HK1033302B - Device for packaging a liquid to be dispensed drop by drop - Google Patents

Description

Liquid packaging device for dispensing liquids drop by drop

Technical Field

The present invention relates to the liquid packaging industry, and more particularly to the design and manufacture of containers integrated with stopper dispensers for packaging liquids to be dispensed drop by drop.

Such devices are involved in many fields of application, not only for packaging pharmaceutical or cosmetic products, but also for packaging of, for example, lubricants or some solutions used in the agro-food industry. The purpose of using such devices is primarily long-term storage with only small doses for slow use, with only as few drops of liquid formulation being squeezed out at a time.

Background

In general, the formulations stored in such containers should also be free of any contamination. This is the case, for example, with eye drops, which must be isolated from the ambient air and the bacteria therein. In practice, there are two means for storing such preparations, and these two means may be used together. Firstly, a bacteria-proof filter is arranged on a liquid drop extrusion channel, and secondly, a protective agent is added into the liquid preparation, and the protective agent is easy to separate and retain so as to enable the extruded preparation to be purified again.

In the prior art of the present invention, there are packaging devices for the drop-by-drop dispensing of liquids comprising a container whose internal volume can be varied by manually deforming the wall of the container, and a dispensing head comprising a purge member which is disposed in the path of the liquid which is expelled from the container under the effect of the pressure generated by the reduction in volume of the container.

Such a packaging device is described, for example, in french patent 2638428 of the present applicant. In this patent document it is seen that in the dispensing head, before the liquid discharge channel, there is a fine-meshed screen constrained by an upstream clarifier, downstream of which there is a filter, for example constituted by an anti-bacterial membrane, which separates the protective agent from the ophthalmic liquid to be dispensed.

However, the device of the known art described above still has a number of drawbacks, for which the present invention proposes a solution. In particular, when used for treating eye diseases, it is suitable for applying a liquid drop by drop to the eye of a patient, which is usually done by the patient himself and is therefore more delicate.

More generally, such devices do not achieve the desired accuracy in the dosage accuracy of the medicament. On the one hand, it is difficult to apply a slow and uniform squeezing force to the container repeatedly, for example, if the force is too fast when pressing the outer wall of the container, the medicament cannot be made to drop-by-drop, and more medicament is squeezed out at a time. On the other hand, the pressure exerted by the user may vary during use of the device. As the dose is consumed, the force increases gradually and, until the end of the dose bottle is used up, there is always a residual quantity of unused liquid in the container.

Disclosure of Invention

The invention therefore seeks to achieve a dispenser which can achieve as small and uniform a flow of liquid as desired to ensure the formation of droplets, while avoiding the influence of the operating conditions of the deformable wall of the container, so as to enable the dispenser to function practically as a dropper. The present invention also aims to achieve a more complete utilization of the liquid formulation initially filled into the container.

The present invention even enables control of the formation and discharge of individual droplets by means of features of various aspects of the invention, such as those defined and described below, which may be advantageous in industrial applications. In addition, the invention can improve the operation safety of the packaging device when the packaging device is used for other purposes, such as the pure state of the preparation, and the invention can also facilitate the industrial production and reduce the cost.

In order to achieve the objects of its various aspects, the invention proposes a device for packaging a liquid to be dispensed drop by drop, comprising a flexible-walled container which can be manually deformed towards a rigid neck in which a dispensing head is housed, the end of which is a discharge channel for the liquid outside the container, characterized in that it comprises a microporous plug inserted in the body of said dispensing head, crossing the section of the liquid channel between said container and said discharge channel, upstream of a liquid dispensing chamber between the downstream end face of said microporous plug and said discharge channel.

When the volume of the container is reduced, the resulting pressure pushes the liquid through the plug, which acts to create a controllably adjustable pressure differential on the liquid stream. The liquid dose that passes through the microporous plug with each squeeze of the container by the user is accumulated in the space of the microporous plug of the dispensing chamber before the drop is clearly expelled through the discharge channel. In this respect, the working effect of the device of the invention appears to be quite good when the volume of the dispensing chamber is sufficient to receive a dose of three drops.

