US3107838A

US3107838A - Bottom closure for a plastic container

Info

Publication number: US3107838A
Application number: US15332A
Authority: US
Inventors: Louis S Brys; Edwin W Lynn
Original assignee: CELLUPLASTICS Inc
Current assignee: CELLUPLASTICS Inc
Priority date: 1960-03-16
Filing date: 1960-03-16
Publication date: 1963-10-22
Anticipated expiration: 1980-10-22

Description

Oct. 22, 1963 L. s. BRYS ETAL 3,107,838

BOTTOM CLOSURE FOR A PLASTIC CONTAINER Filed March 16. 1960 26 M f FIG 2 k I =1 1 F/Gf 4 INVENTOR$ ED W. LYNN Lo S.BRYS

9111,3101 -zuuw Armg/vns United States Patent() 3,107,838 BOTTOM CLOSURE FOR A PLASTIC CONTAINER Louis S. Brys, Fitchburg, Mass, and Edwin W. Lynn,

Chatham, NJ, assignors, by mesne assignments, to

Celluplastics, Inc, a corporation of New York Filed Mar. 16, 1960, Ser. No. 15,332 7 Qlaims. (Cl. 2295.5)

This invention relates to a plastic container and more particularly to a container which utilizes large diameter flexible plastic tubing for the body of the container.

Thinwall flexible plastic extrusion tubes having a diameter of one inch or more are prone to elastic deformation. The tube becomes out-of-round in a short time since the tube wall is not rigid enough to support its own weight. This out-of-round condition makes it difficult to cement a bottom in the tube and fit a cap over the open mouth to form a container.

in accordance with the present invention there has been devised a molded plastic closure member having an exterior annular flange and an interior plug member which provide between them an annular space or camming area dimensioned to receive the eccentric rim of the tube. As the rim of the open mouth of the tube moves into the camming area the flange and plug member respectively contact the exterior and interior surface of the wall of the tube and cam the eccentric tube back into its original round tubular form. The space between the flange and plug member gradually diminishes in width to form an annular sealing channel in which both of the members bite into the plastic wall of the tube to provide a tight frictional grip for holding the closure in place over the mouth of the tube.

A novel molded plastic bottom is provided for sealing one or" the open ends of the tube. The plastic bottom is in the form of a disk having an upright annular flange with outside diameter slightly larger than the inside diameter of the tube. A beveled edge on the lip of the flange serves to guide the flange into the tube and the tube is slightly stretched as the flange is inserted therein. In order to convert this tight frictional fit into a permanent cemented bond a series of spaced longitudinal grooves are positioned in the outer wall of the annular flange to provide reservoirs which harbor cement and counteract the wiping action of the tube on the wall of the flange. Once the flange is positioned in the tube the cement flows out of the reservoirs through capillary action to bond the plastic bottom to the inner wall and rim of the tube. The uniformity of the bond results in great strength and dimensional stability.

Further advantages and the details of the structure of the present invention may be readily understood by reference to the accompanying drawings in which:

FIG. 1 is a front elevation partly in section of the closure and bottom partially assembled with flexible plastic tube.

FIG. 2 is a perspective view within the annular flange of the molded plastic closure.

FIG. 3 is a perspective view of the molded plastic bottom.

FIG. 4 illustrates the eccentricity of the wall of the ice flexible plastic tube which is perfectly round when molded (dotted lines).

FIG. 5 illustrates a modified form of cap of the present invention in fragment.

As shown in FIGS. 1 and 2 the closure of the container of the present invention comprises a top disc member 10 having an exterior annular flange 12 which is provided with a gripping element in the form of a plurality of spaced ribs 16 which extend down the annular flange. The plug portion of the closure is in the form of a plurality of spaced ribs 14 which are positioned on the disc and each rib 14 is positioned opposite one of the ribs 16 of the flange. The length of the ribs 14 is approximately one half the length of the flange (see FIG. 2).

