JP2021134431A - Antibacterial resin fiber - Google Patents

Abstract

To provide fine fibers (fiber diameter 20 μm or less) showing an excellent antibacterial performance without using antibacterial agents while among antibacterial fibers, fibers using antibacterial agents involve problems of antibacterial sustainability on a long term and discoloration and fibers prepared by using only one polyacetal resin having antibacterial performance are difficult to produce fine fibers and are limited in use.SOLUTION: The present inventors melt-spin and stretch a resin composition of a polyacetal resin (POM) 50 to 90 wt%, a polybutyl succinate resin (PBS) or a similar structural resin of PBS or a polylactic acid resin having a melt flow rate (MFR) of 4 to 30 g/10 minutes 10 to 45 wt%, and a carbodiimide resin 0 to 5 wt%, whereby they have found that antibacterial fibers having a fiber diameter 0.5 to 20 μm and excellent antibacterial property can be produced to come to complete the present invention.SELECTED DRAWING: None

Description

The present invention relates to an antibacterial fiber utilizing a composition consisting of a polyacetal resin and a specific polybutylsuccinate (PBS) resin or a polylactic acid (PLA) resin and a carbodiimide compound without using an antibacterial agent.

Synthetic resin fibers are used as important products not only in clothing but also in various fields. Many of the products require antibacterial properties. However, polyester fibers, polyamide fibers, polyolefin fibers, acrylic fibers, polyurethane fibers and the like, which are widely used as conventional fibers, do not have antibacterial properties, and therefore various techniques for imparting antibacterial properties have been proposed. Patent Document 1, Patent Document 2, and the like disclose techniques for attaching an antibacterial agent to fibers via a binder resin. As another method, a method of kneading an antibacterial agent into a resin and the like are also disclosed in Patent Documents 3 and 4. Many of the antibacterial agents use silver ions, and those supported on inorganic compounds such as apatite, glass, zeolite, and clay compounds have been proposed. Although such a method is effective at the initial stage, it has a problem that it is lost due to abrasion or washing, and the effect is lost at an early stage. Further, it has a drawback such as discoloration due to a treatment process after spinning and a change with time.

Many resins do not have antibacterial properties, and in order to make them antibacterial fibers, it is necessary to adopt the above-mentioned method, but only polyacetal resin has antibacterial properties, and water is used as an injection-molded product or an extrusion-molded product. It is usefully used in surrounding applications. However, polyacetal resins have been considered difficult to use as fibers because of their excellent crystallinity, high crystallization rate, and high crystallinity. In recent years, studies on using polyacetal resin as a fiber have begun to be actively conducted. The fibrosis technology of polyacetal resin is disclosed in Patent Document 5, Patent Document 6, Patent Document 7, and the like.

Further, Patent Document 8 discloses that the fiber is used for the purpose of utilizing the bactericidal and antibacterial properties of the polyacetal resin. However, as described above, the polyacetal resin has a drawback that it is difficult to stretch because the crystallization rate is high and the crystallinity is high, and therefore it is difficult to thin the line. Actually, antibacterial fibers are used after being processed into non-woven fabrics, knitted fabrics, woven fabrics, webs, etc., but in order to efficiently collect various bacteria and extremely small dust in the air, the fiber diameter is 20 μm or less, preferably 10 μm or less. , More preferably, it must be 5 μm or less, and it is extremely difficult to make this thin line with a polyacetal resin.

Japanese Unexamined Patent Publication No. 11-279952 Japanese Unexamined Patent Publication No. 10-325075 Japanese Unexamined Patent Publication No. 7-238421 Japanese Unexamined Patent Publication No. 7-3527 Japanese Unexamined Patent Publication No. 1-272821 Japanese Unexamined Patent Publication No. 8-144128 Japanese Unexamined Patent Publication No. 11-293523 WO2016 / 147998A1

Among antibacterial fibers, fibers using antibacterial agents have problems of long-term antibacterial persistence and discoloration. On the other hand, fibers using polyacetal resin, which has the only antibacterial performance, are difficult to thin and their applications are limited. Fine wire fibers (fiber diameter 20 μm or less) having excellent antibacterial performance without using an antibacterial agent are strongly desired.

