Antimicrobial fiber and unwoven fabric using same

Abstract

The present invention provides a fiber having excellent antibacterial properties and carding properties at low cost.The fiber is formed from at least one kind of a thermoplastic resin. Polylysine or a salt thereof, and a cationic surfactant are attached to the surface of the fiber. The attached amount of the polylysine or the salt thereof is 0.02-0.06 wt % with respect to the fiber weight, and the attached amount of the cationic surfactant is at least 0.01 wt %.

Description

TECHNICAL FIELD

[0001] The invention relates to a fiber excelling in antibacterial property and carding processability with polylysine or a salt thereof adhered thereto.RELATED ART

[0002] In recent years, in the environment where infectious diseases are prevalent and consumers' awareness of hygiene conditions is increasing, the demand for fibers having antibacterial properties has been increasing. As such fibers, antimicrobial fibers in which polylysine is added, which shows excellent antibacterial properties and high safety, are known. For example, Patent Document 1 discloses an antimicrobial fiber including polylysine or a salt thereof, characterized with extremely low toxicity to the human body, excellent antibacterial properties, and sustained antibacterial properties over a long period. In Patent Document 1, methods are described such as directly mixing polylysine with thermoplastic resin during spinning, or preparing a master batch by adding polylysine and a dispersant to the resin at a high concentration in advance, and then mixing it with raw material pellets during spinning. Also, Patent Document 2 discloses an antimicrobial fiber characterized in that the amount of polylysine or a salt thereof in a fiber made of thermoplastic resin is greater in the outer layer portion than in the inner layer portion of the fiber. It is described that the adhesion of polylysine or the salt thereof can be achieved uniformly and simply by mixing polylysine or the salt thereof with various fiber treatment agents used in a conventional spinning process and drawing process.

[0003] Meanwhile, nonwoven fabrics and fiber products used in an absorbent article or a medical hygiene material are in contact with the skin for a long period, so smooth texture and bulkiness are emphasized. To form such nonwoven fabrics and fiber product, the carding method is most effective as a web formation method compared to the wet method and the spunbond method.PRIOR ART DOCUMENT(S)Patent Document(s)[Patent Document 1] Japanese Patent Application Laid-open No. H10-310935

[0005] [Patent Document 2] Japanese Patent Application Laid-open No. H09-132869SUMMARY OF INVENTIONTechnical Problem

[0006] In the method of Patent Document 1, since polylysine is present not only on the fiber surface but also inside the fiber, the antibacterial effect relative to the addition amount becomes inefficient, and there is an issue that the antibacterial property decreases due to heating during pellet melting. Also, in the method of Patent Document 2, depending on the fiber treatment agent used, there is an issue that the antibacterial property and carding processability may be inhibited. Furthermore, there is an issue that increasing the adhesion amount of polylysine, which is expensive, to enhance antibacterial properties increases the manufacturing cost.

[0007] The invention has been made in view of such issues and aims to provide a fiber excelling in antibacterial property and carding processability at a low cost.Solution to Problem

[0008] The inventors of the invention have conducted extensive research to solve the above issue. As a result, it is found that there are differences in the antibacterial effect of polylysine depending on the ionic properties of the surfactant contained in the fiber treatment agent. It is found that by using a specific adhesion amount of polylysine in combination with a specific adhesion amount of a cationic surfactant, and adhering the polylysine and the surfactant to the fiber surface, a fiber excelling in antibacterial property and carding processability can be obtained at low cost, thus completing the invention.

[0009] That is, the invention has the following configuration.

[0010] [1]A fiber, formed by at least one type of thermoplastic resin, wherein Component A and Component B are adhered to a surface of the fiber, an adhesion amount of Component A is 0.02% by weight to 0.06% by weight with respect to a fiber weight, and an adhesion amount of Component B is 0.01% by weight or more with respect to the fiber weight, Component A is polylysine or a salt thereof, and Component B: a cationic surfactant.

[0011] [2] The fiber according to [1], where the polylysine is ε-polylysine.

[0012] [3] The fiber according to [1] or [2], where Component C is adhered, and Component C is a polyalkylene oxide addition type nonionic surfactant or a polyhydric alcohol type nonionic surfactant.

