JP2020041233A - Anti-bacterial fiber - Google Patents

Abstract

To provide an anti-bacterial fiber excellent in washing durability, that has minimal effect on the human body such as skin irritation, and, in addition, that does not cause deterioration in consumption performance such as color fading over time.SOLUTION: Provided is a fiber obtained by graft polymerizing a polar vinyl monomer to a fiber, and in which the absorbance ratio B/A of the absorbance B of the absorption peak derived from alkali metal carboxylate to the absorbance A of the absorption peak derived from carboxylic acid according to infrared spectroscopy is 0.01 to 0.04, and in which, in an antibacterial evaluation using Staphylococcus aureus (yellow grape-shaped micrococcus) NBRC 12732 strain as a test strain based on a bacterial liquid absorption method and a pour plate culture method described in JIS L 1902 (2015), the antibacterial activity values of an unwashed treatment and a 10 times washed treatment in accordance with the washing method C4M of Annex F of JIS L 1930 (2014) are 2.2 to 6.5 in all cases.SELECTED DRAWING: None

Description

  The present invention is a modified fiber obtained by graft-polymerizing a polar vinyl monomer on the surface of clothing fibers represented by natural fibers, regenerated fibers, semi-synthetic fibers, and synthetic fibers under specific conditions. The present invention relates to an antibacterial fiber having excellent antibacterial performance.

  Conventionally, antibacterial fibers with excellent washing durability include surfactant-based, alcohol-based, phenol-based, biguanide-based, anilide-based, imidazole / thiazole-based, isothiazolone-based, nitrile-based, organic metal-based, and inorganic metal-based fibers. A variety of antibacterial agents have been proposed. In particular, antibacterial agents utilizing the antibacterial effect of quaternary ammonium cations, antibacterial agents using metal ions such as silver, copper and zinc, and antibacterial agents containing halogen atoms such as chlorhexidine gluconate are widely used. Have been.

  Usually, these antibacterial agents are formulated by a known method such as kneading into fibers, an exhaustion method, and a pad dry cure method. The antimicrobial agent component does not need to be uniformly dispersed in the fiber, and may be unevenly distributed on the fiber surface. However, it is desired that the antibacterial agent component has excellent general consumption performance such as washing durability.

  For example, Patent Document 1 proposes a method of applying a quaternary ammonium salt after stretching and drying the same during wet spinning of an acrylic fiber. According to this method, the antibacterial agent can be held on the fine irregularities on the fiber surface, but the antibacterial agent gradually drops off due to repeated washing, and for a long time, sufficient antibacterial performance can be secured. No.

  Patent Document 2 proposes a method of exhausting a fiber with a pyridine derivative exemplified by zinc pyrithione (zinc pyrithione, ZPT) and the like. According to this method, sufficient antibacterial properties can be obtained even with a relatively low concentration of antibacterial agent, but as a problem due to maintaining excellent performance, skin irritation is strong, and application to clothing applications Then it is necessary to consider the prescription amount enough.

  Further, Patent Document 3 proposes that an antibacterial fiber can be obtained by treating a cellulosic fiber with an organic acid such as malic acid or citric acid. However, this method is limited to cellulosic fibers excluding rayon, and cannot be expected to be applied to general-purpose synthetic fibers such as polyester and polyamide.

  Many antibacterial fibers carrying metal ions such as silver, copper, and zinc have also been proposed. For example, in the method of supporting silver ions as disclosed in Patent Documents 4 to 6, excellent antibacterial performance and bacteriostatic performance can be maintained, but the fiber itself is highly likely to change color over time due to oxidation or sulfurization, and is a fluorescent white dyed product And it is difficult to apply it to ultra-light colored products.

  On the other hand, as a method for modifying polyester fibers, Patent Document 7 proposes a polyester fiber having excellent hygroscopicity in which a vinyl monomer having hydrophilicity is introduced into the polyester fiber surface by graft polymerization at a graft ratio of 5 to 25%. I have. According to this method, a fabric excellent in wearing comfort and hygroscopicity can be obtained, but no method has been proposed which can provide antibacterial properties with washing durability without causing discoloration or deterioration in performance.

  Patent Document 8 proposes a method of imparting a radically polymerizable compound to a polyester fiber having an unsaturated dicarboxylic acid with high durability by a radiation graft polymerization method. According to this method, a fabric excellent in water absorption, moisture absorption, and antistatic properties can be obtained, but no method has been proposed yet that can provide antibacterial properties with washing durability.

