Field of technology

The technical solution that we present here concerns water-soluble filter material and protective equipment containing it.

Current state of technology

Nowadays, many filter materials have been developed that prevent the passage of pathogens, especially viruses and bacteria. Many of these filter materials contain nanofibrous layers and layers of non-woven fabric.

Due to frequent use of filter materials, especially masks, respirators and similar protective equipment, a large amount of waste is generated that needs to be disposed of. There is also environmental pollution with protective equipment that is thrown out of trash cans and containers. The present technical solution aims to solve the above-mentioned problem.

Principles of the technical solution

The subject of the present technical solution is a filter material containing at least three layers, wherein there are at least three layers including at least two layers of non-woven fabric and at least one nanofibrous layer inserted between the specified layers of non-woven fabric, the material of all layers being polyvinylalcohol (PVA) which is the point of the matter.

The filter material contains two layers of non-woven fabric and one nanofibrous layer inserted between the specified layers of non-woven fabric in a preferred embodiment, while polyvinylalcohol (PVA) is the material of all layers.

Advantageously, at least one virucidal and/or bactericidal agent is absorbed or incorporated in at least one layer of the filter material. The virucidal and/or bactericidal agent is advantageously selected from a group of plant extracts, essential oils and their mixtures; more preferably from a group consisting of licorice extract, aloe extract, chamomile extract, hemp extract, mulberry extract, eucalyptus extract, Cretan cistus extract, cork tree extract, peppermint extract, thyme extract, eucalyptus oil, lavender oil, Australian tea plant oil, peppermint oil, ginger oil, thyme oil, laurel oil and mixtures thereof.

More preferably, the virucidal and/or bactericidal agent is selected from the group of licorice extract and eucalyptus extract.

Extracts are mainly aqueous or alcoholic (especially ethanol) extracts.

Advantageously, the virucidal and/or bactericidal agent is absorbed in the nanofibrous layer. Nanofibres generally mean fibres with a diameter between 1 and 900 nanometres. The use of nanofibres with a diameter ranging from 100 to 350 nanometres is particularly advantageous in this technical solution. The diameters of the nanofibres are measured by scanning electron microscopy (SEM). Such nanofibres can be prepared by methods such as electrospinning, pulling, jet spinning, and other methods known to those skilled in this discipline.

The layers of filter material can be connected, for example, by thermal welding, ultrasonic welding, sewn joints, glued joints, etc.

Protective equipment for personal protection containing filter material according to the technical solution and fastening means is another matter of the technical solution, the material being polyvinylalcohol. Fastening means include, in particular, laces, rubber bands, grips and/or clamps.

Protective equipment for personal protection mainly includes masks and respirators.

This technical solution therefore provides filter material and protective equipment, the material of which is polyvinylalcohol. Such products are soluble in water, the solubility increases with temperature. At temperatures above 40 °C, polyvinylalcohol products dissolve in water, while at temperatures between 20 and 30 °C, the solubility of polyvinylalcohol in the form of non-woven fabric and nanofibres is low, therefore when in contact with air containing a certain amount of moisture, at these temperatures there will be no decrease in functionality of the filter material for several hours. At temperatures above 40 °C and in contact with water, the filter material and the protective agents dissolve within a few minutes (for example, in a washing machine or when poured with warm water).

Polyvinylalcohol is also well biodegradable. Discarded filter materials therefore quickly dissolve and degrade in the environment and they do not produce toxic substances.

In case of presence of a virucidal and/or bactericidal agent, these agents are natural and therefore both the dissolution of the filter material and of the protective equipment in water and their decomposition in the environment will not lead to the formation or release of toxic substances.

Examples of realization of the invention

Example 1: Preparation of filter material

A nanofibrous layer was prepared by electrospinning from a 12% (Wt/Wt) aqueous solution of polyvinylalcohol (PVA) on a SPINLAB device. The SEM image of the nanofibrous layer is shown in Fig. 1, the diameter of the nanofibres was in the range of 110 to 300 nm. The nanofibrous layer was then impregnated with licorice extract. Alternatively, the virucidal and/or bactericidal agent can be added into the polyvinylalcohol solution for a spinning procedure in a weight ratio of 95:5 to 50:50 PVA:agent.

Non-woven fabric layers made of polyvinylalcohol were purchased from a commercial supplier.

They were stacked on top of each other: a non-woven fabric layer, a nanofibrous layer, and a nonwoven fabric layer.

The layers were ultrasonically welded around the perimeter and at points in the area as well. This is how the filter material was prepared and it was subsequently tested.

The filter material can also be prepared in the form of a mask or a respirator and equipped with clamps and grips or laces made of polyvinylalcohol.

Example 2: Testing the filter material

The samlpes of the filter material were tested in a laboratory of the Technical University in Liberec. The samples were placed in a filter holder and sealed at the edges. The samples were placed in a box with an opening of 100 cm ² . Pressure drop (breathing resistance) was measured at flow rates of 30 l/min, 95 l/min and 160 l/min.

In another test, oil particles (paraffin oil) having a size in the range of 0.12 to 3 micrometers were dispersed in the air and the penetration through the tested filter at a flow rate of 95 l/min was monitored. The particles that passed through the filter were diluted and analyzed using an optical computer. The concentration of particles of a given size before and after the filter was determined, and for each particle size the filtration efficiency (particle capture efficiency) was calculated according to the formula:

E = (1-(C after the filter / C before the filter)). 100(%).

For the classification of respirators according to the standard EN 149:2001, the particle capture efficiency of 0.6 micrometres was used.

To estimate the classification of masks according to the standard EN 14683:2019, the particle capture efficiency with a size of 3 micrometres was used.

The filter efficiency measurement error is 0.2% of the measurement range, the pressure drop measurement error is 6% of the range for the 0 to 100 Pa range and 4% of the range for the 100 to 500 Pa range.

The MFP 1000 HEPA testing device manufactured by Palas GmbH was used.

The test results are shown in the table: