Device and method for compacting a powder

Abstract

The invention relates to a powder compaction device (1) comprising: - a compaction chamber (11) intended to receive the powder and including a filling opening (12); - a compression unit (30) comprising a piston (40) and an actuator (31), the piston being positioned opposite the filling opening and adapted to be moved within the compaction chamber by the actuator; - a shutter (20) movable between a closed position in which the shutter closes the filling opening and a disengaged position in which the shutter is located at a distance from the filling opening. Figure for abbreviation: Fig. 1.

Description

Title of the invention: Device and method for compacting a powder Technical field of the invention

[0001] The present invention relates generally to the field of solid blocks or tablets made of a compacted powder intended for dissolving in aqueous solution before use. More particularly, it relates to a device and a method for compacting a powder. The invention finds a particularly advantageous application in the mass production of solid cosmetics, detergents, or food supplements. It also relates to a powdered composition suitable for manufacturing a compacted powder using the device and the method. In a preferred, but not limiting, application, the invention relates to solid cosmetics. State of the art

[0002] Solid cosmetics that require rehydration address both economic and environmental constraints. Their solid, dry form eliminates the need to transport and package large quantities of water, which can represent up to 90% of the weight of a shower gel, liquid shampoo, or toothpaste. Furthermore, when using solid cosmetics designed to reconstitute liquid cosmetics before use, the user is encouraged to reuse their existing containers to rehydrate new solid cosmetics. Once rehydrated, these containers can be used to reconstitute liquid soaps, shower gels, and liquid shampoos. Solid cosmetics used in this way generally consist of a compacted powder, for example, in the form of tablets or sticks, which facilitates their transport and use.

[0003] In the field of solid cosmetics, powder compaction devices are known for the production of blush or eyeshadow tablets. These devices comprise a housing in which a metal capsule is placed, and the blush powder is agglomerated or compacted within the capsule by means of a piston sliding inside the housing. After the compaction operation, the assembly consisting of the capsule and the blush tablet is ejected from the device, the capsule ensuring the cohesion of the assembly and protecting the tablet from impacts.

[0004] Such a device is not suitable for the production of solid cosmetics as envisaged by the invention which do not include a metal capsule receiving the powder.

[0005] Furthermore, bath salt compaction devices comprising a compaction chamber and a piston are known. The bottom of the chamber and the piston, for example, have complementary hemispherical shapes to obtain spherical bath salts. However, in the absence of a capsule, once the powder is compacted, it is difficult to remove the resulting solid cosmetic from the chamber without risk of damaging it.

[0006] In general, existing devices are not well suited to manufacturing resistant solid cosmetics at a high rate.

[0007] It therefore arose the need for a powder compaction device which has a high production capacity and preferably at low cost while guaranteeing the integrity and visual quality of the solid cosmetic blocks obtained.

[0008] The need also arose for a compactable powder that is sufficiently fluid to efficiently fill the container but which, once compacted, forms a block such as a pellet or stick that is neither fragile nor crumbly, so as to allow its extraction from the container and subsequent transport without risk of damage. Presentation of the invention

[0009] In this context, the present invention proposes a powder compaction device comprising: - a compaction chamber which is intended to receive the powder and which includes a filling opening; - a compression unit comprising a piston and an actuator, the piston being positioned opposite the filling opening and being adapted to be moved in translation within the compaction chamber by the actuator in a main direction; - a movable shutter along a plane substantially orthogonal to the principal direction between a closed position in which the shutter closes the filling opening and a clearing position in which the shutter is located at a distance from the filling opening.

[0010] Thus, thanks to the invention, the compacted powder is not enclosed in the bottom of a container since the compaction surface, namely the shutter, can be moved to the release position, which allows the solid cosmetic to be extracted.

[0011] Advantageously, when the obturator is in the disengaged position, the piston can even continue its run towards the filling opening to remove or eject the solid cosmetic from the compaction chamber.

[0012] Furthermore, the piston remains positioned in the compaction chamber between two compaction cycles, that is, between the manufacture of two solid cosmetics. It is therefore not necessary to remove the piston from the compaction chamber to insert the powder, as is the case in prior art devices.

[0013] Furthermore, the fact that the movement of the shutter is generally perpendicular to the compaction direction allows for the efficient detachment, by shearing, of the solid cosmetic material that has been compacted against the shutter. The recovery of the solid cosmetic material is therefore simplified compared to prior art devices.

[0014] Finally, the device according to the invention makes it possible to precisely dose the quantity of powder to be compacted by choosing the starting position of the piston in the compaction chamber.

[0015] According to one feature of the invention, the principal direction is substantially vertical, with the filling opening located above the piston. This arrangement facilitates, on the one hand, the filling of the compaction chamber by gravity and, on the other hand, prevents the solid cosmetics from falling out when they exit the chambers.

[0016] According to one feature of the invention, the shutter is movable in translation along a direction substantially orthogonal to the principal direction. This movement simplifies the implementation of the shutter while maintaining effective separation of the solid cosmetic product and the shutter. Furthermore, such shutter movement kinematics optimizes the absorption of compaction forces by the shutter.

[0017] According to one feature of the invention, the compression unit comprises: a means for measuring a force exerted by the actuator on the piston; a control unit programmed to determine, on the basis of the force, a speed of movement of the piston.