A microporous stopper of the present invention having satisfactory results is preferably realized by a material inert to the liquid contained in the container. In particular, suitable materials are felts or foams having a high apparent porosity, such as, as is well known, resins made from various organic polymers. In the main application of the present invention, the microporous plug is preferably realized as a felt sheet of polyester or modified polyester resin, particularly, such as low-density polyethylene resin or polyethersulfone resin.

Resins of the kind mentioned or equivalent materials are known per se, and the benefit within the scope of the invention is that it is suitable to realize a microporous plug of cylindrical shape with a diameter of 0.5 to 3 cm and a length of between 0.2 and 1 cm, which has sufficient softness to sealingly mate with the preferably cylindrical body of the dispensing head, and which also provides microporous channels for the liquid in the length direction, the average diameter of which may be chosen between 0.3 and 10 microns.

The above size ranges are well suited to achieve the desired effect, especially in the case of aqueous solutions of drugs, such as eye drops for treating the cornea, or any other solution for dropwise application to the eye.

In fine-meshed screens, such as those mentioned in the prior art referred to in the french patent application with the applicant's publication No. 2638428, the microporous plugs of the device of the invention are designed and arranged so as to occupy the entire cross section of the fine-meshed screen and preferably occupy two thirds of the longitudinal height of the fine-meshed screen, the remaining third of this height being left to the distribution chamber.

It is also advantageous to incorporate a downstream filter element of the anti-bacterial membrane type into the microporous plug to protect the liquid in the container from contamination by the ambient air. Particularly suitable membranes currently have a thickness of a few tenths of a millimeter and an average size of the mesh between 0.2 and 0.8 microns. After being impregnated with the solution, the membrane prevents ambient air from penetrating into the container to displace the discharged liquid. It is therefore clear that the microporous plugs proposed by the present invention are completely different in this respect, as well as in structure and function.

In connection with the presence of a downstream filtering or purifying element, preferably constituted by an antibacterial membrane, as a second characteristic of the invention, the invention provides for said element to be coated on an end head connected to the body of the dispensing head in which the discharge channel is present. In practice it will be understood that the membrane is herein held flat between two platforms which are still perforated to avoid leaving droplets between the two steps of droplet dispensing to wet the membrane which would otherwise be detrimental to the function of the membrane.

As a preferred embodiment, such a platform may be realized by the material of the dispensing head, with star-shaped ribs forming a partition between the downstream surface of the microporous plug and the anti-bacterial membrane. In cooperation with the star-shaped ribs, the head preferably has a plurality of fan-shaped grooves, the fan-shaped circles being concentric circles around the central hole of the discharge passage.

In addition, the dispensing head constitutes an insert or "cell" in the neck of the container, possibly provided with a further purging element, upstream of the microporous plug, which purging element itself is in particular a conventional element for removing the protective agent from the discharged liquid, so that the protective agent remains in the container as required, for example in the case of eye drops. According to other embodiments of the device of the invention, said one and the same microporous plug may simultaneously have a plurality of functions as described above. This is particularly the case when the microporous plug has a cover layer or a suitable treatment layer upstream thereof.

In all cases, the regulation control of the flow of liquid pressed through the plug of the device according to the invention, by preventing excessive overpressure in the container itself, allows to create a pressure difference between the inside and outside of the container that is most suitable for the formation of droplets. However, also the distribution of liquid evenly across the pores in the cross-section of the liquid flow path before exiting the microporous plug to collect in the distribution chamber appears to contribute significantly to the beneficial effects of the invention.

Other features of the invention are directly related to the aforementioned ones, in that the improvement of the droplet formation conditions allows to better adapt the device assembly structure in various dimensions and volumes, according to practical requirements, thus facilitating low-cost manufacturing.