[0013] [4] The fiber according to [1] or [2], where the cationic surfactant is an alkyl imidazolium alkyl sulfate ester salt as represented in General Formula (1),(wherein R1 is an alkyl group having 7 to 21 carbon atoms, R2 is a methyl group or an ethyl group).[5] The fiber according to any one of [1] to [4], where the fiber is a concentric sheath-core type composite fiber, an eccentric sheath-core type composite fiber, or a side-by-side composite fiber.[6] The fiber according to [5], where at least one thermoplastic resin forming the composite fiber is a polyolefin resin.

[0016] [7]A nonwoven fabric, including the fiber any one of [1] to [6].Effects of Invention

[0017] According to the invention, it is possible to obtain a fiber that has excellent antibacterial property while using an extremely small amount of polylysine, and that excels in carding processability and cost performance.DESCRIPTION OF EMBODIMENTS

[0018] The fiber of the invention is formed by at least one type of thermoplastic resin, and Component A and Component B, which will be described in detail below, are adhered to the surface of the fiber, where the adhesion amount of Component A is 0.02% by weight to 0.06% by weight with respect to the fiber weight, and the adhesion amount of Component B is 0.01% by weight or more with respect to the fiber weight.(Component A)Component A used in the invention is polylysine or a salt thereof. By using Component A, excellent antibacterial property can be imparted to the fiber. Examples of polylysine include α-polylysine or ε-polylysine, with ε-polylysine being preferred due to excellent antibacterial property. ε-polylysine can be manufactured, for example, by fermentation of Streptomyces albulus. Alternatively, commercially available products such as 25% ε-polylysine aqueous solution (manufactured by JNC Corporation) may be used.

[0019] In the invention, free polylysine may be used, or salts with inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, or hydrobromic acid, or salts with organic acids such as acetic acid, citric acid, propionic acid, fumaric acid, or malic acid may be used, or a mixture thereof may be used.

[0020] The adhesion amount of Component A in the invention is 0.02% by weight to 0.06% by weight with respect to the fiber weight, and is preferably 0.02% by weight. to 0.04% by weight. If the adhesion amount of Component A is 0.02% by weight or more, an excellent antibacterial effect can be obtained, and if the adhesion amount of Component A is 0.06% by weight or less, the usage amount of polylysine can be reduced. In addition, there is no risk of contaminating the processing machine, and the fiber can be manufactured at a low cost.(Component B)Component B used in the invention is a cationic surfactant. By using Component B in addition to Component A, a fiber having excellent antibacterial property can be obtained even when the usage amount of Component A is minimized, while imparting carding processability to the fiber. Examples of the cationic surfactant include quaternary ammonium salts such as trimethyltetradecylammonium chloride or octyltrimethylammonium chloride, amine salts such as laurylamine acetate, or alkyl imidazolium alkyl sulfate ester salt, with the alkyl imidazolium alkyl sulfate ester salt being preferred from a safety perspective.

[0021] The alkyl imidazolium alkyl sulfate ester salt used in the invention is not particularly limited, but an alkyl imidazolium alkyl sulfate ester salt represented by General Formula (1) can be exemplified.

[0022] In General Formula (1), R1 is an alkyl group having 7 to 21 carbon atoms, and from the viewpoint of durable hydrophilicity and carding processability, an alkyl group having 15 to 19 carbon atoms is preferred. Also, R2 in General Formula (1) is a methyl group or an ethyl group, and either can be suitably used in the invention. Alkyl imidazolium alkyl sulfate ester salts with a different R1 or R2 may be used in combination.

[0023] The adhesion amount of Component B in the invention is 0.01% by weight or more with respect to the fiber weight, preferably 0.01% by weight to 0.25% by weight, and more preferably 0.03% by weight to 0.14% by weight. If the adhesion amount of Component B is 0.25% by weight or less, the texture becomes favorable as the fiber feels less sticky, and if the adhesion amount of Component B is 0.01% by weight or more, a fiber with excellent carding processability can be obtained.(Component C)The fiber of the invention is not particularly limited, but for the purpose of improving durable hydrophilicity, a polyalkylene oxide addition type nonionic surfactant or a polyhydric alcohol type nonionic surfactant may be adhered as Component C. The polyalkylene oxide addition type nonionic surfactant is not particularly limited, and examples may include polyoxyalkylene alkyl ether, polyoxyalkylene alkyl phenyl ether, polyoxyalkylene fatty acid ester, polyoxyalkylene polyhydric alcohol fatty acid ester, polyoxyalkylene alkyl amino ether, or polyoxyalkylene alkyl alkanolamide. From the viewpoint of improving durable hydrophilicity, polyoxyalkylene alkyl ether or polyoxyalkylene alkyl alkanolamide is perferable. Also, the polyhydric alcohol type nonionic surfactant is not particularly limited, and examples include glycerin fatty acid ester, trimethylolpropane fatty acid ester, pentaerythritol fatty acid ester, sorbitan fatty acid ester, sorbitol fatty acid ester, sucrose fatty acid ester, polyglycerine fatty acid ester. From the viewpoint of improving durable hydrophilicity, glycerin fatty acid ester or polyglycerine fatty acid ester is preferable.

