GB2044211A - A thin-walled synthetic resin bottle - Google Patents

Abstract

In a thin walled biaxially- orientated synthetic resin bottle having a bottom wall 4 provided with an inwardly projecting frustum-shaped recess 5 and an annular supporting surface 7, radial grooves 8 are provided in the surface 7, having sidewalls 8b, which are preferably vertical, to increase the strength of the bottom wall. The drum or sidewall portion 3 of the bottle curves inwardly to join the bottom wall 4. <IMAGE>

Description

SPECIFICATION Thin-walled synthetic resin bottle The present invention relates to a thin-walled synthetic resin bottle which is suited to be charged with beverages such as carbonated or cooling beverages, and more particularly to a bottle of the above type having a strengthened bottom wall.

Glass bottles have been mostly used as the conventional bottles to be charged with the carbonated beverages or the like. However, glass bottles are so heavy as to increase the cost of transportation and to cause inconvenience in handling.

In order to eliminate the aforementioned drawback, there have been trials in which a synthetic resin bottle made by biaxial orientation is made to have its drum portion formed into a cylindrical shape and its bottom wall protruding outwardly into a hemispherical shape. This is because the bottle can have its strength or other physical properties improved by biaxial orientation even if it is made thin.

Since, however, the bottle has its bottom wall protruding outwardly into a hemi-spherical shape, it cannot be stood stably unless it is provided at its bottom portion with a flared separate stand; resultant drawbacks are that the cost is increased and that the appearance is marred. If, moreover, the bottle is not correctly fitted in the stand such that it is inclined, the liquid injection becomes out of point thereby to cause another drawback in that the charging operation is impaired.

In order to stably stand the bottle, there have also been made other trials, in which a plurality of legs are formed which bulge from the circumferential edge of the bottom wall of the bottle. In this trial case, however, the legs have their lower ends so thinned that they are liable to be broken thereby to fail to acquire sufficient strength at the bottom portion of the bottle.

It is therefore an object of the present invention to provide a synthetic resin bottle which is thin-walled while maintaining sufficient strength at the bottom portion thereof.

Another object of the present invention is to provide a synthetic resin bottle which can be stood stably even if it is empty.

Yet another object of the present invention is to provide a synthetic resin bottle which has its groundable bottom wall surface formed with a number of vertical walls so that the bottom wall can be elastically deformed and enhancing the strength of the bottle.

According to the present invention there is provided a thin-walled synthetic resin bottle formed by biaxial orientation, having a drum portion, and a bottom wall comprising a frustum-shaped recess projecting inwardly of the bottle and an annular supporting surface between the recess and the drum portion, a plurality of radially extending grooves being provided in the annular surface for increasing the strength of the bottom wall.

According to the present invention, there is further provided a thin synthetic resin bottle having at least its wall portion other than the neck portion thereof biaxially oriented, comprising a drum portion having its lower portion curved inwardly to have the most reduced diameter at the lower end portion thereof, and a bottom wall having its centre portion protruding inwardly of said bottle to form a frustum-shaped recess while leaving an annular surface to be grounded thereat between the brim of said recess and the lower end portion of said drum portion, wherein there is provided a plurality of grooves formed substantially equidistantly in a radial shape in said bottom wall so that vertical walls depending vertically from raised walls are formed to increase the strength of said bottom wall.

Other objects and advantages of the present invention will become apparent from the following description of particular embodiments of the invention made with reference to the accompanying drawings, in which: Figure 1 is a partially cut-away sectional view showing a thin-walled bottle according to a first embodiment of the present invention; Figure 2 is a bottom view showing the bottle of Figure 1; Figure 3 is similar to Figure 1 but shows a thin-walled bottle according to a second embodiment; Figure 4 is similar to Figure 2 but shows the bottle of Figure 3; and Figure 5 is a sectional view showing a lower portion of a bottle, being a modification of the second embodiment, in which the groundable surface of the bottle bottom is limited to the outer circumference thereof.

A bottle according to a first embodiment of the present invention will now be described with reference to Figures 1 and 2. The bottle of synthetic resin, as indicated generally at numeral 1, is produced by injection-moulding a parison of synthetic resin, and the parison is subjected to blow moulding for biaxial orientation. A saturated polyester resin is desired as the synthetic resin material for the bottle, but a synthetic resin such as polypropylene or polyviny Bichloride may also be used. The bottle 1 has a neck portion 2 which is transferred as it is from the neck portion of the parison without any biaxial orientation. On the other hand, the drum portion 3 and bottom wall 4 of the thin bottle 1 extending downwardly from the neck portion 2 are biaxially oriented to have enlarged diameters.

The drum portion 3 has a circular cross section transverse to its longitudinal axis and has a lower portion distal of the neck curved inwardly to have a minimum diameter at the end thereof adjacent the bottom wall. The bottom wall 4 has its centre portion protruding inwardly of the bottle to form a frustumshaped recess or kick 5, which is not so high as the total height of the bottle. Frustum-shaped recess 5 has a circumferential wall 6.

Between the lower end portion of the circumferential wall of the drum portion 3 and the brim of the circumferential wall 6 of the frustum-shaped recess 5, there is formed an annular surface 7, on which the bottle maybe supported. The annular surface 7 is formed with a plurality of grooves 8 which are arranged equidistantly to extend in radially of the bottle bottom, and inwardly of the bottle. Each of the grooves 8 has a raised inward horizontal wall 8a positioned at about midway between the level of the bottom of the frustum-shaped recess 5, and the annular surface 7. From both sides of the raised wall 8a of each groove 8, there are formed a pair of vertical walls 8b which vertically depend so that when the bottle is dropped the shock can be absorbed by the elasticity of the vertical walls 8b.

