US3548564A - Process for fabricating a pressurized container - Google Patents

Description

' J. K- BRUCE ETAL Dec. 22, 1970 PROCESS FOR FABRICATING A PRESSURIZED CONTAINER Original Filed May 10, 1966 4 Sheets-Sheet 1 WW m m H Dec. 22, 1970' J. K. BRUCE ET AL PROCESS FOR FABRICATING A PRESSURIZED CONTAINER 4 Sheets-Sheet 2 Original Filed May 10, 1966 ,fMl/M ATTORNEY Dec. 22, 1970 Original Filed May 10. 1966 J. K- BRUCE ETAL PROCESS FOR FABRICATING A PRESSURIZED CONTAINER 4 Sheets-Sheet 5 Ill INVENTORS.

ATTORNEY Dec. 22, 1970 J. K. BRUCE ET AL PROCESS FOR FABRICATING A PRESSURIZED CONTAINER Original Filed May 10, 1966 5'54/1 1/4/6 MP 35 mm 800) /2 706577/5? 70 AKA/EVA- 65AM 2a 9 /0 w/z/ //r/ FAQ/PE 4 Sheets-Sheet 4.

United States Patent Office 3,548,564 PROCESS FOR FABRICATING A PRESSURIZED CONTAINER John K. Bruce and Theodore R. Bruce, Burbank, Calif., assignors to Sterigard Company, Burbank, Calif., a California limited partnership Original application May 10, 1966, Ser. No. 548,963, now Patent No. 3,393,842. Divided and this application Mar. 1, 1968, Ser. No. 709,682

Int. Cl. B65b 3/10 US. Cl. 53-36 5 Claims ABSTRACT OF THE DISCLOSURE The open end of a flexible, elastic bag is stretched over the open end of a cylindrical body such that a portion of the bag is in tensioned contact with a portion of the cylindrical outside surface of the body. The sealed end of the bag is inserted in the body proximate the latters bottom. A cover or cap is double-seamed onto the open end of the body to effect a pressure-tight seal between the bag, the cap and the body. The body and bag are respectively charged with propellant and product and a dispensing valve mounted on the cap.

CROSS REFERENCE TO RELATED APPLICATIONS This is a divisional application of US. application Ser. No. 548,963, filed May 10, 1966, now Pat. No. 3,393,842.

BACKGROUND OF THE INVENTION The present invention relates to pressurized containers in general and, in particular, to a process for fabricating a pressurized dispenser having a product-containing bag.

Products are often marketed in self-dispensing containers commonly referred to as Aerosol containers or bombs. These containers are rigid cylindrical cans filled with a mixture of the product to be dispensed and a propellant. The container is provided with a finger-actuated valve which, when operated, dispenses a mixture of the product and the propellant. The pressure of the propellant provides the dispensing force.

Such dispensers are only useful where propellant is readily miscible with the product. The propellant and product are always combined which results in a change of product characteristics and performance. In the dispensing of most items it is difiicult to combine the product and propellant and retain required product characteristics. In food products the required texture and flavor cannot be produced. Catsup, for example, becomes a pink foam. Moreover, many products are not suitable for pressurized dispensing because of chemical interaction between the product and the propellant or the product and its metal container.

To overcome the problems inherent with a propellant and a product in the same chamber, several concepts have been proposed to separate the product and the propellant. One such concept envisions a piston between a product and propellant chamber. The chamber volume occupied by the piston is considerable, often reaching 50 percent of the total container volume. In addition to the cost of providing a piston and the waste space, the container must be of an expensive extruded type to present a smooth and continuous wall for the piston. This is necessary to provide relatively free piston movement and a sealing surface to reduce excessive product seepage into the propellant. Because of the required fit between the piston and wall, any dents in the container wall render the dispensing device inoperative. Moreover, a high pressure propellant is necessary with this type of container because of piston friction. High pressure propellants in- 3,548,564 Patented Dec. 22, 1970 crease the hazard of explosion and the amount of propellant required. In addition, only highly Viscous products may be used with this type dispenser because the product is required to seal the product chamber from the propellant chamber.