[0018] According to one feature of the invention, the compression unit comprises: a means for measuring a piston stroke; a control unit programmed to determine, on the basis of the stroke, at least one of a piston displacement speed and a force exerted by the actuator on the piston.

[0019] Adjusting the piston travel speed makes it possible in particular to quickly empty the air contained in the powder in order to increase the production rate while compacting the powder homogeneously.

[0020] According to one feature of the invention, the compaction device comprises a support structure on which the shutter and actuator are fixed, the compaction chamber and piston being held removably relative to the support structure. The shape of the solid cosmetic or block formed can therefore be modified simply by interchanging the compaction chamber with another compaction chamber of the desired shape.

[0021] According to one feature of the invention, the compaction chamber is a cylinder of revolution having a diameter between 10 and 30 mm. Such a shape This allows for the even distribution of radial stresses (perpendicular to the compaction direction) across the entire surface of the cylinder. Such a compaction chamber is therefore very strong.

[0022] According to one feature of the invention, the compaction device comprises: - a plurality of compaction chambers, each intended to receive a portion of the powder and each comprising a filling opening; - a movable shutter between a closed position in which the shutter closes all the filling openings and a disengaged position in which the shutter is located away from all the filling openings; - a compression unit comprising a plurality of pistons and at least one actuator, each piston being positioned opposite one of the filling openings and being adapted to be moved by the actuator into the corresponding compaction chamber.

[0023] The compaction device is therefore particularly suitable for the mass production of solid cosmetics at a high rate. Advantageously, the compaction device comprises only one shutter for all the compaction chambers.

[0024] According to one feature of the invention, the compression unit is adapted to exert on the powder received by each chamber at least one of the following mechanical stresses: - a load between 50 kg and 400 kg; - a compression ratio between 50% and 95%; - a pressure between 1 bar and 20 bar.

[0025] The compacting device, by compacting the powder very strongly, makes it possible to obtain very resistant solid cosmetics but also to implement a wide variety of powders such as powders comprising a large number of ingredients, for example more than five or six.

[0026] The invention also proposes a method for compacting a powder implemented using the compaction device shown above, the method comprising: - the filling of a compaction chamber with powder, the filling being carried out through a filling opening of the compaction chamber; - the movement of a shutter from a clearance position, in which the shutter is located at a distance from the filling opening, to a closing position, in which the shutter closes the filling opening; - the compaction of the powder by displacement of a piston in the compaction chamber, the compaction comprising an initial phase of air expulsion during which a first set speed is imposed on the piston and a sub phase powder compression sequence during which a second set speed, non-zero and lower than the first set speed, is imposed on the piston.

[0027] Thus, thanks to the invention, the powder is compacted in such a way as to reduce the compaction cycle time while ensuring homogeneous compaction. Indeed, the breakdown of the compaction into an initial phase and a subsequent phase makes it possible, in particular, to quickly remove a large quantity of the air contained in the powder and then to obtain homogeneous compaction of the powder by slowing down the speed of the piston.

[0028] Thus, the compaction process according to the invention makes it possible to produce solid cosmetics in the form of compacted powder at a high rate and low cost. Indeed, it makes it possible in particular to reduce or simplify manual operations by automating a large number of manufacturing steps.

[0029] According to one feature of the invention, when a force exerted by an actuator on the piston or a piston stroke is less than a threshold value, the first set speed is imposed on the piston, and when the force exerted by the actuator on the piston or a piston stroke is greater than the threshold value, the second set speed is imposed on the piston. Thus, when the resistance exerted by the powder is low (air expulsion phase), the piston is moved rapidly to increase the production rate. It is then slowed down to homogenize the powder.

[0030] According to one feature of the invention, the method comprises, after compaction, moving the piston in the opposite direction of the filling opening. This releases the pressure between the solid cosmetic and the shutter against which it has been compacted. Separating the solid cosmetic from the shutter is then facilitated.

[0031] According to one feature of the invention, the method includes, after compaction, moving the shutter from the closed position to the release position in order to be able to remove the solid cosmetic from its compaction chamber.

[0032] According to one feature of the invention, the method comprises, after moving the obturator from the closed position to the release position, moving the piston towards the filling opening.

[0033] According to one feature of the invention, the method comprises, after moving the shutter from the closed position to the release position, extracting the compacted powder from the compaction chamber.

[0034] By removing the solid cosmetic from its compaction chamber, the piston limits or facilitates a delicate manual extraction operation. Furthermore, once the solid cosmetics have been removed by the pistons, the obturator, by moving laterally, can recover the solid cosmetics, for example by sweeping them towards a receptacle. With the filling opening located above the piston, the solid cosmetic does not fall out when the piston pushes it out of the chamber.

[0035] The invention also proposes a powder composition for the manufacture of solid cosmetics to be reconstituted in aqueous medium comprising a compaction promoter which includes a compacting agent in solid form or a compacting agent in liquid form, the compaction promoter being between 5% and 30% by weight, relative to the total weight of the composition.

[0036] Advantageously, the use of a compaction promoter improves the cohesion of the compacted powder and therefore the solidity of the resulting solid cosmetics. However, they make the powdered composition more difficult to handle before compaction (risk of lumps and overheating).

