JP3138051B2 - Self-standing container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic container having good self-supporting properties, and more particularly to a plastic container having a so-called petaloid-shaped bottom integrally formed so as to be self-supporting without using a base cup. Plastic container.

[0002]

2. Description of the Related Art A biaxially stretched blow-molded container made of a saturated polyester resin represented by polyethylene terephthalate has excellent transparency and surface gloss, is beautiful, and has a gas barrier. Excellent in water resistance, moisture impermeability, content resistance and storage stability. In addition, it has many advantages such as low heat generation during combustion and easy disposal because it does not damage the furnace. Therefore, it is widely used for various drinking water, seasonings, alcoholic beverages and other food containers.

Some of such biaxially stretch blow-molded containers (bottles) have a so-called base cup mounted on the bottom. The base cup is mounted to provide autonomy to the container and, in some cases, to reinforce the bottom, which is often used, for example, for containers whose contents have a high internal pressure, such as carbonated beverages. This is because in such a container, the bottom of the container is generally formed into a rounded convex shape in order to improve the internal pressure resistance.

Although the above-described container with a base cup has excellent self-standing stability and the bottom is reinforced, the number of steps of manufacturing the base cup in a separate process and then attaching it to the container main body increases, thereby increasing productivity. Inferior. Further, since the base cup is usually formed of a different kind of resin from the container body, the container provided with the base cup is inferior in recyclability.

Therefore, a container having a structure in which various irregularities are formed on the bottom of the container to reinforce the bottom of the container and ensure independence without a base cup (for example, JP-A-61-9).
No. 170, JP-A-2-57545, etc.) have been developed and put to practical use.

JP-A-61-9170 discloses a container as shown in FIG. 6 as a typical example. In FIG. 6, (a) is a side view of the container, and (b) is a longitudinal sectional view at the bottom of the container shown in (a). As can be seen from FIG. 6, the bottom structure of the container according to JP-A-61-9170 is as follows.
A plurality of flat portions (for example, flat portions such as the ground contact portion 61 and the leg side portions 62 and 63) are combined to form the leg portion 60. With such a bottom structure, when a high internal pressure is applied to the container, stress is applied to the ridges (corners), which are boundaries between the flat portions, and uneven deformation is likely to occur therefrom.

On the other hand, Japanese Patent Application Laid-Open No. 2-57545 discloses a container having a bottom shape as shown in FIG. 7 as a typical example. In FIG. 7, (a) is a side view of the container, and (b) is a longitudinal sectional view at the bottom of the container shown in (a). At the bottom 71 of the container 70 is positioned slightly inward than the diameter r ₀ of the barrel portion of the container grounding portion 74 which is formed at the lower end of the leg portion 72 (i.e. the diameter r ₁ of the ground portion 74 formed and as much as possible close to r ₀₎ as, thereby improving the self-supporting stability. In the example shown in FIG.
Since the number of legs of the container is 5, an imaginary leg 72 'is drawn in the vertical sectional view of the bottom shown in FIG.

In Japanese Patent Application Laid-Open No. 2-57545, the lower end surface 75 of the leg 71 is formed so as to be slightly upwardly inclined inward from the ground contact portion 74, so that the container can be filled at the time of filling. When the internal pressure is increased, the inclined lower end face 75 is pushed downward by the internal pressure and becomes substantially horizontal, so that the horizontally deformed lower end face comes into surface contact with the container supporting surface, and the self-standing stability (when filling the container) is obtained. Is described as being better.

However, according to the study of the present inventors, according to Japanese Patent Application Laid-Open No. 2-57545, the diameter (r ₁ in FIG. 7) formed by the grounding portion is made as close as possible to the (maximum) trunk diameter (r ₀ ). In this case, the self-standing stability of the container is not so good, and the self-standing stability of an empty container having a high center of gravity is particularly poor. Rather, the self-supporting stability of the container depends on the circumferential width of the ground contact. Independence stability at the time of non-filling is extremely important in the work of filling the container with contents, etc., and if this is impaired, the line feedability of the container will be deteriorated, and the filling work of the contents will not be performed smoothly . In addition, even if the lower end surface of the inclined leg becomes substantially horizontal due to the internal pressure when the contents are filled, the lower end surface does not necessarily come into close contact with the container support surface in all the legs, The self-standing stability at the time of filling the container is not always good. In order to improve the self-standing stability at the time of filling, it is important to specify the position of the ground contact portion on the lower end surface.

