ANTIMICROBIAL SYNTHETIC TEXTILE AND A METHOD FOR MANUFACTURING THEREOF

[0001] The present disclosure relates to antimicrobial synthetic textiles and methods for manufacturing antimicrobial synthetic textiles. The present disclosure further concerns use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile.

[0002] Antimicrobial textiles offer several benefits in professional, health care and home environments such as reduction of microbe growth and odor control. Home textiles have always been a major part of the global textile trade. Also, the exponential spread of COVID-19 across the globe along with a rising requirement for smart medical textiles in healthcare facilities has boosted the antimicrobial textile market. Synthetic polyester fabrics dominate the consumption of antimicrobial fabrics with almost half of the global market share and are likely to showcase a compound annual growth rate (CAGR) of over 9.2% through 2027.

[0003] Antimicrobials used in textiles range from synthetic organic compounds such as triclosan, quaternary ammonium compounds (QACs), polybiguanides, brominated phenols and N-halamines to metals such as silver, copper and zinc. Many of these commonly used antimicrobial agents have some undesired properties. For example, silver ions and QACs are poorly biodegradable, and when released into the environment they are very toxic to aquatic organisms. Also, some of the commonly used antimicrobial chemicals potentially contribute to the emergence of antimicrobial resistance (AMR), i.e. antibiotic-resistant bacteria and other types of multidrug-resistant microbes. It is known that silver, copper and zinc are released in high amounts from antimicrobial coatings to the aquatic ecosystems. Studies have shown that of the antimicrobial substances triclosan, triclocarban and silver in textiles, on average 60% of the antibacterial substance was washed out after 10 washes and even up to 100% of the substance was washed out over time.

[0004] An antimicrobial treatment performed on a textile needs to satisfy different requirements besides being efficient against microorganisms. These include being suitable for textile processing, presenting durability to laundering, dry cleaning and hot pressing, presenting a favorable safety and environmental profile, and not harming textile quality or appearance. There is a longstanding need for a synthetic textile treatment composition which permits a durable and safe antimicrobial finish and can be applied simply and inexpensively.

[0005] An object of the present disclosure is to provide a method for manufacturing an antimicrobial synthetic textile, an antimicrobial synthetic textile obtainable by the method, and an antimicrobial synthetic textile to alleviate the above disadvantages. Also, use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile and a product comprising the antimicrobial synthetic textile are provided.

[0006] One aspect of the invention is a method for manufacturing an antimicrobial synthetic textile, comprising the steps of:

• • [0007] a) providing a treatment solution comprising a polycarboxylic acid and a catalyst;
  • [0008] b) applying the treatment solution on a synthetic textile to provide a polycarboxylic acid treated synthetic textile; and
  • [0009] c) curing the polycarboxylic acid treated synthetic textile.

[0010] A further aspect of the invention is an antimicrobial synthetic textile obtainable by the method.

[0011] Another aspect of the invention is an antimicrobial synthetic textile. Said synthetic textile comprises an antimicrobial finish which comprises a polycarboxylic acid cured in the presence of a catalyst.

[0012] Yet another aspect is a product comprising the antimicrobial synthetic textile.

[0013] A yet further aspect is use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile.

[0014] Aspects of the invention are characterized by what is stated in the independent claims. The preferred embodiments of the invention are disclosed in the dependent claims.

[0015] As used herein, the term “polycarboxylic acid” refers to organic compounds having multiple carboxylic acid functional groups. In other words, a polycarboxylic acid is an acid that has more than one carboxylic acid group.

[0016] There are plenty of free hydroxyl (—OH) groups in cellulose and cellulosic fibers such as cotton. When polycarboxylic acids are applied to produce a finish to textiles comprising cellulosic fibers, a stable covalent bond is formed via esterification of hydroxide groups and carboxylic groups. On such textiles, an antimicrobial finishing comprising esterified polycarboxylic acids is therefore automatically relatively durable.

[0017] In textile manufacturing, finishing refers to processes that convert the textile such as fiber, yarn, fabric or woven or knitted cloth into a more usable material to improve the look, performance, or “hand” (feel) of the finished textile or for example an item of clothing made from the textile. An antimicrobial finish causes the textile to inhibit growth of microbes. Infestation of textiles by microbes can cause pathogenic infection and development of odor where the textile is worn or otherwise present next to the skin. In addition, stains and loss of fiber quality of textile substrates can also take place. With an aim to protect the wearer and the textile substrate itself, an anti-microbial finish may be applied to textile materials.

[0018] Esterification is a conventionally used method in green wood modification technology.

[0019] Esterification of hydroxyl groups of cellulose with a polycarboxylic acid such as citric acid (CA) is an inexpensive and environmentally friendly cellulose modification method. Previously, polycarboxylic acids have been used in different applications on cotton fabric. These conventional methods include impregnating cotton fabric with CA and sodium hypophosphite (SHP) solution and thermally treating the fabric to bring about esterification where CA forms ester bonds with cellulose hydroxyls trough the formation of anhydrides. (Vukušic et al. Croat Med J 2011, 52: 68-75).

[0020] Since synthetic textiles lack free OH-groups on the surface compared to the naturally derived textile cotton, these synthetic materials cannot be esterified with polycarboxylic acids. Thus, it is challenging to produce an antimicrobial synthetic textile having a durable polycarboxylic acid finish.

[0021] The present invention relates to a method for manufacturing an antimicrobial synthetic textile, an antimicrobial synthetic textile obtainable by to the method and an antimicrobial synthetic textile comprising an antimicrobial finish. The present invention further relates to use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile and products comprising the antimicrobial synthetic textile.

[0022] As used herein, the term “textile” refers to various fiber-based materials, including, but not limited to, fibers, yarns, filaments, threads and different fabric types such as woven fabric, knit, non-woven fabric and cloth. Also, as used herein, the term “fabric” is defined as any thin, flexible material made from yarn, directly from fibers, polymeric film, foam, or any combination of these techniques. Also, as used herein, the term “knit” refers to a fabric formed by interlacing yarn or thread into a series of interconnected loops. Also, as used herein, the term “cloth” refers to a fabric that consists of a fine, flexible network of yarns.

[0023] Typically, the smallest component of a fabric is fiber. As used herein, the term “natural fiber” refers to fiber obtained from plants or animals, whereas the term “synthetic fiber” is used of fiber manufactured with chemical synthesis and covers also semi-synthetic fibers synthesized from natural polymers. Similarly, a “natural textile” is a textile based on plant or animal fiber(s), and a “synthetic textile” is a textile based on fiber(s) manufactured with chemical synthesis and covers also semi-synthetic fiber(s) synthesized from natural polymers.

[0024] In an aspect, the invention relates to a method for manufacturing an antimicrobial synthetic textile, comprising the steps of a) providing a treatment solution comprising a polycarboxylic acid and a catalyst; b) applying the treatment solution on a synthetic textile to provide a polycarboxylic acid treated synthetic textile; and c) curing the polycarboxylic acid treated synthetic textile. Optionally, curing is performed at a temperature in the range of 130° C. to 180° C.

[0025] In a further aspect, the invention relates to an antimicrobial synthetic textile obtainable by said method.

[0026] In another aspect, the invention relates to an antimicrobial synthetic textile, said synthetic textile comprising an antimicrobial finish comprising a polycarboxylic acid cured in the presence of a catalyst. Optionally, curing is performed at a temperature in the range of 130° C. to 180° C.

[0027] We have surprisingly found that polycarboxylic acids can be applied in finishing synthetic textiles, resulting in a very strong antimicrobial effect with good washability. As shown by the working examples, antimicrobial activity is demonstrated against both bacteria and fungi.

[0028] Manufacturing the durable antimicrobial finish involves use of a catalyst that, without being bound to any one theory, is believed to crosslink and/or polymerize the polycarboxylic acid molecules, producing a layer or network of crosslinked and/or polymerized polycarboxylic acid molecules on the surface of the textile.

