EP3148787A1

EP3148787A1 - Multi-layer tablet with recess, device and method for compacting such a tablet

Info

Publication number: EP3148787A1
Application number: EP15725613.2A
Authority: EP
Inventors: Jacques Brosse; Valérie VENET; Jean-Louis ESPEIT; David MALARTRE
Original assignee: Eurotab SA
Current assignee: Eurotab Operations SAS
Priority date: 2014-05-28
Filing date: 2015-05-27
Publication date: 2017-04-05
Also published as: FR3021666B1; US20190337254A1; WO2015181241A1; US10828856B2; US10293566B2; CA2950471A1; FR3021666A1; US20170197375A1; AU2015265951B2; AU2015265951A1

Abstract

The invention relates to a press device for manufacturing compacted tablets from at least one mixture in powder form, comprising at least one compaction assembly comprising a lower punch (3) and an upper punch (4) each having an active compaction surface and placed on either side of a die, in which the lower punch has a longitudinal recess open on the side of the die, inside of which is mounted a central rod which is translatably mobile relative to the lower punch, characterised in that the central rod is coupled to the lower punch by means of a resilient link provided so as to hold, in an inoperative position, the central rod in a maximum deployed position in which the central rod protrudes relative to the active surface of the lower punch. The invention also relates to a specific compaction method and to a multi-layer compacted tablet with a recess.

Description

Multilayer cavity tablet,

device and method of compaction of such a tablet

FIELD OF THE INVENTION

The present invention relates to multilayer tablets having a cavity, as well as a rotary press for forming such a tablet and an associated manufacturing method. The proposed invention may for example be useful in the field of the manufacture of disinfectant tablets, for the purification of water for example, or detergent tablets, intended to be used in devices such as dishwashers or washing machines for the cleaning items of dishes or laundry respectively.

STATE OF THE ART

The detergent tablets are most often prepared by mixing various components, preferably in the form of powder or granules, but also in liquid form. This mixture is then compacted using a press to form a tablet. Nevertheless in the detergent tablets, some components do not support compression, others may react before use and thus reduce the effectiveness of the tablet during use, that is why multilayer tablets have been developed as described in the patent application EP0979862. In fact, the multilayer tablets make it possible both to separate the ingredients that can react and to compress the ingredients sensitive to compression only once by inserting them into the last layer for example. Multilayer tablets may exhibit slightly delayed disintegrations between different layers, the first layer having been compressed several times generally has a longer disintegration than the subsequent less compressed layers.

It has also been developed other formats of tablets such as tablets called "tab tab" formed of a conventional single layer or multilayer tablet on which is positioned a portion of tablet, in the form of a half sphere for example. The "tab on tab" format separates incompatible compounds in different layers while improving the appearance of tablets. This tablet format also allows for a sequenced disintegration of the different phases of the tablet. Such tablets and related manufacturing methods are for example described in WO01 / 98448, WO01 / 49815, EP1 179042 and EP1244767.

The application WO2006 / 048606 describes a method of manufacturing a multilayer tablet having a cavity for receiving an insert such as a ball, the cavity being formed with a method of compaction by stamping. More precisely stamping compaction provides, in a rotary punch press for example, an upper punch comprising an active compaction surface having a profile with a protruding portion so as to form the cavity in the various compacted layers. With such a compaction process, the areas below and adjacent the sides of the cavity are compressed to a much greater degree than the rest of the tablet which creates density heterogeneities within the tablet. Such heterogeneities of density have the consequence that the different zones of a layer have different disintegration and solubilization profiles, and this also affects the mechanical strength of the tablets.

In order to remedy these drawbacks, it has been proposed in the application

WO00 / 10800 to use a press device where the lower and upper punches each comprise an annular portion and a central portion, movable independently of each other. Such a press device can form multilayer tablets where one of the layers has the shape of a ring, while the layer immediately adjacent to this annular layer covers and even completely fill the central cavity of the annular layer. Such a tablet has the advantage of having relatively homogeneous mechanical properties, especially in terms of density, and it is visually close to a tab-on insert tablet which has a certain commercial interest. However, the proposed manufacturing process is complex to implement since it imposes independent control of the various parts forming the lower and upper punches. In addition, tablets formed by such a process have a number of disadvantages in terms of disintegration in particular. The application EP1440790 also describes a press device of this type, which makes tablets of very different shapes, but whose arrangement and operation are very complex.

Another method has been described in the application WO01 / 85437 which proposes to simplify the process described above by using a conventional upper punch and a lower punch comprising an annular part able to be displaced in translation, and a coaxial central element inside of the annular portion of the lower punch, the central member being maintained throughout the compaction cycle - particularly during the actual compression - in a determined fixed position where said central element is in the matrix beneath the upper surface of the die. The described method makes it possible to form shelves with a cavity, without the central rod being displaced during the various stages of the compaction cycle. Tablets which are formed with such a process may comprise several layers, where one of the end layers comprises a blind cavity inside which may for example be inserted an insert to form a tablet of the type "tab on tab ". Tablets as well formed have the advantage of having relatively homogeneous mechanical properties, especially in terms of density, and make it possible to make tablets of the "tab on tab" type. However, the functional properties of such tablets still have to be improved, especially in terms of disintegration.

An object of the present invention is therefore to provide a multilayer compacted tablet with cavity which does not have the aforementioned drawbacks.

In particular, an object of the present invention is to provide a multilayer compacted tablet with cavity which has increased functional properties, especially in terms of disintegration.

An object of the present invention is also to provide a multilayer compacted tablet with cavity which has improved mechanical properties, having for example a homogeneous density distribution, and having a mechanical strength for good handling and storage of the tablet.