Accordingly, an object of the present invention is to provide an integrally molded pressure-resistant container that does not use a base cup, and that has good self-standing stability both when the container is filled and when it is not filled.

[0011]

In order to solve the above-mentioned problems, as a result of earnest studies on a pressure-resistant self-standing container having a bottom portion formed integrally with a plurality of legs forming a grounding portion, the present invention has been achieved. The person forms a flat circumferentially wide ground contact surface portion that contacts the container support surface when the container is not filled, on the outer portion of the lower end surface of each leg portion, and on the container inner side of this contact surface portion,
The leg structure has a substantially flat inclined surface that slopes upward toward the inside of the container continuously with the ground surface, and the bottom wall other than the ground surface and the inclined surface has a smooth curved surface. It has been found that a pressure-resistant self-standing container having good self-standing stability can be obtained both when the container is filled and when the container is not filled, and the present invention has been completed.

In other words, the pressure-resistant self-standing container of the present invention having a bottom in which a plurality of legs forming a grounding portion are formed integrally and at equal intervals in the circumferential direction is provided at the outer portion of the lower end surface of each leg. A flat contact surface portion that is wide in the circumferential direction and is in contact with the container supporting surface when the container is not filled, and the contact surface portion is provided on the inner side of the container and is continuous with the contact surface portion. A substantially flat inclined surface portion inclined upward toward the inside of the container is formed, and the bottom wall other than the ground contact surface portion and the inclined surface portion is characterized by that a smooth curved surface portion is continuous. I do.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIG. 1 shows a bottom structure of a pressure-resistant self-standing container 1 according to one embodiment of the present invention, wherein (a) is a bottom view and (b)
FIG. 2 is a sectional view taken along line AA of FIG.

Although only the bottom structure of the container 1 is shown in FIG. 1, the shape of the portion other than the bottom, such as the mouth, shoulder, and trunk, of the container 1 may be changed according to the purpose of use of the container. It may be appropriately set to various shapes found in conventional plastic containers. A feature of the container of the present invention is its bottom shape.

In the embodiment shown in FIG. 1, at the bottom of the container 1,
Five legs 10 are formed at equal intervals in the circumferential direction. Each leg 10 is smoothly continuous from the body wall of the container and has an outwardly convex outer surface 15 having a large radius of curvature.
An outwardly projecting corner 16 having a small radius of curvature continuous with the lower end of the outer side surface portion 15; a ground contact surface portion 11 which comes into surface contact with the container support surface when the container is not filled; And a continuous inclined surface portion 13. Slope 13
Is substantially flat (planar), and is inclined upward toward the inside of the diameter. Although the angle of inclination of the inclined surface portion depends on the size of the container, the distance d (the ground contact surface portion 1) shown in FIG.
1 to the lowermost end of the central curved portion 19 described later)
It is preferable to set the angle to 5 mm (specifically, 20 to 30 °).

Inside the inclined surface 13 of each of the legs 10 at the bottom, a smooth curved surface 17 which is convex inwardly (upward) of the container is formed, and further inside the curved surface 17, the center of the bottom is formed. A smooth central curved surface portion 19 that includes O and is convex downward is formed.

As will be described in detail later, the bottom side surface portion 18 between the legs 10 has a vertical section along the axis of the container.
As shown in FIG. 1 (b), it has an outwardly convex curved surface having a large radius of curvature, and is smoothly continuous with the central curved surface portion 19 and connected to the container body.

In FIG. 1B, the broken line shows a cross section along the line OB in FIG. 1A, and shows the leg 10 'in this cross section.

FIGS. 2A and 2B show the unevenness of the container wall on the bottom lower surface near the leg 10, wherein FIG. 2A is a bottom view of the container, and FIG. 2B is a bottom view of the container as shown in FIG. Perpendicular to the radial axis Or at equal intervals (straight lines a, b, c,...).
FIG. 7 is a diagram showing what the bottom wall surface is in an irregular state along lines a, b, c,. For example
When the vicinity of the leg 10 is cut by the line a in (a), a point P on the bottom wall shown in (a) (the bottom side surface 1 away from the leg 10) is obtained.
8) is located on the line a, and is located above the container by a distance s shown in (b) from the point P ₀ located at the outer edge of the leg 10.

