JP6957841B2 - Manufacturing method of synthetic resin container - Google Patents

Description

The present invention relates to a method of manufacturing a container made of stackable plastic.

Conventionally, a container made of synthetic resin, which is formed by forming a bottomed tubular preform using a thermoplastic resin such as polyethylene terephthalate and then molding this preform into a bottle shape by biaxial stretching blow molding or the like. It is generally used in a wide range of fields as a container containing various beverages and various seasonings.

Then, with respect to this type of synthetic resin container, a recessed recess in which the mouth side of another container can be inserted is provided at the bottom of the container so that two or more containers can be stacked up and down, which is stackable. Containers are known (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-125236

However, in such a stackable container, the recessed recess provided at the bottom of the container has a shape that is largely recessed inward to the extent that the mouth side of the inserted container can be covered. There is. Therefore, at the time of blow molding, for example, as shown in FIG. 10, the bottom mold BMp1 for molding the recessed recess is hindered from stretching the preform PF, and a portion for molding the ground contact portion at the bottom of the container in the mold. There is a problem that the preform PF is not stretched to CG and the ground contact portion cannot be formed. Such a problem is particularly remarkable in a container in which the recessed recess occupies a large proportion of the total area of the bottom and the area of the ground contact portion is small.

Further, in order to solve such a problem, for example, as shown in FIG. 11, it is conceivable to make the bottom mold BMp2 for forming the recessed recess movable. That is, the preform PF is extended until it reaches the bottom BMp2 located at the bottom dead center beyond the portion CG that forms the ground contact portion at the bottom of the mold, and then the bottom BMp2 is raised to the top dead center. Therefore, it is conceivable to shape the bottom shape provided with the recessed recess by inversion while pushing back the portion extended beyond the portion CG.

However, in this case, the portion extended beyond the portion CG for forming the ground contact portion at the bottom of the mold is set to have a sufficient length as an inversion allowance for inverting this and forming the recessed recess. , depending on the depth of the depression recess, it is necessary to increase the stroke S ₀ of the bottom type BMP2, for that purpose, leads to enlargement of the apparatus, its formation is not capable of easily.

Therefore, as shown in FIG. 12, the present inventors increase the diameter of the bottom mold insertion portion to form a space in which the stretched preform can enter between the inner peripheral surface thereof and the bottom mold MBp3. Therefore, it was considered that a sufficient length of inversion allowance could be secured for the stretched preform without lengthening the stroke S1 of the bottom type BMp3, and an attempt was made.
However, in this case, since the tip end side of the stretched preform is in a free state, if the preform has even a slight uneven thickness, there is a possibility that excess or deficiency may occur due to the influence. Then, if the stretching is insufficient, the inversion allowance cannot be secured and the shaping becomes poor, and if the stretching is excessive, there is a problem that burrs are generated due to the excess meat when the inversion occurs.

The present invention has been made in view of the above circumstances, and a recessed recess into which the mouth side of another container can be inserted is provided at the bottom of the container so that two or more containers can be stacked one above the other. in the synthetic resin container, and an object thereof is to provide a method for manufacturing a bottom shaped recessed recess is provided shaping property may well shaped stackable plastic containers.

The method for manufacturing a synthetic resin container according to the present invention is as follows.

That is, it is provided with a mouth, a shoulder, a body, and a bottom, and a recessed recess into which the mouth side of another container can be inserted is provided in the bottom so that two or more containers can be stacked one above the other. This is a method for manufacturing a synthetic resin container, which is attached to the mouth of the other container by reducing the diameter concentrically with respect to the base portion rising along the inner peripheral edge of the ground contact portion at the bottom. A bottom mold having a lid fitting portion into which the lid is loosely fitted and having a shape corresponding to the recessed recess in which the base portion and the lid fitting portion are connected via a step portion is provided. wherein the vertically movable through the bottom mold insertion portion drilled along the inner periphery of a portion forming the ground part Rutotomoni in the mold, when the bottom mold is positioned at the bottom dead center, the bottom mold On the vertical surface including the axis of the bottom mold, the inner peripheral surface of the bottom mold insertion portion, the horizontal plane including the edge portion of the step portion molding portion for molding the step portion, and the lid fitting portion for molding the lid fitting portion. Using a blow molding mold formed so that the radius of curvature R of the three-point inscribed circle in contact with the side surface of the molded portion is 5 mm or more, the preform is heated and softened so that blow molding is possible. Blow molding is started in a state where the bottom mold is set in the blow molding mold and the bottom mold is kept waiting at the bottom dead point, and the bottom mold located at the bottom dead point is reached beyond the portion where the ground contact portion is molded. by stretching the preform to reach the inner peripheral surface of the bottom mold insertion portion, and the lid fitting portion forming section, surrounded by the space between the stepped portion forming part, stretched the preform The tip side of the molding intermediate is formed, and then the bottom mold is raised to invert the molded intermediate while pushing back the portion of the molding intermediate that is extended beyond the portion where the ground contact portion is molded. , It is characterized by completing blow molding.

