Title of Invention: Tube head provided with an air non-return grid
Abstract: 
The present invention relates to a tube head for product of fluid to pasty consistency comprising



a neck having at a first end an opening through which the product is extracted from the tube,
a shoulder connected to a second end of the neck opposite the first end, and the tube head comprising an air non-return means placed in said neck, said means being adapted to avoid a return of air from the first end of the neck to the second end of the neck, characterised in that the tube head is one piece.




Detailed Description: 

GENERAL TECHNICAL FIELD
The invention relates to a tube head for product of fluid to pasty consistency, and in particular to a tube head comprising an air non-return system.
STATE OF THE PRIOR ART
A tube may contain a product of fluid to pasty consistency reactive in contact with air (toothpaste, foundation, sun cream, adhesive, paint, medicine, etc.). Indeed, certain products can undergo oxidation on contact with air and thereby lose their chemical properties.
The bringing of air into contact with the product takes place once the protective lid at the opening of the tube head is removed. During use of the product, the user presses the tube in order to expel the product out of the tube via the opening of the head. This opening is formed at the end of a neck constituting the head with a shoulder broadening out from the neck. Thus, the product is present inside the neck at the moment when the user reduces the pressure exerted on the tube.
When the user has extracted sufficient product from the tube for use and releases the tube, the pressure exerted on the tube is reduced. Generally, the physical properties of the tube have a more or less elastic character, which implies that the tube recovers, at least in part, its initial shape (shape before the application of pressure by the user) and induces a return of the product contained in the head.
If this elastic recovery of the tube is small, part of the product inside the neck is sucked towards the shoulder. The part of the product remaining inside the neck ensures a plugging of the neck vis-à-vis external air. Since the neck has a relatively low internal volume, of the order of several mm3, compared to the internal volume of the shoulder or the tube, this implies that a very small quantity of external air is present in the tube at the neck and that a very small quantity of product is in contact with the air.
However, if this elastic recovery is important, all of the product present in the neck can return to the shoulder until the neck is completely empty. Consequently, the whole neck as well as a portion of the shoulder, or even all of the shoulder, receives external air through suction, which considerably increases the volume of air housed inside the tube and significantly increases the aforementioned risks of oxidation of the product contained in the tube.
If the cap of the tube is then closed, the oxygen from the air sucked into the tube after its use is going to be able to react with the product contained in the tube, and does so up to the next use, potentially several hours, days or even weeks later. Moreover, if the product has to be applied to the skin of a user, a risk of bacterial contamination of the product exists on account of the contact of the product with the external air sucked in.
This situation is avoided by placing an air non-return system inside the tube, so as to prevent a return of air inside the tube after use, and thus prevent or considerably reduce the risks of oxidation of the contents of the tube.
An example of such device is illustrated by the document EP0636549.
This document describes a tube for the distribution of a product of fluid to pasty consistency, the tube being composed of a skirt and an upper dome shaped part having an opening, comprising in addition an insert placed at the outlet end of the tube and thereby defining a compartment between said insert and the dome of the tube.
The insert comprises a point that blocks the opening of the tube, and adapted to free said opening thanks to the movement of a deformable wall that deforms under the effect of the accumulation of product in said compartment.
The problem of such a system is its structural and industrialisation complexity as well as its cost. In this respect, such a system comprises several components different to each other that need to be assembled together. On the one hand, each component is manufactured separately, which increases the total cost of the system. Then, the assembly of the components together is particularly difficult given that it takes place in the tube head, the head only having available very little space, of the order of several millimetres, to accommodate said non-return system.
On the other hand, placing said system inside the head necessitates a high degree of manufacturing precision given that a certain sealing needs to be respected to avoid said return of air. This precision also generates a production cost.
DESCRIPTION OF THE INVENTION
The invention proposes a tube head not having these drawbacks.
The invention thus proposes a tube head for product of fluid to pasty consistency comprising



a neck having at a first end an opening through which the product is extracted from the tube,
a shoulder connected to a second end of the neck opposite the first end, and

the tube head comprising an air non-return means placed in said neck, said means being adapted to avoid a return of air from the first end of the neck to the second end of the neck, characterised in that the tube head is one piece




According to particular embodiments, the tube head comprises one or more of the following characteristics, taken independently or in combination:



the non-return means are a grid;
the grid is placed at an intermediate position between the first and the second end of the neck, so that for a neck having a height H, the distance between the grid and the first end of the neck is between H/2 and H;
the grid is placed in a plane substantially perpendicular to an axis of the neck;
the grid comprises at least two orifices of circular section, each of the orifices having a diameter between 0.5 and 2 mm;
the neck has an internal wall having an axis of symmetry, and the orifices of the grid are spread out in a symmetrical manner in relation to the axis of the neck;
the grid has a thickness between 0.5 and 1.5 mm;
the tube head is made of plastic material.



