JP2000248465A - Antibacterial mixed yarn - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antibacterial mixed yarn having a sufficient water- absorbing property and a water holding property, and also excellent in bacteriostatic and antibacterial effect by imparting a hydrophilic surfactant to a mixed yarn of a polylactic acidbased fiber with a fiber having a prescribed water content of more than a specific value. SOLUTION: This antibacterial mixed yarn having >=2.2 bacteriostatic activity value is obtained by imparting >=100 ppm hydrophilic surfactant surface-treating agent to a mixed yarn containing a polylactic acid-based polymer consisting of any of the polymer selected from a group of a poly(D-lactic acid), poly(L- lactic acid), D-lactic acid/L-lactic acid copolymer, D-lactic acid/a hydroxycarboxylic acid copolymer and D, L-lactic acid/the hydroxycarboxylic acid copolymer or a blended material of them and having >=80 deg.C melting point, with 30-70 wt.% fiber having >=5% prescribed water content such as cotton.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed yarn having antibacterial properties.

[0002]

2. Description of the Related Art A method of imparting antibacterial properties to a material has hitherto been used today. For example, there is a method in which a fiber material, a fiber cloth, a sheet or the like is subjected to a surface treatment with an antibacterial substance. However, although this method can impart antibacterial performance, there is a problem that the durability of the antibacterial performance is poor. As a method for solving this problem, there is a method of mixing and kneading an active antibacterial substance in a manufacturing process of a fiber material such as nylon or polyester. However, although this method shows a certain antibacterial performance, it is costly. In general, many antibacterial agents themselves have a certain degree of toxicity, which poses a safety problem.

[0003]

DISCLOSURE OF THE INVENTION In view of the above problems, the present inventors have studied an antibacterial agent which is inexpensive and safe. Hitherto, lactic acid has been used as a food preservative for improving the shelf life of foods, and it is known that lactic acid has a bacteriostatic and antifungal action. But,
There is no clear report that fibers and films made of polylactic acid-based polymer, which is a dehydration-condensation polymer of lactic acid, have antibacterial properties, much less antibacterial properties in relation to polylactic acid polymer composition. There is no. We have:
In the process of forming into fibers, the potential bacteriostatic
As a result of various studies on the relationship between the polylactic acid-based polymer and the antibacterial property in order to exhibit a fungicidal action, remarkable antibacterial activity is recognized in a specific composition range of the constituent components of the polylactic acid-based polymer. The inventors have found that the present invention has been achieved.

[0004]

The present invention relates to a mixed yarn comprising a polylactic acid-based fiber and a fiber having an official moisture content of 5% or more, wherein the mixed yarn is provided with a hydrophilic surfactant, An antibacterial mixed yarn characterized in that the bacteriostatic activity value is 2.2 or more.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The polylactic acid-based polymer constituting the polylactic acid-based fiber used in the present invention is a thermoplastic aliphatic polyester, and a polymer having poly (α-hydroxy acid) as a main repeating unit is used. No. Specifically, poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, a copolymer of D-lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid and hydroxycarboxylic acid Copolymers with carboxylic acids, DL-lactic acid and hydroxycarboxylic acids, and the like,
Among these polymers, those having a melting point of 80 ° C. or higher are preferred. Here, examples of the hydroxycarboxylic acid in the case of a copolymer of lactic acid and hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxycaprylic acid, and the like.

[0006] Such a polylactic acid-based polymer has a number average molecular weight of about 20,000 or more, preferably 40,000 or more, in view of the spinning properties and the obtained yarn properties. As for the upper limit of the number average molecular weight, it is sufficient that melt spinning can be performed, and it is sufficient that the number average molecular weight be about 150,000.

[0007] If necessary, other additives such as matting agents, pigments, nucleating agents and the like may be added to the polylactic acid-based polymer within a range that does not impair the effects of the present invention. good.

[0008] The cross-sectional shape of the polylactic acid-based fiber may be any shape such as an elliptical shape, a diamond shape, a triangular shape, a rectangular shape, a polygonal shape, a T-shaped shape, a well-shaped shape, etc., in addition to a normal round shape. Can be selected as appropriate. Further, it may have a hollow cross-sectional shape having a hollow portion.

The polylactic acid-based fibers may be of a single-phase form composed of one kind of polylactic acid-based polymer alone or of a composite form composed of two or more kinds of polylactic acid-based polymers. Examples of the composite form include a parallel composite form, a multilayer composite form, a core-in-sheath composite form, a split composite form, and a split multilobal composite form, and may be appropriately selected according to the use and the like.

[0010] In the polylactic acid-based fiber constituting the mixed yarn of the present invention, the larger the fiber surface area is, the larger the contact area with the bacterium is, so that the bacteriostatic action can be exerted. Even when used for applications requiring performance, fibers having a large surface area are excellent in decomposability. Therefore, it is preferable to use a cross-sectional shape such as a hollow cross section, a modified cross section, or a split composite cross section.

