Method for evaluating fiber material

Abstract

In a method for evaluating a fiber material (10), a coloration test or a color fading test is performed. In the coloration test, the fiber material is immersed in an acidic liquid, and it is checked whether the quaternary ammonium salt test paper is colored by immersing the quaternary ammonium salt test paper in the acidic liquid. By so doing, it is possible to evaluate whether the fiber material exhibits antiviral performance. In the color fading test, the fiber material is immersed in an iodine aqueous solution, and it is checked whether the iodine aqueous solution, which exhibits a blue-violet color caused by an iodine-starch reaction, fades in color. By so doing, it is possible to evaluate whether the fiber material exhibits antibacterial performance.

Description

Fiber material evaluation method

[0001] The present invention relates to a method for evaluating a fibrous material.

[0002] It is predicted that a living body wearing clothing that exhibits antiviral properties will be less susceptible to viral infection. In the case of a human being, it is expected that the living body will be prevented from contracting a disease caused by the virus. From this perspective, the present applicant has proposed in International Publication No. 2017 / 199420 a textile material that supports Al-doped zinc oxide on its surface and exhibits antiviral properties.

[0003] Clothing is washed repeatedly. There is a demand for a simple method for evaluating whether clothing (textile materials) maintain their antiviral properties after repeated washing. However, a simple and easy evaluation method for textile materials with such functionality has not yet been established.

[0004] The present invention aims to solve the above-mentioned problems.

[0005] According to one embodiment of the present invention, there is provided a method for evaluating textile materials, which evaluates textile materials including a fiber body containing at least one of cellulosic fibers, animal fibers, and synthetic fibers by a color test, in which the textile material is immersed in an acetic acid solution, and a color test is performed in which a quaternary ammonium salt test paper is immersed in the acetic acid solution to check whether the quaternary ammonium salt test paper changes color in the color test, and if the quaternary ammonium salt test paper changes color in the color test, it is determined that first particles containing a quaternary ammonium salt are retained on the surface of the fiber body.

[0006] According to another embodiment of the present invention, there is provided a method for evaluating a textile material including a fiber body containing at least one of cellulosic fiber, animal fiber, and synthetic fiber by a discoloration test, in which the textile material is immersed in an iodine aqueous solution, and a discoloration test is conducted to check whether the iodine aqueous solution, which has turned blue-purple due to the iodine-starch reaction, has discolored. If the iodine aqueous solution has discolored in the discoloration test, it is determined that second particles made of a metal oxide capable of reducing iodine are retained on the surface of the fiber body.

[0007] According to yet another embodiment of the present invention, there is provided a method for evaluating a textile material, which includes a fiber body containing at least one of cellulosic fiber, animal fiber, and synthetic fiber, by a color test and a color fading test. The method comprises the steps of: a color test in which the textile material is immersed in an acetic acid solution and a quaternary ammonium salt test paper is immersed in the acetic acid solution to determine whether the quaternary ammonium salt test paper changes color; and a color fading test in which the textile material is immersed in an iodine aqueous solution to determine whether the iodine aqueous solution, which has turned blue-purple due to an iodine-starch reaction, fades. If the quaternary ammonium salt test paper changes color in the color test, it is determined that first particles containing a quaternary ammonium salt are retained on the surface of the textile body. If the iodine aqueous solution fades in the color fading test, it is determined that second particles made of a metal oxide capable of reducing iodine are retained on the surface of the textile body.

[0008] When the quaternary ammonium salt test paper changes color, it can be determined that the quaternary ammonium salt (first particles) is supported on the surface of the fiber body. Since the quaternary ammonium salt mainly exhibits antiviral performance, in this case, it can be evaluated that the fiber exhibits antiviral performance.

[0009] If the iodine solution fades, it can be determined that metal oxide (second particles) is supported on the surface of the fiber body. Since metal oxides primarily exhibit antibacterial properties, in this case, it can be evaluated that the fiber material exhibits antibacterial properties.

[0010] According to the above evaluation method, it is possible to evaluate whether a textile material exhibits antiviral or antibacterial activity based on the presence or absence of a color change in the quaternary ammonium salt test paper or the presence or absence of a color change in the iodine aqueous solution. Moreover, since the evaluation can be done visually, the evaluation method is simple.

[0011] FIG. 1 is an enlarged plan view of a main portion of a woven fabric obtained from a fibrous material. FIG. 2 is a schematic cross-sectional view of the fibrous material as viewed from a direction perpendicular to the longitudinal direction. FIG. 3 is a schematic flow diagram of a method for producing a fibrous material. FIGS. 4A and 4B are schematic flows of a method for evaluating a fibrous material. FIG. 5 is a schematic diagram showing the degree of fading of an iodine aqueous solution over time. FIG. 6 is a diagram showing the relationship between the concentration of each component in the treatment solution and the durability of antiviral and antibacterial performance in a fibrous material. FIG. 7 is a diagram showing the relationship between the concentration of each component in the treatment solution and the durability of antibacterial performance in another fibrous material.

[0012] In the following embodiment, a woven fabric 30 (see FIG. 1 ) obtained from the fiber material 10 will be described as an example. However, the form of the fiber material 10 is not limited to the woven fabric 30. For example, other textiles, yarns, cotton, fiber bundles, woven fabrics, knitted fabrics, nonwoven fabrics, etc. may be obtained from the fiber material 10 in addition to the woven fabric 30. The fiber material 10 may also be a towel having pile yarns.

[0013] First, referring to Figure 1, a woven fabric 30 exhibiting antibacterial and antiviral properties will be described. Figure 1 is an enlarged plan view of a main portion of the woven fabric 30 obtained from the fiber material 10. The woven fabric 30 is obtained by weaving warp yarns 32 made of the fiber material 10 and weft yarns 34 made of the fiber material 10. The warp yarns 32 and weft yarns 34 may be single yarns or two-ply yarns. Furthermore, the woven fabric 30 may be a yarn spun by a drawing process after conventional functional processing of cotton. Note that Figure 1 shows the woven fabric 30 obtained by plain weaving. However, the woven fabric 30 may also be obtained by twill weaving or satin weaving.