[0029] The antimicrobial finish disclosed herein represents non-leaching technology and thus no or only a minimal amount of active substance is released to the environment during washing of the textile. Crosslinking and/or polymerization of polycarboxylic acid molecules is induced by curing the synthetic textile treated with one or more polycarboxylic acid(s) at an elevated temperature in the presence of the catalyst.

[0030] As used herein, the term “curing” refers to cross-linking and/or polymerizing polycarboxylic acid molecules on the surface of a synthetic textile by applying heat to said polycarboxylic acid. The curing reaction is enhanced by a catalyst and is believed to produce the toughening or hardening of the polycarboxylic acid by cross-linking and/or polymerization.

[0031] As used herein, the term “or” has the meaning of both “and” and “or” (i.e. “and/or”). Furthermore, the meaning of a singular noun includes that of a plural noun and thus a singular term, unless otherwise specified, may also carry the meaning of its plural form. In other words, the term “a” or “an” may mean one or more.

[0032] As used herein, the term “comprising” includes the broader meanings of “including”, “containing”, and “comprehending”, as well as the narrower expressions “consisting of” and “consisting only of”.

[0033] As shown by the working examples, antimicrobial activity by the polycarboxylic acid finishing produced according to the invention is demonstrated in both synthetic textiles made from a single type of polymer as well as polymer blends.

[0034] Synthetic textiles that can be used in all aspects of the invention including antimicrobial finishing by the method of the disclosure include, but are not limited to, textiles made of polyester; polyamide such as nylon; polyacrylonitrile such as acrylic and modacrylic; olefin; vinyon; polyethylene such as ultra-high-molecular-weight polyethylene (UHMWPE, UHMW), Dyneema and Spectra; elastane; vinylon; aramid such as Kevlar, Nomex and Twaron; polybenzimidazole (PBI); polyphenylene sulfide (PPS); polylactic acid (PLA); poly(p-phenylene-2,6-benzobisoxazole (PBO); Vectran; and glass fiber or any mixture thereof.

[0035] In other words, the synthetic textile is made of a polymer material having no free hydroxyl groups in their structure except optionally at the end(s) of the polymer chain. In yet other words, each polymer molecule may have up to one free hydroxyl group at each end or terminus of the molecule such as a hydroxyl group of a carboxylic acid group, and no free hydroxyl groups are present in the polymer molecule between the ends. With the ends or termini are meant the end groups of the polymer molecule.

[0036] In an embodiment, the synthetic textile comprises or consists of a polymer material, wherein the polymer molecule(s) in the polymer material comprise up to one free hydroxyl group at each end of the polymer molecule and no free hydroxyl group(s) between the ends, wherein the free hydroxyl group is independently selected from a hydroxyl group and a carboxylic acid group.

[0037] Polycarboxylic acids that may be used in all aspects of the invention including the method or the antimicrobial synthetic textile or the synthetic textile comprising an antimicrobial finish disclosed herein include, but are not limited to, citric acid (CA; CAS 77-92-9), isocitric acid (ICA; CAS 320-77-4), tricarballylic acid (TCA; CAS 99-14-9), 1,2,4-butanetricarboxylic acid (BTRCA; CAS 923-42-2), 1,2,3,4-butanetetracarboxylic acid (BTCA; CAS 1703-58-8), oxalic acid (CAS 144-62-7), tartaric acid (L(+)-tartaric acid CAS 87-69-4, and other isomers), succinic acid (CAS 110-15-6), malic acid (CAS 6915-15-7), malonic acid (CAS 141-82-2), glutamic acid (L-isomer CAS 56-86-0, and other isomers), aspartic acid (L-isomer CAS 56-84-8, and other isomers), glutaric acid (CAS 110-94-1), 1,3,5-pentanetricarboxylic acid (CAS 6940-58-=5), gluconic acid, mannaric acid, galactaric acid, maleic acid, and adipic acid. The polycarboxylic acids may also be in any isomer, salt or hydrate form including, but not limited to, sodium citrate, anhydrous (CAS 13742-35-0) and citric acid monohydrate (CAS 5949-29-1).

[0038] All aspects of the invention including the antimicrobial synthetic textile and the method of the invention involve a catalyst that is believed to enhance the rate of a crosslinking and/or polymerization reaction between the polycarboxylic acid molecules. In all aspects of the invention, sodium hypophosphite, anhydrous CAS 7681-53-0 (SHP; NaH₂PO₂), or SHP hydrates like CAS 123333-67-5 or monohydrate CAS 10039-56-2; or monosodium phosphate, anhydrous CAS 7558-80-7 (MSP; NaH₂PO₄), or MSP hydrates like monohydrate CAS 10049-21-5 or dihydrate CAS 10049-21-5, or any mixture thereof may be used as a catalyst.

[0039] In an embodiment, the polycarboxylic acid and the catalyst are provided dissolved in a solvent. The treatment solution cured to form the antimicrobial finish thus comprises the polycarboxylic acid, the catalyst and solvent. Suitable solvents include but are not limited to one or more solvent(s) selected from an aqueous solvent, water, alcohol, ether, ethyl acetate, ketone or DMSO. That is, any one of the listed solvents or any mixture of the listed solvents that is suitable for dissolving the polycarboxylic acid in question is also suitable for use in the antimicrobial synthetic textile and the method of the invention. Preferably, the solvent is water or an aqueous solvent such as a water-alcohol mixture.

[0040] In an embodiment, concentration of the polycarboxylic acid in the treatment solution is in the range of 1 to 20 wt-%, preferably 2 to 18 wt-%, more preferably 5 to 15 wt-%, even more preferably 6 to 14 wt-%, based on the total weight of the treatment solution. Additionally or alternatively, a polycarboxylic acid concentration of 1 wt-%, 2 wt-%, 3 wt-%, 4 wt-%, 5 wt-%, 6 wt-%, 7 wt-%, 8 wt-%, 9 wt-%, 10 wt-%, 11 wt-%, 12 wt-%, 13 wt-%, 14 wt-%, 15 wt-%, 16 wt-%, 17 wt-%, 18 wt-%, 19 wt-% or 20 wt-%, based on the total weight of the treatment solution, or a concentration range between any two of said concentrations may be used in the treatment solution.

[0041] In an embodiment, concentration of the catalyst in the treatment solution is in the range of 1 to 20 wt-%, preferably 2 to 18 wt-%, more preferably 5 to 15 wt-%, even more preferably 6 to 14 wt-%, based on the total weight of the treatment solution. Additionally or alternatively, a catalyst concentration of 1 wt-%, 2 wt-%, 3 wt-%, 4 wt-%, 5 wt-%, 6 wt-%, 7 wt-%, 8 wt-%, 9 wt-%, 10 wt-%, 11 wt-%, 12 wt-%, 13 wt-%, 14 wt-%, 15 wt-%, 16 wt-%, 17 wt-%, 18 wt-%, 19 wt-% or 20 wt-%, based on the total weight of the treatment solution, or a concentration range between any two of said concentrations may be used in the treatment solution.

[0042] Polycarboxylic acids, particularly citric acid and isocitric acid may begin to disintegrate at temperatures exceeding 175° C. Because of this, a textile treated with a polycarboxylic acid such as CA or ICA may have a strong tendency to turn yellow due to degradation of the polycarboxylic acid into for example unsaturated acids such as aconitic acid, particularly at high temperatures and/or during an extended time heat treatment. Therefore, it is also important to maintain a short curing time to avoid disintegration.

[0043] According to the results presented in Example 3, wash-durable antimicrobial activity was achieved when curing was performed at temperatures ranging from 150° C. to 180° C. However, we expect that in larger scale industrial applications heat transfer to the fabric in an industrial dryer is more efficient than in laboratory scale experiments such as those in Example 3. Thus, a lower temperature of 130° C. or 140° C. compared to curing in laboratory scale is sufficient in industrial scale.