Other concepts in pressurized dispensers include diaphragm and sack type dispensers. These have not been accepted because of substantial problems in manufacture, diflic'ulties in operation and excessive cost.

In summary, it is highly desirable to separate the propellant from the product. Separation should be accomplished with a minimum expenditure of space for the separating means. Moreover, it is highly desirable to provide a pressurized container having a large volume devoted to product space and a relatively small volume devoted to propellant. These requirements should be met with a minimum of manufacturing costs.

SUMMARY OF THE INVENTION The present invention provides a method for fabricating a pressurized fluid-dispensing container with separate propellant and product chambers. The method includes the step of attaching a flexible, elastic bag to a containers body in a reliable, simple and effective manner. The flexible, elastic bag provides product and propellant separation.

In general, the method contemplates affixing a flexible, elastic bag onto the open end of a rigid, hollow and cylindrical body such that the open end of the bag extends over an open end of the body with a portion of the bag in tensioned contact with the outside, cylindrical surface of the body. The bag has a sealed end which is inserted into the bodys interior. A cap is placed on the open end of the body and seamed in place such that a pressure tight seal is formed between the bag, the cap and the body.

Preferably, the outside diameter of the body is greater than the expanded diameter of the bag and the bag is line-sealed as by a heat seal at one end. The interior circumference of the body is slightly larger than the exterior perimeter of the bag. When the perimeter of the bag is slightly smaller than the interior circumference of the body, the sealed end of the bag within the body takes an arched configuration. The apex of the arch lies at the longitudinal axis of the container. The sides of the arch extend downwardly from the apex towards the bottom of the container. The interior volume of the body outside the bag and bounded by the arch becomes a propellant chamber. The propellant chamber is thus somewhat wedge-shaped allowing a propellant injection needle to pass into the chamber without rupturing the bag. The interior of the bag proximate its sealed end is saddleshaped because of the arch. Additional product volume between the interior surfaces of the archs walls and the proximate lateral surfaces of the bag is therefore available.

The seam between the cover or cap and the body is preferably formed by interlocking the two with a reverse bend of the open end of the body and a double reverse bend of the edge of the cap. The open end of the bag is sandwiched in the seam between the cap and the body for the full extent of the seam with a portion of the open end of the bag still in direct tensioned contact with the smooth cylindrical portion of the outside surface of the body. This type of seam may be effected by providing an externally extending radial flange at the open end of the body and a cap with a downwardly extending flange connected through a horizontal portion and a U-shaped annular channel to the balance of the cap. The caps annular flange is bent such that a portion of its downwardly extending portion tucks in and behind a downwardly extending portion of the bodys flange formed at the same time. A portion of the caps flange will then lie against the bag on the outside, cylindrical surface of the body. The exterior, radial surface of the U-shaped channel is disposed in intimate contact with the bag on the inside of the body proximate its opening.

After the bag is affixed, the interior of the body on one side of the bag may be charged with the fluid to be dispensed and the interior of the body on the other side of the bag charged with propellant. A dispensing valve may also be mounted, after the fluid product is charged but before propellant charging, in fluid communication with the product.

The pressurized dispenser of the present invention provides a product dispenser which has separate product and propellant chambers. Therefore, the problems of product-propellant compatibility, product characteristics and product performance are avoided. The bulk of the product chamber may be defined by the interior side walls of the bag and therefore container-product compatibility is not a problem. Because the product is contained in a bag, the concern with product-propellant sealing experienced with pistons is overcome. Moreover, standard container bodies having side seams may be used without affecting the operation and reliability of the dispenser. This means that standard, economical production facilities are readily adaptable to fabricate the dispenser of the present invention.