[0014] The fiber material 10 has been subjected to predetermined treatments such as scouring and bleaching, and has also been subjected to a supporting treatment, which will be described later. The woven fabric 30 may or may not be dyed.

[0015] 2, the fibrous material 10 includes a fiber body 12, a binder film 14, and support particles 20. The support particles 20 include first particles 16 containing a quaternary ammonium salt and second particles 18 made of a metal oxide.

[0016] The fiber body 12 contains at least one of cellulosic fiber, animal fiber, and synthetic fiber. In other words, the material of the fiber body 12 may be only one of cellulosic fiber, animal fiber, and synthetic fiber, or may be two or more of cellulosic fiber, animal fiber, and synthetic fiber. The proportion of cellulosic fiber, animal fiber, and synthetic fiber in the fiber body 12 can be set within a desired range.

[0017] A typical example of a cellulosic fiber is cotton, a natural plant fiber. Other examples of cellulosic fibers include ramie, linen, hemp, jute, Manila hemp, sisal, and other hemp. The cellulosic fiber may be a regenerated fiber. Regenerated fibers are obtained by dissolving natural cellulose in a specific solvent and then forming it into a fibrous form. Specific examples of regenerated fibers include rayon, Polynosic, cupra, and Tencel (a registered trademark of Rensing GmbH, Austria).

[0018] Representative examples of animal fibers include silk, wool, and animal hair fibers. Specific examples of animal hair fibers include alpaca, mohair, angora, cashmere, camel, and buccuna. Examples of synthetic fibers include polyester, polyurethane, aliphatic polyamide fibers (such as nylon 6 or nylon 6,6), and aromatic polyamide fibers.

[0019] For example, when the fiber body 12 contains cellulosic fibers and animal fibers, the woven fabric 30 may be a fabric made using raw yarns of both fibers (blended yarns or twisted yarns), or may be a cross-woven fabric made using raw yarns of cellulosic fibers and raw yarns of animal fibers.

[0020] First particles 16 containing a quaternary ammonium salt and second particles 18 containing a metal oxide are supported on the surface of the fiber body 12 via a binder film 14. The quaternary ammonium salt is a complex or association of a quaternary ammonium cation and an anion that is bonded to the quaternary ammonium cation as a counterion by electrostatic action. - When the formula is expressed as follows, the general formula of the quaternary ammonium salt is expressed as follows:

[0021]

[0022] Here, typical examples of R1 are alkyl groups or alkoxysilane groups. Typical examples of R2 and R3 are methyl groups or ethyl groups. A preferred value for n is an integer between 6 and 18, and a more preferred value for n is 10 or 11. Typical examples of X are halogen or organic acids. In one embodiment, the first particles 16 containing a quaternary ammonium salt are solubilized in an anion-rich solution. In this case, the first particles 16 are encapsulated in association bodies of anionic surfactants contained in the anion-rich solution.

[0023] The quaternary ammonium salt may be a polymer type or a silane type. When the quaternary ammonium salt is a polymer type, the repeating unit preferably has a main chain carbon number of 7 to 12 and a molecular weight of 200 to 240. The polymer type quaternary ammonium salt may be a condensation polymer of a compound having a quaternary ammonium group and an amine compound. In this case, the preferred molecular weight of the monomer is in the range of 200 to 240.

[0024] Quaternary ammonium salts exhibit cationic properties. In contrast, in an anion-rich aqueous solution containing a quaternary ammonium salt and an anionic surfactant in a concentration range of 40 to 100 mM, and in which the molar concentration of the anionic surfactant is adjusted to at least four times the molar concentration of the quaternary ammonium salt, an association of the quaternary ammonium salt and the anionic surfactant is formed. Alternatively, an anionic surfactant association encapsulating a complex of the quaternary ammonium salt and the anionic surfactant is formed and solubilized. As a result, a liquid containing a quaternary ammonium salt and an anionic surfactant exhibits anionic properties.

[0025] Suitable examples of anionic surfactants include phosphate ester surfactants, sulfate ester surfactants, carboxylic acid surfactants, and sulfonic acid surfactants. When a phosphate ester surfactant is used, the alkyl group substituted for H in the hydroxyl group of the phosphoric acid is preferably an alkyl group having 8 to 12 carbon atoms. The molecular weight of the phosphate ester surfactant is preferably in the range of 250 to 380. Furthermore, the phosphate ester surfactant is preferably a dehydration condensation product of a primary alcohol having any number of carbon atoms and tetraphosphorus hexaoxide, and has a molecular weight in the range of 250 to 380. The dehydration condensation product may be any of a mono-type, a di-type, or a mixture of a mono-type and a di-type.

[0026] The first particles 16 having the above-described quaternary ammonium salt as a base material mainly exhibit antiviral properties.

[0027] If the woven fabric 30 is not dyed, a user may wish to dye the woven fabric 30. If the quaternary ammonium salt is cationic, the dye tends to be attracted to the quaternary ammonium cation. This may result in dye spots. To avoid this problem, it is preferable that the quaternary ammonium salt is solubilized as a result of being encapsulated in an aggregate of an anionic surfactant at a molar concentration of at least four times the quaternary ammonium salt, and that the charge of the entire dispersion be anionic.

[0028] As the metal oxide, a substance that exhibits antibacterial properties and can reduce iodine is mainly used. Specific examples of such metal oxides include zinc oxide (ZnO), titanium oxide (TiO2), and tin oxide (SnO2). Of these, ZnO is most preferable because it has the highest reducing power for iodine. ZnO may be doped with a Group 13 element to improve its reducing power for iodine. A typical example of a Group 13 element is aluminum (Al).

