US3843025A - Method of preparing plastic containers - Google Patents

Abstract

A method is taught for blow-molding a bottle or other container having an integral fluid transfer passage. A preformed member incorporating the passage is inserted in a mold and the parison is blown into contact therewith. The member is designed so that the parison will bridge the inlet opening, stretch into the opening and finally burst under the blowing pressure, thereby opening up communication between the interior of the container and the exterior environment.

Description

United States Patent [191 Holt ' [451 Oct. 22, 1974 METHOD OF PREPARING PLASTIC CONTAINERS Inventor: William G. Holt, Raynham, Mass.

Hercules Incorporated, Wilmington, Del.

Filed: June 22, 1973 Appl. No.: 372,576

Assignee:

US. Cl. 222/207, 222/383 Int. Cl B65d 35/10 Field of Search 222/207, 209, 383, 211

References Cited UNITED STATES PATENTS 3,648,902 3/1972 Humphrey 222/207 3,726,442 4/1973 Davidson et al. 222/207 Primary Examiner--Robert B. Reeves Assistant Examiner-Thomas E. Kocovsky Attorney, Agent, or Firm-William S. Alexander [57] ABSTRACT 3 Claims, 9 Drawing Figures PAIiminumzzraz a SHEUIN 4 ll-III l1 FIG. 2

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1 METHOD OF PREPARING PLASTIC CONTAINERS This invention relates to the art of preparing plastic containers incorporating means for effecting communication between the interior and exterior thereof through their wall. In a specific embodiment it relates to a method of blow-molding a bottle incorporating a pump assembly including a channel for conducting a liquid from the interior of the bottle through the wall.

There are many occasions when it is desirable to provide a means of communication between the interior of a container and the external environment and a substantial body of art has grown up exemplifying approaches to accomplish this end. One important area where there is a use for this type of structure is in incorporating a pump assembly into a plastic bottle. US. Pat. No. 3,575,949 is illustrative of a good method of accomplishing this purpose and also of the shortcomings of the best technique known to date. The reference patent deals specifically with incorporating a pump into a bottle. Since this is an important area in which the invention has considerable use, the invention will be de scribed in detail with respect to a specific embodiment of this application. However, the invention is not so limited as will hereinafter be made apparent.

In the method disclosed in the reference patent, an elongated channel defining element is placed in a mold and a parison is blow-molded into contact with the channel defining element. A problem encountered with the technique as taught in the reference is that the container wall covers the inlet to the channel defining element, thereby blocking communication between the channel and the interior of the container. It then becomes necessary to introduce a needle or other puncturing device through the container wall and into the channel, opening up communication between the channel and the interior of the container, then rescaling the puncture on the outside of the channel. This method is less than satisfactory as it involves extra handling and also leaves a point of potential weakness on the wall of the container. 1

It is the object of this invention to eliminate these shortcomings by effecting communication between the exterior and the interior of the container during the blow-molding step.

Other objects of this invention will become apparent from the following description with reference to the drawing wherein:

FIGS. 1 and 2 are exploded perspective views of a pump assembly to be employed in carrying out the instant invention.

FIG. 3 is a view of a mold having the pump assembly of FIG. 1 and a parison therein, preparatory to forming a bottle.

FIG. 4 is a view of a blow-molded bottle incorporating the pump assembly of FIGS. 1 and 2.

FIG. 5 is a view taken along section line 5-5 of FIG. 4.

FIG. 6 is a view along section line 6-6 of FIG. 4 showing the inlet channel as incorporated into a bottle.

FIGS. 7, 8 and 9 depict other structures in which the principles of this invention are employed.

Referring to FIGS. 1 and 2, there are illustrated inner and outer exploded views respectively of a pump assembly 10 comprising a preformed channel defining and support member 12, a flexible valve 14 and a shroud 16. The channel defining member includes an elongated wall 11 and a fiat valve support table 18. Projections 13 and 13' joined at their upper extremity by an arcuate portion 21, extend inwardly from the inner surface of the elongated wall 11 todefine a channel 15 communicating with the outersurface of valve support table 18 via opening 20 (FIG. 1) The lower end of channel 15 has an enlarged portion 22 which will be more fully explained hereinafter. At the upper end of valve support table 18 there is an: elongated nozzle pin 26, and an inner and outer sealing lip, 17 and 19 respectively, projecting from thesurface of table 18.