[0024] The adhesion amount of Component C is not particularly limited, but it is preferably 0.005% by weight to 0.6% by weight with respect to the fiber weight, and more preferably 0.02% by weight to 0.5% by weight. If the adhesion amount of Component C is 0.005% by weight or more, the durable hydrophilicity is excellent, and if the adhesion amount of Component C is 0.6% by weight or less, the decrease in initial hydrophilicity can be suppressed.(Component D)The fiber of the invention may have an anionic surfactant adhered as Component D to the extent that the anionic surfactant does not impair the effects of the invention. The anionic surfactant is not particularly limited, and examples include carboxylic acid salt, sulfate ester salt, sulfonic acid salt, or phosphate ester salt.

[0025] The adhesion amount of Component D is not particularly limited, but the adhesion amount of Component D is preferably less than 0.1% by weight, and more preferably Component D is not adhered. Without being bound to a specific theory, the antibacterial property of polylysine is considered to be derived from the electrostatic effect of the protonated amino group in the side chain, and it is considered that increasing the adhesion amount of the anionic surfactant, which easily forms an ion complex and a protonated amino group, tends to inhibit the antibacterial property derived from polylysine.(Other Components)The fiber of the invention may have components other than the above-mentioned Components A to D (other components) adhered thereto. Such other components are not particularly limited, and examples include a pH adjusting agent, a skin protective agent such as squalane or sodium hyaluronate, a hydrophilic agent such as alkyl betaine or polyoxyalkylene modified silicone, a water repellent such as dimethyl polysiloxane (silicone oil) or perfluoroalkyl group-containing compounds, a polyether having a repeating unit such as ethylene oxide (EO) and / or propylene oxide (PO), a block copolymer of polyether and polyester, a polyether adduct of polyhydric alcohol, phenylethyl alcohol, etc., and two or more of the above may be mixed and used. Here, in some cases, ethylene oxide with a repeat number n may be denoted as EO(n), and propylene oxide with a repeat number m may be denoted as PO(m). In addition, an emulsifier, a smoothing agent, a fragrance, a preservative, a rust preventive, a defoaming agent, etc., may be added.(Fiber)The fiber of the invention is formed by at least one thermoplastic resin, and may be a fiber formed by a single thermoplastic resin (single fiber) or a composite fiber formed by two or more types of thermoplastic resins. The thermoplastic resin forming the fiber of the invention is not particularly limited, and examples include polyolefin resin, polyester resin, acrylic resin, nylon resin, or polyvinyl chloride resin, but from the viewpoint of imparting excellent texture to nonwoven fabrics and fiber products, it is preferably a polyolefin resin. The polyolefin resin is not particularly limited, and examples include a polyethylene resin such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE), or a polypropylene resin such as crystalline polypropylene (PP), or a copolymer of propylene as the main component with ethylene or α-olefin (Co-PP).In the case where the fiber of the invention is a composite fiber, the composite form is not particularly limited, and examples include a concentric sheath-core type composite fiber, an eccentric sheath-core type composite fiber, a side-by-side composite fiber, a radial type composite fiber, or a sea-island type composite fiber. However, from the viewpoint of texture and strength, a concentric sheath-core type composite fiber, an eccentric sheath-core type composite fiber, or a side-by-side composite fiber is preferred. The thermoplastic resin forming the composite fiber is not particularly limited, but from the viewpoint of imparting excellent texture to nonwoven fabrics and fiber products, it is preferable that at least one of the thermoplastic resins is a polyolefin resin. The combination of the thermoplastic resin forming the composite fiber is not particularly limited, but it is preferable that the melting point difference is 10° C. or more, and more preferably 20° C. or more. By having a melting point difference, thermal adhesiveness can be imparted to the composite fiber, and since nonwoven fabrics can be formed without using components that have some irritation to the skin such as adhesives, it is possible to reduce skin irritation. Specific combinations of high melting point component / low melting point component include PP / HDPE, PP / Co-PP, polyethylene terephthalate (PET) / HDPE, PET / LLDPE, PET / copolymerized polyethylene terephthalate (Co-PET), PET / PP, or polylactic acid (PLA) / HDPE, but from the viewpoint of texture, raw material cost, production stability, etc., the combination of PP / HDPE or PET / HDPE is preferred. Also, from the viewpoint of thermal adhesiveness of the composite fiber, it is preferable that the low melting point component occupies 50% or more of the area of the surface of the composite fiber, and more preferably 70% or more of the area.

