Container head for a cosmetic-product packaging device, device and associated mounting method

Abstract

Container head for a cosmetic-product packaging device, device and associated mounting method The head comprises a neck (22) having a sleeve (30) defining an outer surface (38) and a helical thread (34) projecting radially from the outer surface (38). It includes a closing member (24) comprising at least one complementary helical thread (72). The neck (22) defines an engagement region (40) of the closure member (24), wherein the complementary helical thread (72) engages on the helical thread (34) leaving a non-zero play with the outer surface (38). The neck (22) defines an intermediate transition region (42), and an alignment and clamping region (44), with a transverse range greater than the engagement region (40). In the configuration mounted on the neck (22), the at least one complementary helical thread (72) is disposed in radial interference with the outer surface (38) in the alignment and clamping region (44).

Description

[0001] DESCRIPTION

[0002] TITLE: Container head for a cosmetic product packaging device, device and associated mounting method

[0003] The present invention relates to a container head for a cosmetic product packaging device, including:

[0004] - a neck comprising a sleeve defining a central-axis axial passage and an outer surface, the sleeve comprising at least one helical thread projecting radially from the outer surface;

[0005] - a closure member, configured to switch from a disassembled configuration away from the neck to a configuration mounted on the neck, the closure member comprising at least one complementary helical thread intended to cooperate with the neck, the neck defining an engagement region for the closure member, in which the at least one complementary helical thread engages on the at least one helical thread leaving a non-zero play with the outer surface of the neck.

[0006] The cosmetic product is for example a hair product, a hygiene product, a facial and / or body care product, a makeup product, or a sun protection product.

[0007] More generally, a cosmetic product is a product as defined in EC Regulation No. 1223 / 2009 of the European Parliament and the Council of November 30, 2009, relating to cosmetic products.

[0008] The development of environmentally friendly cosmetic products, i.e. , the design and development of which take account of environmental concerns, is becoming a major concern to help meet planetary challenges. It has therefore become essential to propose more sustainable packaging devices to meet these environmental challenges.

[0009] In this context, it is important to develop packaging devices by promoting the use of renewable raw materials, with a better carbon footprint, and / or with a good index of naturalness and / or natural origin and more particularly of plant origin.

[0010] This is the case in particular by reducing the amount of plastics material used for making a cosmetic-product packaging device, resulting in a decrease in the thicknesses of the walls of the packaging device, in particular at the neck of the container containing the cosmetic product.

[0011] Alternatively, to make the packaging device, it is possible to replace the plastics material with a cellulosic material, examples of which are described for example in FR3139556. Such a packaging device has a reduced environmental impact. However, reducing the amount of plastics material, or replacing plastics material with cellulosic material, is not fully satisfactory in some cases.

[0012] In particular, screwing the closing member onto the neck of the container results in cooperation between the thread of the neck and the complementary thread of the closing member, in particular at the end of the screwing stroke.

[0013] This cooperation occurs away from the outer surface of the neck, commonly referred to as the thread root. The neck thread(s) is / are thus stressed in flexion by the complementary thread(s) of the closure member.

[0014] In the case of a neck of reduced thickness and / or made of cellulosic material, the bending strength of the neck thread(s) is sometimes insufficient to prevent substantial deformation of the neck thread(s) during tightening.

[0015] In particular, for containers made of cellulose material, the method of manufacturing the neck of the container leads to the cellulose fibers being less densely agglomerated at the neck threads, which are located in a recessed portion of the container-forming support. On the other hand, the fibers are more densely agglomerated in the tubular portion of the neck, which is in direct contact with the surface allowing the cellulosic fibers to be retained on the forming support and which is subjected to a greater compressive force during the forming or drying of the container.

[0016] When tightening the closure member on the neck of the bottle, the neck thread(s) are sometimes insufficiently strong, causing in some cases the appearance of a misalignment of the closure member with respect to the neck. This risk exists from the first closure of the neck by the closure member after filling the container with cosmetic product, and also after a plurality of operations of opening / closing the neck by the closure member by a user.

[0017] This generally leads to the axis of the closure member being misaligned and forming an angle with the axis of the neck. There may then be a leak between the neck and the closing member.

[0018] In this case, the product may leak or be contaminated with external pollutants. In addition, the esthetic appearance of the packaging device is impaired, which may lead to the user not purchasing it or discarding it prematurely.