According to one mode of execution of the device according to the invention, the container wall has a cylindrical general outline, in the form of a deformable bellows, and is provided at the longitudinal ends with a transverse rigid bottom. Preferably realized in a castable material integral with a rigid neck portion mounting said dispensing head and an outer stiffening ring radially beyond the general contour of said bellows, so as to be gripped by automatic assembly machines without touching the more fragile wall of said bellows.

Preferably, such a bellows-type container is mounted by its neck inside an outer protective shell which protects most of the length of the container. Thus, the aforementioned external reinforcement ring is more useful for the operation of pushing the container with force in the casing during assembly, which is achieved by a tube abutting against the reinforcement ring.

When it is desired to enable the bellows-type container wall to be compressed over almost its entire length, it is highly desirable to have the protective shell of the bellows at least equal in length to the uncompressed length of the bellows, while providing a contact seam in the protective shell extending from the open bottom thereof.

However, the invention also makes use of the solution according to which the casing is cylindrical and continuous all around, to which a closing cap is attached, which fits on the casing in its extension, which is removable to allow access to the bottom of the container. This solution not only has the advantage of better protection of the flexible container, but also better facilitates the automated production of containers, including the application of labels on the cylindrical shell.

Drawings

The present invention now will be described more fully hereinafter within the scope of the preferred features and advantages of the invention. The description is made with reference to the accompanying drawings, in which:

figure 1 shows a device for packaging aqueous liquids according to the invention, in which the dispensing head is shown in section in the upper half;

figure 2a shows the components of the device in a head-down position of use, with its separate cover shown separately in figure 2 b;

figure 3 shows a variant embodiment of the device described previously, which differs in the configuration of the outer protective shell of the bellows-type container;

figure 4 schematically shows the main equipment of the assembly machine of the various components of the device when it is mass produced;

figure 5 shows the step of mounting the bellows in its housing during assembly using such a machine.

Detailed Description

The packaging device is particularly convenient for dispensing aqueous liquids drop by drop, and is particularly suitable for dispensing pharmaceutical solutions of aqueous media, such as eye drops which are intended to be dropped drop by drop into the eye.

The device comprises a liquid-containing container consisting of a container 1 open at the neck 5, an outer protective shell 8 surrounding the container, a dispensing head 2 whose body 3 forms a "cell" movable between two positions in the neck 5 of said container, and a head 4 closing the body 3 outside the container, which is drilled with a discharge channel 41. The entire assembly is covered by a removable lid 7.

The internal volume of the container 1 can be changed by deforming the wall of the container 1 by hand. It can be seen from the figures that in the main part of the longitudinal section along the axis of the device, the general profile of the wall, which is vertical in the position shown, is cylindrical, in the form of a bellows 12, which can be compressed by shortening its length. More precisely, as can be seen in particular in fig. 2, the user, by applying a force to the rigid bottom 13 of the bellows 12 for this purpose, pushes it with the fingers in the direction of the neck of the container and of the dispensing head connected thereto (generally with the index finger when holding the head of the container with the thumb and middle finger). The reduction in volume of the bellows thus caused is gradual, with a pause at each step of the dropwise dispensing of the liquid, if the device is equipped with means to prevent external air from entering the container to replace the discharged liquid.

In the preferred embodiment described herein, the last volume is maintained by a bacteriostatic membrane 9, fixed flat between two platform supports, transecting the entire passage section of the liquid in the body 3 of the dispensing head. The anti-bacterial membrane is also arranged such that it is never wetted by the liquid in the container outside the time of use of the drop-wise dispensed liquid. This helps to maintain the anti-bacterial activity of the anti-bacterial membrane and makes it impermeable to air throughout the storage period and the useful life of the container. Such films are per se conventional technology, with pores having an average dimension of, for example, 0.45 μm.