[0027] Also, the volume ratio of the high melting point component and the low melting point component not particularly limited, but when the ratio of the high melting point component is large, there is a tendency for the texture of nonwoven fabrics and fiber products to improve, and when the ratio of the low melting point component is large, there is a tendency for the adhesion point strength between composite fibers to improve, resulting in nonwoven fabrics with high strength. From such viewpoint, the volume ratio of the high melting point component and the low melting point component is preferably 20 / 80 to 80 / 20, and more preferably 30 / 70 to 70 / 30.

[0028] The cross-sectional shape of the fiber is not particularly limited, and any of round shapes such as circle or oval, angular shapes such as triangle or square, modified shapes such as star or eight-leaf shape, or divided or hollow shapes can be used. Also, an additive such as an antioxidant, a light stabilizer, a ultraviolet absorber, a neutralizing agent, a nucleating agent, an epoxy stabilizer, a lubricant, a flame retardant, an antistatic agent, a pigment, or a plasticizer may be included as needed to the extent that the effects of the invention are not affected.

[0029] The fineness of the fiber is not particularly limited, and 0.6 dtex to 5.0 dtex can be exemplified. Specifically, in the case of using the fiber as a surface material for an absorbent article such as disposable diapers, by making the fiber fineness low, the texture of nonwoven fabrics and fiber products becomes favorable. Furthermore, since the texture becomes smoother when the fineness is low, the friction with the skin is reduced, and rashes and the like can be suppressed. On the other hand, from the viewpoint of processability, handling properties, production cost, etc., it is preferable to have a certain degree of fineness. From the viewpoint, the fineness of the fiber is more preferably 1.3 dtex to 2.6 dtex.(Nonwoven Fabric)The nonwoven fabric of the invention includes the fiber described above, and therefore possesses excellent antibacterial property, has a bulky and smooth texture, and can be obtained at a low cost.

[0030] The nonwoven fabric of the invention may include fibers other than the fiber of the invention as needed to the extent that such fibers do not interfere with the effects of the invention, and the proportion thereof is not particularly limited, but can be 1% by weight to 30% by weight with respect to the weight of the nonwoven fabric. If the proportion of fibers other than the fiber of the invention is 1% by weight or more, effects commensurate with use can be obtained, and if it is 30% by weight or less, a satisfactory antibacterial property can be obtained, and issues occurring in the carding process such as poor fiber dispersion and discharge properties can be reduced. At this time, it is preferable that the adhesion amount of Component A in the entire nonwoven fabric is 0.02% by weight or more, and the adhesion amount of Component B is 0.01% by weight or more. Specifically, in the case of mixing 70% by weight of fibers to which Component A is adhered at 0.06% by weight and Component B is adhered at 0.05% by weight with respect to the fiber weight, and 30% by weight of fibers to which neither Component A nor Component B is adhered, since Component A becomes 0.02% by weight or more of the entire nonwoven fabric, the nonwoven fabric excels in antibacterial property. Also, since Component B becomes 0.010% by weight or more of the entire nonwoven fabric, issues in the carding process can be reduced. As fibers other than the fiber of the invention, natural fibers (such as cotton), regenerated fibers (such as rayon), semi-synthetic fibers (such as acetate), synthetic fibers (polyester, polyolefin, acrylic, or nylon), or composite fibers can be exemplified, where the adhesion amounts of Component A and Component B are outside the ranges described above.