According to the method for manufacturing a synthetic resin container according to the present invention, it is possible to secure a sufficient length of inversion allowance without lengthening the stroke of the bottom mold, and further, the tip side of the stretched preform is because it is regulated by the stepped portion forming part of the bottom mold, Ru can der to ensure that excess or deficiency in the stretching of the portion to be a reversal allowance does not occur.

As a result , the shape of the bottom portion of the synthetic resin container provided with the recessed recesses can be well formed with good shapeability.

It is a front view which shows the outline of one Embodiment of the synthetic resin container which concerns on this invention. It is explanatory drawing which shows an example of the manufacturing method of the synthetic resin container which concerns on this invention. It is an enlarged view of the main part of FIG. It is explanatory drawing which shows an example of the manufacturing method of the synthetic resin container which concerns on this invention. It is explanatory drawing which shows an example of the manufacturing method of the synthetic resin container which concerns on this invention. It is explanatory drawing which shows an example of the bottom mold of the blow molding mold used in embodiment of this invention from the perspective. It is explanatory drawing which shows the other example of the bottom mold of the blow molding type used for embodiment of this invention perspectively. It is explanatory drawing which shows the other example of the bottom mold of the blow molding type used for embodiment of this invention perspectively. It is a front view which shows the outline of the modification of one Embodiment of the synthetic resin container which concerns on this invention. It is explanatory drawing which shows an example of the prior art. It is explanatory drawing which shows the other example of the prior art. It is explanatory drawing which shows the examination example of the manufacturing method of the synthetic resin container.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The container 1 according to the present invention includes a mouth portion 2, a shoulder portion 3, a body portion 4, and a bottom portion 5. In the container 1 illustrated as an embodiment of the present invention, the body portion 4 is formed in a cylindrical shape. In addition, it has a container shape generally called a round bottle.

In such a container 1, a bottomed tubular preform is formed by injection molding, compression molding, or the like using a thermoplastic resin, and this preform is formed into a predetermined container shape by biaxial stretching blow molding or the like. Manufactured by

As the thermoplastic resin used in manufacturing the container 1, any resin capable of blow molding can be used. Specifically, thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, acrylate polyarylate, polylactic acid or copolymers thereof, and those blended with these resins or other resins are preferable. Is. In particular, ethylene terephthalate-based thermoplastic polyesters such as polyethylene terephthalate are preferably used. Further, polycarbonate, acrylonitrile resin, polypropylene, propylene-ethylene copolymer, polyethylene and the like can also be used.

The mouth portion 2 is a cylindrical portion serving as an outlet for taking out the contents, and a lid 6 for sealing the inside of the container is attached to the mouth portion 2.
In addition, in FIG. 1, a part of the lid body 6 is cut out and shown.

Further, the lower end of the mouth portion 2 is connected to the shoulder portion 3 that expands in diameter toward the body portion 4 and connects the mouth portion 2 and the body portion 4, and in the illustrated example, the shoulder portion 3 is a cone. It is formed in a trapezoidal shape.

The body portion 4 occupies most of the height direction of the container 1, and the upper end is connected to the shoulder portion 3 and the lower end is connected to the bottom portion 5. Although not shown in particular, the body 4 is provided with a decompression absorption panel that absorbs the pressure decrease in the container cooled to room temperature after filling and sealing the contents with a so-called hot pack, and a load-bearing strength in the lateral direction. An annular lateral groove or the like for raising can be provided as needed.

Here, the height direction means a direction orthogonal to the horizontal plane when the container 1 is upright on the horizontal plane with the mouth portion 2 facing up, and in this state, the vertical and horizontal directions and the vertical and horizontal directions of the container 1 Shall be specified. Further, the same applies to the blow molding mold 100 for molding the container 1, and the direction thereof shall be defined corresponding to the container 1 to be molded.