  Further, Patent Document 9 discloses a woven fabric containing cellulose fibers graft-polymerized with a carboxylic acid-based vinyl monomer, which is derived from the content ratio of alkali metal and / or divalent metal and carboxylic acid and metal salt of carboxylic acid. The thing which improved the deodorizing property by optimizing the ratio of each light absorbency is proposed. However, in this method, although the deodorizing property is improved, the antibacterial property with the washing durability is not obtained because the aim is not to improve the antibacterial property.

Japanese Patent No. 2985690 Japanese Patent No. 4239284 Japanese Patent No. 6092510 JP 2002-235281 A JP 2004-169206 A JP-A-2004-190197 JP 2004-324008 A JP-A-6-128878 JP 2012-251265 A

  The present invention has been made in view of the state of the art, and an object of the present invention is to provide a fiber having excellent washing durability with respect to antibacterial properties. It is an object of the present invention to provide an antibacterial fiber which is small in amount and does not cause deterioration in consumption performance such as discoloration with time and has excellent washing durability.

  The inventor of the present invention has conducted intensive studies on fibers having antibacterial properties which are durable for washing in order to achieve the above-mentioned object. As a result, the absorbance A of the absorption peak derived from the alkali metal carboxylate relative to the absorbance A of the absorption peak derived from the carboxylic acid is shown. By making the absorbance ratio B / A in the specific range lower than that for the purpose of deodorization and graft polymerizing a polar vinyl monomer to the fiber, washing without causing defects for clothing They have found that durable antibacterial properties can be imparted to fibers, and have completed the present invention.

That is, the present invention has the following configurations (1) to (8).
(1) A fiber obtained by graft-polymerizing a polar vinyl monomer onto a fiber, wherein the absorbance B of the absorption peak derived from the alkali metal carboxylate to the absorbance B of the absorption peak derived from the carboxylic acid is determined by infrared spectroscopy. Based on the absorbance ratio B / A of 0.01 to 0.04, and the bacterial solution absorption method and the pour plate method described in JIS L 1902 (2015), Staphylococcus aureus (test strain) In the evaluation of antibacterial activity using Staphylococcus aureus) NBRC12732 strain, the antibacterial activity values after washing 10 times in accordance with JIS L 1930 (2014) Appendix F, washing method C4M, were 2.2 to 2.2. An antibacterial fiber characterized by being 6.5.
(2) The antibacterial fiber according to (1), wherein the polar vinyl monomer contains at least one selected from the group consisting of acrylic acid, methacrylic acid, and derivatives thereof.
(3) The antibacterial fiber according to (1) or (2), wherein the polymerization ratio of the polar vinyl monomer graft-polymerized to the fiber is 12 to 60% in terms of fiber weight ratio.
(4) The antibacterial fiber according to any one of (1) to (3), wherein the residual amount of the polar vinyl monomer in the fiber is less than 5 μg / g.
(5) The antibacterial fiber according to any one of (1) to (4), wherein sodium and / or potassium is contained as an alkali metal element contained in the fiber.
(6) The antibacterial fiber according to (5), wherein the content of the alkali metal element measured by inductively coupled plasma mass spectrometry (ICP-MS) is more than 1000 µg / g and 8000 µg / g or less.
(7) The antibacterial fiber according to any one of (1) to (6), wherein the pH of the extract of the fiber with water is not less than 3.0 and less than 8.0.
(8) In the antibacterial evaluation using Staphylococcus aureus (Staphylococcus aureus) NBRC 12732 strain as a test strain, the cells were not washed and washed 10 times according to the washing method C4M of JIS L 1930 (2014) Appendix F. The antibacterial fiber according to any one of (1) to (7), wherein the subsequent antibacterial activity values are 3.0 to 6.0.

  The antibacterial fiber of the present invention has an antibacterial property having excellent washing durability, has less skin irritation, and can be used in a wide variety of fields, regardless of whether it is for clothing or materials. Further, since the antibacterial fiber of the present invention does not contain metals such as silver and copper, there is an advantage that there is no fear of causing discoloration and deterioration in performance due to oxidation and sulfide.

