EP3849921B1 - Valve seal and metering valve for fluid product dispenser - Google Patents

Description

The present invention relates to a valve seal, a metering valve and a fluid dispenser.

The preferred field of application for such a valve is pharmaceuticals, but this type of valve can also be used in other fields, for example cosmetics or perfumery.

Prior art metering valves include a valve body defining a metering chamber in which a valve slides between rest and actuation positions. The valve body and the valve are usually made by molding plastic materials of the polymer type, such as for example polyacetal (POM) or polybutylene terephthalate (PBT). Seals, including an outer seal called a neck seal and two inner seals called a valve seal and a chamber seal, are generally provided in a metering valve. The seals are generally made of elastomeric material, such as for example nitrile, ethylene-propylene-diene monomer (EPDM) or elastomeric cyclic olefin copolymer (elastomeric COC).

The use of such seals can pose several problems. Thus, during their manufacture, it is necessary to add talc to the elastomer strips to prevent sticking during storage. In addition, for the assembly of the valves, it is necessary to use silicone when buffering the joints. In addition, in use, the friction generated between the valve and the internal seals can lead to blockages of the valve, a phenomenon known as “sticking”. In an attempt to overcome or limit these problems, it has been proposed to use elastomeric materials to which lubricants are added, also called slip agents, generally based on silicone, erucamide, oleamide. These additives migrate to the surface of the material, thus reducing its coefficient of friction and consequently improving its resistance to friction. However, it is not always easy to control this lubrication. Additives, before they can fulfill their role as agents lubricants in the elastomer matrix, can be degraded during the manufacture of the material. There may also be interactions with other ingredients present in the elastomeric matrix. This is particularly the case in the presence of mineral fillers, which can absorb these lubricants, thus preventing their migration to the surface of the material.

The documents WO0056632 and US6843392 describe devices of the state of the art.

The present invention aims to overcome the aforementioned problems.

The object of the present invention is thus to provide a valve seal with improved friction properties.

The present invention also aims to provide a valve seal, a metering valve and a fluid dispenser device that are simple and inexpensive to manufacture and assemble.

The present invention therefore relates to a valve gasket for a metering valve of a fluid dispenser, said gasket being made of a self-lubricating elastomeric material, said elastomeric material containing a lubricant, such as silicone oil, said lubricant being encapsulated in the form of microcapsules and/or microspheres, which are added to the elastomeric material of the gasket.

Advantageously, the elastomeric material comprises EPDM.

Advantageously, the lubricant comprises silicone oil.

Advantageously, microcapsules and/or microspheres containing silicone oil are added to the elastomeric material during manufacture of the gasket.

Advantageously, the quantity of said microcapsules and/or microspheres introduced into the elastomeric material is less than 5% by weight, advantageously around 3% by weight of the elastomeric material.

The present invention also relates to a metering valve of a fluid dispenser, comprising a valve body defining a metering chamber in which a valve slides between rest and actuation positions, said valve comprising a neck seal and at at least one internal seal, said valve sliding against said at least internal seal, said metering valve comprising at least one seal as described above.

Advantageously, said at least one internal seal is made as described above.

The present invention also relates to a fluid dispenser, comprising a reservoir containing the fluid to be dispensed, said dispenser comprising a metering valve as described above.

Advantageously, the dispenser comprises an HFA gas as propellant gas.

• La figure 1 est une vue schématique en coupe d'une valve doseuse selon un mode de réalisation avantageux,
• La figure 2 est un graphique comparant le Module à 100% de déformation d'un joint EPDM, avec ou sans silicone, avec un joint EPDM comportant des microcapsules ou des microsphères selon l'invention,
• La figure 3 est un graphique comparant la dureté Shore A d'un joint EPDM, avec ou sans silicone, avec un joint EPDM comportant des microcapsules ou des microsphères selon l'invention, et
• La figure 4 est un graphique comparant le coefficient de frottement par rapport au POM et au PBT d'un joint EPDM, avec ou sans silicone, avec un joint EPDM comportant des microcapsules ou des microsphères selon l'invention.