The invention also relates to a tube comprising such a tube head, said tube advantageously comprising a skirt made of at least one plastic or metallo-plastic material, such as polyethylene or polypropylene.
The invention moreover relates to a method of manufacturing a tube head, said method comprising the following steps:



a step of injection of the tube head, so as to form a neck having an opening at a first end, a shoulder connected to a second end of the neck opposite the first end, the shoulder broadening out from the neck, and an internal wall placed in said neck, so as to block it, the tube head being monolithic,
a step of piercing said membrane, so as to form at least one opening in said membrane.






DESCRIPTION OF FIGURES
Other characteristics, aims and advantages of the invention will become clear from the description that follows, which is purely illustrative and non limiting, and which should be read with reference to the appended drawings, in which:
FIG. 1 presents a tube head according to an aspect of the invention;
FIG. 2 presents the tube head illustrated in FIG. 1 associated with a cap;
FIGS. 3 and 4 present two views of another embodiment of tube head according to an aspect of the invention;
FIG. 5 presents a tooling for the formation of a tube head according to an aspect of the invention;
FIG. 6 presents another embodiment of a tube head according to the invention.



DETAILED DESCRIPTION
FIG. 1 presents a sectional view of a tube head according to an embodiment of the invention.
The head 1 comprises:
a neck 2,

a shoulder 3, and

non-return means 4.

The tube head 1 is connected to a skirt 5, of which a part connected to one end of the shoulder 3 is represented.
The skirt 5 delimits one or more reservoirs of products.
The neck 2 comprises a first end 21 provided with an opening 6, and a second end 22 opposite to said first end 21, at which the neck 2 is connected to the shoulder 3.
The neck 2 is conventionally substantially cylindrical or conical around an axis Z or elliptical, so as to enable the closing of the opening 6 via a cap, not represented, which is screwed onto an external threading 23 of the neck 2.
As represented in FIG. 1, the first end 21 of the neck 2 is substantially flat, so as to enable a sealed joint to be formed between the neck 2 and a cap screwed onto said neck 2.
In a variant, a sealing joint may be placed on said first end 21 of the neck.
Other embodiments may be envisaged, especially embodiments in which the tube head 1 comprises a cap commonly called “flip-top” provided with a pivoting cover. The cap is then typically screwed, bonded, welded or force fitted onto the tube head 1, in a position oriented in an adapted manner as a function of the shape of the tube and any inscriptions borne on it.
The shoulder 3 as illustrated extends from the second end 22 of the neck 2, and is splayed from one joint end 31 of the shoulder 3 to a free end 32 of the shoulder 3.
In a variant, the shoulder 3 is substantially flat. The shoulder 3 extends for example from the second end 22 of the neck 2 in a plane perpendicular to the axis Z of the neck 2.
In the embodiment illustrated, the shoulder 3 comprises a stop 33 placed near to its neck end 31, said stop 33 making it possible to form a stop when a cap is screwed onto the neck 2.
This stop 33 thus makes it possible to reinforce the area of the shoulder 3 on which a force is likely to be exerted during the screwing down onto the neck.
The stop 33 typically has a profile comprising one or more circular lips, or is composed of several portions of circle centred on the axis Z of the neck 2.
The shoulder 3 typically comprises a reinforced section 34 at the joint between the tube head 1 and the skirt 5, taking the shape of a section of thickness substantially increased in the embodiment represented in FIG. 1.
The non-return means 4 are a grid placed inside the neck 2.
In the embodiment represented, the grid 4 is placed in a plane substantially perpendicular to the axis Z of the neck 2.
The grid 4 is typically placed substantially at the second end 22 of the neck 2, or more generally at an intermediate position between the first end 21 and the second end 22 of the neck 2.
In the embodiment represented, the grid 4 is fixed in relation to the neck 2. In other words, the grid is not moveable relatively to the neck 2.
The grid 4 is composed of a wall 41 placed in a plane substantially perpendicular to the axis Z of the neck 2, and one or more orifices 42 arranged in said wall 41.
The orifices 42 are situated facing the opening 6 of the neck 2; they have a circular, square, rectangular, triangular or elliptic section, and pass through the wall 41 so as to form a passage between the inside of the tube to which is fixed the tube head 1 and the outside.
The number of orifices 42 is between 3 and 15, preferably equal to 5 or 9.
In the embodiment represented, the grid 4 comprises 9 orifices 42, spread out in a regular manner in relation to the axis Z of the neck 2. According to an advantageous embodiment; the grid 4 comprises a first orifice centred on the axis Z of the neck 2, and eight other orifices regularly spread out around the axis Z of the neck 2.
The dimensions and the spatial distribution of the orifices 42 are adapted to enable a substantially uniform distribution of the product.
More specifically, each of the orifices 42 is going to lead to the formation of a stick of product in the neck 2. The orifices 42 are advantageously dimensioned so that these different sticks of product are mixed in the neck 2, and thereby at the outlet of the neck the product comes out in the form of a single stick of product, occupying the entire opening 6 of the neck 2.
During use of the tube, the user compresses the skirt 5 of the tube in order to extract thereof the product that it contains.
The product present in the skirt 5 of the tube is then directed towards the tube head 1, and comes out of it through the opening 6 of the neck 2 through the orifices 42 of the grid 4.
When the user ceases exerting a compressive force on the skirt 5, it undergoes an elastic recovery to its initial shape, said elastic recovery being more or less important as a function of the material from which the skirt 5 is constituted.
This elastic recovery leads to a backward movement of the product located in the neck 2, which is sucked towards the inside of the tube.
The presence of the grid 4 makes it possible to conserve a volume of product in the neck 2, so as to form a plug of product and thereby prevent air from penetrating into the tube.
Thus, in the presence of said plug of product in the neck 2, the product contained in the tube is preserved from oxidation or contamination by the ambient environment and, in addition, the elastic recovery of the skirt 5 is limited; the skirt 5 is maintained substantially in the shape that it had at the end of use, which enables the user to visualise the quantity of product present in the tube. Also, if the closing cap of the tube is replaced and closed by the user, the product remaining in the tube is perfectly conserved before the next use.
Only a part of this plug of product facing the opening 6 is then exposed to free air and thus is capable of being oxidised, which represents a very small quantity of product given the relatively small dimensions of the neck 2 compared to the tube.
The positioning of the grid 4 inside the neck 2 makes it possible to ensure the formation of said plug of product inside the neck 2. Indeed, when the user has withdrawn the desired quantity of product from the tube and has ceased to exert pressure on the skirt 5, the part of the neck 2 situated between the grid 4 and the first end 21 of the neck 2 is filled with a residue of product.
Part of said residue of product may then be sucked into the tube, the residue of product being sufficient to ensure the formation of the plug of product inside the neck 2.
The grid 4 is thus positioned so as to enable the formation of a sufficient residue of product, as a function especially of the properties of the product contained in the tube, the dimensions of the tube and the neck, and the materials from which are constituted the tube and the tube head 1.
The grid 4 is thus dimensioned while taking into account all or part of the following properties:
the elasticity of the skirt 5,

the viscosity of the product intended to be contained in the tube,

the positioning of the grid 4,

the dimensions of the tube head 1,

the thickness of the grid 4,

the dimensions and the shape of the orifices 42 of the grid 4,

the spatial distribution of the orifices 4.

The following values may be seen in FIG. 1:
D: corresponds to the diameter of the opening 6, in other words the internal diameter of the neck 2;

H; corresponds to the height of the neck 2, in other words the distance between the first end 21 and the second end 22;

Dhead; correspond to the maximum diameter of the tube head 1, in other words the diameter of the tube head at its joint with the skirt 5;

h; corresponds to the thickness of the grid 4;

d; corresponds to the diameter of the orifices 42 of the grid 4;

L; corresponds to the distance between the first end 21 of the neck 2 and the grid 4.

In particular embodiments, the head 1 has measurement lying within the following ranges of values:
D is between 5 and 10 mm; preferably of the order of 5.66 mm or 9.1 mm;

H is between 5 and 10 mm, preferably between 8 and 10 mm;

Dhead is between 20 and 30 mm; preferably of the order of 25 or 30 mm;

h is between 0.5 and 1.5 mm; preferably of the order of 0.75 or 1 mm;

d is between 0.5 and 2 mm; preferably between 0.9 and 1.5 mm, the value of d depending especially on the value of D;

L is between 6 and 12 mm; preferably of the order of 8 mm.