Lines a, b, c,... Shown in FIG. 2B correspond to the straight lines a, b, c,.
Has a horizontal straight line in the vicinity of the axis Or (that is, in the vicinity of the center of the lower surface of the leg 10), and is inclined downward at a portion off the leg 10. Here, each point on the downwardly inclined line portion indicates that the point is located above the container from the lower surface of the leg 10 as described above.

In FIG. 2B, each line a, b, c.
Tangent lines (straight lines a ', b', c ',...) Near the lower surface of the leg portion 10 and a tangent line (straight line a ") at an inclined line portion deviating from the leg portion 10. , B ″,
) (the intersection of a straight line a 'and a straight line a ", the intersection of a straight line b' and a straight line b", the intersection of a straight line c 'and a straight line c ".
The curve L connecting... Is a boundary (contour) of the lower end face of the leg 10.
It will be an indication of In other words, the area sandwiched by the pair of curves L, L is the lower end surface of the leg portion 10, and the lower end surface is formed with the ground contact surface portion 11, as can be seen from FIG. The outer portion is wide, gradually narrows toward the inside of the container, and has a shape that closes outside the center O of the bottom of the container.

Bottom side 1 between adjacent legs 10, 10
The concavo-convex state of No. 8 will be described in the same manner as described above. 3A is a bottom side view of the container 1, and FIG.
As shown in (a), when the bottom side is cut horizontally (at straight lines a, b, c,...) at equal intervals, lines a, b, c
It is a figure which shows what kind of uneven | corrugated state (in the radial direction) is a side part along *. For example, when the vicinity of the side 18 between the adjacent legs 10 and 10 is cut by the straight line a in (a), the point P located on the side near the one leg 10 is located in the middle of the two legs 10 and 10. It is located outside the container by the distance s shown in (b) from the located point P ₀ .

As shown in FIG. 2B, in FIG. 3B, a tangent line (for example, a straight line a 'in the line a) in the curved portion on the bottom side surface portion 18 side and an outer surface of the leg portion 10 are formed. From the intersection with the tangent (the straight line a ″ in the line a) in the curved portion on the side, the bottom side surface portion 1 between the adjacent legs 10, 10
When a line serving as a guide of the boundary between the outer surface portion 15 of the leg 10 and the line 8 is obtained, the curves L and L shown in FIG. 3B are obtained.
As can be seen from the figure, the curves L, L are parabolic curves concave on the bottom side surface portion 18 side.

The cross section taken along the line CC shown in FIG. 3A is the cross section previously shown in FIG. 1B.

Similarly, looking at the irregularities near the outer surface 15 of the leg 10, the straight lines a, b, and c shown in FIG.
The state of the unevenness along... Is as shown in FIG. 2 and 3, tangents a ', b', c '
··· and tangents a ″, b ″, c ″.
When L is obtained, it becomes a curve as shown in FIG. The portion sandwiched between the curves L, L (the outer surface 15 of the leg 10)
) Has a divergent shape as it goes upward from the lower end of the leg 10. This is the same as
It qualitatively agrees with the curves L and L shown in FIG.

As described above, (the outer surface 15 of the leg 10)
Is formed so as to expand toward the top, the strength of the container bottom portion against external force in the vertical direction becomes good. Also, when an internal pressure is applied, no significant deformation occurs in the legs.

As described above, in the container of the present invention, the grounding surface portion 11 and the inclined surface portion 13 inside the grounding surface portion 11 are substantially flat, but all other bottom walls are formed by combining smooth curved surfaces. There are no sharp corners (ridges) in the boundary area between the surfaces including the ground plane 11 and the inclined plane 13. Therefore, even if the internal pressure of the container is increased, there is no deformation that impairs the self-standing stability.

Further, in the container of the present invention, when the container is not filled, a wide contact surface portion is provided in the circumferential direction in surface contact with the container support surface, so that the self-standing stability at the time of non-filling is remarkably improved. In particular, as shown in FIG. 2B, if the outer portion of the lower end surface of the leg (the portion having the contact surface) is formed widely, the contact surface can also be formed to be long laterally, and the self-sustaining stability can be improved. Is further improved. The width of the grounding surface along the circumferential direction is preferably about 30 to 40% of the total circumference.