[0029] The first particles 16 containing a quaternary ammonium salt and the second particles 18 made of a metal oxide are held on the surface of the fiber body 12 via a binder film 14. The binder film 14 is, for example, a film made of a silicone-based binder or a urethane-based binder. It is preferable to form the binder film 14 using a combination of a silicone-based binder and a urethane-based binder. This improves the washing durability of the antiviral and antibacterial properties of the fiber material 10. In the case of a combination, the binder film 14 may be a single film made of a physical mixture of a silicone-based binder and a urethane-based binder. Alternatively, the binder film 14 may be a compound film in which a silicone-based binder and a urethane-based binder are chemically bonded.

[0030] As will be shown in the cotton-processed knit described later, even if the textile material 10 is cotton, the second particles 18 can be attached to the surface of the cotton by co-treating it with a metal oxide and a silicone binder. This makes it possible to impart sufficient washing durability to the antibacterial properties of the cotton.

[0031] The binder film 14 is physically fixed to the surface of the fiber body 12 mainly by mechanical action such as the anchor effect. That is, the majority of functional groups in the fiber body 12 are not chemically bonded to either the functional groups of the silicone-based binder or the functional groups of the urethane-based binder. Therefore, the functional groups in the fiber body 12 exhibit sufficient activity toward the dye. Moreover, the dye easily passes through the binder film 14. Furthermore, the functional groups in the fiber body 12 are hydrophilic and attract water molecules.

[0032] For the reasons described above, the fiber body 12 is easily dyed, even though the first particles 16 and the second particles 18 are supported on the surface via a silicone-based binder and a urethane-based binder. That is, the fiber material 10 has excellent dyeability. Therefore, it is possible to perform so-called piece dyeing on the fiber material 10 after the supporting treatment.

[0033] Therefore, while storing the woven fabric 30 in an undyed state, it is possible to collect information on trendy colors, dye the fabric 30 based on that information, and then ship the finished product. In other words, it is possible to provide products that accurately capture rapidly changing fashion colors or patterns in a short period of time. This reduces dead stock of the fiber material 10 and the woven fabric 30. However, it is also possible to obtain the fiber material 10 by performing a support treatment on the fiber body 12 after dyeing.

[0034] Furthermore, the binder film 14 exhibits good elasticity. Therefore, when the woven fabric 30 is deformed, the binder film 14 deforms accordingly. This allows the binder film 14 to remain firmly attached to the surface of the fiber body 12. Therefore, the first particles 16 and the second particles 18 are maintained supported on the surface of the fiber body 12 via the binder film 14.

[0035] Therefore, even if frictional force or the like is applied to the woven fabric 30 in water while the woven fabric 30 is being washed, the binder film 14, the first particles 16, and the second particles 18 are prevented from falling off the surface of the fiber body 12. As a result, the antiviral and antibacterial properties of the woven fabric 30 (fiber material 10) are maintained for a long period of time.

[0036] Specifically, after washing the textile material 10 100 times, the antiviral activity values ​​(Mv) for influenza A virus and SARS-CoV-2 mutant strain (Omicron strain) were 2.1 and 3.3, respectively. In influenza A virus, the nucleic acid encapsulated by the capsid is RNA. In addition, influenza A virus has an envelope.

[0037] Furthermore, after the fabric material 10 was washed 100 times, the antibacterial activity values ​​(A) for Staphylococcus aureus, Moraxella, Escherichia coli, and Klebsiella pneumoniae were 6.0, 6.1, 6.2, and 6.0, respectively.

[0038] The above-described fiber material 10 can be obtained, for example, by the manufacturing method described below. As shown in Fig. 3, this manufacturing method includes a dipping step S1 and a heating step S2. The dipping step S1 and the heating step S2 are support treatments for supporting the first particles 16 and the second particles 18 on the surface of the fiber body 12.

[0039] First, an anion-rich aqueous solution is prepared. Specifically, a quaternary ammonium salt and an anionic surfactant are added to the aqueous solvent so that the total concentration is in the range of 40 to 100 mM. Here, the molar concentration of the anionic surfactant is at least four times that of the quaternary ammonium salt. By adjusting the molar concentrations of the anionic surfactant and the quaternary ammonium salt as described above, the aqueous solution becomes anion-rich. The quaternary ammonium salt and the anionic surfactant form the above-mentioned complex or aggregate. However, the complex is encapsulated in the anionic surfactant aggregate and, as a result, is solubilized. Hereinafter, the complex or aggregate of the quaternary ammonium salt and the anionic surfactant may be referred to as an "anionic dispersion."

[0040] Specific examples of the anionic surfactant include the phosphate ester surfactants, sulfate ester surfactants, carboxylic acid surfactants, and sulfonic acid surfactants, as described above.

[0041] Metal oxide particles, a silicone-based binder, and a urethane-based binder are added to and dispersed in the aqueous solution containing the anionic dispersion, thereby preparing an anion-rich aqueous dispersion. In the aqueous dispersion, the concentration of the anionic dispersion is adjusted to, for example, 0.5 to 20%. In the aqueous dispersion, the concentration of the metal oxide is adjusted to, for example, 0.2 to 10%. In the aqueous dispersion, the concentrations of the silicone-based binder and the urethane-based binder are each adjusted to, for example, 0.1 to 10%.

[0042] Silicone compounds and urethane compounds are generally anionic and tend to chemically aggregate with quaternary ammonium cations. In contrast, in the anion-rich aqueous dispersion, the quaternary ammonium cations form anionic dispersions with anionic surfactants at a molar concentration four times or more that of the quaternary ammonium cations. The anionic dispersions are soluble in aqueous solvents. Therefore, the aqueous dispersions are anionically charged. Therefore, chemical aggregation between the anionic dispersions and the silicone compounds and urethane compounds is suppressed.

[0043] Next, in the immersion step S1, the fiber body 12 is immersed in the aqueous dispersion. At this point, the fiber body 12 may be a single body before being woven, or may have been woven into a woven fabric 30 or the like. By immersing the fiber body 12 (or the woven fabric 30) in the aqueous dispersion, silicone-based compounds, urethane-based compounds, quaternary ammonium salts, and metal oxides adhere to the surface of the fiber body 12. In particular, when an aqueous dispersion containing an anionic surfactant in an anion-rich state is used, the silicone-based compounds, urethane-based compounds, quaternary ammonium salts, and metal oxides easily reach the surface of the fiber body 12.

