Antibacterial fibers and nonwoven fabrics using the same

Abstract

To provide a fiber having excellent antibacterial properties and carding properties at low cost.SOLUTION: A fiber is formed from at least one thermoplastic resin. Polylysine or a salt thereof, and a cationic surfactant are attached to the surface of the fiber. The amount of the polylysine or the salt thereof attached on the fiber is 0.02-0.06 wt.% with respect to the fiber weight, and the amount of the attached cationic surfactant is at least 0.01 wt.%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a fiber having excellent antibacterial properties and carding processability, to which polylysine or a salt thereof is attached. [Background technology]

[0002] In recent years, with the rise of infectious disease outbreaks and increased consumer awareness of hygiene, the demand for antibacterial fibers has been growing. Among such fibers, antibacterial fibers containing polylysine, which exhibits excellent antibacterial properties and high safety, are known. For example, Patent Document 1 discloses an antibacterial fiber containing polylysine or a salt thereof, characterized by extremely low toxicity to the human body, excellent antibacterial properties, and long-lasting antibacterial activity. Patent Document 1 describes a method of directly mixing polylysine with a thermoplastic resin during spinning, and a method of preparing a masterbatch by pre-adding polylysine and a dispersant to the resin at a high concentration and mixing it with the raw material pellets during spinning. Furthermore, Patent Document 2 discloses an antibacterial fiber made of a thermoplastic resin, characterized in that the amount of polylysine or a salt thereof is greater in the outer layer of the fiber than in the inner layer. It is stated that polylysine or a salt thereof can be uniformly and easily attached by mixing it with various fiber treatment agents used in the spinning and drawing processes.

[0003] On the other hand, nonwoven fabrics and textile products used in absorbent materials and medical and sanitary materials are in contact with the skin for extended periods, so a smooth texture and bulkiness are important. To form such nonwoven fabrics and textile products, the carding method is the most effective web formation method compared to the wet method and the spunbond method. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-310935 [Patent Document 2] Japanese Patent Application Publication No. 9-132869 [Overview of the project] [Problems that the invention aims to solve]

[0005] The method described in Patent Document 1 has the problem that, because polylysine is present not only on the fiber surface but also inside the fiber, the antibacterial effect is inefficient in relation to the amount added, and the antibacterial properties decrease due to heating during pellet melting. Furthermore, the method described in Patent Document 2 has the problem that antibacterial properties and carding properties are inhibited depending on the fiber treatment agent used. In addition, increasing the amount of expensive polylysine attached to enhance antibacterial properties increases manufacturing costs.

[0006] This invention was made in view of these circumstances, and aims to provide a fiber with excellent antibacterial properties and carding properties at a low cost. [Means for solving the problem]

[0007] The inventors diligently conducted research to solve the above problems. As a result, they discovered that the antibacterial effect of polylysine differs depending on the ionicity of the surfactant contained in the fiber treatment agent. They then found that by using a specific amount of polylysine and a specific amount of cationic surfactant in combination and attaching them to the fiber surface, it is possible to obtain fibers with excellent antibacterial properties and carding properties at low cost, thus completing the present invention.

[0008] In other words, the present invention has the following configuration. [1] A fiber composed of at least one thermoplastic resin, wherein the surface of the fiber has the following components A and B attached to it, the amount of component A attached is 0.02 to 0.06% by weight relative to the fiber weight, and the amount of component B attached is 0.01% by weight or more relative to the fiber weight. Component A: Polylysine or its salt Ingredient B: Cationic surfactant [2] The fiber according to [1], wherein the polylysine is ε-polylysine. [3] The fibers described in [1] or [2] to which component C below is attached. Component C: Polyalkylene oxide-added nonionic surfactant or polyhydric alcohol-type nonionic surfactant [4] The fiber according to any one of [1] to [3], wherein the cationic surfactant is an alkylimidazolium alkyl sulfate salt represented by general formula (1). TIFF0007897172000001.tif56152 (in the formula, R 1 R is an alkyl group having 7 to 21 carbon atoms. 2 (This refers to a methyl group or an ethyl group.) [5] The fiber according to any one of [1] to [4], wherein the fiber is a concentric sheath core type composite fiber, an eccentric sheath core type composite fiber, or a parallel type composite fiber. [6] The fiber according to [5], wherein at least one thermoplastic resin constituting the composite fiber is a polyolefin resin. Nonwoven fabric containing any of the fibers described in [7][1] to [6]. [Effects of the Invention]

