IE47379B1 - Collapsible dispensing tube - Google Patents

Description

The present invention relates to a collapsible container having a tubular body and a thermoplastic headpiece which comprises an annular frusto conical shoulder which may be provided with a cylindrical extension on which screw threads are mounted for receiving a cap, as well as an impermeable barrier member within the tubular body and fixed to the inner wall of the headpiece. The barrier member has an extreme edge having at least a substantially part thereof engaging the adjacent inner wall of the tubular body.

The manufacture and fabrication of tubular articles of thermoplastic material such as collapsible tubes are known and U.S. Patent No. 2,673,374 to Strahm discloses a method of manufacturing a tubular product in which a thin-walled plastic tube is formed and a shoulder and screw-threaded cylindrical part affixed thereto by injection molding thereby forming a tubular plastic article with a headpiece. An improvement to the Strahm patent was U.S. Patent No. 3,172,571 to Marchak in which a tubular body for a collapsible tube is formed of a laminated construction having an intermediate layer that is impervious to the contents of the tube while recognizing that some loss of moisture or product contents of the tube could take place through the plastic head. Marchak further stated that losses were held to a minimum because of the relatively thick plastic head. In U.S. Patent No. 3,565,293 - 3 applicant had constructed a collapsible dispensing container with a deformable body of low permeability and laminated construction, a thermoplastic headpiece, and an insert disc in the form of a barrier member that substantially eliminates product losses and which is spaced from the inner wall of the collapsible tube. The headpiece is provided with an annular lip underlying the peripheral edge of the barrier member.

The present invention seeks to provide an improved collapsible container and a method of making the same wherein higher pressures are built up thereby resulting in a reduced temperature and a faster fabricating cycle.

According to one aspect of this invention there is provided a collapsible container having a tubular body, a headpiece of thermoplastics material molded to one end thereof, an impermeable barrier member fixed to the inner wall surface of said headpiece and provided with an extreme peripheral edge having at least a major part thereof which engages the adjacent inner wall of said tubular body both the tubular body and extreme peripheral edge being tapered at an angle to the longitudinal axis of the tubular body, and means on said barrier member for securely anchoring said barrier member to the adjacent surface of said headpiece.

According to a further aspect of this invention, there is provided a method of making a collapsible container provided with a headpiece of thermoplastic material comprising: inserting a flexible tube over a tapered mandrel which is arranged to co-operate with a correspondingly tapered die, inserting between said mandrel and die an impermeable barrier msmber, engaging said tapered mandrel and said tube with the correspondingly tapered die whereby said tube is held tightly therebetween and the top of said tube is bent at an angle - 4 inwardly relative to the longitudinal axis of the tube and injecting a thermoplastic material defining the headpiece through a molding gate over said barrier member which has at least a major part of its extreme peripheral edge engaging the adjacent inner wall of the bent portion of the top of said tubular body and means for securely anchoring said barrier member to the adjacent surface of said headpiece.

In order that the invention will be more clearly understood, it will now be disclosed, by way of example, with reference to the accompanying drawings, in which:FIGURE 1 is a sectional view of a collapsible container showing the headpiece and barrier member being formed by a die and mandrel in accordance with the teaching of the method of the invention; FIGURE 2 is a sectional view of the completed collapsible container combination as fabricated in Figure 1; FIGURE 3 is a partial irlevational and a partial sectional view of another embodiment of the present invention; FIGURE 4 is another embodiment of the present invention illustrating a nethod of manufacture of a collapsible tube having squared shoulders; FIGURE 5 is a fragmentary enlarged section of Figure 3 showing the laminated collapsible tube structure; FIGURE 6 is a partial sectional view of a further modification of the present invention; FIGURE 7 is a partial elevational view of 7 3 7 9 - 5 the embodiment shown in Figure 6, taken along the lines 7-7 of Figure 6; FIGURE 8 is a partial sectional view, similar to Figure 6, however showing an alternate embodiment of the present invention? and FIGURE 8a is a further partial sectional view of another embodiment of the present invention.