The flexible valve member 14 includes an annular peripheral 0" ring 28 which surrounds and encloses an inner annular ring 30, the two rings being separated by an annular groove 31. The inner annular ring 30 has a greater height than the peripheral annular 0" ring 28 and at its outer extremity it supports valve face plate 32 which, in turn, supports a bubble 33. Disposed transversely across the inner annular ring 30 and extending very slightly above the inner extremity thereof are two vane portions 34 and 35. Collectively, elements 30, 32, 33, 34'and 35 form three chambers 36, 37 and 38 on the inner surface of member 14. At the top of chamber 38 is a poppet 39, containing discharge opening 48. On the outer surface, the poppet 39 is encircled by sealing ring 23. g

The shroud 16 comprises a flat section 40 having an opening 42 adapted to receive bubble 33 and a hollow tubular nozzle 44 extending outwardly from the outer surface thereof, and terminating in discharge opening 45. The top part 41 of flat section 40 is undercut slightly to receive sealing ring 23 and contains an opening 43 extending through nozzle 44 to the end thereof where it is reduced to the size of discharge opening 45. Opening 43 is slightly larger than nozzle pin 26. Flat section 40 is surrounded by an annular raised shoulder 46 and a peripheral annular lip 47.

When elements 12, 14 and 16 are assembled, valve 14 is lined up on valve support table 18 so that chamber 36 is in communication with channel 15 via opening 20 and nozzle pin 26 is inserted in discharge opening 48 and inner sealing ring 17 on table 18 fits into annular groove 31. Shroud 16 is placed over the valve 14 with opening 42 fitting over bubble 33 and nozzle pin 26 fitting into opening 43 in nozzle 44. On the inner surface of the shroud 16, flat surface 32 of the valve rests against flat section 40 and sealing ring 23 fits into the undercut top section 41.

With reference to FIG. 3, to incorporate the pump into a bottle, the assembled pump 10 is integrally united with a blow-molded bottle during the manufacture thereof. The bottle is blow-molded by extruding a parison 50, clamping a pair of mold halves 52 and 54 about the parison and expanding the parison to fill the mold in a manner well known to the art. The assembled pump 10 is incorporated with the bottle during the blow-molding operation by inserting the pump 10 into a corresponding cavity in the mold half 54 prior to closing the mold upon the parison.

As it is expanded to fill the mold, the parison bridges over the side walls 13 and 13 and seals against the inside surface of the elongated wall 11 of member 12 to enclose channel 15 as shown in FIG. 5 and FIG. 6, and also seals against the surface of plate portion 18 of member 12. The enlarged end 22 of the channel has an arched edge wall 24 which, with the inner surface of wall 11, defines an inlet opening 25 to the channel 15.

The circumference angle and height of the arched edge wall 24 are so proportioned that when the parison engages and seals against it under blowing pressure, the parison will stretch and enter the opening 25 of the inlet channel formed by the arched wall 24 and f1- nally rupture, thereby communicating the interior of the bottle with the channel 15.

When incorporated into a bottle, the pump operates, in principle, as described in US. Pat-No. 3,575,949.

