JP2021055213A - Antimicrobial composite fiber - Google Patents

Abstract

To provide an antimicrobial composite fiber that exhibits excellent antimicrobial properties and inhibits discoloration even after alkaline treatment.SOLUTION: An antimicrobial composite fiber is a composite fiber having a polyamide resin in a sheath and a polyurethane resin in a core, which contains an inorganic antimicrobial agent containing at least silver as an antimicrobial metallic component, and which satisfies (a) and (b). (a) The content of the inorganic antimicrobial agent in the polyamide resin is 0.1 mass% or more and 1.2 mass% or less. (b) The content of the silver component in the polyamide resin is 20 ppm or more and 600 ppm or less.SELECTED DRAWING: None

Description

The present invention relates to a polyamide-based composite fiber having antibacterial properties.

Polyamide fibers are widely used for clothing such as carpets, towels, underwear, socks, and stockings. When used for stockings, a yarn in which a polyamide fiber is covered with a polyurethane fiber of a core yarn or a composite fiber in which a polyamide component and a polyurethane component are eccentrically arranged in the same filament is used. In particular, composite fibers exhibit excellent crimpability and transparency.
Further, there is an increasing demand for fibers having antibacterial properties for these uses, and a method of adhering a compound having antibacterial properties to fibers by post-processing has been adopted.
However, the method of imparting antibacterial properties by post-processing has a problem in durability because it is easily removed by washing or the like. As a method for improving washing durability, a fiber containing an inorganic antibacterial agent such as a porous body carrying silver or copper ions in the fiber has been proposed.
Patent Document 1 proposes atypical polyester fibers in which silver ions are supported on zeolite as an antibacterial metal component and an inorganic antibacterial agent having an average particle size of 5 μm or less is contained. Further, it has been shown that by reducing the particle size of the inorganic antibacterial agent, the yarn-making stability is improved and high-quality fibers in which the occurrence of yarn breakage and fluff are suppressed can be obtained. Patent Document 2 proposes a polyamide fiber using a polyamide resin composition in which silver fine particles protected by a nitrogen-containing polymer are supported. It is shown that the antibacterial metal fine particles are protected by the nitrogen-containing polymer, so that the antibacterial property is good even after the dyeing process under acidic conditions.
However, when silver ions are used as the antibacterial metal component, there arises a problem that the silver ions are oxidized by the influence of alkali treatment or oxygen in the air in the subsequent process, and the fibers are discolored.
Therefore, Patent Document 3 proposes a polyester fiber containing an inorganic antibacterial agent composed of a phosphate carrying silver ions and titanium dioxide as an antibacterial metal component. It has been shown that by concealing the discoloration of silver with titanium dioxide, the discoloration of the fabric due to alkali treatment or the like can be suppressed.

Japanese Unexamined Patent Publication No. 2004-3600091 Japanese Unexamined Patent Publication No. 2016-065195 JP-A-2002-309445

However, although it is possible to impart antibacterial properties to polyamide composite fibers by a method containing a silver-based antibacterial agent as in Patent Documents 1 to 3, discoloration is likely to occur and it is difficult to suppress it.
That is, in Patent Document 1, discoloration of the antibacterial agent occurs when exposed to alkali. In Patent Document 2, the polyamide resin is discolored yellow when it is supported on the surface of the polyamide resin. In Patent Document 3, the discoloration of the inorganic antibacterial agent can be concealed by containing titanium dioxide, but it is difficult to conceal the discoloration of the polyamide resin.
Therefore, an object of the present invention is to obtain an antibacterial composite fiber having excellent antibacterial properties and suppressing discoloration in alkaline treatment.