These characteristics and advantages and others will appear more clearly during the following detailed description, made with reference to the attached drawings, given by way of non-limiting examples, and in which:

• The figure 1 is a schematic sectional view of a metering valve according to an advantageous embodiment,
• The picture 2 is a graph comparing the Modulus at 100% deformation of an EPDM seal, with or without silicone, with an EPDM seal comprising microcapsules or microspheres according to the invention,
• The picture 3 is a graph comparing the Shore A hardness of an EPDM seal, with or without silicone, with an EPDM seal comprising microcapsules or microspheres according to the invention, and
• The figure 4 is a graph comparing the coefficient of friction with respect to POM and PBT of an EPDM seal, with or without silicone, with an EPDM seal comprising microcapsules or microspheres according to the invention.

In the following description, the terms "up" and "down" refer to the upright position represented on the figure 1 , and the term "radial" refers to the longitudinal axis of the valve shown in the figure 1 .

The metering valve represented on the figure 1 is of the retention type. It is however understood that this is only an example, and that the present invention applies to all types of metering valves. More generally, the present invention could also be applied to pump seals not using propellant gas for the distribution of the fluid product.

The valve of the figure 1 comprises a valve body 10 extending along a longitudinal axis. Inside said valve body 10, a valve 30 slides between a rest position, which is that shown in the figure 1 , and a dispensing position, in which the valve 30 is pushed inside the valve body 10.

This valve is intended to be assembled on a tank 1, preferably by means of a fixing element 5, which can be a cap to be crimped, screwed or snapped on, and advantageously with the interposition of a neck gasket 6. Optionally, a ring 4 can be assembled around the valve body, in particular to reduce the dead volume in the inverted position and to limit the contact of the fluid product with the neck seal. This ring can be of any shape, and the example of the figure 1 is not limiting.

The valve 30 is biased towards its rest position by a spring 8, which is arranged in the valve body 10 and which cooperates on the one hand with this valve body 10, and on the other hand with the valve 30, preferably with a radial flange 320 of the valve 30. A metering chamber 20 is defined inside the valve body 10, said valve 30 sliding inside said metering chamber to allow the contents of the latter to be dispensed when the valve is actuated.

The metering chamber is preferably defined between two annular seals, a valve seal 21 and a chamber seal 22, in a well-known manner.

The figure 1 represents the valve in the upright storage position, that is to say the position in which the metering chamber 20 is arranged above the reservoir 1.

The valve 30 has an outlet orifice 301 connected to an inlet 302, which is disposed in the metering chamber 20 when the valve 30 is in the dispensing position. The valve 30 can be made in two parts, namely a top part 31 (also called top of valve) and a lower part 32 (also called lower valve). The lower part 32 is in this embodiment assembled inside the upper part 31. An internal channel 33 is provided in the valve 30 which makes it possible to connect the metering chamber 20 to the tank 1, to fill said metering chamber 20 when, after each actuation of the valve, the valve 30 returns to its rest position under the effect of the spring 8. This filling is done when the device is still in the inverted position of use, with the valve arranged below of the tank.

Typically, the metering valve contains a propellant gas, in particular of the well-known HFA type.

According to the invention, at least one seal of the valve, in particular at least one internal seal 21, 22, is made of a self-lubricating elastomeric material, a lubricant, such as silicone oil, being encapsulated in the form of microcapsules and / or microspheres, which are added to the elastomeric material of the gasket. This microencapsulation makes it possible to control and/or trigger the lubricating action at well-defined stages of the manufacturing process and/or during the operation of the product.

• la microcapsule, qui peut être assimilée à un réservoir emprisonnant une matière active liquide (plus ou moins visqueuse) ;
• la microsphère, qui est un réseau macromoléculaire qui ressemble à de petites poches remplies de matières actives (à l'image d'une éponge).

Microencapsulation makes it possible to imprison liquids or solids in a polymer membrane in order to protect them from the external environment or to control their release into a chosen environment. Depending on the preparation technology used and the final need, it is possible to obtain two types of products:

• the microcapsule, which can be likened to a reservoir trapping a liquid active ingredient (more or less viscous);
• the microsphere, which is a macromolecular network that looks like small pockets filled with active materials (like a sponge).

The release of the active principle can be done in several ways. It can be sudden, under the effect of a constraint such as heat or pressure in the case of microcapsules. The microspheres make it possible to have a gradual release of the encapsulated product. Eventually, we can consider combining the two effects, simultaneously adding microcapsules and microspheres.

The size of the microcapsules and/or microspheres can vary between 5 and 100 μm.

In the examples described below, microcapsules or microspheres of silicone oil were introduced at a level of 3% by weight into the EPDM material forming a valve seal. The mode of addition is done as for the other ingredients (mineral fillers, antioxidant, vulcanizing agent, etc.) usually added in an EPDM material.