[0019] Furthermore, in the case of a container associated with a closure element adapted to ensure the attachment of a dispensing pump to the neck of the container, with such misalignment between the axis of the closure member and the axis of the neck of the container, the force exerted by a user on the actuating member of the pump is at an angle with respect to the axis of the neck of the bottle, imposing a compressive force localized on a part of the neck and no longer distributed over the entire structure. This local concentration of stresses may exceed the strength of the material constituting the neck and cause degradation of the use of the pump and container.

[0020] US4798303 describes a neck on which a stopper can be mounted, the neck having a general frustoconical shape. Similarly, EP2010435 describes a bottle neck with a constant outside diameter, provided with a frustoconical thread the diameter of which increases towards the bottom of the bottle, on which a stopper is mounted.

[0021] In these two packaging devices, the holding of the stopper on the neck is ensured by direct cooperation between the neck threads and those of the stopper, in particular by a bending stress between these threads. These packaging devices are therefore not suitable for a substantial reduction in neck thickness and / or for a replacement of the plastics material with a cellulosic material.

[0022] An aim of the invention is to have a container head having a neck and a closure member screwed onto the neck, the head having a reduced environmental impact, for example due to the nature of the material that makes it up, or / and thanks to a reduced mass of material used to form it, while ensuring a suitable positioning and tightening of the closure member on the neck, at the first use and even after several uses.

[0023] To this end, the invention relates to a container head of the aforementioned type, characterized in that the neck defines an intermediate transition region, and an alignment and clamping region, with a transverse range greater than the engagement region, and in that, in the neck-mounted configuration, the at least one complementary helical thread is disposed in radial interference with the outer surface, in particular axially away from the at least one helical thread, in the alignment and clamping region.

[0024] Since the complementary thread on the closure member interferes in the radial direction, perpendicular to the central axis, with the external surface in the alignment and clamping region, in particular away in the axial direction from the or each helical thread present on the neck, a more robust mechanical contact occurs between the or each complementary helical thread present on the closure member and a robust region of the neck, consisting of a thread root.

[0025] Thus, in the neck alignment and clamping region, an interaction occurs by mechanical interference in the radial direction between the or each complementary helical thread of the closure member and the thread root on the outer surface of the neck. This produces a robust and reproducible clamping between the neck of the container and the closing member in mounted configuration.

[0026] Furthermore, the bending stress on the or each neck thread by the or each complementary helical thread of the closure member is reduced, which limits their deformation. This is because, in a mounted configuration of the closing member on the neck of the container, the or each thread of the neck is essentially shear-stressed by the or each complementary helical thread of the closing member. Since the shear strength of the or each neck thread is greater than the flexural strength of the or each neck thread, this or these threads are thus less deformed by the or each complementary helical thread of the closure member when it passes from the disassembled configuration away from the neck to the configuration mounted on the neck. The alignment of the axis of the closing member with the axis of the neck is maintained on the first screwing and even after several uses. In addition, the strong clamping resulting from the interaction reinforces the fluidtightness.

[0027] This ensures good preservation of the product contained in the reservoir, no leakage, and a satisfactory esthetic appearance.

[0028] According to variants:

[0029] - the at least one complementary helical thread is in radial interference with the outer surface in the alignment and clamping region over at least 180° around the central axis, preferably over at least 270° around the central axis, or more advantageously over at least 360° around the central axis;

[0030] - the at least one complementary helical thread extends over at least 720° around the central axis and / or wherein the at least one helical thread extends over at least 720° around the central axis.

[0031] The radial interference over at least 180°, preferably over at least 270° of the or each complementary thread of the closure member with the outer surface of the neck in the alignment and clamping region, reinforces the robustness of the connection between the closure member and the neck in the mounted configuration of the closure member and further limits the risk of angular misalignment by the significant cooperation between the complementary thread and the thread root on which it rests.

[0032] This is particularly the case when the thread present on the neck extends over at least two turns, i.e. over at least 720°, around the central axis.

[0033] According to one variant, the at least one complementary helical thread includes an inner end surface arranged in support in the radial direction on the outer surface, in particular axially away from the at least one helical thread, in the alignment and clamping region.

[0034] The presence on the or each complementary helical thread of an inner end surface ensures bearing on a significant area of the complementary helical thread on the outer surface of the neck, in the alignment and clamping region, further enhancing the clamping cooperation in the radial direction of the or each complementary helical thread with the outer surface.