[0044] In an embodiment, curing is performed in the method or the antimicrobial synthetic textile or the synthetic textile comprising an antimicrobial finish as disclosed herein at a temperature of 130° C. to 180° C., or 1350 to 180° C., or 140° C. to 180° C., or 145° C. to 180° C., or 1500 to 180° C., or 1500 to 175° C., or 1500 to 170° C. Additionally or alternatively, the curing temperature may be 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C., 165° C., 170° C., 175° C. or 180° C. or any temperature range between any two of the temperatures 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C., 165° C., 170° C., 175° C. or 180° C.

[0045] In another embodiment, curing is performed in the method or the antimicrobial synthetic textile or the synthetic textile comprising an antimicrobial finish as disclosed herein for a period of time ranging from 5, to 180 seconds, or 10 to 150 seconds, or 15 to 120 seconds, or 30 to 60 seconds. Additionally or alternatively, the curing time may be 5 s, 10 s, 15 s, 20 s, 25 s, 30 s, 35s, 40s, 45s, 50s, 55s, 60s, 65 s, 70s, 75s, 80s, 85s, 90s, 95 s, 100 s, 105 s, 110 s, 115 s or 120 s, or any time range between any two of the time durations 5 s, 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, 60 s, 65 s, 70 s, 75 s, 80 s, 85 s, 90 s, 95 s, 100 s, 105 s, 110 s, 115 s or 120 s.

[0046] Also, we have surprisingly discovered that a one-step treatment of curing may also be used to simultaneously dry the synthetic textile. In other words, a two-step treatment involving a separate drying step before the curing step is not required to achieve a durable antimicrobial finishing.

[0047] As used herein, the term “drying” refers to applying heat to the synthetic textile to achieve a reduced moisture content. Typically, drying is performed at a lower temperature than curing for example to avoid disintegration of polycarboxylic acid and to avoid occurrence or onset of the curing reaction. A one-step curing provides a fast and energy-efficient process as compared to a conventional two-step drying and curing.

[0048] In an embodiment, no drying step by applying heat to the polycarboxylic acid treated synthetic textile is performed before the curing step in the method or the antimicrobial synthetic textile as disclosed herein. In other words, drying is achieved in a single curing step performed at a temperature of 130° C. to 180° C., or 1350 to 180° C., or 140° C. to 180° C., or 145° C. to 180° C., or 1500 to 180° C., or 1500 to 175° C., or 1500 to 170° C. Additionally or alternatively, the temperature may be 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C., 165° C., 170° C., 175° C. or 180° C. or any temperature range between any two of the temperatures 130° C., 135° C., 140° C., 145° C., 150° C., 155° C., 160° C., 165° C., 170° C., 175° C. or 180° C.

[0049] Preferably, the single curing step is performed for a period of time ranging from 5 to 180 seconds, or 10 to 150 seconds, or 15 to 120 seconds, or 30 to 60 seconds. Additionally or alternatively, the curing time may be 5 s, 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, 60 s, 65 s, 70 s, 75 s, 80 s, 85 s, 90 s, 95 s, 100 s, 105 s, 110 s, 115 s or 120 s, or any time range between any two of the time durations 5 s, 10 s, 15 s, 20 s, 25 s, 30 s, 35 s, 40 s, 45 s, 50 s, 55 s, 60 s, 65 s, 70s, 75 s, 80s, 85s, 90s, 95 s, 100 s, 105 s, 110 s, 115 s or 120s.

[0050] As used herein, the term “wet pick-up” refers to the amount of fluid or solution by percent weight picked up by a textile during a method step. Wet pick-up is influenced by factors such as textile characteristics and solution properties. As used herein, the term “dry pick-up” refers to the amount of treatment chemicals by percent weight left on a textile after evaporating a solution or solvent liquid.

[0051] We have discovered that a combination of wet pick-up, polycarboxylic acid concentration such as citric acid concentration and catalyst concentration such as SHP concentration that results in dry pick-up of polycarboxylic acid and catalyst in the range of 0.5% to 20% produces a durable and antimicrobially effective finish. Preferably, the dry pick-up of polycarboxylic acid and catalyst may be in the range of 2% to 18% or 3% to 15%. Additionally or alternatively, the dry pick-up may be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, or any wet pick-up range between any two of the wet pick-up values 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%.

[0052] As readily understood by those skilled in the art, regulating dry pick-up of the textile may be performed by adjusting wet pick-up or concentration(s) of treatment chemical(s). As exemplified in the working examples herein, using in treatment of synthetic textile a 10 wt % CA solution, a 10 wt % SHP solution and wet pick-up of 70%, dry pick-up for both CA and SHP is 7%.

[0053] In a further aspect, the present invention relates to use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile. The polycarboxylic acid is one or more selected from citric acid (CA), isocitric acid (ICA), tricarballylic acid (TCA) 1,2,4-butanetricarboxylic acid (BTRCA), 1,2,3,4-butanetetracarboxylic acid (BTCA), oxalic acid, tartaric acid, succinic acid, malic acid, malonic acid, glutamic acid, aspartic acid, glutaric acid, 1,3,5-pentanetricarboxylic acid, gluconic acid, mannaric acid, galactaric acid, maleic acid, and adipic acid, or a salt or a hydrate or an isomer thereof.

[0054] In an embodiment, in the use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile, the polycarboxylic acid is cured in the presence of a catalyst selected from sodium hypophosphite (SHP), monosodium phosphate (MSP), or any mixture thereof.

[0055] All of the embodiments disclosed herein in the context of the antimicrobial synthetic textile of the invention and the method for manufacturing an antimicrobial synthetic textile of the invention also apply to the use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile.

[0056] In a yet further aspect, the present invention relates to any item and/or product manufactured from the antimicrobial synthetic textile obtainable by the method of the invention or the synthetic textile comprising an antimicrobial finish. These include, but are not limited to items of clothing, furnishings, upholsteries, and products for healthcare and hospital use.

[0057] In an aspect, the invention relates to products manufactured from, containing or comprising the antimicrobial synthetic textile. The antimicrobial synthetic textile may be manufactured by the method of the invention. The product may be selected from clothing; footwear; personal protective equipment; accessories such as hats, scarves, gloves, belts and ties; bags; luggage; backpacks; towels; interior textiles such as bedding, cushions, throws, curtains, drapes, upholstery, floor and wall coverings and car interiors; sports and outdoor equipment, medical textiles such as wound dressings, bandages, masks, gloves and surgical gowns; toys; industrial products such as filters, conveyor belts, geotextiles, industrial fabrics, shade nets, crop covers, packaging materials, insulation materials, gaskets, seals, and tire cords; and electronic devices such as headphones, microphones and speakers.

[0058] As regards discoloration of textiles treated with polycarboxylic acids due to formation of colored degradation products, use of a polyol in the treatment solution may prevent yellowing of the textile. This is because the presence of a polyol may be expected to prevent the unwanted side-reaction producing unsaturated acids such as aconitic acid. Such polyols include, but are not limited to xylitol, sorbitol, glycerol and pentaerythritol. Also, use of BTCA, TBA and/or BTRCA as the polycarboxylic acid is believed to prevent or reduce formation of the yellow-colored side-products because these polycarboxylic acids form anhydrides upon heating without producing significant amounts of unsaturated acids.

[0059] In an embodiment, the antimicrobial synthetic textile of the invention and the method and the use of the invention involve a polyol selected from xylitol, sorbitol, glycerol, pentaerythritol, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, polyethylene glycol (PEG) 200, PEG 400, PEG 600, Tris(methylol)ethane, and any combination thereof. The polyol may be included in the treatment solution comprising polycarboxylic acid and catalyst i.e. the polyol is applied to the synthetic 10 extilee with the polycarboxylic acid and before curing to produce the antimicrobial finish.

