JP7175751B2 - blow molded container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a blow-molded container having a cylindrical mouth, a body connected to the mouth, and a bottom closing the lower end of the body, and particularly to a blow-molded container having a polygonal bottom. Regarding.

2. Description of the Related Art Conventionally, synthetic resin blow-molded containers have been used as containers for containing various contents such as beverages, seasonings, cosmetics, medicines, detergents, and shampoos.

Such a blow-molded container can be molded, for example, by blow molding such as extrusion blow molding. In extrusion blow molding, for example, a cylindrical parison is extruded by an extruder, and the parison is clamped and sandwiched between two split molds that are divided vertically in the clamping direction, and the bottom of the cavity of the split mold is formed. The pinch-off part, which is a blade part arranged in the upper part, cuts the lower part of the molten resin and heat-welds and seals it. Then, blow molding is known in which blow air (pressurized gas) is blown into the parison by an air nozzle from the top of the split mold (see Patent Document 1).

JP 2009-241947 A

Here, FIGS. 5 and 6 show the process in which the parison resin 50 is expanded in the mold 60 by the pressurized gas blown into the cylindrical parison, and the container is molded. 5 and 6 show the lower part of the container in longitudinal cross-section through the axis O of the container and perpendicular to the parting line.

As shown in FIG. 5, in the process in which the parison resin 50 is gradually expanded by the pressurized fluid, the portion 51 corresponding to the body of the container contacts the inner surface 61 of the mold 60 first from the center in the height direction. Then, the portion 52 corresponding to the bottom gradually comes into contact with the inner surface 62 of the mold 60 from a region near the axis O. As shown in FIG. Finally, the portion 53 corresponding to the rising portion connecting the body and bottom of the container comes into contact with the inner surface 63 of the mold.

Then, the portions 51 and 52 that have previously contacted the inner surfaces 61 and 62 of the mold 60 are cooled by the mold 60 and solidified, making it difficult to flow. There is a problem that the thickness of the portion 53 tends to be thin (see FIG. 6).

In particular, in the case of a container having a polygonal shape such as a square when viewed from the bottom, and having a pair of corners opposed to each other across the parting line of the bottom, The thickness of the rising portion of the corner tends to be thin, and there is a risk that the rigidity will be insufficient.

In order to solve the problem that the corners of the bottom of the container are thin as described above, for example, there is a method of making the bent shape of the rising portion a curved shape with a large curvature radius, but the rising portion is large and rounded. Due to the shape, the design is restricted, and the degree of design freedom is limited.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a blow-molded container capable of appropriately securing the rigidity of a polygonal bottom portion without increasing restrictions on the appearance design.

The present invention has been made to solve the above problems, and the blow-molded container of the present invention comprises a cylindrical mouth, a trunk connected to the mouth, and a bottom closing the lower end of the trunk. and a blow-molded container comprising:
The bottom has a polygonal shape in bottom view and has at least a pair of corners facing each other across a parting line of the bottom,
Of the pair of corners, the corner located farthest from the parting line has an arcuate outward curve extending from the lower end of the trunk to the ground contact surface forming portion of the bottom when viewed in longitudinal section. and an arc-shaped inner curved portion continuous to the inner side of the outer curved portion,
the radius of curvature of the inner curved portion is greater than the radius of curvature of the outer curved portion;
The radius of curvature of the inner curved portion is 15 mm or more and 35 mm or less.

In addition, in the blow-molded container of the present invention, it is preferable that the radius of curvature of the outer curved portion is 1 mm or more and 4 mm or less.

Further, in the blow-molded container of the present invention, it is preferable that a corner portion located farthest from the parting line in the bottom view has an acute angle.

Further, in the blow-molded container of the present invention, an arc-shaped curved portion is provided at a corner portion located farthest from the parting line in the bottom view, and the curvature of the curved portion It is preferable that the radius is 1 mm or more and 6 mm or less.

ADVANTAGE OF THE INVENTION According to this invention, the blow-molded container which can ensure the rigidity of a polygonal bottom part appropriately can be provided, without increasing restrictions on an external design.

BRIEF DESCRIPTION OF THE DRAWINGS It is a front view which shows the blow molded container which concerns on one Embodiment of this invention with a partial cross section. Figure 2 is a side view of the blow molded container of Figure 1; Figure 2 is a bottom view of the blow molded container of Figure 1; FIG. 2 is a partially enlarged view of the blow-molded container shown in FIG. 1; It is a figure which shows a mode that a container is blow-molded using a metal mold|die. It is a figure which shows a mode that blow molding progresses from the state of FIG.