The degree of crystallinity of the polylactic acid fiber is 10 to 40.
%. By setting the crystallinity of the fiber within the above range, the heat shrinkage of the fiber is suppressed to be low, and the fiber has practical mechanical strength. Crystallinity in the above range, by performing a heat treatment or stretching, and, for the polylactic acid-based polymer, for example, talc, boron nitride, calcium carbonate, magnesium carbonate, a crystal nucleating agent such as titanium oxide This is achieved by adding. The addition of a crystal nucleating agent promotes fiber crystallization, improves the mechanical strength and heat resistance of the obtained mixed yarn, and furthermore, between the spun yarns in the melt spinning and cooling steps during production. This is preferable because fusion (blocking) can be prevented. The amount of the nucleating agent added is in the range of 0.1 to 3.0% by weight,
More preferably, the content is in the range of 0.2 to 2.0% by weight.

The single fiber fineness of the polylactic acid-based fiber may be appropriately selected, but is preferably 0.5 denier or more. If the single yarn fineness is less than 0.5 denier, the production amount tends to decrease, and when the number of spinnerets is increased to improve the production amount, the spinning process becomes unstable. Further, the upper limit of the single yarn fineness is not particularly limited. From the viewpoint of production by a method of solidifying the fibers with general cooling air, about 50 denier is preferable. If it exceeds 50 denier, take-off tends to be difficult due to insufficient cooling of the melt-spun yarn, and if the number of holes in the spinneret is reduced to promote cooling of the yarn, the production volume will decrease. I do.

The mixed yarn of the present invention contains fibers having a water absorption of not less than the official moisture content of 5%. The fibers having the official moisture content of not less than 5% include natural fibers such as cotton, hemp,
Wool, silk, etc. can be used. Viscose rayon, copper ammonia rayon obtained from pulp, and lyocell, which is a solvent-spun rayon, can also be used as the recycled fiber. Furthermore, even synthetic fibers containing polyetheresteramide,
Those containing a modified polyalkylene oxide can also be used. Further, as the fiber having an official moisture content of 5% or more, two or more kinds of the above-mentioned fibers may be used.

Fibers having an official moisture content of 5% or more contribute to the manifestation of the bacteriostatic and antibacterial properties of the polylactic acid-based fibers described below, since they have excellent water absorption. Further, by mixing fibers having an official moisture regain of 5% or more with the mixed yarn of the present invention, sufficient water absorption and water retention can be imparted to the mixed yarn. A cloth made of such a mixed yarn is suitably used for applications such as clothing having excellent sweat absorption properties and a wiper having excellent moisture wiping properties.

Natural fibers and regenerated fibers having an official moisture content of 5% or more have the property of being degraded by microorganisms in nature in the same manner as polylactic acid-based short fibers, and are therefore suitable for applications requiring biodegradability. Can be used.

The form of the polylactic acid-based fiber and the fiber having an official moisture content of 5% or more, which constitute the present invention, may be a short fiber or a long fiber, and is appropriately selected according to the purpose.

The mixed yarn of the present invention comprises a polylactic acid-based fiber and a fiber having an official moisture content of 5% or more. The mixed fiber is prepared by a known blending method or blending method. It is what it was.

The mixing ratio (weight ratio) between the polylactic acid-based fiber and the fiber having an official moisture content of 5% or more of the mixed yarn of the present invention is 70%.
/ 30 to 30/70. When the proportion of the polylactic acid-based fiber is less than 30% by weight, the antibacterial effect aimed at by the present invention tends not to be obtained, and when it exceeds 70% by weight, the water absorption of the cross-knitted fabric tends to be poor.

The mixed yarn of the present invention is provided with a hydrophilic surfactant. Examples of the hydrophilic surfactant include an anionic surfactant, a cationic surfactant, and a nonionic surfactant. , Amphoteric surfactants and the like,
These may be used alone or in combination. The surfactant may be sprayed onto the mixed yarn in the form of an aqueous solution or aqueous dispersion adjusted to a predetermined concentration (for example, about 1 to 1.5% by weight). Before mixing the constituent fibers (in the fiber production step or the like), the polylactic acid-based fibers and / or fibers having an official moisture content of 5% or more may be sprayed. In addition, when these fibers are short fibers, when sprayed onto a cotton blend web in the cotton blending step, the fibers to which the surfactant has been imparted are reduced in entanglement when the fiber is opened by a fiber opening device such as a card machine. It is preferred.

The surfactant provided to the mixed yarn is 1
It is preferably at least 00 ppm. If it is less than 100 ppm, the antibacterial effect of the mixed yarn tends to be hardly exerted.