[0060] In an embodiment, the polyol is included in the treatment solution at a concentration in the range of 0.1 to 5 wt-%, preferably 0.2 to 3 wt-%, more preferably 0.3 to 2 wt-%, even more preferably 0.5 to 1 wt-%, based on the total weight of the treatment solution. Additionally or alternatively, a polyol concentration of 0.1 wt-%, 0.2 wt-%, 0.3 wt-%, 0.4 wt-%, 0.5 wt-%, 0.6 wt-%, 0.7 wt-%, 0.8 wt-%, 0.9 wt-%, 1.0 wt-%, 1.1 wt-%, 1.2 wt-%, 1.3 wt-%, 1.4 wt-%, 1.5 wt-%, 1.6 wt-%, 1.7 wt-%, 1.8 wt-%, 1.9 wt-%, 2.0 wt-%, 2.5 wt-%, 3.0 wt-%, 3.5 wt-%, 4.0 wt-%, 4.5 wt-% or 5.0 wt-%, based on the total weight of the treatment solution, or a concentration range between any two of said concentrations may be used in the treatment solution.

[0061] The treatment solution may comprise further auxiliary components including essential oils that contain terpenes for antimicrobial efficacy and odor control (e.g. peppermint oil). Odor control may also be achieved by metal oxides. As readily appreciated by those skilled in the art, further auxiliary components may include surfactants to decrease surface tension of water, rheology modifiers to alter the rheology of the solution, antifoaming additives such as polydimethylsiloxanes to reduce foaming and additional biocides approved for use in textile industry. Surfactants can alleviate problems caused by hardness of water. Preferably, the surfactant is a bio-sourced surfactant such as a green non-ionic surfactant. A water-soluble polymer may act as a rheology modifier.

[0062] Polycarboxylic acids have several carboxylic groups each having their own pK_a value. For example, citric acid is a tricarboxlic acid having with pK_a values of 3.128, 4.761, and 6.396 at 25° C. The antimicrobially most efficient range for citric acid is below pH 3.1 where at least half of CA molecules have all three carboxylic groups are protonated i.e. CA is in H3A form. For example, at pH 4.7 none of CA is in H3A form but half of it is in H2A form and half in HA form. The same applies to other polycarboxylic acids at their own specific pK_a values.

[0063] We have surprisingly discovered that pH of the treatment solution affects quality of the resulting antimicrobial finish. Using a pH in the range of 2 to 7 in the treatment solution that is applied on a synthetic textile to manufacture a polycarboxylic acid treated synthetic textile produces the most durable finish. Optionally, the pH may be in the range of 2 to 6, or 2 to 5, or 2 to 4, or 2 to 3. As readily understood by those skilled in the art, regulating pH of the treatment solution may be performed with acids and/or bases.

[0064] GRAS (Generally-Recognized-as-safe) additives can safely be used for odor reduction and bacterial control on a textile material. A GRAS substance is a food substance that is not subject to premarket review and approval by FDA because it is generally recognized, by qualified experts, to be safe under the intended conditions of use. These are for instance citric acid, malic acid and their derivatives. Among GRAS substances there is a group of those which are listed as minimum risk pesticides, and which can therefore be claimed to have antimicrobial efficacy when used in textiles. Citric acid is included in this group.

[0065] Also, other nature-derived GRAS substances such as chitosan and chitosan derivatives are considered safe and green antimicrobial substances. Chitosan has a wide-spectrum antimicrobial activity based on quaternary nitrogen and is particularly effective at pH values below 6. Chitosan may produce a synergistic antimicrobial effect when combined with a polycarboxylic acid in all aspects of the invention such as the method for manufacturing an antimicrobial synthetic textile or antimicrobial textile or use according to the invention.

[0066] Citric acid is an Annex I (EU) listed active substance that is identified as a low-risk substance. Biocidal products containing such substances with low toxicity are eligible for a simplified authorization procedure in the EU. For instance, silver-based technologies are not considered as low risk substances as their mode of action is based on leaching which is basically “toxic-by-design”. Developing an antimicrobial textile finish is required to meet the adequate level of “Safe-by-Design” (SbD) strategy. The SbD concept refers to identifying the risks and uncertainties concerning humans and the environment at an early phase of the innovation process to minimize uncertainties, potential hazards and/or exposure. The SbD approach addresses the safety of the material/product and associated processes through the whole life cycle: from the Research and Development (R&D) phase to production, use, recycling and disposal. Citric acid is safe to environment and does not pose a danger to humans. It can be found naturally in fruits and vegetables, particularly in citrus fruits.

[0067] In an aspect, the method of the invention may comprise treating the antimicrobial synthetic textile with one or more additional textile treatment agents or textile treatment substances that improve properties of the textile.

[0068] In a further aspect, the antimicrobial synthetic textile of the invention may be treated with additional textile treatment agents or textile treatment substances that improve properties of the textile. Said synthetic textile thus comprises in addition to the antimicrobial finish a finishing with one or more additional textile treatment agents or textile treatment substances.

[0069] In a yet further aspect, the use of the invention i.e. the use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile may comprise treating the antimicrobial synthetic textile with one or more additional textile treatment agents or textile treatment substances that improve properties of the textile.

[0070] Such one or more additional agent(s) or substance(s) may be added to the treatment solution comprising a polycarboxylic acid and a catalyst that is cured to form the antimicrobial finishing. Additionally or alternatively, treating the textile with the additional agent(s) may be performed in a separate step that either precedes the antimicrobial finishing steps or is subsequent to them.

[0071] The additional textile treatment agent or textile treatment substance may be selected from one or more of anticrease agent, shrinkage control agent, fluorescent whitening agent, water repellent, oil repellent, self-cleaning agent, flame retardant, softener, odour absorber, odour controller, antibacterial agent, antifungal agent, antiviral agent, insect repellant, moisture managing agent, anti-static agent, anti-pilling agent, anti-slip agent, and UV-protecting agent.

[0072] In an embodiment, the antibacterial agent is chitosan.

[0073] Further provided are the following embodiments.

