PROCESS FOR THE PRODUCTION OF A COLLAPSIBLE BOTTLE

Abstract: A collapsible or foldable plastic bottle circular bellows like configuration capable of manufacture on current plastic bottle manufacturing equipment with current plastic materials ap­ proved for contact with foods and beverages. The bellows over center and fold to retain the folded condition without external assistance thus providing a self-latching feature. In particular, the bellows of the bottle, when fully folded, cause the bottle to substantially fit within a cup fastened to the base of the bottle. The cup is generally formed by further extending the cup up­ ward and increasing the diameter slightly in comparison with the reinforcing cup on current soda pop bottles.

Description: The present invention relates to a process for the production of a bottle-like collapsible plastic container having a top and a base joined by a substantially cylindrical side wall integral therewith and an aperture in the top, the side wall comprising a plurality of circular bellows formed by conical sections integrally connected by circular fold rings and comprising alternating short portions and long portions, said short portions being in the upright position of the bottle at a greater angle to the bottle axis than said long portions. The bellows of the known containers are produced by blowing a preform within a bottle mold. This blowing results in a more or less gradual decrease of the thickness of the conical sections in relation to the original wall thickness of the preform. The finished articles will therefore be less easily collapsible than the market desires. The invention aims to overcome the above disadvantage of known containers. This object has, according to the invention, been reached by producing the container by suddenly admitting, subsequent to blowing the bottle within a bottle mold, such additional high pressure to the interior of the bottle that at least the inner fold rings obtain a thickness less than that of the conical sections. Description of the drawings Fig. 1 is a partial side cross-sectional view of the collapsible bottle; and Fig. 2 is a partial side cross-sectional view of the collapsible bottle fully collapsed, and Fig. 3 is a top view of the collapsible bottle. Description of the preferred embodiments In fig. 1 the bottle, generally denoted by 10, includes an upper hemispherical portion 12 having a central neck 14 for a cap 16 that may be attached and detached. The bottle 10 is formed with generally bellows-shaped sidewalls 18 and includes a separate bottom cup 20 affixed to the bottom of the bottle 10. The cup 20 side wall 22 is generally smooth to provide a suitable surface for the labels that are affixed to the bottle. Labels may also be affixed to the generally smooth hemispherical portion 12 at the top of the bottle. As illustrated in Fig. 1, the bellows-shaped side wall 18 of the bottle extends down within the cup side wall 22 as illustrated at 24. Typically the bellows extend almost to the bottom of the bottle and cup and the cup side wall extends generally toward the middle of the vertical height of the bottle. Each bellow here indicated by 26 comprises a downwardly and outwardly extending conical portion 28 and a downwardly and inwardly extending conical portion 30 which is substantially smaller and at a much greater angle to the axis of the bottle. In the figure six bellows are shown; however, in actual practice a very large number of bellows, each of which is much smaller in proportion to the size of the bottle, is preferred. Thus, as shown, the bellows are greatly enlarged in proportion to the typical soda bottle in which the bellows are incorporated. Fig. 2 illustrates the bottle substantially collapsed for a volume approximately one-half that of the expanded bottle. Thus, the bottle substantially eliminates the air volume over the liquid beverage down to the point where the bottle is half full. As shown, the individual bellows 26 are collapsed or folded over such that the short portion 30 of each bellow is folded over the long portion 28 of the adjacent bellow. In Fig. 2 as in Fig. 1 the size of each bellow in proportion to the size of the bottle is greatly exaggerated. In actual practice the increase in diameter of the bottle attributed to the bellows is so limited as to not substantially increase the diameter of the bottle with the cup attached. The cup side wall 22 interior diameter need only be sufficient 23 to permit the bellows to fold over and become overcentered as shown in Fig. 2. The flexibility of the cup material assists in permitting the bellows to fold and snap over. Once snapped over as shown in Fig. 2, because of the cylindrical configuration of the bottle and bellows, the bellows will not expand despite the failure to replace the cap 16 on the bottle. The close proximity 21 of the sidewall 22 of the cup also assists in preventing the collapsed bellows from expanding. The cup side wall 22 