Since the polylactic acid-based polymer is hydrophobic, the fiber made of the polylactic acid-based polymer is also hydrophobic. Such a hydrophobic polylactic acid-based fiber, even if the material itself has antibacterial properties, that is, lactic acid, lactide and other oligolactic acid in the polylactic acid-based polymer constituting the polylactic acid-based fiber described below Does not exhibit an antibacterial effect that actively suppresses the growth of bacteria. It is presumed that the addition of the hydrophilic surfactant makes the surface of the polylactic acid-based fiber hydrophilic, so that it can be brought into contact with bacteria and the growth of bacteria can be suppressed. Furthermore, the mixed yarn of the present invention is in a state where fibers having an official moisture content of 5% or more and polylactic acid-based fibers are mixed, and the fibers are adjacent to each other.
Since the polylactic acid-based fiber is in contact with the moisture contained in the fiber having an official moisture content of 5% or more, it is presumed that the polylactic acid-based fiber is likely to be in contact with the bacteria and its propagation can be suppressed.

It is presumed that such an antibacterial effect is exerted because a small amount of lactic acid, lactide and other oligolactic acid are contained in the polylactic acid-based polymer constituting the polylactic acid-based fiber. You. The polylactic acid-based polymer constituting the polylactic acid-based fiber preferably contains 0.01 to 1.0% by weight of lactic acid, lactide and other oligolactic acid. If the content of lactic acid, lactide and other oligolactic acid is less than 0.01% by weight, the effect of antibacterial performance is weakened, while if it exceeds 1.0% by weight, it is hydrolyzed by moisture such as moisture in the air even at room temperature even at room temperature. Progresses, resulting in a tendency to lack long-term storage stability.

In the present invention, in order for the amounts of lactic acid, lactide and other oligolactic acids contained in the polylactic acid-based polymer constituting the polylactic acid-based fiber to fall within the above range,
Adjusting the reaction conditions during the polymerization process, or
After the polymerization is completed, the pressure is reduced in a molten state to remove excess lactide, oligolactic acid and the like.

The mixed yarn of the present invention has a bacteriostatic activity value of 2.2 or more according to a unified test method (a test method for antibacterial effect approved by the Textile Sanitation Processing Council). The bacteriostatic activity value is defined as B (cells / ml), which is obtained by inoculating a standard sample and a target sample with a certain number of test bacteria and culturing the standard sample for a certain period of time.
After culturing for a certain period of time, the viable cell count of the target sample was determined as C (cells / cells).
ml) and logB-logC. If the bacteriostatic activity value is less than 2.2, it cannot be said that the proliferation of bacteria can be suppressed.

[0025]

The present invention will be described below in detail with reference to examples. Note that the present invention is not limited to only these examples. In the examples, each property value was obtained as follows. The evaluation of the antibacterial property, that is, the bacteriostatic activity value was determined by the method described above. (1) Melting point (° C.): The temperature at which the extreme value of the melting endothermic curve obtained by using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer at a heating rate of 20 ° C./min is determined as the melting point. (° C.).

(2) Melt flow rate (hereinafter referred to as MFR)
That. ) (G / 10 min): The melt discharge amount at 210 ° C. under a load of 2160 g was measured according to the method described in ASTM D1238.

(3) Antibacterial performance: The antibacterial activity was evaluated by measuring the bacteriostatic activity value by a unified test method (an antibacterial effect test method approved by the Textile Sanitary Processing Council). In the evaluation, Staphylococcus a
ureus ATCC 6538P (Staphylococcus aureus) was used. That is, 0.4 ml of a sterilized sample placed in a vial is inoculated as uniformly as possible with 0.2 ml of a bacterial solution having a viable cell count adjusted to 1 ± 0.3 × 10 ^5, and cultured at 37 ° C. for 18 hours. Twenty ml of physiological saline containing 0.2% of Twin 80 is added, and the mixture is stirred to wash out the bacteria. A 10-fold dilution series was prepared, diluted with a nutrient agar medium, cultured at 37 ° C. for 24 hours or more, the number of colonies was counted, and the number of viable bacteria was determined.

For the calculation of the bacteriostatic activity value, the above test was carried out for each of the standard sample and the test sample, and the bacteriostatic activity value was determined from the following equation. In addition, a nylon standard white cloth was used as a standard sample. Bacteriostatic activity = logB-logC B: Number of bacteria recovered after 18 hours of cultivation of standard sample C: Number of bacteria recovered after cultivation of test sample for 18 hours