The cooperating ribs of the flange and plug member provide an annular channel 18 defined by opposite faces of the ribs. The width of the channel 18 is made less than the thickness of the wall 20 of the flexible plastic tube 22 to provide positive pressure or a bite on both sides of the wall of the tube as it travels up through the channel. When the rim of the tube contacts the disc member 10 the closure is positively locked on the tube by the faces of the

ribs

14 and 16.

At the bottom of channel 18

ribs

14 and 16 are tapered away from each other to provide

camming faces

24 and 26 respectively. Cam face 24- is preferably tapered at an angle of about 20 from the vertical to correct large inward eccentricities of the plastic tube 22. Cam face 26 tapers outwardly at a less pronounced angle and merges into the inner wall of the annular flange 12 to correct outward eccentricities of the plastic tube 22. By outward and inward eccentricities we refer to the positive and negative deviations respectively of an out-of-round plastic tube from the average diameter of the tube. The space between the opposite carn faces 24 and 26 is at least twice as wide as the thickness of the plastic tube (FIG. 1) and it has been found that such width is adequate to correct the eccentricity of flexible tubes produced in normal commercial operations. When the closure 10 is fitted over the rim of a flexible tube 22 cam faces 24 land 26 respectively exert outward and inward pres sure against the eccentric portions of the rim of the tube and thereby shape the rim into a circle as it travels upwardly toward the bottom of the annular channel 18. The taper of cam faces 24 and 26 causes the corrective outward and inward pressure to gradually increase so that at the time the rim of the tube enters annular channel 18 it is perfectly rounded and eccentricity is eliminated. The modified form of closure shown in FIG. 5 is identical with that of FIG. 1 with the exception that ribs 27 on the exterior flange of the cap are made approxi mately twice as wide as the ribs of the plug member (see FIG. 2.). The wide rib gives additional surface contact with the wall of the tube and this may be found desirable in some applications for increasing the frictional grip of the cap on the wall of the tube.

Ribs

16 and 27 which are spaced around the inner wall of annular flange 12 at regular intervals, are highly eifective for achieving proper initial engagement between the closure and the eccentric plastic tube. The arced spaces between these ribs provide a series of channels into which the outwardly eccentric portions of the tube can freely enter without impeding the upward travel of the tube as would otherwise be the case where the rim at the mouth of the tube is caused to enter an annular slot with continuous side walls. As a result the tapered ends of the ribs can readily engage and cam the rim of the plastic tube without interference from the outwardly eccentric pontions when the closure is first fitted over the mouth of the tube. Also, if portions of the rim of the tube become permanently bowed or otherwise distorted due to the pinch of the opposed ribs of the closure and long use of the container, the arced sppaces between the ribs 16 and 2.7 readily accept the distorted portions of the tube and maintain the effectiveness of the closure in frictionally gripping the mouth of the tube.

As shown in FIGS. 1 and 3 the molded plastic bottom 28 for the tube consists of a disk 39 which has an annular flange 32. In the bottom shown, as a small lip 34 projecting out beyond the exterior side wall of the flange is provided around the rim of the flange. However, the lip is not essential and if desired can be eliminated. A series of longitudinal grooves 36 are cut into the exterior wall surface of the annular flange 32 and these are spaced around the entire flange at regular intervals. The upper edge 38 of the flange is beveled at approximately a 45 angle so that the molded bottom 28 can be easily inserted into the eccentric tube.