FIG. 2 illustrates a sectional view of the tube head 1 presented previously, on which is placed a cap 7.
The cap 7 comprises a substantially cylindrical or conical body 71, a tapping 72 complementary to the threading 23 of the neck 2 and a piercing tip 73, arranged so that the cap can be screwed onto the neck 2 when it is brought onto the neck 2 via a first end, and so that the piercing tip 73 is inserted inside the neck 2 when the cap 7 is brought onto the neck 2 via a second end opposite to said first end.
As illustrated in FIG. 2, the cap 7 is placed on the neck 2 so that the piercing tip 73 is positioned inside the neck 2, such a configuration being typically used during the first use of the tube in order to pierce a packaging membrane placed in the neck 2 and plugging it in a hermetic manner in order to protect the product that it contains.
FIG. 2 illustrates the positioning of the grid 4 inside the neck 2; this is placed at a sufficient distance from the first end 21 of the neck 2 to enable the piercing tip 73 not to enter into contact with the grid 4 when the cap 7 is thus positioned on the neck 2.
Thus, for a piercing tip 73 having a height P, the grid 4 is placed at a distance P+e from the first end 21 of the neck 2, where e is equal to the minimum gap desired between the grid 4 and the piercing tip 73.
In particular embodiments, P is between 5 and 8 mm, preferably equal to 7.3 mm, and e is between 0.5 and 2 mm, preferably equal to 0.5 or 1.9 mm.
FIGS. 3 and 4 present two sectional views of a variant of the tube head presented in FIGS. 1 and 2.
This variant comprises components in common with the embodiment described previously, which are marked by the same numerical references.
In this variant, the neck 2 has an external wall 25 and an internal wall 26, between which is defined an internal space 27.
The external wall 25 and the internal wall 26 are preferably concentric, centred on the axis Z of the neck 2 or elliptical.
The external wall 25 comprises the threading 23 on its external face, and an external face that is typically cylindrical or conical.
The internal wall 26 is tubular or conical, of axis Z identical to the axis of the neck 2, and is connected by a first end 261 to the external wall 25 via the first end 21 of the neck 2.
The internal wall 26 defines the dimensions of the opening 6 of the neck; typically its diameter in the case of a cylindrical or conical opening 6. The grid 4 is connected to the internal wall 26, and thereby blocks partially the opening 6 that it defines.
In the embodiment represented, the grid 4 is connected to the internal wall 26 at a second end 262 opposite the first end 261.
In the same way as in FIG. 1, FIG. 4 shows the distance L between the first end 21 of the neck and the grid 4, which corresponds for example to the height of the internal wall 25, and which corresponds to the thickness of the internal wall 25.
The thickness ei of the internal wall 25 is between 0.5 and 1 mm; for example equal to 0.75 mm.
The distance L between the first end 21 of the neck and the grid 4, which corresponds for example to the height of the internal wall 25, is for example between 5 and 10 mm, and advantageously equal to 9.2 mm.
The tube head 1 and the skirt 5 may be formed according to several methods.
The tube head 1 is formed by injection of plastic material, for example polyethylene or polypropylene. In a variant, the tube head 1 may also be formed by a material compression method.
The skirt 5 may also be formed by extrusion of plastic material (then known as plastic skirt) or by longitudinal winding and welding of a multi-layer material made of polyethylene, polypropylene or mixture of polyethylene and polypropylene, having or not a metal sheet (then known as metallo-plastic skirt). Such a metallo-plastic structure corresponds to a layer of metallic material such as aluminium, covered by one or more layers of plastic materials.
The tube head 1 is then for example
either directly overmoulded on the skirt 5, this overmoulding operation being advantageously carried out directly after the formation of the skirt 5, for example on a same production site or on a same production line;

or formed independently of the skirt 5, then assembled on the skirt 5, typically by welding or bonding.

The tube head 1 may have from its manufacture the orifices 42 of the grid 4, or said orifices 42 may be formed during an additional step of machining following the injection of the tube head 1.
The tube head 1 is thus monolithic; it is formed of a single piece, and thus does not required additional steps of positioning the different components in relation to each other.
The neck 2, the shoulder 3 and the air non-return means 4 form a one piece unit. The one piece, or monolithic, character of the tube head 1 does not imply that it is formed of a single material. For example, the shoulder 3 and the neck 3 may be formed of polyethylene, and the air non-return means of elastomeric material. In this case, the tube head 1 forms a one piece unit constituted of two chemically different materials, linked by chemical bonding without requiring mechanical assembly or joint.
The air non-return means 4 are then typically formed by injection moulding.
The skirt 5 of the tube is for example composed of all or part of the following materials: of polyethylene especially in its high, medium and low density variants, of polypropylene, said two polymers being able to be associated with a metal sheet, and typically has the following dimensions:
a thickness between 150 and 250 μm; more specifically between 200 and 250 μm, for example between 225 and 235 μm; typically of the order of 230 μm;

a diameter between 1 and 8 cm; for example between 2 and 5 cm;

a length between 5 and 20 cm, for example between 8 and 16 cm, typically of the order of 12 cm.