[0031] The nonwoven fabric of the invention may be a single type (single layer) of nonwoven fabric, or may be a laminate of two or more types of nonwoven fabrics having different fineness, components, densities, etc. In the case of a laminate of two or more types of nonwoven fabrics, for example, by laminating nonwoven fabrics formed from fibers with different fineness or components, it can be made into a nonwoven fabric in which the size of the gaps formed between fibers and the degree of hydrophilicity change, and texture, hydrophilicity, etc., can be controlled.

[0032] The nonwoven fabric of the invention may be, though not particularly limited, a laminate with a sheet that does not include the fiber of the invention (a sheet other than the nonwoven fabric of the invention). As a sheet that does not include the fiber of the invention, webs, through-air nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, needlepunch nonwoven fabrics, films, meshes, nets, or woven or knitted fabrics can be exemplified. By laminating with such sheet, various physical properties such as texture, durable hydrophilicity, and strength can be controlled. As a method for obtaining such a laminate, a method of laminating a web including the fiber of the invention and a web not including the fiber of the invention, and integrating the webs by lamination by the through-air method, etc., or a method of separately preparing the nonwoven fabric of the invention and a sheet not including the fibers of the invention, and integrating the nonwoven fabric and the sheet by lamination through an adhesive or a calendering process can be exemplified.

[0033] The nonwoven fabric of the invention may be subjected to antistatic treatment, water repellent treatment, hydrophilic treatment, antibacterial treatment, ultraviolet absorption treatment, near-infrared absorption treatment, or electret treatment, etc., according to the purpose, to the extent that the effects of the invention are not affected.

[0034] The weight per unit area of the nonwoven fabric is not particularly limited, but can be 8 g / m2 to 40 g / m2, and more preferably 10 g / m2 to 30 g / m2.

[0035] The thickness of the nonwoven fabric is not particularly limited, but can be 0.2 mm to 4.0 mm, and more preferably 0.4 mm to 2.0 mm.

[0036] The antibacterial activity value of the nonwoven fabric is not particularly limited, but it is preferable that the antibacterial activity value is 2 or more, and more preferably 4 or more. The evaluation method for the antibacterial activity value will be described in the examples.

[0037] The nonwoven fabric of the invention is not particularly limited and can be suitably used in various fiber products requiring antibacterial properties, such as absorbent articles including diapers, sanitary napkins, or incontinence pads; hygiene materials including masks, gowns, or surgical gowns; interior materials including wall sheets, shoji paper, or flooring materials; daily life materials including cover cloths, cleaning wipers, or food waste covers; toiletry products including disposable toilets or toilet covers; pet supplies including pet sheets, pet diapers, or pet towels; industrial materials including wiping materials, filters, cushioning materials, oil absorbents, or absorbents for ink tanks; general medical materials, bedding materials, nursing care products, etc. In particular, it is suitable for the surface material of absorbent articles where smoothness of texture is emphasized, such as diapers, sanitary napkins, or incontinence pads.(Method for Manufacturing Fibers)The method for manufacturing the fiber of the invention is not particularly limited. However, examples include a method of applying a fiber treatment agent in which Component A and Component B are mixed to the fiber, and a method of applying (top coating) Component A over Component B that has been applied to the fiber. The application method is not particularly limited, and after the spinning process of the fiber, after the drawing process, or after the drying process, the components can be applied by conventional processes such as contact with an oiling roll, immersion to an immersion bath, or spray application. Among the above, it is preferable to adopt a method in which a fiber treatment agent in which Component A and Component B are mixed is applied to the fiber through contact with an oiling roll after the spinning process or after the drawing process, because Component A and Component B can be uniformly applied, making the effects of the invention more pronounced.(Method for Manufacturing Nonwoven Fabric)The manufacturing method of the nonwoven fabric of the invention is not particularly limited, but examples include a method of preparing a web containing the fiber of the invention as described above by the carding method, and integrating the web by the through-air method, the spunlace method, or the needle punch method. The nonwoven fabric of the invention has the properties of smooth texture and bulkiness because the web is prepared by the carding method. The method for integrating the web is preferably the through-air method, which results in a smooth texture. In the invention, “web” refers to a fiber aggregate in which fibers are loosely entangled to the extent of being able to maintain a sheet-like state, meaning a state in which the fibers are not adhered to each other or a state in which the fibers are not firmly entangled with each other.EXAMPLESThe invention will be described in detail by the following examples, but the invention is not limited by the examples. The measurement methods or definitions of the physical property values shown in the examples are described below.<Fiber Treatment Agent>