[0044] Thereafter, the liquid is squeezed out, and the fiber material 10 is subjected to a heating treatment in a heating step S2. The fiber material 10 may be dried before the heating treatment is performed. In other words, a drying step may be performed between the immersion step S1 and the heating step S2.

[0045] The heat treatment causes crosslinking between the silicone compound and the urethane compound, forming a binder film 14. Furthermore, particles containing a quaternary ammonium salt (first particles 16) and particles made of a metal oxide (second particles 18) are supported on the surface of the fiber body 12 via the binder film 14. As a result, the fiber material 10 is obtained. The heat treatment can be carried out by, for example, dry heat treatment or steam setting.

[0046] In the fibrous material 10 obtained through the above process, as shown in Figure 2, the binder film 14 is physically bonded to the surface of the fiber body 12 mainly by the anchor effect. The binder film 14 freely deforms in response to deformation of the fibrous material 10. Therefore, the first particles 16 and the second particles 18 are less likely to fall off from the surface of the fiber body 12. Furthermore, the first particles 16 and the second particles 18 provide the fibrous material 10 with effective antiviral and antibacterial properties against, for example, influenza A virus, Staphylococcus aureus, and Klebsiella pneumoniae.

[0047] Furthermore, in the fiber material 10, the functional groups of the fiber body 12 are in an active state that allows them to chemically bond with dyes. This gives the fiber material 10 excellent dyeability. Therefore, the fiber material 10 can be easily piece-dyed. Furthermore, when the quaternary ammonium cation forms an anionic dispersion together with the anionic surfactant, the dye can easily reach the surface of the fiber body 12. Therefore, in this case, the fiber material 10 can be even more easily piece-dyed.

[0048] Next, a method for evaluating the fiber material 10 according to this embodiment will be described. This evaluation method is a method for visually evaluating whether or not the fiber material 10 has antiviral and antibacterial properties.

[0049] Specifically, the evaluation method includes a color test and a color fading test, as shown in FIG. 4A . It is possible to determine whether the textile material 10 exhibits antiviral performance based on the results of the color test. It is also possible to determine whether the textile material 10 exhibits antibacterial performance based on the results of the color fading test. The color test and the color fading test can be performed in any order. That is, for the same textile material 10, the color fading test may be performed after the color fading test, as shown in FIG. 4A , or the color test may be performed after the color fading test, as shown in FIG. 4B .

[0050] The following describes an example of evaluating the antiviral and antibacterial properties of the woven fabric 30. In this case, a color test and a color fading test can be performed on the woven fabric 30. In other words, there is no need to unravel the woven fabric 30 or to dissolve the woven fabric 30.

[0051] In the coloration test, the woven fabric 30 is immersed in an acetic acid solution adjusted to a pH of 3 to 4 at 50 to 100°C. In this state, a quaternary ammonium salt test paper is immersed in the acetic acid solution. If the quaternary ammonium salt (first particles 16) is supported on the woven fabric 30, the quaternary ammonium salt test paper will be green or blue. Based on this coloration, it can be determined that the quaternary ammonium salt (first particles 16) is supported on the woven fabric 30. Furthermore, the woven fabric 30 exhibits antiviral performance based on the presence of the quaternary ammonium salt. Therefore, based on the green or blue coloration of the quaternary ammonium salt test paper, it can be evaluated that the woven fabric 30 exhibits antiviral performance due to the quaternary ammonium salt.

[0052] In contrast, the color of the quaternary ammonium salt test paper does not change when the quaternary ammonium salt (first particles 16) has fallen off from the woven fabric 30. Based on this, it can be evaluated that the woven fabric 30 has lost the antiviral performance due to the quaternary ammonium salt.

[0053] In the color fading test, the woven fabric 30 is immersed in an iodine aqueous solution, and then a starch aqueous solution is added to the iodine aqueous solution and allowed to stand. The iodine-starch reaction between the starch and iodine proceeds rapidly, causing the iodine aqueous solution to assume a bluish-purple color. If a metal oxide (second particles 18) is supported on the woven fabric 30, the iodine is reduced by the metal oxide when the woven fabric 30 is allowed to stand in this state. Accordingly, as shown in the "Antibacterial Performance" column in FIG. 5 , the iodine aqueous solution changes from bluish-purple to transparent over time. That is, the bluish-purple color of the iodine aqueous solution fades.

[0054] Based on this discoloration, it can be determined that metal oxide (second particles 18) is supported on the woven fabric 30. Furthermore, the woven fabric 30 exhibits antibacterial properties based on the presence of metal oxide. Therefore, based on the discoloration of the iodine solution, it can be evaluated that the woven fabric 30 exhibits antibacterial properties due to metal oxide.

[0055] In contrast, when the metal oxide (second particles 18) has fallen off from the woven fabric 30, the iodine aqueous solution does not fade over time, as shown in the "No antibacterial performance" column in Figure 5. Alternatively, the iodine aqueous solution fades slowly. Based on this, it can be evaluated that the woven fabric 30 has lost the antibacterial performance provided by the metal oxide.

[0056] As described above, by performing the coloration test and the color fading test, it is possible to visually evaluate whether the woven fabric 30 exhibits antiviral and antibacterial properties. Therefore, it is easy to determine whether the woven fabric 30 maintains its antiviral and antibacterial properties after repeated washing of the woven fabric 30, for example.

[0057] Moreover, the color change test and the color fading test are non-destructive tests, so that after it is determined that the woven fabric 30 maintains its antiviral and antibacterial properties, the woven fabric 30 can continue to be used.

[0058] For ease of understanding, the above example illustrates a case in which the color fading test and color development test are performed using a known fiber material 10 obtained through the above manufacturing process. However, the color fading test and color development test can also be performed using an unknown fiber material. For example, if a color development test is performed on an unknown fiber material and no color development is observed on the quaternary ammonium salt test paper, the fiber material can be evaluated as not having antiviral properties due to the first particles 16. Furthermore, if a color fading test is performed on an unknown fiber material and no color fading is observed in the iodine aqueous solution, the fiber material can be evaluated as not having antibacterial properties due to the second particles 18.

