JP2021008273A - Flat bottle, and method for manufacturing flat bottle - Google Patents

Abstract

To deform a pair of long side portions by the same amount toward an inside in a radial direction, when the pressure is reduced.SOLUTION: A flat bottle is provided with an elastically deformable body portion 13 having a pair of short side portions 15 and a pair of long side portions 16 and exhibiting a rectangular shape, in a cross-sectional view orthogonal to a bottle axis O. The long side portion has a convex curved surface shape that bulges outward in the radial direction in the cross-sectional view, and the wall thickness at the same position in the bottle axial direction is equalized over the entire length in the circumferential direction, in the body portion, and horizontally long panel surface portions 17 that are recessed inward in the radial direction and whose size in the circumferential direction is larger than the size in the bottle axis direction are separately provided respectively, on the outer peripheral surfaces of the pair of long side portions.SELECTED DRAWING: Figure 1

Description

The present invention relates to a flat bottle and a method for producing a flat bottle.

Conventionally, for example, as shown in Patent Document 1 below, an elastically deformable body portion having a rectangular shape having a pair of short side portions and a pair of long side portions is provided in a cross-sectional view orthogonal to the bottle axis. Flat bottles are known.
As a flat bottle of this type, an extrusion blow container formed by blow molding a parison formed by extrusion molding is known. In general, the wall thickness of the parison is the same over the entire length in the circumferential direction at the same position in the bottle axial direction, so that the wall thickness of the short side portion is the long side due to the difference in the stretching amount during the blowing process. It is thinner than the wall thickness of the part.

Japanese Patent No. 3992988

However, in the conventional flat bottle, when the pressure is reduced, only one of the pair of long side portions is deformed inward in the radial direction, and the other one is started or progresses. Previously, the decompression state in the flat bottle had been eliminated or alleviated. As a result, when the pressure is reduced in the flat bottle, the pair of long side portions are not deformed by the same amount inward in the radial direction, and only one of the pair of long side portions is radially inward. There was a problem that so-called one-sided pulling, which is greatly deformed toward the inside of the, occurs.

The present invention has been made in consideration of such circumstances, and is a flat bottle and a flat bottle capable of deforming a pair of long side portions inward in the radial direction by an equivalent amount at the time of decompression. It is an object of the present invention to provide a manufacturing method.

In order to solve the above problems and achieve such an object, the flat bottle of the present invention is a rectangle having a pair of short side portions and a pair of long side portions in a cross-sectional view orthogonal to the bottle axis. It is provided with an elastically deformable body portion that exhibits a shape, and the long side portion exhibits a convex curved shape that bulges outward in the radial direction in the cross-sectional view, and the same position in the bottle axial direction in the body portion. The wall thickness is equal over the entire length in the circumferential direction, and the outer peripheral surface of the pair of long side portions is recessed inward in the radial direction, and the size in the circumferential direction is larger than the size in the bottle axis direction. Panel surface parts are provided separately.

According to the present invention, in the body portion, the wall thickness at the same position in the bottle axial direction is the same over the entire length in the circumferential direction, so that the wall thickness of the short side portion is thinner than the wall thickness of the long side portion. It is possible to improve the rigidity of both ends in the circumferential direction in the long side portion as compared with the conventional case. Therefore, even if only one of the pair of long side portions is deformed inward in the radial direction when the pressure is reduced in the flat bottle, the progress of this deformation is suppressed as compared with the conventional case. One of the other deformations can be initiated or advanced before the depressurized state in the flat bottle is eliminated or alleviated. As a result, when the pressure in the flat bottle is reduced, the pair of long side portions can be deformed by the same amount inward in the radial direction, and the occurrence of one-sided pulling can be suppressed.

