Antibacterial fiber structure and method for producing same

Abstract

In order to provide an antibacterial fiber structure that exhibits excellent antibacterial properties, is configured to suppress the risk of skin sensitization, exhibits excellent washing durability, and is also excellent in cost, and to provide a method for producing this antibacterial fiber structure, this antibacterial fiber structure is configured such that an aromatic carboxylic acid (A) is fixed to the fiber structure, the fiber structure contains synthetic fibers, and the content ratio of the aromatic carboxylic acid (A) with respect to the fiber structure is 0.25-10 mass%.

Description

Antibacterial Fiber Structure and Method for Producing the Same

[0001] The present invention relates to an antibacterial fiber structure in which antibacterial properties are imparted to a fiber structure, and a method for producing the same.

[0002] In recent years, due to the increasing awareness of hygiene and health, many fiber products around us, such as clothing, towels, bedding, etc., have been provided with antibacterial and antifungal properties. However, since many antibacterial agents are difficult to chemically bond to fibers, most of the fiber products with antibacterial properties are only obtained by coating and adhering the antibacterial agent to the fiber surface with a binder such as resin. For this reason, those with high antibacterial properties have a problem that the amount of binder used increases and the texture of the fiber is impaired. In addition, when the fiber product is repeatedly washed, the antibacterial agent easily falls off from the fiber surface together with the binder, so there is also a problem that the antibacterial property tends to decrease each time it is washed. Also, it may be considered to initially contain the antibacterial agent in the fiber at a high concentration in anticipation of the decrease in antibacterial property due to washing, but the use of a high concentration of antibacterial agent has risks of skin damage such as skin irritation and risks of fiber discoloration, which is not preferable.

[0003] On the other hand, in synthetic fibers, in order to obtain washing durability, there are also products in which an antibacterial agent is kneaded into the fiber itself and spun, but there are extremely few antibacterial agents that can withstand such kneading and spinning temperatures (300 °C or higher in the case of polyester), and since highly heat-resistant inorganic antibacterial agents do not bleed to the fiber surface when encapsulated in synthetic fibers, there is a problem that sufficient antibacterial properties cannot be obtained.

[0004] Incidentally, as a technique for improving the washing durability by examining the composition of an antibacterial treatment agent for imparting an antibacterial agent to a fiber, for example, Patent Documents 1, 2, etc. can be cited.

[0005] Patent Document 1 discloses a method of attaching antibacterial components such as organic iodine compounds and thiazole compounds to fibers using a binder to provide washing durability. Patent Document 2 discloses a method of attaching antibacterial components such as nonionic surfactants having an HLB of 10 to 17 to fibers by heat treatment using a binder to provide washing durability.

[0006] Meanwhile, research is also underway on antibacterial agents that are gentle on human skin. For example, Patent Document 3 discloses an antibacterial composition containing benzoate salts together with polyvinyl alcohol as an antibacterial agent that is gentle on human skin, and textile products are listed as an application for the antibacterial composition.

[0007] However, the antibacterial agent in Patent Document 3 is required to be water-soluble because it is used by spraying it with an antibacterial sprayer. For this reason, the antibacterial agents actually disclosed are benzoates or hydroxybenzoic acid esters, and there is no disclosure of using aromatic carboxylic acids, which have conventionally been considered to have problems with stability and water solubility, as antibacterial agents for textile products. Furthermore, Patent Document 3 does not take into consideration wash durability.

[0008] Japanese Patent Publication No. 2005-154965, Japanese Patent Publication No. Hei 11-335202, Japanese Patent Publication No. 2022-11323

[0009] These technologies either rely on using a resin binder to attach antibacterial agents to fibers or do not consider wash durability, so the aforementioned problems remain, and their resolution is desired. Methods for fixing antibacterial agents to fibers without using a resin binder have also been investigated, but in order to exhibit sufficient antibacterial activity, it is necessary to use a predetermined amount of expensive antibacterial agents (e.g., isothiazole-based antibacterial agents, iodine-based antibacterial agents, etc.), so there is room for improvement in terms of cost.

[0010] This invention was made to address these challenges and provides an antibacterial fiber structure and a method for producing the same, which exhibits excellent antibacterial properties despite using safe components, does not cause skin sensitization, shows excellent washing durability, and is also cost-effective.