The present inventors have a polyacetal resin of 50 to 90 wt% and a melt flow rate (MFR) of 4 to 30 g / 10 minutes of a polybutyl succinate resin (PBS) or a resin having a similar structure to PBS or a polylactic acid resin of 10 to 45 wt%, a carbodiimide compound. A filter produced from a resin composition of 0 to 5 wt%, which is a single-layer fiber or a multi-layer fiber and has a fiber diameter of 0.5 to 20 μm, has extremely excellent antibacterial properties and high drawability. , Knitted fabrics, textiles, webs, etc. have been found to be easily processed, and the present invention has been completed.

According to the production method of the present inventors, a fiber having a fiber diameter of 20 to 100 μm is melt-spun using a normal melt spinning apparatus, and the fiber diameter is reduced to 0.1 to 20 μm by stretching the fiber in one or multiple stages. Can be processed. It is necessary to make the fiber diameter of the filter finer for collecting submicron dust and bacteria in the air, but it is costly to process the diameter of the die hole to 100 μm or less for the production of such fine fiber. In the first place, troubles such as discoloration and blockage due to dust occur. Moreover, the production efficiency is extremely inferior with a die having a small fiber diameter. On the other hand, the polyacetal resin alloy fiber according to the present invention, which has high stretchability, can produce ultrafine fibers having extremely high production efficiency with a normal melt spinning apparatus.

That is, the present invention is as follows.

1) Polyacetal resin (POM) 50 to 90 wt%, melt flow rate (MFR) 4 to 30 g / 10 minutes polybutyl succinate resin (PBS) or a similar structure resin of PBS or polylactic acid resin 10 to 45 wt% , A single-layer or multi-layer antibacterial fiber having a fiber diameter of 0.5 to 20 μm and comprising a resin composition containing 0 to 5 wt% of a carbodiimide compound.

2) Polyacetal resin (POM) 50 to 90 wt%, melt flow rate (MFR) 4 to 30 g / 10 minutes polybutyl succinate resin (PBS) or a similar structure resin of PBS or polylactic acid resin 10 to 45 wt% , The multi-layered antibacterial fiber according to the previous section, wherein the resin composition containing 0 to 5 wt% of the carbodiimide compound forms the outermost layer.

3) Similar structural resins of polybutyl succinate resin (PBS) are polybutyl succinate adipate (PBSA), polyhydroxybutyrate (PHB), polyhydroxybutyrate-cohydroxyvalerate (PHBV), polybutylene adipate- The antibacterial fiber according to the above 1 and 2 which is one or more resins selected from the group consisting of terephthalate (PBAT) and polyhydroxybutyrate-hydroxyhexanoic acid (PHBH).

4) The multilayer fiber has a core-sheath structure, the core is any of polyolefin resin, polyester resin, polyamide resin, acrylic resin, polyurethane resin, and polyacetal resin, and the sheath is polyacetal resin (POM) 50 to 90 wt%, MFR. 1 to 5 above 3. Antibacterial fiber according to

（式中、Ｒ０及びＲ０’は、同一又は異なってもよく、水素原子、アルキル基、フェニル基又は１以上のエーテル結合で中断されているアルキル基であり、ｍは２〜６の整数である） As the polyoxymethylene resin in the present invention, homopolymers or copolymers of the polyoxymethylene resin can be used. The polyoxymethylene copolymer can be used alone or in combination with polyoxymethylene copolymers having different types and contents of comonomer. The polyoxymethylene copolymer has an oxyalkylene unit represented by the following formula (1) in the molecule in addition to the oxymethylene unit.