• • [0074] 1. A method for manufacturing an antimicrobial synthetic textile, comprising the steps of:
  • [0075] a) providing a treatment solution comprising a polycarboxylic acid and a catalyst;
  • [0076] b) applying the treatment solution on a synthetic textile to produce a polycarboxylic acid treated synthetic textile; and
  • [0077] c) curing the polycarboxylic acid treated synthetic textile;
  • [0078] wherein the polycarboxylic acid is one or more selected from citric acid (CA), isocitric acid (ICA), tricarballylic acid (TCA) 1,2,4-butanetricarboxylic acid (BTRCA), 1,2,3,4-butanetetracarboxylic acid (BTCA), oxalic acid, tartaric acid, succinic acid, malic acid, malonic acid, glutamic acid, aspartic acid, glutaric acid, 1,3,5-pentanetricarboxylic acid or a salt, a hydrate or an isomer thereof, and
  • [0079] wherein the catalyst is one or more selected from sodium hypophosphite (SHP), an SHP hydrate, monosodium phosphate (MSP), an MSP hydrate or any mixture thereof.
  • [0080] 2. The method of embodiment 1, wherein curing is performed at a temperature ranging from 150° C. to 180° C., or 150° C. to 175° C., or 160° C. to 175° C., or 1600 to 170° C., or 1500 to 170° C.
  • [0081] 3. The method of embodiment 1 or embodiment 2, wherein curing is performed for a period of time ranging from 30 to 180 seconds, or 30 to 150 seconds, or 30 to 120 seconds, or 60 to 120 seconds.
  • [0082] 4. The method of any one of the preceding embodiments 1-3, wherein the treatment solution has a pH in the range of 2 to 7, or 2 to 6, or 2 to 5, or 2 to 4, or 2 to 3.
  • [0083] 5. The method of any one of the preceding embodiments 1-4, wherein dry pick-up of polycarboxylic acid and/or catalyst is in the range of 3% to 12%, preferably in the range of 4% to 10% or 5% to 9%.
  • [0084] 6. The method of any one of the preceding embodiments 1-5, wherein the synthetic textile is selected from polyester; polyamide such as nylon; polyacrylonitrile such as acrylic and modacrylic; olefin; vinyon; polyethylene such as ultra-high-molecular-weight polyethylene (UHMWPE, UHMW), Dyneema and Spectra; elastane; vinylon; aramid such as Kevlar, Nomex and Twaron; polybenzimidazole (PBI); polyphenylene sulfide (PPS); polylactic acid (PLA); poly(p-phenylene-2,6-benzobisoxazole (PBO); Vectran; glass fibre or any mixture thereof.
  • [0085] 7. The method of any one of the preceding embodiments 1-6, wherein to produce the treatment solution, the polycarboxylic acid and catalyst are dissolved in a solvent selected from an aqueous solvent, water, alcohol, ether, ethyl acetate, ketone, DMSO or any mixture thereof.
  • [0086] 8. An antimicrobial synthetic textile produced according to the method of any one of embodiments 1 to 7.
  • [0087] 9. A synthetic textile comprising an antimicrobial finish comprising a polycarboxylic acid cured in the presence of a catalyst, wherein the polycarboxylic acid is one or more selected from citric acid (CA), isocitric acid (ICA), tricarballylic acid (TCA) 1,2,4-butanetricarboxylic acid (BTRCA), 1,2,3,4-butanetetracarboxylic acid (BTCA), oxalic acid, tartaric acid, succinic acid, malic acid, malonic acid, glutamic acid, aspartic acid, glutaric acid, 1,3,5-pentanetricarboxylic acid or a salt, a hydrate or an isomer thereof, and wherein the catalyst is one or more selected from sodium hypophosphite (SHP), a SHP hydrate, monosodium phosphate (MSP), an MSP hydrate or any mixture thereof.
  • [0088] 10. The synthetic textile of embodiment 9, wherein curing is performed at a temperature ranging from 150° C. to 180° C., or 150° C. to 175° C., or 160° C. to 175° C., or 1600 to 170° C., or 1500 to 170° C., optionally wherein curing is performed for a period of time ranging from 30 to 180 seconds, or 30 to 150 seconds, or 30 to 120 seconds, or 60 to 120 seconds.
  • [0089] 11. The synthetic textile of embodiment 9 or embodiment 10, wherein dry pick-up of polycarboxylic acid and/or catalyst is in the range of 3% to 12%, preferably in the range of 4% to 10% or 5% to 9%.
  • [0090] 12. The synthetic textile of any one of embodiments 9 to 11, wherein the synthetic textile is selected from polyester; polyamide such as nylon; polyacrylonitrile such as acrylic and modacrylic; olefin; vinyon; polyethylene such as ultra-high-molecular-weight polyethylene (UHMWPE, UHMW), Dyneema and Spectra; elastane; vinylon; aramid such as Kevlar, Nomex and Twaron; polybenzimidazole (PBI); polyphenylene sulfide (PPS); polylactic acid (PLA); poly(p-phenylene-2,6-benzobisoxazole (PBO); Vectran; glass fibre or a mixture thereof.
  • [0091] 13. Use of a polycarboxylic acid as an antimicrobial finish on a synthetic textile, wherein the polycarboxylic acid is one or more selected from citric acid (CA), isocitric acid (ICA), tricarballylic acid (TCA) 1,2,4-butanetricarboxylic acid (BTRCA), 1,2,3,4-butanetetracarboxylic acid (BTCA), oxalic acid, tartaric acid, succinic acid, malic acid, malonic acid, glutamic acid, aspartic acid, glutaric acid, 1,3,5-pentanetricarboxylic acid or a salt, a hydrate or an isomer thereof.
  • [0092] 14. The use of embodiment 13, wherein the polycarboxylic acid is cured in the presence of a catalyst, wherein the catalyst is one or more selected from sodium hypophosphite (SHP), a SHP hydrate, monosodium phosphate (MSP), an MSP hydrate or any mixture thereof.
  • [0093] 15. The use of embodiment 13 or 14, wherein the synthetic textile is selected from polyester; polyamide such as nylon; polyacrylonitrile such as acrylic and modacrylic; olefin; vinyon; polyethylene such as ultra-high-molecular-weight polyethylene (UHMWPE, UHMW), Dyneema and Spectra; elastane; vinylon; aramid such as Kevlar, Nomex and Twaron; polybenzimidazole (PBI); polyphenylene sulfide (PPS); polylactic acid (PLA); poly(p-phenylene-2,6-benzobisoxazole (PBO); Vectran; glass fibre or a mixture thereof.

[0094] Example 1 presents a method of antimicrobially finishing a synthetic textile with citric acid employing sodium hypophosphite as catalyst. The method involves a two-step heat treatment of separately drying and curing the textile.

[0095] Water-soluble treatment solution was prepared as follows. Citric acid (CAS No. 77-92-9) and sodium hypophosphite (SHP) monohydrate (CAS No. 10039-56-2) were in solid form when dissolved in distilled water in room temperature. The final concentrations were 10 wt % for citric acid and 10 wt % for SHP. Citric acid was dissolved first in and after all of the citric acid had visibly dissolved, SHP was added.

[0096] Polyester fabric samples were immersed in the 10 wt % citric acid, 10 wt % SHP working solution, swirled around for a minute and after that either padded to approximately 70% pick-up or dried straight after dipping. Wet samples were placed to stenter frame and firstly dried completely in 100° C. for 10 minutes and then cured in 150° C. for 90 seconds. After curing fabric samples were left to rehydrate overnight in room temperature and were then ready for further processing. The materials were rinsed thoroughly with tap water and then subjected to laundering. Laundering included either 0× or 10× wet-on-wet domestic laundering cycles at 40° C. Laundering was carried out according to 4N program of the ISO 6330 standard in an Electrolux Professional Wascator FOM71 CLS using the ECE-2 reference detergent. All samples were rinsed well in deionized water prior to analysis.

[0097] Determination of durability and resultant antibacterial protection of the treated fabrics was carried out through screening tests based on standard ISO 20743. In brief, pieces of treated polyester fabric (0.4 g) were inoculated with 3.6×10⁴ cells of Staphylococcus aureus. After 21-hour contact time, the surviving S. aureus cells were shaken-out from the sample pieces with 20 ml of tryptone soy broth supplemented with 0.07% lecithin and 0.5% Tween®. S. aureus cells were quantitated by plating a dilution series of the shake-out liquid on tryptone soy agar plates and counting colonies after 24-hour incubation.

[0098] Antibacterial activity value (A) was calculated according to formula [1]:

$\begin{array}{cc}A=\left({\mathrm{IgC}}_t-{\mathrm{IgC}}_0\right)-\left({\mathrm{IgT}}_t-{\mathrm{IgT}}_0\right)=F-G& \left[1\right]\end{array}$

where F is the growth value on the control specimen (F=(IgC_t−IgC₀); G is the growth value on the antibacterial testing specimen (G=(IgT_t−IgT₀); Ig C_t is the common logarithm of the number of bacteria obtained from control specimen after an 18 h to 24 h incubation; Ig C₀ is the common logarithm of the number of bacteria in the inoculum; Ig Ti is the common logarithm of the number of bacteria obtained from antibacterial testing specimen after an 18 h to 24 h incubation; Ig T₀ is the common logarithm of the number of bacteria in the inoculum. A values and data used for calculation of A is presented in Table 1.