[0011] To address the aforementioned problems, the present invention has the following embodiments: [1] An antibacterial fiber structure in which an aromatic carboxylic acid (A) is fixed to a fiber structure, the fiber structure contains synthetic fibers, and the content of the aromatic carboxylic acid (A) in relation to the fiber structure is 0.25 to 10% by mass. [2] An antibacterial fiber structure in which an aromatic carboxylic acid (A) and an isothiazole-based antibacterial agent (B) and / or an iodine-based antibacterial agent (C) are fixed to a fiber structure, the fiber structure contains synthetic fibers, the content of the aromatic carboxylic acid (A) relative to the fiber structure is 0.1 to 10% by mass, if the isothiazole-based antibacterial agent (B) is fixed to the fiber structure, the content of the isothiazole-based antibacterial agent (B) relative to the fiber structure is 0.003 to 0.1% by mass, and if the iodine-based antibacterial agent (C) is fixed to the fiber structure, the content of the iodine-based antibacterial agent (C) relative to the fiber structure is 0.1 to 1% by mass. [3] An antimicrobial fiber structure according to [1] or [2], wherein the antimicrobial activity values ​​against Staphylococcus aureus and Klebsiella pneumoniae (according to JIS L1902:2015) after 10 washes at 40°C (according to JIS L0217-103) are both equal to or greater than the growth value F of the standard fabric. [4] An antimicrobial fiber structure according to [2] or [3], wherein the isothiazole antimicrobial agent (B) is a benzoisothiazoline derivative. [5] An antimicrobial fiber structure according to any one of [2] to [4], wherein the iodine antimicrobial agent (C) is 3-iodo-2-propynyl butylcarbamate. [6] An antimicrobial fiber structure according to any one of [1] to [5], wherein the aromatic carboxylic acid (A) is benzoic acid. [7] A method for producing an antimicrobial fiber structure according to any one of [1] to [6], wherein the aromatic carboxylic acid (A) is fixed to the fiber structure by impregnating the fiber structure containing synthetic fibers with an antimicrobial treatment solution containing the aromatic carboxylic acid (A) and performing a heat treatment at 90°C to 200°C.[8] A method for producing an antimicrobial fiber structure according to any one of [2] to [6], comprising impregnating a fiber structure containing synthetic fibers with an antimicrobial treatment solution containing the aromatic carboxylic acid (A) and the isothiazole-based antimicrobial agent (B) and / or the iodine-based antimicrobial agent (C), and performing a heat treatment at 90°C to 200°C to fix the aromatic carboxylic acid (A) and the isothiazole-based antimicrobial agent (B) and / or the iodine-based antimicrobial agent (C) to the fiber structure. [9] The method for producing an antimicrobial fiber structure according to [7] or [8], wherein the heat treatment is a heat treatment at 100 to 200°C under normal pressure.

[10] The method for producing an antimicrobial fiber structure according to [7] or [8], wherein the heat treatment is a heat treatment at 90 to 150°C under pressure.

[0012] In this specification, when we use the expression "Y to Z" (where Y and Z are any numbers), unless otherwise specified, it includes the meaning of "greater than or equal to Y and less than or equal to Z," as well as the meaning of "preferably greater than Y" or "preferably less than Z."

[0013] In this specification, "x and / or y (where x and y are any configuration)" means at least one of x and y, and can mean x only, y only, or x and y.

[0014] In this specification, the numerical ranges described in stages may be arbitrarily combined with the upper or lower limits of the numerical ranges in any stage. Furthermore, in the numerical ranges described herein, the upper or lower limits may be replaced with the values ​​shown in the examples.

[0015] In other words, the antibacterial fiber structure of the present invention achieves excellent antibacterial properties by using a specific amount of aromatic carboxylic acid, eliminating the need to use large amounts of highly effective antibacterial agents. This reduces the risk of skin sensitization and fiber discoloration, resulting in a high-quality product. Furthermore, by using aromatic carboxylic acids in combination with isothiazole-based and / or iodine-based antibacterial agents, the synergistic effect of these agents allows for antibacterial effects at lower concentrations compared to using each agent individually. This avoids problems that occur when using large amounts of highly effective antibacterial agents (such as fiber discoloration, reduced texture, and skin sensitization risk), and also reduces the amount of expensive antibacterial agents used, resulting in cost savings.

[0016] Furthermore, in this invention, since the aromatic carboxylic acid and the like are directly fixed to the fibers without using a resin binder, it has excellent washing durability and can maintain excellent antibacterial properties even after repeated washing.

[0017] Furthermore, according to the method for producing antibacterial fiber structures of the present invention, the antibacterial fiber structures can be efficiently manufactured using conventional fiber processing equipment such as dyeing devices.

[0018] This is a schematic diagram illustrating an example of a method for producing the antibacterial fiber structure of the present invention. This is a schematic diagram illustrating another example of a method for producing the antibacterial fiber structure of the present invention.

[0019] Next, embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

[0020] Traditionally, aromatic carboxylic acids have been used as food additives, such as antimicrobial or preservative agents, due to their high safety. However, among aromatic carboxylic acids, only aromatic carboxylic acid salts such as sodium benzoate and potassium benzoate, and aromatic carboxylic acid esters such as methyl p-hydroxybenzoate and butyl p-hydroxybenzoate are commonly used as antimicrobial or preservative agents. Aromatic carboxylic acids themselves are only used as plasticizers for resins under the Food Sanitation Law and are not typically used as antimicrobial agents for resins (fibers). This is because aromatic carboxylic acids are less soluble in water than aromatic carboxylic acid salts, making them less suitable for use as antimicrobial or preservative agents, and aromatic carboxylic acid esters with a molecular weight of 150 or more are not easily fixed to resins.

[0021] On the other hand, as mentioned above, when using water-soluble aromatic carboxylic acid salts or aromatic carboxylic acid esters that are not easily fixed to resins on fibers, they will fall off during washing if left as is, so it is necessary to use a binder to maintain wash durability. The inventors of this invention conceived the idea that aromatic carboxylic acids, which are used as additives in resins, could be fixed to synthetic fibers using a special processing method, thereby fixing them to fiber structures without the use of a binder, and conducted further research. As a result, they found that by fixing a specific amount of aromatic carboxylic acid to a fiber structure having synthetic fibers, wash durability can be imparted, contrary to conventional technology, and excellent antibacterial properties can be continuously exhibited.

[0022] Furthermore, the inventors have discovered that by using aromatic carboxylic acids in combination with isothiazole-based antibacterial agents and / or iodine-based antibacterial agents, the synergistic effect of these agents allows for even lower concentrations to be used compared to when each is used alone. In other words, according to the present invention, the amount of expensive isothiazole-based antibacterial agents, iodine-based antibacterial agents, etc. can be reduced, resulting in cost advantages, as well as reduced risks of discoloration and skin sensitization.