(In the formula, R0 and R0'may be the same or different, and are hydrogen atoms, alkyl groups, phenyl groups or alkyl groups interrupted by one or more ether bonds, where m is an integer of 2-6. )

The alkyl group is an unsubstituted or substituted linear or branched alkyl group having 1 to 20 carbon atoms, and a linear or branched alkyl group having 1 to 4 carbon atoms is preferable. Examples of the alkyl group include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, pentyl, hexyl, decyl, dodecyl and octadecyl. Examples of the substituent include a hydroxy group, an amino group, an alkoxy group, an alkenyloxymethyl group and a halogen. Here, examples of the alkoxy group include methoxy, ethoxy, propoxy and the like. Moreover, as an alkenyloxymethyl group, allyloxymethyl and the like can be mentioned.

A phenyl group is an unsubstituted, unsubstituted or substituted alkyl group, an unsubstituted or substituted aryl group, or a halogen-substituted phenyl group. Here, examples of the aryl group include phenyl, naphthyl, anthracyl and the like.

Examples of the alkyl group interrupted by one or more ether bonds include a group represented by the following formula (2).
-CH2-O- (R3-O) P-R4 (2)
(In the formula, R3 is an alkylene group, P represents an integer of 0 to 20, R4 is a hydrogen atom, an alkyl group, a phenyl group or a glycidyl group, and each (R3-O) unit is the same. May be different)

The alkylene group is a linear or branched alkylene group having 2 to 20 carbon atoms which is unsubstituted or substituted, and examples thereof include ethylene, propylene, butylene and 2-ethylhexylene. Ethylene and propylene are preferable as the alkylene as R1.

It is preferable that R0 and R0'are the same and are hydrogen atoms. Examples of the oxyalkylene unit represented by the formula (1) include an oxyethylene unit, an oxypropylene unit, an oxybutylene unit, an oxypentylene unit, and an oxyhexylene unit, preferably an oxyethylene unit, an oxypropylene unit, and an oxypropylene unit. It is an oxybutylene unit, more preferably an oxydimethylene unit, an oxytrimethylene unit, and an oxytetramethylene unit.

The polyoxymethylene copolymer can further have a unit represented by the following formula (3).
-CH (CH3) -CHR5- (3)
(In the formula, R5 is a group represented by the following formula (4))
-O- (R3-O) P-R6 (4)
(In the formula, R6 is a hydrogen atom, an alkyl group, an alkenyl group, a phenyl group or a phenylalkyl group, and R3 and P are as defined in the formula (2)).

The alkenyl group is a linear or branched, unsubstituted or substituted alkenyl group having 2 to 20 carbon atoms, and examples thereof include vinyl, allyl and 3-butenyl. Examples of the alkyl moiety and the phenyl moiety in the phenylalkyl group include the above-mentioned examples of the alkyl group and the phenyl group. Examples of the phenylalkyl group include benzyl, phenylethyl, phenylbutyl, 2-methoxybenzyl, 4-methoxybenzyl, 4- (allyloxymethyl) benzyl and the like. In the present invention, when present, the alkenyl group and glycidyl group in the group represented by the formula (2) or the alkenyl group in the group represented by the formula (4) may serve as a cross-linking point in a further polymerization reaction. It can form a crosslinked structure.

The method for producing the polyoxymethylene copolymer is not particularly limited, but for example, trioxane, which is a trimer of formaldehyde, and a comonomer are bulked using a cationic polymerization catalyst such as boron trifluoride, if necessary. A method of polymerization can be mentioned. Examples of the comonomer include cyclic ethers having 2 to 8 carbon atoms such as ethylene oxide, 1,3-dioxolane, 1,3,5-trioxepane and 1,3,6-trixocan; and cyclic formal and diglycol of glycols. Examples thereof include cyclic formal having 2 to 8 carbon atoms such as cyclic formal. These comonomer forms an oxyalkylene unit represented by the formula (1) in which R0 and R0'are the same and are hydrogen atoms.