[0035] According to variants: - the at least one complementary helical thread is engaged under the at least one helical thread in the engagement region;

[0036] - the at least one complementary helical thread has an inner end surface disposed radially away from the outer surface in the engagement region;

[0037] - the engagement of the at least one complementary helical thread with the at least one helical thread in the engagement region takes place over at least 180° around the central axis, preferably over at least 270° around the central axis.

[0038] The presence of a complementary helical thread engaged under the helical thread in the engagement region on the neck ensures simple and non-interfering engagement of the closure member on the neck and progressive guiding of the closure member in rotation to the alignment and clamping region.

[0039] Thus the perception of the engagement of the closure member on the neck by the user is initially identical to that which occurs on a conventional container head. This allows the user to adjust the screwing force of the closing member to prevent it from being excessive.

[0040] Such an effect is particularly achieved when the inner end surface of the complementary helical thread is disposed radially away from the outer surface in the engagement region on the body, and engagement of the or each complementary helical thread with the or each helical thread on the neck is preferably obtained over a total angular range of at least 270°.

[0041] According to variants:

[0042] - the intermediate region includes a frustoconical outer surface;

[0043] - the half-angle at the vertex of a cone in which the frustoconical intermediate region is inscribed is between 15° and 60°, preferably between 20° and 30°, and for example close to 27°.

[0044] The presence of an intermediate region having a frustoconical outer surface ensures a gradual transition when tightening the closure member between engaging the closure member on the neck and its effective tightening by cooperation of the or each complementary thread with the outer surface of the neck between the threads.

[0045] This transition is particularly progressive when the angle at the vertex of the cone of the frustoconical intermediate region is within the aforementioned range.

[0046] According to one variant, the neck and / or the closure member is made from cellulosic material or / and is made by blowing extrusion or by blowing injection of plastics material.

[0047] Thanks to the effective clamping provided by the complementary helical thread in radial contact with the external surface, in particular away from the helical thread, it is possible to produce the neck and / or the closure member based on cellulosic material or by methods of blowing plastics material while greatly reducing the thickness of the walls, in particular at the neck.

[0048] As a result, the head contains less plastics material or is produced from material including little plastic, while being able to be used several times reliably and leak-tight by a user.

[0049] In one variant, the closing member is a cap comprising a mechanism for dispensing product out of the container, or is a container-closing stopper.

[0050] The fastening of the closure member on the neck by screwing with a radial interference between the or each complementary helical thread and the thread root on the neck is applicable in particular to a cap comprising a product dispensing system, since the cap is held strongly on the neck, allowing reliable and efficient maneuvering of the product dispensing system. This fixing can also be applied to a stopper while allowing a sealed closure even after several screwing / unscrewing operations.

[0051] In one variant, the sleeve includes an upper free edge extending transversely, the head comprising an annular seal interposed between the free edge of the sleeve and the closing member.

[0052] The effective cooperation between the neck and the closing member makes it possible to interpose a flat seal on the upper free edge of the sleeve constituting the neck, in order to further increase the sealing at the neck.

[0053] In a variant, the outer surface of the neck defines a thread root between successive turns of the at least one helical thread, the at least one complementary helical thread being disposed in radial interference on the thread root in the alignment and clamping region, in the neck-mounted configuration, the at least one complementary helical thread being disposed radially away from the thread root in the engagement region, in the neck-mounted configuration.

[0054] The radial interference of the complementary helical thread with the thread root is particularly advantageous, since the thread root is a mechanically strong zone that ensures a solid support of the complementary helical thread, particularly in the case where the helical thread is made of cellulosic material or of blown plastics material.

[0055] The invention also relates to a cosmetic-product packaging device comprising a container delimiting an inner volume containing cosmetic product, and a head as defined above, protruding from the container.

[0056] The invention also relates to a method for mounting a container head, comprising the following steps: - providing a head as defined above, the closing member being in its unscrewed configuration;

[0057] - engaging the closure member on the engagement region of the closure member, the at least one complementary helical thread engaging on the at least one helical thread leaving a non-zero play with the outer surface of the neck;

[0058] - engaging the at least one complementary helical thread around the alignment and clamping region, the at least one complementary helical thread being placed in radial interference with the outer surface, in particular axially away from the at least one helical thread.