[0023] <Fiber Structures> First, the fiber materials of the fiber structures targeted by the present invention include synthetic resins such as polyester resins, polyamide resins, acrylic resins, and polyurethane resins; synthetic resins mixed with components other than synthetic resins (such as metals and inorganic substances); composites thereof; and synthetic fibers obtained from mixtures thereof. Natural fibers such as cotton, linen, rayon, wool, and silk (including regenerated fibers) may also be used. Furthermore, blends of the aforementioned synthetic fibers and natural fibers may also be used.

[0024] Among these, it is particularly preferable to target polyester fibers (including those consisting solely of polyester fibers) that mainly use polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polylactic acid resin, which are in high demand as antibacterial products and whose wash durability is a concern, as well as blended products (mixed fibers, blended fabrics) of polyester fibers and other fibers.

[0025] The forms of fiber structures made from the aforementioned fiber material include threads, strings, ropes, and fabrics (woven fabrics, knitted fabrics, nonwoven fabrics). Furthermore, fiber products made by combining the aforementioned fiber material with other materials (such as rubber for clothing, sewing threads, and films) are also included in the definition of "fiber structures" covered by this invention. Examples of such fiber products include bedding (curtains, sheets, towels, futons, futon stuffing, mats, carpets, pillowcases, etc.), clothing (coats, suits, sweaters, blouses, shirts, underwear, hats, masks, socks, gloves, etc.), and uniforms (lab coats, work clothes, school uniforms, etc.) that are commonly used in households.

[0026] In addition to household use, examples of widespread use include nursing care sheets, shower curtains, car seats, seat covers, interior materials such as ceiling materials, tents, insect and bird netting, partition sheets, air conditioning filters, vacuum cleaner filters, masks, tablecloths, desk mats, aprons, wallpaper, and wrapping paper. Furthermore, medical supplies (medical beds, wheelchairs, sterile bags, sterile sheets, etc.) and hygiene products (bandages, cleaning brushes, disposable masks, etc.) are also examples of widespread use.

[0027] In particular, the fiber structure of the present invention possesses antibacterial properties with excellent washing durability, making it suitable for application to linen supply products (surgical gowns, lab coats, pajamas, sheets, etc.) that are repeatedly washed and used in medical and nursing care facilities.

[0028] Next, we will explain the aromatic carboxylic acids to be included in the aforementioned fiber structure.

[0029] <Aromatic Carboxylic Acid (A)> The aromatic carboxylic acid (A) is preferably one with a molecular weight of less than 150, and among these, benzoic acid, phthalic acid, and salicylic acid are preferred, with benzoic acid being more preferable due to its superior safety and cost-effectiveness. Note that aromatic carboxylic acid (A) does not include aromatic carboxylic acid esters or aromatic carboxylic acid salts.

[0030] When the aromatic carboxylic acid (A) is used alone, the content of the aromatic carboxylic acid relative to the entire fiber structure must be 0.25 to 10% by mass, and from the viewpoint of antibacterial effect, it is preferably 1 to 10% by mass, and more preferably 3 to 10% by mass.

[0031] When the aromatic carboxylic acid (A) is used together with an isothiazole-based antimicrobial agent (B) and / or an iodine-based antimicrobial agent (C), the content of the aromatic carboxylic acid relative to the entire fiber structure is required to be 0.1 to 10% by mass, preferably 0.1 to 5% by mass, and more preferably 0.4 to 3% by mass, in order to find an excellent balance between antimicrobial effect and cost.

[0032] <Isothiazole-based antimicrobial agent (B)> In the present invention, examples of isothiazole-based antimicrobial agents (B) that can be used together with the aromatic carboxylic acid (A) include isothiazoline derivatives and benzoisothiazoline derivatives. Examples of isothiazoline derivatives include 2-methyl-4-isothiazolin-3-one, 2-butyl-4-isothiazolin-3-one, 4-(n-octyl)isothiazolin-3-one, 4-methyl-5-chloroisothiazolin-3-one, 4-methylisothiazolin-3-one, and 4,5-dichloro-4-cyclohexylisothiazolin-3-one.

[0033] Examples of the benzoisothiazoline derivatives include 1,2-benzoisothiazoline-3-one, 2-butyl-1,2-benzoisothiazoline-3-one, and 4,5-benzoisothiazoline-3-one.

[0034] These isothiazole antimicrobial agents (B) can be used individually or in combination of two or more. Among these, it is particularly preferable to use benzoisothiazoline derivatives, and especially preferable to use 1,2-benzoisothiazoline-3(2H)-one (hereinafter abbreviated as "BIT") and 2-butyl-1,2-benzoisothiazoline-3(2H)-one (hereinafter abbreviated as "BBIT"), with the use of BIT being optimal.

[0035] When the isothiazole-based antimicrobial agent (B) is used alone, it is usually necessary to include more than 0.2% by mass of the total fiber structure to exhibit effective antimicrobial activity. However, there is a risk of skin sensitization occurring at concentrations exceeding 0.1% by mass (according to data from the National Institute of Technology and Evaluation as of December 26, 2022).

[0036] Therefore, in the present invention, when using the isothiazole-based antibacterial agent (B), the content of the isothiazole-based antibacterial agent (B) relative to the entire fiber structure is preferably 0.003 to 0.1% by mass, more preferably 0.005 to 0.05% by mass, and even more preferably 0.01 to 0.04% by mass. Within this range, by combining the isothiazole-based antibacterial agent (B) with the aromatic carboxylic acid (A), it is possible to exhibit antibacterial properties through a remarkable synergistic effect while ensuring safety. Furthermore, the content ratio of the isothiazole-based antibacterial agent (B) to the aromatic carboxylic acid (A) [(B) / (A)] is usually set to 0.0003 to 0.25 by mass, preferably 0.001 to 0.05, and more preferably 0.01 to 0.05. Setting the ratio [(B) / (A)] within the above range is preferable in that it provides an excellent balance between antibacterial effect and cost.