When the above-mentioned container is filled with contents such as carbonated beverages, the bottom is slightly deformed by the internal pressure. FIG. 5 shows a typical example of the deformation of the container 1 of the embodiment described above due to the internal pressure. FIG. 5 is a longitudinal sectional view of the bottom of the container 1,
The solid line shows the shape of the bottom when no filling is performed, and the broken line 20 schematically shows the deformation state when the container is filled with the contents and an internal pressure is applied. In FIG. 5, the degree of deformation at the time of filling the container is exaggerated for explanation. When an internal pressure is applied, the contact surface portion 11 and the inclined surface portion 13 move downward, respectively, and are transformed into the surface portions 21 and 23. In this case, the boundary portion P between the surface portions 21 and 23 becomes the grounding portion of the container. In the present invention, since the inclined surface portion 13 inside the ground contact surface portion 11 at the time of no filling is made substantially flat,
Even when the lower end of the leg is deformed downward as shown by the broken line in FIG. 5, the boundary portion P between the flat surface portions 21 and 23 is definitely specified as the ground contact portion. If the inclined surface portion 13 is a curved surface that is convex downward (at the time of non-filling), when the lower end portion of the leg is deformed downward, the curved surface portion that is downwardly convex that the inclined surface portion 13 is deformed. Becomes a ground contact portion at the time of bottom deformation (at the time of filling), and good self-standing stability cannot be obtained. In addition, if the inclined surface portion 13 at the time of non-filling is a curved surface portion which is convex upward, it is not preferable because the portion may be inverted due to the internal pressure.

As can be seen from the above, the container according to the present invention has good self-standing stability not only when no contents are filled but also when contents are filled.

While the container having five legs has been described with reference to the accompanying drawings, the number of legs is not limited to this, and may be variously changed. Preferably, the number of legs is 3 to 6, but in consideration of self-supporting stability and internal pressure resistance, a container having five legs is more preferable. If the number of legs is too large, the strength of the bottom side wall between adjacent legs may be reduced.

As the resin forming the container, a polyester resin is preferable. As the polyester resin, a thermoplastic resin comprising a saturated dicarboxylic acid and a saturated dihydric alcohol can be used. As the saturated dicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-
4,4'-dicarboxylic acid, diphenyldicarboxylic acids, aromatic dicarboxylic acids such as diphenoxyethanediethanedicarboxylic acids, adipic acid, sebacic acid, azelaic acid, aliphatic dicarboxylic acids such as decane-1,10-dicarboxylic acid, An alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid can be used. Examples of the saturated dihydric alcohol include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol,
Aliphatic glycols such as polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, neopentyl glycol, alicyclic glycols such as cyclohexane dimethanol, 2,2-bis (4'-β-hydroxyethoxyphenyl )
Propane, other aromatic diols and the like can be used. A preferred polyester is polyethylene terephthalate consisting of terephthalic acid and ethylene glycol.

The polyester resin has an intrinsic viscosity of 0.5 to 1.5.
, Preferably in the range 0.55 to 0.8. Also, such polyesters are produced by melt polymerization,
Those subjected to a reduced pressure treatment or a heat treatment in an inert gas atmosphere at a temperature of 250 ° C., or those subjected to solid phase polymerization to reduce the content of oligomers and acetaldehyde, which are low molecular weight polymers, are preferred.

In the polyester resin, additives such as stabilizers, pigments, antioxidants, heat deterioration inhibitors, ultraviolet light deterioration inhibitors, antistatic agents, antibacterial agents and the like are provided as long as the object of the present invention is not impaired. Can be added in an appropriate amount.

Although the present invention has been described with reference to the accompanying drawings, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention. For example, the shape and number of the legs are appropriately set in consideration of the purpose of use and design of the container.

[0037]

As described above in detail, the legs integrally provided on the bottom of the container of the present invention have a wide grounding surface portion in the circumferential direction which makes surface contact with the container supporting surface when the container is not filled. The self-standing stability at the time of non-filling is greatly improved as compared with a conventional container of the same kind.

The ground surface and the bottom wall other than the part immediately inside the ground surface are formed by smoothly connecting a plurality of curved surfaces and have no sharp corners. Therefore, even if the internal pressure increases, there is no deformation that impairs independence.