A blow-molded container 1 according to an embodiment of the present invention will be described in detail below with reference to the drawings. In this specification, the scope of claims, and the abstract, "upper" means the side where the mouth portion 2 is located with respect to the bottom portion 4 (upper side in FIG. 1), and "lower" is the opposite. the side (the side where the bottom portion 4 is located with respect to the mouth portion 2).

As shown in the front view of FIG. 1 and the side view of FIG. and a bottom portion 4 closing the lower end of the body portion 3 . In FIG. 1, the lower portion of the container 1 is shown in cross section along line AA of FIG. 3, and in FIG. 2, the lower portion of container 1 is shown in cross section along line BB of FIG. there is FIG. 3 is a bottom view of FIG. 1, and FIG. 4 is a partially enlarged view of FIG. is shown.

The inside of the container 1 is a storage space S for contents. The type of contents may be, for example, beverages, seasonings, cosmetics, medicines, detergents, shampoos, etc., but is not particularly limited, and may be in any form of liquid, gas, or solid.

The container 1 is made of synthetic resin, and can be made of materials such as polyethylene (PE) and polypropylene (PP), but the material is not limited to this. The container 1 is formed, for example, by molding a cylindrical parison by extruding a synthetic resin forming the container 1 in a molten state, sandwiching the parison between metal molds and blow molding (extrusion blow molding). be able to. The container 1 may have a structure in which barrier layers having barrier properties against oxygen and water vapor are laminated, or a structure in which the barrier properties are enhanced by various coatings.

The mouth portion 2 is formed in a cylindrical shape, and has an opening 2a at its upper end through which contents can be discharged. An outer peripheral surface of the mouth portion 2 is formed with a male screw portion 2b for attaching a cap, a discharge tool, or the like to the container 1. As shown in FIG. Instead of the male threaded portion 2b, a convex or concave engaged portion is provided, and the concave or convex engaging portion provided on the cap or the like engages with the engaged portion, whereby the cap or the A discharge tool or the like may be held in the mouth portion 2 .

The body portion 3 continues to the lower end portion of the mouth portion 2 and extends downward (diameter-wise expands) outward in the radial direction. and a polygonal cylindrical trunk body portion 3b extending along the .

As shown in FIGS. 1 and 2, the shoulder portion 3a of this example is inclined at a substantially constant angle with respect to the axis O, and has a flat shape with a straight outline. Instead, it may have a dome shape that protrudes toward the outside of the container, or it may have an inverted dome shape that becomes concave toward the inside of the container.

The trunk main body portion 3b of this example is formed in a rectangular tubular shape having a square cross section perpendicular to the axis O, but is not limited to this and can be changed as appropriate. The barrel body portion 3b of this example corresponds to the shape of the bottom portion 4, and the outer shape of the bottom portion 4 is configured to substantially match the cross section of the barrel body portion 3b. The trunk body portion 3b has a linear shape (straight shape) over the entire height of the trunk body portion 3b.

The container 1 shown in FIG. 1 is a front view of the pair of parting lines PL formed on the trunk portion 3 as viewed from one side (corner portion 3c side). The trunk main body portion 3b of this example has a cross section perpendicular to the axis O that is neither square nor rectangular, but has an asymmetrical shape. The cross section of the trunk main body 3b of this example does not have a regular polygonal shape, but the concave cross section may have a regular polygonal shape. Also, in this example, the parting line PL is formed so as to pass through the two corners 3c and 3d of the trunk main body 3b. The trunk body portion 3b has an asymmetrical shape with respect to a plane passing through the parting line PL.

The barrel main body 3b extends linearly along the axis O, and is configured such that four side surfaces thereof are flat surfaces. Note that the trunk main body portion 3b may have a pressure reduction absorption panel for absorbing internal pressure reduction, unevenness for increasing rigidity, a bulging portion that bulges toward the outside of the container, or It may have a constricted portion that is concave toward the inside of the container, or a twisted portion about the axis O, or the like.