Since the outer peripheral surfaces of the pair of long side portions are separately provided with panel surface portions that are recessed inward in the radial direction, the long side portions are evenly distributed over a wide range starting from the panel surface portion when the pressure inside the flat bottle is reduced. In addition, it can be deformed inward in the radial direction. As a result, even if only one of the pair of long side portions is deformed inward in the radial direction when the pressure is reduced in the flat bottle, the progress of the deformation is slowed down, and the progress of the deformation is slowed down. Before the depressurized state is eliminated or relaxed, the deformation of either one can be started or advanced, and the amount of deformation of each pair of long side portions toward the inside in the radial direction is easily equalized. can do.

Since the panel surface portion is formed in a horizontally long shape in which the size in the circumferential direction is larger than the size in the bottle axis direction, the circumferential end of the panel surface portion is brought closer to the circumferential end of the long side portion in the circumferential direction. be able to. Therefore, in the cross-sectional view, the step between the outer peripheral surface of the long side portion having a convex curved surface shape bulging outward in the radial direction and the peripheral end portion of the panel surface portion in the circumferential direction is formed on the panel surface portion. Even if the depth is secured, it can be kept low. This makes it possible to prevent stress from concentrating on the connection portion between the circumferential end of the panel surface and the outer peripheral surface of the long side when the pressure is reduced in the flat bottle. When the pressure is reduced, it is possible to prevent the connecting portion from being inverted and deformed inward in the radial direction.

The circumferential edge of the panel surface portion may be close to the circumferential edge of the long side portion.

In this case, since both peripheral edges of the panel surface portion in the circumferential direction are close to both peripheral edges of the long side portion in the circumferential direction, between the peripheral end portion of the panel surface portion and the outer peripheral surface of the long side portion. The step can be surely kept low.

The central portion of the panel surface portion in the bottle axial direction may be located at the central portion of the body portion in the bottle axial direction.

In this case, since the central portion of the panel surface portion in the bottle axial direction is located at the central portion of the body portion in the bottle axial direction, the long side portion is evenly spread over a wide area and inside in the radial direction when the pressure inside the flat bottle is reduced. Can be reliably deformed toward.

In the cross-sectional view, the surface of the panel surface portion may have a curved surface shape that protrudes outward in the radial direction over the entire length in the circumferential direction.

In this case, in the cross-sectional view, the surface of the panel surface portion exhibits a curved surface shape that protrudes outward in the radial direction over the entire length in the circumferential direction, as in the long side portion. Therefore, as described above, the panel surface portion Even if the depth of the panel surface is secured, the circumference of the panel surface is due to the fact that the peripheral end of the panel and the peripheral end of the long side are close to each other in the circumferential direction. It is possible to surely suppress an increase in the step between the end portion in the direction and the outer peripheral surface of the long side portion.

The method for producing a flat bottle of the present invention includes a parison forming step of forming a parison extending in the vertical direction by extrusion molding, and a state in which the parison is sandwiched in the radial direction by a pair of molding dies and the upper end opening of the parison is opened. By closing the lower end opening of the parison and positioning the parison in the cavity between the pair of molding dies, and by supplying pressurized air into the parison and stretching the parison. The parison has a blow step of forming a flat bottle of the present invention, and the parison includes a thin-walled portion and a thick-walled portion provided at different positions in the circumferential direction, and during the blow step, the thin-walled portion is provided. The long side portion may be formed, and the thick portion may be formed on the short side portion.

According to the present invention, the parison is provided with a thin-walled portion and a thick-walled portion provided at different positions in the circumferential direction, and during the blowing process, the thin-walled portion is formed into a long side portion and the thick-walled portion is formed into a short side. Mold into parts. That is, the short side portion having a large stretching amount during the blowing process is formed from the thick portion of the parison, and the long side portion having a small stretching amount during the blowing process is formed from the thin wall portion of the parison. , It is possible to surely form a flat bottle in which the wall thickness at the same position in the bottle axial direction is the same over the entire length in the circumferential direction.

According to the present invention, when the pressure in the flat bottle is reduced, the pair of long side portions can be deformed by the same amount inward in the radial direction, and such a flat bottle can be reliably formed. it can.