A collapsible container is shown in Figure 1 of the type such as is used for the dispensing of toothpaste and which is referred to generally by the reference numeral 8. The tubular body has a three-ply laminated construction having inner and outer thermoplastic layers 12 and 16 and intermediate layer 14 constituting, for example, metal foil. The headpiece 18 for the tubular body comprises an easily moldable thermoplastic material such as low density polyethylene and includes a threaded neck portion 20 which is adaptable to receive a screw cap (not shown).

Referring to Figure 1, the method of manufacturing the present collapsible container is shown in which a thermoplastic collapsible laminated tube with a foil intermediate layer, and outer and inner layers of low density polyethylene is slid over a tapered mandrel 22 and the entire assembly pushed into a tapered die 24. Thread plates 26 move laterally to engage the neck portion 20 to form threads thereon. Thus, the tube 8 initially fits loosely on the mandrel 22 and as the tapered die 24 moves down the axis the top of the tube is bent about 10°, however, it is within the scope of the present invention to bend the top of tube 8 to any selected angle between 5° to 20°. Furthermore, a space 28 is formed between the mandrel 22 and the adjacent inner surface of the tube 8. A molding gate 30 is located at the top of the assembly which permits the injection - 6 molding of plastic material therein forming a headpiece 18 locking in barrier member 32. The barrier member 32 is provided with an angular, annular peripheral edge surface 34 that engages a correspondingly angled inner wall 36 of the tubular body 8. The locking taper formed by the aforesaid angled surfaces at A is clearly shown which permits the building up of high pressures in the manufacturing process with the desirable result of obtaining a faster process cycle as well as a better bond between the headpiece, barrier insert and tubular body. Moreover, the locking taper configuration provides another clearly desirable result in that blowby of the thermoplastic material is virtually eliminated upon the injection of the plastic material. In order to ensure the reliable anchoring of the barrier member 32 to headpiece 18, the barrier member is provided with a lower bead 38 and upper beads 40. In this regard, it should be pointed out that the lower bead 38, although it assists in anchoring the barrier member, it is not essential to achieve the desired result.

It should be apparent that there is a choice of desirable fabricating material since the temperature required for the process can be varied thereby permitting a faster cycle. For example, a lower heat may be employed so that low density polyethylene can be used in the manufacturing process.

It should be pointed out that known collapsible laminated dispensing tubes must use a higher melting high density thermoplastic material since the intermediate metallic layer, such as aluminium acts as a heat sink, and therefore more heat must be supplied in order to achieve a bonding of the parts of the collapsible container. On the other hand, the present invention allows more pressure to be applied, which achieves a better heat transfer and consequently a - 7 better adhesion between the assembled parts of the collapsible dispensing container, and aLso allows the use of lower density polyethylene which softens at a lower temperature.

It is evident from a study of Figure 1 of the drawings that the novel process resulting in the bending inwardly of the top of tube 8 at A, together with a corresponding bevelled surface 34 of the barrier member 32, as well as the concomitant increases in pressure and the ability to lower the temperature, results in an exceptionally good bond of the tube, the thermoplastic headpieca and the barrier insert. Furthermore, the heat insulating characteristics of the present structure enha ices the welding process. Moreover, the fact that the peripheral annular edge surface 34 of the barrier insert engages an inner surface of the tube 10 al:>ng its entire circumference prevents the flow of thermoplastic material against the tooling during the injection molding steps. This condition results in an insulating effect whereby the heat generated will be shunted to the laminated tube structure thereby permitting lower temperature.