The bottom portion 4 continues to the lower end of the trunk portion 3 (the lower end of the trunk main portion 3b). As shown in FIG. 3, the bottom portion 4 is formed in a square shape having at least a pair of corner portions 4a and 4b facing each other across the parting line PL when the container 1 is viewed from the bottom. In the case of the container 1 molded by extrusion blow molding, a pinch-off portion is formed on the parting line PL of the bottom portion 4 by parting the split mold. Curved portions 5a, 5b, 5c and 5d are provided at four corner portions 4a, 4b, 4c and 4d of the bottom portion 4, respectively. Note that the bottom portion 4 is not limited to a quadrilateral as long as it has a polygonal shape having at least a pair of corners facing each other across the parting line PL. In this example, the parting line PL of the bottom portion 4 is positioned on a straight line passing through the corner portions 4c and 4d.

The bottom portion 4 has a ground contact surface forming portion 7 which is located at the lowest position in the bottom portion 4 and forms a flat contact surface as a whole, and a raised bottom portion which is concave toward the inside of the container radially inside the contact surface forming portion 7. 8 and . The ground surface forming portion 7 is provided near the outer peripheral edge of the bottom portion 4 . In this example, as shown in FIG. 3, the ground surface forming portion 7 is formed in a substantially rectangular shape extending along a contour line forming the outer peripheral edge of the bottom portion 4 in bottom view.

As shown in FIG. 3, the bottom portion 4 of this example has an asymmetrical shape with respect to a plane passing through the parting line PL, similarly to the trunk main portion 3b. Of the pair of corners 4a and 4b that face each other across the parting line PL, the corner 4a that is farthest from the parting line PL is positioned from the lower end of the body 3 in the vertical cross-sectional view shown in FIG. It has an arc-shaped outer curved portion 9 extending over the ground-contacting surface forming portion 7 of the bottom portion 4 and an arc-shaped inner curved portion 10 continuous to the inner side (axis O side) of the outer curved portion 9 . The inner curved portion 10 constitutes a portion of the raised bottom portion 8 . The curvature radius r1 of the inner curved portion 10 is larger than the curvature radius r2 of the outer curved portion 9, and the curvature radius r1 of the inner curved portion 10 is 15 mm or more and 35 mm or less. Note that the center of curvature of the inner curved portion 10 is located above the bottom portion 4 . In other words, the inner curved portion 10 is curved so as to bulge out toward the outside of the container.

As shown in FIGS. 3 and 4, a flat central bottom wall portion 11 is provided radially inward of the inner curved portion 10 . Further, the outer curved portion 9 constitutes a rising portion where the bottom portion 4 and the trunk portion 3 are connected.

The curvature radius r2 of the outer curved portion 9 is preferably 1 mm or more and 4 mm or less. By setting the thickness to 4 mm or less, the shape of the rising portion can be sharply designed, and by setting the thickness to 1 mm or more, the thickness of the rising portion can be appropriately secured more reliably. More preferably, the radius of curvature r2 is 1.5 mm or more and 3.5 mm or less. Also, if the radius of curvature r2 is less than 1 mm, molding may become difficult.

In the container 1 of the present embodiment, the corner 4a at the farthest position from the parting line PL of the bottom 4 extends from the lower end of the body 3 to the ground contact surface forming portion 7 of the bottom 4 in a vertical cross-sectional view. It has an extending arc-shaped outer curved portion 9 and an arc-shaped inner curved portion 10 connected to the inner side (axis O side) of the outer curved portion 9, and the curvature radius r1 of the inner curved portion 10 is the outer curved portion 9, and the curvature radius r1 of the inner curved portion 10 is 15 mm or more and 35 mm or less. Thus, by providing the inner curved portion 10 having a relatively gently curved shape inside the outer curved portion 9 of the corner portion 4a, the thickness of the rising portion of the corner portion 4a is reduced by the blow molding process. Excess can be suppressed. That is, the provision of the inner curved portion 10 delays the timing at which the parison resin comes into contact with the inner curved portion 10 of the bottom wall of the mold during the blow molding process. Therefore, it is possible to reduce the amount of resin that is solidified before the parison resin contacts the raised portion of the corner portion 4a, and to ensure a sufficient amount of resin that reaches the raised portion (the outer curved portion 9) without being cooled and solidified. Therefore, the wall thickness of the rising portion can be appropriately secured. As a result, it is possible to secure an appropriate thickness in the rising portion of the corner portion 4a, so that it is possible to suppress the lack of rigidity around the corner portion 4a.

