IT202100018959A1 - Antimicrobial fabric and its uses - Google Patents

Description

Description of the industrial invention entitled: ?Antimicrobial fabric and its uses?

The present invention relates generally to an antimicrobial fabric. Pi? in particular, the invention refers to a fabric with the ability to to prevent the proliferation of microbes and reduce the contaminating microbial load, and to a process for the production of said antimicrobial fabric.

The proliferation of microorganisms such as bacteria, fungi and viruses on textile products, in particular on clothing and home textiles, such as towels, sheets, upholstered furniture and curtains, favored by adequate temperature and humidity conditions, ? frequently the cause of the onset of bad odors and stains. Prolonged contact of contaminated tissue with skin can It can also lead to the onset of allergies and various pathologies, even of a certain seriousness, especially in immunosuppressed people.

Typically, the sanitization and disinfection procedures of textile items and workwear are of primary importance in the medical sector. For example, visits to patients, frequenting wards, corridors, consulting rooms and common areas involve a considerable risk of contamination of doctors' gowns which can therefore become dangerous vehicles for pathogens.

The relevance of disinfection and sanitization of clothes and fabrics? even more felt in the latter period when the ongoing severe pandemic caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed major health challenges of many countries, in order to reduce dangerous infections and ensure the health of health workers.

In this context, therefore, arises the need to make available a fabric with the ability? to prevent and/or inhibit the proliferation of microorganisms on its surface and/or inside it, thus reducing the onset of bad odors as well as? the risk of contamination by dangerous pathogens.

Is there a particular need? to make available a fabric which is endowed with an effective antibacterial and antiviral action at the same time, without harmful effects on the human or animal body, in order to guarantee adequate protection against the transmission of dangerous microbiological agents.

These and other objects are achieved thanks to an antimicrobial fabric, a process for its production and the uses of said fabric as defined in the annexed independent claims.

Further characteristics of the invention are identified in the dependent claims, which form an integral part of the description.

In the continuation ? provided a detailed description of the antimicrobial fabric according to the invention, as well as of the process for its production, which constitutes a second aspect of the present invention. A third aspect of the present invention relates to the applications of use of the antimicrobial fabric of the invention.

The expression ?antimicrobial?, as used herein, means the property? of a substance or material to eliminate an infecting microorganism and/or prevent its action, for example by inhibiting a metabolic process or a synthesis pathway present at the level of the microorganism. In the context of the expression ?antimicrobial? are understood as included the? activity? antibacterial, which acts mainly against bacteria, the activity? antifungal, directed against the pathogens responsible for mycoses, and the activity? antiviral or virucidal, capable of destroying or inactivating viruses.

With the expression ?biocidal? means any substance or mixture, used with the intent to destroy, eliminate, render harmless, prevent the action or otherwise exert a controlling effect on any harmful organism, by any means other than mere physical or mechanical action.

In the context of the present description the expressions ?antimicrobial? and ?biocide? are used interchangeably with each other.

As previously indicated, the present invention relates to a fabric consisting of a weave of fibers impregnated with one or more fibers. quaternary ammonium salts, characterized by the fact that one or more? quaternary ammonium salts comprise at least one linear or branched alkyl chain, saturated or unsaturated, containing at least 8 carbon atoms.

The term "quaternary ammonium salt" as used herein refers to a class of organic compounds in which a positively charged nitrogen atom shares its valence electrons with carbon atoms which are part of organic groups. According to the invention, the? One or more? quaternary ammonium salts with which the fibers in the antimicrobial fabric are impregnated comprise at least one linear or branched alkyl chain, saturated or unsaturated, containing at least 8 carbon atoms.

Preferably, the? one or more? quaternary ammonium salts in the fabric according to the invention are alkyl-benzyl-dimethylammonium halides, more? preferably alkyl-benzyldimethylammonium chlorides, whose alkyl chain, linear or branched, saturated or unsaturated, contains a number of carbon atoms comprised between 8 and 20, preferably between 8 and 18, even more? preferably between 8 and 16 (CAS number 63449-41-2).

Within the scope of the present description, a mixture comprising alkyl-benzyldimethylammonium chlorides as defined above with an alkyl chain having a number of carbon atoms between 8 and 18 ? referred to as ?benzalkonium chloride?.

According to the invention, ? particularly preferred is the use of a mixture comprising alkyl-benzyl-dimethylammonium chlorides with alkyl, linear or branched, saturated or unsaturated chain, having a number of carbon atoms ranging from 12 to 16 (CAS number 68424-85-1).