The gist of the present invention is a composite fiber in which a polyamide resin containing an inorganic antibacterial agent containing at least silver as an antibacterial metal component is arranged in a sheath portion and a polyurethane resin is arranged in a core portion (a). ) And (b) are antibacterial composite fibers.
(A) Content of inorganic antibacterial agent in polyamide resin is 0.1% by mass or more and 1.2% by mass or less (b) Silver component content in polyamide resin is 20ppm or more and 600ppm or less Further, inorganic antibacterial agent The average particle size (D ₅₀ ) of the agent is preferably 0.1 μm or more and 5.0 μm or less. Further, it is preferable that the antibacterial activity value by the bacterial solution absorption method is 2.2 or more. Further, the color difference (ΔE) before and after the alkali treatment is preferably 2.0 or less. Further, it is preferable that the core portion is eccentrically arranged in the cross section of the fiber, and 85% or more and 99% or less of the core portion is covered with the sheath portion.

According to the antibacterial composite fiber of the present invention, it is excellent in antibacterial property and yarn-making stability, and discoloration can be suppressed by alkaline treatment, so that it can be suitably used for clothing applications such as underwear, socks, and stockings.

FIG. 1 shows an example of the cross-sectional shape of the composite fiber of the present invention.

In the antibacterial composite fiber of the present invention, the sheath portion is composed of a polyamide resin and the core portion is composed of a polyurethane resin.

The polyamide resin in the present invention is not particularly limited, and examples thereof include single or copolymers such as nylon 6, nylon 66, nylon 610, nylon 10, nylon 11, and nylon 12.

The polyurethane resin in the present invention is not particularly limited, and examples thereof include single or copolymers such as polyester-based polyurethane, polycarbonate-based polyurethane, polycarbonate-based polyurethane, and polyether-based polyurethane.

To the above-mentioned polyamide resin and polyurethane resin, for example, an ultraviolet absorber, an electrostatic agent, a pigment, titanium oxide and the like may be added as long as they do not inhibit the antibacterial property, and a deodorant and a fungicide may be added. Etc. may be given.

The antibacterial composite fiber of the present invention contains an inorganic antibacterial agent. The inorganic antibacterial agent in the present invention contains at least silver as an antibacterial metal component, and the content of the inorganic antibacterial agent in the polyamide resin is 0.1% by mass or more and 1.2% by mass or less. If the content of the inorganic antibacterial agent is less than 0.1% by mass, it becomes difficult to obtain sufficient antibacterial properties. If it exceeds 1.2% by mass, yarn breakage, fluff, etc. are likely to occur, and it becomes difficult to stably produce yarn. Preferably, it is 0.3% by mass or more and 1.1% by mass or less. More preferably, it is 0.6% by mass or more and 1.1% by mass or less.

The antibacterial composite fiber of the present invention has a silver component content of 20 ppm or more and 600 ppm in the polyamide resin. If the silver component content is less than 20 ppm, it becomes difficult to obtain sufficient antibacterial properties. If it exceeds 600 ppm, the antibacterial performance is improved, but the discoloration after the alkali treatment becomes large. It is preferably 100 ppm or more and 600 ppm or less, more preferably 300 ppm or more and 550 ppm or less.

The silver component content in the polyamide resin of the present invention refers to a value measured using an ICP emission spectrometer CIROS CCD manufactured by AMETEK.

_{The average particle size (D 50} ) of the inorganic antibacterial agent of the present invention is preferably 0.1 μm or more and 5.0 μm or less. If the average particle size (D ₅₀ ) is less than 0.1 μm, when it is added to the polyamide resin, it aggregates and becomes coarse, and yarn breakage, fluff, etc. are likely to occur, and it becomes difficult to stably produce yarn. Further, the same problem occurs when the average particle size (D _{50) exceeds 5.0 μm.} It is preferably 0.5 μm or more and 3.0 μm or less, and more preferably 0.5 μm or more and 2.0 μm or less.

The inorganic antibacterial agent of the present invention preferably contains P, Mg, Al, and Si. Since it contains P, Mg, Al, and Si, it becomes easy to suppress discoloration of the polyamide resin. The preferable contents of each element are 20% by mass or more and 30% by mass or less for P, 5% by mass or more and 15% by mass or less for Mg, 1% by mass or more and 5% by mass or less for Al, and 1% by mass or more for Si. 5, 5% by mass or less.