[0059] Furthermore, in the above embodiment, both the color fading test and the color change test are performed using a known fiber material 10. In contrast, it is also possible to perform only either the color change test or the color change test on an unknown fiber material. As above, based on the color change test, it is possible to evaluate whether the fiber material exhibits antiviral performance due to the first particles 16. Furthermore, based on the color fading test, it is possible to evaluate whether the fiber material exhibits antibacterial performance due to the second particles 18.

[0060] This embodiment has the following advantages.

[0061] The first evaluation method for evaluating a known textile material 10 or an unknown textile material is a color test. In the color test, the textile material 10 is immersed in an acetic acid solution, and a quaternary ammonium salt test paper is immersed in the acetic acid solution to determine whether the quaternary ammonium salt test paper changes color. If the quaternary ammonium salt test paper changes color, it can be determined that the first particles 16 are retained on the surface of the fiber body 12. Since quaternary ammonium salts primarily exhibit antiviral properties, in this case, the textile material 10 can be evaluated as exhibiting antiviral properties.

[0062] The acetic acid solution used in the color test is a weak acid. In this case, deterioration of the fiber material 10 due to the acidic solution is avoided. Typically, the pH of the acidic solution is 4 or less, for example, in the range of 3 to 4. In addition, because acetic acid is relatively inexpensive, the cost of reagents and the like required for evaluating the fiber material 10 can be reduced.

[0063] The color test time is, for example, 15 seconds or less. This makes it possible to check whether the quaternary ammonium salt test paper has colored within 15 seconds after immersing the quaternary ammonium salt test paper in the acetic acid solution. If the quaternary ammonium salt test paper has not colored or has barely colored after 15 seconds, it can be determined that the amount of the first particles 16 (quaternary ammonium salt) remaining on the surface of the fiber body 12 is below the detection limit.

[0064] Furthermore, if the quaternary ammonium salt test paper shows no color or almost no color after 15 seconds have passed, it can be evaluated that the textile material 10 has lost the antiviral performance provided by the quaternary ammonium salt.

[0065] A second evaluation method for evaluating a known or unknown fiber material 10 is a discoloration test. In the discoloration test, the fiber material 10 is immersed in an iodine solution to determine whether the iodine solution, which has turned blue-purple due to the iodine-starch reaction, discolors. If the iodine solution discolors, it can be determined that the second particles 18 are retained on the surface of the fiber body 12. Because metal oxides primarily exhibit antibacterial properties, in this case, the fiber material 10 can be evaluated as exhibiting antibacterial properties.

[0066] The discoloration test time is, for example, less than 30 minutes. This makes it possible to check whether the iodine aqueous solution has discolored in less than 30 minutes after immersing the fiber material 10 in the iodine aqueous solution. If the iodine aqueous solution has not discolored or has only slightly discolored after 30 minutes, it can be determined that the amount of second particles 18 (metal oxide) remaining on the surface of the fiber body 12 is below the detection limit.

[0067] Furthermore, if the iodine aqueous solution has not faded or has barely faded after 30 minutes, the fiber material 10 can be evaluated as having lost the antibacterial properties provided by the metal oxide.

[0068] A third evaluation method for evaluating a known textile material 10 or an unknown textile material is a color test and a color fading test. Similar to the above, the color test can be used to evaluate whether the textile material 10 exhibits antiviral performance. The color fading test can also be used to evaluate whether the textile material 10 exhibits antibacterial performance. The color test and the color fading test can be performed in any order. That is, the color test can be performed after the color fading test, or the color test can be performed after the color fading test.

[0069] In this way, the above-described evaluation method makes it possible to visually evaluate whether the textile material 10 exhibits antiviral and antibacterial properties based on the presence or absence of a color change in the quaternary ammonium salt test paper and the presence or absence of a color change in the iodine aqueous solution. Moreover, the evaluation method is simple.

[0070] In addition to the above disclosure, the following additional notes are disclosed.

[0071] (Supplementary Note 1) The fibrous material (10) to be evaluated includes a fibrous body (12), which includes at least one of cellulosic fiber, animal fiber, and synthetic fiber.

[0072] In the first evaluation method, a color test is performed. In the color test, the fiber material is immersed in an acetic acid solution, and a quaternary ammonium salt test paper is immersed in the acetic acid solution to check whether the quaternary ammonium salt test paper changes color. If the quaternary ammonium salt test paper changes color, it can be determined that the first particles are retained on the surface of the fiber body. Since quaternary ammonium salts primarily exhibit antiviral properties, in this case, the fiber material can be evaluated as exhibiting antiviral properties. Moreover, since acetic acid is relatively inexpensive, the cost of reagents and the like required for evaluation can be reduced.

[0073] (Supplementary Note 2) In the evaluation method described in Supplementary Note 1, the pH of the acetic acid solution may be equal to or less than 4. In this case, deterioration of the fibrous material by the acetic acid solution can be avoided.

[0074] (Appendix 3) In the evaluation method described in Appendix 1 or Appendix 2, it may be possible to check whether the quaternary ammonium salt test paper has changed color within 15 seconds after immersing the quaternary ammonium salt test paper in the acetic acid solution. If the quaternary ammonium salt test paper has not changed color or has changed very little color after 15 seconds, it can be determined that the amount of the first particles (quaternary ammonium salt) remaining on the surface of the fiber body is below the detection limit.

[0075] (Note 4) In the second evaluation method, a discoloration test is performed. In the discoloration test, the fiber material is immersed in an iodine aqueous solution, and it is examined whether the iodine aqueous solution, which has turned blue-purple due to the iodine-starch reaction, fades. If the iodine aqueous solution fades, it can be determined that the second particles are retained on the surface of the fiber body. Since metal oxides primarily exhibit antibacterial properties, in this case, the fiber material can be evaluated as exhibiting antibacterial properties.