  The antimicrobial fiber of the present invention will be described in detail below. As raw material fibers, polyester, polyamide, polyolefin, polyacrylonitrile, polyvinyl chloride, vinylon, polyvinylidene chloride, synthetic fibers such as polylactic acid, natural fibers such as cotton, hemp, animal hair, silk, rayon, polynosic, cupra, Regenerated fibers such as lyocell and modal; and semi-synthetic fibers such as cellulose acetate and promix. In particular, general-purpose fibers for clothing such as cotton, rayon, lyocell, and polyester are preferably used.

  The cross-sectional shape when synthetic fibers, semi-synthetic fibers, or regenerated fibers are used as the raw material fibers is not particularly limited, and known cross-sectional shapes can be used. If necessary, it is also possible to knead and use a functional processing agent such as a matting agent, a pigment, an antioxidant, and an ultraviolet absorber. Also, the single yarn fineness is not particularly limited.

  When the content of the alkali metal element in the antibacterial fiber of the present invention is quantitatively evaluated by using inductively coupled plasma mass spectrometry (ICP-MS), the content is more than 1000 μg / g, not more than 8000 μg / g, preferably more than 2000 μg / g, The range is 7000 μg / g or less, more preferably 3000 μg / g or more and 6500 μg / g or less. If the content of the alkali metal element exceeds the above range, good moisture absorption properties can be obtained, but the dough pH increases, and as a result, a stable high antibacterial property is obtained without being in an acidic region where the carboxylate anion is stabilized. It is difficult. In addition, below the above range, when used in clothing, the irritation when directly touching the skin is strong and the antibacterial properties are also reduced.

  Examples of the alkali metal element include sodium, potassium, and lithium, which are typical elements belonging to Group 1 excluding hydrogen in the periodic table, and particularly preferably include sodium and / or potassium. When the alkali metal element contained in the fiber of the present invention is sodium, the antibacterial fiber of the present invention is subjected to quantitative evaluation by inductively coupled plasma mass spectrometry (ICP-MS) for the same reason as the preferable alkali metal element content. It is preferable that the sodium content is more than 2000 μg / g and 8000 μg / g or less.

  The antimicrobial fiber of the present invention has an absorbance ratio B / A of 0, which is calculated from the absorbance A of the absorption peak derived from the alkali metal carboxylate with respect to the absorbance A of the absorption peak derived from the carboxylic acid by infrared spectroscopy. 0.01 to 0.04, preferably 0.013 to 0.037. In a range where the absorbance ratio B / A exceeds the above-mentioned range, that is, in a system in which the ratio of the alkali metal carboxylate is large, although the system has a high hygroscopic property, the gelation is remarkable and the mechanical strength at the time of moistening cannot be maintained. In addition, if the amount is less than the above range, particularly when graft polymerization is performed on hydrophobic fibers, the resulting fibers have poor hygroscopicity, which is not preferable from the viewpoints of texture, comfort, and wearing feeling when the fibers are used.

  The antibacterial fiber of the present invention is based on the bacterial solution absorption method and the pour plate culture method described in JIS L 1902 (2015), and has the antibacterial activity using Staphylococcus aureus (Staphylococcus aureus) NBRC 12732 as a test strain. In the evaluation, the antibacterial activity value after washing 10 times according to the washing method C4M of Annex F of JIS L 1930 (2014) Appendix F was 2.2 to 6.5, and further 3.0 to 6 And even 4.0 to 6.0 can be achieved.

  The antibacterial fiber of the present invention has an antibacterial effect not only on the antibacterial effect against Gram-positive bacteria represented by Staphylococcus aureus (Staphylococcus aureus) and pneumococcus, but also on Gram-like bacteria such as Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa. The effect can be expected for negative bacteria. The reason why the fiber obtained by polymerizing a polar vinyl monomer as in the present invention exhibits antibacterial properties is that the carboxylate anion exerts an antibacterial action on bacteria in a state where it is controlled in a certain fabric pH range. it is conceivable that.

  The antibacterial activity in the present invention was evaluated based on the bacterial solution absorption method and the pour plate culture method described in JIS L 1902 (2015), using Staphylococcus aureus (Staphylococcus aureus) NBRC12732 as a test strain. The strain is also specified in the SEK Mark Textile Product Certification Standard (Document Control No. JEC301, revised on April 1, 2018) specified by the Textile Evaluation Technology Council of Japan.