In the present invention, the polypolyoxymethylene copolymer also includes a binary copolymer and a multiple copolymer. Therefore, as the polyacetal copolymer of the present invention, a polypolyoxymethylene copolymer having an oxymethylene unit and an oxyalkylene unit represented by the above formula (1), an oxymethylene unit, an oxyalkylene unit represented by the above formula (1) and a formula. A polyacetal copolymer containing the unit represented by (3), the copolymer having a crosslinked structure, and the like can be widely used. In the present invention, the unit represented by the formula (1) in which R0 and R0'are not hydrogen atoms at the same time can be formed by, for example, copolymerizing a glycidyl ether compound or an epoxy compound, and is represented by the formula (3). The represented unit can be formed, for example, by copolymerizing an allyl ether compound.

The glycidyl ether and the epoxy compound are not particularly limited; epichlorohydrin; alkyl glycidyl formal such as methyl glycidyl formal, ethyl glycidyl formal, propyl glycidyl formal and butyl glycidyl formal; ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4 -Butandiol diglycidyl ether, hexamethylene glycol diglycidyl ether, raisonsinol diglycidyl ether, bisphenol A diglycidyl ether, hydroquinone diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether and polybutylene glycol diglycidyl ether Diglycidyl ethers such as glycidyl ethers; triglycidyl ethers such as glycerin triglycidyl ethers and trimethylolpropan triglycidyl ethers; tetraglycidyl ethers such as pentaerythritol tetraglycidyl ethers;

As allyl ether compounds, polyethylene glycol allyl ether, methoxypolyethylene glycol allyl ether, polyethylene glycol-polypropylene glycol allyl ether, polypropylene glycol allyl ether, butoxypolyethylene glycol-polypropylene glycol allyl ether, polypropylene glycol diallyl ether, phenylethyl allyl ether, phenylbutyl Examples thereof include allyl ether, 4-methoxybenzylallyl ether, 2-methoxybenzylallyl ether and 1,4-diallyloxymethylbenzene.

Above all, from the viewpoint of mass productivity and thermal stability, 0.5 to 30 parts by weight, preferably 0.5 to 30 parts by weight, a copolymer composed of one or more cyclic ethers and / or cyclic formal other than trioxane with respect to 100 parts by weight of trioxane. A polypolyoxymethylene copolymer obtained by adding 1 to 15 parts by weight is preferable. If the amount of comonomer is 0.5 parts by weight or more, the heat resistance required for melt spinning is sufficient, and decomposition and foaming of the polypolyoxymethylene copolymer are unlikely to occur inside the extruder or inside the spinning nozzle, resulting in processability. Excellent. When it is 30 parts by weight or less, the yield in producing the polypolyoxymethylene copolymer is improved. The amount of the glycidyl ether compound, the epoxy compound and the allyl ether compound is not particularly limited, but preferably 0.05 to 20 parts by weight of the glycidyl ether compound, the epoxy compound and the allyl ether compound are added to 100 parts by weight of the trioxane. be able to.

The polypolyoxymethylene resin used in the present invention preferably has an MFR of 50 g / 10 minutes or less according to ISO1133. The larger the MFR, the more suitable it is to obtain a finer yarn by melt spinning, but if it is 50 g / 10 minutes or less, there is an advantage that the mechanical properties (particularly toughness) are excellent. The MFR can be adjusted by appropriately adjusting the amount of the chain transfer agent in the polymerization reaction.

The polybutyl succinate resin can be produced by a known method using succinic acid and butanediol as raw materials. For example, a general method of melt polymerization such as esterification reaction and / or transesterification reaction of succinic acid and butanediol and then polycondensation reaction under reduced pressure, or a known solution using an organic solvent. It can also be produced by a heat dehydration condensation method. From the viewpoint of economy and simplification of the manufacturing process, a method of producing by melt polymerization performed without a solvent is preferable.

