FR2798363A1 - One-piece polypropylene stopper for bottle, has base, internally threaded outer skirt for engaging bottle neck and coaxial inner skirt with outwardly extending rims sealing with neck interior - Google Patents

Abstract

A one-piece polypropylene stopper has a base (3) with an internal face (31) for abutting the end of a container neck (12), an internally threaded outer skirt (4) for engaging a thread on the outside of the neck and a coaxial inner skirt (7) with outwardly extending rims for sealing with the interior of the neck. An Independent claim is included for forming the above stopper, then making a cut line (6) near the free end of the outer skirt in order to form a tamper-proof band.

Description

The present invention relates to plastic caps for containers, such as bottles.

One-piece plugs of plastic material in the form of a shell are already known, intended for closing the neck of containers, said shell comprising a bottom, the inner face of which is capable of being applied against the end face. annular of said neck; an outer lateral skirt, carried by the periphery of said bottom adapted to surround said neck externally, the inner wall of said skirt the outer side bearing a thread adapted to cooperate with a thread carried by the outer wall of said neck to fix said stopper on said lot; - An inner skirt, carried by said bottom and coaxial with said outer side skirt, said inner skirt being adapted to penetrate into said neck ensuring a sealed contact with the inner wall of the latter.

such known plugs, generally intended to be mounted on the neck of bottles made of plastic or glass and containing mineral water or still or carbonated drinks, are most often made by injection molding of a high density polyethylene. such polyethylene, which is a relatively soft material of relatively low hardness, communicates to said plugs particularly interesting properties - said inner skirt can be applied over its entire height against the inner neck wall ensuring a perfect seal, however without causing a significant friction susceptible to make difficult, if not impossible, the separation of the plugs of the necks on which they are mounted - likewise, the screwing and unscrewing of the plugs are easy, fileta ges said plugs cooperating with a reduced friction with the threads of said necks; and - the ejection of the plugs out of the molds in which they are made is a ", because the friction with the walls of said molds are relatively weak.

However, these known plugs have drawbacks. Firstly, polyethylene is an expensive material, so said plugs are themselves expensive. This disadvantage is further etched because the polyethylene is relatively soft and not hard, it is necessary to make said plugs with thick walls, which increases the mass of polyethylene to use and therefore the cost of said plugs. Moreover, when, in a known manner, said plugs comprise a tamper-evident ring extending the edge of said outer lateral skirt and connected thereto by a tear line, it is necessary, in order to allow a correct separation of the inviolability ring despite the flexibility and low hardness of polyethylene, to provide such a tear line formed complex patterns - notches, bridges, etc ...- increasing the complexity and cost of injection molds.

The object of the present invention is to remedy these disadvantages. It relates to a plug whose sealing, screwing, unscrewing and unmolding are as advantageous as those of the polyethylene plugs described above, but whose cost is much lower.

To this end, according to the invention, the cap in one piece of plastic material in the form of a shell, intended for closing the neck of a container, a bottle, said shell comprising - a bottom, whose face internal is adapted to be applied against the annular end face of said neck; an outer lateral skirt carried by the periphery of said bottom and capable of wrapping said neck externally, the inner wall of said outer skirt bearing a thread capable of cooperating with a thread carried on the outer wall of said neck to fix said stopper on said - inner skirt, carried by said bottom and coaxial with said outer side skirt, said inner skirt being adapted to penetrate into said neck ensuring a sealed contact with the inner wall of the latter, remarkable - that it is made of polypropylene; and that said inner skirt comprises at least one circumferential bead in the direction of said outer lateral skirt and able to apply sealingly against the inner wall of said neck.

Thus, since polypropylene is substantially less expensive than polyethylene, the cost of the plug according to the present invention can be much lower than that of known plugs. In addition, the polypropylene being more rigid and harder than polyethylene, the walls of the plug according to the present invention may be thinner than those of the known plug, which leads to a saving in material and therefore a further reduction in the cost of the plug. polypropylene cap according to the present invention with respect to the common polyethylene plug. Furthermore, the increase in stiffness and hardness of the polypropylene relative to the polyethylene can not affect the tightness and ease of opening of the plug according to the present invention, since the seal is provided by said protruding peripheral bead which alone is in contact with the inner wall of the neck. It follows that the contact surfaces between the plug and the same wall of the neck, although sufficient to ensure a high seal, are low and generate no significant friction, likely to oppose the separation of the cap from the neck.

 Optionally, for the sake of redundancy for the tightness of the plug according to the present invention, it is possible, on an inner face of said bottom between said outer side skirt and said inner skirt, rib or sealing lip adapted to be applied with sealing against the annular end face of said neck.

