FFP2-type filter face masks with two layers

Abstract

The object of the present invention is the preparation of an FFP2NR-type mask made up solely of two layers of meltblown nonwoven fabric with high filtering power bonded through thermal fusion with a layer of spunbond fabric.

Description

[0001] The subject of the present invention is the preparation of an FFP2NR-type mask made up solely of two layers of meltblown nonwoven fabric with high filtering power bonded through thermal fusion to a layer of spunbond fabric.STATE OF THE ART

[0002] FFP2-type face masks are able to filter up to 94% of particles suspended in the air equal to 0.6 µm in size. They provide effective protection against smoke, dust, aerosols, bacteria and viruses. Face masks with filtering capacity are obtained by using generally two different types of nonwoven fabric superimposed according to combinations that vary according to the type of mask. Spunbond nonwoven fabric has the main function of mechanical support and of comfort in contact with the skin of those who wear them, while meltblown nonwoven fabric, with a denser weave, guarantees filtering capacity and breathability. The main function, that is the filtering capacity, is therefore guaranteed above all by the meltblown layer.

[0003] Meltblown nonwoven fabric is prepared through extrusion of the melted polymer, typically polypropylene, by means of a particular "blown spinning" technology. In this way long and very thin fibres are produced which are stretched and cooled by blowing warm air while the fibres are projected onto a collection support (a cylinder or another appropriate surface). In this way a strip of finely entangled microfibres is created which is collected into rolls and subsequently converted into finished products. The fibres produced in this way are extremely fine.

[0004] According to the spunbond technique, the fibres of polypropylene (PP) are spun and then dispersed directly onto a baffle net by means of air jets. The spunbond technology allows high speeds and economical production costs. The PP microfibres are bonded by resins or thermally. There are different variants of the spunbond spinning technology. Polypropylene (PP) spunbonds are produced with even higher speed and at decidedly lower temperatures with respect to nonwoven fabrics of different composition, exploiting the lower melting point.

[0005] The spunbond technology allows nonwoven fabrics to be obtained that are characterised by microfibres of larger size with respect to the meltblown technology. On the other hand the spunbond nonwoven fabrics are decidedly more robust. The larger microfibres of spunbond spinning do not confer high filtering capacity which is instead guaranteed by the meltdown nonwoven fabric.

[0006] For this reason, the meltblown (M) is already bonded in production (or subsequently) with yarn generated with the spunbond technology (S). Thus so-called "SM" or "SMS" (spun-melt-spun) tapes are obtained. These "composite" nonwoven fabrics combine the properties of the two spinning technologies. They are in fact adequately robust and have the microfiltering advantages of very fine fibres. The masks are typically constituted by the superimposing of at least three layers of nonwoven fabric with different functions and features: normally an external layer of hydrophobic spunbond (S) nonwoven fabric, with good mechanical strength, a filtering layer of meltblown (M) nonwoven fabric, made up of smaller microfibres (1-3 m), and an internal layer again of hydrophobic and biocompatible spunbond (S) nonwoven fabric intended to come into contact with the skin.

[0007] Only nonwoven fabric with at least three layers (S-M-S) is able to date to meet the requirements of efficacy of the filtration capacity (PFE) and of breathability of the mask. The devices currently available are mostly made up of a minimum of 4 to a maximum of 6 layers of nonwoven fabric.

[0008] Japanese patent application 2005 124 777 (A1) provides a multi-layer face mask including a photocatalytic layer.DESCRIPTION OF THE INVENTION

[0009] The object of the present invention is the manufacture of an ergonomic, lightweight and breathable face mask able to ensure the filtering performances provided by the EN149 standard in force.

[0010] It has now surprisingly been found that this object can be achieved as set forth in the appended claims, using only two layers, one of meltblown polypropylene and one of spunbond polypropylene appropriately bonded.

[0011] The solution proposed by the invention is advantageous and overcomes the disadvantages of the prior art connected to multilayer configurations rather than simply with two layers, not only maintaining the filtration efficacy of traditional masks but also improving it.

[0012] FFP2-type face masks, are made up of a material with two layers obtained by thermal fusion of a layer of meltblown polypropylene with grammage of 30-50g / m 2< on a layer of spunbond polypropylene nonwoven fabric with grammage of 30-50g / m 2< .