[0039] The compositions of fiber treatment agents (1) to (12) applied to the fibers of the invention are shown in Table 1. The numerical values of the respective components in Table 1 indicate weight % in the fiber treatment agents.TABLE 1Fiber treatment agentComponent (%)(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)AA14.77.510.730.82.26.211.54.92.3BB19.59.38.910.09.9B269.2100.0CC126.725.925.028.027.3C24.84.64.55.04.9C395.1100.0C424.423.422.1C514.914.313.5DD19.59.28.6D229.928.526.9OthersOther 126.725.925.028.027.3Other 219.118.517.920.019.5Other 38.58.38.09.08.8Other 419.118.417.4

[0040] The components of the fiber treatment agents in Table 1 are indicated by the following abbreviations.

[0041] A1: ε-polylysine

[0042] B1: 1-(2-hydroxyethyl)-1-ethyl-2-pentadecyl-2-imidazolium ethyl sulfate ester salt

[0043] B2: Trimethyltetradecylammonium chloride

[0044] C1: Hexaglycerine monostearic acid ester

[0045] C2: Stearic acid amide EO(20) adduct

[0046] C3: Polyoxyethylene alkyl ether (C=12 to 15)

[0047] C4: Castor oil oleic acid adduct

[0048] C5: (Mono, di) glyceride of fatty acids with carbon numbers 14-18 (however, fatty acids with carbon number 18 are unsaturated fatty acids)

[0049] D1: Sodium di-2-ethylhexyl sulfosuccinate

[0050] D2: Dioctyl sulfosuccinate sodium salt

[0051] Other 1: Polyether compound (EO(20)⋅PO(10))

[0052] Other 2: Block copolymer of polyether with (—C2H4O—) as a repeating unit and polyester with (—C5H10COO—) as a repeating unit

[0053] Other 3: Polyoxyalkylene modified silicone

[0054] Other 4: Trimethylolpropane PO⋅EO copolymer adduct<Fiber Fineness>The fiber fineness was measured in accordance with JIS L 1015.<Adhesion Amount of Fiber Treatment Agent>Measurement was performed by using 2 g of fibers formed into a web by a roller card tester, using a rapid residual oil extraction device of OC-1 type manufactured by Intech Co., Ltd. 25 ml of methanol was used as the extraction solvent. The liquid dripping from a hole at the bottom was received in a heated aluminum dish, and the methanol was evaporated. The weight (g) of the residue in the aluminum dish was measured, and the adhesion amount was calculated according to the following formula.Adhesion⁢ amount(weight⁢ %)=(Weight⁢ of⁢ ⁢residue(g) / 2⁢(g))×100<Adhesion Amounts of Component A, Component B, Component C, Component D, and Other Components>The adhesion amount of each component was calculated from the adhesion amount of the fiber treatment agent and the composition ratio in Table 1.<Antibacterial Property Test>The antibacterial property test was conducted in accordance with the bacteria emulsion absorption method in JIS L1902:2015. The test bacterial emulsion was uniformly inoculated onto a nonwoven fabric sterilized by UV irradiation, and a sterilized cap was tightened. The product was cultured for 18 hours at 37±1° C., and the number of viable bacteria after cultivation was measured. Two types of samples were used: standard cotton fabric and nonwoven fabric prepared in each example. Escherichia coli (Escherichia coli NBRC3301) and Staphylococcus aureus (Staphylococcus aureus NBRC12732) were used as test bacteria. Then, the antibacterial activity value, which is an indicator of antibacterial property, was calculated according to the following formula.Antibacterial⁢ activity⁢ value=(log⁢Ct-log⁢C0)-(log⁢Tt-log⁢T0)Here, logC0: the average of the number of bacteria recovered immediately after inoculation on the standard fabric, logCt: the average of the number of bacteria recovered after 18 hours of cultivation on the standard fabric, logT0: the average of the number of bacteria recovered immediately after inoculation on the treated fabric, logTt: the average of the number of bacteria recovered after 18 hours of cultivation on the treated fabric.The antibacterial property was evaluated based on the following criteria.⊚: The smaller of the antibacterial activity values against Escherichia coli and Staphylococcus aureus is 4 or higher.◯: The smaller of the antibacterial activity values against Escherichia coli and Staphylococcus aureus is 2 or higher and less than 4.x: The smaller of the antibacterial activity values against Escherichia coli and Staphylococcus aureus is less than 2.<Carding Processability>When passing fibers through a roller carding machine, phenomena such as weak entanglement of raw cotton causing the cotton to float up (fly), web not being discharged from the roll due to static electricity, and formation of fiber clumps (nep) in the web were visually recognized, and the carding processability was evaluated according to the following criteria.◯: No phenomena of poor carding processability due to fly, nep, or static electricity occurs even after 8 hours or more of operation.x: Phenomena of poor carding processability due to fly, nep, or static electricity occur within 8 hours from the start of operation.Example 1A concentric sheath-core type composite fiber with high-density polyethylene on the sheath side and polyethylene terephthalate on the core side was melt-spun at a volume ratio of 50 / 50. After going through the drawing process, an aqueous solution of fiber treatment agent (1) diluted with ion-exchanged water was brought into contact with an oiling roll so that the adhesion amount of fiber treatment agent (1) was about 0.5% by weight relative to the fiber weight, and was applied to the fiber surface. Subsequently, fibers were obtained by being imparted with crimps and dried, and then cut to a fiber length of 51 mm.Subsequently, the fibers were processed into a card web using a roller carding machine, and the web was processed at 130° C. with a suction dryer to obtain a nonwoven fabric.Example 2A concentric sheath-core type composite fiber with high-density polyethylene on the sheath side and polypropylene on the core side was melt-spun at a volume ratio of 50 / 50. After going through the drawing process, crimps were imparted, and an aqueous solution of fiber treatment agent (1) diluted with ion-exchanged water was sprayed, so that the adhesion amount of fiber treatment agent (1) was about 0.5% by weight relative to the fiber weight, thereby being applied to the fiber surface. Subsequently, the fibers were obtained by being dried and cut to a fiber length of 51 mm. Then, a nonwoven fabric was obtained in the same manner as in Example 1.Examples 3 to 5, Comparative Examples 1 to 8Fibers and nonwoven fabrics were obtained in the same manner as in Example 1 except that the fiber treatment agent was changed as shown in Table 2.The results of fiber fineness, adhesion amount of each component, antibacterial property, and carding processability obtained in Examples 1-5 and Comparative Examples 1-8 are shown in Tables 2 and 3.TABLE 2Example 1Example 2Example 3Example 4Example 5ResinPE / PETPE / PPPE / PETPE / PETPE / PET(50 / 50)(50 / 50)(50 / 50)(50 / 50)(50 / 50)Fiber fitness (dtex)2.6 2.2 1.3 1.7 2.6 FiberType(1)  (1)  (2)  (3)  (4)  treatmentAdhesion amount (%)0.430.440.5 0.550.07agentBreakdownComponent A0.020.020.040.060.02(%)Component B0.040.040.050.050.05Component C0.140.140.150.16—Component D—————Other0.230.240.260.28—componentsAntibacterialAntibacterialEscherichia coli4.7 2.3 6  5  4.2 propertyactivity valueStaphylococcus4.2 2.7 5.7 5.4 4  Evaluation⊚◯⊚⊚⊚Carding processability◯◯◯◯◯TABLE 3Compar-Compar-Compar-Compar-Compar-Compar-Compar-Compar-ativeativeativeativeativeativeativeativeExam-Exam-Exam-Exam-Exam-Exam-Exam-Exam-ple 1ple 2ple 3ple 4ple 5ple 6ple 7ple 8ResinPE / PETPE / PETPE / PETPE / PETPE / PETPE / PETPE / PETPE / PET(50 / 50)(50 / 50)(50 / 50)(50 / 50)(50 / 50)(50 / 50)(50 / 50)(50 / 50)Fiber fitness (dtex)2.62.62.62.62.6 2.62.62.6 FiberType(5)  (6)  (7)  (8)  (9)  (10)  (11)  (12)   treatmentAdhesion amount (%) 0.51 0.53 0.560.40.51 0.48 0.060.5 agentBreakdownComponent A 0.01 0.03 0.06—0.02——0.01(%)Component B——— 0.04—— 0.060.05Component C0.20.20.2 0.130.49 0.48—0.16Component D0.10.10.1—————Other0.20.20.2 0.23———0.28componentsAntibacterialAntibacterialEscherichia coli0.20.11.60.46.3 2.80.50.2 propertyactivityStaphylococcus−0.8 −0.1 1.11.85  0.81.90.7 valueaureusEvaluationXXXX⊚XXXCarding processability◯◯◯◯XX◯◯From the results in Table 2, compared to Examples 1, 3, and 4, Comparative Example 4 did not contain Component A, and Comparative Example 8 had low antibacterial property because the adhesion amount of Component A was smaller at 0.01% by weight. From this, it can be seen that when 0.02% by weight or more of Component A relative to the fiber weight was adhered, an excellent antibacterial property was exhibited. In addition, Comparative Example 5, which did not have Component B adhered, showed poor carding processability. Furthermore, Comparative Example 6, which had neither Component A nor Component B adhered, showed poor results in both antibacterial property and carding processability.From this, it is necessary that both Component A and Component B are adhered in predetermined amounts in order to exhibit excellent antibacterial property and carding processability.In addition, Comparative Examples 1-3, which had a large amount of Component D adhered, showed low antibacterial property. This may be because the antibacterial effect of polylysine was inhibited by Component D.In addition, from the comparison between Example 1 and Example 2, even with equivalent adhesion components onto the fiber, there is a difference in antibacterial property depending on the adhesion method, and it is considered that, with the method of Example 1, high antibacterial effect was obtained because the uniformity of adhesion was improved.INDUSTRIAL APPLICABILITYThe antimicrobial fiber of the invention has excellent antibacterial property and carding processability, and can be obtained at low cost, therefore it can be suitably used in various fiber products requiring antibacterial property and smooth texture, such as absorbent articles including diapers, sanitary napkins, or incontinence pads; hygiene materials including masks, gowns, or surgical gowns; interior materials including wall sheets, shoji paper, or flooring materials; daily life materials including cover cloths, cleaning wipers, or food waste covers; toiletry products including disposable toilets or toilet covers; pet supplies including pet sheets, pet diapers, or pet towels; industrial materials including wiping materials, filters, cushioning materials, oil absorbents, or absorbents for ink tanks; general medical materials, bedding materials, nursing care products, etc.