is substantially smooth to assist in attaching labels and the like to the cup and bottle combination. The cup is adhesively affixed to the bottom of the bottle as shown at 32 in both figures. It is preferred that the bellows be generally shaped as shown to obtain the overcentering action that holds the bottle collapsed. However, even without the overcentering action, the attachment of the cap to the collapsed bottle prevents the bottle from expanding due to the external atmospheric air pressure. It is envisioned that in a vast majority of instances the plastic utilized for the bottle will be a very strong flexible plastic such as acrylonitrile or similar plastic approved by the Food and Drug Administration. In some instances a relatively soft plastic may be utilized for the bottle in which case the overcentering action would not be completely satisfactory and the replacement of the cap on the bottle required to retain the partially full bottle in the collapsed state. To assist in the folding and collapsing of bottles manufactured from stretched plastics such as are typically used currently for the more popular brands of soda pop in two litre bottles, such stretch plastics are typically formed into bottles by first creating an injection molded or blow molded preform having a relatively thick plastic wall and bottom and generally in the shape of a common laboratory test tube. The preform, heated above the heat distortion temperature of the plastic, is then blown in a bottle mold to the full bottle size and wall thickness. In the process of blowing the bottle the side wall of the bottle is stretched, which in combination with the particular plastic adds significantly to the tensile strength of the bottle side wall. After removal from the bottle mold, the bottom cup is adhesively affixed to the bottom of the bottle to reinforce the bottle bottom. Applicant's bottle is manufactured in a similar manner; however, the cup 20 is sized in depth and inside diameter to accomodate the collapsed bellows as shown in Fig. 2. Typically, the cup will be two or more times the depth of the plastic cup on the bottom of a conventional two litre soda pop bottle. In blowing the bottle, subsequent to blowing the bottle within the bottle mold and before removal from the bottle mold, additional high pressure air or nitrogen gas is suddenly admitted to the interior of the bottle to expand the side wall of the bottle into the bellows forming grooves of the mold. The sudden expension with the high pressure air or gas stretches the side wall further at the lesser diameters of the bellows such as 34 thereby forming a stretched circular thin spot or fold ring in the bottle wall. In addition, the conical portions 28 and 30 will be slightly stretched further as blown from the bellowless wall indicated at 36 to the final bellows configuration. The additional thinning of the wall permits the bellows action to more easily take place with the plastic materials currently utilized and the wall thicknesses currently utilized. The additional thinning of the wall beyond that of the conventional uncollapsible bottle is not detrimental to the strength of the bottle because the ribbing effect created by the bellows configuration adds additional rigidity in all directions with the exception of the collapsing direction of the bottle. Thus, the fold rings and thinned sections of the side wall assist in creating an easily collapsible bottle that remains convenient for handling and storing. Fully collapsed into the cup, the bottle remains easy to use and when completely emptied and stored, only takes approximately half the volume of the conventional uncollapsible soda pop bottle. In States such as Michigan, the storage of empty bottles for return to the bottling plants and distributors is a significant problem. Collapsible bottles can significantly assist in lessening the storage volumes required for large quantities of empty bottles in storage rooms before they are returned to the reprocessor of the bottles.

Claims: Process for the production of a bottle-like collapsible plastic container (10) having a top and a base joined by a substantially cylindrical side wall (18) integral therewith and an aperture in the top, the side wall comprising a plurality of circular bellows (26) formed by conical sections integrally connected by circular fold rings and comprising alternating short portions (30) and long portions (28), said short portions being in the upright position of the bottle at a greater angle to the bottle axis than said long portions, characterized in that said container is produced by suddenly admitting, subsequent to blowing the bottle within a bottle mold, such additional high pressure to the interior of the bottle that at least the inner fold rings (34) obtain a thickness less than that of the conical sections.

Inventors: TOUZANI, WILLIAM
Applicants: TOUZANI, WILLIAM
Application year: 1985
Main classification: B65D1
IPC codes: B65D1