[0076] (Appendix 5) In the evaluation method described in Appendix 4, it may be possible to check whether the iodine aqueous solution has faded within 30 minutes after the fiber material has been immersed in the iodine aqueous solution. If the iodine aqueous solution has not faded or has barely faded after 30 minutes, it can be determined that the amount of second particles (metal oxide) remaining on the surface of the fiber body is below the detection limit.

[0077] (Supplementary Note 6) In the third evaluation method, a color test and a color fading test are performed in any order. As described above, the color test can be used to evaluate whether a textile material exhibits antiviral performance. The color fading test can be used to evaluate whether a textile material exhibits antibacterial performance.

[0078] According to the above evaluation method, whether or not a textile exhibits antiviral and antibacterial properties can be visually evaluated based on the presence or absence of a color change in the quaternary ammonium salt test paper and the presence or absence of a color change in the iodine aqueous solution. Moreover, since it is sufficient to check for the presence or absence of a color change, the evaluation method is simple.

[0079] (Supplementary Note 7) In the evaluation method described in Supplementary Note 6, the pH of the acetic acid solution may be 4 or less. The optimum pH is in the range of 3 to 4. In this case, deterioration of the fibrous material by the acetic acid solution is avoided. In addition, the efficiency of extracting metal oxides from the fibrous material is improved.

[0080] (Appendix 8) In the evaluation method described in Appendix 6 or Appendix 7, it may be possible to check whether the quaternary ammonium salt test paper has changed color within 15 seconds after immersing the quaternary ammonium salt test paper in the acetic acid solution. If the quaternary ammonium salt test paper has not changed color or has changed very little color after 15 seconds, it can be determined that the amount of the first particles (quaternary ammonium salt) remaining on the surface of the fiber body is below the detection limit.

[0081] (Appendix 9) In the evaluation method according to any one of Appendices 6 to 8, it may be possible to check whether the iodine aqueous solution has faded within 30 minutes of immersing the fiber material in the iodine aqueous solution. If the iodine aqueous solution has not faded or has barely faded after 30 minutes, it can be determined that the amount of second particles (metal oxide) remaining on the surface of the fiber body is below the detection limit.

[0082] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention.

[0083] In the following, "control" refers to towels or the like that have been immersed in a treatment solution described below and treated. The control has not been washed. "Sample" refers to towels or the like obtained by washing the control 100 times.

[0084] [Evaluation of antiviral performance] A plurality of towels were woven using 100% cotton two-ply yarn (40 / 2) with a count of 40 as the ground warp, 100% cotton single yarn (20 / 1) with a count of 20 as the weft, and 100% cotton single yarn (20 / 1) with a count of 20 as the pile warp, and each of the plurality of towels was scoured and bleached by a conventional method.

[0085] Meanwhile, a treatment liquid was obtained by adding a quaternary ammonium salt aqueous dispersion, a zinc oxide dispersion, a silicone-based binder dispersion, and a urethane-based binder dispersion to water and mixing them. Here, the quaternary ammonium salt aqueous dispersion was obtained by adding an anionic surfactant and a quaternary ammonium salt to an aqueous solvent. The cationic component of the quaternary ammonium salt was dodecyltrimethylammonium salt. The anionic surfactant was a dehydration condensate obtained by a conventional method from a mixture of 3 parts by mass of lauryl alcohol and 1 part by mass of tetraphosphorus decoxide (phosphoric anhydride). The anionic surfactant and the quaternary ammonium salt were added to the aqueous solvent so that the sum of the molar concentrations of the anionic surfactant and the quaternary ammonium salt was 43.5±1.0 mM, and the molar concentration of the anionic surfactant was at least four times that of the quaternary ammonium salt. As can be seen from the above, the treatment liquid is anion-rich.

[0086] DECBINDER-ST (product name) manufactured by Satoda Chemical Industries, Ltd. and SU-67 (product name) manufactured by Satoda Chemical Industries, Ltd. were used as the silicone-based binder and urethane-based binder, respectively. Furthermore, Z-SDN (product name) manufactured by Satoda Chemical Industries, Ltd. was used as the zinc oxide. Z-SDN is a liquid containing zinc oxide as an active ingredient. Furthermore, the concentrations of the quaternary ammonium salt aqueous dispersion, zinc oxide, silicone-based binder, and urethane-based binder in the treatment liquid were 9%, 3%, 3%, and 6%, respectively.

[0087] Two towels were randomly selected from a number of towels and immersed in this treatment solution. After removing the towels from the treatment solution, they were wrung out using a mangle to a wringing rate of 100%, and then air-dried and heat-treated at 120°C for 4 minutes. This gave two Control A towels.

[0088] Next, the towels were washed in accordance with the C4M method specified in JIS L 1930. Specifically, the towels were washed in wash water to which JAFET standard blend detergent (Textile Evaluation Technology Council) was added at a ratio of 1.33 g / L, and then hung to dry. As a result, two samples A were obtained.

[0089] The same procedure as above was carried out except that the proportions of the quaternary ammonium salt aqueous dispersion, zinc oxide, silicone-based binder, and urethane-based binder were changed as shown in Figure 6, and two each of Controls B to E and Samples B to E were obtained. Control B and Sample B are towels treated with a treatment liquid that does not contain zinc oxide. Control C and Sample C are towels treated with a treatment liquid that does not contain a quaternary ammonium salt aqueous dispersion and a urethane-based binder. Control D and Sample D are towels treated with a treatment liquid that does not contain a urethane-based binder. Control E and Sample E are towels treated with a treatment liquid that does not contain a silicone-based binder.