In the antibacterial composite fiber of the present invention, an inorganic antibacterial agent may be added to the polyurethane resin, but the surface exposure of the core portion is low, and it is difficult to obtain the effect favorably.

It is preferable that the antibacterial composite fiber of the present invention contains the above-mentioned inorganic antibacterial agent and has an antibacterial activity value of 2.2 or more calculated from the viable cell count after culturing for 18 hours. This index is an index for evaluating the antibacterial property, and if the antibacterial activity value is less than 2.2, it is difficult to obtain the desired antibacterial property.

The method for calculating the antibacterial activity value of the present invention was a bacterial solution absorption method based on JIS L1902. As a test bacterium, Staphylococcus aureus (NBRC12732) was used, and the antibacterial activity value was calculated by the following method.
Antibacterial activity value: log (Ct / Co) -log (Tt / To)
Ct: Viable cell count (average value) of 3 samples after 18-hour culture of standard cloth
Co: Viable cell count (average value) of 3 samples immediately after inoculation of test bacteria on standard cloth
Tt: Viable cell count (average value) of 3 samples after 18-hour culture of test samples
To: Viable cell count (average value) of 3 samples immediately after inoculation of the test bacteria of the test sample
However, it is assumed that the test establishment conditions (Ct / Co ≧ 1.0, Tt / To ≧ 1.0) are satisfied.

By containing the inorganic antibacterial agent as described above, the antibacterial composite fiber of the present invention can prevent discoloration before and after the alkaline treatment, and the color difference (ΔE) before and after the treatment is 2.0 or less. It is preferable to have. When ΔE exceeds 2.0, it becomes dull. In addition, poor color development is likely to occur in the dyeing process. More preferably, it is 1.5 or less.

The above alkaline treatment is a scouring step, and is an alkaline solution at 80 ° C. to which a soaping agent (“Tripole” (0.2 g / L) manufactured by Daiichi Kogyo Co., Ltd.) and sodium carbonate (2 g / L) is added, and has antibacterial properties. The tubular knitting of the composite fiber is subjected to a dipping treatment for 30 minutes.

The cross-sectional shape of the antibacterial composite fiber of the present invention is not particularly limited and can be appropriately set according to the required characteristics and application, but a round cross section is preferable from the viewpoint of suppressing discoloration. If the cross section is irregular, the color tends to be easily discolored as the surface area increases, and it is difficult to obtain the effect favorably.

The fiber cross section of the antibacterial composite fiber of the present invention is shown in FIG. In the cross section of the fiber, the core portion a has a core-sheath structure arranged eccentrically, and it is preferable that 85% or more and 99% or less of the outermost circumference of the core portion a is covered with the sheath portion b. If the coverage of the core portion is less than 85%, the adhesiveness between the core portion and the sheath portion becomes insufficient, and the core portion and the sheath portion are likely to be peeled off due to wear or the like. When the coverage of the core portion exceeds 99%, the crimping property is lowered. More preferably, the coverage is 90% or more and 97% or less. Such a fiber cross section has a crimping property and can have sufficient antibacterial properties while suppressing discoloration.

In the antibacterial composite fiber of the present invention, the total fineness is not particularly limited and can be appropriately set according to the required characteristics and the application. The filament count is also not particularly limited. From the viewpoint of silk reeling stability, the total fineness is preferably 10 dtex or more and 50 dtex or less. It is more preferably 15 dtex or more and 45 dtex or less, and further preferably 18 dtex or more and 40 dtex or less.

In the antibacterial composite fiber of the present invention, the strength is not particularly limited and can be appropriately set according to the required characteristics and application, but from the viewpoint of the knitting and weaving process, 2.0 cN / dtex or more, 7 It is preferably 0.0 cN / dtex or less. More preferably, it is 2.5 cN / dtex or more and 7.0 cN / dtex or less.

In the antibacterial composite fiber of the present invention, the elongation is not particularly limited and can be appropriately set according to the required characteristics and application, but from the viewpoint of post-processing, 30% or more and 80% or less. preferable. More preferably, it is 40% or more and 70% or less.

