear straight line without distortion or disorder. The present invention relates to a method for integrally molding a two-color container that can be formed.

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

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. In particular, the two-color container is particularly superior to other methods. Excellent work efficiency. Such a two-color container is disclosed, for example, in 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 of a mold from different directions. It is molded and integrally molded by joining the resins colored in two colors at approximately the center of the cavity.

By the way, in the conventional two-color container obtained by the integral molding method, the boundary (confluence line) between the colors may be distorted or disturbed at the bottom plate of the container, so that a straight line may not be obtained. It was

[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.

Therefore, it is 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 becomes a straight line. The present inventor, as a result of research in view of such a conventional technique, has arranged a shielding plate for blocking the flow of the resin at a resin merging position in the cavity corresponding to the bottom plate portion, and the two-color synthetic resin The present invention was completed by finding that the joining line is formed as a clear straight line when the shielding plate is removed after the two are joined on the left and right sides of the shielding plate.

[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 a two-color merging line of a two-color container color-coded into two colors into a clear straight line.

[0011]

SUMMARY OF THE INVENTION A method for integrally molding a two-color container according to the present invention is a two-color container which comprises a bottom plate portion and side walls erected on the peripheral portion of the bottom plate portion, and which is divided into two colors in the left-right direction. , Injecting thermoplastic resins colored in different colors from the respective separate gates of the mold, and at the substantially central portion in the left-right direction, when the resins colored in different colors are joined together to integrally mold, A shielding plate that blocks the flow of resin is placed at the resin merging position in the cavity corresponding to the bottom plate, and these two colors of synthetic resin are merged on the left and right sides of the shielding plate, and then the shielding plate is removed. Is characterized by.

According to the present invention as described above, it is possible to obtain the two-color container in which the two-color merging lines for dividing the colors in the left and right directions are formed in a clear straight line.

[0013]

DETAILED DESCRIPTION OF THE INVENTION A method for molding a two-color container according to the present invention will be specifically described below with reference to the accompanying 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.
FIG. 3 is a vertical sectional view of an injection molding die used in the present invention, and FIG. 3 is a schematic enlarged view of a portion corresponding to the bottom plate portion of the two-color container 1 in the cavity of the injection molding die shown in FIG. FIG. 4 is a sectional view taken along line [IV]-[IV] of the bottom plate portion of the two-color container 1 in FIG. 3.

In FIG. 1, a two-color container 1 includes a bottom plate portion 3 and a pair of side walls 2 provided upright on the peripheral portion of the bottom plate portion 3.
c, 2d and a pair of end walls 2a, 2b. The two-color container 1 is color-coded into two colors by the joining line L on the bottom plate portion 3 and the side walls 2c and 2d.

In the present invention, the two-color container 1 as described above is used.
Using an injection molding die having a cavity corresponding to the shape of the container as shown in FIG. 2, two-color thermoplastic resins as described later are injected and integrally molded.

In the injection molding die shown in FIG. 2, a cavity 10 having a shape corresponding to the container 1 as described above is formed by a movable die (male die) 8 and a fixed die (female die) 9. Has been formed. The runner block 11 is provided on one side of the fixed mold 9.
Is fixed to the center portion of the runner block 11 and two passages 12a, the ends of which are connected to the nozzles 13a and 13b of the injection devices 15a and 15b.
12b is drilled. In addition, in the runner block,
Two runners 11 a and 11 b, which communicate with the passages 12 a and 12 b, 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, 16a, 16b and 16b, which are provided at two branches.
Communicates with the cavity 10. Further, the bottom plate portion in the cavity 10 where the merged resin reaches (see FIG.
(Corresponding to the bottom plate portion 3) is provided with a shield plate (not shown) which is detachable. The shielding plate may be provided on the fixed mold side or the movable mold side, and the installation place is not particularly limited.

In the above description, when the two-color container 1 is integrally molded, the injection mold shown in FIG. 2 is used, but the injection mold used in the present invention is not limited to this example. Not something.

For example, the number of gates communicating with the cavities may be such that at least one gate communicates with each injection device, and the number 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. The injection device may be a screw type or a plunger type as described above.