The arched configuration of the bottom of the bag provides a wedge-shaped propellant chamber that maxi- U mizes the amount of product which can be placed in a given size dispenser. The apex of the arch provides room for the passage of a propellant injection needle. The bag, however, extends downwardly from its apex to provide additional product volume. The arched configuration of the bag provides another salutory feature. This feature resides in the collapsing of the bag as product is withdrawn from the dispenser. It has been found that with the arched type configuration islanding of product is avoided. Islanding refers to the trapping of product by the collapsing bag into pockets which are out of communication with the dispensing valve. Another advantage attendant with the arched configuration of the present invention resides in its reliability. Typically, bags are formed of extruded plastic tubing closed at one end by a heat seal. If the closed bottom of the bag were formed by a separate piece such as a disc, leakage would become a problem because of difficulty in the sealing operation and the length of the seal.

In addition, it has been found that a much smaller amount of propellant is needed with this dispenser because none of the propellant is exhausted through the dispensing valve as the product is dispensed. Thus the container will hold more product and less propellant. It has also been found that only a small amount of propellant pressure is needed to obtain satisfactory discharge of the product. This pressure, which may be in the neighborhood of to p.s.i., means there can be a reduction in the strength requirements of the container which makes possible the use of less expensive containers. The danger of container explosion by inadvertent exposure to heat is also reduced because of the low pressure.

In its preferred form, the present invention joins the cover or cap with the body through a double seam with a portion of the open end of the elastic bag sandwiched in the seam. The double seam insures a completely secure, leak-tight seal between the cap and the body. A true double seaming operation is possible by virtue of the fact that the elastic tubing assumes a skin-like gripping contact with the rigid body to resist tearing, gathering, doubling or twisting as the seaming apparatus proceeds around the perimeter of the container. Any separation or tearing of bag material during seaming is localized because of the large seamed area, thereby avoiding the loss of the seal. Moreover, the tensioned contact of the bag over the top and down the external side wall of the body prevents the bag from being twisted or skewed while seaming.

These and other features, aspects and advantages of the present invention will become more apparent from the following description, appended claims and drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is an exploded view, partly in half section, of a preferred form of the container fabricated by the process of the present invention;

FIG. 2 is an enlarged fragmentary view of the area indicated by line 22 of FIG. 1;

FIG. 3 is a view of the container of FIG. 1, partly in half section, in its assembled state;

FIG. 4 is an enlarged fragmentary view of the area bounded by line 44 of FIG. 3;

FIG. 5 depicts the bag used in the process of the present invention before it is inserted in the container;

FIG. 6 is a perspective view of the bag as it appears when expanded;

FIG. 7 is a perspective view of the bag of FIG. 6 taken from its opposite end and, in addition, attached in the container; and

FIG. 8 is a diagrammatic depiction of the process of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 3 depict a pressurized fluid dispenser 10. The dispenser includes a body portion 12, a top portion 14, a bottom portion 16 and a flexible, elastic bag 18. When assembled, the top and bottom portions are doubleseamed to body portion 12, as indicated respectively by reference numerals 20 and 22 in FIG. 3.

Before assembly, body portion 12 has a radially extending, annular flange 24 at its top and a similar flange 26 at its bottom. Body portion 12 is cylindrical, except for these flanges or lips, and is open at both ends. It is of rigid construction and hollow throughout.

Referring briefly to FIG. 5, bag 18 is depicted before its insertion into body 12. The bag is formed of commercially available plastic tubing stock. The bag has a sealed end 28 and an open end 30. The seal at end 28 is effected by a heat seal. The bag is thin-walled and may be formed of such plastics as polyethylene.

Initially, open end 30 of bag 18 is stretched over the outside surface of body .12 such that a portion 32 extends annularly about and in tensioned contact with the smooth cylindrical portion of body 12 proximate its top. As such, the bag completely encompasses flange 24 as it passes from portion 32 into the interior of body 12. The outer perimeter of bag 18 is slightly less than the interior circumference of body 12. This fact, in conjunction with the line seal at end 28, produces an arched configuration at 34 at the bottom of the bag. The apex of the arch, indicated by reference numeral 36, extends laterally across seal 28. The expanded posture of the bag is best seen in FIGS. 6 and 7.