[0037] The remarkable synergistic antibacterial effect obtained by the above-mentioned combination of the present invention is thought to be due to the following complex action. Specifically, the antibacterial mechanism of the isothiazole antibacterial agent (B) is inhibition of protein synthesis, inhibition of cell membrane synthesis, inhibition of thiol enzymes, and inhibition of TCA cycle enzymes, while the antibacterial mechanism of the iodine antibacterial agent (C) is protein denaturation and inhibition of enzyme function, while the antibacterial mechanism of the aromatic carboxylic acid (A) is destruction of DNA and RNA strands, membrane dysfunction, and inhibition of enzyme activity. Therefore, it is thought that a remarkable synergistic effect is exerted by using these components with different mechanisms of action in combination. Furthermore, it is thought that the above complex mechanism of action is equally effective not only for antibacterial properties but also for antifungal properties, so the present invention can be expected to have excellent antifungal properties against mold as well.

[0038] <Iodine-based antimicrobial agent (C)> In the present invention, examples of the iodine-based antimicrobial agent (C) that can be used together with the aromatic carboxylic acid (A) include diiodomethyl-p-tolylsulfone and 3-iodo-2-propynyl=N-butylcarbamate, and among these, 3-iodo-2-propynyl=N-butylcarbamate (hereinafter abbreviated as "IPBC") is preferred in terms of effectiveness.

[0039] Similarly, in the present invention, when the iodine-based antimicrobial agent (C) is used, the content of the iodine-based antimicrobial agent (C) in relation to the entire fiber structure is preferably set to 0.1 to 1% by mass, and more preferably to 0.2 to 1% by mass. The content ratio of the iodine-based antimicrobial agent (C) to the aromatic carboxylic acid (A) [(C) / (A)] is usually set to 0.01 to 5 by mass, preferably to 0.05 to 3, and more preferably to 0.1 to 1. Setting the ratio [(C) / (A)] within the above range is preferable in that it provides an excellent balance between antimicrobial effect and cost.

[0040] That is, by using the aromatic carboxylic acid (A) in combination with the isothiazole-based antibacterial agent (B) and / or the iodine-based antibacterial agent (C), even when the contents of the aromatic carboxylic acid (A), the isothiazole-based antibacterial agent (B) and / or the iodine-based antibacterial agent (C) are at very low concentrations compared to the case where they are individually applied to the fiber, excellent antibacterial properties can be exhibited, which is preferable. More preferably, all of the aromatic carboxylic acid (A), the isothiazole-based antibacterial agent (B), and the iodine-based antibacterial agent (C) are used.

[0041] When the isothiazole-based antibacterial agent (B) and the iodine-based antibacterial agent (C) are used, the ratio [(C) / (B)] thereof is usually set to 1 to 500 on a mass basis, and preferably set to 10 to 200, more preferably set to from 10 to 100, from the viewpoint of safety.

[0042] The antibacterial fiber structure of the present invention can be obtained, for example, by combining the aromatic carboxylic acid (A) with, if necessary, the isothiazole-based antibacterial agent (B) and / or the iodine-based antibacterial agent (C) and the like in the following manner.

[0043] <Manufacturing method of antibacterial fiber structure> (1). Preparation of antibacterial treatment liquid First, an antibacterial treatment liquid for imparting antibacterial properties to the fiber structure is prepared. This antibacterial treatment liquid can be obtained by dissolving or dispersing the aromatic carboxylic acid (A) and, if necessary, the isothiazole-based antibacterial agent (B) and / or the iodine-based antibacterial agent (C) in a liquid serving as a solvent or a dispersion medium.

[0044] As the liquid serving as the solvent or the dispersion medium, water is usually used. Examples of water include tap water, soft water, ion-exchanged water, pure water, purified water, etc. Among them, soft water, ion-exchanged water, and purified water are preferably used. These may be used alone or in combination of two or more.

[0045] Also, an organic solvent can be used together with the water or in place of the water. Examples of the organic solvent include ethanol, isopropanol, N,N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, butylene glycol, diethylene glycol, dipropylene glycol, diethylene glycol monobutyl ether, and the like. These can be used alone or in combination of two or more kinds.

[0046] In addition, in the antibacterial treatment liquid used in the present invention, together with the aromatic carboxylic acid (A) and, if necessary, the isothiazole-based antibacterial agent (B) and / or the iodine-based antibacterial agent (C), further, in order to improve antibacterial properties and durability of effects, etc., for example, fiber processing aids, dispersants, deodorants, preservatives, fragrances, oily components, thickeners, moisturizers, pigments, pH adjusters, ceramides, sterols, antioxidants, singlet oxygen scavengers, ultraviolet absorbers, whitening agents, anti-inflammatory agents, other antibacterial agents, antiviral agents, and other known optional components can be blended. These can be used alone or in combination of two or more kinds.

[0047] However, when other antibacterial agents and / or antiviral agents are used with the intention of antibacterial effects and / or antiviral effects, from the gist of the present invention, the content of the other antibacterial agents and / or antiviral agents with respect to the entire fiber structure is preferably 10% by mass or less, more preferably 1% by mass or less, and still more preferably 0.1% by mass or less.