Another object of the present invention is to provide an improved punched rotary press which makes it possible to form compacted compacted cavity tablets in a simple manner on an industrial scale.

Yet another object of the present invention is to provide a rotary punch press whose specific functional elements can be easily adapted to a traditional rotary punch press.

Another object of the present invention is to provide a method of manufacturing a compacted multilayer tablet with cavity which is simple to implement, not requiring in particular any control or specific control different from a manufacturing method of a multilayer compacted tablet having no cavity. SUMMARY OF THE INVENTION

For this purpose, a press device is proposed for making compacted tablets from at least one powder-form mixture, comprising:

a rotary plate in which is provided at least one matrix intended to receive the mixture,

at least one compaction assembly comprising a lower punch and an upper punch each having an active surface for compaction, said lower and upper punches being arranged on either side of the plate with their respective active surface opposite the matrix, and being movable in translation coaxially with the die and following the rotary movement of the plate, - wherein the lower punch comprises a longitudinal cavity open on the die side, inside which is mounted a central rod movable in translation by relative to the lower punch along a translation axis, characterized in that the central rod is coupled to the lower punch via a resilient connection provided along the axis of translation of the central rod to maintain, in the rest position, the central rod in a deployed position in which the central rod protrudes from the active surface of the lower punch.

This deployed position preferably corresponds to the maximum deployed position, that is to say the position of the central rod in abutment with respect to its translational movement towards the outside of the lower punch.

Preferred but non-limiting aspects of this device, taken alone or in combination, are the following:

the upper punch has a full plane or curved active surface,

the central rod is secured to the lower punch so that in the absence of stress applied to the central rod, said central rod remains in a fixed position relative to the lower punch during a movement of said lower punch.

the elastic connection has a restoring constant provided for the central rod to move inwardly of the longitudinal cavity of the lower punch as a result of a stress exerted from the upper punch on approaching said upper punch with respect to the lower punch.

- The elastic connection has a sufficient return constant so that the central rod remains at least partially projecting with respect to the active surface of the lower punch when bringing the upper punch closer to the lower punch.

the elastic connection has a stiffness constant of between 0.1 daN / mm and 10 daN / mm, preferably between 0.2 daN / mm and 4 daN / mm, preferably between 0.5 daN / mm and 3 daN / mm, and preferably still between 1 daN / mm and 2.5 daN / mm.

the device comprises a resilient connecting member interposed between the central rod and the lower punch to form the elastic connection, the elastic connecting member is preferably selected from a spring, an elastic compression rod, or a pneumatic cylinder.

the device comprises an actuating member fixedly mounted on the central rod and extending radially with respect to said central rod, said actuating member projecting laterally with respect to the lower punch through a groove in said lower punch, said actuating member being provided to abut against the die in order to position the central rod in a retracted position in which the central rod does not protrude from the active surface of the lower punch.

There is also provided a method of manufacturing a multilayer compacted tablet with cavity using such a press device.

In particular, there is provided a method of manufacturing a compacted tablet having at least two layers with a press device as presented, comprising the following successive steps:

E1. Drawing a first mixture in the form of powder and placing said first mixture in an open space formed by the lower punch and the die, so as to cover the active surface of said lower punch and the central rod projecting from said surface active;

E2. Approximation of the upper punch relative to the lower punch so as to exert a compaction stress on the first mixture to form a first compacted layer, said compaction stress further allowing a displacement of the central rod towards the interior of the longitudinal cavity ; E3. Distancing the upper punch from the lower punch so as to eliminate the compaction stress on the first mixture so that the central rod resumes its extended position relative to the lower punch, the central rod thereby piercing the first layer so as to form a through cavity;

E4. Collecting a second mixture in powder form and placing said second mixture in the open space formed by the lower punch and the die, so as to cover the first layer;

E5. Approximation of the upper punch relative to the lower punch so as to exert compaction stress on the second mixture and the first layer to form a second compacted layer on the first layer;

E6. Distance of the upper punch relative to the lower punch so as to eliminate the compaction stress on the compacted assembly formed by the first and second layers;

El. Ejection of the compacted assembly out of the matrix by a translation of the lower punch so as to flush the active surface of said lower punch with the surface of the turntable, the compacted assembly thus ejected forming the compacted tablet. Preferred but non-limiting aspects of this process, taken alone or in combination, are as follows:

during the ejection step E1, the movement of the lower punch towards the die moves the central rod into a retracted position in which the central rod does not protrude from the active surface of the lower punch.

before the ejection step E1, the successive steps E4, E5 and E6 are repeated as many times as it is desired to add additional layers to the compacted assembly.

before the ejection step E1, an additional compaction step is carried out by bringing the upper punch closer to the lower punch so as to exert an additional compaction stress on the compacted assembly.

Finally, there is provided a multilayer compacted tablet, where each layer is formed from a mixture in powder form, comprising:

a first layer with a through cavity along a longitudinal axis orthogonal to the first layer; and

at least one second layer formed directly on the first layer;

characterized in that the second layer fills less than 70% of the volume of the cavity of the first layer.

By construction, the first layer is the only pierced layer of the tablet.

Preferred but nonlimiting aspects of this tablet, taken alone or in combination, are as follows:

the second layer has a surface flush with the surface of the first layer without the second layer extending into the cavity of the first layer, the tablet has a compaction rate of the compacted powder mixture at the cavity different from the rate compaction of the multilayer tablet complete less than 5%, preferably less than 3%, and more preferably less than 1%.

the different layers are formed from powder mixtures for a detergent or disinfectant action.

DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent from the description which follows, which is purely illustrative and nonlimiting and should be read with reference to the accompanying drawings, in which: Figure 1 is a three-dimensional representation in section of a rotary press device;

Figure 2 is a diagram illustrating the rotational drive punches in the rotary press device;

Figures 3a and 3b are sectional views of the lower punch according to the invention, in the deployed position and in the retracted position respectively;

Figures 4a and 4b are detailed sectional views of the lower punch of Figures 3a and 3b in the deployed position and retracted position respectively;

Figures 5a and 5b are perspective views of the lower punch of the figures

4a and 4b in the deployed position and in the retracted position respectively;

The series of FIGS. 6 and 6a to 61 illustrate the different steps of the compaction cycle to form a compacted multilayer tablet with cavity according to the invention;

Figure 7a is a perspective view of a compacted multilayer tablet with cavity according to the invention;

Figure 7b is a perspective sectional view of the tablet shown in Figure 7a.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 is a perspective sectional view of a rotary press device which illustrates the structure conventionally used to drive the compaction punches in a rotary motion.

The rotary press device comprises a turret which is rotated by a known drive system via a drive shaft, which is generally central. The turret comprises a central plate 1 which comprises at least one compaction matrix 2, this matrix 2 being intended to receive a mixture of compounds, in powder form, from which it is desired to form a compacted tablet at a determined volume.

The central plate preferably comprises a plurality of matrices 2 distributed for example at the periphery of the central plate 1 which has a substantially circular shape.

Said matrices 2 have a generally cylindrical shape and are either formed by a through hole directly formed at the periphery of the central plate 1, or each die is a specific part comprising a central cylindrical through opening having a circular section with a determined diameter corresponding to the diameter. sought for the tablet, this piece serving as a matrix having an external shape adapted to be inserted into through openings formed at the periphery of the central plate 1. The press device further comprises compaction assemblies each formed of a pair of punches (not shown in FIG. 1), namely a lower punch and an upper punch, which are arranged on either side of each of the dies 2 of the central plateau 1. Preferably, the device comprises a lower pair of punches 3 and upper 4 for each of the matrices 2 of the device. The lower and upper punches 4 are mounted in the press so as to be axially movable relative to the corresponding die 2, so that said lower and upper punches 4 can be inserted into the die 2 to compress the powder mixture disposed. inside the matrix to form a tablet at a determined volume.

The lower 3 and upper 4 punches are also mounted in the press so as to have a circular movement corresponding to the circular movement of the matrix 2 with which they are associated. A solution for moving the punches along this circular path is to use drive plates 5 and 6 located on either side of the central plate 1, these two drive plates 5 and 6 being integral with the central plate. 1 and thus being also rotatably mounted in the press. The drive plates 5 and 6 are provided with through openings disposed at their periphery, these through openings being intended to receive the lower punches 3 and upper 4 respectively. The lower and upper punches 4 are thus rotated by the drive plates 5 and 6, respectively, synchronously with the corresponding die 2, the lower and upper punches 4 being able to slide further into the openings provided at the periphery. drive trays 5 and 6 so that the compactive active surfaces 32 and 42 at the compaction end of the lower and upper punches 3 respectively 4 can be inserted into the die 2.

The axial displacement of the lower 3 and upper 4 punches is controlled by lower control means and upper control means respectively, these lower and upper control means being intended to cooperate with the guide ends 31 and 41 of the lower punches 3 and higher 4 respectively. The control means are intended to move the corresponding punches along the axis of the die so as to modify the axial position of the punch (and more particularly the axial position of the compaction end of the punch) as a function of the operating cycle of the press. The axial position of a punch is defined as the position of the punch in the axis of the die, this position thus making it possible to characterize the axial displacement of the punch, but also the associated confinement volume. The lower and upper control means comprise all known elements for moving the lower and upper punches, such as for example cam paths and / or compacting rollers. These different elements are chosen and assembled according to the compaction cycle specifically required to form the desired tablet.

As illustrated in FIGS. 3a, 3b, 4a, 4b, 5a, and 5b, the proposed press device comprises the particularity of having a lower punch 3 having a main body 33 comprising a longitudinal cavity 34 open on the die side 2 on the active surface side 32. A central rod 35 is mounted inside this longitudinal cavity 34 so as to be movable in translation relative to the lower punch 3. The sliding central rod 35 is also called sliding finger.

As illustrated in FIGS. 3a and 3b, the main body 33 of the lower punch 3 is generally mounted on a punch holder forming the guide end 31 of said lower punch 3.

The central rod 35 is advantageously coupled to the lower punch 3 by means of an elastic connection 36 provided along the axis of translation of the central rod 35 in the longitudinal cavity 34.

The elastic connection 36 is provided to maintain, in the rest position, the central rod 35 in an extended position in which the central rod 35 protrudes with respect to the active surface 32 of the lower punch 3. As illustrated in FIGS. 4a, and 5a, this deployed position is the maximum deployed position, that is to say that the central rod 35 can not slide further towards the outside of the body of the lower punch 3. Indeed, the arrangement of the Central rod 35 is for example provided so that this central rod comes into abutment against an inner wall of the body 33 of the lower punch 3 thus limiting its translation outwards, and thus defining the maximum deployed position.

The central rod 35 is preferably integral with the lower punch 3 so that in the absence of stress applied to the central rod 35, said central rod 35 remains in a fixed position relative to the lower punch 3 during a movement of said lower punch 3.

Thus, except that a specific stress is applied to the central rod 35, the movements of said central rod 35 are highly dependent on the movements of the body 33 of the lower punch 3.