Top portion 14 of dispenser 10 includes a generally dome-shaped cap or cover 38, a valve cup and a dispensing valve 42. Dispensing valve 42 has a stem 44. A product passage 46 through stem 44 communicates the interior of the dispenser with its outside when the valve is actuated. Communication is effected through a plurality of radial ports 48 at the lower end of stem 44. A valve extension 50 is aflixed at the lower end of stem 44. This valve extension has a sealing surface 52 to prevent product discharge when the dispenser is not in use. A rubber sealing and mounting member 54 is carried by valve cup 40 and in turn carries stem 44 and valve extension 50. The lower end of this member cooperates with sealing surface 52 to prevent product discharge. The upper end of member 54 is held in slight compression by an annular flange 55 on stem 44. A head 56 is disposed annularly about a dispensing valve opening 58 in cover 38. Valve cup 40' has a flange 60- which is crimped to bead '56 and when the dispenser is assembled.

Cover 38 has an external flange 62 which is connected to the balance of the capthrough a U-shaped channel portion 64. Flange 62 includes an annular horizontal portion 66 and a downwardly extending portion 68. In conjunction with channel 64, flange 62 defines an inverted U-shaped channel before assembly.

Bottom portion .16 includes a dish-shaped member 70 which has its convex side facing the interior of body 12. A self-sealing propellant injection valve 72 is affixed on the interior upper surface of dish-shaped member 70. The self-sealing valve admits to the passage of a gassing or pressurizing needle into the interior of the body to charge the space outside bag 18 with a propellant. The valve seals itself upon the withdrawal of the charging needle. The arch configuration at the bottom of bag 18 prevents the bag from being ruptured or pierced by the needle.

As was previously mentioned, bag 18 is of a thin-walled material such as polyethylene tubing having wall thickness of, for example, 0.002 inch. This type of tubing results in a bag which undergoes very little expansion during the product filling operation. Thus an accurate measure of product results. The tubing is prepared prior to its attachment to the container. Typically a predetermined length of tubing is cut from a roll of commercially available rolled tubing. The tubing is heat-sealed to define end 28 either before or after it is cut from the roll. Printed indicia may be placed on the tubing stock if desired.

The physical characteristics of the bag are important. The material should have good memory characteristics for its contraction into intimate contact with the outer wall of the body portion and the encompassed flange. This avoids bunching which affects the seal in seam 20. The material must have a relatively'high hardness to avoid squeezing or thinning during seaming and, therefore, separation. The bag material should accept a heat seal and have good barrier characteristics to avoid product-propellant communication. When filled with product, the bag should not expand; that is, the bag should have good filling resistance. The material should admit to extrusion to avoid a longitudinal heat seal. In addition, the material should be able to withstand relatively high product filling temperatures while not exhibiting brittleness from the low temperature effects of propellant charging.

The tubings open end, indicated in general by reference numeral 30, is expanded and slipped over the top end of body 12 and then released. The tubing contracts inwardly into intimate contact with the cylindrical outer surface of the body. After attachment, the open end of the tubing is therefore stretched over the mouth of body portion 12 and completely encompasses flange 24. The resulting skin-like, elastic contact between the expanded portion of the bag and the exterior portions of the body and its upper flange holds the bag firmly in place during the seaming operation. This prevents the bag from twisting, skewing or being pushed back into the container when top portion 14 is installed. In addition, this tensioned contact prevents gathering or doubling in the seaming operation to be described. Moreover, the contact effects a seal between the bags interior and exterior even before the seaming operation is undertaken.

The assembly operation will now be described with particular reference to FIGS. 1 and 3. After the product-containing bag 18 has been formed and inserted over flange 24 and down the exterior side wall of body 12 as previously described, the remaining portions of the bag are drawn into the interior of the body. This may be accomplished by low vacuum acting through the bottom end of the body.