[0048] The fiber processing aids are used for the purpose of preventing abnormalities such as discoloration, hardening, and shrinkage of the fiber structure according to the type of fiber, and suppressing the decrease in antibacterial properties. Examples include antistatic agents, flame retardants, softeners, fixers, antifouling agents, leveling agents, fluorescent brighteners, swelling agents, penetrants, emulsifiers, sequestering agents, leveling agents, precipitation inhibitors, migration inhibitors, carriers, resist agents, anti-wrinkle agents, texture improvers, and the like.

[0049] For example, when processing blends of polyester fibers with natural fibers such as cotton, rayon, wool, and silk, or when processing blends of polyester fibers with polyamide, acrylic, and polyurethane fibers, depending on the processing temperature and time, fibers other than polyester fibers may undergo abnormalities such as discoloration, hardening, or shrinkage due to the action of cations such as isothiazole antibacterial agents (B), or their antibacterial properties may decrease or be lost. Therefore, in order to prevent such situations, it is preferable to use the aforementioned fixatives, uniforming agents, slow dyeing agents, fluorescent whitening agents, etc., as auxiliary agents.

[0050] The fixing agent used varies depending on the dye, but examples include polycationic compounds, polyamine compounds, and phenolic compounds.

[0051] Furthermore, examples of the uniforming agent and slowing agent include nonionic surfactants such as alkyl ether type, polycyclic phenyl ether type, sorbitan derivative, and aliphatic polyether type; nonionic agents such as Glauber's salt and ammonium sulfate; cationic surfactants such as dodecyltriammonium salts; and anionic surfactants such as sodium dialkyl succinate sulfonate and naphthalene sulfonic acid formalin condensate.

[0052] Furthermore, examples of the fluorescent whitening agent include oxazar derivatives, stilbene derivatives, coumarin derivatives, and naphthalimide derivatives.

[0053] Furthermore, if the fiber surface becomes electrically charged, contact between the aromatic carboxylic acid (A), the isothiazole-based antibacterial agent (B) and / or iodine-based antibacterial agent (C), which are used as needed, and bacteria may be electrically hindered. Therefore, it is preferable to use the antistatic agent as an auxiliary agent. Examples of the antistatic agent include quaternary ammonium salt derivatives and phosphate ester derivatives.

[0054] As already described, the antibacterial treatment solution used in the present invention is obtained by dissolving or dispersing each of the above components in a liquid such as water or an organic solvent, but the order in which the components are added is not particularly limited. Furthermore, it is not necessary to mix all the components in a single solution; a first solution containing the aromatic carboxylic acid (A) and a second solution containing an isothiazole-based antibacterial agent (B) and / or an iodine-based antibacterial agent (C), which may be used as needed, can be prepared and these two solutions mixed to obtain a homogeneous solution or dispersion. In addition, optional components may be added to the single solution, taking their properties into consideration, or, if the solution is divided into two as described above, they can be added to either of the two solutions. Alternatively, a solution containing only optional components may be prepared separately from components (A) to (C), and this solution may be mixed with a solution (one or two solutions) containing components (A) to (C) to finally obtain the antibacterial treatment solution.

[0055] The antibacterial treatment solution is not typically used in its undiluted form, but is diluted to an appropriate ratio before being used to treat fibrous structures. The dilution ratio is generally prepared based on the amount of aromatic carboxylic acid (A), etc., to be contained relative to the dry fiber mass of the fibrous structure to be treated (so-called "%owf").

[0056] Incidentally, as previously stated, the content of the aromatic carboxylic acid (A) in the antibacterial fiber structure of the present invention is set to 0.25 to 10% by mass of the entire antibacterial fiber structure when no other antibacterial agents are present. Furthermore, when other components such as isothiazole-based antibacterial agent (B) and iodine-based antibacterial agent (C) are used, the content is set to 0.1 to 10% by mass of the entire antibacterial fiber structure.

[0057] Next, a method for applying antibacterial treatment to a fibrous structure using the aforementioned antibacterial treatment solution will be described.

[0058] (2) Antimicrobial Treatment Method The antimicrobial treatment method using the antimicrobial treatment solution is important in that the fibrous structure and the antimicrobial treatment solution are in sufficient contact, and the antimicrobial components in the antimicrobial treatment solution [aromatic carboxylic acid (A) + other components (B), (C) as needed] are fixed to the surface and inside of the fibrous material. Two types of such methods can be cited, for example, the atmospheric pressure treatment method and the pressurized treatment method, and the appropriate method can be selected depending on the type and form of the fiber. These treatment methods will be briefly described below.

[0059] (2-1) Atmospheric pressure treatment The atmospheric pressure treatment method is a method of heat treatment using an oven or the like, while the fiber structure is in contact with the antibacterial treatment liquid and impregnated with the antibacterial treatment liquid. To bring the fiber structure into contact with the antibacterial treatment liquid, methods such as spraying or coating the fiber structure with the antibacterial treatment liquid can also be considered, but generally, as schematically shown in Figure 1, it is preferable to fill the immersion tank 1 with the antibacterial treatment liquid 2, immerse the fiber structure 3 in it, and squeeze it with a mangle 4 or the like at a predetermined squeezing ratio, as this makes it easier to control the amount of antibacterial treatment liquid 2 applied to the fiber structure 3. In Figure 1, 5 is a heating device such as an oven. The antibacterial components are then fixed to the fiber structure by the heat treatment.

[0060] The method shown in Figure 1 has essentially the same configuration as methods known in the dyeing field as continuous processing, baking, pad-dry-cure, etc. By using the antibacterial treatment solution instead of (or sometimes together with) the dyeing treatment solution for dyeing processing, antibacterial treatment can be performed.