Preferably, the central rod has a passive displacement, that is to say it is the movement of other parts of the press device that will cause the displacement of the central rod 35, in particular the movement of the lower punch. 3 and / or upper punch 4. The specific arrangement proposed makes it possible to move the central rod 35, and possibly modify its positioning relative to the body 33 of the lower punch 3, without direct actuation of said central rod 35. In fact, it is mainly the movement of the upper punch 4 relative to the lower punch 4 which makes it possible to move the central rod 35 relative to the body 33 of the lower punch 3. It should be noted that the upper punch 4 may have a conventional shape, in particular with a simple active surface, that is, that is to say without cavity or protuberance, but on the contrary a solid surface. Thus, the upper punch 4 has a flat active surface or a curved surface if it is desired that the outer surface of the tablet to be formed is curved, but in all cases the surface is full.

The displacement of the central rod 35 relative to the body 33 of the punch 3 is dependent on the elastic connection 36 between these parts.

The elastic connection 36 may for example be formed by an elastic connecting member 36 interposed between the central rod 35 and the lower punch 3.

Such an elastic connecting member 36 may for example be a spring as illustrated in the various figures. This spring is preferably a compression spring extending from one end of the central rod 35 into the longitudinal cavity 34 and bearing on an inner wall of the body 33 of the lower punch 3.

The elastic connection member could however be any other element to ensure the function required for the elastic connection. Thus, one could consider the use of an elastic compression rod. It could also be used a pneumatic cylinder.

According to a preferred embodiment, the elastic connection is provided by the use of Belleville washers. Belleville washers are washers that have a specific shape to ensure a spring function.

Preferably, the elastic connection 36 has a restoring constant provided for the central rod 35 to move inwardly of the longitudinal cavity 34 of the lower punch 3 due to a constraint exerted from the upper punch 4 when said upper punch 4 with respect to the lower punch 3.

Indeed, as will be seen below, one of the objectives is to provide a multilayer tablet having a cavity, and more specifically a multilayer tablet, one of the end layers has a through cavity so as to access the immediately adjacent layer through this through cavity.

When bringing the upper punch 4 closer to the lower punch 3, the compacted powder mixture forms a compacted layer having a blind cavity, this blind cavity corresponding to the volume of the central rod 35 projecting from the active surface 32 of the punch lower 3. The fact that the central rod 35 retracts partially during the application of a certain compaction stress implies that the same central rod 35 will be deployed during the relaxation of the compaction stress, so as to come drill the lid closing the blind cavity of the layer to create a through cavity.

More preferably, the elastic connection 36 has a sufficient return constant so that the central rod 35 remains at least partially projecting with respect to the active surface 32 of the lower punch 3 when the upper punch 4 is brought closer to the punch. lower 3.

The fact that the central rod 35 can remain at least partially protruding from the active surface 32 of the lower punch 3 ensures that the cavity formed in the first compacted layer is never completely filled. In particular, when the powder mixture intended to form the adjacent layer is compacted, this mixture can partially fill the cavity of the first layer, in particular if the compaction stress applied is important.

More preferably, the elastic connection has a stiffness constant of between 0.1 daN / mm and 10 daN / mm, preferably between 0.2 daN / mm and

4 daN / mm, more preferably between 0.5 daN / mm and 3 daN / mm, and still more preferably between 1 daN / mm and 2.5 daN / mm.

The stiffness constant chosen may be a function of the compaction force applied. Thus, preferably, a suitable elastic connection is chosen for a compaction force of between 10 kN and 500 kN, preferably between 20 kN and 200 kN, and more preferably between 30 kN and 150 kN.

As indicated above, and as will become more clearly apparent from the description of the compaction process hereinafter, the central rod 35 has an axial displacement inside the longitudinal cavity 34 which is dependent on the compaction stress applied to the powder mixture to be compacted, this compaction constraint being dependent on the relative positioning of the lower and upper punches 4.

In certain phases of the compaction cycle, and in particular during the ejection of the compacted tablet formed, it is preferable for the central rod 35 to be in a retracted position in which it does not protrude with respect to the active surface 32 of the punch. lower 3, that is to say that the central rod 35 is entirely inside the longitudinal cavity 34.

This makes it possible to very easily exit the compacted tablet from the turntable 1 of the press, for example by a sweep that moves the tablet radially outwardly of the turntable 1. For this purpose, the lower punch 3 preferably comprises an actuating member 37 fixedly mounted on the central rod 35 and extending radially with respect to said central rod 35.

This actuating member 37 projects laterally with respect to the body 33 of the lower punch 3 through a groove 38 formed in said lower punch 3.

The actuating member 37 may for example be in the form of a ring surrounding the body 33 of the lower punch 3.

This actuating member 37 is provided to abut against the die 2 during a movement of the lower punch 3 in the direction of said die 2. Once the actuating member 37 is in abutment, the displacement of the punch lower 3 in the direction of the die 2 tends to enter the central rod 35 in the longitudinal cavity 34, to position it in the retracted position in which the central rod 35 no longer protrudes with respect to the active surface 32 of the punch lower 3.

One of the advantages of the device presented above is that it is adaptable to any standard rotary press, that is to say any press having conventional lower and upper punches, with a solid body and an active surface mounted to the end of the body.

Indeed, it is sufficient to replace the lower punch of a standard rotary press by the lower punch presented above, to form a press device for manufacturing tablets with complex shapes, including multilayer and cavity, as described more far. In a very advantageous manner, the lower punch presented may in particular cooperate with any type of upper punch, where it will simply be necessary to adapt the stiffness of the elastic connection on which depends the displacement of the central rod.