It is a side view seen from the minor axis direction of the flat bottle shown as one Embodiment which concerns on this invention. It is a side view seen from the long axis direction of the flat bottle shown as one Embodiment which concerns on this invention. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. FIG. 1 is a cross-sectional view taken along the line IV-IV of FIG. It is a cross-sectional view of a parison. It is a graph which shows the wall thickness distribution in the central part in the bottle axis direction of the body part.

Hereinafter, the flat bottle 1 according to the embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the flat bottle 1 has a mouth portion 11, a shoulder portion 12, a body portion 13, and a bottom portion 14 arranged in this order from top to bottom along the bottle axis O direction. It is composed of. The cross-sectional view shape orthogonal to the bottle axis O of each of the mouth portion 11 and the shoulder portion 12 is circular. The cross-sectional view shape of each of the body portion 13 and the bottom portion 14 is rectangular.
Hereinafter, the direction that intersects the bottle axis O when viewed from the bottle axis O direction is referred to as a radial direction, and the direction that orbits around the bottle axis O is referred to as a circumferential direction.

The flat bottle 1 is an extrusion blow container formed by blow molding a parison formed by extrusion molding. The flat bottle 1 is made of a synthetic resin material such as PET (polyethylene terephthalate), PP (polypropylene), PE (polyethylene), nylon (polyamide), and EVOH (ethylene-vinyl alcohol copolymer).

The contents to be filled in the flat bottle 1 include, for example, a mixture of solid and liquid, grated cheese, detergent, crush jelly, jam containing pulp and the like.
The internal volume of the flat bottle 1 is, for example, a size that can be filled with contents of 100 ml or more and 4000 ml or less. In the illustrated example, the flat bottle 1 is sized to be used to fill about 200 ml of content.

As shown in FIG. 3, the cross-sectional view shape of the body portion 13 is a rectangular shape having a pair of short side portions 15 and a pair of long side portions 16, and the body portion 13 is formed so as to be elastically deformable. ing. By pushing the pair of long side portions 16 inward in the radial direction and elastically deforming them, the contents are smoothly discharged from the mouth portion 11. The short side portion 15 and the long side portion 16 are connected in the circumferential direction via the corner portion 18. The straight line (major axis La) connecting the central portions in the circumferential direction of the pair of short side portions 15 and the straight line (minor axis Lb) connecting the central portions in the circumferential direction of the pair of long side portions 16 are the bottle axes. Crossing on O.

The size W1 of the body portion 13 in the long axis direction along the long axis La is, for example, 1.15 times or more and twice or less the size of the short axis direction W2 along the short axis Lb. The size W4 of the short side portion 15 along the short axis direction is, for example, 10 mm or more and 30 mm or less (in the illustrated example, about 19.2 mm). The size W3 of the long side portion 16 along the long axis direction is, for example, 50 mm or more and 70 mm or less (in the illustrated example, about 60.8 mm).

At least one of the short side portion 15 and the long side portion 16 extends straight over the entire length in the bottle axis O direction. As shown in FIG. 2, the long side portion 16 extends straight along the bottle axis O direction over the entire length in the bottle axis O direction. As shown in FIG. 1, of the short side portions 15, the upper end portion extends inward in the radial direction as it goes upward, and the portion located below the upper end portion is along the bottle axis O direction. It extends straight.

The short side portion 15 may extend straight along the bottle axis O direction over the entire length in the bottle axis O direction. The upper end portion of the long side portion 16 may extend inward in the radial direction as it goes upward, and the portion located below the upper end portion may extend straight along the bottle axis O direction.
Here, the bottom portion 14 is formed in a flat cup shape, and the outer peripheral surface of the bottom portion 14 extends inward in the radial direction as it goes downward.

The wall thickness of the body portion 13 is, for example, 0.2 mm or more and 0.8 mm or less, preferably 0.4 mm or more and 0.6 mm or less. In the body portion 13, the wall thickness at the same position in the bottle axis O direction is the same over the entire length in the circumferential direction. That is, at the same position in the body portion 13 in the bottle axis O direction, the minimum value of the wall thickness is, for example, 80% or more and 100% or less of the maximum value of the wall thickness.