Top portion 14 is now seamed to the top of body portion 12 and seam 20 formed in the process. The seaming operation bends flange -62 of cover 38 from its FIG. 2 configuration to the FIG. 4 configuration. The flange thus bends upon itself to effect a double reverse bend with a portion of the flange bearing against the exterior portion 32 of bag 18. This may be done by bending horizontal portion 66 at right angles while bending downwardly depending portion 68 at right angles. The seaming operation deforms flange 24 of body 12 such that a portion of its extends longitudinally downward as shown by reference numeral 74 of FIG. 4. The seaming process seals open end 30 of flexible bag 18 between flange 62 of top 38 and flange 24 of body 12 for their entire circumferential extent. As such, the affixed end of the bag extends from the interior of the body into seam 20 where it doubles back on itself and then down the outside of the body. The seaming operation can, if desired, sever that portion of bag 18 which extends below the lower edge of the completed flange.

With self-sealing valve 72 in place, dish-shaped member 70 is seamed to the bottom of body portion 12 and seam 22 fabricated in a manner similar to that of seam 20.

The product is then charged into the interior of body 12 through opening 58 in cover 38. Valve 42, attached in valve cup 40, is then mounted by crimping flange 60 about bead 56 at a plurality of locations. Opening 58 is covered by the latter operation. Propellant is then charged through valve 72 into the propellant chamber above bottom portion 16 and below arched portion 34 of bag 18. To this end, a gassing needle is positioned beneath the dispenser and caused to pass through the self-sealing valve to introduce any one of a number of commonly used propellants. One such propellant is octafluorocyclobutane (commonly referred to as food grade C-318 Freon).

Dispensing the product contained within dispenser 10 is normally accomplished in the following manner. Finger pressure is exerted upon stem 44 of valve 42 to break the seal between mounting member 54 and sealing surface 52 and admit to the passage of product through ports 48 and then to passage 46. Pressure from the propellant located within the containers interior is exerted on bag 18 causing it to collapse toward the longitudinal axis of the container while forcing the product through the valve. This action continues for a time. Because bag 18 is attached to the container at the juncture of top portion 14 and body portion 12, the interior upper portions of the bag begin to follow the interior configuration of cover 38 as product is discharged. As more and more product is dispensed, the propellant pressure causes the bag to squeeze the product towards valve extension 50. Eventually the bag, with essentially all the product discharged, will be collapsed against substantially the entire interior upper surface of cover 38 and valve extension 50. The arch configuration of the bag, together with its film-like consistency and valve extension 50, prevents product islanding by the bag collapsing upon itself. Islanding is the formation of product pockets out of communication with the dispensing valve.

With the dispensing container produced by the present invention it has been found that a much smaller amount of propellant is needed because none of the propellant is exhausted through the dispening valve as the product is dispensed. Thus, the can will hold more product and less propellant in a given volume. It has also been found that only a small amount of pressure is needed to be exerted by the propellant introduced within the dispenser in order to obtain satisfactory discharge of the product. This pressure, on the order of 5 to 10 p.s.i., means there can be a commensurate reduction in the strength requirements of the container making possible the use of less expensive containers further adding to the economy of a dispenser according to the present invention. The low pressure requirements also enhance the safety of the container inasmuch as rupture pressures generated by heat take a longer time to reach.

The economy, fabrication advantages and product versatility obtained through the use of a flexible, elastic bag are all made possible by the process of the present invention. The tensioned contact of the bag about the flange and down the exterior wall of the body prevents failure from seaming and insures that the product is isolated from its propellant. The bag is held firmly in place during seaming by its tensioned contact. Seal failures resulting from gathering or doubling during seaming are avoided by the tensioned contact. Moreover, with the double seam a considerable amount of seal area results, further enhancing the reliability and integrity of the resulting dispenser. The double seam also securely holds the bag during product filling and therefore avoids failure due to bag pullout from its attachment point.

The present invention has been described with reference to the preferred embodiment. However, the spirit and scope of the appended claims should not necessarily be limited to the foregoing description.