Figures 6a to 61 illustrate a method of manufacturing a multilayer compacted tablet with a cavity with a press device as presented above.

In a step E1, we first take a first mixture in the form of powder for forming the first layer 1 10 of the tablet 100 provided with a cavity 1 1 1.

The upper punch 4 is brought to the upper position. The lower punch 3 is brought into the lower position with the central rod 35 fully extended under the action of the elastic connection 36.

As illustrated in FIG. 6a, the first mixture is then placed in the open space formed by the lower punch 3 and the die 2, so as to cover the active surface 32 of said lower punch 3 as well as the central rod 35 projecting from report to said active surface 32. The powder comes for example to fill the entire cavity formed by the matrix 2 and the lower punch 3.

Figure 6b illustrates the dosage of the first mixture, to maintain the exact amount desired for compaction of the first layer. The upper punch 4 is always in the up position, and the lower punch 3 goes up in the die 2 to keep only the desired amount of the first powder mixture.

Preferably, the height of the powder to be compacted corresponds substantially to the height of the portion of the central rod 5 projecting from the active surface 32 of the punch 3. More preferably, a thin layer of powder of between 0.05 mm and 1 mm covers the central stem itself.

The next step E2, as illustrated in FIG. 6c, consists of compacting the first powder mixture. To this end, the upper punch 4 approaches the lower punch 3 so as to exert a compaction stress on the first mixture to form a first compacted layer, said compaction stress also allowing a displacement of the central rod 35 towards the first one. Inside the longitudinal cavity 34. The compacted layer thus formed has a blind cavity as described above, this blind cavity corresponding to the volume of the central rod 35 having remained projecting with respect to the active surface 32 of the lower punch 3.

In the next step E3, as shown in FIG. 6d, the upper punch 4 is moved away from the lower punch 3 so as to eliminate the compaction stress on the first mixture so that the central rod 35 resumes its deployed position relative to to the lower punch 3 under the action of the elastic connection 36. The central rod 35 thus pierces the first layer so as to form a through cavity in place of the blind cavity formed in the previous step.

It is then necessary to form a second compacted layer on this first pierced layer. Thus, in a step E4, it comes to take a second mixture in the form of powder for composing the second layer 120 of the tablet 100.

As illustrated in FIG. 6e, the second mixture is then placed in the open space formed by the lower punch 3 and the die 2, so as to cover the first compacted layer.

Figure 6f illustrates the dosage of the second mixture, in order to maintain the exact amount desired for the compaction of the second layer. The upper punch 4 is always in the high position, and the lower punch 3 back in the die 2 to keep only the desired amount of the second powder mixture.

The next step E5, as illustrated in FIG. 6f, consists in compacting the second powder mixture on the first compacted layer. For this purpose, the upper punch 4 approaches the lower punch 3 so as to exert a stress of compaction on the second mixture and the first layer to form a second compacted layer on the first layer.

Under the effect of the compaction stress, and as a function of the restoring constant of the elastic connection 36, the central rod 35 can be moved inwardly of the longitudinal cavity 34. beyond the contact surface between the first compacted layer and the second powder mixture, then the second compacted powder mixture will partially fill the through cavity 1 1 1 of the first compacted layer 1 10.

In the next step E6, the upper punch 4 is moved away from the lower punch 3 so as to eliminate the compaction stress on the compacted assembly formed by the first and second layers.

If it is desired to form a cavity tablet having only two layers, it is possible, in a step E7, to eject the compacted assembly out of the matrix 2 by a translation of the lower punch 3. Before this ejection, a constraint will have been exerted additional compaction on the compacted two-layer thus formed to reinforce the cohesion of the assembly and thus finalize the compaction of the compacted product.

If it is desired to form a cavity tablet with more than two layers, then the successive steps E4, E5 and E6 are repeated as many times as it is desired to add additional layers to the compacted assembly.

Thus, as illustrated in FIGS. 6h to 6k, a third layer 130 may be formed on the compacted two-layer assembly. To do this, it comes to take a third mixture in powder form for composing the third layer 130 of the tablet 100.

As illustrated in FIG. 6h, the third mixture is then placed in the open space formed by the lower punch 3 and the die 2, so as to cover the second compacted layer.

Figure 6i illustrates the dosage of the third mixture, in order to maintain the exact amount desired for the compaction of the third layer. The upper punch 4 is always in the high position, and the lower punch 3 back in the die 2 to keep only the desired amount of the third powder mixture.

The next step illustrated in FIG. 6j consists of compacting the third powder mixture on the compacted two-layer assembly. For this purpose, the upper punch 4 approaches the lower punch 3 so as to exert a compaction stress on the third mixture and the compacted two-layer assembly to form a third compacted layer on the compacted two-layered assembly.

To finalize the compaction, an additional compaction stress is applied to the compacted three-layer structure thus formed to reinforce the cohesion of the whole. Thus, as illustrated in FIG. 6k, in addition to moving the upper punch 4 downwards, the lower punch 3 can also move upwards, which increases the compaction stress.

The upper punch 4 is then moved away from the lower punch 3 so as to eliminate the compaction stress on the compacted three-layered assembly, and so as to release the die 2.

According to the step E7 described above, and now illustrated in FIG. 61, the compacted three-layer assembly is then ejected out of the die 2 by a translation of the lower punch 3. The lower punch 3 goes up so as to make the active surface 32 of said lower punch 3 with the surface of the turntable. The compacted thus ejected forms the compacted tablet desired.