As shown by the solid line in FIG. 6, the minimum value of the wall thickness is about 0.46 mm and the maximum value of the wall thickness is about 0.63 mm at the central portion of the body 13 in the bottle axis O direction. The minimum value of the wall thickness is about 73% of the maximum value of the wall thickness. A to H shown in FIG. 6 correspond to the positions in the circumferential direction shown in FIG. The wall thicknesses of the short side portion 15 (C, G) and the long side portion 16 (A, E) are almost the same as each other, and the wall thickness of the corner portion 18 (B, D, F, H) is the short side portion. It is slightly thinner than each wall thickness of 15 and the long side portion 16. The wall thickness of the corner portion 18 may be equal to or greater than the wall thickness of the short side portion 15 and the long side portion 16.

As shown in FIG. 3, the cross-sectional view shape of the short side portion 15, the long side portion 16, and the corner portion 18 is a convex curved surface shape that bulges outward in the radial direction. The cross-sectional view shape of the short side portion 15 may extend straight along the short axis direction.
In the cross-sectional view, the radius of curvature of the long side portion 16 is the largest and the radius of curvature of the corner portion 18 is the smallest among the short side portion 15, the long side portion 16, and the corner portion 18. In the cross-sectional view, the radius of curvature of the long side portion 16 is, for example, 50 mm or more and 200 mm or less.

On the outer peripheral surfaces of the pair of long side portions 16, horizontally long panel surface portions 17 that are recessed inward in the radial direction and whose size in the circumferential direction is larger than the size in the bottle axis O direction are separately provided. The circumferential edge 17a of the panel surface portion 17 is close to the circumferential edge 16a of the long side portion 16. The distance X along the long axis direction between the circumferential edge 17a of the panel surface portion 17 and the circumferential edge 16a of the long side portion 16 is, for example, 5.0 mm or less (in the illustrated example, about 1.5 mm). ). This interval X is, for example, 12% or less, preferably 8% or less, more preferably 3% or less (about 2.5% in the illustrated example) of the size W3 in the long axis direction in the long side portion 16. ing.

As shown in FIG. 1, the panel surface portion 17 exhibits a horizontally long elliptical shape when viewed from the minor axis direction. The shape of the panel surface portion 17 when viewed from the minor axis direction may be, for example, a horizontally long rectangular shape, a circular shape, or the like. The size of the panel surface portion 17 in the major axis direction is, for example, 1 times or more and 6 times or less the size of the panel surface portion 17 in the bottle axis O direction.

The central portion of the panel surface portion 17 in the bottle axis O direction is located at the central portion of the body portion 13 in the bottle axis O direction. In the illustrated example, the central portion of the panel surface portion 17 coincides with the central portion of the long side portion 16 when viewed from the short axis direction. When viewed from the short axis direction, the central portion of the panel surface portion 17 may be displaced in the circumferential direction or may be displaced in the bottle axis O direction with respect to the central portion of the long side portion 16.

As shown in FIG. 3, in a cross-sectional view orthogonal to the bottle axis O, the surface of the panel surface portion 17 facing outward in the radial direction has a curved surface shape protruding outward in the radial direction over the entire length in the circumferential direction. Present. In the cross-sectional view, the peripheral edge 17a of the panel surface 17 is continuously connected to the peripheral edge of the long side portion 16 in the circumferential direction without a step. In the cross-sectional view, the radius of curvature of the surface of the panel surface portion 17 is larger than the radius of curvature of the outer peripheral surface of the long side portion 16.
As shown in FIG. 4, in a vertical cross-sectional view along the bottle axis O, the surface of the panel surface portion 17 exhibits a curved surface shape that is recessed inward in the radial direction over the entire length in the bottle axis O direction.

Next, a method for manufacturing the flat bottle 1 configured as described above will be described.