Advantageously, an amount which is less than 5% by weight is provided.

• EPDM standard;
• EPDM standard + 3% d'huile de silicone ajoutée.

The properties of the materials obtained were compared with two controls:

• Standard EPDM;
• Standard EPDM + 3% added silicone oil.

The figure 2 illustrates the Modulus at 100% strain, and the picture 3 the Shore A hardness. It can be seen that the addition of microcapsules and microspheres has no negative impact on these mechanical properties of the elastomer, here EPDM.

The figure 4 illustrates the coefficient of friction for these same materials, on the one hand on POM and on the other hand on PBT.

The test consists of rubbing the EPDM on plastic materials (POM & PBT) in order to determine a coefficient of friction.

The coefficient of friction is the ratio of the traction force (response force allowing the device to move) to the force applied (normal force).

• Le coefficient statique est le coefficient mesuré en début de test. C'est la force nécessaire pour déplacer l'échantillon sur le substrat et initier le mouvement. On parle aussi de coefficient d'adhérence ;
• Le coefficient dynamique est le coefficient nécessaire pour que le mouvement soit maintenu à une vitesse constante.

There are two types of coefficients: a dynamic and a static.

• The static coefficient is the coefficient measured at the start of the test. It is the force required to move the sample on the substrate and initiate movement. We also speak of adhesion coefficient;
• The dynamic coefficient is the coefficient necessary for the movement to be maintained at a constant speed.

For the present comparison, the values of the dynamic coefficient were used, with the stable system and at constant speed.

With the simple addition of silicone in the formulation, there is no improvement in friction. This confirms the hypothesis of the absorption of the silicone by the elastomer matrix in this case.

On the other hand, a reduction in the coefficient of friction is observed for all the configurations with microcapsules or microspheres according to the invention.

The results obtained demonstrate that the addition of microcapsules or microspheres makes it possible to significantly reduce the coefficient of friction.

The comparative tests were carried out with EPDM seals, but the same result will be obtained with other elastomeric materials used for the manufacture of valve seals.

The encapsulation of the lubricant makes it possible to confine it to prevent it from being absorbed or degraded during the manufacturing process of the material. In addition, it makes it available on the surface of the material when the microcapsules break under mechanical stress, by friction or pressure.

The invention therefore makes it possible to reduce the problems of friction in the valves, and therefore to eliminate or at least limit the risks of sticking. In addition, the addition of talc to the elastomer strips to avoid stickiness during storage is no longer necessary, which makes it possible to reduce the manufacturing costs of the seals, and therefore of the valve. The assembly of the valves is also simplified by the reduction or elimination of the use of silicone when buffering the joints.

The present invention has been described with reference to an advantageous embodiment, but it is understood that a person skilled in the art can make any modifications thereto, without departing from the scope of the present invention as defined by the appended claims.

Claims (9)

1. A valve gasket (21, 22) for a metering valve of a fluid dispenser, made of an elastomer material that is self-lubricating, said elastomer material containing a lubricant, such as silicone oil, characterized in that said lubricant is encapsulated in the form of microcapsules and/or microspheres, that are added to the elastomer material of the gasket.
2. A gasket according to claim 1, wherein the elastomer material comprises EPDM.
3. A gasket according to any preceding claim, wherein the lubricant comprises silicone oil.
4. A gasket according to any preceding claim, wherein microcapsules and/or microspheres containing silicone oil are added to the elastomer material while the gasket is being manufactured.
5. A gasket according to claim 4, wherein the quantity of said microcapsules and/or microspheres introduced into the elastomer material is less than 5% by weight, advantageously about 3% by weight, of the elastomer material.
6. A metering valve of a fluid dispenser, the metering valve comprising a valve body (10) that defines a metering chamber (20) in which a valve member (30) slides between a rest position and an actuated position, said valve including a neck gasket (6) and at least one internal gasket (21, 22), said valve member sliding against said at least one internal gasket (21, 22), said metering valve being characterized in that it includes at least one gasket according to any preceding claim.
7. A valve according to claim 6, wherein said at least one internal gasket (21, 22) is made according to any one of claims 1 to 6.
8. A fluid dispenser comprising a reservoir (1) containing fluid to be dispensed, said dispenser being characterized in that it includes a metering valve according to claim 6 or claim 7.
9. A dispenser according to claim 8, containing a HFA gas as a propellant gas.

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