As products (commercially available products) that can be used as polybutylene succinate resin (synonymous with polybutylene succinate resin), Mitsubishi Chemical's polybutylene succinate resin "BioPBS" (registered trademark), Showa Denko Co., Ltd. Examples thereof include polybutylene succinate resin "Bionore" (registered trademark) manufactured by Shandong Fuwin New Material, polybutylene succinate resin manufactured by BASF, and polybutylene adipate terephthalate resin "Ecoflex" (registered trademark) manufactured by BASF.

Polybutylsuccinate resins include resins with similar structures (similar structural resins), and similar structural resins include polybutylsuccinate adipate (PBSA), polyhydroxybutyrate (PHB), and polyhydroxybutyrate-cohydroxy. Examples thereof include valerate (PHBV), polybutylene adipate-terephthalate (PBAT), and polyhydroxybutyrate-hydroxyhexanoic acid (PHBH), which can be treated equivalently to the polybutylsuccinate resin in the resin composition of the present invention. ..

The optimum MFR for polybutyl succinate resin or similar structures is 4-30 g / 10 min. When the MFR has a high molecular weight of 4 g / 10 minutes or less, or when the MFR has a low molecular weight of 30 g / 10 minutes or more, the compatibility between the resin and the polyacetal resin is poor, and the fiber is given a high degree of stretchability. I can't.

The polylactic acid resin is poly-L-lactic acid obtained by polymerizing only the L-form of lactic acid or poly-D-lactic acid obtained by polymerizing only the D-form, and the D-form and L-form are randomly polymerized or blocked. Polymerized poly-DL-lactic acid can be used. The polylactic acid resin can be produced by a known method. For example, in the lactide method generally adopted in an industrial process, an oligomer obtained by heat dehydration polymerization of lactic acid is further heated and decomposed under reduced pressure to form a dimer of lactic acid. A quantide, lactide, is obtained and polymerized in the presence of a metal salt catalyst to give polylactic acid. Alternatively, in the direct polymerization method, polylactic acid can be produced by heating lactic acid under reduced pressure in a solvent such as diphenyl ether and polymerizing while removing water.

The polylactic acid resin is manufactured by Cargill Dow Inc. of the United States and supplied under the trade name of Nature Works. This is imported and processed by Kanebo Synthetic Fiber Co., Ltd., Kuraray Co., Ltd., Unitika Ltd., and Mitsui Chemicals Co., Ltd. in Japan for a wide range of products such as packaging containers, agricultural civil engineering, compost-related products, sportswear, and bedding products. It is on sale. Polylactic acid resin is commercially available from Unitika Ltd. as "Teramac" (registered trademark).

The carbodiimide compound used in the present invention may be any compound having one or more carbodiimide groups in the molecule. For example, dicyclohexylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, dit-butylcarbodiimide and the like can be mentioned.

In addition, additives generally added to polyoxymethylene resins, polybutyl succinate resins, and polylactic acid resins, for example, oxidation stabilizers, internal lubricants, nucleating agents, and ultraviolet rays, as long as the performance of the fibers is not impaired. Absorbents, colorants, etc. can be used.

A resin composition containing a polyacetal resin as a main component and a polybutylsuccinate resin having an MFR of 4 to 30 g / 10 minutes or a similar structural resin thereof and a carbodiimide compound as a sub-component, or a polyacetal resin as a main component, and a polylactic acid resin and carbodiimi. The resin composition containing the compound as a sub-component can be obtained by kneading with a single-screw or twin-screw extruder according to a known method.

The ratio of the polybutyl succinate resin or a similar structural resin thereof, or the ratio of the polylactic acid resin is preferably 10 to 45 wt%. If it is 10 wt% or less, the stretchability of the fiber is inferior, and it is difficult to make the fiber diameter 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less. On the other hand, if it is 45 wt% or more, the antibacterial property of the fiber is lowered.

The ratio of the carbodiimide compound is preferably 0 to 5 wt%. By adding the carbodiimide compound, the thermal stability of the polyacetal resin composition is improved, and stable fiber thinning (drawing) becomes possible in the spinning process. This is especially effective when the spinning temperature becomes high. If it is 5 wt% or more, no further effect can be expected and it becomes uneconomical.