[0009] According to the present invention, it is possible to obtain a fiber that has excellent antibacterial properties while also having excellent carding properties and cost-effectiveness by using a very small amount of polylysine. [Modes for carrying out the invention]

[0010] The fiber of the present invention is composed of at least one thermoplastic resin, and components A and B, as detailed below, are attached to the surface of the fiber, characterized in that the amount of component A attached is 0.02 to 0.06% by weight relative to the fiber weight, and the amount of component B attached is 0.01% by weight or more relative to the fiber weight.

[0011] (Component A) Component A used in the present invention is polylysine or its salt. By using Component A, excellent antibacterial properties can be imparted to the fiber. Examples of polylysine include α-polylysine or ε-polylysine, and ε-polylysine, which is excellent in antibacterial properties, is preferred. ε-Polylysine can be produced, for example, by fermentation of Streptomyces albulus. Also, commercially available products such as a 25% aqueous solution of ε-polylysine (manufactured by JNC Corporation) may be used.

[0012] In the present 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 mixtures of these may be used.

[0013] The adhesion amount of Component A in the present invention is 0.02 to 0.06% by weight based on the fiber weight, and preferably 0.02 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. If it is 0.06% by weight or less, the amount of polylysine used can be reduced, and there is no risk of contaminating the processing machine, and the fiber can be produced at low cost.

[0014] (Component B) Component B used in the present invention is a cationic surfactant. By using Component B in combination with Component A, while imparting card processing properties to the fiber, fibers having excellent antibacterial properties can be obtained even when the amount of Component A used is extremely small. Examples of the cationic surfactant include quaternary ammonium salts such as trimethyltetradecylammonium chloride or octyltrimethylammonium chloride, amine salts such as laurylamine acetate, or alkylimidazolium alkyl sulfate salts. From the viewpoint of safety, an alkylimidazolium alkyl sulfate salt is preferred.

[0015] The alkylimidazolium alkyl sulfate salt used in the present invention is not particularly limited, and examples thereof include alkylimidazolium alkyl sulfate salts represented by the general formula (1). TIFF0007897172000002.tif56152

[0016] R in the general formula (1) 1 is an alkyl group having 7 to 21 carbon atoms, and from the viewpoints of durable hydrophilicity and card processing properties, it is preferably an alkyl group having 15 to 19 carbon atoms. Also, R in the general formula (1) 2 is a methyl group or an ethyl group, and either can be preferably used in the present invention. The alkylimidazolium alkyl sulfate salt may be used in combination with those having different R 1 or R 2 .

[0017] The adhesion amount of component B in the present invention is 0.01% by weight or more based on the fiber weight, preferably 0.01 to 0.25% by weight, and more preferably 0.03 to 0.14% by weight. If the adhesion amount of component B is 0.25% by weight or less, the fiber will feel less sticky and the texture will be good. If it is 0.01% by weight or more, fibers with excellent card processing properties can be obtained.

[0018] (Component C) The fibers of the present invention are not particularly limited, but for the purpose of improving durable hydrophilicity, a polyalkylene oxide-added nonionic surfactant or a polyhydric alcohol-type nonionic surfactant may be attached as component C. The polyalkylene oxide-added nonionic surfactant is not particularly limited, and examples include polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene fatty acid esters, polyoxyalkylene polyhydric alcohol fatty acid esters, polyoxyalkylene alkylamino ethers, or polyoxyalkylene alkyl alkanolamides. From the viewpoint of improving durable hydrophilicity, polyoxyalkylene alkyl ethers or polyoxyalkylene alkyl alkanolamides are preferred. The polyhydric alcohol-type nonionic surfactant is not particularly limited, and examples include glycerin fatty acid esters, trimethylolpropane fatty acid esters, pentaerythritol fatty acid esters, sorbitan fatty acid esters, sorbitol fatty acid esters, sucrose fatty acid esters, and polyglycerin fatty acid esters. From the viewpoint of improving durable hydrophilicity, glycerin fatty acid esters or polyglycerin fatty acid esters are preferred.