In addition, so that the friction between the threads of said plug of said neck is not too great and allows easy screwing and unscrewing, despite the relative stiffness and hardness of the constituent material of the plug according to the present invention, it is advantageous to threading said outer side skirt is discontinuous and subdivided into net segments, which are separated from each other and each of which extends over an arc at most equal to 190. This reduces the thread surfaces of the plug in contact with the thread of the neck.

Furthermore, especially in the case where the plug according to the present invention is obtained by forming in a mold, for example injection, it is advantageous that said outer side skirt has an external shoulder, adapted to serve as a catch ejector provided for ejecting said plug from said mold. Thus, it may be possible to overcome any friction occurring between the surfaces of the polypropylene plug and those of the mold, which may make it difficult to demold the plug.

In the case where the stopper according to the present invention comprises a tamperproof ring extending the edge of said outer side skirt opposite said bottom and connected to the rest thereof by a tear line of lesser mechanical strength, it is advantageous if said tamper-evident ring is constituted by the extreme annular portion of said edge and said tear line is formed by a discontinuous cutting line, made after demolding said plug.

It is thus conceivable that said mold can be extremely simplified with regard to the tamper-evident ring and the tear-off line that this simplification of the production of the latter and of the mold is made possible only because the material constituting the plug ( lypropylene) is sufficiently rigid and hard to allow easy realization of said discontinuous cutting line, for example by means of a wheel. It goes without saying that such a simplification is economically very advantageous with regard to the production of the mold.

In the latter case, in order to further facilitate the ejection of the out-of-mold, it is advantageous that said external shoulder adapted to serve said ejector being disposed on said external lateral skirt outside said extreme annular portion. said stopper comprises at least one additional external shoulder also adapted to act as an outlet for said ejector and disposed on said truncated annular portion. such an arrangement then makes it possible to reduce to a minimum the thickness of said extreme annular portion, without the risk of pulling it out during demolding.

 The present invention furthermore relates to a method for producing a one-piece cap of shell-shaped plastic material for sealing the neck of a container, such as a bottle, said shell comprising a bottom, the inner face is adapted to be applied against the annular end face of said neck; an outer lateral skirt, carried by the periphery of said bottom and able to surround said neck externally, the inner wall of said skirt, the external side carrying a thread capable of cooperating with a thread carried by the external wall of said neck to fix said stopper on said lot; and a tamper-evident ring extending the edge of said outer opposite skirt to said bottom and connected to the remainder thereof by a tear line of least mechanical strength, this process being remarkable in that said shell is made in one piece of polypropylene without a tamper evident ring or tear line; then - in that part of said outer side skirt opposite said bottom, forming a cutting line capable of forming said tear line and transforming the end annular portion of said edge of the outer side skirt tamper-evident ring .

The figures of the appended drawing will make it clear how the invention can be realized. In these figures, identical references designate similar elements.

The figure shows, in enlarged diametral section, an embodiment of the plug according to the present invention.

The figure shows, also in enlarged diametral section, the plug of Figure 1 mounted on the neck of a bottle.

The figure illustrates the cap of FIGS. 1 and 2 at the outlet of its injection mold, before making the tear line of the tamper-evident band.

The plug 1, shown in FIGS. 1 and 2, is made of polypropylene and comprises a shell 2, symmetrical about longitudinal axis X-X. The shell 2 is provided with a bottom 3 and a side skirt 4 peripherally bonded to the latter, as well as a tamper evident ring 5, which extends said lateral skirt 4 at its open end opposite the bottom 3 and which is connected to this side skirt by a tear line 6. internal face <B> 31 </ B> of the bottom 3 carries an internal cylindrical skirt projecting inside said shell 2, and a projecting annular seal having the shape of a rib or a lip, disposed between said cylindrical skirt 7 and said lateral skirt 4. The cylindrical skirt 7 is provided with a protruding lateral sealing bead 9, arranged facing the lateral skirt the internal wall of the side skirt 4, the cap 1 comprises discontinuous thread 1, consisting of thread sections 10A, separated from each other by interruptions 10B and each of which extends an arc at most equal to 190 about said axis XX.

tamperproof ring 5 carries an annular bead <B> 11 </ B>, protruding towards the inside of said cap.

plug 1 is intended to be mounted on the neck 12 of a container, said neck having an external thread 13 adapted to cooperate with the thread 10 and a projecting external annular ring 14.

