Device for diffusion of volatile substances

A device for diffusion of volatile substances that includes a container for containing volatile substances, including the container, an aperture defining a sealing area, and a multilayer structure placed on the aperture. The multilayer structure includes a microporous membrane through which the volatile substances are diffused and a barrier layer that is removed before a first use. The multilayer structure also includes a sealing portion in contact with the sealing area. A device with a microporous membrane where the porosity of the membrane at the portion of the sealing area has been substantially reduced or eliminated to stop liquid transportation.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§ 371 national phase patent application based on PCT/EP2018/086255, filed Dec. 20, 2018, which claims priority to European Patent Application No. 17210018.2, filed Dec. 22, 2017, the entire contents of both applications being incorporated herein by reference. The PCT International Application was published in the English language.

The present invention refers to a device for diffusion of volatile substances, comprising a container with a sealing area, that guarantees a better stability during its storage.

BACKGROUND OF THE INVENTION

Membrane air fresheners have been growing a lot in the air freshener market.

Most common system are based on polyolefin monolithic membrane (i.e. non-microporous) that gives an acceptable behavior but has limited efficiency and also limits a lot the kind of volatile substances or perfume that can be used.

This kind of membrane is very easy to produce as the membrane comes in a multilayer structure together with a barrier material. The multilayer is sealed on an aperture of a container containing the volatile substances or fragrance in a single step. Before a first use, the barrier is removed by pealing by the user.

Several intents have been done in using membrane with a much higher transportation rate of fragrances. The issue here is that if the transportation through the membrane wall is higher, it is also higher through the sealing area defined in the aperture of the container, and thus during storage we observe that the portion of the membrane in contact with the sealing are is evaporating slightly.

A special kind of recently implemented membranes are microporous systems. Being a micro porous system that works by capillarity, the portion in contact with the sealing are is able to transport the liquid without any limitations along distances of several millimeters, and so the sealing area is a quite open system, that is a problem to guarantee refill stability during storage.

Therefore, it is evident the need of a device for diffusion of volatile substances, comprising a container with a sealing area, that guarantees a better stability during its storage.

DESCRIPTION OF THE INVENTION

With the device according to the invention said drawbacks can be solved, presenting other advantages that will be described hereinafter.

The device for diffusion of volatile substances according to present invention comprises:a container for containing volatile substances, including the container an aperture defining a sealing area; anda multilayer structure placed on said aperture, said multilayer structure comprising a microporous membrane through which the volatile substances are diffused and a barrier layer that is removed before a first use;
wherein said multilayer structure also comprises a sealing portion in contact with said sealing area.

Advantageously, said sealing portion is made from a polymeric material, such as e.g. from thermoset resin or thermoplastic, and it is preferably welded to said sealing area.

Furthermore, the material of said sealing portion is introduced into the pores of the microporous membrane in a pattern corresponding to the sealing area, sealing these pores.

According to a preferred embodiment, said sealing area is a perimetric flange in the perimeter of said aperture of the container.

Furthermore, preferably said multilayer structure also comprises a separation layer than is placed between the barrier layer and the membrane, and that is removed before a first use.

Said barrier layer can be made from metal or plastic, and said separation layer can be made from paper or plastic.

According to the invention, it is provided a device with a microporous membrane where the porosity of the membrane at the portion of the sealing area has been substantially reduced or eliminated to stop liquid transportation.

DESCRIPTION OF A PREFERRED EMBODIMENT

The device according to the present invention comprises a container1, preferably thermoformed, filled with the volatile substances, such as a liquid.

The container1includes an aperture2defining a sealing area3, such as e.g. a perimetric flange.

On this aperture2a multilayer structure4is placed, e.g. by welding, preferably heat welding. This multilayer structure4comprises, according to the shown embodiment, a barrier layer41, a microporous membrane42and a separation layer43, which is interposed between the barrier layer41and the separation layer43.

Before a first use, user removes the barrier layer41by pealing it, and the barrier layer41separates from the membrane42thanks to the separation layer43.

Preferably, the separation layer43is a layer with low internal cohesive mechanical resistance and will separate along its thickness, remaining part of this layer43on the membrane42and part on the barrier layer41. E.g., the separation layer43can be a paper layer. Alternatively, the separation layer43can be made from a plastic having a reduced adhesion on the membrane.