[0019] The amount of component C attached is not particularly limited, but is preferably 0.005 to 0.6% by weight relative to the fiber weight, and more preferably 0.02 to 0.5% by weight. If it is 0.005% by weight or more, it exhibits excellent durability hydrophilicity, and if it is 0.6% by weight or less, it can suppress the decrease in initial hydrophilicity.

[0020] (Component D) The fibers of the present invention may have an anionic surfactant attached as component D, to the extent that it does not impair the effects of the present invention. The anionic surfactant is not particularly limited, and examples include carboxylates, sulfates, sulfons, or phosphates.

[0021] The amount of component D attached is not particularly limited, but is preferably less than 0.1% by weight, and more preferably no component D is attached. Although not bound by any particular theory, the antibacterial properties of polylysine are thought to originate from the electrostatic effect of the protonated amino group of the side chain, and it is thought that increasing the amount of anionic surfactant that readily forms an ionic complex with the protonated amino group tends to inhibit the antibacterial properties derived from polylysine.

[0022] (Other ingredients) The fibers of the present invention may have components other than those described above (other components) attached to them. These other components are not particularly limited and may include pH adjusters, skin protectants such as squalane or sodium hyaluronate, hydrophilic agents such as alkyl betaine or polyoxyalkylene-modified silicone, water repellents such as dimethylpolysiloxane (silicone oil) or perfluoroalkyl group-containing compounds, polyethers with repeating units of ethylene oxide (EO) and / or propylene oxide (PO), block copolymers of polyethers and polyesters, polyether adducts of polyhydric alcohols, phenylethyl alcohol, etc. Two or more of these may also be used in mixture. Here, when the number of repeating units of ethylene oxide is n, it may be denoted as EO(n), and when the number of repeating units of propylene oxide is m, it may be denoted as PO(m). In addition, emulsifiers, smoothing agents, fragrances, preservatives, rust inhibitors, defoaming agents, etc. may be added.

[0023] (fiber) The fibers of the present invention are composed of at least one type of thermoplastic resin, and may be fibers composed of a single thermoplastic resin (single fiber) or composite fibers composed of two or more types of thermoplastic resins. The thermoplastic resin constituting the fibers of the present invention is not particularly limited, and examples include polyolefin resins, polyester resins, acrylic resins, nylon resins, or vinyl chloride resins, but polyolefin resins are preferred from the viewpoint of imparting excellent texture to nonwoven fabrics and textile products. Examples of polyolefin resins are not particularly limited, and examples include polyethylene resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE), or polypropylene resins such as crystalline polypropylene (PP), or copolymers of propylene and ethylene or α-olefin (Co-PP) with propylene as the main component.

[0024] When the fiber of the present invention is a composite fiber, the composite form is not particularly limited, and examples include concentric sheath-core composite fibers, eccentric sheath-core composite fibers, parallel composite fibers, radial composite fibers, or sea-island composite fibers. However, from the viewpoint of texture and strength, concentric sheath-core composite fibers, eccentric sheath-core composite fibers, or parallel composite fibers are preferred. Furthermore, the thermoplastic resin constituting the composite fiber is not particularly limited, but from the viewpoint of imparting excellent texture to nonwoven fabrics and textile products, it is preferable that at least one of the thermoplastic resins is a polyolefin resin. Furthermore, the combination of thermoplastic resins constituting 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. Having a melting point difference allows for heat adhesion to the composite fiber, and since nonwoven fabrics can be made without using components that have some degree of skin irritation, such as adhesives, it is possible to reduce skin irritation. Specific examples of high-melting-point / low-melting-point component combinations 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. However, from the viewpoint of texture, raw material cost, and production stability, the PP / HDPE or PET / HDPE combination is preferred. Furthermore, from the viewpoint of the heat adhesion of the composite fiber, it is preferable that the low-melting-point component occupies 50% or more of the surface area of ​​the composite fiber, and more preferably 70% or more.