In carrying out the process of the invention as described in the preceding paragraph, there is an important interrelationship of the dimensions of the inlet opening, the plastic being molded, and the temperature and pressure at which the molding is being carried out. Since there is, for a selected polymer, a fairly welldefined set of temperature and pressure conditions under which blow-molding is optimally carried out, the parameter most readily varied and thus the most critical is the dimension of the inlet opening. If the peripheral dimension of the inlet opening is too small, the portion of the parison bridging the opening will not stretch. This is illustrated in the embodiment of the pump depicted herein wherein the parison 50 bridges the walls 13 and 13' of the channel 15 without stretching. The depth of the opening relative to its peripheral dimension is also important since enough length must be provided to allow the parison to stretch into the cavity and rupture prior to engaging the rear of the cavity. If the peripheral dimension of the opening is too large, then the parison will either drape into the cavity behind the edge of the opening and engage the wall behind without rupturing rather than stretching and rupturing, or it will simply continue to stretch without reaching its elastic limit and not rupture. To the extent that temperature can be varied within the inherent blow-molding limits for the polymer being used, it is important that the temperature be above the temperature at which the amount of molecular orientation which takes place is enough to prevent rupture of the material bridging the opening and below that at which plastic flow takes place so readily that the polymer sags into the opening without stretching or at which, in the case of the embodiment depicted in the drawings, it sags into the channel between walls 13 and 13 and creates a blockage therein. This condition, for purposes of this description, is referred to as involuntary plastic flow. Pressure, aside from the inherent requirement for the plastic, is important in that it must be sufficient to compress any air entrapped behind the stretching portion of the parison sufficiently to allow the necessary stretching and breaking. lt will be apparent that optimum conditions can readily be determined empirically for any specific structure being prepared.

Employing the principles described hereinabove with respect to the bottle pump, it is possible to form other structures having communication between their interior and the exterior environment without the necessity of drilling holes and welding the communicating members after the container is formed. FIG. 7 depicts in cutaway a blow-molded container having a breather tube 62 integrally molded therewith so that its contents can be poured smoothly. FIG. 8 depicts a squeeze bottle 65 having a suitably bent discharge tube 66 integrally molded therewith. FlG. 9 depicts a blow-molded container such as, e.g., a carboy, having a valve assembly 72 and a pouring spout 74 integrally molded therewith.

Each of the structures depicted in FIGS. 7, 8 and 9 is fabricated using the same techniques and the same process considerations as are required in forming the bottle described previously. That is to say, a previously prepared channel defining member is inserted into a mold and the container is blow-molded into contact therewith. In each case the insert can, and preferably will, have an exterior flat surface analogous to the channel support member 12 of the bottle described hereinabove which becomes a part of the exterior container wall as does the channel support member 12. In any of these embodiments, the same considerations relating to the size of the opening as it relates to the temperature, pressure and polymer identity apply. For any structure desired, these interrelationships can readily be determined empirically.

What I claim and desire to protect by Letters Patent l. A blow molded thermoplastic container comprising integral bottom, top and side walls, and an elongated fluid transfer member embedded in a vertical position in a side wall, said member including an elongated vertical flat portion having a pair of substantially parallel elongated ridges projecting therefrom toward said side wall, said ridges being spaced apart and positioned in abutting relationship to said side wall to form an enclosed vertical passageway, the top of said passageway being in communication with the exterior environment, the bottoms of each ridge being enlarged and flared inwardly toward the side wall and having an arched portion interconnecting the ridges to define an enlarged tapered inlet chamber, the side wall of said container extending at least partially into the inlet chamber and having an opening therein whereby the interior of the container is in communication with the vertical passageway.

2. A container as recited in claim 1 wherein the fluid transfer passage is an elongated channel extending to substantially the bottom of the container and having its inlet opening located at its lower extremity.

3. A container as recited in claim 2 including a manually operated pumping means adapted to remove fluid from the container via the fluid transfer passage.

Claims (3)

1. A blow molded thermoplastic container comprising integral bottom, top and side walls, and an elongated fluid transfer member embedded in a vertical position in a side wall, said member including an elongated vertical flat portion having a pair of substantially parallel elongated ridges projecting therefrom toward said side wall, said ridges being spaced apart and positioned in abutting relationship to said side wall to form an enclosed vertical passageway, the top of said passageway being in communication with the exterior environment, the bottoms of each ridge being enlarged and flared inwardly toward the side wall and having an arched portion interconnecting the ridges to define an enlarged tapered inlet chamber, the side wall of said container extending at least partially into the inlet chamber and having an opening therein whereby the interior of the container is in communication with the vertical passageway.

2. A container as recited in claim 1 wherein the fluid transfer passage is an elongated channel extending to substantially the bottom of the container and having its inlet opening located at its lower extremity.

3. A container as recited in claim 2 including a manually operated pumping means adapted to remove fluid from the container via the fluid transfer passage.

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