According to the invention, a microporous plug 6 is inserted in the body 3 of the dispensing head, between the reservoir 1 and the discharge channel 41, across the entire passage section of the liquid. The microporous plug is formed of a cylindrical rod of a neutral material that is chemically inert to any component of the liquid contained in the container to be dispensed, such as a protectant in an aqueous ophthalmic solution. More precisely, in the example described, the microporous stopper is an organic material based on polyethylene material, which has a certain flexibility so that it can be easily sealed into the dispensing head by being forcibly inserted into the body 3 of the dispensing head, provided that the body 3 has a cylindrical internal section of the same diameter without any clearance.

As can be seen in fig. 1, the microporous plug 6 does not extend in the longitudinal direction to the inner opening of the discharge channel 41. Instead, the plug is upstream of a chamber 31 formed in the cylindrical body 3 between a downstream end surface 63 of the plug and an end surface of the tip 4. The chamber thus has an expanded section with respect to the discharge channel 41, which in practice has at least the same extent as the section of the microporous plug 6, even slightly greater than that shown in figure 1. The chamber functions as a dispensing chamber for the liquid that passes through the microporous plug under the squeezing action of the user, provided that, as previously mentioned, its volume is sufficient to receive the liquid that has passed through the microporous plug 6 in an amount equivalent to a single dispensed dose.

In the particular embodiment described, the microporous plug 6 is allowed to occupy substantially two thirds of the longitudinal height of the body 3, which, starting from the first use of the device, is positioned in correspondence with the neck 5, the remaining part of the height being left for the distribution chamber 31 directly against the lower part of the tip 4, a hole being drilled in the centre of the tip 4 for the discharge channel 41. The average pore size of the microporous material is about 0.5 microns.

According to the above construction and arrangement, the microporous plug 6 operates such that, each time the volume of the container 1 is reduced by a force, the resulting pressure pushes the liquid through the plug, which creates a regular pressure differential across the flow of liquid therethrough. Thus, the microporous plug, together with the distribution chamber 31 which collects the distribution of the liquid towards the inlet of the channel 41, and with the operating mode of the bellows, ensures good results of the liquid distribution-in fact, drop by drop-by determining a discharge pressure difference. The discharge pressure differential is virtually no longer sensitive to the manner in which the user presses the bottom to compress the bellows, and more or less force may be applied to the bottom more or less quickly.

For containers for medicaments it is desirable to avoid any possibility of contamination of the medicament during storage before first use. For this reason, the device of the invention is designed to allow a hermetic seal to be obtained between the dispensing head and the interior of the bellows 12, which has the additional advantage of simultaneously preventing the flow of liquid towards the anti-bacterial membrane, regardless of the position of the container.

According to the embodiment shown in particular in fig. 1 and 3, the closure requires that the dispensing head be designed in combination with the neck of the container and that the removable cap 7 be fitted to the housing 8.

As shown in particular in fig. 1, the dispensing head 2 is mounted movably by its body 3 in a rigid neck 5 of the container, between two predetermined positions. In any one of these positions, the mounting of the body 3 in the neck 5 remains sealed, by virtue of the fact that it has, on its outer periphery, three annular projections 32 which engage elastically in corresponding annular grooves, longitudinally successive grooves, on the inner surface of the neck 5.

Before the first use, the dispensing head is in a safe, so-called high position as shown in fig. 3, with two of the annular projections 32 in two grooves of the neck 5 and the third (upper) annular projection reaching only the end of the neck 5. In this position, a lower cap 33 carried by the body 3 is in sealing contact with the inner surface of the neck along a frustoconical surface forming a bearing surface 52 around the axis of the device. Thus, the cap 33 sealingly closes the inner space of the container 1, and the liquid contained in the container cannot flow to the microporous plug 6.