[0025] Furthermore, while there are no particular limitations on the volume ratio of high-melting-point components to low-melting-point components, a higher proportion of high-melting-point components tends to improve the texture of nonwoven fabrics and textile products, and a higher proportion of low-melting-point components tends to improve the bonding strength between composite fibers, resulting in a nonwoven fabric with higher strength. From this viewpoint, the volume ratio of high-melting-point components to low-melting-point components is preferably 20 / 80 to 80 / 20, and more preferably 30 / 70 to 70 / 30.

[0026] The cross-sectional shape of the fiber is not particularly limited, and can be round (such as a circle or ellipse), angular (such as a triangle or square), irregular (such as a star or octave), or even segmented or hollow. In addition, additives such as antioxidants, light stabilizers, ultraviolet absorbers, neutralizing agents, nucleating agents, epoxy stabilizers, lubricants, flame retardants, antistatic agents, pigments, or plasticizers may be included as needed, to the extent that they do not hinder the effects of the present invention.

[0027] The fineness of the fibers is not particularly limited, but examples include 0.6 to 5.0 dtex. In particular, when used as a surface material for absorbent articles such as disposable diapers, using lower fiber fineness results in a better texture for nonwoven fabrics and textile products. Furthermore, lower fineness results in a smoother texture, which reduces friction with the skin and can suppress rashes and other skin irritations. On the other hand, from the viewpoint of processability, handling, and production costs, it is preferable to have a certain degree of fineness. From this viewpoint, a fiber fineness of 1.3 to 2.6 dtex is more preferable.

[0028] (Non-woven fabric) Because the nonwoven fabric of the present invention contains the aforementioned fibers, it has excellent antibacterial properties, is bulky, has a smooth texture, and can be produced at low cost.

[0029] The nonwoven fabric of the present invention may contain fibers other than the fibers of the present invention as needed, as long as it does not impair the effects of the present invention. The proportion of such fibers is not particularly limited, but can be 1 to 30% by weight relative to the weight of the nonwoven fabric. If the proportion of fibers other than the fibers of the present invention is 1% by weight or more, an effect commensurate with use can be obtained, and if it is 30% by weight or less, satisfactory antibacterial properties can be obtained, as well as problems that occur in the carding process, such as poor fiber dispersion and discharge, can be reduced. In this case, it is preferable that the amount of component A attached to the entire nonwoven fabric be 0.02% by weight or more, and the amount of component B attached be 0.01% by weight or more. Specifically, when 70% by weight of fibers with 0.06% by weight of component A and 0.05% by weight of component B attached, and 30% by weight of fibers with neither component A nor component B attached, component A will be 0.02% by weight or more of the entire nonwoven fabric, thus providing excellent antibacterial properties. In addition, since component B will be 0.01% by weight or more of the entire nonwoven fabric, problems in the carding process can be reduced. Examples of fibers other than the fibers of the present invention include 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, in which components A and B are outside the range of adhesion amounts described above.

[0030] The nonwoven fabric of the present invention may be a single-layer nonwoven fabric, or it may be a laminate of two or more nonwoven fabrics with different fineness, composition, density, etc. In the case of a laminate of two or more nonwoven fabrics, for example, by laminating nonwoven fabrics composed of fibers with different fineness and composition, the size of the gaps formed between the fibers and the degree of hydrophilicity can be changed, thereby controlling the texture and hydrophilicity of the nonwoven fabric.