Preferably, the movement of the lower punch 3 in the direction of the die 2 during the ejection step E7 makes it possible to move the central rod 35 in a retracted position in which the central rod 35 does not protrude with respect to the active surface of the lower punch 3. This indeed facilitates the ejection step of the compacted tablet formed. This is for example achieved through an actuator 37 adapted integral with the central rod 35, as described above in detail.

The specific rotary press and method described above makes it possible to produce multilayer tablets where the different layers have a particular arrangement which makes it possible to confer on the compacted tablet advantageous, mechanical, but also functional properties.

Multi-layer compacted tablets are thus produced, wherein each layer is formed from a mixture in powder form, comprising a first layer having a specific shape with a through cavity along its longitudinal axis and at least a second layer formed directly on the first layer and also having a shape similar to the first layer, with dimensions.

The first layer can also be called the pierced layer of the tablet. As will be seen below, this first layer is indeed the only layer having a through hole formed by the specific arrangement of the central rod in the lower punch.

A specificity of the formed tablet is that the second layer fills less than 70% of the cavity volume of the first layer. As the second layer is not pierced, the cavity of the first layer is filled uniformly and progressively from the contact surface between the first and the second layer. The volume of the cavity of the first layer which is not filled by the material composing the second layer is therefore on the side of the free surface of the first layer. Preferably, the second layer fills less than 50% of the volume of the cavity of the first layer, preferably less than 30% of the volume of the cavity of the first layer, more preferably less than 20% of the volume of the cavity of the first layer. the first layer, or even less than 10% of the volume of the cavity of the first layer.

According to another preferred embodiment, the second layer has a surface flush with the surface of the first layer without the second layer extending into the cavity of the first layer. In this, the second layer does not come at all inside the through cavity of the first layer.

FIGS. 7a and 7b illustrate a particular embodiment of a three-layered compacted tablet, such as for example made with the method described above, comprising a first layer 1 pierced with a through-cavity 1 1 1, associated with a second layer 120, and a third layer 130 on the second layer 120.

According to this embodiment, the second layer 120 is flush with the through cavity 1 January 1 without the powder of the second mixture enters the through cavity 1 January.

The fact that the through-cavity 11 of the first layer 1 is essentially free of the composition forming the second layer 120 confers shelf-specific properties which are particularly advantageous and which will stand out better from the tests described hereinafter. .

In particular, such an arrangement makes it possible to guarantee good disintegration of the different layers. The disintegration of the second layer 120 is particularly favored by the fact that the contact with the solution takes place not only by the peripheral edges but also through the through cavity 1 1 1. In addition, since the second layer 120 is not extends little or no inside this through cavity 1 10, the disintegration of the first layer 1 10 is not disturbed.

In all cases, as follows from the manufacturing method described above, and as is also apparent from the figures, the second layer and any other additional layers have no through cavity. These are indeed non-pierced layers unlike the first layer.

The fact that only the first layer is pierced and the other layer or layers are non-pierced provides a tablet with sufficient strength for handling and storage of the tablet, while presenting a complex design, including the possibility to observe the second layer through the through cavity of the first layer which is pierced.

The general form of the multilayer compacted tablet, and therefore of the various layers composing it, can be diverse depending on the need for use, for example a octagonal, rectangular, oval, circular, or other section. Preferably, the compacted tablet has a circular section and therefore generally cylindrical shape.

In the same way, the cavity 1 1 1 formed through the first layer 1 10 may have a section of various shape, for example circular, square, rectangular, diamond, star or other. The shape of the through cavity 11 1 is defined by the shape of the central rod 35, in particular of its section.

The dimensions of the tablet as well as the cavity of the pierced layer are chosen according to the desired activity of the tablet, and its operation. In particular, for a detergent tablet, the shape and dimensions of the layers and the cavity are chosen according to the desired sequences and disintegration times.

Preferably, the through cavity is defined by a cavity height ratio (hc) tablet height (ht) of between 5% and 80% and preferably between 10% and 50%.

Preferably, the through cavity is defined by a surface area ratio of the cavity (Se) on the tablet surface (St) of between 2% and 70% and preferably between 5% and 40%.

For example, for a multilayer tablet having a substantially cylindrical shape, with a circular section of cavity, the diameter of the cavity is between 5% and 80% of the diameter of the first layer of the tablet, and preferably between 10 % and 60%.

In addition to the advantages presented above relating to the specific arrangement of the layers relative to each other, the multilayer compacted tablet proposed has the particularity of having a relatively uniform compaction rate on the entire tablet, in particular that either at the level of the cavity or at the level of the complete tablet. In addition, the compaction rate at the through cavity is low compared to the cavities obtained by the technologies of the prior art, in particular by stamping or fixed rod. This makes it possible to further improve the disintegration time of the tablets, in particular by eliminating the formation of hard cores.

Preferably, the compaction rate of the compacted powder at the through cavity is close to the compaction rate of the complete multilayer tablet. Preferably, the compaction rate of the powder compacted at the cavity differs from the compaction rate of the complete multilayer tablet by less than 5%, preferably less than 3% and more preferably less than 1%. The comparative tests set out below have been carried out to highlight the advantages conferred on compacted multilayer tablets according to the proposed compaction method, with the specific rotary press developed. More specifically, the tests make it possible to compare the tablets formed with different technologies, in particular with a mobile upper punch with a fixed protruding rod (stamping technique), with a fixed lower punch having a fixed protruding rod, or as according to the proposed method with a fixed lower punch having a protruding spring-mounted rod.