The antibacterial composite fiber of the present invention can be used alone or in combination with other polyamide stretchable crimped yarns, polyurethane-based covering yarns, and other fibers such as synthetic yarns, mixed knitting, and mixed weaving.

Next, a preferable example of the method for producing the antibacterial composite fiber of the present invention will be described.

For the antibacterial composite fiber of the present invention, a mixed resin obtained by mixing the above-mentioned polyamide resin with the above-mentioned inorganic antibacterial agent and the above-mentioned polyurethane resin are prepared.

As a method of mixing the inorganic antibacterial agent with the polyamide, a method of mixing the inorganic antibacterial agent at the time of polymerization of the polyamide resin or a method of kneading the inorganic antibacterial agent with the polyamide resin in advance using a twin-screw extruder to form a master chip. However, it is not limited to these.
When a master chip is used, the mixed resin of the polyamide resin and the master chip and the polyurethane resin are separately melted, discharged from the spinneret so as to have the above-mentioned fiber cross-sectional shape, cooled, and then stretched. , The antibacterial composite fiber of the present invention can be obtained.

The spinning temperature is preferably 225 ° C. or higher and 260 ° C. or lower, more preferably 230 ° C. or higher and 250 ° C. or lower, from the viewpoint of heat resistance and spinnability of the polyamide resin and polyurethane resin. The spinning speed is preferably 400 m / min or more and 1000 m / min or less, and more preferably 500 m / min or more and 800 m / min or less.

The stretching temperature is preferably 20 ° C. or higher and 60 ° C. or lower, more preferably 25 ° C. or higher and 50 ° C. or lower, from the viewpoint of silk reeling stability. The draw ratio is preferably about 3.2 times or more and 3.7 times or less from the viewpoint of stable production.

In this way, the antibacterial composite fiber of the present invention having good antibacterial properties and yarn-forming stability can be obtained.

Hereinafter, examples of the present invention will be specifically described, but the following examples exemplify the present invention and do not limit the present invention. The methods for measuring and evaluating various physical properties were as follows.

(1) Evaluation of yarn-making stability The evaluation was made according to the following criteria based on the average number of yarn breaks per 24 hours when the fiber was produced.
◯: When the number of thread breaks is less than 1 ×: When the number of thread breaks is 1 or more

(2) Measurement of strength and elongation of fiber A tensile test was conducted using Autograph AGS manufactured by Shimadzu Corporation in accordance with JIS L1013, and the fiber broke under the conditions of measurement length: 200 mm and tensile speed: 200 mm / min. The breaking strength and the breaking elongation were measured 5 times each, and the average value was calculated and used as the strength and elongation of the fiber.

(3) Evaluation of antibacterial activity The above antibacterial activity value was calculated according to JIS L1902. The calculated antibacterial activity value was evaluated according to the following criteria.
⊚: Antibacterial activity value is 5.0 or more ○: Antibacterial activity value is 2.2 or more and less than 5.0 ×: Antibacterial activity value is less than 2.2

(4) Discoloration evaluation The color difference (ΔE) was measured using a colorimetric color difference meter (“Datacoror 800” manufactured by Datacoror) before and after the above-mentioned alkali treatment of the tubular knitted fabric made of the obtained antibacterial composite fiber. The measured ΔE was evaluated according to the following criteria.
◯: When ΔE is 2.0 or less ×: When ΔE exceeds 2.0

[Example 1]
A masterbatch was prepared by mixing 20% by mass of an inorganic antibacterial agent having an average particle size (D ₅₀ ) of 2.0 μm with nylon 6, and the content of the inorganic antibacterial agent in the sheath was 0.4% by mass. Nylon 6 and the masterbatch were mixed so that the silver component content was 200 ppm. A mixed resin of nylon 6 masterbatch is used for the sheath, and polycarbonate polyurethane is used for the core. The core sheath is spun from the mouthpiece at 233 ° C so as to form an eccentric core sheath as shown in FIG. 1, and the core sheath is 600 m / min. The undrawn yarn in a ratio of 1: 1 was wound up. Next, the obtained undrawn yarn was drawn at a drawing temperature of room temperature and a drawing ratio of 3.5 times, wound at a speed of 450 m / min, and 89% of the outermost circumference of the core was covered with a sheath, 19dtex. An antibacterial composite fiber of / 2f was obtained. The silk reeling stability was good, and the obtained antibacterial composite fiber showed a good antibacterial activity value of 4.9 and ΔE of 0.66. The results obtained are shown in Table 1.