Claims

1. A fiber, formed by at least one type of thermoplastic resin, wherein Component A and Component B are adhered to a surface of the fiber, an adhesion amount of Component A is 0.02% by weight to 0.06% by weight with respect to a fiber weight, and an adhesion amount of Component B is 0.01% by weight or more with respect to the fiber weight,Component A is polylysine or a salt thereof, andComponent B: a cationic surfactant.

2. The fiber as claimed in claim 1, wherein the polylysine is ε-polylysine.

3. The fiber as claimed in claim 1, wherein Component C is adhered, andComponent C is a polyalkylene oxide addition type nonionic surfactant or a polyhydric alcohol type nonionic surfactant.

4. The fiber as claimed in claim 1, wherein the cationic surfactant is an alkyl imidazolium alkyl sulfate ester salt as represented in General Formula (1),wherein R1 is an alkyl group having 7 to 21 carbon atoms, R2 is a methyl group or an ethyl group.

5. The fiber as claimed in claim 1, wherein the fiber is a concentric sheath-core type composite fiber, an eccentric sheath-core type composite fiber, or a side-by-side composite fiber.

6. The fiber as claimed in claim 5, wherein at least one thermoplastic resin forming the composite fiber is a polyolefin resin.

7. A nonwoven fabric, comprising the fiber as claimed in claim 1.

8. The fiber as claimed in claim 2, wherein Component C is adhered, andComponent C is a polyalkylene oxide addition type nonionic surfactant or a polyhydric alcohol type nonionic surfactant.

9. The fiber as claimed in claim 2, wherein the cationic surfactant is an alkyl imidazolium alkyl sulfate ester salt as represented in General Formula (1),wherein R1 is an alkyl group having 7 to 21 carbon atoms, R2 is a methyl group or an ethyl group.

10. The fiber as claimed in claim 2, wherein the fiber is a concentric sheath-core type composite fiber, an eccentric sheath-core type composite fiber, or a side-by-side composite fiber.

11. A nonwoven fabric, comprising the fiber as claimed in claim 2.

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