Experimental conditions

The objective is to measure the compaction rate of the compacted powder present in the tablet cavity and the disintegration time of the tablets. The tablets are therefore obtained by the following technologies:

- fixed top punch with rod (stamping process)

- fixed lower punch with fixed stem

- Fixed lower punch with spring-mounted rod (method of the invention) The manipulations are performed on a hydraulic press.

The true density of the powder used is measured on a Quantachrome Ultrapycnometer 1000 helium pycnometer according to the following protocol:

the product to be analyzed is weighed in a cell.

the cell is then placed in the measurement chamber of the pyknometer.

- The measuring chamber is then closed and the measurement is started.

at the end of the measurement, the true density of the analyzed product is obtained.

The principle of this measurement is to inject a gas such as helium at a given pressure into a reference chamber, then to relax this gas in the measuring chamber containing the sample by measuring the new gas pressure in this chamber. pregnant. This method is particularly suitable for measuring the volumes and densities of divided or porous solids because the gas enters the cavities.

The compaction rate (T) is defined by the following formula:

T = (da / dv) * 100

in which :

- da is the apparent density of the compacted solid product,

dv is the true density of the powder before compaction.

The bulk density (da) is determined by the following formula:

da = m / V = m / (S * h)

in which :

m is the mass of the compacted solid product, in grams,

- V is the volume of the compacted solid product, in cm3, S is the surface of the compacted solid product, in cm 2,

h is the height of the compacted solid product, in cm, measured for example by means of a caliper after the ejection of the solid product out of the die of the press used for the compaction.

The shaped shelves have a cylindrical shape with a diameter of 32 mm. The cavity also has a cylindrical shape, with a diameter of 10 mm.

For the stamping process, the following elements are used:

a cylindrical lower fixed punch 32 mm in diameter, with a planar circular active surface;

a matrix with a cylindrical cavity 32 mm in diameter;

a cylindrical movable upper punch 32 mm in diameter, with a planar circular active surface having a projecting fixed rod, the rod having a diameter of 10 mm and exceeding the active surface of the 3.84 mm punch.

For the process using a fixed lower punch with a fixed rod, the following elements are used:

a cylindrical lower fixed pin 32 mm in diameter, with a planar circular active surface having a projecting fixed pin, the rod having a diameter of 10 mm and exceeding the active surface of the 3.84 mm punch;

a matrix with a cylindrical cavity with a diameter of 32 mm;

a cylindrical movable upper punch 32 mm in diameter, with a planar circular active surface.

For the method of the invention using a fixed lower punch with a spring-loaded rod, the following elements are used:

- a cylindrical lower fixed punch 32 mm in diameter, with a planar circular active surface having a rod projecting movably and mounted on a spring

(stiffness constant of 1.05 daN / mm and length of 20 mm), the rod having a diameter of 10 mm and exceeding the active surface of the punch in the extended position of 5.62 mm;

a matrix with a cylindrical cavity with a diameter of 32 mm;

A bilayer tablet is made where the composition of the powder mixtures for the two layers are identical. One of the two layers has a mass of 13.5g and the other of the two layers has a mass of 4.5g, a tablet having a total mass 18g. The tests are successively carried out for a dishwasher formula, a washing machine formula and a disinfectant formula.

A precompaction force of 5kN (6.2MPa pressure) is applied on the first layer and a final compaction of 40kN is applied (ie 49.7MPa pressure) for the dishwasher formula and for the disinfectant formula to compress the two layers of the tablet. A final compaction of 30kN is applied (ie a pressure of 37.3MPa) for the formula linen.

Tests performed on a dishwasher detergent powder

The dishwashing detergent powder used is composed of the ingredients detailed in the following Table 1:

Table 1

The true density of this detergent powder measured as previously described on the helium pycnometer is 2.0171 g / cm3.

The compaction rate measurements of the compacted powder present in the cavity of the tablets and the disintegration time of the tablets obtained by the three technologies described above are listed in Table 2 below.

The disintegration time of the tablets obtained is measured on equipment that goes back and forth with a frequency of 60 strokes / min. The shelves are placed in a basket with multiple holes to let the water through. The baskets are soaked in beakers of 1 .8L of water at 30 ° C. The disintegration time is noted once the tablet is completely disintegrated and there are no shelf residues in the basket. Table 2

Tests carried out on a laundry detergent powder

The detergent powder for the laundry used is composed of the ingredients detailed in the following Table 3:

Table 3

The true density of this detergent powder measured as above is 1.7508 g / cm 3. The compaction rate measurements of the compacted powder present in the cavity of the tablets and the disintegration time of the tablets obtained by the three technologies described previously are listed in Table 4 below.

The disintegration time of the tablets obtained is measured statically in a beaker of 1 L of water at 20 ° C. The disintegration time is noted once the tablet is completely disintegrated.

Table 4

Tests performed on a disinfectant formula

The disinfectant powder used is composed ingredients detailed in the

Table 5 below:

Table 5

The true density of this disinfectant powder measured as previously described is 1.8641 g / cm3.

The compaction rate measurements of the compacted powder present in the tablet cavity and the disintegration time of the tablets obtained by the three technologies described above are listed in Table 6 below.

The disintegration time of the tablets obtained is measured statically in a beaker of 1 L of water at 20 ° C. The disintegration time is noted once the tablet is completely disintegrated. Table 6

All the tests presented above show that the multilayer tablets formed by the proposed method have a very homogeneous compaction rate within the tablet, in particular between the compaction rate of the compacted powder at the cavity and the compaction rate. of the complete multilayer tablet.

On the contrary, it can be seen that the tablets formed with the processes of the prior art have compaction rates that vary substantially according to the area of the tablet.