Prior to assembly the annular flange 32 of the plastic bottom 28 is coated with cement which fills the grooves 36. As shown in 'FIG. 1 the bottom 23 is then inserted into the plastic tube 22 and since the inside diameter of the tube is slightly less than the outer diameter of the annular flange 32 substantially all of the cement is wiped oil the wall surfaces of the flange which frictionally engage the inner wall of the tube. The cement which is wiped off is deposited on lip 34 which is thereby bonded to the rim of the tube. The grooves 36, however, remain filled with cement and after the rim of tube 22 has been seated upon the lip 34 the cement flows out of the grooves through capillary action into the minute spaces between the frictionally engaged surfaces of the tube and the annular flange. The cement bonds the wall of the annular flange up to the beveled edge 38 to the tube in a uniform manner which gives great strength and dimensional stability. The final container can be used to hold heavy objects without the danger of the bottom falling out of the tube. The closure and bottom member of the present invention are rigid pieces as compared to the flexible thinwall plastic extrusion tubes and particular advantage achieved in small containers where the length of the tube does not exceed its diameter. In such case the rigid closure and bottom member so strengthen the wall of the r tube that there is no tendency for the wall to collapse even when packaging heavy objects.

As to materials the tube of the container of the present invention is a large diameter flexible thinwall plastic extrusion tube. The term large diameter as used herein is intended to mean extrusion tubes at least one inch in diameter and the term thinwall is intended to mean plastiic extrusion tubing having a wall thickness less than about 0.020 inch. The tubing may be made of polyethylene, polypropylene, polystyrene, cellulose acetate, cellulose butyrate, vinyls, nylon and the like. The closure and bottom can be molded out of any rigid plastic material such as polystyrene, cellulose esters, polymerized acrylate and methacrylate esters, polypropylene, vinyls, polyamides, acrylics, ureas and the like. Since the closure is adapted to shape and mold the tube back into a circle and the bottom member is adapted to stretch the tube it is necessary that these members have greater rigidity than the tube. The required rigidity may be achieved by proper selection of material or thickness of the operating parts.

Suitable cements for bonding these materials to the plastic materials mentioned for the tube are well known in the art and will not be described in detail herein. In some cases the cement can consist of mixtures of cement and suitable solvents or of solvents alone which are known to be able to weld the same or different plastic materials together by solvation. We have achieved excellent results with a solvent consisting of acetone, methyl cellosolve and toluene. These readily fused the cellulose acetate butyrate material used.

While the preferred embodiment of the closure shown includes a series of spaced ribs integral with the inner wall of the annular flange 12, if desired the

ribs

16 or 27 need not be spaced apart and may form a continuous tapered annular band (not shown) extending around the entire wall of the flange. In this case the annular band, having a taper at its lower end in the same direction as that of the ribs -16, engages and cams the entire rim of the eccentric plastic tube and then cooperates with the spaced ribs 14 to bite into the wall of the tube and hold the cap in place over the mouth of the tube. Such a structure is not near ly as eflective for achieving proper initial engagement with the rim of the eccentric plastic tube, especially when the closure and tube are assembled with automatic capping machinery. However, the product has commercial utility.

In the preferred form of structure shown in the drawings the ends of ribs 14 which contact the Wall of the plastic tube are curved so that the ribs present a blunt surface for.

contact with the wall of the tube. This is not essential overall configuration of the ribs may also be changed to any desired form provided the ribs present an end surface which will contact the tube in the manner described for ribs 14.

As shown in FIG. 1 the closure 10 has a circular stud 4-0 on the top surface to provide a stacking feature whereby the assembled containers can be securely stored one over the other. Additional non-essential changes in the details of construction will be obvious to those skilled in the art.

It will be understood that it is intended to cover all changes and modifications of the preferred embodiment of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.

We claim:

1. A bottom for permanently sealing the open end of an out-of-round flexible thinwall plastic tube which cornprises a disc having a side wall in the form of an annular flange, the outer surface of the side wall of the flange having a plurality of grooves spaced around the wall at regular intervals which are adapted to hold cement, the outer diameter of the side wall being slightly greater than the inner diameter of the flexible plastic tube whereby the entire outer surface of the side wall except for the grooves therein engages and exerts pressure on the inner wall of the tube and whereby the cement in the grooves flows into the spaces between the engaged surfaces by capillary flow to seal the bottom to the inner wall of the tube when the bottom is inserted into the open end of the tube.