Conversely, when the dispensing head is pushed down to the position shown in fig. 1, referred to herein as the usable position, cap 33 is positioned to move to a portion 51 of the rigid neck where the inner diameter is larger. In this position, communication between the bellows 12 and the dispensing head is obtained by means of the inclination of the holes 34 of the valves, each occupying approximately one third of the section of the body 3, located at the three fins connecting the cap 33 to the body. In this way, the liquid contained in the bellows 12 can freely pass through the upstream surface 62 of the microporous plug 6 to the dispensing chamber 31, provided that the bellows 12 is slightly manipulated by the user to create an overpressure in the container 1. In this position, the seal is still maintained around the body 3, since the two upper annular projections 32 are lodged in the grooves of the neck 5, while the third (here lower) annular projection rests against an internal shoulder 53 of the neck.

The movement of the dispensing head from the safety position to the usable position between two different longitudinal positions inside the neck 5 is obtained by forcing the cap 7 covering the device assembly at the first use.

The design of the lid 7 is shown in fig. 1 and 3. Seen from the inside, as a means of engagement in any case with the head 4, said cover has a central pin 71 which gently catches in the flared end of the channel 41, an annular ring 72 which guides the cover centrally on the outer surface of the conical extension 43 of the seat 42 of the head 4, through which the channel 41 passes axially, and another annular ring 73 of greater diameter which bears against the outer surface of the head seat 42, which is the upper flat surface of the head seat.

The lid 7 can be unscrewed. However, it is not screwed directly onto the neck 5 of the container, but onto the aforesaid housing 8. All parts of the housing are rigid. In addition to a body portion 81 forming a jacket around the bellows 12, the housing extends with a neck portion which is fixedly mounted on the neck portion 5 of the container. As can be seen from fig. 1, to ensure the sealing requirements, the neck 82 and the neck 5 have complementary surfaces for this purpose, which have shoulders or projections thereon, which can be tightly engaged by a resilient clamping action.

On its outer surface, the neck of the housing 8 is formed with a helical thread 84, with which a corresponding thread on the inner surface of the cap 7 cooperates. The lid 7 is produced with an indestructible ring 74 which prevents the lid from being screwed over beyond the safety position shown in figure 3 in which the closure 33 sealingly contacts the corresponding inner wall (bearing surface 52) of the container to close the compressible inner space of the container.

When the user removes the non-breakable ring 74, the lid 7 can be screwed into the position of use, in which it rests against an upper shoulder 83 of the housing 81. During its longitudinal displacement, the lid 7 carries the dispensing head 2, pressing it into the container until the hole 34 is opened. Later, the cap can be screwed on and off each time a preparation is dispensed, without the dispensing head being moved thereby. Here, it is to be noted that the housing 8 and the cover 7 preferably have the same outer diameter, not only for the purpose of improving the aesthetic appearance, but also for the purpose of facilitating automated production thereof.

Turning now to the configuration of the dispensing head 2. In fig. 1 it can be seen that when the tip 4 is not yet fitted, the microporous plug 6 is inserted into the body 3 of the dispensing head 2 during assembly from the upper opening of the internal cylindrical channel (with smooth surface) until it comes to rest, if necessary, on an internal shoulder 35.

At its upper end (in the position shown in figures 1 and 2), the body 3 is formed with an external flange 36 which abuts against the upper ends of the neck 5 of the container and the neck 82 of the shell when the dispensing head is brought from the safety position to the usable position on first use. It is on this flange 36 that the head 4 is mounted, preferably by simple gluing. On the inside, moreover, the same flange is formed to receive a structure 38, which is cast integrally with the flange in the material of the body of said "cell" 3, one of the functions of which is to block the microporous plug 6 by its downstream surface 63.

Again, however, the formation 38 with the large star-shaped aperture serves to form a partition between the microporous plug 6 and the base 42 of the tip 4. In this way it leaves a space for the distribution chamber 31, which is defined by the flared walls of the structure between the radial ribs connecting the cylindrical central portions.