First, parison W is formed by extrusion molding (parison forming step). At this time, the parison W is extruded downward from the die head and extends in the vertical direction. Hereinafter, the central axis of the parison W will be referred to as the bottle axis O described above.
As shown in FIG. 5, the parison W includes a thin-walled portion W1 and a thick-walled portion W2 provided at different positions in the circumferential direction. The thin-walled portion W1 is the thinnest portion of the parison W, and the thick-walled portion W2 is the thickest portion of the parison W. The thin portion W1 and the thick portion W2 are located about 90 ° apart from the bottle axis O. When viewed from the bottle axis O direction, the outer peripheral surface of the parison W has a circular shape, and the inner peripheral surface of the parison W has an elliptical shape. The wall thickness of the parison W becomes thicker from the thin wall portion W1 to the thick wall portion W2 along the circumferential direction.
Instead of the parison W, a parison having an elliptical outer peripheral surface and a circular inner peripheral surface when viewed from the bottle axis O direction may be adopted.

Next, the parison W extruded from the die head is sandwiched in the radial direction by a pair of molding dies, the lower end opening of the parison W is closed with the upper end opening of the parison W open, and the parison W is molded into a pair. Positioned in the cavity between the molds (molding process).
At this time, the thin-walled portion W1 faces the portion of the inner surface of the cavity where the long side portion 16 is molded, and the thick-walled portion W2 faces the portion of the inner surface of the cavity where the short side portion 15 is molded. As a result, the distance between the outer peripheral surface of the thin-walled portion W1 and the portion of the inner surface of the cavity where the long side portion 16 is formed is the outer peripheral surface of the thick-walled portion W2 and the short side portion 15 of the inner surface of the cavity. It is narrower than the distance between the part to be molded.

Next, pressurized air is supplied into the parison W to extend the parison W and press it against the inner surface of the cavity. At this time, the thin-walled portion W1 is pressed against the portion of the inner surface of the cavity where the long-side portion 16 is to be molded to form the long-side portion 16, and the thick-walled portion W2 presses the short-side portion 15 of the inner surface of the cavity. The short side portion 15 is formed by being pressed against the portion to be molded (blow step). From the above, the flat bottle 1 is formed.
At the time of the mold clamping step, the plug is inserted into the parison W from the upper end opening to be fitted, and the upper part of the parison W is sandwiched between the outer peripheral surface of the plug and the inner surface of the cavity, and the mouth portion 11 of the flat bottle 1 is inserted. Pressurized air may be supplied into the parison W through the supply holes formed in the plug during the molding and then the blowing step.

As described above, according to the flat bottle 1 according to the present embodiment, in the body portion 13, the wall thickness at the same position in the bottle axis O direction is the same over the entire length in the circumferential direction, so that the short side portion 15 Compared with the conventional case in which the wall thickness of the long side portion 16 is thinner than the wall thickness of the long side portion 16, the rigidity of both ends in the circumferential direction of the long side portion 16 can be improved. Therefore, even if only one of the pair of long side portions 16 is deformed inward in the radial direction when the pressure is reduced in the flat bottle 1, the progress of this deformation is suppressed as compared with the conventional case. Therefore, the deformation of either one can be started or promoted before the depressurized state in the flat bottle 1 is eliminated or alleviated. As a result, when the pressure in the flat bottle 1 is reduced, the pair of long side portions 16 can be deformed by the same amount toward the inside in the radial direction, and it is possible to suppress the occurrence of one-sided pulling. ..

Since the panel surface portions 17 that are recessed inward in the radial direction are separately provided on the outer peripheral surfaces of the pair of long side portions 16, the long side portions start from the panel surface portion 17 when the pressure inside the flat bottle 1 is reduced. 16 can be deformed evenly over a wide area inward in the radial direction. As a result, even if only one of the pair of long side portions 16 is deformed inward in the radial direction when the pressure is reduced in the flat bottle 1, the progress of the deformation is slowed down, and the flat bottle Before the decompression state in 1 is eliminated or alleviated, the deformation of either one can be started or advanced, and the amount of deformation of each of the pair of long side portions 16 toward the inside in the radial direction can be determined. It can be easily equalized.