Further, the bottom portion 5 has a grounding portion 50 for contacting the horizontal plane and enabling the container 1 to stand on its own when the container 1 is erected on a horizontal plane, and the side surface of the bottom portion 5 is grounded. It is connected to the lower end of the body portion 4 while being curved diagonally upward along the outer peripheral edge of the portion 50. In the illustrated example, the ground contact portion 50 is formed so as to extend in an annular shape along the circumferential direction, but the specific shape thereof is not limited as long as the container 1 can stand on its own.

Further, the bottom portion 5 is provided with a recessed recess 51 in which the central portion thereof is recessed inward of the container so that the mouth portion 2 side of the other container 1 can be inserted. By providing such a recessed recess 51, as shown in FIG. 1, the container 1 is capable of stacking two or more containers 1 one above the other.

The recessed recess 51 has a base portion 52 that rises along the inner peripheral edge of the ground contact portion 50 and a lid body 6 that is concentrically reduced in diameter with respect to the base portion 52 and is attached to the mouth portion 2 of the other container 1 to play. It has a lid fitting portion 53 that fits in a fitting shape, and the base portion 52 and the lid fitting portion 53 are connected to each other via a step portion 54.

In the present embodiment, the lid fitting portion 53 is formed coaxially with the axis of the container 1 so that two or more containers 1 can be stacked coaxially, and is stacked upward on the shoulder portion 3. It is preferable to provide an annular engaging portion 30 that engages with the peripheral edge of the opening of the recessed recess 51 of the container 1. By doing so, the containers 1 can be stacked in a more stable state.

In such a container 1, the bottom mold BM for forming the recessed recess 51 is movable so that the shape of the bottom portion 5 provided with the recessed recess 51 that is largely recessed in the container is formed with good shapeability. It can be manufactured using the blow molding die 100 (see FIG. 2).

The blow molding die 100 has a configuration in which the bottom die BM is inserted into a bottom die insertion portion formed in the vertical direction along the inner peripheral edge of the portion CG for forming the ground contact portion 50 of the bottom portion 5 in the mold. ing. The bottom type BM has a sliding portion BM0 that slides on the inner peripheral surface 101 of the bottom type insertion portion, and can be moved up and down in the bottom mold insertion portion in the vertical direction by a driving device (not shown). ..
Further, the bottom mold BM has a shape corresponding to the recessed recess 51, and together with the sliding portion BM0, a lid fitting portion molding portion BM53 for molding the lid fitting portion 53 and a step portion molding for molding the step portion 54. It has a portion BM 54 and a base molding portion BM 52 for molding the base 52.

In order to manufacture the container 1, first, as shown in FIG. 2, a preform PF that has been heated and softened so that it can be blow-molded is set, and the bottom mold BM is made to stand by at the bottom dead center. In this state, the blow molding die 100 is closed. Then, while moving the drawing rod (not shown) downward, blow air is blown into the preform PF to start blow molding.

At this time, the preform PF can be uniformly stretched by appropriately adjusting the downward speed of the stretching rod, the pressure of the blow air, etc. Then, the preform PF is stretched until it reaches the bottom mold BM located at the bottom dead center to obtain a molding intermediate MM (see FIG. 4). Next, the bottom mold BM is raised to the top dead center, and the blow molding is completed while pushing back and reversing the portion stretched beyond the portion CG. As a result, the stretched preform PF is brought into close contact with the molding surface of the blow molding die 100 to shape the shape (see FIG. 5).

In manufacturing the container 1 in this way, in the present embodiment, the tip end side of the preform PF stretched by blow molding is the inner peripheral surface 101 of the bottom mold insertion portion and the lid fitting of the bottom mold BM. A portion that enters the space surrounded by the part forming portion BM53 and the step forming portion BM54 of the bottom mold BM (see FIG. 4) and extends beyond the portion CG that forms the ground contact portion 50 of the bottom portion 5 in the mold. However, this can be inverted to have a sufficient length as an inversion allowance for forming the recessed recess 51. Therefore, it is possible to secure a sufficient length of reversal allowance without lengthening the stroke S of the bottom type BM. Further, according to the present embodiment, the tip end side of the stretched preform is regulated by the stepped portion BM54 of the bottom mold BM, so that there is no excess or deficiency in stretching the portion to be the inversion allowance. It is also possible to form the shape of the bottom portion 5 provided with the recessed recess 51 with good shapeability.

