Patent Description:
Membrane-based air fresheners have become an increasingly popular alternative for providing controlled dispensing of volatile substances into the ambient air. Among many other examples, <CIT> discloses a dispensing system based on permeable membranes which is attachable to a frame and comprises a plurality of protrusions that prevent excessive gas concentration in delicate surface. <CIT> presents a foldable laminar element with a dispensing membrane and a hook that enables various configurations for the installation of the device. Finally, <CIT> discloses a device which relies on an external air current, such as a car ventilation outlet to enhance evaporation and diffusion of the volatile substance through the membrane.

Most common system are based on a polyolefin monolithic membrane, that is, a non-microporous membrane, which is provided in a multi-layer structure together with a barrier material. The multilayer is sealed on the container containing the fragrance in a single step, and the barrier is removed by pealing by the user. This approach is easy to fabricate, but presents limited efficiency and is only compatible with certain kinds of perfumes. Nevertheless, the low permeability of the fragrance through the membrane advantageously enables the perfume to pass through the thin membrane wall but not through the sealing flange (typical thickness around <NUM> to <NUM>). This prevents evaporation during the storage of the product.

Membranes with higher transportation rates have also been proposed. However this also implies a higher transportation rate through the sealing flanges. Therefore, during storage, slight evaporation may occur through the perimeter of the membrane. This is the case of recently-developed microporous systems, working by capillarity. The perimetral flange is able to transport the volatile substance without any limitations along distances of several millimetres, the perimetral flange hence becoming a quite open system which cannot guarantee refill stability (i. e, absence of weight loss) during storage.

<CIT> discloses a membrane device including one or more membrane layers which are permeable to the volatile composition and which are positioned within a vapor impermeable package such as package formed by an upper and lower vapor impermeable panel. The upper vapor panel includes a window that allows access to the membrane layer for activation of the membrane device.

Therefore, there is still the need of membrane-based volatile substance dispersers and refills, which can provide high transportation rates while preventing perimetral leakage of the produce.

The current invention solves the aforementioned problems by disclosing a membrane-based volatile substance dispenser, such as an air-freshener refill, with perimetral cleavages for preventing evaporation of the produce through the laterals of the device.

The invention is defined in the attached claims.

A volatile substance dispensing device is disclosed comprising a container of the volatile substance, preferably thermoformed, sealed by a multilayer structure comprising the following:.

Two preferred options for the blocking means are disclosed:.

A fabrication method of a volatile substance dispenser is disclosed, comprising the following steps:.

More preferably, a transversal cut may be performed through the polymeric resin, said cut defining the edge of the dispenser. Also preferably, a plurality of dispensers may be positioned adjacently during fabrication, sharing the same material layers, and being later separated by the transversal cut performed through the polymeric resin. In a second preferred option, the filling step comprises melting the separation layer by applying heat and pressure during welding, until said separation layer partially or fully fills the cleavage.

Notice that any preferred option or particular embodiment of the device of the invention may be applied to the method of the invention and viceversa.

The described device and method of the invention provide membrane-based volatile substance dispensing with high transport rates and safe storage without perimetral evaporation. They also provide easy fabrication and use, as well as a robust structure. These and other advantages will become apparent in the light of the detailed description of the invention.

For the purpose of aiding the understanding of the characteristics of the invention, according to a preferred practical embodiment thereof and in order to complement this description, the following figures are attached as an integral part thereof, having an illustrative and non-limiting character:.

The matters defined in this detailed description are provided to assist in a comprehensive understanding of the invention. Accordingly, those of ordinary skill in the art will recognize that variation changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. Also, description of well-known functions and elements are omitted for clarity and conciseness.

Note that in this text, the term "comprises" and its derivations (such as "comprising", etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc..

<FIG> shows a frontal view a preferred embodiment of the volatile substance dispensing device <NUM> of the invention comprising a single perimetral cleavage <NUM>, located on top of the perimetral welding flange <NUM> of the thermoformed device. The cleavage <NUM> follows a closed continuous line in the external region of the device <NUM>, close to the border of said device <NUM> but maintaining at least some margin from said border. That is, the membrane layer is present on both sides of the cleavage <NUM>. Notice that the particular geometry of the cleavage <NUM> may vary depending on the particular shape of the device and particular design choices. The cleavage <NUM> preferably occupies the full thickness of the membrane layer, although particular embodiments with a cleavage <NUM> only partially cutting the membrane thickness may be implemented. Furthermore, several concentric cleavages may be included in a single device, as exemplified by <FIG>, hence further reducing liquid transport along the welding flange during storage and consequent weight loss.

<FIG> presents a lateral view of the dispensing device <NUM> during fabrication by heat welding. Two separate parts are provided, namely a thermoformed container <NUM> and a multilayer element comprising a membrane layer <NUM>, a separation layer <NUM> and a removable barrier layer <NUM>. A welding tool <NUM> for fixing both parts together is also represented.

The thermoformed container <NUM> may be implemented by combining a PET (Polyethylene terephthalate) layer <NUM> and a PE (Polyethylene) layer <NUM>. The container <NUM> stores the volatile substance in liquid form for its progressive dispensing through the membrane layer <NUM>, preventing its diffusion through any other surface of the device <NUM>.

The membrane layer <NUM> may be implemented with different alternative technologies:.

The cleavage <NUM> is preferably performed by laser cutting, although other cutting techniques known in the state of the art may be used. The cleavage preferably has a width between <NUM> to <NUM>. The cleavage <NUM> is later filled with a polymeric material having low transport capacity of the volatile substance.