The quaternary ammonium salts as defined above, in particular benzalkonium chloride, are known to exert a powerful biocidal action, even at low concentrations. As illustrated more? in detail in the experimental part that follows, the particular characteristics of the fabric according to the invention give said product a significant biocidal efficacy which is expressed in the ability? to obtain a reduction of more than 99% of the contaminating bacterial or viral load, without causing harmful effects on the skin or mucous membranes at the same time.

In a preferred embodiment of the fabric of the invention, the one or more? quaternary ammonium salts are present in a quantity? total between 1.6 and 2.6 grams/m < 2 > of fabric, for example in a quantity? total of 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5 or 2.6 grams/m<2 > of fabric.

Preferably, the quantity? total of? one or more? quaternary ammonium salts present in the fabric according to the invention ? of 2.0 grams/m<2 >of fabric.

Advantageously, the properties anti-microbial properties of the fabric according to the invention, in particular the activities antibacterial and antiviral, remain active over time and, thanks to the continuous inhibition of the potential growth of harmful microbes, allow a constant self-sanitization process. From there? does it result in a reduced need? the washing frequency of the product incorporating the fabric, with the obvious advantage of a lower environmental impact and less wear.

In the fabric of the invention, the interweaving of fibers can include natural fibers, man-made fibers, synthetic fibers or mixed fibers.

Natural fibers are taken from materials that exist in nature. Among the natural fibers suitable for use in the antimicrobial fabric according to the invention, there are mentioned, by way of non-limiting example, cotton, linen, hemp, jute, wool, silk, cashmere, camel, angora and any combination or weaving thereof.

Artificial fibers are mainly obtained by treating the cellulose of different plants. Examples of man-made fibers according to the invention include viscose (rayon), acetate, modal, lyocell, and any combination thereof.

With reference to synthetic fibers, mention is made, for example, but not exclusively, of polyester, polyamide fiber (nylon), polyurethane fiber (elastane), and any combination thereof.

Alternatively, the fabric object of the invention can be made up of mixed fibers, in which case the mixed fibers preferably comprise one or more? between polyester and nylon.

The choice of fibers suitable for use in the fabric of the invention is largely within the ability of the branch technician.

A further object of the present invention is a process for the production of an antimicrobial fabric. This process comprises the step of immersing a fabric in an aqueous mixture comprising one or more quaternary ammonium salts comprising at least one saturated or unsaturated linear or branched alkyl chain containing at least 8 carbon atoms.

In the aqueous mixture used in the process according to the invention, one or more quaternary ammonium salts are as previously defined in relation to antimicrobial fabric.

Preferably, the? one or more? quaternary ammonium salts in the aqueous mixture are alkyl-benzyl-dimethylammonium chlorides with an alkyl chain, linear or branched, saturated or unsaturated, containing from 8 to 18 carbon atoms, plus? preferably between 12 and 16 (CAS number 68424-85-1).

In a preferred embodiment the one or more? quaternary ammonium salts are present in the aqueous mixture in an amount? total between? 1% and 2.5%, preferably between? 1.5% and 2.3%, for example in a quantity? total of 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3% by weight on total weight of the mixture.

In a more preferred embodiment, the one or more? quaternary ammonium salts are present in the aqueous mixture in an amount? total of 2.0% by weight on the total weight of the mixture.

In the process of the invention, the aqueous mixture can otherwise? comprising at least one glycol ether. Typically, glycol ethers have an activity? wetting agent which favors the absorption of the aqueous mixture in the fibers of the fabric.

Glycol ethers suitable for use in the aqueous mixture of the process of the invention are, for example, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-butoxyethoxyethanol, 2-phenoxyethanol, and any combination thereof.

The at least one glycol ether in the aqueous mixture of the process of the invention is preferably 2-butoxyethanol.

In a preferred embodiment, the at least one glycol ether is present in the aqueous mixture in a quantity? total between 0.1% and 1%, preferably between 0.15% and 0.9% by weight on the total weight of the mixture, for example in an amount? total of 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% wt by wt total of the mixture.

In the aqueous mixture used in the process of the invention can? otherwise? be present a pH regulator, preferably an organic acid, more? preferably citric acid and/or acetic acid.

In a preferred embodiment, the pH adjuster is present in the aqueous mixture preferably in a quantity? between 0.01% and 0.1% by weight of the total weight of the mixture, plus? preferably between 0.015% and 0.09% by weight on the total weight of the mixture, for example in an amount total of 0.015%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09% by weight on the total weight of the blend.