  The washing method, especially the standard for home washing, generally used the 103 method described in Appendix 1 of the 1995 edition of JIS L0217. However, when the 2014 edition of JIS L0001 and the 2014 edition of JIS L1930 were issued, A washing evaluation method based on a washing method C4M specified in JIS L1930 Appendix F is being generalized as a method having a washing action force similar to the 103 method.

  The antibacterial fiber of the present invention has an antibacterial activity value after washing 10 times by the above-mentioned washing method C4M method and an antibacterial activity value without washing in each case of 2.2 to 6.5, and more preferably 3.0 to 3.0. 6.0, and even 4.0 to 6.0 can be achieved. If the antibacterial activity value is less than the above range, excellent antibacterial performance cannot be exhibited, and if the antibacterial activity value exceeds the above range, on the contrary, it not only affects the resident bacteria on the skin surface, but the skin irritation is too strong However, there is a high possibility that skin disorders will occur.

  The antimicrobial fiber of the present invention is a fiber obtained by graft-polymerizing a polar vinyl monomer to the fiber, and the polar vinyl monomer may include at least one selected from the group consisting of acrylic acid, methacrylic acid, and derivatives thereof. preferable. In imparting antibacterial properties to textile products, antibacterial agents containing a primary amide, a secondary amide, a tertiary amide, a quaternary ammonium cation and the like have been widely used, and excellent antibacterial properties have been used. It is already known to have. The antimicrobial fiber of the present invention is characterized by having antimicrobial properties even without the above-mentioned conventional amide, ammonium cation, etc., but does not prevent the use of conventionally known antimicrobial agents. Further, the polar vinyl monomer does not need to have a single composition, and may be copolymerized with a plurality of types of polar vinyl monomers as necessary, or may be copolymerized with another reactive monomer.

  The antibacterial fiber of the present invention comprises a residual amount of the polar vinyl monomer in the fiber (that is, a polar vinyl monomer that remains unreacted during graft polymerization, and a polar vinyl monomer depolymerized by hydrolysis or the like after graft polymerization, and a modified product thereof). Is preferably less than 5 μg / g based on the total weight of the fiber. The residual amount of the polar vinyl monomer is obtained by ultrasonically extracting a fiber sample with ethanol and evaluating the obtained ethanol solution by a gas chromatograph mass spectrometer (GCMS). Is synonymous with less than the lower limit of detection. From the viewpoint of the skin irritation of the obtained antibacterial fiber, the smaller the residual amount of the polar vinyl monomer, the better.

  As a measure for reducing the residual amount of the polar vinyl monomer in the fiber, it is obvious that the charged monomer should not be excessively charged, and high-temperature drainage after graft polymerization, repeated hot water washing, and overflow water washing. Combination, reducing the amount of residual monomer in the dough. After the graft polymerization, unreacted monomers and their decomposed products, auxiliaries such as dispersants and initiators and their decomposed products remain in the treatment solution, and more specifically, the bath temperature is 70 to 85 ° C. , Preferably 75 to 80 ° C., it is possible to reduce the residual amount of the polar vinyl monomer in the fiber.

  In addition, with respect to repeated hot water washing, washing is repeatedly performed at a bath temperature of 80 to 100 ° C., and the monomers in the fibers are discharged into the bath. Similarly, the bath temperature is in the range of 70 to 85 ° C., preferably 75 to 80 ° C. It is advisable to drain at a high temperature in the range. The number of repetitions is desirably two or more times. After repeated hot water washing, overflow water washing at a bath temperature of 40 to 60 ° C. can further reduce the residual amount. In order to promote the discharge of the polar vinyl monomer, an anionic or nonionic surfactant may be used in combination.

  When a polar vinyl monomer is graft-polymerized to a fiber, a polymerization initiator is used. As the polymerization initiator, azobisisobutyronitrile (AIBN) which is an azo compound and benzoyl peroxide (BPO) which is an organic peroxide are used. ), A dual initiator (redox initiator) based on a combination of an oxidizing agent and a reducing agent, such as hydrogen peroxide and iron (II) salt, and a persulfate and sodium bisulfite.

  The method of graft polymerization of polar vinyl monomer to fibers includes the method of batch processing short fibers using a high-pressure container such as an Overmeyer dyeing machine, the method of soft-winding spun yarn and filaments, and the method of high-pressure Examples of the method include a method of performing batch processing using a container, a method of forming a sheet such as a woven fabric, a knitted fabric, or a non-woven fabric, and performing a continuous processing using a high-pressure pad steamer or the like, or a method of performing a batch processing using a zicker-dyeing machine or the like. In particular, a method in which short fibers are batch-processed using a high-pressure container such as an Over-Meier dyeing machine in the subsequent spinning step is preferable from the viewpoint of imparting further functionality and texture by mixing with other fibers.