Since the panel surface portion 17 is formed in a horizontally long shape in which the size in the circumferential direction is larger than the size in the bottle axis O direction, the peripheral end portion of the panel surface portion 17 is set to the circumferential end portion of the long side portion 16. It can be approached in the circumferential direction. Therefore, in the cross-sectional view, the step between the outer peripheral surface of the long side portion 16 having a convex curved surface shape protruding outward in the radial direction and the peripheral end portion of the panel surface portion 17 in the circumferential direction is formed on the panel. Even if the depth of the surface portion 17 is secured, it can be kept low. This makes it possible to prevent stress from concentrating on the connecting portion between the circumferential end of the panel surface portion 17 and the outer peripheral surface of the long side portion 16 when the pressure is reduced in the flat bottle 1, and the flatness is flat. It is possible to prevent this connecting portion from being inverted and deformed inward in the radial direction when the pressure inside the bottle 1 is reduced.

Since the circumferential end edges 17a of the panel surface portion 17 are close to the circumferential end edges 16a of the long side portion 16, the peripheral end portion of the panel surface portion 17 in the circumferential direction and the outer peripheral surface of the long side portion 16 The step between them can be surely kept low.

Since the central portion of the panel surface portion 17 in the bottle axis O direction is located at the central portion of the body portion 13 in the bottle axis O direction, the long side portion 16 has a uniform diameter over a wide range when the pressure inside the flat bottle 1 is reduced. It can be reliably deformed inward in the direction.

In the cross-sectional view, the surface of the panel surface portion 17 exhibits a curved surface shape that protrudes outward in the radial direction over the entire length in the circumferential direction, as with the long side portion 16, and therefore, as described above, the panel surface portion 17 Even if the depth of the panel surface portion 17 is secured, the panel surface portion is combined with the fact that the peripheral end portion of the panel surface portion 16 and the circumferential end portion of the long side portion 16 are brought close to each other in the circumferential direction. It is possible to reliably suppress an increase in the step between the end portion in the circumferential direction of 17 and the outer peripheral surface of the long side portion 16.

According to the method for manufacturing a flat bottle 1 according to the present embodiment, the parison W includes a thin-walled portion W1 and a thick-walled portion W2 provided at different positions in the circumferential direction, and lengthens the thin-walled portion W1 during the blowing step. It is molded into the side portion 16 and the thick portion W2 is formed into the short side portion 15. That is, the short side portion 15 having a large stretching amount during the blowing step is formed from the thick portion W2 of the parison W, and the long side portion 16 having a small stretching amount during the blowing step is formed from the thin portion W1 of the parison W. Therefore, in the body portion 13, the flat bottle 1 having the same wall thickness at the same position in the bottle axis O direction over the entire length in the circumferential direction can be reliably formed.

The present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the spirit of the present invention.

For example, in the embodiment, in the cross-sectional view, the surface of the panel surface portion 17 has a curved surface shape that protrudes outward in the radial direction over the entire length in the circumferential direction, but is directed inward in the radial direction. It may have a curved surface with a protrusion, or it may extend in a straight line.
In the cross-sectional view, the peripheral edge 17a of the panel surface portion 17 may be connected to the peripheral end portion of the long side portion 16 in the circumferential direction via a step portion.

The flat bottle 1 is not limited to a single-layer structure, but may be a laminated structure having an intermediate layer. Examples of the intermediate layer include a layer made of a resin material having a gas barrier property, a layer made of a recycled material, a layer made of a resin material having an oxygen absorption property, and the like.

In addition, it is possible to replace the constituent elements in the above-described embodiment with well-known constituent elements as appropriate without departing from the spirit of the present invention, and the above-mentioned modified examples may be appropriately combined.

Next, the verification test will be described.

First, a flat bottle was formed by using a parison having the same mass as the parison W having the thin-walled portion W1 and the thick-walled portion W2 shown in the above embodiment and having the same wall thickness over the entire circumference.
In this flat bottle, as shown by the broken line in FIG. 6, the minimum wall thickness is about 0.32 mm and the maximum wall thickness is about 0.83 mm at the center of the body in the bottle axis direction. It was confirmed that the minimum value of the wall thickness was about 38.6% of the maximum value of the wall thickness. The wall thicknesses of the short side portion (C, G) and the corner portion (B, D, F, H) are almost the same as each other, and the wall thickness of the long side portion (A, E) is the short side portion and the corner portion. It is about twice as thick as each wall thickness of.