The pH value of the aqueous mixture according to the invention ? preferably in the range between 6.0 and 6.5.

A first preferred aqueous mixture used in the process according to the invention comprises the components: 2% by weight of one or more? alkyl-benzyl-dimethylammonium chlorides with a straight or branched alkyl chain, saturated or unsaturated, containing from 8 to 18 carbon atoms, 0.2% by weight of 2-butoxyethanol, and 0.025% by weight of citric acid on the total weight of the mixture.

A second preferred aqueous mixture used in the process according to the invention comprises the components 1.8% by weight of one or more? alkyl-benzyl-dimethylammonium chlorides with a straight or branched alkyl chain, saturated or unsaturated, containing from 12 to 16 carbon atoms, 0.25% by weight of 2-butoxyethanol, and 0.025% by weight of citric acid on the total weight of the mixture.

According to the invention, the aqueous mixture of the process of the invention can include additional active compounds or additives.

The fabric used in the process of the invention can be manufactured using different weaving techniques, for example by using circular, run-knit looms, flat or jacquard looms, using natural, artificial or synthetic fibers as previously described. The weaving techniques are known and described in the state of the art, so their choice and use fall within the capabilities of the average technician in the sector.

In the process according to the invention, the step of immersing the fabric in the aqueous mixture is preferably made by sliding the fabric inside tanks containing the aqueous mixture (bath).

In a preferred embodiment, the immersion takes place by means of the "foularding" procedure, which provides for the passage of the fabric initially through expanding and tightening cylinders and then, in width, into a tank in which the fabric is impregnated with the aqueous mixture according to the invention. At this step can? follow a squeezing of the fabric between cylinders, in order to push the mixture into the fibers and at the same time eliminate the excess.

Optionally, after the soaking step, the fabric can be subjected to drying at a temperature between 130?C and 150?C, preferably at a temperature of 140?C, in order to eliminate the excess of the aqueous mixture and heat-fix one or more? quaternary ammonium salts with activity? antimicrobial.

A third aspect of the invention relates to the uses of the antimicrobial fabric. As previously mentioned, the particular activities? The antibacterial and antiviral properties of the fabric of the invention are characterized by significant persistence over time, thus allowing the complete elimination or significant reduction of any microbial contamination by people or animals in the time intervals between successive uses of the fabric. Thanks, therefore, to the particular combination of a constant activity? antimicrobial and safety for the skin and/or mucous membranes, the fabric of the invention? particularly suitable for use in the manufacture of clothing products, furnishing textile products and/or medical textile products.

Examples of clothing products particularly suitable for being manufactured with the antimicrobial fabric according to the invention include medical and hospital clothing, for analysis laboratories, for sterile rooms, and for environments with a high risk of contamination; clothing for the food, pharmaceutical and chemical industries; army clothing; sportswear, and uniforms for cooks and waiters.

Further suitable applications of the fabric of the invention concern, for example, the manufacture of textile products for furnishings (curtains, bed linen, home furnishing fabrics, chair and seating coverings), coverings of office furniture components or fabrics for vehicle interiors, including but not limited to, fabrics for seats and linings, door panels, armrests and child seats, as well as as any protective textile product capable of covering all or part of a person, tool or piece of equipment, clothing accessory or shoe.

The following examples are provided for illustrative and non-limiting purposes of the scope of the invention as defined in the annexed claims.

EXAMPLES

1. Manufacturing process and impregnation of the antimicrobial fabric

For the manufacture of the fabric of the invention different weaving methods were used as illustrated below.

PLAIN/JACQUARD WEAVING

Traditional weaving consisting of a weaving of more? threads perpendicular to each other: the warp threads are longitudinal to the fabric, while the weft threads are transversal.

The processing takes place with electric looms that are divided into two types: flat looms that allow the creation of fabrics without a design or with a regular design, or jacquard looms that allow you to have individual control over each warp thread, thus passing the weft above or below each thread at will allowing the creation of even complex designs.

CIRCULAR WEAVING

The circular weaving, called ?knit?, starts from the loading of the individual machine-dyed cones. The yarns are woven into consecutive loops which form the knit.

Unlike flat/jacquard weaving, the fabric for its structure is? much more elastic and lends itself better to subsequent saddleing, but the structure? inevitably less resistant than plain/jacquard technology.

WEAR-KNITTABLE WEAVING

Weaving technology that involves the use of special thread spools purchased separately with which it is ? possible to create microfibers and velvets. Usually the fabric created with these looms? white and will subsequently dyed by external suppliers to then re-enter the production flow in the finishing.

