PLASTIC DISPENSING TUBE HAVING SHAPED CORNERS BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to a plastic dispensing tube with a shaped corner adjacent the shoulder of the tube. The present invention further relates to a plastic dispensing tube having a rectangular or square shoulder with shaped corners. The present invention still further relates to a process for making the plastic dispensing tube having shaped corners.

2. Description of the Prior Art Plastic dispensing tubes are employed commercially to store and dispense a variety of consumer products, such as toothpastes, skin conditioners, sunscreens, shampoos, hair care preparations, and the like.

Conventional dispensing tubes typically comprise a tubular sleeve, a head, and a closure. The head is heat welded or otherwise affixed to an end of the tubular sleeve. The head defines a shoulder and a neck extending from the shoulder with a passageway therethrough. The neck may be externally threaded or beaded to receive a closure, which is in turn internally threaded or beaded.

The end of the tubular sleeve opposite the head is heat sealed after the sleeve is filled with product.

Plastic dispensing tubes are usually made with round shoulders because they correspond in shape to the tube sleeves, which are round in cross-section. Manufacturing tubes having shoulders of shapes other than round requires special techniques to affix heads to tube sleeves. Even with such special techniques, imparting such shapes to tubular sleeves is difficult due to their natural round cross-sectional shape and lack of deadfold memory.

The dispensing tube may be produced by any method known in the art such as extrusion or lamination. In extrusion, a plastic tube sleeve is extruded continuously then cut into discrete lengths that form the body wall of the tube. A tube head is then heat welded to one end of a tube length and a closure is applied to the head. The other open end of the tube sleeve is typically filled with product to be dispensed and then sealed by heat or mechanical means. In lamination, a sheet of plastic material or composite such as plastic/metal is rolled to a tubular shape and sealed along the sheet edges to form a continuous tube or tube sleeve. The tube sleeve is then cut into discrete lengths, head and closure applied, filled with product at the open end, and end sealed in the same manner as an extruded dispensing tube.

The dispensing tube may be manufactured from any plastic material known in the art. Representative plastic materials include ethylene polymers, propylene polymers, polyesters, and polyamides. Useful ethylene polymers include low density polyethylene, medium density polyethylene, high density polyethylene and linear low density polyethylene. A useful propylene polymer is polypropylene. Useful polyesters include polyethylene terephthalate. Preferred plastic materials are low density polyethylene and polypropylene. In a preferred embodiment of the tube, the closure is polypropylene and the tube sleeve is low density polyethylene.

It would be desirable to have a plastic dispensing tube having a shoulders of a shape other than round. It would further be desirable to have a plastic dispensing tube having a shoulder with shaped corners. It would be yet further desirable to have a plastic dispensing tube having a rectangular or square shoulder with shaped corners having ribs that extend a distance into the tubular sleeve.

SUMMARY OF THE INVENTION According to the present invention, there is a plastic dispensing tube having shaped corners. The dispensing tube has a tubular plastic sleeve and a plastic head affixed to one end of the sleeve. The sleeve has an interior surface. The head defines a neck having a passageway therethrough and a shoulder defining one or more corners therein. The head further defines one or more ribs extending from the one or more corners into the sleeve. The one or more ribs is affixed to the interior surface of the sleeve.

According to the present invention, there is a process for making a dispensing tube. A first die is inserted into an end of a tubular sleeve having an interior surface. The first die is mated with a second die. The first and second dies define a mold. The mold defines therein a cavity in the shape of a head defining a neck having a passageway therethrough, a shoulder having one or more corners therein, and one or more ribs extending from the one or more corners. The cavity extends from neck to shoulder from the second die to the first die. A plastic melt is injected into the cavity of the mold to form the head and heat weld it to the end of the sleeve with the ribs of the shoulder extending into and being heat welded to the interior surface of the sleeve.

DESCRIPTION OF THE FIGURES Figure 1 is a perspective view of a tube dispenser of the present invention with ribs shown in hidden lines.

Figure 2 is a perspective view of a first die useful in the process of the present invention.

Figure 3 is a perspective view of a mold having the first die and a second die that is useful in the process of the present invention.

Figure 4 is a cross-sectional view of the mold in conjunction with a sleeve as shown in Figure 7.

Figure 5 is a perspective view of the sleeve being slipped around the first die.

Figure 6 is a view of the first die positioned at the end the sleeve shown partially in perspective and partially hidden.

Figure 7 is a perspective view of the mold positioned at the end the sleeve.

DETAILED DESCRIPTION OF THE INVENTION It was surprisingly found there could be a plastic dispensing tube having a shoulder with shaped corners that extend a distance into the tube sleeve. It was further surprisingly found there could be a plastic dispensing tube having shoulders of a shape other than round that extend a distance into the tube sleeve. It was further surprisingly found there could be a plastic dispensing tube having shoulders of rectangular or square shape that extend a distance into the tube sleeve.

The ribs extending from the corners of the shoulder extend the shape or a facsimile of the shape of the shoulder or shaped corner (s) a distance into the tube sleeve. The ribs provide a degree of mechanical rigidity to the portion of the tube sleeve into which they extend.

The ribs are integrally formed along with the remainder of the head by injection molding. The ribs are affixed to the tube sleeve in the same manner as the head, such as by adhesion or heat welding. Heat welding is preferred. Preferably, the ribs are heat welded to the interior surface of the tube sleeve during injection molding as the plastic melt cools.