[Example 2]
An antibacterial composite fiber was produced in the same manner as in Example 1 except that the content of the inorganic antibacterial agent in the sheath was 0.7% by mass and the silver component content was 350 ppm. The silk reeling stability was good, and the obtained antibacterial composite fiber showed a good antibacterial activity value of 5.9 and ΔE of 0.65. The results obtained are shown in Table 1.

[Example 3]
An antibacterial composite fiber was produced in the same manner as in Example 1 except that the content of the inorganic antibacterial agent in the sheath was 1.0% by mass and the silver component content was 500 ppm. The silk reeling stability was good, and the obtained antibacterial composite fiber showed a good antibacterial activity value of 5.9 and ΔE of 0.71. The results obtained are shown in Table 1.

[Comparative Example 1]
An antibacterial composite fiber was produced in the same manner as in Example 1 except that the content of the inorganic antibacterial agent in the sheath was 1.5% by mass and the silver component content was 750 ppm. As for the stability of silk reeling, yarn breakage occurred frequently, and antibacterial composite fibers could not be collected. The results obtained are shown in Table 1.
[Comparative Example 2]
An antibacterial composite fiber was produced in the same manner as in Example 2 except that the silver component content in the sheath was 700 ppm. The silk reeling stability was good, and the antibacterial activity value of the obtained antibacterial composite fiber was 5.9, but ΔE was significantly discolored to 11.53. The results obtained are shown in Table 1.

[Comparative Example 3]
It was prepared in the same manner as in Example 1 except that an inorganic antibacterial agent was not mixed in the sheath. The silk reeling stability was good, and the ΔE was also good at 0.23, but the antibacterial activity value was 1.3 and the antibacterial property was not good. The results obtained are shown in Table 1.

The antibacterial composite fibers obtained in Examples 1 to 3 had excellent crimping properties, good silk-reeling stability, excellent antibacterial properties, and discoloration was suppressed even in alkaline treatment. On the other hand, in Comparative Examples 1 to 3, either the silk reeling stability or the antibacterial property was poor, or discoloration was confirmed after the alkali treatment.

The antibacterial composite fiber of the present invention has good yarn-making stability and antibacterial properties, and discoloration after alkali treatment is suppressed, so that it can be suitably used for clothing applications such as underwear and stockings.

a core b sheath

Claims (5)

Composite fibers in which a polyamide resin containing an inorganic antibacterial agent containing at least silver as an antibacterial metal component is arranged in a sheath and a polyurethane resin is arranged in a core, and (a) and (b) are It is an antibacterial composite fiber that satisfies.
(A) Content of inorganic antibacterial agent in polyamide resin is 0.1% by mass or more and 1.2% by mass or less (b) Silver component content in polyamide resin is 20ppm or more and 600ppm or less The antibacterial composite fiber according to claim 1, wherein the average particle size (D ₅₀ ) of the inorganic antibacterial agent is 0.1 μm or more and 5.0 μm or less. The antibacterial composite fiber according to claim 1 or 2, wherein the antibacterial activity value by the bacterial solution absorption method is 2.2 or more. The antibacterial composite fiber according to any one of claims 1 to 3, wherein the color difference (ΔE) before and after the alkaline treatment is 2.0 or less. The antibacterial composite fiber according to any one of claims 1 to 4, wherein the core portion is eccentrically arranged in the fiber cross section, and 85% or more and 99% or less of the core portion is covered with the sheath portion. ..

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