FINISHING

After manufacturing, the fabric ? been subjected to finishing, a process that is divided into three phases that can be linked together: fabric washing, foulard bath, heat setting.

The oils used in weaving and present in the yarn were removed through the washing phase; the mixture used? been soap and water. Then the fabric? entered into a tank containing the mixture of the process of the invention. The soaked tissue? been subsequently squeezed with a mechanical system and, after squeezing, ? entered in an oven at a temperature of 140?C for the heat setting phase, with permanence of about 3 minutes.

2. Evaluation of the activity? tissue antiviral of the invention

The activity fabric antiviral of the invention ? been evaluated using a quantitative analysis method according to the ISO 18184 standard ?Determination of?Activity? Antiviral of Textiles?.

The present inventors initially conducted the evaluation assays using bacteriophages as the biological agent. In short, a solution containing a known viral titer (inoculum) ? been placed in contact with the surfaces of a test sample of the fabric to be analyzed and subsequently ? the residual viral load after predetermined contact times (T) was measured.

The antiviral performance of the analyzed samples ? was determined by comparing the residual infectious viral load on the tissue samples of the invention after the incubation period (18 hours) with respect to the initial load, resulting from the first immediate recovery after inoculation on an untreated tissue sample. Results for treated tissue samples and untreated control samples were also compared for each analysis time point (T). In addition, the percentages of reduction of the viral load with respect to the initial load at time T0 resulting from the inoculation on the untreated sample were reported.

In particular, for the aforementioned essays ? Was the MS2 bacteriophage used (DSM 13767. ATCC 15597-B1), at a concentration in the inoculum equal to 1.4x10<7>unit? plaque forming units (?plaque forming units?, pfu). The contact time (incubation) ? lasted up to 18 hours since the bacteriophage viruses, in the presence of bacterial cells that are commonly present on surfaces, continue to replicate without an initial significant decrease.

Table 1 below shows the antiviral performance of the antimicrobial tissue of the invention indicated as Log10 and Reduction% compared to the untreated control sample.

Table 1

The absolute pfu values in the table correspond to the common logarithm of the number of units? forming plaque as the average of 3 samples analysed.

The results of the analyzes illustrated above show that the fabric of the invention is surprisingly capable of achieving a reduction of about 99.9% of the contaminating viral load in a given time.

For the evaluation of? activity? tissue antiviral of the invention, the present inventors conducted further analyzes using specific viruses acting on humans, in particular SARS-CoV-2. This virus does not persist for long outside a host and, therefore, unlike bacteriophages, the characteristics of the test - temperature and humidity controlled - prevent this biological agent from surviving for long times on a polyester fabric which, being by its nature an environment that is not favorable to viral survival, therefore marks a rapid deterioration.

In light of this, in order to obtain significant results, the analysis times during the tests were reduced to 30 minutes and one, two or four hours. As reported in tables 2 and 3 below, the results achieved by testing SARS-CoV-2 and using reduced times have demonstrated also in this case a high antiviral efficacy of the antimicrobial fabric of the invention:

Table 2

Table 3

To attribute antiviral efficacy to the Mv value with respect to time 0 (T0) of the untreated sample? the formula was applied:

Mv = log(Va) - log(Vc).

The results obtained were then reported in the evaluation table 4:

Table 4

The percentage of effectiveness ? was calculated using the formula:

For the samples treated with antivirus treatment, the antiviral efficacy (%) at T30? ? was:

In the light of the previously described results, the antimicrobial fabric of the invention is revealed endowed with a? activity? extremely high antiviral also against SARS-CoV-2.

3. Evaluation of the activity? antibacterial of the fabric of the invention

In order to evaluate the ability antibacterial properties of the antimicrobial fabric of the invention ? was a quantitative analysis method carried out according to the UNI EN ISO 20743 standard ?Determination of?Activity? Antibacterial of Textile Products?.

The tests were performed on tissue samples of the invention and on control samples of untreated tissue, which were placed in contact with agar medium in which the bacterial solution had been inoculated.

The antimicrobial tissue samples were examined after two different times of contact (incubation), at the end of which they were analyzed to determine the activity value? antibacterial, what? was then compared with the value of bacterial growth found on the control samples. Pi? specifically, for the aforementioned tests, cultures of the bacterium Staphylococcus aureus (ATCC 6538) and of the bacterium Klebsiella pneumoniae (ATCC 4532) were used, at inoculum concentrations equal, respectively, to 7.55x10<5>unit? colony forming (CFU) and 2.63x10<5 >CFU. The incubation of the samples ? was conducted for 3 and 6 hours.