Further, in order to enable the shape of the bottom portion 5 provided with the recessed recess 51 to be formed better with good shapeability, the step portion forming portion BM54 is formed when the bottom mold BM is located at the bottom dead center. It is preferable that the distance along the height direction from the portion CG for forming the ground contact portion 50 of the bottom portion 5 in the mold to the step portion forming portion BM54 is at a position equivalent to the height H of the base forming portion BM52. That is, the stroke S of the bottom mold BM is preferably twice the height H of the base molding portion BM52. Further, the height h from the lower end of the base molding portion BM52 to the upper end of the lid fitting portion molding portion BM53 is preferably 20 mm or more.
The side surface of the lid fitting portion molded portion BM53 and the side surface of the base molded portion BM52 are preferably tapered surfaces in consideration of the draft. Further, it is preferable to add R to the lid fitting portion molding portion BM53 side of the step portion molding portion BM54 in consideration of shapeability.

Further, the lid fitting portion molded portion BM53 has a horizontal surface including an inner peripheral surface 101 of the bottom mold insertion portion and an edge portion of the step portion molded portion BM54 of the bottom mold BM in a vertical plane including the axis of the bottom mold BM. It is preferable to form the three-point inscribed circle iC in contact with the side surface of the lid fitting portion molded portion BM53 of the bottom mold BM so that the radius of curvature is 5 mm or more (see FIG. 3).
Note that FIG. 3 is an enlarged view of a main part in FIG. 2 in which the portion surrounded by the alternate long and short dash line is enlarged.

By doing so, it is possible to prevent the tip shape of the stretched preform PF that has reached the step forming portion BM54 from becoming uneven along the circumferential direction. As a result, stable molding with high reproducibility of the molding intermediate MM becomes possible, and the shapeability in blow molding can be improved.

As a result, the container 1 finally manufactured through blow molding has a vertical line passing through the inner peripheral edge of the ground contact portion 50, a horizontal plane including the edge portion of the step portion 54, and a lid in the vertical plane including the axis thereof. The radius of curvature of the three-point inscribed circle in contact with the side surface of the body fitting portion 53 is formed to be 5 mm or more, and the shape of the bottom portion 5 is well formed with good shapeability.

Further, when the bottom mold BM is raised and the portion stretched beyond the portion CG for forming the ground contact portion 50 at the bottom of the mold is pushed back and inverted, the portion is caught in the inside of the container and is rolled into the bottom mold. It is shaped into a BM and formed into a recess 51. Therefore, the lengths (peripheral lengths) along the circumferential direction do not match, and wrinkles may occur in the formed recessed recess 51 due to the difference in peripheral length between before and after inversion.

It is preferable that the bottom type BM is provided with an uneven shape for absorbing such a difference in circumference to suppress the occurrence of wrinkles or to make the wrinkles inconspicuous even if they occur.
For example, as shown in FIG. 6, a plurality of convex ridges BM55 straddling the side surface of the lid fitting portion molding portion BM53 and the step portion molding portion BM54 are formed along the circumferential direction to provide the uneven shape. You may. In the container 1 formed by using the bottom mold BM provided with such an uneven shape, a plurality of concave grooves straddling the side surface of the lid fitting portion 53 and the step portion 54 are formed in the recessed recess 51 along the circumferential direction. It is formed and the occurrence of remarkable wrinkles is suppressed.

Further, as shown in FIG. 7, the uneven shape provided on the bottom mold BM may be provided by forming a plurality of concave grooves BM56 on the side surface of the base forming portion BM52 along the circumferential direction. In the container 1 formed by using the bottom mold BM provided with such an uneven shape, a plurality of ridges are formed along the circumferential direction on the side surface of the base portion 52 of the recessed recess 51, and the occurrence of remarkable wrinkles is suppressed. It will be the one that was done.

Further, as shown in FIG. 8, the occurrence of remarkable wrinkles can be suppressed by partially cutting out the base molding portion BM52 to provide an uneven shape. In this case, the base molding portion BM52 is partially cut out. It is preferable that the notched portion BM57 has a surface that is flush with the side surface of the lid fitting portion molded portion BM53. By doing so, a rib portion 57 extending flush with the lid fitting portion 53 is formed in the recessed recess 51 of the molded container 1 (see FIG. 9). As a result, the mouth portion side of the other container 1 inserted into the recessed recess 51 is supported by the rib portion 57, and the containers 1 can be stacked in a more stable state. In such an embodiment, it is preferable to form three or more rib portions 57 at equal intervals along the circumferential direction.

Although the present invention has been described above with reference to preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. Nor.