[0031] The nonwoven fabric of the present invention is not particularly limited, but may be a laminate of the nonwoven fabric with a sheet that does not contain the fibers of the present invention (a sheet other than the nonwoven fabric of the present invention). Examples of the sheet that does not contain the fibers of the present invention include webs, through-air nonwoven fabrics, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics, needle-punched nonwoven fabrics, films, meshes, nets, or woven or knitted fabrics. By laminating with such sheets, various physical properties such as texture, durable hydrophilicity, and strength can be controlled. Examples of methods for obtaining such a laminate include laminating a web containing the fibers of the present invention with a web that does not contain the fibers of the present invention and integrating them by a through-air method, or preparing the nonwoven fabric of the present invention and the sheet that does not contain the fibers of the present invention separately and laminating them together by adhesive or calendering.

[0032] The nonwoven fabric of the present invention may be subjected to antistatic treatment, water-repellent treatment, hydrophilic treatment, antibacterial treatment, ultraviolet absorption treatment, near-infrared absorption treatment, or electret treatment, depending on the purpose, as long as it does not impair the effects of the present invention.

[0033] The basis weight of the nonwoven fabric is not particularly limited, but is typically between 8 and 40 g / m². 2 It can be done as 10-30g / m 2 It is preferable that it be so.

[0034] The thickness of the nonwoven fabric is not particularly limited, but can be 0.2 to 4.0 mm, and more preferably 0.4 to 2.0 mm.

[0035] The antibacterial activity value of the nonwoven fabric is not particularly limited, but it is preferably 2 or higher, and more preferably 4 or higher. The method for evaluating the antibacterial activity value will be explained in the examples.

[0036] The nonwoven fabric of the present invention is not particularly limited and can be suitably used in a variety of textile products where antibacterial properties are required, such as absorbent articles like diapers, napkins, or incontinence pads; sanitary materials like masks, gowns, or surgical gowns; interior materials like wall sheets, shoji paper, or flooring materials; lifestyle-related materials like cover cloths, cleaning wipers, or garbage covers; toiletry products like disposable toilets or toilet covers; pet supplies like pet sheets, pet diapers, or pet towels; industrial materials like wiping materials, filters, cushioning materials, oil absorbents, or ink tank absorbents; general medical materials; bedding materials; and nursing care products. It is particularly suitable as a surface material for absorbent articles where smoothness of texture is important, such as diapers, napkins, or incontinence pads.

[0037] (Method of manufacturing fibers) The method for producing the fibers of the present invention is not particularly limited, but examples include a method of applying a fiber treatment agent, which is a mixture of component A and component B, to the fibers, and a method of applying component A (topcoating) on ​​top of component B which has been applied to the fibers. Furthermore, the method of application is not particularly limited, and the fibers can be applied after the spinning process, the drawing process, or the drying process by known methods such as contact with an oiling roll, immersion in an immersion tank, or spray application. In particular, the method of applying a fiber treatment agent, which is a mixture of component A and component B, to the fibers by contact with an oiling roll after the spinning process or the drawing process is preferred because it allows for uniform application of component A and component B, and the effects of the present invention become even more pronounced.

[0038] (Method of manufacturing nonwoven fabrics) The method for manufacturing the nonwoven fabric of the present invention is not particularly limited, but examples include a method in which a web containing the fibers of the present invention described above is made by a carding method, and the obtained web is integrated by a through-air method, a spunlace method, or a needle punch method. The nonwoven fabric of the present invention has the characteristics of being smooth and bulky because the web is made by a carding method. The method for integrating the web is preferably the through-air method, which results in a smooth texture. In the present invention, "web" refers to a fiber aggregate in which the fibers are loosely intertwined to the extent that it can maintain a sheet-like shape, and means a state in which the fibers are not adhered to each other or are not tightly intertwined. [Examples]

[0039] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The methods or definitions for measuring the physical properties shown in the examples are shown below.

[0040] <Fiber treatment agent> Table 1 shows the compositions of the fiber treatment agents (1) to (12) to be attached to the fibers of the present invention. The values ​​for each component in Table 1 represent the weight percentage of the fiber treatment agent.