What is claimed is:

1. A method of fabricating a pressurized fluid dispening container in which the fluid is stored in a flexible, elastic bag sealed at one end and open at the other end, the container having a rigid, hollow, cylindrical body closed at one end and open at its other end, the outside diameter of the body being greater than the perimeter of the bag, the method comprising the steps of:

(a) placing the open end of the bag over an externally extending radial flange of the body at the open end of the body such that the open end of the bag completely encompasses the radial flange and a portion of the bag is in tensioned contact with a portion of the cylindrical outside surface of the body below the radial flange;

(b) inserting the bag into the interior of the body;

(c) placing a cap over the open end of the body with an annular flange of the cap overlying the bodys radial flange and a downwardly extending portion of the annular flange extending downwardly past the radial flange to the outside thereof; and

(d) seaming the cap and the open end of the body together such that a pressure-tight seal is formed between the bag, the cap and the body by:

(i) bending the annular flange of the cap such that a portion of the downwardly extending portion of the annular flange tucks in under and behind a portion of the bodys flange against the portion of the bag on the outside cylindrical surface of the body; and simultaneously with this bending step;

(ii) bending a portion of the bodys flange downwardly between the tucked in portion and a resulting externally disposed longitudinal portion of the caps flange such that the resulting seam interlocks the open end of the bag between a reverse bend of the bodys flange and a double reverse bend of the caps flange with the open end of the bag being sandwiched between the flange of the cap and the open end of the body for the full extent of the seam.

2. The method claimed in claim 1 wherein the cap has a U-shaped, annular channel portion interiorly of the caps flange and the cap placement step includes inserting the annular channel portion in the open end of the body with the exterior surface of the channel in intimate contact with the bag on the interior side of the body.

3. The method claimed in claim 1 including the additional steps of:

(a) charging the interior of the body on one side of the bag with a fluid to be dispensed; (b) mounting a dispensing valve on the dispenser in fluid communication with the fluid to be dispensed; and

(c) charging the interior of the body on the other side of the bag with a propellant.

4. A method of fabricating a pressurized fluid-dispensing container in which the fluid is stored in a flexible, elastic bag formed of thin-walled plastic tubing linesealed at one end and open at its other end, the container having a rigid, hollow, cylindrical body closed at its bottom and open at its top, the interior circumference of the body being slightly larger than the exterior perimeter of the bag, the method comprising the steps of:

(a) placing the open end of the bag over an externally extending radial flange of the body at the open end of the body such that the open end of the bag completely encompasses the radial flange and a portion of the bag is in tensioned contact with a portion of the cylindrical outside surface of the body below the radial flange;

(b) inserting the bag in the body with the sealed end of the bag proximate the bottom of the body;

(c) placing a cap having a dispensing valve opening over the open end of the body with an annular flange of the cap overlying the bodys radial flange and a downwardly extending portion of the annular flange extending downwardly past the radial flange to the outside thereof;

(d) seaming the cap and the open end of the body together such that a pressure-tight seal is formed between the bag, the cap and the body by:

(i) bending the caps annular flange such that a portion of its downwardly extending portion tucks in under and behind a portion of the bodys flange against the portion of the bag on the outside cylindrical surface of the body; and

(ii) simultaneously bending a portion of the bodys flange downwardly between the tucked in portion and a resulting externally disposed longitudinal portion of the caps flange such that the resulting seam interlocks the open end of the bag between a reverse bend of the bodys flange and a double reverse bend of the caps flange with the open end of the bag being sandwiched between the flange of the cap and the open end of the body for the full extent of the seam;

(e) charging the interior space of the bag with a fluid to be dispensed;

(f) mounting a dispensing valve in the opening in the cap; and

(g) charging the interior space of the body outside the bag with a propellant.

5. The method claimed in claim 4 wherein the cap has a U-shaped, annular channel portion interiorly of the caps flange and the cap placement step includes inserting the annular channel portion in the open end of the body with the exterior surface of the channel in intimate contact with the bag On the interior side of the body.

References Cited UNITED STATES PATENTS 2,689,065 9/1954 Schroeder et a1. 222 2,804,995 9/1957 Fee 222386.5X 2,889,078 6/1959 Thomas 53-3 6X 3,020,688 2/962 Modderno 53-36 3,040,933 6/1962 Everett 22295 THERON E. CONDON, Primary Examiner R. L. SPRUILL, Assistant Examiner US. Cl. X.R. 29-509; 113

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