Next, for a plurality of types of flat bottles having different intervals X, the difference in the amount of deformation of the pair of long side portions toward the inside in the radial direction in the process of decreasing the internal pressure was confirmed by numerical analysis.
As the first embodiment, a flat bottle 1 having the interval X of about 1.53 mm (about 2.5% of the size W3 in the long axis direction in the long side portion 16) is adopted, and as the second embodiment, the interval X is A flat bottle of about 5.04 mm (about 8.3% of the size W3 in the long axis direction in the long side portion 16) is adopted, and as Comparative Example 1, the interval X is about 14.0 mm (in the long side portion 16). A flat bottle with a size (about 23.0% of the size W3 in the long axis direction) and a circular shape of the panel surface when viewed from the short axis direction was adopted.

As a result, in Examples 1 and 2, it was confirmed that in the process of lowering the internal pressure, the difference in the amount of deformation of the pair of long side portions toward the inside in the radial direction once increased and then decreased. That is, even if only one of the pair of long side portions is deformed inward in the radial direction during decompression in the flat bottle, before the decompression state in the flat bottle is eliminated or alleviated. , It was confirmed that the deformation of either one started or progressed.
In Comparative Example 1, when the pressure in the flat bottle is reduced, only one of the pair of long side portions is deformed inward in the radial direction, and the other one is before the start or progress of the deformation. It was confirmed that the decompression state in the flat bottle was eliminated or alleviated.
In the first embodiment, it is confirmed that the connecting portion between the circumferential end portion of the panel surface portion 17 and the outer peripheral surface of the long side portion 16 does not reversely deform toward the inner side in the radial direction even if the internal pressure drops significantly. Was done.

1 Flat bottle 11 Mouth 12 Shoulder 13 Body 14 Bottom
15 Short side part 16 Long side part 16a Circumferential edge on long side 17 Panel surface 17a Circumferential edge on panel surface O Bottle shaft W Parison W1 Thin wall part W2 Thick part

Claims (5)

It has an elastically deformable body that has a rectangular shape with a pair of short sides and a pair of long sides in a cross-sectional view orthogonal to the bottle axis.
The long side portion has a convex curved surface shape that bulges outward in the radial direction in the cross-sectional view.
In the body, the wall thickness at the same position in the bottle axial direction is equalized over the entire length in the circumferential direction.
A flat bottle in which a horizontally long panel surface portion that is recessed inward in the radial direction and whose size in the circumferential direction is larger than the size in the bottle axis direction is separately provided on the outer peripheral surface of the pair of long side portions. The flat bottle according to claim 1, wherein the peripheral edge of the panel surface portion is close to the circumferential edge of the long side portion. The flat bottle according to claim 1 or 2, wherein the central portion of the panel surface portion in the bottle axial direction is located at the central portion of the body portion in the bottle axial direction. The flat bottle according to any one of claims 1 to 3, wherein the surface of the panel surface portion exhibits a curved surface shape that protrudes outward in the radial direction over the entire length in the circumferential direction in the cross-sectional view. A parison forming process that forms a parison that extends in the vertical direction by extrusion molding,
The parison is sandwiched in the radial direction by a pair of molding dies, the lower end opening of the parison is closed with the upper end opening of the parison open, and the parison is positioned in the cavity between the pair of molding dies. Molding process and
It has a blow step of forming a flat bottle according to any one of claims 1 to 4 by supplying pressurized air into the parison and stretching the parison.
The parison has a thin-walled portion and a thick-walled portion provided at different positions in the circumferential direction.
A method for producing a flat bottle, in which the thin-walled portion is molded into the long-sided portion and the thick-walled portion is molded into the short-sided portion during the blowing step.

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