[0059] The invention will be easier to understand after reading the following description, provided solely as an example, and with reference to the appended drawings, wherein:

[0060] - [Fig. 1] figure 1 is a sectional view along a vertical midplane of a cosmetic-product packaging and dispensing device having a receptacle head according to the invention;

[0061] - [Fig. 2] figure 2 is an enlarged sectional view along the vertical midplane of the neck of the container head of Figure 1 , the neck defining from top to bottom a region of engagement of a closure member, an intermediate region and a region of alignment and clamping of the closure member;

[0062] - [Fig. 3] figure 3 is a view identical to figure 2, the closing member being mounted on the neck;

[0063] - [Fig . 4] figure 4 is a view similar to figure 3 of a variant of a packaging and dispensing head according to the invention.

[0064] Hereinafter, the terms "upstream" and "downstream" are understood generally with respect to the normal direction of travel of a cosmetic product during dispensing thereof.

[0065] A first device 10 for packaging and dispensing a cosmetic product according to the invention is illustrated by Figure 1.

[0066] The first device 10 is intended for packaging and advantageously for dispensing a fluid cosmetic product. The cosmetic product is for example a hair product, a hygiene product, a facial and / or body care product, a makeup product, or a sun protection product. The cosmetic product is In particular a liquid, a gel or a cream.

[0067] The device 10 includes a cosmetic-product container 12 and a closing and dispensing head 14 disposed here at an upper end of the container 12 along an elevation axis, or central axis, A-A' of the container 12.

[0068] The container 12 comprises a bottom 16 and a side wall 18 which delimits an inner volume 20 intended to contain cosmetic product. The inner volume 20 is configured to contain for example between 5 ml and 500 ml, in particular between 15 ml and 100 ml of cosmetic product. The head 14 comprises a neck 22 mounted fixed to a downstream end of the container 12 or made in one piece with the container 12. It comprises a closure member 24 which is herein screwed onto the neck 22 to be movable between a configuration disassembled from the neck 22 (not shown) and a configuration mounted on the neck 22, in engagement with the neck.

[0069] In this example, the head 14 further comprises a seal 26 which is interposed between the closure member 24 and the neck 22 to achieve a seal between these elements.

[0070] Advantageously, at least a portion of the container 12, of the neck 22 and / or of the closure member 24 is made of cellulosic material, in particular at least one contact region between the neck 22 and the closure member 24.

[0071] The object made of cellulosic material, here, at least a part of the container 12, of the neck 22 and / or of the closure member 24, is mainly made of cellulosic fibers arranged in a three-dimensional structure. These cellulosic fibers can come from pulp produced from wood fibers or plants.

[0072] The cellulosic material thus comprises for example paper fiber, cardboard fiber, wood fiber, or plant fiber, or paper pulp, or cardboard pulp, or a mixture of these materials.

[0073] Using these materials has the advantage of coming from renewable resources and thus reducing the use of raw materials from the petrochemical sector. These materials can be recycled in the recycling channels dedicated to paper and cardboard. In some advantageous cases, they may also benefit from the biodegradability of cellulosic fibers. Thus the use of these materials improves the recyclability and / or degradability of the device, these materials also advantageously being able to be derived from recycling channels.

[0074] The cellulosic fibers can for example come from trees (for example from resinous fibers, such as pine, fir or spruce or from hardwood fibers, such as birch, beech, poplar, aspen, acacia or eucalyptus), plants, such as bamboo, flax or hemp, or agricultural byproducts such as bagasse, fibrous sugar cane residue, wheat straw, rice straw, corn stems or a mixture of these materials.

[0075] The object made of cellulosic material is for example provided with a coating of another nature applied to its inner surface and / or to its outer surface. The purpose of this coating is to protect the fibers and improve the surface properties of the object made from these fibers.

[0076] The materials used for the coating are generally layers, varnishes, resins that can be organic (polyethylene - PE, polypropylene - PP, polyethylene terephthalate - PET, acrylics or acrylic derivatives, latex, polyhydroxyalkanoate - PHA, polylactic acid - PLA, waxes, paraffins derived from algae or starch) or inorganic (aluminum oxide, silicon oxide for example) and deposited in thicknesses ranging from a few nanometers to several hundred microns.