TABLE 1
Data for antibacterial activity value (A) calculation for citric
acid and sodium hypophosphite (SHP) treated polyester fabric.
	Value	0x washed sample	10x washed sample
	C0 (control)	4.6	4.6
	Ct (control)	8.1	8.1
	T0 (sample)	4.6	4.6
	Tt (sample)	<2.3	<2.3
	F	3.5	3.5
	G	−2.3	−2.3
	A	5.8	5.8

[0099] The result was that both treated samples, both Ox and 10× washed, had an A value of 5.8 i.e. gave >5 log (>99.999%) reduction in S. aureus colony count compared to untreated control polyester fabric. The ISO 20743 (2021) standard gives the following reference values for efficacy of antibacterial property: log reduction <2=low antibacterial property; log reduction 2-3=significant antibacterial property; log reduction >3=strong antibacterial property. Therefore, the treated fabric had strong antibacterial property against Staphylococcus aureus even after 10 washing cycles.

[0100] Example 2 presents preparation of water-soluble treatment solution based on crosslinking agent, citric acid, and catalyst, sodium hypophosphite monohydrate; manufacture of polyester material with antimicrobial properties; and demonstration of antimicrobial properties of the manufactured polyester textile against Gram-positive and Gram-negative bacteria after various washing cycles.

[0101] To prepare the water-soluble treatment solution, solid form citric acid, anhydrous, (CA; CAS No. 77-92-9) and sodium hypophosphite monohydrate (SHP; CAS No. 10039-56-2) were dissolved in tap water at room temperature. The final concentrations were 9 wt % for CA and 9 wt % for SHP. Citric acid was dissolved first and after all CA had visibly dissolved, SHP was added. To investigate the effect of citric acid alone, a similar CA solution was prepared without adding SHP in the solution.

[0102] Polyester material with antimicrobial properties was manufactured by immersing polyester fabric samples in two different working solutions containing a) 9 wt % citric acid and 9 wt % sodium hypophosphite monohydrate or b) 9 wt % citric acid, swirled around for one minute and thereafter padded to approximately 70% pick-up. Wet samples were placed to stenter frame and dried and cured in one step, 90 seconds at 160° C. After curing fabric samples were left to rehydrate overnight at room temperature. The treated textile materials were rinsed thoroughly with tap water and then subjected to laundering. Laundering included either Ox, 10×, or 25× wet-on-wet domestic laundering cycles at 40° C. Laundering was carried out according to 4N program of the ISO 6330 standard (2021) in an Electrolux Professional Wascator FOM71 CLS using the ECE-2 reference detergent. All samples were rinsed well in deionized water prior to analysis.

[0103] Determination of durability and resultant antibacterial protection of the treated fabrics was carried out through screening tests based on the standard ISO 20743 (2021). Briefly, pieces of treated polyester fabric (0.4 g) were inoculated with either 4.5×10⁴ cells of Gram-positive Staphylococcus aureus (ATCC 6538) or 4.7×10⁴ cells of Gram-negative Klebsiella pneumoniae (ATCC 4352). After overnight contact time, the surviving bacterial cells were shaken-out from the sample pieces with 20 ml of tryptone soy broth supplemented with 0.07 wt % lecithin and 0.5 vol % Tween®. Bacterial cells were quantitated by plating a dilution series of the shake-out liquid on tryptone soy agar plates and counting colonies after overnight incubation.

[0104] Antibacterial activity value (A) was calculated similarly as in Example 1. A values and data used for calculation of A are presented in Tables 2 and 3.

TABLE 2
Data for antibacterial activity value (A) calculation
for Staphylococcus aureus (ATCC 6538).
	0x	0x	10x	10x	25x	25x
Value	CA + SHP	CA	CA + SHP	CA	CA + SHP	CA
C0 (control)	4.5	4.5	4.5	4.5	4.5	4.5
Ct (control)	7.4	7.4	7.4	7.4	7.4	7.4
T0 (sample)	4.5	4.5	4.5	4.5	4.5	4.5
Tt (sample)	<2.3	4.7	<2.3	6.3	<2.3	6.9
F	2.9	2.9	2.9	2.9	2.9	2.9
G	−2.2	0.2	−2.2	1.8	−2.2	2.4
A	>5.1	2.7	>5.1	1.1	>5.1	0.5
A %	>99.999	99.8	>99.999	92.7	99.999	68
CA = citric acid; SHP = sodium hypophosphite; 0x = 0x washed; 10x = 10x washed; 25x = 25 x washed.

TABLE 3
Data for antibacterial activity value (A) calculation
for Klebsiella pneumoniae (ATCC 4352).
	0x	0x	10x	10x	25x	25x
Value	CA + SHP	CA	CA + SHP	CA	CA + SHP	CA
C0 (control)	4.7	4.7	4.7	4.7	4.7	4.7
Ct (control)	8.0	8.0	8.0	8.0	8.0	8.0
T0 (sample)	4.7	4.7	4.7	4.7	4.7	4.7
Tt (sample)	<2.3	5.0	4.3	8.1	5.9	8.1
F	3.2	3.2	3.2	3.2	3.2	3.2
G	−2.4	0.2	−0.4	3.4	1.2	3.4
A	>5.7	3.0	3.7	−0.2	2.1	−0.2
A %	>99.999	99.9	>99.9	0	>99	0
CA = citric acid; SHP = sodium hypophosphite; 0x = 0x washed; 10x = 10x washed; 25x = 25 x washed.

[0105] The ISO 20743 standard (2021) gives the following reference values for efficacy of antibacterial property: log reduction <2=low antibacterial property; log reduction 2-3=significant antibacterial property; log reduction >3=strong antibacterial property. The result with Gram-positive S. aureus was that the samples treated with citric acid and sodium hypophosphite monohydrate had strong antimicrobial property (log reduction >3) as rinsed and also after 10 or 25 washing cycles. With CA alone, the rinsed sample had significant antimicrobial property (log reduction 2-3) but after 10 or 25 washing cycles there was only low antimicrobial property left in the samples. With the Gram-negative bacterium Klebsiella pneumoniae, the results were essentially the same except after 25 washing cycles, the samples treated with CA and SHP had significant, not strong, antimicrobial property.

[0106] Example 3 presents the effect of drying and curing temperature on the formation of antimicrobial properties on polyester textile.

[0107] To prepare the water-soluble treatment solution, solid form citric acid, anhydrous, (CA; CAS No. 77-92-9) and sodium hypophosphite monohydrate (SHP; CAS No. 10039-56-2) were dissolved in tap water at room temperature. The final concentrations were 9 wt % for CA and 9 wt % for SHP. Xylitol (CAS 87-99-0) was added in the treatment solution to a final concentration of 0.5 wt % to reduce yellowing of the textile samples. pH of the treatment solution was 3.0.

[0108] Polyester material with antimicrobial properties was manufactured by immersing polyester fabric samples in the treatment solution, swirling around for one minute and after that, padding to approximately 70% pick-up. Wet samples were placed to stenter frame and dried and cured in one step, 90 seconds at either 120° C., 130° C., 140° C., 150° C., 160° C., 170° C., or 180° C. After curing, fabric samples were left to rehydrate overnight at room temperature. The treated textile materials were rinsed thoroughly with tap water and then subjected to laundering. Laundering included 10× wet-on-wet domestic laundering cycles at 40° C. Laundering was carried out according to 4N program of the ISO 6330 standard (2021) in an Electrolux Professional Wascator FOM71 CLS using the ECE-2 reference detergent. All samples were rinsed well in deionized water prior to analysis.

[0109] Determination of durability and resultant antibacterial protection of the treated fabrics was carried out through screening tests based on the standard ISO 20743 (2021). Briefly, pieces of treated polyester fabric (0.4 g) were inoculated with 4.8×10⁴ cells of Gram-positive Staphylococcus aureus (ATCC 6538). After overnight contact time, the surviving bacterial cells were shaken-out from the sample pieces with 20 ml of tryptone soy broth supplemented with 0.07% lecithin and 0.5% Tween®. Bacterial cells were quantitated by plating a dilution series of the shake-out liquid on tryptone soy agar plates and counting colonies after overnight incubation.