When the cap 1 is mounted on the neck 12 (see Figure 2) - the thread 10 of the plug 1 is engaged with the thread 13 of the neck 12; the bead 11 of the tamper-evident ring 5 is hooked behind the annular lip 14 at the neck 12; - The cylindrical skirt 7 of the cap 1 is pressed inside the neck 12, only the bead 9 of said skirt rests with sealing against the inner wall <B> 1 </ B> 21 of said neck; and - the annular seal 8 is sealingly applied against the annular end face 15 of said neck 12.

When the stopper 1 is unscrewed for the first time, the tamperproof ring 5 is retained by the projecting annular ring 14, while the shell is pulled away from the neck 12, which causes the rupture of the tear line. 6 and the separation of said tamper-evident ring 5 from the remainder of said shell 2.

As illustrated in FIG. 3, in order to obtain the plug 1 and FIGS. 1 and 2, it is first possible to produce, for example by injection molding, a polypropylene shell 20 comprising all the elements 2 to 5 and 7 to 1 described above. , the reference 5 designating the extreme annu lar part of the edge of the outer skirt 4. The shell 20 has more (just like the shell 1 which will be issued) an outer shoulder, said placed on said outer side skirt 4 to the outside said extreme annular portion 5, and at least one additional outer shoulder 22 disposed on said end annular portion 5.

outer shoulders 21 and 22 are adapted to serve as a catch ejector 23, to output said shell 20 out of the mold (not shown) in which it is made.

Thus, as it leaves the mold, the shell 20, made of a single piece of polypropylene, has neither a tamper-evident ring nor a tear-off line. To achieve these, after demolding of the shell 20, is formed, by a cutting operation, in the outer side skirt part op posed at the bottom 3, the tear line 6, thus transforming the extreme annular portion 5 of the edge external side skirt 4 ring - violability.

As can be seen in FIG. 1, the tear line may comprise cut lines or slots 6 separated from each other by uncut segments 6B.

Claims (1)

<U> CLAIMS </ U> 1. Plug (1) in one piece of shell-shaped plastics material (2) for sealing the neck (12) of a container, such as a bottle, said shell having a bottom (3), whose inner face (3I) is adapted to be applied against the annular end face (15) of said neck (12); - outer side skirt (4), carried by the periphery of said bottom (3) and adapted to surround said neck (12) externally, the inner wall of said outer lateral skirt (4) carrying a thread (10) adapted to cooperate with a thread (13) carried by the outer wall of said neck (12) for fixing said plug on said neck (12); and an inner skirt (7), carried by said bottom (3) and coaxial with said outer lateral skirt (4), said inner skirt (7) being able to penetrate into neck (12) while ensuring a tight contact with the wall internal (1 of the latter, characterized - that it is made of polypropylene, and - that said inner skirt (7) comprises at least one ph phure bead (9) projecting towards said outer lateral skirt adapted to be applied with sealing against the inner wall (12I) of said neck (12) 2. Plug (1) according to claim 1, characterized in that the inner face (3I) of said bottom (3) comprises an annular vane (8) arranged between said outer side skirt (4) and said inner skirt (7) and able to seal against the annular end face (15) of said neck (12). one of claims 1 or 2, characterized in that the thread (10) of said outer lateral skirt (4) is disconti naked and subdivided into sections of net (10A), which are separated from each other (in 10B) and each of which extends over an arc at most equal to 90. 4. Stopper (1) according to one of claims 1 to 3, obtained by forming in a mold, characterized in that said outer side skirt has an outer shoulder (21), adapted to act as a catch ejector (23). said mold for ejecting said plug out of the latter after molding. 5. Stopper (1) according to one of claims 1 to 4, obtained by forming in a mold and having a tamper evident ring proton geant the edge of said outer side skirt opposite said bottom and connected rest of it by a tearing line of least resistance, characterized in that said tamperproof ring is constituted by the extreme annular ring (5) of said edge and in that said tear line (6) is formed by a discontinuous cut line , performed after demolding said plug. 6. Stopper (1) according to claims 4 and 5, characterized in that said outer shoulder (21) adapted to act as a plug ejector said (23) is disposed on said outer side skirt (4) outside said extreme annular portion (5). 7. Stopper (1) according to claim 6, characterized in that it comprises at least one additional outer shoulder (22) also adapted to act as a plug ejector said (23), and said rest on said extreme annular portion (5). ). 8. Process for producing the cap (1) of claim 5, characterized in that said shell is made in one piece of polypropylene without tamper-evident ring, or tear line; then - in that part of said outer lateral skirt (4) opposite said bottom (3) is formed, a cutting line (6) able to form said tear line and to transform the extreme annular portion of said edge of the outer side skirt in tamper-evident ring.