[0041] [Table 1]

[0042] The components of the fiber treatment agents in Table 1 are abbreviated as follows: A1: ε-Polylysine B1: 1-(2-hydroxyethyl)-1-ethyl-2-pentadecyl-2-imidazolium ethyl sulfate B2: Trimethyltetradecylammonium chloride C1: Hexaglycerin monostearate C2: Stearamide EO(20) adduct C3: Polyoxyethylene alkyl ether (C=12~15) C4: Castor oil oleic acid adduct C5: (Mono, di) glycerides of fatty acids with 14 to 18 carbon atoms (however, fatty acids with 18 carbon atoms are unsaturated fatty acids) D1: Sodium di-2-ethylhexyl sulfosuccinate D2: Sodium dioctyl sulfosuccinate Other 1: Polyether compound (EO(20)·PO(10)) Other 2: Block copolymer of polyether with (-C2H4O-) as the repeating unit and polyester with (-C5H 10 COO-) as the repeating unit Other 3: Polyoxyalkylene-modified silicone Other 4: Trimethylolpropane PO·EO copolymer adduct

[0043] <Fineness of fiber> In accordance with JIS L 1015, the fineness of the fiber was measured.

[0044] <Adhesion amount of fiber treatment agent> Using 2 g of the web formed from the fiber on a roller card tester, the measurement was carried out with a rapid residual fat extraction device OC-1 type manufactured by Intec Co., Ltd. As the extraction solvent, 25 ml of methanol was used. The liquid dropped from the 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 by the following formula. Adhesion amount (weight%) = (weight of residue (g) / 2 (g)) × 100

[0045] <Adhesion amounts of component A, component B, component C, component D and other components> From the adhesion amount of the fiber treatment agent and the composition ratios in Table 1, the adhesion amounts of each component were calculated.

[0046] <Antibacterial test> Antimicrobial activity tests were conducted according to the bacterial suspension absorption method specified in JIS L1902:2015. A nonwoven fabric sterilized by UV irradiation was uniformly inoculated with the test bacterial solution, and a sterilized cap was tightened. This was then incubated at 37±1°C for 18 hours, and the number of viable bacteria after incubation was measured. Two types of samples were used: standard cotton cloth and nonwoven fabric prepared in each example. Escherichia coli (NBRC3301) and Staphylococcus aureus (NBRC12732) were used as test bacteria. The antimicrobial activity value, an indicator of antimicrobial activity, was calculated using the following formula. Antimicrobial activity value = (logC t -logC0)-(logT t -logT0) Here, logC0: the average number of bacteria collected immediately after inoculation of the standard cloth, logC t :Average number of bacteria collected after 18 hours of incubation of standard fabric, logT0:Average number of bacteria collected immediately after inoculation of processed fabric, logT t This shows the average number of bacteria collected after 18 hours of incubation of the processed fabric. Antibacterial properties were judged according to 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 greater, but less than 4. ×: The smaller of the antibacterial activity values ​​against Escherichia coli and Staphylococcus aureus is less than 2.

[0047] <Card processing capabilities> When passing the fibers through the roller carding machine, we visually inspected for phenomena such as the raw cotton not being properly entangled and flying up (flying), the web not being discharged from the roll due to static electricity, and the formation of fiber clumps (neps) in the web, and evaluated the carding processability based on the following criteria. ○: Even after operating for more than 8 hours, no phenomena such as fly, nep, or carding defects due to static electricity occurred. ×: Within 8 hours of starting operation, phenomena such as fly, nep, or poor carding properties due to static electricity occurred.

[0048] [Example 1] A concentric sheath-core 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 a stretching process, an aqueous solution of fiber treatment agent (1) diluted with deionized water was brought into contact with an oiling roll to adhere to the fiber surface so that the amount of fiber treatment agent (1) attached to the fiber surface was approximately 0.5% by weight relative to the fiber weight. Subsequently, crimping was applied and the fibers were dried, and the fibers were cut to a length of 51 mm to obtain the fibers. Next, the fibers were formed into a card web using a roller carding machine, and this web was processed at 130°C in a suction dryer to obtain a nonwoven fabric.