[0110] Antibacterial activity value (A) was calculated similarly as in Example 1. A values and data used for calculation of A are presented in Table 4.

TABLE 4
Data for antibacterial activity value (A) calculation at different
curing temperatures. C0 and Ct were determined for untreated
control polyester fabric and T0 and Tt for the sample.
Value	120° C.	130° C.	140° C.	150° C.	160° C.	170° C.	180° C.
C0	4.8	4.8	4.8	4.8	4.8	4.8	4.8
Ct	7.1	7.1	7.1	7.1	7.1	7.1	7.1
T0	4.8	4.8	4.8	4.8	4.8	4.8	4.8
Tt	>7.3	>7.3	7.3	4.3	<2.3	2.6	5.5
F	2.3	2.3	2.3	2.3	2.3	2.3	2.3
G	>2.5	>2.5	2.5	−0.5	<−2.5	−2.2	0.7
A	<−0.2	<−0.2	−0.2	2.8	>4.8	4.5	1.6
A %	~0	~0	~0	99.8	>99.998	99.997	97.5

[0111] According to the results, strong antimicrobial activity (log reduction >3) against Gram-positive S. aureus was achieved when drying and curing step was done at either 160° C. or 170° C. Additionally, significant antimicrobial activity was achieved when drying and curing step was done at 150° C. and low antimicrobial activity was achieved when drying and curing step was done at 180° C. However, we expect that in larger scale industrial applications heat transfer to the fabric in an industrial dryer is more efficient than in laboratory scale experiments such as those in this Example. Thus, a lower temperature compared to drying and curing in laboratory scale is sufficient in industrial scale. A drying and curing temperature of 130° C. or 140° C. is likely sufficient.

[0112] As per visual inspection, no yellowing of the textile was observed even at 180° C. This is assumed to be influenced by the presence of the polyol xylitol in the samples.

[0113] Example 4 presents preparation of water-soluble treatment solution based on citric acid and either a) sodium hypophosphite monohydrate, or b) monosodium phosphate dihydrate as a reaction catalyst; manufacture of polyester material with antimicrobial properties; and demonstration of antimicrobial properties of the manufactured polyester textile against Gram-positive bacteria after various washing cycles.

[0114] Water-soluble treatment solution was prepared as follows: citric acid, anhydrous, (CA; CAS No. 77-92-9) and either a) sodium hypophosphite (SHP) monohydrate (CAS No. 10039-56-2), or b) monosodium phosphate (MSP) dihydrate (NaH₂PO₄·2H₂O; CAS No. 13472-35-0) were in solid form when dissolved in deionized water at room temperature. The final concentrations were 9 wt % for citric acid and either a) 9 wt % for SHP, or b) 13.5 wt % for NaH₂PO₄·2H₂O. pH of the treatment solution a) was 2.88 and b) 2.99.

[0115] Polyester material with antimicrobial properties was manufactured by immersing polyester fabric samples in two different working solutions containing a) 9 wt % citric acid (CA) and either a) 9 wt % SHP or b) 13.5 wt % NaH₂PO₄·2H₂O, swirled around for one minute and after that, padded to approximately 70% pick-up. Wet samples were placed to stenter frame and dried and cured in one step, 90 seconds at 160° C. After curing fabric samples were left to rehydrate overnight in room temperature and were then ready for further processing. The materials were rinsed thoroughly with tap water and then subjected to laundering similarly to Example 4.

[0116] Determination of durability and resultant antibacterial protection of the treated fabrics was carried out similarly to Example 4. The treated textile pieces were inoculated with 4.3×10⁴ cells of Gram-positive Staphylococcus aureus (ATCC 6538). After overnight contact time, the surviving bacterial cells were shaken-out from the sample pieces with 20 ml of tryptone soy broth supplemented with 0.07 wt % lecithin and 0.5 vol % Tween®. Bacterial cells were quantitated by plating a dilution series of the shake-out liquid on tryptone soy agar plates and counting colonies after overnight incubation.

[0117] Antibacterial activity value (A) was calculated similarly as in Example 1. A values and data used for calculation of A are presented in Table 5.

TABLE 5
Data for antibacterial activity value (A) calculation.
	0x	0x	10x	10x
Value	CA + SHP	CA + MSP	CA + SHP	CA + MSP
C0 (control)	4.3	4.3	4.3	4.3
Ct (control)	8.0	8.0	8.0	8.0
T0 (sample)	4.3	4.3	4.3	4.3
Tt (sample)	<2.3	<2.3	>2.3	>2.3
F	3.7	3.7	3.7	3.7
G	−2.0	−2.0	−2.0	−2.0
A	>5.7	>5.7	>5.7	>5.7
A %	>99.999	>99.999	>99.999	>99.999
CA = citric acid; SHP = sodium hypophosphite; MSP = monosodium phosphate; 0x = 0x washed; 10x = 10x washed.

[0118] The polyester fabric samples treated with citric acid and with either SHP or MSP as a reaction catalyst had strong antimicrobial property (log reduction >3) both before washing and after 10 washing cycles. Both catalysts therefore have similar activity.

[0119] Example 5 presents the effect of adding low molecular weight chitosan to the treatment solution on antimicrobial properties against Gram-positive bacteria.

[0120] The treatment solution was prepared essentially as in Example 2 except the final concentrations were 10 wt % for CA and 10 wt % for SHP, and additionally low molecular weight chitosan (LMW-CS; CAS No. 9012-76-4) was added to final concentration of 1 wt %. Treatment of polyester fabric samples and testing of their antimicrobial property was done essentially as described in Example 2, except in this case wet pick-up was approximately 63%, and the samples were dried and cured in two steps, first at 100° C. for 10 min and then at 160° C. for 90 seconds.

[0121] Antibacterial activity value (A) was calculated similarly as in Example 1. A values and data used for calculation of A is presented in Table 6.

TABLE 6
Data for antibacterial activity value (A) calculation.
	Value	0x washed sample	10x washed sample
	C0 (control)	4.6	4.6
	Ct (control)	7.9	7.9
	T0 (sample)	4.6	4.6
	Tt (sample)	<2.3	<2.3
	F	3.3	3.3
	G	−2.3	−2.3
	A	5.6	5.6
	A %	>99.999	>99.999

[0122] The result was that the treated samples, both Ox and 1Ox washed, gave >5 log (>99.999%) reduction in S. aureus colony count compared to untreated control polyester fabric. The presence of chitosan did not weaken the antimicrobial activity of CA. Chitosan may have an additive effect on antimicrobial activity of the treatment solution because it is known to be an antimicrobial agent against fungi and both Gram-negative and Gram-positive bacteria, and particularly chitosan derivatives also have activity against viruses.

[0123] Example 6 presents preparation of water-soluble treatment solution; manufacture of polyester material (100% PES; textile A and B) with antifungal properties; and demonstration of antifungal properties of the manufactured polyester textiles against the fungus Aspergillus brasiliensis after several washing cycles. Samples A and B were polyester textiles from two different manufacturers.

[0124] The treatment solution was prepared essentially as In Example 2 except sorbitol (CAS No. 50-70-4) was added to a final concentration of 0.6 wt % and pH of the solution was adjusted to 2.9. Treatment and laundering of polyester fabric samples A and B was done essentially as described in Example 1.

[0125] Determination of durability and resultant antifungal protection of the treated fabrics was carried out through a screening test based on the standard ISO 13629-2. In brief, pieces of treated polyester fabric (0.4 g) were inoculated with 2.0×10⁴ spores of Aspergillus brasiliensis (ATCC 16404). After 44-hour contact time, the surviving A. brasiliensis spores were shaken-out from the sample pieces with 20 ml of tryptone soy broth supplemented with 0.07% lecithin and 0.5% Tween®. A. brasiliensis spores were quantitated by plating a dilution series of the shake-out liquid on Sabouraud dextrose agar plates and counting fungal colonies after 48-hour incubation. Antifungal activity value (A) was calculated as instructed in the standard ISO 13629-2, essentially similarly as the antibacterial activity value in the Example 1. Antifungal (A) values and data used for calculation of A is presented in Table 7.