A skirt 5 having such characteristics has a low elastic recovery after its compression by the user, and thus makes it possible to optimise the air non-return effect in combination with the air non-return means 4.
High density polyethylene (HDPE) is defined by a density greater than or equal to 0.941 g/cm3. HDPE has a low degree of branching, and thus strong intermolecular forces, and a high tensile strength.
Medium density polyethylene (MDPE) is defined by a density between 0.926 and 0.940 g/cm3.
Linear low density polyethylene (LLDPE) is defined by a density between 0.915 and 0.925 g/cm3. LLDPE is a substantially linear polymer, with a high number of short branches, which is normally formed by copolymerisation of ethylene with short chain alpha-oleins (for example 1-butene, 1-hexane or 1-octene).
Low density polyethylene (LDPE) is defined by a density between 0.910 and 0.926 g/cm3. LDPE has a high level of branching of short and long chains, which implies that the chains are not well contained in the crystalline structure, and results in a lower tensile strength and a more ductile material.
Very low density polyethylene (VLDPE) is defined by a density between 0.880 and 0.915 g/cm3.
The methods for producing these different types of polyethylene are well known from the prior art.
FIG. 5 illustrates an example of tooling for the formation of the tube head 1 as presented in FIGS. 3 and 4.
In this embodiment, the tooling comprises a mould in three parts 81, 82 and 83, as well as a slide 84 adapted to define the internal part of the neck 2, and having lugs 85 forming the orifices 42 of the grid 4.
In a variant, the slide 84 does not comprise lugs 85, and the grid is then initially formed in the form of an internal wall totally blocking the neck 2.
The orifices 42 of the grid 4 are formed later by machining of this internal wall, typically by means of a tool comprising several piercing heads so as to form the set of orifices 42 in a single operation.
FIG. 6 presents a variant of the tube head 1 illustrated in FIGS. 3 and 4.
In this variant, as in the variant presented in FIGS. 3 and 4, the neck 2 has an external wall 25 and an internal wall 26, between which is defined an internal space 27.
The neck is plugged by a solid membrane 29 in place of the grid 4 of the preceding embodiments.
Openings 28 are then made in the internal wall 26 of the neck 2, said openings 28 enabling the channel of the neck to be connected to the internal space 27.
The openings 28 are arranged regularly on the internal wall 26 of the neck 2, for example according to a radial distribution in a plane perpendicular to the axis 2. In another variant, the openings 28 are arranged in the lower part of the internal wall 26. The openings 28 are arranged in the neck 2 so as to meet the same criteria as defined previously for the embodiments illustrated in FIGS. 1 to 4.
In these variants, the product contained in the tube accumulates in the internal space 27 when the user exerts pressure on the skirt 5 of the tube, and is thereby extracted towards the channel of the neck in order to come out through the opening 6 of the tube head 1.
In the embodiment represented in FIG. 6, the tube head 1 is associated with a flip-top type cap 9. The cap 9 as represented comprises a base 91 which is assembled on the first end 21 of the neck, for example screwed, bonded, welded or force fitted, a hinge 92 and a lid 93, connected to the base 91 via the hinge 92. The base 91 of the cap 9 and the neck 2 of the tube head 1 then comprises complementary ratchet means.
In this particular embodiment, the neck 2 then does not necessarily comprise threading 23 as in the embodiments presented in the preceding figures. It will be easily understood that this structure of the tube head 1 comprising an external wall 25 and an internal wall 26 may also be associated with a cap that is screwed onto the neck 2, which then comprises a threading at the external face of its external wall 25.
An embodiment may also be envisaged combining the grid 4 presented in FIGS. 3 and 4 with the openings in the internal wall 26 of the neck 2 presented in FIG. 6, in order to facilitate the outflow of the product contained in the tube by multiplying the openings.
The invention thus makes it possible to form a tube head 1 comprising air non-return means 4 formed of the same material as the tube head 1, and making it possible to preserve the product contained in the tube associated with the tube head 1 without requiring complex and costly manufacturing steps.



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