[0049] [Example 2] A concentric sheath-core 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 a stretching process, crimping was applied, and the fiber surface was coated with an aqueous solution of fiber treatment agent (1) diluted with ion-exchanged water, so that the amount of fiber treatment agent (1) attached was approximately 0.5% by weight relative to the fiber weight. The fibers were then dried and cut to a length of 51 mm to obtain the fibers. Next, a nonwoven fabric was obtained in the same manner as in Example 1.

[0050] [Examples 3-5, Comparative Examples 1-8] As shown in Table 2, fibers and nonwoven fabrics were obtained in the same manner as in Example 1, except that the fiber treatment agent was changed.

[0051] Tables 2 and 3 show the results for the fineness of the fibers obtained in Examples 1-5 and Comparative Examples 1-8, the amount of each component attached, antibacterial properties, and carding properties.

[0052] [Table 2]

[0053] [Table 3]

[0054] As shown in Table 2, Comparative Example 4 did not contain component A, and Comparative Example 8 had a low amount of component A (0.01% by weight), resulting in low antibacterial properties compared to Examples 1, 3, and 4. This indicates that excellent antibacterial properties are observed when component A is present at a concentration of 0.02% by weight or more relative to the fiber weight. Furthermore, Comparative Example 5, which did not contain component B, had poor carding properties. And Comparative Example 6, which did not contain either component A or component B, exhibited poor antibacterial properties and carding properties. Therefore, in order to exhibit excellent antibacterial properties and carding properties, it is necessary for both component A and component B to be present in predetermined amounts. Furthermore, in Comparative Examples 1-3, where a large amount of component D was present, the antibacterial activity was low. This is thought to be because component D inhibited the antibacterial effect of polylysine. Furthermore, a comparison of Example 1 and Example 2 suggests that even with equivalent amounts of the adhering components to the fibers, there are differences in antibacterial properties depending on the application method. It is believed that the method in Example 1 resulted in a higher antibacterial effect due to improved uniformity of adhesion. [Industrial applicability]

[0055] The antibacterial fibers of the present invention possess excellent antibacterial properties and carding properties, and can be obtained at low cost. Therefore, they can be suitably used in a variety of textile products that require antibacterial properties and a smooth texture, such as absorbent articles like diapers, napkins, or incontinence pads; sanitary materials like masks, gowns, or surgical gowns; interior materials like wall sheets, shoji paper, or flooring materials; lifestyle-related materials like cover cloths, cleaning wipers, or garbage covers; toiletries like disposable toilets or toilet covers; pet supplies like pet sheets, pet diapers, or pet towels; industrial materials like wiping materials, filters, cushioning materials, oil absorbents, or ink tank absorbents; general medical materials; bedding materials; and nursing care products.

Claims

1. A fiber composed of at least one thermoplastic resin, wherein the surface of the fiber has the following components A and B attached to it, the amount of component A attached is 0.02 to 0.06% by weight relative to the fiber weight, and the amount of component B attached is 0.01% by weight or more relative to the fiber weight. Component A: Polylysine or its salt Ingredient B: Cationic surfactant

2. The fiber according to claim 1, wherein the polylysine is ε-polylysine.

3. The fiber according to claim 1 or 2, to which the following component C is attached. Component C: Polyalkylene oxide-added nonionic surfactant or polyhydric alcohol-type nonionic surfactant

4. The fiber according to claim 1 or 2, wherein the cationic surfactant is an alkylimidazolium alkyl sulfate salt represented by general formula (1). (In the formula, R １ R is an alkyl group having 7 to 21 carbon atoms. ２ (This refers to a methyl group or an ethyl group.)

5. The fiber according to claim 1 or 2, wherein the fiber is a concentric sheath-core composite fiber, an eccentric sheath-core composite fiber, or a parallel composite fiber.

6. The fiber according to claim 5, wherein at least one of the thermoplastic resins constituting the composite fiber is a polyolefin resin.

7. A nonwoven fabric comprising the fibers described in claim 1 or 2.

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