Table 5 below shows the antibacterial performance of the antimicrobial fabric of the invention compared to the untreated control sample.

Table 5

The results of the previously described analyzes show that the fabric of the invention is surprisingly capable of achieving in a very rapid time, already? at T0, a reduction of approximately 99.9% of the contaminant bacterial load.

4. Evaluation of the risk of damage to the skin and/or mucous membrane of the fabric of the invention

As previously illustrated, the antimicrobial fabric object of the invention ? impregnated with one or more? quaternary ammonium salts, preferably benzalkonium chloride (or benzalkonium chloride) which ? just a mixture of ammonium salts.

As ? known in the art, benzalkonium chloride at room temperature? a light yellow solid deliquescent (dissolves in water which it absorbs from air), very soluble in water with a strong aromatic odour.

According to the Assessment Report available on the European Chemicals Agency website? (ECHA) (https://echa.europa.eu), alkyl(C12-C16)-benzyldimethylammonium chloride molecules are corrosive and can cause skin irritation at certain concentrations.

In general, the corrosion effects of the aforementioned molecules are not considered relevant if the concentrations remain below < 1%.

The aqueous mixture used in the process according to the invention contains a maximum concentration of alkyl(C12-C16)-benzyldimethylammonium chloride active principle equal to 2.5%. Considering the scenario pi? burdensome, thus it results:

Table 6

From the data reported in Table 6 above, it can therefore be deduced that the active principle of the aqueous mixture of the process of the invention remains in the treated fabric with a percentage < 1%. Below this percentage, the Authority? expert, during the evaluation of the active ingredient for PTs 3-4-8 (PT3: veterinary hygiene; PT4: food and feed; PT8: wood preservatives) did not detect local effects and, in the absence of such effects, did not no systemic effects were detected.

In the light of the foregoing, the antimicrobial fabric of the invention does not qualify as dangerous, does not require indications of danger or precautions and is not? subject to the safety data sheet obligation.

Claims (10)

1. Antimicrobial fabric consisting of a weave of fibers impregnated with one or more? quaternary ammonium salts, characterized by the fact that one or more? quaternary ammonium salts comprise at least one linear or branched alkyl chain, saturated or unsaturated, containing at least 8 carbon atoms. 2. Antimicrobial fabric according to claim 1, wherein one or more Quaternary ammonium salts are alkyl-benzyl-dimethylammonium chloride with a saturated or unsaturated straight or branched alkyl chain containing between 8 and 18 carbon atoms. 3. Antimicrobial fabric according to claim 1 or 2, wherein one or more? quaternary ammonium salts are present in a quantity? total between 1.6 and 2.6 grams/m<2> of said fabric. 4. Antimicrobial fabric according to any one of claims 1 to 3, wherein the fibers in the weave are selected from natural fibers, artificial fibers, synthetic fibers, and any combination thereof. 5. A process for producing an antimicrobial fabric, comprising the step of immersing a fabric in an aqueous mixture comprising one or more? quaternary ammonium salts comprising at least one saturated or unsaturated linear or branched alkyl chain containing at least 8 carbon atoms. 6. Process according to claim 5, wherein one or more? quaternary ammonium salts in the aqueous mixture are alkyl-benzyldimethylammonium chloride with a saturated or unsaturated straight or branched alkyl chain containing from 8 to 18 carbon atoms, and one or more? quaternary ammonium salts are preferably present in the aqueous mixture in an amount total between 1% and 2.5% by weight on the total weight of the mixture. 7. Process according to claim 5 or 6, wherein the aqueous mixture also comprises at least one glycol ether and/or at least one pH adjusting agent. 8. Process according to any one of claims 5 to 7, wherein the at least one glycol ether in the aqueous mixture is? selected from the group consisting of 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-butoxyethoxyethanol, 2-phenoxyethanol, and any combination thereof, and the at least one glycol ether ? preferably present in the aqueous mixture in a quantity? total between 0.1% and 1% by weight on the total weight of the mixture. 9. Process according to any one of claims 5 to 8, wherein the at least one pH adjusting agent in the aqueous mixture is selected from citric acid and acetic acid, and the at least one pH regulating agent ? preferably present in the aqueous mixture in a quantity? total between 0.01% and 0.1% by weight on the total weight of the mixture. 10. Use of an antimicrobial fabric according to any one of claims 1 to 4, for the manufacture of garments, furnishing textile products and/or medical textile products.