[0037] Thanks to the invention, the proportion of compaction promoter is both low enough so that the powder composition is fine and fluid before compaction, which makes it easy to fill the compaction chamber, and high enough so that the solid cosmetic blocks, i.e. the compacted powder, are shock-resistant.

[0038] According to one feature of the invention, the compacting agent in solid form is between 2% and 30% by weight, relative to the total weight of the composition and is for example selected from a group comprising: zinc citrate, maltrodextrin, trisodium citrate dihydrate.

[0039] According to one feature of the invention, the compacting agent in liquid form is between 2% and 10% by weight, relative to the total weight of the composition and is preferably selected from a group comprising: maltitol, an aroma, a fragrance.

[0040] According to one feature of the invention, the compacting agent in liquid form is not in the aqueous phase. This notably improves the preservation of the solid cosmetic. Preferably, the compacting agent in liquid form comprises less than 1% by weight of water.

[0041] According to one feature of the invention, at least 95% of the particles constituting the composition have a particle size of less than 1 mm, which improves the strength of the solid cosmetic. Advantageously, with a particle size of less than 1 mm, the interfaces between two particles within the solid cosmetic are sufficiently small that the detachment of one of these interfaces does not cause the entire solid cosmetic to break. Preferably, 95% of the particles constituting the composition have a particle size between 0.5 mm and 1 mm.

[0042] According to one feature of the invention, the composition comprises an effervescent agent comprising between 12% and 60% by weight, relative to the total weight of the composition, preferably selected from a group comprising: bicarbonate of sodium, anhydrous citric acid. This quantity of effervescent agent allows for rapid dissolution of the solid cosmetic in an aqueous medium for use.

[0043] According to one feature of the invention, the composition comprises a moisturizing agent of between 5% and 60% by weight, relative to the total weight of the composition, for example selected from a group comprising: erythritol, polysaccharide, anionic polysaccharide, an oily plant extract, a dry aloe vera extract.

[0044] According to one feature of the invention, the composition comprises a gelling agent of between 10% and 20% by weight, relative to the total weight of the composition, preferably selected from a group comprising: sodium alginate, xanthan gum, sodium polyacrylate.

[0045] These quantities of moisturizing agent and gelling agent give the solution comprising the dissolved solid cosmetic a suitable texture.

[0046] According to one feature of the invention, the composition comprises a pH regulator of between 3% and 40% by weight, relative to the total weight of the composition, preferably selected from a group comprising: sodium gluconate, anhydrous citric acid, monosodium citrate. This quantity of pH regulator gives the solution comprising the dissolved solid cosmetic a suitable pH.

[0047] According to one feature of the invention, the composition comprises a preservative of between 5% and 20% by weight, relative to the total weight of the composition, preferably selected from a group comprising: sodium benzoate, potassium sorbate, isopropyl methylphenol, sodium gluconate. This quantity of preservative makes it possible to obtain a cosmetic that is easily storable.

[0048] The invention finally proposes a solid cosmetic to be dissolved in an aqueous medium obtained by compacting a composition such as described above by implementing the process described previously.

[0049] Of course, the various features, variants, and embodiments of the invention can be combined with one another in various ways, provided they are not incompatible or mutually exclusive. Detailed description of the invention

[0050] The following description with regard to the attached drawings, given by way of non-limiting examples, will make it clear what the invention consists of and how it can be carried out.

[0051] On the attached drawings:

[0052] [Fig-1] is a schematic cross-sectional view of a compaction device according to the invention in which the shutter is in the disengagement position;

[0053] [Fig.2] is a schematic cross-sectional view of the compaction device of [Fig.1] in which the shutter is in the closed position;

[0054] [Fig.3] is a schematic top view of the compaction device of the [Fig.1] in which the shutter is in the disengaged position;

[0055] [Fig.4] is a block diagram of a sequence of steps enabling the implementation of a compaction process according to the invention;

[0056] [Fig.5] is a schematic graphical representation of the setpoint speeds of the pistons of the compaction device of [Fig.1] during compaction;

[0057] [Fig.6] is a schematic graphical representation of the position of the pistons of the compaction device of the [Fig.1] during a compaction cycle.

[0058] A powder compaction device according to the invention, designated as a whole by reference numeral 1, comprises: - a plurality of compaction chambers 11, each intended to receive a portion of the powder 2, each compaction chamber 11 comprising a filling opening 12; - a compression unit 30 comprising a plurality of pistons 40 and at least one actuator 31, each piston 40 being associated with a compaction chamber 11; - a movable shutter 20 between a closed position in which the shutter 20 closes each filling opening 12 and a disengagement position in which the shutter is located at a distance from each filling opening 12.

[0059] Powder 2 is a powdered composition comprising particles and is intended here for the manufacture of solid cosmetics. The powdered composition is in a dispersed state before being compacted by the compacting device 1; it is then referred to hereafter as "powder". After being compacted by the compacting device 1, the powdered composition is referred to as "solid cosmetic". Of course, this term is not limiting and should be considered equivalent to a compacted block in the context of the manufacture of detergents or food supplements.

[0060] Each compaction chamber 11, when filled with said portion of the powder 2, makes it possible to manufacture a solid cosmetic. In the following description, this portion of the powder 2 filling the compaction chamber 11 is more simply referred to as "the powder" filling the compaction chamber 11.

[0061] As can be seen in Figures 1 and 2, the compaction device 1 also includes a support structure 3 which securely holds the compaction chambers 11, the obturator 20 and the compression unit 30 together so as to compensate for the forces of the compression unit 30 to ensure the compaction of the powder 2 against the obturator 20. As shown in [Fig.3], the compaction device 1 here includes two actuators 31.

[0062] Each compaction chamber 11 has a generally cylindrical shape in that it comprises an internal surface which is cylindrical and whose generatrices extend parallel to a principal direction DI, which here is the vertical direction (corresponding to the up-down direction in Figures 1 and 2). The compaction chambers 11 will hereafter be referred to interchangeably as "compaction cylinders" 11 or "compaction chambers" 11. The compaction cylinders 11 are shown as dashed lines in Figures 1 and 2; each dashed line represents, more specifically, a generatrix of a compaction cylinder IL.

[0063] As shown in [Fig. 1], each compaction cylinder 11 comprises two opposing openings located respectively at its two bases. Each compaction cylinder 11 thus comprises a filling opening 12, through which the powder 2 is placed in the compaction cylinder 11, and a working opening 13 through which the associated piston 40 passes. The filling openings 12 are located above, and here vertically, the working openings 13.

[0064] Preferably, each compaction cylinder 11 more specifically has an internal surface extending along a cylinder of revolution with a diameter between 10 mm and 30 mm. The solid cosmetics produced are then in the shape of a cylinder of revolution. The length of the compaction cylinders 11, that is to say their dimension along the principal direction D1, is for example between 5 mm and 200 mm.

[0065] Alternatively, the compaction cylinders may have a cross-section of another shape such as a hexagonal or rectangular section.

[0066] As shown in [Fig. 1], the compaction device 1 comprises a cylinder block 10 within which the compaction cylinders 11 are held or arranged. The cylinder block 10 is here a support piece with a generally parallelepiped shape. Preferably, all the compaction cylinders 11 installed within the cylinder block 10 are identical.

[0067] As shown in [Fig. 1], the cylinder block 10 has a substantially flat filling face 14 that extends substantially horizontally. Each filling opening 12 opens at the level of the filling face 14.

[0068] The compaction cylinders 11 are specifically mounted removably within the cylinder block 10. Each compaction cylinder 11 is thus formed by an interchangeable sleeve, which allows the desired shape of the solid cosmetic to be adapted. It is therefore possible to mount compaction cylinders with rectangular or square cross-sections to form parallelepiped-shaped solid cosmetics. Furthermore, means are provided for fixing the cylinders to the cylinder block 10, for example, threaded holes and passages in the compaction cylinders 11 and in the cylinder block 10, so as to secure them together by means of screws.

[0069] The compaction cylinders 11, i.e. here the sleeves, are made of metallic material such as, for example, aluminium, stainless steel or polytetrafluoroethylene.

[0070] Alternatively, the compaction cylinders could be formed by bores passing through a solid cylinder block.

[0071] The pistons 40 are positioned opposite the filling openings 12. The pistons 40 are mobile through the working openings 13.

[0072] As shown in [Fig. 1], the compression unit 30 comprises a support plate 32 on which the pistons 40 are mounted. The pistons 40 are mounted here on a front face 33 of the support plate 32. The actuators 31 exert their force at a rear face 34 of the support plate 32 opposite the front face 33. The faces 33, 34 of the support plate 32 extend substantially horizontally.

[0073] Each piston 40 more specifically comprises a head 41, the shape of which is adapted to or complementary to that of the corresponding compaction cylinder 11, and a rod 42. Each head 41 thus has a cylindrical shape with a diameter equal to the diameter of the associated compaction cylinder 11, with a clearance to allow it to be fitted into the latter. The rods 42 have a width, corresponding to a dimension along a direction orthogonal to the principal direction D1, that is less than the diameter of the heads 41

[0074] Like the compaction cylinders 11, the pistons 40 are also interchangeable. For this purpose, the pistons 40 are, for example, removably fixed to the support plate 32. Preferably, only the heads 41 of the pistons 40 are interchangeable, the rods remaining fixed to the support plate 32. The heads 41 can, for example, be screwed onto the rods 42.

[0075] The heads 41 of the pistons 40 are made of polytetrafluoroethylene (PTFE), which limits friction in the compaction cylinders 11. The rods 41 are for example made of aluminium, steel or stainless steel.

[0076] As schematically shown in [Fig. 2], each piston 40 is adapted to be moved by the actuators 31 in the corresponding compaction cylinder 11, i.e., in its associated compaction cylinder 11. [Fig. 2] illustrates a state of the compaction device 1 in which the heads 41 of the pistons 40 are located approximately halfway between the working openings 13 and the filling openings 12.

[0077] Each piston 40 is more specifically adapted to be moved along a generatrix of its associated compaction cylinder 11. The pistons 40 are thus all adapted to be moved along the principal direction DL

[0078] The pistons 40, being moved by the actuators 31, allow the compaction of the powder 2 filling the compaction cylinders 11 against the obturator 20, the latter then being in the closed position.

[0079] The actuators 31 are, for example, electric screw jacks or hydraulic jacks. Thus, the compression unit 30 is adapted to exert, by cylinder of compaction 11, on the powder 2 filling the latter, at least one of the following: - a load between 50 kg and 400 kg; - a compression ratio between 50% and 95%; - a pressure between 1 bar and 20 bar.