Furthermore, in the container according to the present invention, even when the contents are filled and the internal pressure is increased and the bottom is deformed so as to expand slightly, the boundary between the ground surface at the lower end surface of the leg and the inclined surface is grounded. Part, and the self-sustainability at the time of container filling becomes good.

The container of the present invention is suitable for containers (bottles) for various foods and beverages such as carbonated beverages.

[Brief description of the drawings]

FIG. 1 shows a bottom structure of a container according to an embodiment of the present invention, wherein (a) is a bottom view of the container and (b) is a longitudinal sectional view of the bottom of the container.

FIGS. 2A and 2B show an uneven state near a leg at the bottom of the container shown in FIG. 1, wherein FIG. 2A is a bottom view of the container, and FIG.
It is a figure which shows the unevenness state near the lower end surface of the leg part along the straight line shown to (a) graphically.

3A and 3B show an uneven state on the bottom side surface of the container shown in FIG. 1, wherein FIG. 3A is a side view of the container bottom and FIG.
It is a figure which shows the uneven | corrugated state of the bottom side surface part between adjacent leg parts along the straight line shown to (a) graphically.

FIGS. 4A and 4B show an uneven state on the bottom side surface of the container shown in FIG. 1, wherein FIG. 4A is a side view of the container bottom and FIG.
It is a figure which shows the uneven | corrugated state of the leg part outer surface part along the straight line shown to (a) graphically.

FIG. 5 is a partial longitudinal sectional view schematically showing a bottom shape of the container shown in FIG. 1 at the time of no filling and at the time of filling.

FIG. 6 shows an example of a conventional plastic container having a petaloid bottom shape, where (a) is a side view and (b)
Is a vertical sectional view of the bottom.

FIG. 7 shows another example of a conventional plastic container having a petaloid bottom shape, wherein (a) is a side view,
(b) is a longitudinal sectional view of the bottom.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure-resistant self-standing container 10 Leg 11 Grounding surface 13 Slope 15 Outer surface 17 Curved surface 18 Bottom side 19 Central curved surface 20 Bottom shape profile when internal pressure is applied 60, 72 Leg of conventional container 70 Conventional container

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-57545 (JP, A) JP-A-56-106740 (JP, A) JP-A-4-44943 (JP, A) 110415 (JP, U) JP-B-59-40693 (JP, B2) JP-B-61-9170 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65D 1/02 B65D 23 / 00

Claims (5)

(57) [Claims] In a pressure-resistant self-standing container having a bottom portion in which a plurality of legs forming a grounding portion are integrally formed at equal intervals in a circumferential direction, an outer portion of a lower end surface of each leg is provided. Has a flat circumferentially wide ground contact surface portion that is in contact with the container support surface when the container is not filled,
On the inner side of the container of the grounding surface portion, a substantially flat inclined surface portion inclined upward toward the inside of the container continuously to the grounding surface portion is formed, and other than the grounding surface portion and the inclined surface portion A pressure-resistant self-standing container characterized in that a plurality of smooth curved surface portions are smoothly connected to a bottom wall. 2. The pressure-resistant self-standing container according to claim 1, wherein the outer side surface of each leg is a smooth convex curved surface that is continuous from the body wall of the container, and the bottom side surface between adjacent legs is the same. The cross section perpendicular to the axis of the container has a smooth concave surface radially inward from the outer surface of the leg, and the cross section along the axis of the container has a smooth curved surface convex downward. A pressure-resistant self-standing container characterized by the following. 3. The pressure-resistant self-supporting container according to claim 1, wherein a lower end surface of the leg portion is wide at an outer portion having the ground contact surface portion, and the width gradually decreases as it goes inward of the container. A pressure-resistant self-standing container characterized by the following. 4. The self-standing pressure-resistant container according to claim 1, wherein an upwardly convex curved surface is formed in a further radially inward portion of the inclined surface portion, and the upwardly convex curved surface is formed. A pressure-resistant self-standing container, characterized in that a central portion at the bottom further inside the portion is a smoothly curved portion that is convex downward. 5. The self-standing pressure-resistant container according to claim 1, wherein an outer side surface of each leg is divergent toward a position higher than a lower end of the leg. Pressure-resistant self-supporting container.