TABLE 7
Data for antifungal activity value (A) calculation
for Aspergillus brasiliensis (ATCC 16404).
	Textile A	Textile A	Textile B	Textile B
Value	0x	10x	0x	6x
C0 (control)	4.3	4.3	4.3	4.3
Ct (control)	5.6	5.6	5.3	5.3
T0 (sample)	4.3	4.3	4.3	4.3
Tt (sample)	4.2	3.6	3.8	3.8
F	1.3	1.3	1.0	1.0
G	−0.1	−0.7	−0.5	−0.5
A	1.4	1.9	1.5	1.5
A %	96.1	98.8	96.9	96.9
0x = 0x washed; 6x = 6x washed; 10x = 10x washed.

[0126] Based on criteria for antifungal efficacy given in the standard ISO 13629-2, both treated 100% polyester textiles (A and B) were fungistatic with small effect, both as treated and after 10× or 6× laundering cycles. As per visual inspection, no yellowing of the textile was observed. This is assumed to be influenced by the presence of the polyol sorbitol in the samples.

[0127] Example 7 presents preparation of water-soluble treatment solution; manufacture of two polyester/elastane blend textiles (PES/EA 88/12 and PES/EA 92/8) with antibacterial properties; and demonstration of antibacterial properties of the manufactured synthetic blend textiles against Staphylococcus aureus after several washing cycles.

[0128] The treatment solution was prepared similarly as in Example 6I. Treatment and laundering of the synthetic blend textile samples were done essentially as described in Example 1.

[0129] Determination of durability and resultant antibacterial protection of the treated fabrics, and calculation of the Antibacterial activity value (A) were done similarly to Example 1.

[0130] The antibacterial (A) values and data used for calculation of A are presented in Table 8.

TABLE 8
Data for antibacterial activity value (A) calculation
for Staphylococcus aureus (ATCC 6538).
		PES/EA	PES/EA	PES/EA	PES/EA
		88/12	88/12	92/8	92/8
	Value	0x	8x	0x	8x
	C0 (control)	4.4	4.4	4.4	4.4
	Ct (control)	8.4	8.4	8.2	8.2
	T0 (sample)	4.4	4.4	4.4	4.4
	Tt (sample)	4.9	5.9	<3.3	5.1
	F	4.0	4.0	3.8	3.8
	G	0.6	1.6	−1.1	0.8
	A	3.5	2.5	>4.9	3.1
	A %	99.96	99.7	>99.998	99.91
	0x = 0x washed; 8x = 8x washed.

[0131] The treated synthetic polyester/elastane blend textiles had strong antibacterial property against Staphylococcus aureus as treated, and either significant or strong antibacterial property after 8 laundering cycles. As per visual inspection, no yellowing of the textile was observed. This is assumed to be influenced by the presence of the polyol sorbitol in the samples.

[0132] Example 8 presents a method of antimicrobially finishing a synthetic 100% polyester textile with 1,2,3,4-butanetetracarboxylic acid employing sodium hypophosphite as catalyst. The method involves a two-step heat treatment of separately drying and curing the textile.

[0133] 1,2,3,4-butanetetracarboxylic acid (BTCA, CAS No. 1703-58-8), sodium hypophosphite monohydrate (SHP, CAS No. 10039-56-2), and xylitol (CAS No. 87-99-0) were dissolved in deionized water at room temperature. The final concentrations were 9% for BTCA, 9% for SHP, and 0.5% for xylitol. pH of the treatment solution was adjusted to 3.0 by adding a sufficient amount of 1 mol/L sodium hydroxide solution (NaOH, CAS No. 1310-73-2).

[0134] Polyester fabric (100% PES) samples were immersed in the treatment solution containing 9% BTCA, 9% SHP, and 0.5% xylitol, swirled around for one minute and after that, padded to approximately 70% wet pick-up. Wet samples were placed to stenter frame and firstly dried completely at 100° C. for 5 minutes and then cured at 150° C. for 90 seconds. To test laundering durability of the treatment, a subset of the prepared samples was washed ten times, essentially as described in Example 1.

[0135] Determination of durability and resultant antibacterial protection of the treated fabrics was carried out similarly to Example 1. The treated textile pieces were inoculated with 2.3×10⁴ cells of Gram-positive Staphylococcus aureus (ATCC 6538). The contact time of the antimicrobial test was 24 hours.

[0136] Antibacterial activity value (A) was calculated similarly as in Example 1. A values and data used for calculation of A are presented in Table 9.

TABLE 9
Data for antibacterial activity value (A) calculation
for Staphylococcus aureus (ATCC 6538).
		BTCA + SHP	BTCA + SHP
	Value	0x	10x
	C0 (control)	4.4	4.4
	Ct (control)	8.0	8.0
	T0 (sample)	4.4	4.4
	Tt (sample)	<2.3	6.9
	F	3.6	3.6
	G	−2.1	2.5
	A	>5.6	1.1
	A %	>99.999	92
	BTCA = 1,2,3,4-butanetetracarboxylic acid; SHP = sodium hypophosphite monohydrate; 0x = 0x washed; 10x = 10x washed.

[0137] According to the results, strong antimicrobial property (ISO 20743 criteria: log reduction >3) against Gram-positive S. aureus was achieved by treating the 100% PES textile with a solution containing 9% BTCA, 9% SHP and 0.5% xylitol. After 10× laundering cycles, there was 92% less bacterial cells on the treated and washed sample than on the untreated sample of the same textile. As per visual inspection, no yellowing of the textile was observed. This is assumed to be influenced by the presence of the polyol xylitol in the samples.

[0138] Example 9 presents antimicrobially finishing a synthetic 100% polyester textile with tricarballylic acid employing sodium hypophosphite as catalyst. The finishing method involves a one-step heat treatment of drying and curing the textile.

[0139] Tricarballylic acid (TCA, CAS No. 99-14-9) and sodium hypophosphite monohydrate (SHP, CAS No. 10039-56-2) were dissolved in deionized water at room temperature. The final concentrations were 8.25% for TCA and 9% for SHP.

[0140] Polyester fabric (100% PES) samples were immersed in the treatment solution containing 8.25% TCA and 9% SHP, swirled around for one minute and after that, padded to approximately 70% wet pick-up. Wet samples were placed to stenter frame and heat-treated for drying and curing at 160° C. for 90 seconds. After curing, the fabric samples were rinsed thoroughly with tap water and left to rehydrate overnight in room temperature.

[0141] Determination of resultant antibacterial protection of the treated fabrics was carried out similarly to Example 1. The treated textile pieces were inoculated with 5.1×10⁴ cells of Gram-positive Staphylococcus aureus (ATCC 6538). Contact time of the antimicrobial test was 24 hours.

[0142] Antibacterial activity value (A) was calculated similarly as in Example 1. A values and data used for calculation of A are presented in Table 10.

TABLE 10
Data for antibacterial activity value (A) calculation
for Staphylococcus aureus (ATCC 6538).
	Value	TCA + SHP
	C0 (control)	4.8
	Ct (control)	8.0
	T0 (sample)	4.8
	Tt (sample)	<2.3
	F	3.3
	G	−2.5
	A	>5.7
	A %	>99.999
	TCA = tricarballylic acid; SHP = sodium hypophosphite monohydrate.

[0143] According to the results, strong antimicrobial property (ISO 20743: log reduction >3) against Gram-positive S. aureus was achieved by treating the 100% PES textile with a solution containing 8.25% TCA and 9% SHP.

[0144] It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.