In the multilayer fiber of the present invention, the resin used for the inner layer excluding the outermost layer, for example, the core layer of the fiber having a core-sheath structure, is any of a polyolefin resin, a polyester resin, a polyamide resin, an acrylic resin, a polyurethane resin, and a polyacetal resin. Is it? As the polyolefin resin, polypropylene resin and polyethylene resin are suitable. The polyeztel resin and the polyamide resin are preferably copolymers having a melting point of 240 ° C. or lower.

<Fiber manufacturing method>
The method for producing the antibacterial resin fiber of the present invention can be produced by a known melt spinning method. That is, a polyacetal resin and a polybutyl succinate resin or a similar structural resin and a carbodiimide compound are melt-kneaded in advance at a predetermined ratio, or a polyacetal resin and a polylactic acid resin and a carbodiimide compound are melt-kneaded by a single-screw or twin-screw extruder and pelletized. To manufacture. The obtained polyacetal resin composition is melted by a spinning machine and extruded from a fiber die, and a take-up spinning fiber is produced by a winding machine.

Further, a drawing treatment is performed to adjust the spun fiber to a desired fineness. The stretching treatment can be performed by a known stretching method. Examples include wet stretching performed in a warm water bath, dry stretching performed in dry air or using a heated metal roll, and steam stretching performed in a superheated steam atmosphere heated to a temperature of 100 ° C. or higher. Among these, in the production of the core-shell type composite fiber of the present invention, it is preferable to wet-stretch in a warm water bath at 40 to 100 ° C., preferably in a warm water bath at 50 to 90 ° C. Alternatively, the extruded fibers can be brought into contact with a hot plate at 80 to 120 ° C. and stretched in a dry manner.

The fibers are produced as monofilaments or multifilament fibers, and a method for producing multifilaments is preferable as a method for producing ultrafine fibers. In the production of the multifilament, the molten resin is cooled from a plurality of die holes, the obtained fibers are taken up by a take-up roll, and then the fibers are drawn by a drawing roll. Alternatively, the melt-spun fiber having a fiber diameter of 20 to 100 μm can be once wound up to have a fiber diameter of 0.5 to 10 μm by another drawing machine.

As a method of using a woven fabric produced from stretched fibers, underwear, sheets, pillowcases, socks, medical uniforms, etc. that make use of its antibacterial properties are useful. Further, the fibers thinned to 0.5 to 10 μm are crimped, the orientation directions of the fibers are aligned by a carding device, and then the fibers are entangled with each other by a needle punching device to produce a non-woven fabric. Can be done.

Since the polyacetal alloy resin fiber containing the polyacetal resin of the present invention as a main component can be easily stretched to a high degree and can produce ultrafine fibers, bacteria, fine dust, and suspended matter in the air such as PM2.5. , It is possible to make a filter that is extremely effective in collecting pollen and the like.

The best mode for carrying out the invention will be described below.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the Examples shown below as long as the gist of the present invention is not exceeded.
<Examples and Comparative Examples>

<Raw materials>
-As a polyacetal resin (POM),
POM-1: Jupital F20-02 (manufactured by Mitsubishi Engineering Plastics)
POM-2: Jupital F30-03 (manufactured by Mitsubishi Engineering Plastics) was used.
-As a polybutyl succinate (PBS) resin, PBS-1: Bio-BPS FZ71 (manufactured by Mitsubishi Chemical Corporation) with an MFR of 22.
PBS-2: Bio-BPS FZ91 with MFR of 5 (manufactured by Mitsubishi Chemical Corporation)
PBS-3: Bionore # 1001 with MFR of 1.5 (manufactured by Showa Denko)
PBS-4: Bio-BPS FZ71 was added with 3% by weight of calcium stearate and melt-extruded at a resin temperature of 200 ° C. to adjust the MFR to 35.
・ AONILEX (manufactured by Kaneka) was used as the PHBH resin. ・ Terramax TP-4000 (manufactured by Unitika) was used as the polylactic acid resin.
-Primepolypro F-730NV (made of prime polymer) as polypropylene (PP) resin, MA-1340 (made by Unitica) as polyester (PET) resin, and 6/66 common weight as polyamide (PA) resin. The combined 5034 (manufactured by Ube Kosan) was used.
-As the carbodiimide resin, carbodilite LA-1 (manufactured by Nisshinbo Chemical Co., Ltd.) was used.