In addition, this structure also serves to hold and support the antibacterial film 9 by its periphery and the edges of its ribs. It can therefore be said that this structure constitutes a support platform for the film, which is applied against the lower surface of the base 42 of the tip 4, the latter forming another platform. In the base of the tip, and therefore on the other side of the membrane, annular grooves 44 are provided to avoid continuous contact with the membrane 9. In this way it is ensured that the film mounted between the two support platforms is not wetted by the solution between two successive dispenses, despite the surface tension effects.

The figures show two different embodiments in terms of the design of the housing 8, but the same in terms of cooperation with the other components of the device as shown in fig. 1.

The first of these two embodiments is shown in figure 2a, which shows the device in the dispensing position, head down, with the lid 7 (figure 2b) having been removed by the user. In this case, the housing 8 encases the bellows 12 over its entire length before use. The housing, on the other hand, has no bottom and has a longitudinal slit 85.

For drop-wise dispensing of the liquid, the user slides his finger along the longitudinal slit through the open bottom 81 of the housing 8 to reach the bottom 13 of the bellows. As the container is emptied, the finger can always touch it sufficiently through the longitudinal slit 85, causing it to compress longitudinally until only an unavoidable residual amount remains therein.

The benefit of the second embodiment is that the function of the microporous plug 6 can be better utilized. Access to the rigid bottom of the bellows is still achieved through the open bottom of the housing 8. But the housing of this embodiment does not have a longitudinal slit. It is thus a continuous cylindrical shape around its circumference, which makes its manufacture more convenient, since it is easy to apply the label to the upper side in an industrial production line. The housing 8 is thus also connected to a closure cap 87 which serves to close the bottom of the housing surrounding the bellows, but which, of course, can also be removed.

It goes without saying that the housing 8, apart from the possible closing cap 87, is preferably realized in one piece in plastic by die-casting (using known injection-molding techniques). The same is true for the container 1. It is realised in the same material, with walls of different thickness, ensuring on the one hand the rigidity of the neck 5 and the bottom 13, and on the other hand sufficient flexibility of the rest of the container to allow it to form a flexible bellows 12 after the forming operation.

However, the container 1 has an unusual feature. It has an external lobe 55 at the base of the neck 5, forming a ring which is also rigid, thus forming a reinforcing ring whose outer periphery exceeds the profile of the bellows 12, forming an annular plane. Its use relates to the assembly process of the components of the invention, as will be briefly described below with reference to fig. 4 and 5, without specifically describing the mechanisms of the production plant, which are of no particular nature in their construction, interrelation and function in the field of automated industrial plants.

According to the said figure, the apparatus comprises a central assembly of circular conveyors, in which a horizontal platform 101 is mounted in rotation, with four identical sockets in sequence, in front of four devices placed around its periphery. In figure 4 it can be seen that the four surrounding devices comprise three feeding devices 102, 103, 104, each of which is known to consist of a vibrating hemispherical container which receives the parts to be assembled from a hopper 105, passing them one by one through a chute, so as to be correctly oriented for gripping by a transport system indicated by the reference numeral 107. At the fourth device, the assembly work of the packaging device of the present invention in the socket is completed; the device is then transferred away and collected in a qualified bin 122, and the detected rejects are sent to a reject bin 123.

According to a determined solution of the invention, during the manufacture of the device, each of the feeding devices successively reaches the respective assembly position, first the housing 8 (which is visible in fig. 5 fixed in the socket 121 and here of the slotted 85 type), then the container 1 and finally the bottom head 87, closing the housing in fig. 3. In another alternative, another part, such as a lid 7 (which is then located on the other side of the rotary platform), a head 4, or a package, may be mounted at the third feeder or at another device added to the rotary platform.

Fig. 5 shows the device in a second feed position, which corresponds to the handling of containers during assembly. This figure is intended to illustrate the use of the reinforcement ring 55 of the device of the present invention.