2. A structure as specified in claim 1 in which the upper edge of the annular flange of the bottom is bevelled.

3. A structure as specified in claim 1 in which the lower edge of the side wall is extended outwardly to form a small lip which projects out beyond the flange whereby th rim of the tube rests upon said lip when the bottom is inserted into and pressed against the open end of the tube.

4. An improved plastic container which comprises the combination of a flexible thinwall plastic tube sealed at one end thereof, and a bottom for the tube which comprises a disc having a side wall in the form of an annular flange, the outer surface of the side wall of the flange having a plurality of grooves spaced around the wall at regular intervals which are adapted to hold cement, the outer diameter of the side wall being slightly greater than the inner diameter of the flexible plastic tube whereby the entire outer surface of the side wall except for the grooves therein engages and exerts pressure on the inner wall of the tube and whereby the cement in the grooves flows into the space between the engaged surfaces by capillary flow to seal the bottom to the inner wall of the tube when the bottom is inserted into the open end of the tube.

5. A structure as specified in claim 4 in which the upper edge of the annular flange of the bottom is bevelled.

6. An improved plastic container which comprises the combination of a flexible thinwall plastic tube sealed at one end thereof, and a bottom for the tube which comprises a disc having a side wall in the form of an annular flange, the lower edge of the side wall being extended outwardly to form a small l-ip which projects out beyond the flange, the outer surface of the side Wall of the flange above the lip having a plurality of grooves spaced around the wall at regular intervals which are adapted to hold cement, the outer diameter of the side wall being slightly greater than the inner diameter of the flexible plastic tube whereby the entire outer surface of the side wall except for the grooves therein engages and exerts pressure on the inner wall of the tube and whereby the cement in the grooves fiows into the spaces between the engaged surv 5 faces by capillary fiow to seal the bottom and lip thereof to the inner wall and rim of the tube respectively when the bottom is inserted into and pressed against the open end of the tube.

7. A structure as specified in claim 6 in which the upper edge of the annular flange is bevelled.

References Cited in the file of this patent UNITED STATES PATENTS 1,454,846 Coates May 15, 1923 2,412,004 OBrien Dec. 3,1946 2,528,948 Cosmo Nov. 7, 1950 2,802,593 Slaughter Aug. 13, 1957 2,814,428 Magill Nov. 26, 1957 2,819,007 Bergstrom Ian. 7, 1958 2,827,218 Wilcox Mar. 18, 1958 2,872,031 Lindberg Feb. 3, 1959 r 2,922,563 Aldington' Jan. 26, 1960 2,947,463 Conklin Aug. 2, 1960 2,974,825 Ross Mar. v14, 1961

Claims

1. A BOTTOM FOR PERMANENTLY SEALING THE OPEN END OF AN OUT-OF-ROUND FLEXIBLE THINWALL PLASTIC TUBE WHICH COMPRISES A DISC HAVING A SIDE WALL IN THE FORM OF AN ANNULAR FLANGE, THE OUTER SURFACE OF THE SIDE WALL OF THE FLANGE HAVING A PLURALITY OF GROOVES SPACED AROUND THE WALL AT REGULAR INTERVALS WHICH ARE ADAPTED TO HOLD CEMENT, THE OUTER DIAMETER OF THE SIDE WALL BEING SLIGHTLY GREATER THAN THE INNER DIAMETER OF THE FLEXIBLE PLASTIC TUBE WHEREBY THE ENTIRE OUTER SURFACE OF THE SIDE WALL EXCEPT FOR THE GROOVES THEREIN ENGAGES AND EXERTS PRESSURE ON THE INNER WALL OF THE RUBE AND WHEREBY THE CEMENT IN THE GROOVES FLOWS INTO THE SPACES BETWEEN THE ENGAGED SURFACES BY CAPILLARY FLOW TO SEAL THE BOTTOM TO THE INNER WALL OF THE TUBE WHEN THE BOTTOM IS INSERTED INTO THE OPEN END OF THE TUBE.