[0061] Furthermore, the term "atmospheric pressure treatment" refers to performing the treatment without reducing or increasing the pressure, and usually means performing the treatment under atmospheric pressure (1013.25 hPa).

[0062] Furthermore, the heating temperature in the heat treatment (the temperature in the heating space relative to the fiber structure) is usually 100 to 200°C, and the heating time is preferably 10 to 300 seconds. The heating temperature and heating time are adjusted to a suitable range depending on the type of fiber. For example, if the fiber structure is 100% polyester, the heating temperature is preferably 130 to 180°C, and the heating time is preferably 30 to 180 seconds.

[0063] (2-2) Pressurized Treatment Method The pressurized treatment method is a method of fixing antibacterial components to a fiber structure by placing the antibacterial treatment liquid 2 and the fiber structure 3 into a pressure vessel 6, sealing it, and then heating it under pressure, as schematically shown in Figure 2. In particular, it is preferable to perform the treatment in a sealed space such as a pressure vessel 6, as this allows for accurate fixation of volatile aromatic carboxylic acids to the fiber structure 3. The fiber structure 3a on which the antibacterial components have been fixed is dehydrated and dried.

[0064] The method shown in Figure 2 has essentially the same configuration as methods known in the dyeing field as cheese dyeing, batch dyeing, or liquid flow dyeing. By using the antibacterial treatment solution instead of (or sometimes simultaneously with) the dyeing treatment solution for the dyeing process, antibacterial treatment can be performed.

[0065] The degree of pressure applied in the aforementioned "pressure treatment" depends on the type of fiber, but typically refers to treatment under a gauge pressure of approximately 5 to 300 kPa. For example, in the case of polyester fibers, it is preferable to treat them under a gauge pressure of approximately 100 to 300 kPa.

[0066] Furthermore, the heating temperature (temperature inside the pressure vessel) during processing in the pressure vessel is usually preferably 90 to 150°C, and the heating time is preferably 1 to 120 minutes. The heating temperature and heating time are adjusted to a suitable range depending on the type of fiber. For example, if the fiber structure is 100% polyester, the heating temperature is preferably 100 to 135°C, and the heating time is preferably 10 to 100 minutes.

[0067] <Antibacterial Fiber Structure> By processing in this manner, the antibacterial fiber structure of the present invention can be obtained. In the antibacterial fiber structure of the present invention, an aromatic carboxylic acid (A) and, if necessary, other specific components (B) and (C) are impregnated into the fiber as an antibacterial treatment solution, and when heated in that state, the aromatic carboxylic acid (A), etc., enters into the voids between molecules constituting the fiber (amorphous regions loosened by heating), and when cooled, it is strongly fixed into the fiber, thus exhibiting excellent washing durability. For this reason, unlike conventional antibacterial agents attached to the fiber surface by binder processing, the antibacterial properties do not gradually fall off together with the resin binder and rapidly decrease.

[0068] In addition, while binder processing can be used in conjunction with the treatment performed in the present invention, the added resin binder may, conversely, hinder the fixation of the fibers and aromatic carboxylic acid (A), etc. Therefore, when using a resin binder, its use is preferably limited to 5% by mass or less, and more preferably to 1% by mass or less, relative to the entire fiber structure.

[0069] As described above, the antibacterial fiber structure of the present invention obtained in this way has either a predetermined amount of aromatic carboxylic acid (A) fixed in place, or a predetermined amount of aromatic carboxylic acid (A) and small amounts of other components (B) and (C) fixed in place. Therefore, not only is the risk of skin sensitization reduced, but the risks of skin irritation and fiber discoloration, which tend to occur when a high content of a strong antibacterial agent is used, are also suppressed. Thus, it can be provided as a fiber product of excellent quality, not just antibacterial properties. Furthermore, by using an inexpensive aromatic carboxylic acid (A), the amount of expensive antibacterial agents (e.g., isothiazole-based antibacterial agents (B), iodine-based antibacterial agents (C), etc.) used can be reduced, which is also cost-effective.

[0070] Furthermore, since there is no need to coat the fiber surface with a resin binder as in conventional methods, the texture of the fibers does not become stiff, and water absorption is not inhibited.

[0071] Examples of bacteria that can be affected by the antibacterial fiber structure of the present invention include Gram-positive bacteria such as Staphylococcus aureus, MRSA (Methicillin-resistant Staphylococcus aureus), Bacillus subtilis, and Bacillus cereus, as well as Gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, Salmonella typhimurium, and Pseudomonas aeruginosa.

[0072] In this invention, if the antibacterial activity value against Staphylococcus aureus and / or Klebsiella pneumoniae is F or higher, it is evaluated as having "antibacterial properties."

[0073] The aforementioned "antibacterial activity value" can be measured as follows.

[0074] <Method for measuring antibacterial activity> The measurement is performed according to the method compliant with JIS L1902:2015, using "Staphylococcus aureus" and "Klebsiella pneumoniae" as test bacterial species. Specifically, first, each test bacterial species is inoculated into a standard cloth (cotton cloth that does not show antibacterial activity) and an antibacterial treated fiber fabric, and after incubation at 37°C for 18 to 24 hours, the number of viable bacteria in each fabric is measured. The antibacterial activity value is calculated from the measured number of viable bacteria using the calculation shown below.