<Preparation of composition for evaluation>
The composition of the evaluation sample is shown in Table-1. After weighing each component, dry blending was performed, and the mixture was put into the hopper of a twin-screw kneader and melt-kneaded to produce pellets having a desired composition. The obtained pellets were dried and then used in a spinning experiment.

(Table-1)

<Melting spinning>
For melt spinning, a spinning machine in which two vertical single-screw extruders (A and B) were combined was used. When manufacturing single-layer fibers, the same material is put into each of A and B and extruded, and when making double-structured fibers, different materials are put into the extruders of A and B. Fibers with different properties can be produced in the core shell. The extruders A and B have a screw having a shaft diameter of 25 mm and a heating cylinder around the screw, and the molten resin is guided to the die through a flow path connected to the die. The die holes have 24 holes arranged in a circular shape, and each die hole has a double structure. From the extruder A to the internal die hole, from the extruder B The molten resin is guided to the die hole on the outer circumference, and the core-shell type molten resin is discharged in the form of threads. The outer diameter of the die hole is 300 μm, and the inner diameter of the core portion is 200 μm. The screw and cylinder of the extruder, the inner surface of the flow path through which the molten resin flows, and the inner surface of the die are chrome-plated.

The temperature of the extruder and die can be controlled to 160-250 ° C. depending on the melting temperature of the resin used. The molten resin discharged from the nozzle is picked up by using five rollers, and usually, the rotation speed of each roller can be sequentially increased to stretch the resin. In this case, it is effective to control the surface temperature of the roller to 80 to 120 ° C. In this way, core-shell fibers having a fiber diameter of 20 to 100 μm were produced. In the case of a single-layer fiber, the same material was put into each of the extruders A and B for spinning. In the case of multi-layer fibers, different materials were added to A and B. A multilayer fiber having a fiber diameter of 20 to 100 μm having a core-sheath structure in which the resin charged in A serves as a core and the resin charged in B serves as a sheath was produced.

Further, once the wound fiber was heated again and stretched, a fiber having a fiber diameter of 0.5 to 20 μm was produced. The fibers wound around the bobbin were guided to the drawing device, and the drawing ratio was adjusted by the difference between the speed of the rotating roll in front of the heating device for drawing and the rotation speed and diameter of the winding roll after the heating device. As the heating device, a method of passing through an pneumatic heater at 100 to 140 ° C. was used. In addition, a method of passing through a bathtub or an oil bath is also effective. The heating device may be in one stage, or a plurality of stages may be used to increase the degree of stretching to a desired degree.

<Measurement of MFR>
Compliant with JIS K7210, ISO1133, ASTM D1238. The measurement temperature is 190 ° C., the load is 2.16 kg, and the unit of MFR is g / 10 minutes.