In addition, since the inner curved portion 10 located radially inward of the ground surface forming portion 7 is not exposed to the outside when the container 1 is grounded in the upright posture shown in FIGS. There is no That is, the provision of the inner curved portion 10 on the container 1 does not increase restrictions on the appearance design. In addition, since the radius of curvature r2 of the outer curved portion 9 is smaller than the radius of curvature r1 of the inner curved portion 10, it is possible to realize a sharp design of the rising portion of the corner portion 4a.

In addition, in the container 1 of the present embodiment, it is more preferable that the curvature radius r1 of the inner curved portion 10 is 20 mm or more and 30 mm or less. It is possible to suppress the thinning of the rising portion of the corner portion 4a located at a distant position and prevent insufficient rigidity.

Further, in the container 1 of the present embodiment, the corners 4a are sharp. That is, in the bottom view shown in FIG. 3, the angle θ at which the extended lines of the sides (outer edge contour lines) 6a and 6b on both sides of the corner 4a intersect is less than 90°. Thus, when the corner 4a has an acute angle, the rising portion of the corner 4a tends to be especially thin. It is particularly effective to provide

Moreover, it is preferable that the radius of curvature r3 of the curved portion 5a provided at the corner portion 4a is 1 mm or more and 6 mm or less in the bottom view shown in FIG. If the radius of curvature r3 is 6 mm or less, the rising portion of the corner 4a tends to be thin, so it is more effective to provide the inner curved portion 10 with a large radius of curvature r1 like the container 1 of the present embodiment. Become. In addition, since the radius of curvature r3 is 1 mm or more, while the design of the corner portion 4a is sharp, it is possible to suppress the rising portion of the corner portion 4a from becoming thin and lacking rigidity at a higher level. can. More preferably, the radius of curvature r3 is 1.5 mm or more and 5.5 mm or less. Also, if the radius of curvature r3 is less than 1 mm, molding may become difficult.

In the container 1 of the present embodiment, the inner curved portion 10 of the body portion 3 and the bottom portion 4 can have an average thickness of 0.2 mm or more and 1.5 mm or less, but is not limited to this. do not have.

What has been described above merely shows an example of the present invention, and various modifications can be made within the scope of the claims. For example, the container 1 described above has a single-layer structure in which the body portion 3 and the bottom portion 4 are composed of a single layer. A double container having an outer layer body and an inner layer body provided so as to be capable of volume reduction and deformation inside the outer layer body may be used. Further, the shape of the bottom portion 4 is not limited to a quadrangle, and may be a triangle or a polygon having pentagonal or more corners as long as it is a polygon having at least one pair of corners facing each other across the parting line PL.

1: Blow-molded container 2: Mouth 2a: Opening 2b: Male screw 3: Body 3a: Shoulder 3b: Body 3c, 3d, 3e, 3f: Corners of body 4: Bottom 5a, 5b , 5c, 5d: curved portions 6a, 6b: bottom sides (outer edge contour lines)
7: Ground plane forming part 8: Raised bottom part 9: Outer curved part (rising part)
10: Inner curved portion 11: Central bottom wall portion r1: Curvature radius of inner curved portion r2: Curvature radius of outer curved portion r3: Curvature radius of curved portion provided at corner O: Axis PL: Parting line S: accommodation space

Claims (3)

A blow-molded container having a cylindrical mouth, a body connected to the mouth, and a bottom closing the lower end of the body,
The bottom has a polygonal shape in bottom view and has at least a pair of corners facing each other across a parting line of the bottom,
Of the pair of corners, the corner located farthest from the parting line has an arc-shaped outward curve extending from the lower end of the trunk to the ground contact surface forming portion of the bottom when viewed in longitudinal section. and an arc-shaped inner curved portion continuous to the inner side of the outer curved portion,
the radius of curvature of the inner curved portion is greater than the radius of curvature of the outer curved portion;
The curvature radius of the inner curved portion is 15 mm or more and 35 mm or less ,
A blow-molded container , wherein the curvature radius of the outer curved portion is 1 mm or more and 4 mm or less . 2. The blow-molded container according to claim 1 , wherein a corner portion furthest from the parting line in the bottom view has an acute angle. 2. An arc-shaped curved portion is provided at a corner located farthest from the parting line in the bottom view, and the radius of curvature of the curved portion is 1 mm or more and 6 mm or less. 3. or the blow-molded container according to 2 .

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