By “reduced” it is understood that the strength of adhesion between separation layer43and the membrane42is high enough to keep it in place during storage and before first use, but low enough to allow the separation when user pull the barrier layer41and the separation layer43of the multilayer structure4.

It will be clear for a person skilled in the art that the mechanical resistance of the adhesion between membrane42and separation layer43shall be lower than the mechanical resistance of the membrane42and of the barrier layer41and it will be low enough to not require an external tool to separate the layers.

The membrane42is made of a microporous membrane, e.g. made of polyethylene, polypropylene, ultra-high molecular weight polyethylene, or polytetrafluoroethylene, although it will be clear that any known microporous material can be used.

The barrier layer41is made from a material having high barrier properties to the volatile substance, preferably aluminium, and a plastic layer to reinforced mechanically, preferably a PET layer.

This multilayer structure4comprises also a sealing portion44in correspondence with the sealing area3in order to improve the refill integrity during storage by reducing liquid transportation along the plane of the multilayer structure4.

This sealing portion44can be a ribbon of polymeric material on the membrane42side of the multilayer structure4in an area that will be placed in coincidence with the sealing area3of the container1to be made with that membrane42.

The polymeric material of the sealing portion44penetrates into the pores during the attachment of the multilayer structure4to the container1, and then the polymeric material solidifies.

Two main options exist to implement the invention, that differs mainly of the kind of polymeric material that is used for the sealing portion44, that can be a thermoset resin or a thermoplastic resin.

If the sealing portion44is a thermoset resin, it is applied in liquid state on the surface of the membrane42in an area that will later corresponds to the sealing area3of the container1.

Depending of the viscosity of that resin, it may be able to penetrate inside the membrane42without the need to apply a certain pressure on it. Alternatively, the material penetration through the membrane42can be forced by applying a mechanical stress on the sealing portion44. This could be achieved by calendaring the membrane42after the deposition of the sealing portion44.

As an example, the container1can be made from PET/EVOH/PE with a thickness of 500 microns, and the multilayer structure4can be made of a membrane42of microporous polyethylene with a thickness of 50 microns, a separation layer41with a thickness of 100 microns of PP, and on top of the PP layer an aluminium sheet of 20 microns of thickness and a PET sheet with a thickness of 20 microns (external side).

The thermoset sealing portion44is deposed on the external side of the membrane42along a pattern. The width of the sealing portion44is 1 mm and its thickness is 0.2 mm

The thermoset material 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 the welding of the multilayer structure41on the container1. It would be clear for a person skilled in the art that any known thermoset having the sufficient chemical resistance to the volatile substances to be diffused can be used.

Optionally, a second dose of UV can be applied after the welding to complete the glue curing. A welding flange of 5 mm, corresponding to the sealing area3, is scheduled to be done on the final device.

According to a second example, the membrane42can be a microporous UHMWPE layer with a thickness of 200 microns. It is laminated/glued on a paper separation layer43of 40 GSM, that is also glued on the other side to a barrier layer41made of aluminium (20 microns) and PET (20 microns). The glue used can a polyurethane reactive hotmelt with a dosage of 15 GSM.

On the membrane side of this multilayer structure4, a sealing portion44of thermoplastic material is applied. The material of the sealing portion44is preferably a polyolefin, and more preferably a polypropylene, although it would be clear for a person skill in the art that any alternative material can be used, with the limitation of having a sufficient chemical resistance in front of the substance that will be contained in the container and of having a melting range close to the temperature needed to be applied to seal the membrane42on the container1.

The sealing portion44is applied following a closed pattern, corresponding to the sealing area3, similar to the welding flange geometry of the container1where the multilayer structure4will be welded.

Preferably, the sealing portion44is not wider than the welding flange, but alternatively, the projection of the sealing portion44extends beyond what will be the welding flange of the container1sealed.

During the welding process of the multilayer structure4on the container1, the sealing portion44is molten due to the heat of the welding tool and force to penetrate inside the microporous membrane42due to the pressure of the welding.

The result of this process is that the microporous membrane42is not anymore microporous in the sealing area3but is a heterophasic layer (membrane material+sealing portion material), avoiding transportation of the liquid.

Even though reference is made to a specific embodiment of the invention, it is apparent for a person skilled in the art that the device is susceptible of numerous variations and modifications, and all the details cited can be substituted by other technically equivalent ones, without departing from the scope of protection defined by the attached claims.