In particular, it can be seen that the container 1 is operated head down in the figure, while its bellows is protected by a tube 112 which is part of the equipment of the transfer system. On the contrary, in view of making the illustration, which is simplified in itself, easy to read, the case of filling the container with the liquid to be dispensed at this stage and of fitting the "cells" with the microporous plug 6 is not shown, i.e. the body 3 of the dispensing head is not closed by the tip 4, which is then applied against the body 3.

The benefits of the described design of the device of the present invention are described below. Due to the use of a microporous plug, the body 3 constitutes an effective valve of the container when the rigid bottom 13 is not compressed to reduce its internal volume and thus create an overpressure with respect to the outside. The seal is achieved solely by the microporous plug which extends out of the rigid neck of the container. The tightness is achieved by means of elastic compressibility around the microporous plug. The microporous plug thus allows, together with the external stiffening ring 55 of the neck, the operation of the container head-down on the assembly machine. This also makes it possible to control its position in the dispensing head to a safe position, without reaching the use position.

In fact, the container 1 is transferred to this position, being suspended by the suction of the vacuum cup on its rigid bottom, until it is placed on top of the casing 8 already in the socket 121. The bellows of the container is not deformed during the whole time the container is being worked in this position, since the lower end of the tube 112 bears against the reinforcement ring 55, and more precisely against the rear surface of the container beyond the bellows. Also by the mechanical action of the pressure exerted on the reinforcing ring by the tube 112 (which is inserted in the casing 8, leaving a gap), the container is pushed to press its rigid neck 5 into the mouth of the casing 8, which does not touch the "cell" 3 in the safe position.

The same reinforcement ring 55 can be used in the opposite direction to secure the container by means of a suitable gripping tool when the "cell" is pressed into a safe position in the neck of the container.

The foregoing description is intended to be illustrative, exemplary and not restrictive in character. Obviously, many modifications and variations are possible without departing from the scope of the invention.

In particular, it is not mentioned above that the cover 33 is recessed towards the axis of the device, although this is clearly visible in the figures. This feature improves the process of liquid flow towards the microporous plug 6.

In addition, in the same position, three ribs supporting the hood (between the holes 34 of the liquid channel) may receive, at their upper edge (fig. 1), and therefore just downstream of the microporous plug 6, a selective filter for certain components of the liquid that should not be contained in the discharged drops. This is the case, for example, for aqueous ophthalmic solutions containing a protective agent which is held back by adsorption by a filter or purification membrane. It is noted, however, that in general, depending on the material used for the microporous plug and the dimensions of its pores, the presence of a microporous plug is sufficient to achieve the desired effect. It is also conceivable to carry out some suitable treatment of the microporous plug by applying some known technique, especially when the microporous plug consists of a non-woven fibrous felt having a density corresponding to that of low-density polyethylene.

Finally, as can be seen in figure 1, the base 42 of the tip 4 has an edge forming a small groove in which the membrane 9 is housed. In this way, the membrane is protected from damage by mechanical factors until the tip is fitted to the body 3, which has a shape complementary to the shape of the edge at the periphery of said formation 38.

Claims (16)

1. Liquid packaging device for the drop-by-drop dispensing of a liquid, comprising a flexible-walled container (1) which can be deformed manually towards a rigid neck (5) in which a dispensing head (2) is sealingly mounted, which ends in a discharge channel (41) outside the liquid discharge container, characterized in that it comprises a microporous plug inserted in the body (3) of the dispensing head, crossing the liquid passage section between the container (1) and the discharge channel (41), upstream of a liquid dispensing chamber (31) with an expanded section, in the body (3), between the downstream end face (63) of the microporous plug (6) and the discharge channel (41), the microporous plug (6) being realized in a material inert to the liquid, the pressure generated when each time the volume of the container (1) is reduced by force pushes the liquid through the plug, which creates a regular pressure difference to the flow of liquid therethrough, the volume of the dispensing chamber (31) being sufficient to contain the liquid passing through the plug (6), the container precluding any possibility of air entering to displace the discharged liquid.

