JPH057259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the bottom structure of plastic containers, and more particularly to the bottom structure of plastic containers for storing pressurized liquids such as carbonated beverages.

[Prior art and its problems] Recently, one-way containers have come into widespread use, particularly liquid paper containers and plastic one-way containers. Fields where plastic one-way containers are used in large quantities are:
They are containers for storing non-pressurized liquids such as liquid detergents, edible oils, sake, lactic acid drinks, etc., and are relatively rare in containers for storing pressurized liquids such as carbonated drinks. The reason is that although plastic containers are self-supporting, they are less rigid than glass bottles.
This is because it impairs its shape retention. In particular, when a concave part is formed at the bottom of the container inward, forming a so-called raised bottom, the shape retention of the concave part cannot be maintained and the container bulges out due to the weight of the pressurized liquid. If this happens, the top surface of the stored liquid will drop, giving the container a feeling of wear and tear, and also impairing the stability of the container. Therefore, various proposals have been made to maintain the shape retention of the recessed portion at the bottom of the container.

For example, Japanese Patent Publication No. 48-5708, Japanese Patent Publication No. 51-
In Publication No. 104989 and Special Publication No. 57-57330,
All of these proposals are about the bottom structure of a plastic container for pressurized liquid, and the proposal is that from the recessed part in the center of the bottom,
It has a structure in which a plurality of radially symmetrical hollow ribs are provided toward the collar, which is the bottom outer periphery grounding part.

By the way, in general, when ribs (including hollow ribs) in plastic containers are subjected to bending deformation in a direction perpendicular to the longitudinal direction of the rib, a large resistance force exists in the direction perpendicular to the longitudinal direction of the rib, resulting in poor shape retention. Although effective, if bending deformation is applied along the length of the rib, there is no bending resistance due to the rib.

Therefore, in the bottom structure of any of the plastic containers introduced in the above-mentioned publications, radial hollow ribs are provided symmetrically with respect to the center of the bottom, and there are no hollow ribs between the ribs. Since the ribs are also symmetrical, if bending deformation is applied along a straight line passing through this portion, that is, the radial valley and passing through the center, there is no bending resistance due to the ribs.

Therefore, it is possible to combine a second rib running perpendicular to the longitudinal direction of the hollow radial rib, or
The figures of these publications suggest the provision of step-like uneven portions, or the present inventors have also attempted to do so.

That is, in order to maintain the shape of the recessed part, a radial rib running from the center of the recessed part toward the heel part, which is the bottom outer periphery ground contact part, and a concentric step-shaped second rib are combined in the recessed part. Therefore, it is conceivable to try to prevent deformation due to bending along the longitudinal direction as well as deformation due to bending in a direction perpendicular to the longitudinal direction of the radial rib.

However, plastic bottles containing pressurized liquids may be handled roughly, for example by being dropped from a considerable height onto a hard surface; In this case, bending deformation is not only caused by impact loads in the longitudinal direction of the radial ribs and in the direction perpendicular to the radial ribs, but also bending deformation is caused by complex impact forces in any direction. There was a fear that the structure used lacked reliability regarding the shape retention of the recessed portion.

[Means for solving problems]

Therefore, the present invention was created in an attempt to completely eliminate the conventional problems, and provides a bottom structure that can maintain the shape of the recessed part even if an external force is applied in any direction.

That is, in the present invention, a recessed portion extending toward the inside of the container is formed in the bottom of a cylindrical plastic container formed by blow molding, and a plurality of holes are formed in the recessed portion from the center toward the bottom outer periphery grounding portion. A first rib is formed, the shape of the first rib is spiral so that a straight line passing through the center of the bottom of the container crosses at least one first rib, and each first rib is formed concentrically with the heel part.
The present invention provides a bottom structure characterized in that a second rib is formed by providing a step on the rib.

The configuration of the present invention will be explained in detail with reference to examples.

1, 2, and 3 show an embodiment of the present invention, in which FIG. 1 is a partially cutaway oblique view, FIG. 2 is a side view taken in the direction of the x arrow in FIG. 1, and FIG. Figure 2 A-A
A cross-sectional view showing a cross section and a B-B cross section is shown.

The bottle 1, which is a container made of plastic and molded by blow molding, can store a pressurized liquid, such as a carbonated drink, and has a constricted part (not shown) at the top, and a lid is detachably attached to the top end. is covered with. A recess 3 is provided in the bottom 2 of the bottle 1.
A heel portion 4 is formed on the outer periphery of the recessed portion 3, that is, on the outer periphery grounding portion of the bottom portion 2. A plurality of first ribs 6, 6 are arranged at equal intervals from the center 5 of the recessed part 3 toward the heel part 4, that is, form hollow ribs protruding outward from the bottle 1 through the valley part 7. .

The first rib 6 is formed of a top surface 6a that expands into a fan shape as it approaches the heel portion 4, and left and right side surfaces 6b, 6b for laterally supporting the top surface 6a. The width h of 6b, 6b gradually increases as it approaches the heel portion 4. In other words, the height h of the first rib 6 is greater than the height h of the heel portion 4.
It gradually increases as it approaches .

In addition to this, the top surface 6a of the first rib 6 is
It is formed into a smooth curved shape (spiral shape) toward the heel portion 4, and a plurality of step-shaped second ribs 8 (three steps in the illustration) are provided concentrically with the heel portion 4. Note that although the spiral of the first rib 6 shown in the second figure flows in a clockwise direction, the present invention may also flow in a counterclockwise direction. may be made slightly larger than the thickness of the heel portion 4.

Note that the bottle 1 is not limited to a transparent plastic material, but may be made of an opaque material.

Since the present invention adopts the configuration described above, it has the following effects.

〔Effect of the invention〕

Since the heel part consists of the bottom outer periphery grounding part, the container can sit comfortably, and the shape of the ribs is curved so that a straight line passing through the center crosses at least one of the ribs. Simply put, since it is spiral-shaped, even if bending deformation occurs in any direction, there is always resistance from the ribs, the shape of the recess is maintained, and the recess bulges out to the outside of the container. Does not damage the seating of the container.
Furthermore, if it is molded from a transparent plastic material, the structure of the recessed part at the bottom can give an aesthetic appearance. In addition, since the ribs become larger as they approach the heel, their resistance increases and shape retention is further enhanced.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of an embodiment of the present invention, Fig. 2 is a side view taken in the direction of the x arrow in Fig. 1, and Fig. 3 is a cross-sectional view taken from A to A and B to B in Fig. 2. It is. 1... Bottle, 2... Bottom, 3... Recessed part, 4...
...Heel part, 5... Center part, 6... First rib.

Claims (1)

[Scope of Claims] 1. In a bottom structure in which a recessed part is formed in the bottom of a plastic cylindrical container capable of storing liquid, the recessed part is provided with a heel part consisting of a grounding part on the outer periphery of the bottom from the center part. a plurality of first ribs protruding outward from the container;
A bottom structure of a plastic container, characterized in that the bottom structure of a plastic container is spiral-shaped so as to cross the ribs, and a step is provided in each first rib concentrically with the heel part to form a second rib. 2. The bottom structure of a plastic container according to claim 1, wherein a plurality of first ribs are arranged at equal intervals. 3. A claim in which the top surface constituting the first rib is enlarged in a fan-like shape from the center toward the heel, and the widths of both side surfaces supporting the top are gradually increased from the center toward the heel. Bottom structure of the plastic container according to item 1.