[0077] In a variant, the material forming the container 12, the neck 22 and / or the head 24 is at least partially made of plastics material, but with a reduced wall thickness, in particular at the neck 22, for example less than 0.5 mm.

[0078] In predefined regions, the container 12, the neck 22 and / or the head 24 are for example made by injection blowing or by extrusion blowing. This leads to a natural reduction of the wall thickness in these certain regions, which can be about 30% in some cases.

[0079] With reference to Figure 2, the neck 22 includes a sleeve 30 defining an inner passage 32 of axis A-A' opening into the inner volume 20. The neck 22 comprises, in radial projection of the sleeve 30, at least one helical thread 34 intended for screwing the closing member 24 onto the neck 22.

[0080] The passage 32 is defined by an inner surface 36 of the sleeve 30. The sleeve 30 also defines an outer surface 38, from which the helical thread 34 projects.

[0081] According to the invention, the sleeve 30 includes, from the outside to the inside, from top to bottom in figure 2, a downstream engagement region 40 for the closure member 24, substantially cylindrical, a frustoconical intermediate region 42, and an upstream region 44 for aligning and clamping the closure member 24, also substantially cylindrical.

[0082] The outer surface 38 extends in this example at a first maximum radial distance D1 from the central axis A-A' in the engagement region 40, away from the helical thread 34.

[0083] The intermediate region 42 is generally frustoconical in shape, the half-angle at the vertex of the cone in which the outer surface 38 is inscribed in the intermediate region 42 is for example less than 60°, in particular between 15° and 60°, better between 25° and 30°, and for example close to 27°. It is recalled here that the half-angle at the vertex of a cone corresponds to the angle formed between the generator of this cone and the central axis of the cone, in this case formed by the central axis A-A'.

[0084] The height of the intermediate region 42, taken along the axis A-A', is generally less than or equal to the height of the engagement region 40, taken along the axis A-A'.

[0085] The alignment and clamping region 44 is cylindrical in shape. The outer surface 38 extends in this example at a second maximum radial distance D2 from the central axis A-A' in the alignment and clamping region 44, away from the helical thread 34, the distance D2 being greater than the distance D1 .

[0086] In this example, the neck 22 comprises a continuous helical thread 34. In a variant (not shown), the neck 22 has a plurality of separate helical threads 34, extending in a helix around the axis A-A'. The helical thread 34 extends over at least 720° around the axis A-A'. Preferably, it extends over at least 270°, preferably over at least 360° in the engagement region 40, and over at least 270°, preferably over at least 360° in the alignment and clamping region 44.

[0087] In this example, the helical thread 34 has, in cross-section along an axial midplane passing through the axis A-A1, from downstream to upstream, an engagement downstream frustoconical surface 50, moving away from the axis A-A' while moving upstream, an external circumferential end surface 52, and an upstream retaining frustoconical surface 54, approaching the axis A-A' axis while moving upstream.

[0088] The angle at the vertex of a cone in which the downstream frustoconical surface 50 is inscribed is less than the angle at the vertex of a cone in which the upstream frustoconical surface 54 is inscribed.

[0089] For example, the half-angle at the vertex of the cone in which the downstream frustoconical surface 50 is inscribed is between 30° and 60° and the half-angle at the vertex of the cone in which the upstream frustoconical surface 54 is inscribed is between 88° and 60°.

[0090] In a variant, the helical thread 34 has, in cross-section along an axial midplane passing through the axis A-A1, a rounded profile, such as in an arc of circle.

[0091] In the example of Figure 2, the circumferential end surface 52 is further away from the axis A-A' in the intermediate region 42 and in the alignment and clamping region 44 than in the engagement region 40.

[0092] In this example, the inner surface 36 of the sleeve 30 delimits a shape substantially complementary to the helical thread 34 opposite the helical thread 34.

[0093] Thus, in the case of a neck 22 made of fibrous materials, the density of cellulosic fibers in the helical thread 34, facing the hollow 56, is lower than the density of the cellulosic fibers in the thread root 58, defined on the outer surface 38 away from the helical thread 34.

[0094] With reference to Figure 3, the closure member 24 includes a cylindrical skirt 70, intended to be inserted around the sleeve 30 of the neck 22 along the axis A-A1, and at least one complementary helical thread 72, intended to engage with the helical thread 34, the complementary helical thread 72 protruding from the skirt 70 towards the axis A-A'.