For example, in the above-described embodiment, the container 1 having a container shape called a round bottle is illustrated and described, but the illustrated example merely shows one embodiment of the present invention. The shape of the container to which the present invention is applied is not limited to that shown. The present invention has a technical feature in the shape of the recessed recess 51 provided in the bottom 5 so that two or more containers 1 can be stacked one above the other. It can be changed as needed.

That is, in the present invention, the recessed recess 51 provided in the bottom portion 5 is concentrically reduced in diameter with respect to the base portion 52 rising along the inner peripheral edge of the ground contact portion 50 of the bottom portion 5 and another container. If the lid body 6 attached to the mouth portion 2 of 1 has a lid fitting portion 53 that fits loosely, and the base portion 52 and the lid fitting portion 53 are connected to each other via the step portion 54. The configuration of details other than this can be appropriately changed without being limited to the above-described embodiment. In addition, the detailed configurations described in the above-described embodiment can be appropriately selected and combined.

The present invention can be widely used as a stackable synthetic resin container.

1 Container 2 Mouth 3 Shoulder 4 Body 5 Bottom 50 Grounding 51 Recessed recess 52 Base 53 Lid fitting 54 Steps 100 Blow molding 101 Inner peripheral surface of bottom insertion part BM Bottom type BM0 Sliding part BM52 Base molding part BM53 Lid fitting part Molding part BM54 Step part molding part

Claims (5)

Synthetic with a mouth, shoulders, body, and bottom, and a recess in the bottom that allows the mouth side of another container to be inserted so that two or more containers can be stacked one above the other. It is a method of manufacturing a resin container.
A lid that rises along the inner peripheral edge of the ground contact portion of the bottom and a lid that is concentrically reduced in diameter with respect to the base and that is attached to the mouth of the other container in a loose fit. The bottom mold having a fitting portion and having a shape corresponding to the recessed recess in which the base portion and the lid fitting portion are connected via a step portion is inside the portion of the mold for forming the ground contact portion. Rutotomoni is vertically movably inserted into a bottom mold insertion portion drilled along the periphery, the bottom type, when positioned at the bottom dead center, in a vertical plane including the bottom mold of the axis, said bottom mold A three-point inscribed circle in contact with the inner peripheral surface of the insertion portion, the horizontal plane including the edge portion of the step portion molding portion for molding the step portion, and the side surface of the lid fitting portion molding portion for molding the lid fitting portion. Using a blow molding mold formed so that the radius of curvature R of is 5 mm or more,
A preform that has been heated and softened so that it can be blow-molded is set in the blow-molding mold, and blow-molding is started with the bottom mold waiting at the bottom dead center.
Beyond the portion for molding the ground portion, until it reaches the bottom mold located at the bottom dead center by stretching the preform, the inner peripheral surface of the bottom mold insertion portion, the lid fitting portion forming and parts, surrounded by the space between the stepped portion forming portions, and allowed enter the distal end side of the stretched the preform molding intermediates,
Next, the synthesis is characterized in that the blow molding is completed while raising the bottom mold and reversing the molding intermediate while pushing back the portion of the molding intermediate that is stretched beyond the portion for molding the ground contact portion. A method for manufacturing a resin container. When the bottom mold is located at the bottom dead point, the step portion molding portion forms the base portion by a distance along the height direction from the portion for molding the ground contact portion to the step portion molding portion. The method for manufacturing a synthetic resin container according to claim 1, wherein the height is equal to the height of the base molded portion of the bottom mold. By forming a plurality of protrusions straddling the side surface of the lid fitting portion molding portion and the step portion molding portion along the circumferential direction in the bottom mold, the side surface of the lid fitting portion is formed in the recessed recess. The method for manufacturing a synthetic resin container according to claim 1 or 2 , wherein a plurality of concave grooves straddling the step portion and the step portion are formed along the circumferential direction. By forming a plurality of recesses along the circumferential direction on the side surface of the base molding portion of the bottom mold for molding the base portion, a plurality of protrusions are formed on the side surface of the base portion of the recessed recess. The method for manufacturing a synthetic resin container according to claim 1 or 2 , which is formed along the direction. By partially cutting out the base molding portion of the bottom mold for molding the base portion and providing an uneven shape so that the bottom mold has a surface flush with the side surface of the lid fitting portion molding portion. The method for manufacturing a synthetic resin container according to claim 1 or 2 , wherein a rib portion extending flush with the lid fitting portion is formed in the recessed recess.

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