  The polymerization ratio (graft ratio) of the polar vinyl monomer graft-polymerized to the fiber is preferably in the range of 12 to 60%, more preferably 15 to 45% in terms of fiber weight ratio. Although the antibacterial performance can be exhibited even when the polymerization ratio is less than the above range, it may be insufficient from the viewpoint of washing durability. On the other hand, when the polymerization ratio exceeds the above range, there is a possibility that a decrease in fiber strength and elongation, a decrease in various color fastness, and curing of the antibacterial fiber may occur.

  The polar vinyl monomer preferably contains at least one selected from the group consisting of acrylic acid, methacrylic acid, and derivatives thereof. That is, a vinyl monomer having a carboxy group is preferable. However, the polar vinyl monomer does not need to be a monomer having a single composition, and the copolymerization amount may be appropriately adjusted according to the performance to be obtained, such as a combination of methacrylic acid and acrylic acid, a combination of methacrylic acid and vinyl chloride, and a combination of methacrylic acid and styrene. Adjust it. Of the polar vinyl monomers, methacrylic acid is particularly preferably used.

  When a polar vinyl monomer is graft-polymerized to a fiber, when the polar vinyl monomer is a carboxy group, the pH of the reaction solution is preferably adjusted to 2.8 to 4.0. More preferably, it is 3.0 to 3.5. When the pH is out of the pH range, the efficiency of the graft polymerization reaction decreases, and it becomes difficult to obtain a desired graft polymerization rate. Immediately after the graft polymerization, most of the carboxy groups introduced into the fiber are in the form of an acid type (—COOH), and are strongly acidic. If used as it is, even if the antibacterial property is high, the burden on the human body increases, so it is preferable to perform a neutralization operation. In the neutralization, a part of hydrogen of the carboxy group can be replaced with a hydroxyl group or an alkali metal salt using water or an alkaline compound. A more preferred neutralization method is to neutralize the grafted fiber using water and / or hot water without using an alkaline compound.

  Incidentally, the fiber neutralization treatment may be performed immediately after the graft polymerization process, or may be performed at any stage up to the final product such as yarn, woven or knitted fabric, nonwoven fabric, or clothing, and the final product is sold. It suffices that the pH is in the proper extraction pH range before going to the consumption stage.

  However, by converting a part of the carboxy group into an alkali metal salt, functions other than antibacterial properties such as deodorizing property, moisture absorbing property, pH control property, etc. can be obtained. It may be replaced with an alkali metal salt. As the alkali compound to be used, an alkali metal compound which is soluble in water and whose aqueous solution exhibits alkalinity is preferably used. Examples of the alkali metal compound include hydroxides, carbonates, and phosphates of alkali metals. Specific examples thereof include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, potassium carbonate, lithium carbonate, and phosphorus phosphate. Sodium acid, potassium phosphate, lithium phosphate and the like can be mentioned.

  It is preferable that the pH of the extract (hydrogen ion index) of the yarn, cotton, or dough obtained by the above-described grafting and neutralization treatment with water is 3.0 or more and less than 8.0. Considering that the carboxylate anion has an antibacterial property against bacteria, it is desirable to control the carboxylate anion in an acidic region where the carboxylate anion is more stabilized in order to obtain a stable and high antibacterial property. Therefore, as described above, it is preferable to control the pH in an acidic region of 3.0 or more and less than 8.0, preferably 4.0 or more and less than 7.0, and more preferably 4.5 or more and less than 6.5. Good. When the pH of the extract is below the above range, irritation to the skin is increased as described above. When the pH of the extract exceeds the above range, not only is there a concern that discoloration such as yellowing of the light-colored dyed product is likely to occur, but also the antibacterial property of the fiber is likely to be reduced.

  The alkali metal element content contained in the antimicrobial fiber of the present invention can be controlled by a treatment with an alkali metal compound after graft polymerization of a polar vinyl monomer onto the fiber. The alkali metal element content can be controlled by the concentration of the aqueous solution of the alkali metal compound, the concentration of the alkali metal compound used with respect to the fiber, the bath ratio (weight ratio between the fiber and the treatment liquid), the treatment temperature, the treatment time, and the like.