[0075] Antimicrobial activity value A = (LogCt - LogCo) - (LogTt - LogTo) Growth value F of standard fabric = (LogCt - LogCo) LogCo: Common logarithm of the arithmetic mean of the number of viable bacteria in three samples of standard fabric immediately after inoculation with the test bacteria LogCt: Common logarithm of the arithmetic mean of the number of viable bacteria in three samples of standard fabric after 18 hours of incubation LogTo: Common logarithm of the arithmetic mean of the number of viable bacteria in three samples of treated fiber fabric immediately after inoculation with the test bacteria LogTt: Common logarithm of the arithmetic mean of the number of viable bacteria in three samples of treated fiber fabric after 18 hours of incubation

[0076] Furthermore, if the antibacterial activity value A is F or higher, it is evaluated as "○: Effective," and if A is less than F, it is evaluated as "×: Ineffective" (according to the standards of the Japan Textile Evaluation Technology Council).

[0077] Furthermore, a key feature of the antibacterial fiber structure of the present invention is that its antibacterial properties are durable even after washing. Therefore, the antibacterial properties are evaluated by subjecting the antibacterial fiber structure of the present invention to either "10 washes at 40°C" or "50 washes at 40°C" in accordance with JIS L0217-103, and measuring the antibacterial activity value of the fiber structure after washing.

[0078] Next, embodiments of the present invention will be described together with comparative examples. However, the present invention is not limited to the following embodiments. Unless otherwise specified, all numerical values ​​are expressed on a mass basis.

[0079] [Preparation of Antimicrobial Treatment Solution] First, an antimicrobial treatment solution (hereinafter sometimes referred to as "treatment solution") with the composition shown in Tables 1 and 2 below was prepared by dissolving or suspending an aromatic carboxylic acid (A) and other optional components in water. The components and the fibrous structures (fabrics) to be processed are as follows.

[0080] <Aromatic carboxylic acids (A)> ・BA (benzoic acid, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) <Isothiazole antibacterial agents (B)> ・BIT (Proxel LV, manufactured by Arcsada Corporation) <Iodine-based antibacterial agents (C)> ・IPBC (Polyface P100HP, manufactured by Troy Corporation)

[0081] <Textile Structure> Fiber 1: Fabric made of polyester (100% PET tropical, manufactured by Teijin Corporation) Fiber 2: Fabric made of polyester and cotton (50% PET, 50% cotton, manufactured by Irozome Co., Ltd.)

[0082] Then, using the treatment solution and fiber structure (fabric made of fiber 1 or fiber 2) prepared in this manner, an antibacterial treatment was performed under the conditions shown in Tables 1 and 2 below. After removing the material from the container, it was washed in a washing machine for 5 minutes with overflow water to remove excess components from the fiber surface, and then air-dried overnight to obtain the desired antibacterial fiber structure. The conditions for the antibacterial treatment shown in Tables 1 and 2 are as follows: [Exhaustion] Pressurized treatment method: Processing temperature 130°C, heating time 30 minutes (gauge pressure: 170 kPa) [Atmospheric pressure] Atmospheric pressure treatment method: Processing temperature 180°C, heating time 60 seconds

[0083] Then, the example samples and comparative examples obtained by the antibacterial treatment were evaluated for the following items, following the procedures described for each item.

[0084] <Evaluation of Antibacterial Properties 1 and 2> Each antibacterial fiber structure was subjected to either "10 washes at 40°C" or "50 washes at 40°C" in accordance with JIS L0217-103. After washing, the fiber structures were evaluated for antibacterial properties according to the method in accordance with JIS L1902:2015. For the evaluation of antibacterial property 1, Staphylococcus aureus was used as the test bacterium, and for the evaluation of antibacterial property 2, Klebsiella pneumoniae was used as the test bacterium, and the antibacterial properties were evaluated according to the method described above.

[0085] <Evaluation of Antifungal Properties> Following the method compliant with JIS L1921:2015, "Penicillium citrinum" was used as the test fungal species, and the antifungal activity was evaluated by measuring the amount of ATP contained within the fungal cells. Specifically, first, a liquid culture medium containing spores of the test fungal species was inoculated into the obtained treated product and cultured at 25°C for 42 hours. Then, the amount of ATP after culture was measured, and the antifungal activity value was determined by comparing it with the same test value (ATP amount) of untreated cotton fibers. The calculation of the antifungal activity value was the same as that for the antibacterial activity value, and a value of "2.0" or higher was judged as "○: Effective," and a value less than "2.0" was judged as "×: Ineffective" (according to the standards of the Japan Textile Evaluation Technology Council).

[0086] <Evaluation of Skin Sensitization> Skin sensitization is the process of determining whether the test substance may cause a delayed-type allergic reaction when it comes into contact with the skin. In this disclosure, "○: Meets" indicates that the SEK mark safety standards (safety test methods for processing agents) are met, and "×: Does not meet" indicates that the standards are not met (Standards of the Japan Textile Evaluation Technology Council).

[0087] <Cost Evaluation> The cost of preparing the treatment solution was calculated and compared to the cost of preparing a general treatment solution (a treatment solution used to manufacture general-purpose antibacterial fiber structures). The inexpensive aromatic carboxylic acid was set to 10, and the expensive isothiazole-based antibacterial agents and iodine-based antibacterial agents were set to 100. The cost value was calculated from the content of each and evaluated according to the following criteria: × (poor): Cost value exceeds 2 △ (good): Cost value exceeds 1 and is 2 or less 〇 (very good): Cost value is 1 or less

[0088] <Overall Evaluation> The results of each evaluation (efficacy evaluation: antibacterial activity 1, antibacterial activity 2, antifungal activity) and (essential evaluation: skin sensitization, cost) were evaluated based on the following criteria. × (poor): One of the two essential evaluation items is ×. △ (good): Skin sensitization is ○, cost is △, and there is one or more ○ in the efficacy evaluation. Or, both of the two essential evaluation items are ○, and there is one ○ in the efficacy evaluation. ○ (very good): Both of the two essential evaluation items are ○, and there are two ○ in the efficacy evaluation. ◎ (excellent): Both of the two essential evaluation items are ○, and there are three ○ in the efficacy evaluation.