Example 1 In order to produce a polylactic acid-based fiber, the optical purity was 98.8.
%, Melting point 170 ° C., MFR 25 g / 10 min.
The lactic acid resin is melted, the spinning temperature is 220 ° C., and the single hole discharge amount is 0.
Melt spinning was performed from a spinneret under a condition of 31 g / min. Next, the spun yarn was cooled by a cooling device, a spinning oil was applied, and the yarn was wound at a take-up speed of 800 m / min. Next, the obtained undrawn yarn is combined into a tow by drawing tow having a drawn tow fineness of 300,000 denier, using a known drawing machine having a different peripheral speed, at a drawing temperature of 120 ° C. and a draw ratio of 2.51.
After the stretching, the crimping was performed with a crimper, and 0.3% by weight of a finishing oil containing 20% by weight of polyethylene glycol monooleate having a molecular weight of 600 was provided. Thereafter, the tow was dried, and then dried. , 51mm
To obtain 1.5 denier polylactic acid-based short fibers. The monofilament strength of the obtained polylactic acid-based short fibers is 3.
The dry heat shrinkage under an atmosphere of 9 g / d and 120 ° C. for 15 minutes was 4.2%.

As the fiber having an official moisture content of 5% or more, bleached cotton having an average fineness of 1.5 denier and an average fiber length of 24 mm was prepared.

Then, the above-mentioned polylactic acid-based short fiber and 50% by weight of the above-mentioned polylactic acid-based short fiber are mixed and weighed so as to be 50% by weight. Got a sliver. This sliver is 3
This doubling was performed and passed through the first drawing machine. Further, eight of the obtained slivers were doubled and passed through the finishing drawing machine, and then two of the obtained slivers were doubled and passed through the roving machine. The obtained sliver was spun with a ring spinning machine to obtain a spun yarn having a twist of 19 turns / inch and a 40th count. The spun yarn had a strength of 2.8 g / d and an elongation of 33%.

Example 2 The mixing ratio of polylactic acid fiber and cotton fiber was 30/70.
(% By weight) to obtain a mixed yarn of the present invention in the same manner as in Example 1.

Example 3 The mixing ratio of polylactic acid fiber and cotton fiber was 70/30.
(% By weight) to obtain a mixed yarn of the present invention in the same manner as in Example 1.

Using the mixed yarns obtained in Examples 1 to 3, knitting was performed with a tubular knitting machine (manufactured by Koike Seisakusho) having 260 needles. The antibacterial performance of the obtained tubular knitted fabric was evaluated, and the results are shown in Table 1.

[0035]

[Table 1]

As is clear from Table 1, it was confirmed that all the fabrics comprising the mixed yarns of Examples 1 to 3 had bacteriostatic and antibacterial properties.

[0037]

According to the present invention, a hydrophilic yarn is added to a mixed yarn comprising a polylactic acid-based fiber and a fiber having an official moisture content of 5% or more. It is considered that the surface of the polylactic acid-based fiber becomes hydrophilic by the addition of the lactic acid-based fiber, thereby making it possible to come into contact with the bacterium and exhibit the bacteriostatic and antibacterial effect of suppressing the breeding of the bacterium. Further, since the mixed yarn of the present invention contains fibers having an official moisture content of 5% or more, it is likely to contain moisture in the air, and such fibers are in contact with the polylactic acid-based fibers. This makes the polylactic acid-based fiber more easily contact with bacteria. Therefore, fibers having an official moisture content of 5% or more contribute to the polylactic acid-based fibers exhibiting a bacteriostatic and antibacterial effect, and impart good moisture absorption and water absorption to the mixed yarn itself.

Further, the antibacterial mixed yarn of the present invention is extremely safe for the human body because the polylactic acid-based polymer exhibits antibacterial properties.

By using the mixed yarn of the present invention to produce textile products such as knitted fabrics, braids, strings, etc., various packaging materials such as foods, wallpaper, various filters, draining bags such as sinks, table cloths, and foot wipes. It can exhibit bacteriostatic and antibacterial properties in various fields such as daily necessities and living related materials such as mats and towels, agricultural and horticultural materials, medical and hygiene materials, and clothing.

Claims (4)

[Claims] 1. A mixed yarn comprising a polylactic acid-based fiber and a fiber having an official moisture content of 5% or more, wherein the mixed yarn is provided with a hydrophilic surfactant and has a bacteriostatic activity value of 2.2. An antibacterial mixed yarn characterized by the above. 2. The mixed yarn has a hydrophilic surfactant of 100 p.
2. The antibacterial mixed yarn according to claim 1, wherein the mixed yarn is provided with pm or more. 3. The polylactic acid-based fiber is poly (D-lactic acid),
Poly (L-lactic acid), copolymer of D-lactic acid and L-lactic acid, D-lactic acid
It is a copolymer of lactic acid and hydroxycarboxylic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, any polymer selected from DL-lactic acid and hydroxycarboxylic acid, or a blend thereof. The antibacterial mixed yarn according to claim 1 or 2, wherein 4. Short fibers having an official moisture regain of 5% or more are used
The antibacterial mixed yarn according to any one of claims 1 to 3, wherein the mixed yarn contains 70% by weight.