In order to integrally mold the two-color container 1 using the above-mentioned injection molding apparatus, first, the two-color containers 1 are melted separately,
The heating cylinders 14a and 14b are operated by operating the screws (not shown) in the injection devices 15a and 15b, respectively, with resins, which will be described later, colored in mutually different colors.
From the respective nozzles 13a and 13b of the
It is injected into a and 12b. The resin injected into the mold flows into the runners 11a and 11b from the passages 12a and 12b, and is pressed into the cavity 10 through the gates 16a, 16a, 16b and 16b. The two-color resin press-fitted into the cavity gradually flows toward the position of the shielding plate 30 disposed substantially in the center of the bottom plate portion in the left-right direction in the cavity 10, but the bottom plate portion of the container 1 in the cavity is gradually removed. 3 When reaching a shield plate 30 provided in advance in a portion corresponding to substantially the center, the shield plate 30 blocks the progress and stops (stores). Next, as shown in FIG. 4, the shield plate 30 is removed in the direction of the arrow (or the shield plate is released by pulling out in the direction of the arrow). The shield plate 3 is formed so as to follow the cross-sectional shape of the shield plate 30.
0 from both directions toward the confluent (planned) line L1 in the direction of the arrow in FIG. 3, and the confluent line L of the bottom plate portion 3 of the container 1
Is formed. When the joining line L (L1) of the bottom plate portion 3 of the container 1 is formed in this manner, there is no turbulence or distortion in the resin flow at the joining line L (L1), and the joining line L (L1) is formed.
Are linearly formed along the cross-sectional shape of the shield plate 30.

The merging line L may be formed on the left side or the right side of the container 1 which is color-coded to the left and right when the container 1 is viewed from the rear surface direction of the bottom plate. Further, the shape of the confluence line L can be modified by appropriately selecting the cross-sectional shape of the shielding plate, and in addition to the above linear shape, it can be curved if necessary.

The relationship between the time when the shield plate 30 is removed and the time when the movable mold is moved to take out the two-color container 1 is as follows. That is, it is preferable that the shielding plate 30 be removed within a period in which the resin skin layer (surface layer) in contact with the mold is solidified and the resin core portion (center portion) is kept in a molten state. More specifically, it is preferable to adjust the removal timing of the shielding plate before and after the resin forming the bottom plate portion 3 of the two-color container is filled. Further, the two-color container obtained after the completion of injection molding is taken out by moving the movable mold after a proper cooling time.

The two-colored thermoplastic resins colored in different colors, which are used when integrally molding such a two-colored container, usually contain a thermoplastic resin and a pigment (dye). .

As the thermoplastic resin, a resin that is widely used in injection-molding 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) or composition ratio thereof, and it is preferable to use the same resin.

As the pigment to be blended with the resin, pigments or dyes generally used for coloring plastics are used without particular limitation. Furthermore, in the thermoplastic resin, depending on the intended use of the resulting container,
Additives such as heat resistance stabilizers and weather resistance stabilizers, glass fibers, fillers such as fillers, etc. are appropriately mixed.

Such a thermoplastic resin is generally injection-molded under conditions such as a melting temperature and a pressure when a plastic is injection-molded, but in the present invention, as described above, injection is performed from different directions. It is carried out while adjusting the injection pressure and the like so that the molten resin thus obtained merges at a desired position where the shielding plate is provided, usually at the approximate center of the cavity.

In the above description, the stacking / nesting type container has been described as an example, but the present invention is not limited to the above-mentioned example and can be applied to various two-color injection molded articles.

In the above-mentioned two-color container, for example, a rib may be provided on the bottom surface, and the shape thereof may be a line parallel to or oblique to any side, or two adjacent sides. The ribs parallel to each other may be provided so as to be orthogonal to each other. In addition, the side wall portions 2c and 2d, the bottom plate portion 3
Etc., a plurality of holes for draining water may be provided.

[0030]

According to the method for integrally molding a two-color container according to the present invention, the two-color confluence line of the two-color container, which is color-coded into left and right two colors different from each other, can be obtained in a straight line shape without distortion or disorder.

Therefore, according to the present invention, the two-color container can be integrally molded with an excellent yield.

[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 in the portion corresponding to approximately the center of the two-color container bottom plate in the cavity provided with the shielding plate in the present invention.

FIG. 4 is a sectional view taken along line [IV]-[IV] in FIG. 3, in which the arrow indicates the direction in which the shield plate is removed.

[Explanation of symbols]

 1 ... Two-color container, 2a, 2b ... End wall, 2c, 2d ... Side wall, 3 ... Bottom plate part, 30 ... Shielding plate, L, L1 ... Confluence line.

Claims (1)

[Claims] 1. A two-color container, which comprises a bottom plate portion and side walls provided upright on the peripheral portion of the bottom plate portion and is color-coded into two colors in the left-right direction, is made of a thermoplastic resin colored in different colors from each other. When the resin is injected from different gates of the mold and the resins colored in different colors are merged at the central part in the left-right direction to integrally mold, the resin is placed at the resin confluence position in the cavity corresponding to the bottom plate. A method for integrally molding a two-color container, characterized in that a shielding plate for preventing the circulation of the two-color container is arranged in advance, the two-color synthetic resins are joined on the right and left sides of the shielding plate, and then the shielding plate is removed.