2. Device according to claim 1, characterized in that said container (1) is constituted by a wall of generally cylindrical outline, in the form of a longitudinally deformable bellows (12) ending in a rigid transverse bottom (13).

3. The device according to claim 2, characterized in that said bellows (12) is realized in a single piece of castable material with said rigid neck (5) mounting said dispensing head (2) and with an external stiffening ring (52) radially beyond the general profile of said bellows (12), so that it can be gripped by automatic assembly machines without touching the more fragile wall of said bellows.

4. A device according to claim 1, characterized in that it has a downstream filter element constituted by a bacteria-tight membrane (9) arranged between said microporous plug (6) and said channel (41), crossing said distribution chamber (31), effective to exclude any possibility of air entering said container to replace the discharged liquid when said membrane is impregnated with said liquid.

5. Device according to claim 1, characterized in that the body (3) of the dispensing head (2) is movably mounted inside the neck (5) between two different longitudinal positions, comprising a safety position in which the communication between the container (1) and the passage (41) through the microporous plug (6) is hermetically closed, and a usable position in which the passage through the dispensing chamber (31) to the upstream surface (62) of the microporous plug (6) is open.

6. Device according to claim 1, characterized in that the body (3) of the dispensing head (2) sealingly mounted in the rigid neck (5) is shaped as a cylindrical tube, the entire internal cross-section of which is occupied by the microporous plug for two thirds of its length, the remaining third being left for the dispensing chamber (31).

7. Device according to claim 1, characterized in that said microporous plug (6) is made of a material based on an organic resin, which is slightly flexible so that it can be inserted with force into the body (3) of said dispensing head so as to seal it therein.

8. The device according to claim 7, characterized in that the material of the microporous plug (6) is a foam of high apparent porosity, or an equivalent felt, in which the open micropores for the passage of the liquid have an average pore size of between 0.3 and 10 microns.

9. The device according to claim 1, comprising a downstream filtering element comprising an anti-bacterial membrane, characterized in that said membrane is flatly sandwiched between two perforated platforms, each constituted by a body (3) of said dispensing head downstream of said dispensing chamber (31) and by an end head (4), said end head (4) being connected to said body (3) and through which said discharge channel (41) is arranged.

10. Device according to claim 2, characterized in that the container (1) is mounted by means of the neck (5) inside an outer protective shell (8) which encloses a major part of the length of the container.

11. Device according to claim 10, characterized in that said casing (8) is cylindrical and continuous all around, with a closing cap (87) attached thereto, which fits on said casing in the extension thereof, said extension being removable to allow access to the bottom (13) of said container (1).

12. The device according to claim 10, characterized in that said housing (8) extends over the entire length of said container (1) and has a longitudinal slit (85) providing a passage for longitudinally compressing said bellows (12) from the open bottom (81) of the container.

13. The device according to claim 2, having a downstream filtering element comprising an anti-bacterial membrane, characterized in that said membrane is flatly sandwiched between two perforated platforms, each constituted by a body (3) of said dispensing head downstream of said dispensing chamber (31) and by an end head (4), said end head (4) being connected to said body (3) and through which said discharge channel (41) is arranged.

14. Device according to claim 2, characterized in that the body (3) of the dispensing head (2) sealingly mounted in the rigid neck (5) is shaped as a cylindrical tube, the entire internal cross-section of which is occupied by the microporous plug for two thirds of its length, the remaining third being left for the dispensing chamber (31).

15. The device according to claim 14, characterized in that the material of the microporous plug (6) is a foam of high apparent porosity, or an equivalent felt, in which the open micropores for the passage of the liquid have an average pore size of between 0.3 and 10 microns.

16. The device according to claim 15, comprising a downstream filtering element comprising an anti-bacterial membrane, characterized in that said membrane is flatly sandwiched between two perforated platforms, each constituted by a body (3) of said dispensing head downstream of said dispensing chamber (31) and by an end head (4), said end head (4) being connected to said body (3) and through which said discharge channel (41) is arranged.