[0080] The compression unit 30 also includes a control unit 35 comprising at least one processor, at least one memory, at least one actuator control interface, and a communication interface with sensors or measuring means. The control unit is programmed to control the actuators 31. The control unit 35 is specifically adapted to control the actuators 31 in such a way as to impose a predetermined displacement speed on the pistons 40.

[0081] The compression unit 30 may also include a means for measuring a force exerted by the actuators 31 on the support plate 32, and therefore indirectly on each piston 40. This means for measuring a force is, for example, an electronic circuit for measuring the intensity and / or voltage of the electric current supplied to the actuators 31 to make them operate.

[0082] The control unit 35 is then programmed to determine, on the basis of this force exerted by the actuators 31 on the support plate 32, the speed of movement of the pistons 40.

[0083] The compression unit 30 may also include a means for measuring the stroke of the pistons 40. This stroke measurement means is, for example, an integrator that integrates the speed of the pistons 40 over time based on the electrical current supplied to the actuators 31. This stroke measurement means may also be a displacement sensor that measures the displacement of the actuators 31 or of the support plate 32.

[0084] The control unit 35 is then programmed to determine, based on this stroke, the speed of the pistons 40. The control unit 35 is, for example, programmed by means of instructions entered manually by an operator (for example, via setpoint speeds as described below). In other words, the control unit 35 is adapted to control the speed of the pistons 40 according to a compression ratio, itself determined on the basis of a difference between an initial position of the pistons 40, before compaction, and an instantaneous position of the pistons 40 during compaction.

[0085] As shown in Figures 1 and 2, the shutter 20 comprises a substantially flat compaction face 21. The compaction face 21 is designed to extend into contact with the filling face 12 of the cylinder block 10 when the shutter 20 is in the closed position. In the closed position, the compaction face 21 extends more specifically against the filling face 14 so as to seal the filling openings 12. Here, "seal" means that The obturator 20 closes the compaction cylinders 11 at the filling openings 12, preventing the powder 2 from escaping, but still allowing the air present in the compaction cylinders 11 to escape. In other words, "closing" here means making it airtight to the powder 2 but not to air.

[0086] The obturator 20, for example, has a plate shape whose thickness, here its dimension along the principal direction Dl, is sufficiently large to resist the compaction of the powder 2, i.e., here, to avoid deformation during compaction. The thickness of the obturator 20 is, for example, between 3 mm and 200 mm. The obturator 20 can be made of metallic material, for example, stainless steel, polytetrafluoroethylene, or a combination of these materials.

[0087] The shutter 20 is movable between the open position, as shown in [Fig. 1] and [Fig. 3], and the closed position as shown in [Fig. 2]. In the open position, the shutter 20 leaves the filling openings 12 accessible, allowing the compacting cylinders 11 to be filled or, conversely, the solid cosmetics to be removed.

[0088] As schematically shown in Figures 1 and 2, the shutter 20 is more specifically mobile parallel to the filling face 14 of the cylinder block, and more specifically in contact with the latter. Thus, the shutter 20 is horizontally mobile, that is, along a plane substantially orthogonal to the principal direction DL. This notably ensures effective detachment of the solid cosmetics from the compaction face 21 of the shutter 20 against which they have been compacted. The shutter 20 is here translationally mobile, along a direction orthogonal to the principal direction DL, which simplifies its implementation.

[0089] The shutter 20 is here mounted on the support structure 3 by means of guide rails 22. Preferably, as shown in [Fig.3], two rails 22 are located laterally, i.e. along the two opposite sides of the compaction face 21 which extend in the direction of translation of the shutter 20. As illustrated in [Fig.3], this allows the cylinder block 10 to remain easily accessible when the shutter 20 is in the disengaged position.

[0090] To move the shutter 20, the compaction device 1 includes for example a dedicated actuator (not shown) also controlled by the control unit 35.

[0091] The compaction device 1 enables the compaction process shown in [Fig. 4] to be implemented. The compaction process comprises the following main steps: - filling the compaction cylinders 11 with powder 2; - the movement of the shutter 20 from the release position to the closed position; - the compaction of powder 2 by moving pistons 40 in the cylinders of compaction 11.

[0092] The compaction process here is part of a broader process for manufacturing solid cosmetics or solid blocks of compacted powder. This process for manufacturing solid cosmetics comprises two main phases: a first phase for preparing the powder 2 and a second phase for compacting the powder 2.

[0093] The first phase may include grinding solid ingredients and / or mixing ingredients already in powder form. The composition of powder 2 is described in detail later. However, it can be noted at this stage that the compaction device 1 and the compaction process make it possible to efficiently compact powders with a non-negligible liquid content, for example, one exceeding 2% by weight, which are difficult to compact with prior art devices.

[0094] The second phase of compacting powder 2 corresponds to the implementation of the compaction process presented in [Fig.4].

[0095] Thus, the compaction process begins with the step El of filling the compaction cylinders 11 with the powder 2. The filling can be carried out automatically, for example using an injector mounted on a robotic arm and connected to a reservoir filled with the powder 2, or manually by an operator.