[0089] [Examples 1-22, Comparative Examples 1-6] By performing antibacterial treatment on fibrous structures under the treatment conditions shown in Tables 1 and 2 below, the desired treated products were obtained. These Examples 1-22 and Comparative Examples 1-6 were then evaluated as described above, and the results are shown in Tables 1 and 2 below.

[0090]

[0091]

[0092] From the results described above, it can be seen that all of Examples 1 to 22 are provided with antibacterial properties that are excellent in terms of wash durability and cost. In particular, Examples 5 to 22, in which a predetermined amount of aromatic carboxylic acid (A), isothiazole antibacterial agent (B), and / or iodine antibacterial agent (C) are used in combination, exhibit excellent antibacterial and antifungal properties due to the synergistic effect of the components, even though each component is contained in a very low concentration relative to the fiber mass, and are found to be antibacterial fiber structures that are gentler on the skin.

[0093] On the other hand, in Comparative Examples 1 and 2, which used only isothiazole antibacterial agent (B) or only iodine-based antibacterial agent (C), the evaluation of skin sensitization was poor, indicating that sufficient antibacterial and antifungal activity was not exhibited. Furthermore, in Comparative Example 3, which used an amount greater than the prescribed amount of iodine-based antibacterial agent (C), antibacterial and antifungal activity was observed, but the evaluation of skin sensitization was poor. In addition, in Comparative Example 4, which used a low concentration of isothiazole antibacterial agent (B) and iodine-based antibacterial agent (C) in combination, and did not use aromatic carboxylic acid (A), the evaluation of skin sensitization was good, but antibacterial and antifungal activity was not observed. Furthermore, in Comparative Example 5, which used less than the prescribed amount of aromatic carboxylic acid (A) as used alone, the evaluation of skin sensitization was good, but antibacterial and antifungal activity was not observed. Finally, in Comparative Example 6, which used aromatic carboxylic acid (A), isothiazole antibacterial agent (B), and iodine-based antibacterial agent (C) in combination, but the amount of aromatic carboxylic acid (A) was insufficient, it also did not exhibit antibacterial and antifungal activity.

[0094] While the above embodiments illustrate specific forms of the present invention, these embodiments are merely illustrative and should not be interpreted restrictively. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0095] This invention is useful in providing an antibacterial fiber structure that exhibits excellent antibacterial properties, suppresses the risk of skin sensitization, and has superior washing durability and cost-effectiveness.

Claims

1. An antibacterial fiber structure in which an aromatic carboxylic acid (A) is fixed to a fiber structure, the fiber structure contains synthetic fibers, and the content of the aromatic carboxylic acid (A) relative to the fiber structure is 0.25 to 10% by mass.

2. An antibacterial fiber structure in which an aromatic carboxylic acid (A) and an isothiazole-based antibacterial agent (B) and / or an iodine-based antibacterial agent (C) are immobilized on a fiber structure, the fiber structure contains synthetic fibers, the content of the aromatic carboxylic acid (A) relative to the fiber structure is 0.1 to 10% by mass, if the isothiazole-based antibacterial agent (B) is immobilized on the fiber structure, the content of the isothiazole-based antibacterial agent (B) relative to the fiber structure is 0.003 to 0.1% by mass, and if the iodine-based antibacterial agent (C) is immobilized on the fiber structure, the content of the iodine-based antibacterial agent (C) relative to the fiber structure is 0.1 to 1% by mass.

3. The antibacterial fiber structure according to claim 1 or 2, wherein the antibacterial activity values ​​(according to JIS L1902:2015) against Staphylococcus aureus and Klebsiella pneumoniae after 10 washes at 40°C (in accordance with JIS L0217-103) are both equal to or greater than the growth value F of the standard fabric.

4. The antibacterial fiber structure according to claim 2 or 3, wherein the isothiazole-based antibacterial agent (B) is a benzoisothiazoline derivative.

5. The antimicrobial fiber structure according to any one of claims 2 to 4, wherein the iodine-based antimicrobial agent (C) is 3-iodo-2-propynyl butylcarbamate.

6. The antibacterial fiber structure according to any one of claims 1 to 5, wherein the aromatic carboxylic acid (A) is benzoic acid.

7. A method for producing an antimicrobial fiber structure according to any one of claims 1 to 6, comprising impregnating a fiber structure containing synthetic fibers with an antimicrobial treatment solution containing the aromatic carboxylic acid (A), and fixing the aromatic carboxylic acid (A) to the fiber structure by heat treatment at 90°C to 200°C.

8. A method for producing an antimicrobial fiber structure according to any one of claims 2 to 6, comprising impregnating a fiber structure containing synthetic fibers with an antimicrobial treatment solution containing the aromatic carboxylic acid (A) and the isothiazole-based antimicrobial agent (B) and / or the iodine-based antimicrobial agent (C), and heat-treating it at 90°C to 200°C to fix the aromatic carboxylic acid (A) and the isothiazole-based antimicrobial agent (B) and / or the iodine-based antimicrobial agent (C) to the fiber structure.

9. The method for producing an antibacterial fiber structure according to claim 7 or 8, wherein the heat treatment is a heat treatment at 100 to 200°C under normal pressure.

10. The method for producing an antibacterial fiber structure according to claim 7 or 8, wherein the heat treatment is a heat treatment at 90 to 150°C under pressure.

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