[0090] The antiviral performance of each of Controls A to E and Samples A to E was evaluated. Specifically, in accordance with the plaque measurement method specified in JIS L 1922, the antiviral activity value (Mv) was calculated for influenza A virus and the SARS-CoV-2 mutant strain (Omicron strain) based on the following formula. However, for the Omicron strain, only Control A and Sample A were evaluated. According to Appendix G of JIS L 1922, an Mv of 3.0 or greater can be judged as "sufficiently effective," and an Mv of 2.0 or greater but less than 3.0 can be judged as "effective." Mv = log(Va) - log(Vc), where log(Va) and log(Vc) are defined as follows: log(Va): Common logarithm of the virus infectivity (PFU / test piece) of the standard cotton fabric immediately after inoculation. log(Vc): Common logarithm of the virus infectivity (PFU / test piece) of the antiviral-treated product after standing for 2 hours.

[0091] The results are shown in Figure 6 along with the proportion of each component in the treatment solution. From Figure 6, it can be seen that both Control A and Sample A can be judged to be "sufficiently effective" against the SARS-CoV-2 mutant strain. Furthermore, it can be seen that Control A can be judged to be "sufficiently effective" and Sample A can be judged to be "effective" against influenza A virus.

[0092] In contrast, although controls B, D, and E could be judged to be "sufficiently effective" against influenza A virus, Mv was less than 1.0 for samples B, D, and E. This shows that by including both a silicone-based binder and a urethane-based binder in the treatment solution, antiviral performance can be maintained even after washing.

[0093] [Coloration Test] Test pieces of 1 g each were cut out from an untreated (unprocessed) towel that had not been immersed in a treatment solution, Controls A to E, and Samples A to E. These test pieces were immersed in an acetic acid solution at 50 to 100°C and adjusted to a pH of 3 to 4. In this state, a quaternary ammonium salt test paper was immersed in the acetic acid solution, and it was observed whether the quaternary ammonium salt test paper developed a color.

[0094] The results are also shown in Figure 6. Note that "Y" indicates that the quaternary ammonium salt test paper turned green or blue. "N" indicates that no coloration was observed. From Figure 6, it can be evaluated that the quaternary ammonium salt was retained in Sample A, which maintained its antiviral performance, while the quaternary ammonium salt was not retained in Samples B, D, and E. In this way, the presence or absence of coloration corresponds to whether or not the antiviral performance was maintained.

[0095] [Evaluation 1 of Antibacterial Performance] The antibacterial performance of each of Controls A to E and another one of Samples A to E was evaluated. Specifically, the antibacterial activity value A was calculated for Staphylococcus aureus, Moraxella, Escherichia coli, and Klebsiella pneumoniae based on the following formula in accordance with the bacterial liquid absorption method specified in JIS L 1902. According to Table F of JIS L 1902, when A is 3.0 or more, it can be determined to be "strongly effective," and when A is 2.0 or more but less than 3.0, it can be determined to be "effective." A = (log(Ct) - log(C0)) - (log(Tt) - log(T0)) Here, the definitions of log(Ct), log(C0), log(Tt), and log(T0) are as follows. log(Ct): Common logarithm of the number of viable bacteria on the standard cotton cloth after 18 to 24 hours of culture log(C0): Common logarithm of the number of viable bacteria on the standard cotton cloth immediately after inoculation log(Tt): Common logarithm of the number of viable bacteria on the test sample after 18 to 24 hours of culture log(T0): Common logarithm of the number of viable bacteria on the test sample immediately after inoculation

[0096] The results are also shown in Figure 6. From Figure 6, it can be determined that both Control A and Sample A are "strongly effective" against all of the above-mentioned bacteria.

[0097] In contrast, control B was not effective against E. coli. Sample B had an antibacterial effect against specific bacteria. On the other hand, control C and sample C can be judged to have a "strong effect" against all of the above bacteria. This shows that zinc oxide is essential for maintaining antibacterial performance, and that by including a silicone-based binder in the treatment liquid, antibacterial performance against various types of bacteria is maintained.

[0098] [Color Fading Test 1] Rectangular test pieces measuring 3.5 x 5.5 cm were cut from each of the untreated towels, Controls A to E, and Samples A to E. These test pieces were immersed in 25 mL of an iodine aqueous solution with an available iodine concentration of 0.05 to 1.00 mg / mL, and then a starch aqueous solution was added to the iodine aqueous solution and allowed to stand. The iodine aqueous solution exhibited a bluish-purple color. In this state, the iodine aqueous solution was visually observed to determine whether it had faded within 30 minutes of being left standing.

[0099] The results are also shown in Figure 6. Note that "Y" indicates that discoloration was observed in the iodine aqueous solution. "N" indicates that discoloration was not observed in the iodine aqueous solution. From Figure 6, it can be evaluated that zinc oxide is retained in Sample A, which maintains its antibacterial performance against all of the above-mentioned bacteria, while zinc oxide is not retained in Samples B, D, and E. In this way, the presence or absence of discoloration corresponds to whether or not antibacterial performance is maintained.

[0100] [Evaluation of antibacterial performance 2] A 30% mixture of zinc oxide and a silicone binder was applied to cotton (100%) that had been scoured and bleached in the usual way. After drying, the fabric was spun and steam-set at 98°C for 15 minutes. The fabric was then knitted to obtain a cotton-processed knit. As shown in Figure 7, the zinc oxide concentration was 6% and the silicone binder concentration was 3%.

[0101] The cotton-processed knit was immersed in an aqueous solution containing 1 g / L of the anionic surfactant Pitchlan L-160 (manufactured by Nicca Chemical Co., Ltd.) and heat-treated at 80°C for 20 minutes. Then, soaping and rinsing were performed to remove excess scouring agent and impurities. The cotton-processed knit after drying was designated Control F.

[0102] Another control F obtained in the same manner was immersed in a dyeing solution of 20 times its weight, heated from 30°C to 60°C over 15 minutes, and dyed by leaving it at 60°C for 40 minutes after adding 2 g / L of sodium carbonate. The dyed cotton-finished knit was washed in hot water at 50°C for 10 minutes and the water was drained off, this process being repeated twice. It was then soaped at 90°C for 10 minutes, neutralized with 0.5 g / L of citric acid, and the liquid was drained off, this process being repeated three more times. This resulted in a cotton-finished knit dyed beige. The cotton-finished knit after drying was designated as control G. The staining solution was a mixture of 0.0348% LEVAFIX RED CA, 0.0482% LEVAFIX Blue CA, 0.135% LEVAFIX Blue CA (all manufactured by Dyster), 0.5 g / L tripolyphosphate, and 20 g / L sodium sulfate.