[0095] The closure member 24 furthermore includes an end transverse wall 74 which, in this example, is annular.

[0096] Also in this example, the closing member 24 carries a mechanism 76 for dispensing product including a pump 78 fixedly mounted between the seal 26 and the end wall 74, a push button 80 for actuating the pump 78 and dispensing product and optionally a dip tube 82, visible in figure 1. The cylindrical skirt 70 defines an outer surface 90 and a cylindrical inner surface 92 from which the complementary helical thread 72 projects.

[0097] The complementary helical thread 72 has a helical shape complementary to that of the or each helical thread 34. It has, in cross-section along an axial midplane passing through the axis A-A', an inner end surface 94, disposed between an upstream surface 96 and a downstream surface 98, the inner end surface 94 being intended to face the outer surface 38 of the sleeve.

[0098] In this example, the radial play defined between the inner end surface 94 of the complementary helical thread 72 in the engagement region 40 with the outer surface 38 is non-zero and positive, when the closing member 24 is screwed onto the neck 22.

[0099] In the engagement region 40, a gap 97 therefore exists in the radial direction between the outer surface 38 away from the helical thread 34 and the inner end surface 94 of the complementary helical thread 72. Thus, during the initial engagement of the complementary helical thread 72 on the helical thread 34, the clamping force is reduced and corresponds to that to be applied for a conventional closing member.

[0100] In the engagement region 40, the downstream surface 98 engages under the upstream frustoconical surface 54 to provide guidance of the helical rotation of the closure member 24 on the neck 22 when screwing the closure member 24 onto the neck 22.

[0101] The helical thread 34 is stressed in flexion by the contact between the upstream frustoconical surface 54 of the helical thread 34 and the downstream surface 98 of the complementary helical thread 72.

[0102] On the contrary, in the alignment and clamping region 44, the inner end surface 94 of the complementary helical thread 72, has zero or preferably negative radial play with the outer surface 38 of the sleeve 30 in the thread root 58, away from the helical thread 34.

[0103] The complementary helical thread 72 is then in radial interference with the root of the thread 58 defined between the successive turns of the helical thread 34. An interaction in the radial direction therefore occurs between the complementary helical thread 72 and the outer surface 38 in the thread root 58, in particular axially away from the upstream frustoconical surface 54.

[0104] Advantageously, there is also contact between the base of the upstream frustoconical surface 54 of the helical thread 34 with the downstream surface 98 of the or each complementary helical thread 72.

[0105] Thus the most significant interference between the complementary helical thread 72 and the sleeve 30 occurs in the thread root 58. This is particularly beneficial in the case where the neck 22 is made of cellulosic material, the density of cellulosic fibers being maximum in the thread root 58, given its cylindrical geometry without hollows. This results in an alignment and robust tightening of the closure member 24 on the neck 22, on the first screwing and even after several screwings / unscrewings of the closure member 24.

[0106] In this example, the product dispensing mechanism 76 is engaged under the end wall 74, with the pump 78 protruding inside the passage 32.

[0107] The push button 80 protrudes axially from the outside of the end wall 74 and is configured to be moved along the axis A-A' to cause activation of the pump 78, and suction of product through the dip tube 82, the pump 78, and at least one product dispensing duct 99 defined within the push button 80.

[0108] In this example, the seal 26 includes a flange 100, arranged in flat contact on the free edge 102 of the sleeve 30 and a cannula 104 protruding from an inner edge of the flange 100 to be inserted in the passage 32, in contact with the inner surface 36.

[0109] The flange 100 is thus arranged flat while being axially clamped on the one hand by the free edge 102 of the neck 22 and on the other hand by the end wall 74 of the closing member 24, with possibly the interposition of the product dispensing mechanism 76.

[0110] The assembly of the packaging and dispensing device 10 according to the invention will now be described.

[0111] Initially, the container 12 provided with its neck 22 is provided. The container 12 and the neck were previously manufactured for example from cellulosic material as defined above, or from plastics material, advantageously by an extrusion plying or injection blowing method, with in particular a reduced wall thickness at the neck.

[0112] When a seal 26 is present, the seal 26 is first of all mounted on the neck 22, by applying the flange 100 to the free edge 102 of the sleeve 30.

[0113] The cannula 104, when present, is inserted into the passage 32, in contact with the inner surface 36 of the neck.