The ribs can extend into the tube sleeve for any distance desired. Typically, the ribs will extend into the sleeve up to about two inches and more typically up to about one inch. The width and thickness of the ribs can be selected depending upon the level of rigidity and/or shape conformation desired. Generally, the longer the rib, the longer the shape of the shoulder or shaped corner will extend into the tube sleeve. Further generally, the larger or more rigid the rib, the farther the shape of the shoulder or shaped corner will extend into the sleeve and/or the greater the degree of shape retained. The ribs can have a uniform geometry as they extend into the tube sleeve or they can taper inward or outward in any or all geometric dimensions, such as thickness (height) and width, to the point where the ribs end or terminate in the sleeve. Preferably, the ribs have a thickness or width of up to about 1.5 millimeters.

The ribs can have any cross-section geometry with respect to extension into the sleeve. Preferably, the ribs taper inward (toward the tube sleeve) with respect to all geometric dimensions as they extend into the tube sleeve.

Further preferably, the ribs have a generally semicircular cross-section as they extend into the tube sleeve until tapering to a point of termination.

The shoulder of the dispensing tube can take a variety of shapes. The shoulder defines one or more corners therein. Possible shapes include a teardrop, an oval, a triangle, a rectangle, a square, a pentagon, a hexagon, and other polygons. A rectangular or square shape is preferred.

In the process for making the dispensing tube, a first die is inserted into an end of a tubular sleeve.

The sleeve may be slipped around the first die from above or below. Preferably, the sleeve is slipped around the first die from above. The first die defines one or more corners therein and forms an injection mold when mated with a second die. The injection mold defines therein a cavity in the shape of a head for a dispensing tube. The shape of the cavity corresponding to the head defines a neck having a passageway therethrough, a shoulder having one or more corners therein, and one or more ribs extending from the one or more corners. The cavity extends in shape from neck to shoulder from the second die to the first die. The second die is mated with the first die and a plastic melt is injected through an injection port in the mold into the cavity to form the head, including the shoulder and the ribs. As the plastic melt cools, the shoulder is heat welded to the end or leading edge of the sleeve and the ribs are heat welded to the interior surface of the sleeve.

A tube dispenser of the present invention is shown in Figure 1 and is generally referenced by the numeral 10. Dispenser 10 has a head 18 heat welded to the end of a tube sleeve 14. Head 18 has a shoulder 20, a neck 22, and ribs 26 extending from corners 25. Shoulder 20 has a generally square or rounded square shape when viewed from top or bottom. Ribs 26 extend from corners 25 a distance into tube sleeve 14. Ribs 26 are formed simultaneously with the remainder of head 18 by injection molding and are heat welded to an interior side 27 of tube sleeve 14.

The process of the present invention for making the tube dispenser is seen in part in Figures 5 to 7. Tube sleeve 36 is slipped around a first die 44 (male die) from top (or bottom, if desired) as shown in Figure 5 such that die 32 is substantially covered by but adjacent or proximate to an end of the sleeve 36 as shown in Figure 6. It will be apparent to one skilled in the art that first die 44 may be alternately characterized as being inserted into tube sleeve 36. A second die 40 (female die) is then mated with first die 44 as shown in Figure 7 to form a mold 38. Figure 4 shows a cross- section of mold 38 in conjunction with sleeve 36 along line 4-4 in Figure 7. As shown in Figure 4, mold 38 defines a cavity 50 therein into which a plastic melt (not shown) is injected through an orifice 42 to form a head (not shown). Figure 2 shows first die 44 in isolation. First die 44 defines relief areas 48 at corners 49. Figure 3 shows mold 38 in isolation.

Dispensing tubes may be produced by any method known in the art such as extrusion or lamination. In extrusion, a plastic tube sleeve is extruded continuously then cut into discrete lengths that form the body wall of the tube. A tube head is then heat welded or adhered to one end of a tube sleeve, the top of the neck snipped or removed to open it, and a closure, cap or top is applied to the neck. The other open end of the tube sleeve is typically filled with product to be dispensed and then sealed by heat, adhesive, or mechanical means. In lamination, a sheet of plastic material or composite such as plastic/metal is rolled to a tubular shape and sealed along the sheet edges to form a continuous tube sleeve.

The tube sleeve is cut into discrete lengths, head and closure applied, filled with product at the open end, and the end sealed in the same manner as an extruded tube.

The closure and head may be manufactured according to any method known in the art such as injection molding or stamping with a plastic material. Injection molding is preferred.

The tube dispenser, including the tube sleeve and head, may be manufactured from any plastic material known in the art. Representative plastic materials include ethylene polymers, propylene polymers, polyesters, and polyamides. Useful ethylene polymers include low density polyethylene, medium density polyethylene, high density polyethylene and linear low density polyethylene. A useful propylene polymer is polypropylene. Useful polyesters include polyethylene terephthalate. Preferred plastic materials are low density polyethylene and polypropylene. In a preferred tube dispenser, the tube sleeve is low density polyethylene and the closure is polypropylene. The head will typically be more rigid than the tube sleeve.

The tube dispenser of the present invention will have a tube that is sleeve will be comprised of a material and be of a thickness selected to substantially maintain a tubular shape yet be flexible and substantially non-rigid. The tube sleeve can be squeezed or otherwise mechanically activated to cause product to be dispensed from the tube dispenser. Sleeve thickness will depend upon the plastic material selected, but will preferably range from about 8 to about 32 mils (thousandths of an inch) and more preferably about 13 to about 19 mils.

It should be understood that the foregoing description is only illustrative of the present invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.