  The antibacterial fiber of the present invention can be obtained by performing graft polymerization on the fiber with a vinyl monomer having a carboxy group, and then neutralizing a part of the carboxy group. The obtained antibacterial fiber can exhibit sufficient antibacterial properties by setting the absorbance ratio of the absorbance of the alkali metal carboxylate / the absorbance of the carboxylic acid as low as 0.010 to 0.040. More preferably, it is 0.014 to 0.037.

  The antimicrobial fiber of the present invention is used alone or as appropriate as a woven or knitted material by a known method such as mixing and blending with other fibers, blending, and weaving, as well as being used alone or as appropriate with other fibers to form a card web. After that, the nonwoven fabric may be entangled by a method such as needle punching or thermal bonding, or may be a laminate formed by combining several obtained nonwoven fabrics. Further, using the obtained two-dimensional sheet material, it is also possible to use a higher-order processing such as resin coating, film lamination, bonding and the like. Needless to say, they can be used alone or as appropriate in combination with other fibers to be used as padding cotton for futons, cushions, chairs and the like.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples, and can be appropriately modified and implemented without departing from the gist shown in the text and the examples. Needless to say. The performance evaluation in Examples and Comparative Examples of the present invention is based on the following.

(Graft polymerization rate)
The absolute dry weight of the raw fibers before the graft polymerization was Wa, the absolute dry weight of the fibers after the graft polymerization was dried in a dryer at 105 ° C for 3 hours or more, and cooled in a desiccator under a 20 ° C environment for 20 minutes or more. Is Wb, and the graft polymerization rate (G) was calculated based on the following equation.
G (% by mass) = 100 × (Wb−Wa) / Wa

(Quantification of residual monomer amount)
After precisely weighing 0.3 g of the sample, immersing it in 15 ml of ethyl alcohol and performing ultrasonic extraction for 30 minutes, the obtained ethyl alcohol solution was subjected to the following conditions using a gas chromatograph mass spectrometer according to the following conditions. Identification and quantification were performed.
(Gas chromatograph mass spectrometry conditions (GC-MS))
・ Apparatus: Model QP-2010 manufactured by Shimadzu Corporation ・ Column: Stabllwax (length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm)
・ Inlet temperature: 240 ° C
-Column linear velocity: 40 cm / sec

(Antibacterial evaluation)
A) Quantitative tests were carried out by the bacteria solution absorption method and the pour plate culture method specified in JIS L1902 “Test method and antibacterial effect of textile products” in the 2015 edition. The test strain was evaluated using Staphylococcus aureus (Staphylococcus aureus / Staphylococcus aureus) NBRC 12732 strain, which was supplied by the National Institute of Technology and Evaluation Biotechnology Center.

(Measurement of metal concentration in fiber)
The measurement of the metal concentration in the fiber is performed by performing a primary screening of the contained metal by a fluorescent X-ray analysis method to obtain an approximate value of the metal concentration, and then, by an inductively coupled plasma mass spectrometry method, an alkali metal (Na, K, The precise concentration of Li) was determined.

The metal concentration in the fiber was measured by X-ray fluorescence analysis. Based on the concentration of a known metal (titanium atom as titanium dioxide) present in the fiber, an approximate value of the concentration was determined from the intensity of the fluorescent X-ray irradiation of the detected element.
[X-ray fluorescence analysis (XRF)]
-Equipment: JSX-1000S type manufactured by JEOL Ltd.-Atmosphere: vacuum-Voltage: 50 kV
-Measurement range: sodium to uranium (excluding rhodium)

(Measurement of metal concentration in fiber)
(Preparation of measurement sample)
Using a mixed solution of nitric acid (1 + 1) and hydrogen peroxide (volume ratio of nitric acid (1 + 1): hydrogen peroxide 4: 1) as a solvent, microwave decomposition method (pressurized acid decomposition method in a closed container) at 200 ° C. ) To decompose the fiber sample to obtain a solution sample.
In the quantitative test, the element content (μg / g) of the element detected by the primary screening was determined based on the following inductively coupled plasma mass spectrometry (ICP-MS method), and the content of the alkali metal salt was examined.