[0096] During filling, the pistons 40 are positioned at a starting position PD inside and at the bottom of the compaction cylinders 11, i.e., near the working openings 13. The starting position PD is predetermined according to the quantity of powder 2 required to form the solid cosmetics. For example, it is determined by considering the final mass of a solid cosmetic and the density of the powder 2. The mass of powder 2 deposited in each compaction cylinder 11 is, for example, between 2 g and 40 g.

[0097] Preferably, a volume of powder 2 greater than the total volume of the compaction cylinders 11 is used to ensure that each compaction cylinder 11 is completely filled. The excess powder 2 is then recovered for reuse. Advantageously, the excess powder 2 can be recovered by moving the obturator 20 from the release position to the closed position (see next step).

[0098] The process then continues with step E2, which closes the filling openings 12. For this, the dedicated actuator moves the obturator 20 from the release position to the closed position. At the end of step E2, in each compaction cylinder 11, the powder 2 is interposed between the corresponding piston 40 and the obturator 20.

[0099] Next, the process continues to step E3 of compacting the powder 2 included in each compaction cylinder 11. During step E3, the control unit 35 determines, in particular, the speed of movement of the pistons 40.

[0100] Remarkably, the compaction, i.e., the movement of the pistons 40 from the starting position PD to a final position PF, comprises two successive phases PI, P2, as shown in Figures 5 and 6. The compaction also includes the starting and stopping of the pistons 40, which occur respectively before and after the two phases PI, P2. The final position PF corresponds to the position of the pistons 40 at the end of the compaction of the powder 2, in the sense that, at the final position PF, the solid cosmetics are formed. It thus corresponds to a final compression ratio of the powder 2. Figure 6 illustrates the stroke of the pistons 40 along the main direction DI.

[0101] Compaction begins with an initial phase PI, characterized by the expulsion of air from the powder and the compaction cylinders 11. As shown in [Fig. 6], during the initial phase PI, the pistons 40 advance rapidly. The pistons 40 are then moved by the actuators 31 at a first set speed, called the expulsion speed VI, which is determined by the control unit 35. This speed is selected to rapidly expel the majority of the air contained in the powder 2. After a very short transient state due to their start-up, the pistons 40 advance overall at the expulsion speed VI during the initial phase. During the initial phase, the expulsion speed can be constant, as shown in [Fig. 5], or vary, for example linearly, within a given range.

[0102] The control unit 35 is, for example, programmed to impose the expulsion velocity VI on the pistons 40 until the stroke of the pistons 40, measured by means of a piston stroke measuring means 40, reaches a first threshold value. Equivalently, the pistons 40 can be moved at the expulsion velocity VI until a compression ratio reaches a second threshold value, for example, between 50% and 90%. The first and second threshold values ​​depend, for example, on the density of the powder 2 or on the amount of compaction promoter within the powder 2.

[0103] As shown in [Fig.5], the initial phase PI continues until the reversal time T corresponding to the moment from which the stroke of the pistons 40 is greater than the first threshold value (or the compression ratio greater than the second threshold value).

[0104] In [Fig. 6], the reversal time T corresponds to the intermediate position PI of the pistons 40. In the example in [Fig. 6], the second threshold value (which relates to the compression ratio) is approximately 65%. The compression ratio is calculated here as the ratio of i) the difference between the instantaneous position and the starting position PD of the pistons 40, to ii) the difference between a flush position PA (when the pistons 40 are at the level of the filling openings 12) and the starting position PD of the pistons 40.

[0105] At the reversal time T, a subsequent phase P2 of powder compression begins, characterized in particular by the plastic deformation of the particles composing the powder 2 in order to ensure their agglomeration by sintering. The pistons 40 are then moved by the actuators 31 according to a second set speed called the compression speed V2, which is determined by the control unit 35. Remarkably, during the subsequent phase P2, the compression speed V2 is strictly less than the expulsion speed VI. When the expulsion speed VI is within a given range, the compression speed V2 is less than the lower bound of that range.

[0106] When the actuator 31 is a screw jack driven by an electric motor, the rotational speed of the drive motor, which determines the expulsion speed VI and the compression speed V2, is, for example, between 500 and 4000 rpm, i.e., speeds between 1 mm / s and 400 mm / s (millimeters per second). Preferably, the expulsion speed VI and the compression speed V2 are between 100 mm / s and 250 mm / s. The compression speed V2 is, for example, half the expulsion speed VL

[0107] This slower advance of the pistons 40 allows for homogeneous compaction of the powder 2. The applicant has indeed demonstrated that a compression speed V2 that is too high induces a compaction gradient in the solid cosmetic, the latter being increasingly compact towards the end located against the shutter 20. This slower advance aims to approach a quasi-static process and to achieve a high compression, for example greater than 80%.

[0108] By way of example, when the actuators 31 comprise screw jacks driven by an electric motor, the reversing time T can also correspond to the point at which the torque exerted by the electric motor exceeds a third threshold value. Indeed, during the air expulsion period, the powder 2 offers little resistance to the movement of the pistons. Once the subsequent phase P2 begins, the powder 2 offers significant resistance; it is therefore preferable that the torque supplied be greater than that of the initial phase PL. The third threshold value can be expressed as an absolute value or as a percentage of the nominal torque of the actuators 31.

