Dispensing – Collapsible wall-type container
Reexamination Certificate
1999-08-06
2001-01-09
Shaver, Kevin (Department: 3754)
Dispensing
Collapsible wall-type container
C222S107000, C222S569000
Reexamination Certificate
active
06170705
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a double-walled tube constituted by an outer metal envelope and a protective, flexible inner envelope intended to store and dispense detergent products, hygiene products or cosmetic products, such as hair dyes, that are particularly corrosive to the outer metal envelope.
BACKGROUND ART
Metal tubes are appreciated for their high restitution rate. Also the perfect plasticity of the metal prevents any of the product returning inside the tube when the operator has finished pressing the skirt of the tube. On the other hand, the metal tube is subjected to corrosion when it contains particularly acidic or alkaline products.
Attempts consisting in coating the inner surface of metal tubes with varnish have proved unsuccessful: the deposited coat is never very regular, it holds more or less well onto the surface, it is fragile and cracks after the tube has been used a number of times. Cracks appear through which the product passes and eventually corrodes the metal. Also, the ends of the tube, i.e. the neck at one end and the open end at the other through which the tube is filled and that is then flattened and folded to seal the tube, are not protected or are insufficiently protected by the varnish.
French patent application 2 322 058 discloses a double-walled tube constituted by two separate tubes that are connected at the necks. The metal tube constitutes an outer envelope that is protected from the corrosive product by a plastic inner tube. The top end of the neck of the inner plastic tube projects far beyond the top of the neck of the external metal tube. The projected section flares out in a trumpet shape above the metal neck and is then embedded into a plastic end molded above and around the metal neck. Three separate operations are required to produce a tube of this kind: the insertion of the inner tube into the outer tube, the flaring of the projected end of the neck of the inner tube and then the difficult molding of a plastic collar onto the edge of the outer metal neck.
Patent application J07277349 describes a double-walled tube that is also constituted by two separate tubes but that are connected together at the neck by a nozzle that is tightly threaded around the assembly. As in French patent application 2 322 058, the top end of the neck of the inner tube projects well beyond the top end of the outer metal tube. The projecting section is flared and then folded outwards covering the outer metal neck. The nozzle is tightly threaded and bears on the folded section of the inner tube. In order to ensure that the connection is leaktight J07277349 recommends that at least one surface of the ends of the inner tube, which is made of plastic, has a smooth surface without a mold joint line. A smooth surface of this kind is achieved by injection-molding the inner tube.
The end of the neck of the inner plastic tube must be thin enough in order for it to be folded over the top end of the neck and to cover the lateral outer surface of the metal neck. The thinness of the inner plastic tube means that it is prone to buckling and it does not facilitate the first shaping stage in which the neck is flared. This essential stage is complicated by the need to design tooling to hold the neck steady when it is flared. Also, with large capacity tubes that must have a skirt length of over 130 millimeters injection-molding cannot easily be used to produce a thin, plastic neck able to withstand cracking under strain. These tubes require materials to be used that are suitable for being injected in a long, narrow air gap. Materials of this kind must have a high melt index that is higher than 15 and they are much more prone to cracking under strain when they are brought into contact with the contained product than the materials generally used with a much lower melt index (0.2 to 2).
Also, it would be preferable to produce the inner plastic tube using other, more economical, means, for example using extrusion blow-molding or by molding a head onto an extruded or welded laminated skirt. In order to achieve this, the need to have an outer surface without any protrusions, such as a molding joint line, would have to be set aside, as would the need to obtain a neck shape that could be series-produced. Both these conditions are necessary in J07277349 in order to obtain complete leaktightness of the connection between the necks.
PROBLEM POSED
Therefore, the applicant has attempted to produce a double-walled tube constituted by a protective, flexible inner envelope and an outer metal envelope intended to store and dispense products that are corrosive to the outer metal envelope, the two envelopes being connected together at the ends, the connection at the necks having improved leaktightness, particularly for long tubes.
DISCLOSURE OF THE INVENTION
A first aim of the invention relates to a double-walled tube comprising an internal tube having a skirt, a shoulder and a neck hereafter called “inner neck” that defines an opening hereafter called “inner opening”, a metal tube having a skirt, a shoulder and a neck hereafter called “outer neck”, provided with snap-on means on the outer wall, the two tubes being connected together at the neck by a nozzle that comprises a base and at least one outer skirt that grips said two necks and that is provided with additional snap-on means to the snap-on means of the outer neck, characterized in that the nozzle is provided with an inner skirt the outer surface of which has an overall tapered profile such that when the nozzle is forced downward said inner skirt causes the circumferences of the central parts of the neck to expand and the ends of said necks to flare.
When the nozzle is forced downward the base of the nozzle is not brought to bear on the edges of the inner and outer necks. In other words, significant play, greater than some tenths of a millimeter, exists between the base of the nozzle and said edges. The outer diameter of the section of the inner skirt of the nozzle that is inserted into the inner neck is greater than the initial diameter of the inner opening of the inner opening over a length that is at least equal to 2 millimeters.
The inner tube can be made of any flexible substance capable of protecting the outer metal envelope from any corrosive product contained within. Preferably, the inner tube is plastic. It is obtained using any known means such as injection molding, extrusion blow-molding, molding the head then welding it onto an extruded or welded laminated skirt. The neck is not provided with hollow or protruding features but may comprise mold joint lines. The neck is sufficiently thick to avoid becoming buckled when the nozzle is depressed on the necks. The shape of this cylindrical, hollow neck should preferably have a height and thickness relation lower than 10 in order to avoid concertina-type distortion of said neck.
The outer tube is metal. It comprises a skirt, a shoulder and a neck. The inner tube is inserted in the outer tube before the nozzle is depressed. Given that the outer diameter of the inner neck is more or less equal to or very slightly less than the inner diameter of the outer neck the two necks are very close to each other at a certain height that is common to their outer and inner surfaces respectively. The inner neck does not project beyond, or only very slightly beyond, the outer neck: it is not necessary for it to be folded over the end of the outer neck.
The outer appearance of the nozzle resembles nozzles of the prior art. It may be provided with an outer skirt that has means, on the outer surface, for connecting it to a stopper, for example that is threaded. It is firmly held in place covering the outer neck by fastening means such as snap-on flanges that are located respectively on the outer surface of the outer neck and on the inner surface of the outer skirt of the nozzle. If the tube is intended to be sealed by a cap or a stopper being screwed into the outer surface of the nozzle the outer skirt is provided with a thread on the outer surface and the inner surface, that
Bodet Herv{acute over (e)}
Schneider Bernard
Cebal SA
Deal David
Pollock, Vande Sande & Amernick, R.L.L.P.
Shaver Kevin
LandOfFree
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