[0103] Control F and Control G were washed 100 times in accordance with the JIS L 1930 C4M method and then line-dried to obtain Samples F and G. The washing liquid was water to which JAFET standard blend detergent (Textile Evaluation Technology Council) had been added so as to reach a concentration of 1.33 g / L.

[0104] For the above Controls F and G and Samples F and G, the antibacterial activity values ​​A for Staphylococcus aureus, Moraxella, Escherichia coli, and Klebsiella pneumoniae were calculated in accordance with the bacterial liquid absorption method specified in JIS L 1902. The results are also shown in Figure 7. From Figure 7, it can be determined that Controls F and G and Samples F and G are all "strongly effective" against all of the above bacteria.

[0105] When functional processing is applied to cotton, the binder resin used to support the antibacterial agent in the natural fiber generally inhibits the water absorption of the fiber itself. Furthermore, the functional groups of the natural fiber lose their chemical activity due to the binder resin, making them less likely to bond with the reactive groups of the dye. For these reasons, textile products made from yarn spun from functional cotton with antibacterial properties, etc., are recognized as being difficult to dye after processing. Furthermore, the functional cotton is sized and woven (knitted) after spinning. Subsequently, the functional cotton undergoes desizing, scouring, and post-dyeing processes, and is immersed in alkaline, high-temperature chemicals. As a result, the antibacterial properties of the functional cotton generally decline. However, by selecting the second particles 18 and binder resin as described above, functional cotton exhibiting sufficient antibacterial properties even after post-dyeing can be obtained, as shown in Figure 7.

[0106] [Color Fading Test 2] Rectangular test pieces measuring 3.5 x 5.5 cm were cut out from each of Controls F and G and Samples F and G. These test pieces were immersed in 25 mL of an iodine aqueous solution with an available iodine concentration of 0.05 to 1.00 mg / mL, and then a starch aqueous solution was added to the iodine aqueous solution and the solution was allowed to stand. The iodine aqueous solution exhibited a bluish-purple color. In this state, the iodine aqueous solution was visually observed to determine whether it had faded within 30 minutes of being allowed to stand.

[0107] The results are also shown in Figure 7. Note that "Y" indicates that discoloration was observed in the iodine aqueous solution. From Figure 7, it can be evaluated that zinc oxide was maintained in Controls F and G and Samples F and G. Thus, in this case as well, a relationship was obtained between the presence or absence of discoloration and whether or not antibacterial performance was maintained.

[0108] From the above results, it is possible to evaluate whether or not the antiviral activity is maintained by a color test using quaternary ammonium salt test paper, and it is also possible to evaluate whether or not the antibacterial activity is maintained by a color fading test using an iodine aqueous solution.

[0109] REFERENCE SIGNS LIST 10... Fiber material 12... Fiber body 14... Binder film 16... First particle 18... Second particle 20... Support particle 30... Woven fabric 32... Warp thread 34... Weft thread

Claims

1. A method for evaluating a fibrous material (10) including a fibrous body (12) containing at least one of cellulose fibers, animal fibers, and synthetic fibers by a color development test, the method comprising: immersing the fibrous material in an acetic acid solution; performing a color development test of dipping a quaternary ammonium salt test paper into the acetic acid solution to check whether the quaternary ammonium salt test paper develops color; and when the quaternary ammonium salt test paper develops color in the color development test, determining that first particles (16) containing a quaternary ammonium salt are retained on the surface of the fibrous body.

2. The method for evaluating a fibrous material according to claim 1, wherein the pH of the acetic acid solution is 4 or less.

3. The method for evaluating a fibrous material according to claim 1 or 2, wherein it is checked whether the quaternary ammonium salt test paper develops color within 15 seconds after dipping the quaternary ammonium salt test paper into the acetic acid solution.

4. A method for evaluating a fibrous material including a fibrous body containing at least one of cellulose fibers, animal fibers, and synthetic fibers by a fading test, the method comprising: immersing the fibrous material in an aqueous iodine solution; performing a fading test of checking whether the aqueous iodine solution that has turned blue-violet by an iodine-starch reaction fades; and when the aqueous iodine solution fades in the fading test, determining that second particles (18) composed of a metal oxide capable of reducing iodine are retained on the surface of the fibrous body.

5. The method for evaluating a fibrous material according to claim 4, wherein it is checked whether the aqueous iodine solution fades within less than 30 minutes after immersing the fibrous material in the aqueous iodine solution.

6. A method for evaluating a fibrous material including a fibrous body containing at least one of cellulose fibers, animal fibers, and synthetic fibers, the method comprising: a coloring test of immersing the fibrous material in an acetic acid solution and dipping a quaternary ammonium salt test paper into the acetic acid solution to check whether the quaternary ammonium salt test paper colors; and a fading test of immersing the fibrous material in an aqueous iodine solution and checking whether the aqueous iodine solution that has exhibited a bluish-violet color by an iodine-starch reaction fades, the coloring test and the fading test being performed in any order. When the quaternary ammonium salt test paper colors in the coloring test, it is determined that first particles containing a quaternary ammonium salt are retained on the surface of the fibrous body. When the aqueous iodine solution fades in the fading test, it is determined that second particles composed of a metal oxide capable of reducing iodine are retained on the surface of the fibrous body.

7. The method for evaluating a fibrous material according to claim 6, wherein the pH of the acetic acid solution is 4 or less.

8. The method for evaluating a fibrous material according to claim 6, wherein it is checked whether the quaternary ammonium salt test paper colors within 15 seconds after dipping the quaternary ammonium salt test paper into the acetic acid solution.

9. The method for evaluating a fibrous material according to any one of claims 6 to 8, wherein it is checked whether the aqueous iodine solution fades within less than 30 minutes after immersing the fibrous material in the aqueous iodine solution.

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