Since the barrier member 32 has its free edge circumferentially engaging the inner wall of tube 10, there is no cantilever effect on that member as was the case in U.S. Patent No. 3,565,293. Thus, in the prior art construction it was necessary to have a barrier member that was thick and stiff enough to withstand the forces generated by both high temperatures and pressure. Consequently, in accordance with the teachings of the present invention, a relatively thin, flexible barrier member could be used in place of the conventional rigid insert presently being employed. This relatively thin barrier member will function to prevent bypass of gases around its peripheral edge since it is either in substantial engagement, or with full engagement with the adjacent inner wall of the tube 8. - 8 Referring to Figures 3 and 5, an alternative embodiment of the present invention is shown having a barrier insert member referred to generally by the numeral 42 that is castellated on its peripheral edge to form alternate projecting sections 46 and recessed sections 44. The projecting sections 46 abut the adjacent interior wall of the collapsible tube 8 while the recessed sections 44, as seen in Figures 3 and 5, receive a flow of thermoplastic material 48 that assists in anchoring the barrier insert member 42 to the headpiece 18 as well as to tube 8. It will be noted that the thermoplastic material 48 is located between the barrier insert member and an inner surface of the tube wall which is spaced therefrom at spaced locations about the circumference of the barrier insert member, but with substantially engagement by the peripheral surface of the projection portions of the barrier insert member along the adjacent inner wall of tube 8. A tapered die and a tapered mandrel, such as shown in Figure 1 and described hereinbefore, is employed in the present arrangement. Figure 4 in which the headpiece is a substantially frusto conical shoulder, shows the method of bending the top of tube 8 and forming a square shoulder tube 18a. The barrier insert member 42 is in a castellated form having spaced projections that engage a substantial portion of the inner wall of the tube 8, similar to the construction shown in Figure 3 and having thermoplastic material 48 that flows into the spaces between the projections. It will be observed from Figure 4 that the top edge 8a of the tube 8 is relatively straight and does not curl inwardly. This construction is possible since there is sufficient strong squeeze of the laminates 12, 14 and 16 between the tapered die 24 and tapered mandrel 22 to allow high injection pressure without forcing the laminates downwardly. Therefore, this arrangement pezmits the conicalshaped top of the tube to be squared off, hence present47379 - 9 ing a different appearance of the tube, which conventionally has rounded shoulders, as seen in Figure 3.

Figures 6 and 7 show a further embodiment of the present invention in which the barrier insert member 50 is provided with spaced holes 52 that are cut into the member 50 so that the thermoplastic material 54, upon injection molding, flows through the barrier holes 52 and functions to anchor the barrier insert member 50 to the headpiece 18 as well as the tube 8. The spaced holes 52 serve to define a castellated edge on the barrier insert member 50.

Figure 8 is another alternative embodiment of the present invention and is similar to the construction illustrated in Figure 6. Hcsrever the mandrel 22 has a groove 23 which permits the inward flow of thermoplastic material forming the headpiece 18 through the holes 52 to create an annular ring 55 below the barrier insert member 50. This arrangement functions to further strengthen the anchor of member 50 to the headpiece 18 and collapsible tube 8.

Figure 8a is a further embodiment of the present invention which is similar to the construction shown in Figure 8, however disclosing spaced grooves 56 that permit the flow of thermoplastic material from the headpiece 18 into an annular ring 58. The latter construction results in a reliable securement for the member 50.

A desirable result of the construction and method of manufacture, as set forth herein, is the production of a collapsible dispensing container of the laminated type in which a material may be selected from a choice of fabricating material especially for the specific use intended.

Claims (21)

1. A collapsible container having a tubular body, a headpiece of thermoplastics material molded to one end thereof, an impermeable barrier member fixed to the inner wall surface of said headpiece and provided with an extreme peripheral edge having at least a major part thereof which engages the adjacent inner wall of said tubular body both the tubular body and extreme peripheral edge being tapered at an angle to the longitudinal axis of the tubular body, and means on said barrier member for securely anchoring said barrier member to the adjacent surface of said headpiece.

2. A container as claimed in Claim 1, wherein said angle is between 5° and 20°.

3. A container as claimed in Claim 1 or 2, wherein said angle is 10°.

4. A container as claimed in Claim 1, 2 or 3, wherein the entire extreme peripheral edge of said barrier member engages the adjacent inner wall of said tubular body.