[0114] Alternatively, the seal 26 and the cannula 104 are advantageously carried by the closing member 24 and placed on the neck 22 of the container 12 when the closing member 24 passes from the disassembled configuration to the assembled configuration.

[0115] Then, when the closing member 24 carries a product dispensing mechanism 76, the dip tube 82 and the pump 78 are inserted through the passage 32. The cylindrical skirt 70 engages around the engagement region 40 of the neck 22.

[0116] During this movement, the complementary helical thread 72 of the cylindrical skirt 70 first comes into contact with the helical thread 34 of the neck 22 in the engagement region 40.

[0117] A non-zero radial play exists between the thread root 58 defined on the outer surface 38 in the engagement region 40 and the inner end surface 94 of the complementary thread 72. Subsequently, the user can easily initiate the screwing of the cylindrical skirt 70 on the engagement region 40, with a force comparable to that of a usual screwing over an advantageously angular path of at least 270°.

[0118] Then, the complementary helical thread 72 passes into the intermediate region 42 and reaches the alignment and clamping region 44.

[0119] The radial play between the inner end surface 94 of the complementary thread 72 and the thread root 58 gradually decreases and becomes zero or preferably negative.

[0120] The inner end surface 94 is then applied against the thread root 58, under the upstream frustoconical surface 54 of the or each helical thread 34.

[0121] Thus the or each complementary helical thread 72 is in radial interference with the thread root 58 defined on the outer surface 38 of the sleeve 30 away from the or each helical thread 34.

[0122] The complementary helical thread 72 therefore interacts directly with the outer surface 38 of the neck 22, which reinforces the strength and robustness of the attachment of the closure member 24.

[0123] The helical thread 34 of the neck 22 is stressed mainly in shear by the complementary thread 72 of the closure member 24 in the alignment and clamping region 44 and thus opposes a resistance greater than that it would oppose if it were stressed mainly in flexion.

[0124] This is because the thread root 58 is more robust mechanically than the helical thread 34, for example because the wall thickness is greater with respect to the helical thread root 58 compared with the wall thickness with respect to the helical thread 34 in the case of a neck 22 made by blowing or because the density of cellulosic fibers at the thread root bottom 58 is greater than the density of cellulosic fibers at the helical thread 34.

[0125] A precise and reproducible alignment of the axis of the closing member 24 with the axis of the neck 22 is thus obtained after screwing. Furthermore, as the contact of the inner end surface 94 takes place on the thread root 58, the attachment is robust, even if the screwing is not a first screwing, and even after at least one unscrewing / screwing cycle.

[0126] The radial interference cooperation between the thread root 58 and the complementary helical thread 72 prevents the appearance of strong bending stresses between the or each helical thread 34 of the neck 22 and the complementary helical thread 72 of the closure member 24, which would be likely to substantially deform the or each helical thread 34 of the neck 22 in the alignment and clamping region 44.

[0127] Thus, the tightening is carried out effectively, ensuring a strong seal between the closing member 24 and the neck 22. Since the shear strength of the helical thread 34 of the neck 22 is greater than its flexural strength, the risk of critical deformation of the helical thread 34 when tightening it, and therefore misalignment between the closure member and the neck of the container and / or a leak in the seal is particularly reduced. In addition, material creep is reduced if the material is susceptible to creep.

[0128] In a variant shown in Figure 4, the outer end surface 52 of the or each helical thread 34 in the alignment and clamping region 44 is disposed at a radial distance from the axis A- A' substantially equal to the radial distance from the axis A-A1of the outer end surface 52 in the intermediate region 42 or / and substantially equal to the radial distance from the axis A-A1of the outer end surface 52 in the engagement region 40.

[0129] The outer end surface 52 in the alignment and clamping region 44 is then a cylindrical surface over the entire periphery of the or each helical thread 34, advantageously over a height greater than the wall thickness.

[0130] In a variant of the heads 14 illustrated in figures 3 and 4, the closing member 24 has no product-dispensing mechanism 76. The end wall 74 is solid and the closing member 24 is a neck closure stopper 22.