In this case, the separation layer <NUM> is made from a thermoplastic material having a reduced adhesion to the membrane layer <NUM>, which melts when heat is applied. The thickness of the separation layer <NUM> is at least equal to the thickness of the membrane layer <NUM> and is preferably higher than said thickness of the membrane layer <NUM>. Notice that the term "reduced" in this context should be understood as that the strength of adhesion between separation layer <NUM> and the membrane layer <NUM> is high enough to stay in place during storage and before first use, but low enough to allow separation when a user manually pulls from the barrier layer <NUM>. The mechanical resistance of the adhesion between membrane layer <NUM> and separation layer <NUM> shall be lower than the mechanical resistance of the membrane layer <NUM> and barrier layer <NUM>, and shall be low enough to circumvent the need of any external tool to separate the layers.

The barrier layer <NUM> preferable comprises a material having high barrier properties to the volatile substance, such as an aluminium layer <NUM>, and a plastic layer <NUM> for mechanical reinforcement, such as PET.

The welding tool <NUM> is adapted to heat and melt the separation layer <NUM> during the welding process. In this molten state, the material of the separation layer <NUM> can flow and substantially fill the gap of the membrane layer <NUM>. Furthermore, the welding tool <NUM> presents a protrusion with a higher depth in an area substantially corresponding to the cleavage <NUM> in order to force the material in that area to flow better and fill better the gap in the membrane layer <NUM>. By "substantially", it should be understood that the extra depth in the welding tool <NUM> falls inside the gap in the membrane during the welding process. So for example, for a gap of <NUM>, with a machine that has a positioning precision of <NUM>, the maximum extra depth in the welding tool shall be <NUM> in order to always fall inside the gap. Although the cutting of the membrane and the filling of the resulting gap can be done in an offline process, it may be advantageously done during a Form Fill Seal process.

<FIG> presents the device <NUM> resulting from the fabrication process presented in <FIG>, according to particular embodiments of the device and method of the invention. After heat welding and melting of the separation layer <NUM>, the protrusion <NUM> of said separation layer <NUM> now fills the cleavage <NUM>, preventing lateral diffusion of the volatile substance. A welding flange <NUM>, for example of <NUM>, is finally performed on the refill.

As a non-limiting example, some particular materials and dimensions for this options are hereby provided. Thermoformed container <NUM> is based on PET/EVOH/PE with a thickness of <NUM> (EVOH: Ethylene vinyl alcohol). Membrane layer <NUM> is a Polyethylene microporous of <NUM> thickness. Separation layer <NUM> is a <NUM>-µm-thick PP layer. Barrier layer <NUM> comprises a <NUM>-µm-thick Aluminium layer and a <NUM>-µm-thick PET layer. PE membrane is cut by a laser to a width of <NUM>. Laser is set to cut precisely the depth of the PE membrane.

<FIG> exemplifies an alternative fabrication method in which the plastic material that fills the cleavage <NUM> is a polymeric resin <NUM>. In this case, the separation layer <NUM> is preferably implemented with a paper layer. A ribbon of resin <NUM> is applied in the cleavage <NUM> created by the cut. Polymeric resin application may be carried out, for example, by a motorised three-axis nozzle. The width of the ribbon is preferably slightly wider that the cleavage <NUM> cut in the membrane (for example a <NUM> ribbon for a <NUM> cut). The polymeric resin <NUM> is preferably of the kind of epoxy or acrylic glue, UV curable. An UV light is applied to the glue between application of the glue and welding of the multilayer structure on the thermoformed container <NUM>. Optionally, a second dose of UV can be applied after the welding to complete glue curing.

<FIG> shows the resulting device of <FIG> after joining the multilayer structure to the container <NUM>. As a non-limiting example, some particular materials and dimensions for this options are hereby provided. Membrane layer <NUM> is a microporous UHMWPE (Ultra-high-molecular-weight polyethylene) with a thickness of <NUM>. Said membrane layer <NUM> is laminated or glued to a paper layer of <NUM> gsm (Grams per Square Meter), which is also glued on the other side to a <NUM> Aluminium <NUM> PET layer. The glue used is a polyurethane reactive hotmelt with a dosage of <NUM> gsm. Microporous UHMWPE is cut in a continuous line of <NUM> width by a laser. The laser cut goes through the whole membrane thickness and also through the paper layer.

<FIG> presents an alternative embodiment of the fabrication method of the invention, resulting in a subsequent alternative embodiment of the device of the invention. In this case, after filling the cleavage <NUM> with the polymeric resin <NUM> (and curing if necessary), a transversal cut <NUM> is performed through the whole thickness of the device <NUM> at the position of said polymeric resin <NUM>. Therefore, the transversal cut <NUM> determines the edge of the device <NUM>, and reduces the size of the device <NUM> by removing all layers outside the cleavage <NUM>. In case of multiple cleavages <NUM>, the transversal cut <NUM> is performed across the outermost cleavage <NUM>. This process is also illustrated in <FIG>, where the remaining materials of the device <NUM> outside the dashed line of the transversal cut <NUM> are discarded.

Claim 1:
Fabrication method of a volatile substance dispensing device (<NUM>) comprising:
- welding a membrane layer (<NUM>), a separation layer (<NUM>) and a removable barrier layer (<NUM>) onto a container (<NUM>) of the volatile substance; being the membrane layer (<NUM>) adapted to progressively diffuse the volatile substance into ambient atmosphere; and preventing the barrier layer (<NUM>) the diffusion of the volatile substance;
characterized in that the method further comprises:
- cutting at least one perimetral cleavage (<NUM>) in the membrane layer (<NUM>); and
- filling at least partially the at least one perimetral cleavage (<NUM>) with plastic blocking means preventing the diffusion of the volatile substance.