A plurality of radial ribs having a thickened section may be formed in the annular surface 7 of the bottle bottom so that the bottom is further reinforced.

According to the present invention having the construction thus far described, since the grooves 8 are formed equidistantly and radially in the annular surface of the bottle bottom, many vertical walls are formed by the respective grooves so that the falling strength of the bottle can be enhanced. Since, moreover, the vertical walls can be elastically deformed to have the shock absorbing effects, the bottle can be stood without any damage upon a floor or the like. Still, moreover, since the raised walls 8a are midway between the bottom ofthefrustum- shaped recess 5 and the annular surface 7, the effective capacity of the bottle is not especially reduced.Since it is sufficient that not only the depth of the grooves 8 but also the height of the frustumshaped recess 5 can be restricted within a small range, the thickness of the bottle bottom can be prevented from becoming excessively small so that the strength of the bottle can be enhanced, particularly having regard to being dropped.

Since the drum portion of the bottle is partly formed into a cylindrical shape and partly curved inwardly at its lower portion, the bottle according to the present invention can withstand internal pressure even if it is used as a container for storing beverages under high pressures. Since, moreover, the bottle bottom has its centre portion protruding inwardly of the bottle to form a frustum-shaped recess, the bottle is grounded only at the annular surface 7 of the outer circumference so that it can be stably stood under the condition in which it is evacuated or filled up with a liquid. If the internal pressure of the bottle is increased, the bottom of the recess 5 is lowered owing to its elasticity, thereby to increase the capacity of the bottle so that the internal pressure is accordingly reduced hence increasing the pressure-resisting strength of the bottle as whole.In this instance, the standing position of the bottle can remain stable because no influence is exerted upon the grounded surface even if the frustum-shaped recess 5 is expanded or deformed.

Another or second embodiment of the present invention will now be described with reference to Figures 3 and 4. This second embodiment is similar to the first embodiment in that the drum portion 3 of the bottle has its lower portion curved inwardly and that the bottom wall 4 is formed with the frustumshaped recess 5 which protrudes inwardly. The annular surface 7 acting as the supporting surface is also formed between the brim of the circumferential wall 6 of the frustum-shaped recess 5 and the lower end portion of the drum portion 3. In the second embodiment, it should be noted that the radial width of the annular surface 7 is made larger than that of the first embodiment.It should also be noted that the grooves 8 are formed in the annular surface 7 and extend radially of the bottom wall 4 and that the raised walls 8a forming the horizontal bottoms of the grooves 8 are positioned substantially at the same level as the bottom of the frustum-shaped recess 5.

In this way, the second embodiment is made different from the first one in that the height or level of the raised walls are increased. In other words, the depth of the grooves 8 is made larger than that of the first embodiment.

According to the second embodiment having the construction thus far described, since the grooves 8 are made deeper than those of the first embodiment so that their vertical walls are made to have a greater height, the internal pressure of the bottle to be born on the frustum-shaped portion 5 can be dissipated and absorbed by the aforementioned vertical walls 8b. As a result, it is possible to prevent the frustumshaped recess 5 from being locally deformed to decrease the strength of the bottle and the groundable surface of the bottle bottom from being deformed so as to make the standing position of the bottle unstable.

Since, moreover, the height of the vertical walls 8b and the width of annular surface 7 are made larger than those of the first embodiment, the falling strength of the bottle can be further improved.

Now, with reference to Figure 5, a modification of the second embodiment will be described, in which the contour of the lower portion of the bottle is slightly changed. According to this modification, the drum portion 3 of the bottle has its centre portion reduced at its lower end to have a tapering portion 3a while leaving the remaining portion curved inwardly in a similar manner to the second embodiment. The bottom wall 4 has its centre portion formed into a frustum-shaped recess 5. It should be noted here that the outer circumference of the annular surface 7 is lower than the inner circumference so that only the former is grounded to provide a radially expanded groundable surface.

According to the modification, therefore, the bottle is stood only at the outer circumference of its bottom so that its standing position is further stabilized. This stabilization can be further improved by the radial expansion of the annular surface. This is because the bottle drum portion has its lower portion extending into the tapering portion from the curved portion.

Claims (7)

1. A thin-walled synthetic resin bottle formed by biaxial orientation, having a drum portion, and a bottom wall comprising a frustum-shaped recess projecting inwardly of the bottle and an annular supporting surface between the recess and the drum portion, a plurality of radially extending grooves being provided in the annular surface for increasing the strength of the bottom wall.

2. A bottle as claimed in Claim 1, wherein the depth of each groove is approximately equal to half the depth of the recess.

3. A bottle as claimed in Claim 1, wherein the depth of each groove is approximately equal to the depth of the recess.

4. A bottle as claimed in Claim 1,2 or 3, wherein sidewalls of the grooves are parallel to or contained in planes containing the axis of the bottle.

5. A bottle as claimed in any of Claims 1 to 4, wherein the lower portion of the drum portion adjacent the bottom wall curves inwardly of the bottle when viewed in longitudinal cross section, such that the transverse diameter is a minimum where the drum portion meets the bottom wall.

6. A bottle as claimed in Claim 5, wherein the curved portion of the drum portion ends in a downwardly convergent frusto-cone.

7. Athin-walled synthetic resin bottle substantially as hereinbefore described with reference to Figures 1 and 2, or 3 and 4, or 5 of the accompanying drawings.