Claims

CLAIMS1. Head (14) of a container (12) for a cosmetic-product packaging device (10), comprising:- a neck (22) comprising a sleeve (30) defining an axial passage (32) with a central axis (A-A') and an outer surface (38), the sleeve (30) comprising at least one helical thread (34) projecting radially from the outer surface (38),- a closure member (24), configured to move from a disassembled configuration away from the neck (22) to a configuration mounted on the neck (22), the closure member (24) comprising at least one complementary helical thread (72) intended to cooperate with the neck (22), the neck (22) defining an engagement region (40) of the closure member (24), in which the at least one complementary helical thread (72) engages on the at least one helical thread (34) leaving a non-zero clearance with the outer surface (38) of the neck (22); characterized in that the neck (22) defines an intermediate transition region (42), and an alignment and clamping region (44), of transverse range greater than the engagement region (40), and in that, in the configuration mounted on the neck (22), the at least one complementary helical thread (72) is disposed in radial interference with the outer surface (38), in particular axially away from the at least one helical thread (34), in the alignment and clamping region (44).

2. Head (14) according to claim 1 , wherein the at least one complementary helical thread (72) is in radial interference with the outer surface (38) in the alignment and clamping region (44) over at least 180° around the central axis (A-A1), preferably over at least 270° around the central axis (A-A1), or even more advantageously over at least 360° around the central axis (A-A1).

3. Head (14) according to claim 2, wherein the at least one complementary helical thread (72) extends over at least 720° around the central axis (A-A1) and / or wherein the at least one helical thread (34) extends over at least 720° around the central axis (A- A’).

4. Head (14) according to any one of claims 1 to 3, wherein the at least one complementary helical thread (72) comprises an inner end surface (94) arranged in support in the radial direction on the outer surface (38), in particular axially away from the at least one helical thread (34), in the alignment and clamping region (44).

5. Head (14) according to any one of the preceding claims, wherein the at least one complementary helical thread (72) is engaged under the at least one helical thread (34) in the engagement region (40).

6. Head (14) according to claim 5, wherein the at least one complementary helical thread (72) has an inner end surface (94) disposed radially away from the outer surface (38) in the engagement region (40).

7. Head (14) according to any one of the preceding claims, wherein the engagement of the at least one complementary helical thread (72) with the at least one helical thread (34) in the engagement region (40) takes place over at least 180° around the central axis (A-A1), preferably over at least 270° around the central axis (A-A1).

8. Head (14) according to any one of the preceding claims, wherein the intermediate region (42) includes a frustoconical outer surface (38).

9. Head (14) according to claim 8, wherein the half-angle at the vertex of a cone in which the intermediate frustoconical region (42) is inscribed is between 15° and 60°, preferably between 20° and 30°, and for example close to 27°.

10. Head (14) according to any one of the preceding claims, wherein the neck (22) and / or the closure member (24) is made from cellulosic material or / and is made by extrusion blowing or by injection blowing of plastics material.

11. Head (14) according to any one of the preceding claims, wherein the closure member (24) is a cap comprising a mechanism for dispensing product (76) out of the container (12), or is a stopper for closing the container (12).

12. Head (14) according to any one of the preceding claims, wherein the sleeve (30) includes an upper free edge (102) extending transversely, the head (14) comprising an annular seal (26) interposed between the free edge (102) of the sleeve (30) and the closing member (24).

13. Head (14) according to any one of the preceding claims, wherein the outer surface (38) of the neck (22) defines a thread root (58) between successive turns of the at least one helical thread (34), the at least one complementary helical thread (72) being disposed in radial interference on the thread root (58) in the alignment and clamping region (44), in the configuration mounted on the neck (22), the at least one complementary helical thread (72) being disposed radially away from the thread root (58) in the engagement region (40), in the configuration mounted on the neck (22).

14. Cosmetic-product packaging device (10) comprising a container (12) delimiting an inner volume (20) containing cosmetic product, and a head (14) according to any one of the preceding claims, projecting from the container (12).

15. Method for mounting a head (14) of a container (12), comprising the following steps:- providing a head (14) according to any one of claims 1 to 13, the closing member (24) being in its unscrewed configuration;- engaging the closure member (24) on the engagement region (40) of the closure member (24), the at least one complementary helical thread (72) engaging on the at least one helical thread (34) leaving a non-zero play with the outer surface (38) of the neck (22);- engaging the at least one complementary helical thread (72) around the alignment and clamping region (44), the at least one complementary helical thread (72) being placed in radial interference with the outer surface (38), in particular axially apart from the at least one helical thread (34).

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