The tests presented show, moreover, that the tablets proposed have improved disintegration properties since the disintegration time is greatly reduced.

In addition, the above conclusions are valid regardless of the composition forming the tablet, which is very advantageous.

BIBLIOGRAPHIC REFERENCES

- EP0979862

- WO01 / 98448

- WO01 / 49815

EP1 179042

- EP1244767

- WO2006 / 048606

- WO00 / 10800

- WO01 / 85437

- EP1440790

Claims

1. A press apparatus for producing compacted tablets from at least one powdered mixture, comprising:

a turntable (1) in which is provided at least one die (2) for receiving the mixture,

at least one compaction assembly comprising a lower punch (3) and an upper punch (4) each having an active surface for compaction, said lower and upper punches being arranged on either side of the plate (1) with their surface active respective opposite the matrix (2), and being mounted movable in translation coaxially with the matrix (2) and following the rotary movement of the plate,

in which the lower punch comprises a longitudinal cavity (34) open on the die side, inside which is mounted a central rod (35) movable in translation relative to the lower punch along an axis of translation, characterized in that that the central rod (35) is coupled to the lower punch (4) via an elastic connection (36) provided along the axis of translation of the central rod (35) to maintain, in the rest position, the central rod in a maximum deployed position in which the central rod protrudes from the active surface of the lower punch (4), the elastic link (36) having a return constant provided for the central rod to move inwardly of the longitudinal cavity of the lower punch due to a stress exerted from the upper punch on approaching said upper punch with respect to the lower punch.

2. Device according to claim 1, wherein the central rod is secured to the lower punch so that in the absence of stress applied to the central rod, said central rod remains in a fixed position relative to the lower punch when a movement of said lower punch.

3. Device according to any one of claims 1 or 2, wherein the upper punch has a full flat or curved active surface.

4. Device according to any one of claims 1 to 3, wherein the elastic connection has a sufficient return constant so that the central rod remains at least partially projecting relative to the active surface of the lower punch at a reconciliation. of the upper punch with respect to the lower punch.

5. Device according to any one of claims 1 to 4, wherein the elastic connection has a stiffness constant of between 0.1 daN / mm and 10 daN / mm, preferably between 0.2 daN / mm and 4 daN / mm, preferably between 0.5 daN / mm and 3 daN / mm, and more preferably between 1 daN / mm and 2.5 daN / mm.

6. Device according to any one of claims 1 to 5, comprising a resilient connecting member interposed between the central rod and the lower punch to form the elastic connection, the elastic connecting member is preferably selected from a spring, a elastic compression rod, or pneumatic cylinder.

7. Device according to any one of claims 1 to 6, comprising an actuating member fixedly mounted on the central rod and extending radially relative to said central rod, said actuating member projecting laterally relative to the punch lower through a groove in said lower punch, said actuator being provided to abut against the die to position the central rod in a retracted position in which the central rod does not protrude from the active surface of the lower punch.

8. A method of manufacturing a compacted tablet having at least two layers with a press device according to any one of claims 1 to 7, comprising the following successive steps:

E2. Approximation of the upper punch relative to the lower punch so as to exert a compaction stress on the first mixture to form a first compacted layer, said compaction stress further allowing a displacement of the central rod towards the interior of the longitudinal cavity ;

E3. Distancing the upper punch from the lower punch so as to eliminate the compaction stress on the first mixture so that the central rod resumes its extended position relative to the lower punch, the central rod thereby piercing the first layer so as to form a through cavity;

E6. Distance of the upper punch relative to the lower punch so as to eliminate the compaction stress on the compacted assembly formed by the first and second layers; E7. Ejection of the compacted assembly out of the matrix by a translation of the lower punch so as to flush the active surface of said lower punch with the surface of the turntable, the compacted assembly thus ejected forming the compacted tablet.

9. The method of claim 8, wherein during the ejection step E7, the movement of the lower punch towards the die moves the central rod in a retracted position in which the central rod does not protrude by relative to the active surface of the lower punch.

10. Process according to any one of claims 8 or 9, wherein before the ejection step E7, it repeats the successive steps E4, E5 and E6 as many times as it is desired to add additional layers to the compacted set.

1 1. Method according to any one of claims 8 to 10, wherein before the ejection step E7, an additional compaction step is carried out by bringing the upper punch closer to the lower punch so as to exert an additional compaction stress on the whole compacted.

A multilayer compacted tablet, wherein each layer is formed from a powder blend, comprising:

a first layer (1 10) with a through cavity (1 1 1) along a longitudinal axis orthogonal to the first layer (1 10) so as to form a pierced layer; and

at least one second layer (120) formed directly on the first layer (1 10);

characterized in that the first layer is the only pierced layer of the tablet and the second layer fills less than 70% of the cavity volume of the first layer.

13. The tablet of claim 12, wherein the second layer has a surface flush with the surface of the first layer without the second layer extending into the cavity of the first layer.

Tablet according to any one of claims 12 or 13, having a compaction rate of the compacted powder mixture at the cavity differing from the compaction rate of the multilayered tablet completes by less than 5%.

15. Tablet according to any one of claims 12 or 13, having a compaction rate of the compacted powder mixture at the cavity differing from the compaction rate of the multilayer tablet complete less than 3%.

Tablet according to any one of claims 12 or 13, having a compaction rate of the compacted powder mixture at the cavity differing from the compaction ratio of the multilayer tablet complete by less than 1%.

Tablet according to any one of claims 12 to 16, wherein the different layers are formed from powder mixtures for detergent or disinfectant action.