[0109] During compaction, the initial phase PI corresponds, for example, to 50% to 80% of the total stroke of the pistons 40, between the starting position and the final position PF. The initial phase PI lasts, for example, between 500 milliseconds and 5000 milliseconds. The subsequent phase P2 corresponds, for example, to 20% to 50% of the total stroke of the pistons 40. Similarly, the subsequent phase P2 lasts, for example, between 500 milliseconds and 5000 milliseconds. As shown in [Fig. 6], the subsequent phase P2 is, for example, two to three times shorter than the initial phase PL.

[0110] The initial phase PI and the subsequent phase P2 appear on the [Fig.6] which represents the position of the pistons 40 along the main direction DI during a complete compaction cycle, in the direction in which the pistons 40 leave from and return to the starting position PD.

[0111] As shown in [Fig. 6], the majority of the total stroke of the pistons 40 (between the starting position PD and the final position PF) occurs during the initial phase PI between the starting position PD and the intermediate position PI. It is clear from [Fig. 6] that the remaining portion of the total stroke of the pistons 40 (the minority portion) is completed, during the subsequent phase P2, at a lower speed than during the initial phase PI. The slope of the curve is indeed shallower during the subsequent phase P2.

[0112] It is provided here that, during the subsequent phase P2, the actuators 31 deliver a torque greater than that delivered during the initial phase PL

[0113] At the end of step E3, the powder 2 is compacted, so the solid cosmetic is formed.

[0114] Advantageously, the method then includes a step E4 in which the pistons 40 perform a short retraction movement. This means that the actuators 31 move the pistons 40 away from the obturator 20, for example, over a distance of between 0.2 mm and 2 mm. This relieves the pressure exerted by the solid cosmetics on the obturator 20. In the example of [Fig. 6], the pistons 40 perform a retraction movement from the final position PF to the intermediate position PI. This retraction can be carried out at a speed greater than the expulsion speed VL

[0115] As shown in [Fig.4], the process then includes a step E5 of translating the shutter 20 from the closed position to the released position.

[0116] In step E6, the solid cosmetics can then be removed from the compaction cylinders 11. Here, as shown in [Fig. 6], step E6 involves the movement of the pistons 40 by the actuators 31 towards the filling openings 12 so as to remove at least some of the solid cosmetics from the cylinder block 10. The solid cosmetics can then be easily grasped, for example, manually by the operator.

[0117] The pistons 40 can also be moved to the filling openings 12 so as to be flush with the filling face 14 of the cylinder block 10. In the example of [Fig.6], the pistons 40 are thus moved from the intermediate position PI to the flush position PA.

[0118] To further automate the process, the solid cosmetics can then be moved, or in other words swept, by the shutter 20 towards a receptacle.

[0119] The compaction process ends here with a step E7 of return of the pistons 40 to the starting position PD. As shown in [Fig.6], this return can be carried out at a high speed, for example two to three times greater than the expulsion speed VI.

[0120] The process described above is controlled by the compression unit 30 and in particular by the control unit 35. The control unit 35 includes in memory instructions, in the form of lines of code, which, when executed by the processor, allow the implementation of steps E2 to E7.

[0121] The powdered composition, i.e., powder 2, produced during the first phase, can, for example, be used to manufacture solid cosmetics to be reconstituted in an aqueous medium, such as toothpaste, shampoo, shower gel, liquid soap, face cream, micellar water, or mouthwash. "To be reconstituted in an aqueous medium" here means that the solid cosmetics are intended to be rehydrated in a volume of water to generate a viscous cosmetic or a solution.

[0122] To increase the strength of solid cosmetics, the powder composition includes a compaction promoter which improves the compaction of the powder particles against each other. The compaction promoter is present here at a concentration of between 5% and 30% by weight, relative to the total weight of the composition.

[0123] The compaction promoter may comprise one or more compacting agents in solid form such as zinc citrate, maltrodextrin, trisodium citrate, or citrate dihydrate. The compacting agents in solid form represent between 2% and 30% of the total weight of the composition.

[0124] The compaction promoter may comprise one or more compacting agents in liquid form, such as maltinol, flavorings, or fragrances, for example, essential oils. "In liquid form" means that these compacting agents are added to the composition while in solution. The compacting agents in liquid form represent between 2% and 10% of the total weight of the composition. It should be noted that compaction-promoting agents may also have another function in powdered compositions. The same applies to effervescent agents, moisturizing agents, gelling agents, pH regulators, or preservatives that may be included in the composition.

[0125] Here, the compacting agents in liquid form are non-aqueous in the sense that they are dissolved in an organic solvent such as an oil; therefore, they are not in the aqueous phase. Such non-aqueous compacting agents improve the preservation of solid cosmetics.

[0126] A large majority of the particles included in the composition, for example at least 95% of them, have a particle size of less than 1 mm.

[0127] By way of example, a powdered composition according to the invention for obtaining a solid cosmetic toothpaste comprises, for example, as a percentage of its total weight: - 11.5% moisturizing agent; - 7% compaction promoter; - 12.5% ​​effervescent agent; - 5% preservative; - 10% surfactant; - 8% abrasive agent; - 10.5% pH regulator; - 18% gelling agent; - flavorings, active agents or texturizing agents in varying proportions.

[0128] By way of further example, a powdered composition according to the invention for obtaining a solid cosmetic for shower gel comprises, for example, as a percentage of its total weight: - 10.2% compaction promoter; - 12.5% ​​effervescent agent; - 12% preservative; - 50% surfactant; - 7.5% pH regulator; - 12% gelling agent; - flavorings, perfumes or colorings in varying proportions.