[0013] The density of the material with two layers which makes up the mask of the invention is comprised between 0.90 and 0.96 kg / dm 3< .

[0014] The thermal fusion of the layer of meltblown polypropylene on the layer of spunbond polypropylene nonwoven fabric takes place at a temperature of 150-200°C, preferably 160°C approximately.

[0015] The spunbond polypropylene is a nonwoven fabric made up of continuous filaments in 100% polypropylene arranged randomly and welded thermally via a calendering process.

[0016] The meltblown is made up of polypropylene microfibres with diameter 2 nm.

[0017] The meltblown is characterised by the extrusion of the melted polymer by means of a particular technology of blown spinning. By means of the stretching action of a flow of compressed and overheated air, the mass of melted polymer is transformed into long and very thin fibres which are projected onto a collection support traversed by a cooling air flow. In this way a veil of finely entangled microfibres is created which is collected in reels and subsequently converted into finished products.

[0018] Table 1 here below are the technical features - mechanical-dielectric-thermal - of the polypropylene used for the production of the masks. Table 1PROPERTIES UNIT OF MEASUREMENT METHOD PP MECHANICAL SPECIFIC WEIGHT g / cm 3< ISO 1183 0.91 Yield stress MPA DIN EN ISO 527 32 ELONGATION AT BREAK % DIN EN ISO 527 70 ELONGATION AT YIELD % DIN EN ISO 527 32 MODULUS OF ELASTICITY MPA DIN EN ISO 527 1400 SHORE D HARDNESS - ISO 868 70 SHOCK RESISTANCE KJ / m 2< DIN EN ISO 179 NR RESILIENCE KJ / m 2< DIN EN ISO 179 7 DYNAMIC FRICTION COEFFICIENT - ISO / DTR7147 - THERMAL MELTING POINT °C - 164 OPERATING TEMPERATURE °C - 0 / +100 COEFFICIENT OF LINEAR EXPANSION K-1 DIN 53752 1.64X10-4 THERMAL CONDUCTIVITY W / m•K DIN 52612 0.22 COMBUSTION BEHAVIOUR - UL94 HB DIELECTRIC DIELECTRIC RIGIDITY KV / mm IEC243-1 52 SURFACE RESISTANCE OHM DINIEC167 1014

[0019] The assembly by spray thermal fusion of the spunbond on the meltblown improves the properties of filtration of the materials for half masks evaluated according to the standard EN149: the PP material produced by the combining of the two fabrics has the features indicated in the Table 2 below, which correspond to the specifications of the FFP2 class. Table 2Pressure drop or breathability (ΔP) 2< PenetrationΔP after P.O SatPenetration after P.O.SatΔP after storagePenetration after storage (mm)Pa / cm 2< %Pa / cm 2< %Pa / cm 2< %50+ / -10>9555+ / -10>9450+ / -10>94

[0020] The data given show that the material with two layers obtained according to the invention improves the performances both of breathability and of filtration. The tests which the face masks of the invention underwent indicated improved respiratory performances, bringing the values from 2.9 / 2.8 to 2.4 / 2.3.

[0021] The material with two layers has a thickness of approximately 0.5 mm and is therefore thinner and therefore lighter than those conventionally used for FFP2 masks. The two-layer material is cut into the shapes and into the sizes required to form the final product.

[0022] Elastics or ties are applied to the mask, connected using glues already tested and approved for food or biomedical use.

[0023] Thanks to the use of a lightweight and thin material it is possible to make masks that also meet in full criteria of aesthetics (applying for example designs with continuous elements imprinted at the sides which highlight the simplicity of the design thereof) and ergonomics (adaptability to the anatomy of the face, lack of friction, easy and intuitive use).

Claims

1. A method for the preparation of FFP2-type face masks consisting of a two-layer material which comprises thermally fusing a layer of meltblown polypropylene with grammage of 30-50g / m2 onto a layer of spunbond nonwoven polypropylene fabric with grammage of 30-50g / m2, characterised in that said two-layer material having density of 0.90-0.96 kg / dm3, and in that thermal fusion is carried out by spraying the meltblown polypropylene layer onto the spunbond nonwoven polypropylene layer at a temperature of 150-200°C.