5. A container as claimed in any one of the preceding claims, wherein said means on said barrier member comprises a bead in a lower portion of said barrier member in the region of the extreme peripheral edge thereof, said bead being embedded in said thermoplastic headpiece to thereby assist in the anchoring of the barrier member to said headpiece.

6. A container as claimed in any one of the preceding claims, wherein the entire extreme peripheral edge of said barrier member is annular. - 11

7. A container as claimed in Claim 1, 2 or 3, wherein said extreme peripheral edga is castellated, and the areas therebetween having thermoplastic material of said headpiece therein.

8. A container as claimed in Claim 7, wherein at least one radial surface, lying in a plane parallel to the longitudinal axis of the container, of at least one of said castellations on the extreme peripheral edge diverges relative to the facing radial surface of the adjacent castellation whereby the thermoplastic material that fills the space between the adjacent castellations mechanically wedge the barrier member against said headpiece.

9. A container as claimed in Claim 1, 2 or 3, wherein there is provided a plurality of spaced openings in the lower portion of said barrier member in the region of the extreme peripheral edge thereof which perforate the barrier member, said spaced openings having thermoplastic material of said headpiece therein whereby said barrier member, headpiece and tubular body are securely anchored together.

10. A container as claimed in Claim 9, wherein said lower portion of said barrier member is L-shaped.

11. A container as claimed in Claim 5, wherein said lower portion of said barrier member is L-shaped, and said bead is located at the top of said L.

12. A container as claimed in Claim 9, wherein said headpiece includes an annular ring constituted of the same thermoplastic material that is present in said spaced openings, and integral with said material in said openings.

13. A container as claimed in Claim 9, wherein - 12 said headpiece includes annular ring of thermoplastic material under the extreme peripheral edge of said barrier member, and spaced channels connecting said spaced openings with said annular ring which is formed integrally with said headpiece.

14. A method of making a collapsible container provided with a headpiece of thermoplastic material comprising: inserting a flexible tube over a tapered mandrel which is arranged to co-operate with a correspondingly tapered die, inserting between said mandrel and die an· impermeable barrier member, engaging said tapered mandrel and said tube with the corresponding tapered die whereby said tube is held tightly therebetween and the top of said tube is bent at an angle inwardly relative to the longitudinal axis of the tube and injecting a thermoplastic material defining the headpiece through a molding gate over said barrier member which has at least a major part of its extreme peripheral edge engaging the adjacent inner wall of the bent portion of the top of said tubular body and means for securely anchoring said barrier member to the adjacent surface of said headpiece.

15. The method as claimed in Claim 14, wherein the part of said peripheral edge engaging the adjacent inner wall of said tubular body is bevelled at an angle which corresponds with the angle of bend of said top of the tube.

16. The method as claimed in Claim 14, wherein said tube initially fits loosely over said tapered mandrel, and a space is formed between said mandrel and the adjacent unbent portion of said tube.

17. The method as claimed in any of Claims 14 to 16, wherein said tubular body is a laminate. - 13

18. A method of making a collapsible container as claimed in any of Claims 14 to 17, wherein said barrier member is provided with castellations at the lower peripheral edge thereof, said tapered mandrel having an annular groove adjacent to said spaced openings whereby when said headpiece is injection molded thermoplastic material flows through the spaced openings of said castellations and into a space formed by said groove in the mandrel to form an internal annular ring on said headpiece.

19. A method of making a collapsible container as claimed in any of Claims 14 to 17, wherein said barrier member is provided with castellations at the lower peripheral edge thereof, and thermoplastic material is molded through spaced channels connected to the openings of said castellations and under a part of said barrier member to a chamber located under said extreme peripheral edge of the barrier member to form an annular ring that is integral with said headpiece.

20. A collapsible container substantially as herein described with reference to, and as illustrated in, Figures 1 and 2, or 3 and 5, or 4, or 6 and 7, or 8, or 8a of the accompanying drawings.

21. A method of making a collapsible container substantially as herein described with reference to, and as illustrated in, Figures 1 and 2, or 3 and 5, or 4, or 6 and 7, or 8, or 8a of the accompanying drawings.