[0129] The present invention is by no means limited to the embodiments described and represented, but a person skilled in the art will be able to make any variation in accordance with the invention, for example with regard to the shape of the compaction cylinders or their number, or the type or number of actuators.

Claims

Demands

1. A device for compacting (1) a powder (2) for the manufacture of solid cosmetics comprising: - a compacting chamber (11) which is intended to receive the powder (2) and which includes a filling opening (12); - a compression unit (30) comprising a piston (40) and an actuator (31), the piston (40) being positioned opposite the filling opening (12) and being adapted to be moved in translation within the compacting chamber (11) by the actuator (31) along a principal direction (Dl); - a shutter (20) movable along a plane substantially orthogonal to the principal direction (Dl) between a closed position in which the shutter (20) closes the filling opening (12) and a disengagement position in which the shutter (20) is located at a distance from the filling opening (12).

2. Compaction device (1) according to claim 1, wherein the principal direction (Dl) is substantially vertical, the filling opening (12) being located above the piston (40).

3. Compaction device (1) according to any one of claims 1 to 2, wherein the compression unit (30) comprises: - a means for measuring a force exerted by the actuator (31) on the piston (40); - a control unit (35) programmed to determine, on the basis of the force, a speed of movement of the piston (40).

4. Compaction device (1) according to any one of claims 1 to 3, wherein the compression unit (30) comprises: - a means for measuring a stroke of the piston (40); - a control unit (35) programmed to determine, on the basis of the stroke, at least one of a velocity of displacement of the piston (40) and a force exerted by the actuator (31) on the piston (40).

5. Compaction device (1) according to any one of claims 1 to 4, comprising a support structure (3) on which the obturator (20) and the actuator (31) are fixed, the compaction chamber (11) and the piston (40) being held removably relative to the support structure (3).

6. Compaction device (1) according to any one of claims 1 to 5 comprising: - a plurality of compaction chambers (11), each intended to receive a portion of the powder (2) and each comprising a filling opening (12); - a shutter (20) movable between a closed position in which the shutter (20) closes all the filling openings (12) and a disengagement position in which the shutter (20) is located away from all the filling openings (12); - a compression unit (30) comprising a plurality of pistons (40) and at least one actuator (31), each piston (40) being positioned opposite one of the filling openings (12) and being adapted to be moved by the actuator (31) in the corresponding compaction chamber (11).

7. Compaction device (1) according to any one of claims 1 to 6, wherein compression unit (30) is adapted to exert on the powder (2) received by each compaction chamber (11) at least one of the following mechanical constraints: - a load of between 50 kg and 400 kg; - a compression ratio of between 50% and 95%; - a pressure of between 1 bar and 20 bar.

8. A method for compacting a powder (2) for the manufacture of solid cosmetics comprising: - filling a compaction chamber (11) with the powder (2), the filling being carried out through a filling opening (12) of the compaction chamber (11); - moving a shutter (20) from a clearance position, in which the shutter (20) is located at a distance from the filling opening (12), to a closing position, in which the shutter (20) closes the filling opening (12);- the compaction of the powder (2) by movement of a piston (40) in the compaction chamber (11), the compaction comprising an initial phase (PI) of air expulsion during which a first set speed (VI) is imposed on the piston (40) and a subsequent phase (P2) of compression of the powder (2) during which a second set speed (V2), non-zero and lower than the first set speed (VI), is imposed on the piston (40).;

9. A method according to claim 8, wherein when a force exerted by an actuator (31) on the piston (40) or a stroke of the piston (40) is less than a threshold value, the first set speed (VI) is imposed on the piston (40) and when the force exerted by the actuator (31) on the piston (40) or a stroke of the piston (40) is greater than the threshold value, the second set speed (V2) is imposed on the piston (40).

10. A method according to any one of claims 8 to 9, comprising, after compaction, moving the piston (40) in the opposite direction of the filling opening (12).

11. Method according to claim 10, comprising, after a displacement of the obturator (20) from the closed position to the release position, a displacement of the piston (40) in the direction of the filling opening (12).

12. A process according to any one of claims 8 and 11, wherein the powder is a compactable powder composition for the manufacture of solid cosmetics to be dissolved in aqueous medium comprising a compaction promoter which includes a compacting agent in solid form or a compacting agent in liquid form, the compaction promoter being between 5% and 30% by weight, relative to the total weight of the composition.

13. A method according to claim 12, wherein the compacting agent in solid form is between 2% and 30% by weight, relative to the total weight of the composition and is preferably selected from a group comprising: zinc citrate, maltrodextrin, trisodium citrate dihydrate.

14. Process of claim 12 or 13, wherein the compacting agent in liquid form is between 2% and 10% by weight, relative to the total weight of the composition and is preferably selected from a group comprising: maltitol, an aroma, a fragrance.

15. A method according to any one of claims 12 to 14, wherein the compacting agent in liquid form is not in aqueous phase.

16. A method according to any one of claims 12 to 15, wherein at least 95% of the particles constituting the composition have a particle size of less than 1 mm.

17. A method according to any one of claims 12 to 16, wherein it is intended to obtain a solid cosmetic to be dissolved in an aqueous medium.

Images