[Inductively coupled plasma mass spectrometry conditions (ICP-MS)]
-Equipment: 7700x type manufactured by Agilent Technologies-Carrier gas flow rate: 1.07 L / min-Plasma gas flow rate: 15 L / min-Auxiliary gas flow rate: 0.9 L / min

[Infrared spectroscopy (FT-IR)]
(Preparation of test sample)
After the fiber sample was thoroughly unraveled, it was molded into a film by applying pressure, and the infrared spectrum was measured by a microscopic transmission method.

(How to determine the absorbance ratio)
Tangential line connecting the first valley near the lower wavelength side of the absorption peak around the first valley near the wavelength 1545 cm ^-1 on the high wavelength side of the absorption peak near a wavelength of 1709 cm ^-1 and a baseline, wavelength 1709 cm around ^-1 The height A from the baseline at the peak top is determined as the absorbance at a wavelength of 1711 cm ^-1 (absorption derived from carboxylic acid). Next, the height B from the baseline at the peak top near the wavelength of 1545 cm ⁻¹ is defined as the absorbance at the wavelength of 1558 cm ⁻¹ (absorption derived from the alkali metal carboxylate). As the alkali metal carboxylate, a sodium salt, a potassium salt, a lithium salt, and the like are supposed, but even if they are mixed, the absorbance peaks do not branch, and have a broad peak shape. It is sufficient to measure the height of the peak top. If a clear absorption peak is not observed, the height of the baseline at the position of wavelength 1711 cm ^-1 or 1545 cm ^-1 is taken as the absorbance of the absorption, and the absorbance ratio is calculated by the following formula.
Absorbance ratio (B / A) = absorbance of alkali metal carboxylate / absorbance of carboxylic acid

[Infrared spectroscopy (FT-IR) conditions]
-Apparatus: Nicolet iN10 type manufactured by Thermo Fisher Scientific Inc.-Measurement wavelength: 4000 to 500 cm ^-1
・ Detector: MCT detector ・ Resolution: 8cm ^-1
・ Beam splitter: KBr (potassium bromide)

(PH of fiber extract with water)
It was measured under the conditions of JIS L1096: 2010 extract pH (8.37) method A (JIS method). However, when the measurement sample is a fiber or a yarn, the sample is weighed to 5.0 g ± 0.1 g and subjected to the extraction test as it is.

(Washing test)
The washing treatment was performed according to the C4M method specified in Appendix F of the 2014 edition of JIS L1930 "Testing method for home laundry of textile products". As the standard detergent, 1.33 g / L specified in Table 1 of 9.4 was used by using a JAFET standard combination detergent. At the time of washing, the grafted fiber is put into a nylon net, and a load cloth (as defined in Appendix H) based on each raw material fiber is combined, and the weight of the object to be washed is about 2 kg (washing bath ratio 1:20). Laundry and dehydration treatments were implemented. After the dehydration treatment, the fibers were taken out of the nylon net, the fibers were loosened by hand, lightly removed with blotter paper, dried under standard conditions for 24 hours or more, and subjected to antibacterial evaluation.

(Skin patch test)
Using the fiber subjected to the surface graft polymerization, a 48-hour obstruction sticking test was performed. For a subject (23 healthy Japanese men and women), a specimen (surface graft polymerized fiber) and a control substance (physiological saline, Otsuka Pharmaceutical Co., Otsuka Pharmaceutical Co., Ltd.) Distilled water and white vaseline manufactured by Nikko Rica Co., Ltd. were respectively contained in absorbent cotton) and occluded and applied for 48 hours without air contact.

After 48 hours, the attached sample was peeled off, and the skin condition immediately after peeling off the pasted sample (after 48 hours from pasting) and 72 hours after pasting (after 24 hours after peeling off the sample pasted after 48 hours) Was visually judged by a dermatologist to evaluate skin irritation.
The configuration of the patch test unit used for the obstruction sticking test is as follows.
・ Finn Chamber (EPITEST, Finland)
・ Scanor Tape (NORGESPLASTER, Norway)

In the method of calculating the skin irritation index, a score is given to the higher response after 48 hours or 72 hours, and the value obtained by dividing the total score of each test substance by the number of subjects is expressed as a percentage.
The criteria are as shown in Table 1, and the skin irritation index is derived from the following equation.
Skin irritation index = total score / number of subjects x 100

  From the obtained skin irritation index, safety is evaluated by “classification of cosmetics by skin irritation index” shown in Table 2. The basis for the safety judgment is based on “Cosmetics and Safety” (Tetsuro Sugai) described in Journal of the Japan Cosmetic Science Association 19 (extra edition), pp. 49-56.

(Examples 1 to 8) and (Comparative Examples 1 to 4)
As raw material fibers used, Lyocell staple fiber (1.3 dtex, 38 mm cut product) manufactured by Lentung, rayon (Modal) staple fiber (1.1 dtex, 39 mm cut product) manufactured by Lentung, China Petrochemical Industry Group Using three types of polyester semi-dal staple fiber (fineness: 6.6 decitex, 64 mm cut), packed into a Hisaka Seisakusho Overmeyer dyeing machine at a bath ratio of 1:10 and scouring at a bath temperature of 80 ° C Was carried out. After repeating drainage, hot water washing, and water washing, chemicals other than the pH adjuster shown in Table 1 were charged, and a graft ratio to the fiber surface was set at a bath ratio of 1:10 and a treatment temperature × time shown in Table 3. Advanced.

  After draining, a hot water washing treatment was performed at 70 ° C. × 10 minutes. By changing the number of repetitions of the hot water washing treatment, the pH of the fiber extract was controlled so as to be as shown in Table 1. In the case of neutralization using a pH adjuster (alkali compound), the treatment is performed in the middle of repeated hot water washing, and the hot water washing is further repeated. The conditions for using the pH adjuster are a bath ratio of 1:10, a predetermined concentration of the PH adjuster, and a condition of 60 ° C. × 30 minutes. After draining, 4 g / L of spinning oil (Honol MGR manufactured by Takemoto Yushi Co., Ltd.) was added, and a bath liquid circulation treatment was performed at a bath ratio of 1:10 at 80 ° C. for 10 minutes. After drainage, dehydration drying and fiber opening were performed to obtain an antibacterial fiber (staple fiber) composed of each raw material fiber. The performance obtained was as shown in Table 4.

  The antibacterial fiber of the present invention is an antibacterial fiber excellent in washing durability that has little effect on the human body such as skin irritation and does not cause deterioration in consumption performance such as discoloration with time, and has innerwear, sports and uniforms. It is suitable for use in clothing such as working, and for living materials such as curtains, sheets, and wallpapers.

Claims (8)

  A fiber obtained by graft-polymerizing a polar vinyl monomer onto a fiber, the ratio of the absorbance B of the absorption peak B derived from the alkali metal carboxylate to the absorbance A of the absorption peak derived from the carboxylic acid being measured by infrared spectroscopy / A is 0.01 to 0.04, and based on the bacterial solution absorption method and the pour plate culture method described in JIS L 1902 (2015), Staphylococcus aureus (Staphylococcus aureus) is used as a test strain. ) In the evaluation of antibacterial activity using NBRC 12732 strain, the antibacterial activity values after washing 10 times in non-washing and after washing 10 times in accordance with washing method C4M in Appendix F of JIS L 1930 (2014) are all 2.2 to 6.5. An antimicrobial fiber, characterized in that:   The antibacterial fiber according to claim 1, wherein the polar vinyl monomer contains at least one selected from the group consisting of acrylic acid, methacrylic acid, and derivatives thereof.   The antibacterial fiber according to claim 1 or 2, wherein the polymerization ratio of the polar vinyl monomer graft-polymerized to the fiber is 12 to 60% in terms of fiber weight ratio.   The antibacterial fiber according to any one of claims 1 to 3, wherein the residual amount of the polar vinyl monomer in the fiber is less than 5 µg / g.   The antibacterial fiber according to any one of claims 1 to 4, wherein sodium and / or potassium are contained as the alkali metal element contained in the fiber.   The antibacterial fiber according to claim 5, wherein the content of the alkali metal element measured by inductively coupled plasma mass spectrometry (ICP-MS) is more than 1000 µg / g and 8000 µg / g or less.   The antimicrobial fiber according to any one of claims 1 to 6, wherein the pH of the extract of the fiber with water is 3.0 or more and less than 8.0.   In the evaluation of antibacterial activity using Staphylococcus aureus (Staphylococcus aureus) NBRC 12732 strain as a test strain, the antibacterial activity after non-washing and after 10 times washing treatment according to washing method C4M of Appendix F of JIS L 1930 (2014) Appendix F. The antibacterial fiber according to any one of claims 1 to 7, wherein the activity value is 3.0 to 6.0.