<Evaluation of antibacterial properties of fibers>
The bacterial solution absorption method is specified in JIS L1902. This method is a test assuming the wearing of clothing, and evaluates the antibacterial effect by comparing the growth of bacteria on the standard cloth and the test cloth. As the test bacteria, (1) Staphylococcus aureus NBRC12732 (2) Escherichia coli NBRC3301 was used for Escherichia coli, and the sample before the test was autoclaved. Inoculum concentration (CFU / ml) is 1.5 * 10 ^5. The antibacterial property of the fiber is indicated by the antibacterial activity value "A". This antibacterial activity value is calculated by Eq. (1).
A = (LogCb-LogCa)-(LogC2-LogC1) (1 set)
Ca: Number of viable bacteria on standard cloth Cb: Number of viable bacteria after 24-hour culture on standard cloth C1: Number of viable bacteria on evaluation sample C2: Number of viable bacteria after 24-hour culture on evaluation sample

<Result>
Examples and comparative examples are shown in Table-2. In Examples -1 to 3, POM resin 50 to 90 wt%, melt flow rate (MFR) 4 to 30 g / 10 min PBS resin or PBS similar structure resin or polylactic acid resin 10 to 45 wt%. , Carbodiimide compound A monolayer fiber of a polyacetal composition in the range of 0 to 5 wt%, the fiber diameter of the stretched fiber is 20 μ or less, and the antibacterial activity value “A” is 5 or more, showing high antibacterial properties. There is. According to the JIS standard, "A" is 2 or more, and according to the SEK standard, "A" is 2.2 or more, which is considered as an antibacterial processed product, and shows far superior antibacterial properties. Examples-4 to 8 are multilayer fibers in which the polyacetal resin composition of the present invention is present in the outermost layer, and all show a high antibacterial activity value "A".

Comparative Examples-1 and 2 have compositions in which the melt flow rate (MFR) of PBS is out of the claimed range, and when the fibers are tried to be stretched to 20 μm or less, the fibers are broken and thinned. It shows that it is difficult. Comparative Example-3 shows that the antibacterial effect is significantly reduced when the proportion of PBS in the polyacetal resin composition is 70 wt%, which is out of the claimed range. In Comparative Example-4, when the polyacetal resin is not present in the outermost layer of the multilayer fiber, in Comparative Example-5 and Comparative Example 7, the ratio of PBS or PLA in the polyacetal resin composition formed in the outermost layer of the multilayer fiber is When it is out of the claimed range, it shows that the antibacterial property is significantly low. Comparative Example-6 is a case where the melt flow rate (MFR) of PBS in the polyacetal resin composition forming the outermost layer of the multilayer fiber is out of the claimed range, and Comparative Example-8 is a case where the multilayer fiber is formed. It is shown that when the resin forming the outermost layer is not a polyacetal resin composition but a polyacetal resin alone, fiber breakage occurs when the resin is stretched so that the fiber diameter is 20 μm or less.

(Table-2)

Claims (4)

Polyacetal resin (POM) 50-90 wt%, melt flow rate (MFR) 4-30 g / 10 min Polybutyl succinate resin (PBS) or similar structural resin of PBS or polylactic acid resin 10-45 wt%, carbodiimide A single-layer or multi-layer antibacterial fiber having a fiber diameter of 0.5 to 20 μm and comprising a resin composition containing 0 to 5 wt% of the compound. Polyacetal resin (POM) 50-90 wt%, melt flow rate (MFR) 4-30 g / 10 min Polybutyl succinate resin (PBS) or similar structural resin of PBS or polylactic acid resin 10-45 wt%, carbodiimide The multilayer antibacterial fiber according to claim 1, wherein the resin composition containing 0 to 5 wt% of the compound forms the outermost layer. Similar structural resins of polybutyl succinate resin (PBS) are polybutyl succinate adipate (PBSA), polyhydroxybutyrate (PHB), polyhydroxybutyrate-cohydroxyvalerate (PHBV), polybutylene adipate-terephthalate (PHBV). The antibacterial fiber according to claim 1 and 2, which is one or more resins selected from the group consisting of PBAT) and polyhydroxybutyrate-hydroxyhexanoic acid (PHBH). The multilayer fiber has a core-sheath structure, the core is any of polyolefin resin, polyester resin, polyamide resin, acrylic resin, polyurethane resin, and polyacetal resin, the sheath is polyacetal resin (POM) 50 to 90 wt%, and MFR is 4. Claims 1 to 3 comprising a resin composition containing 10 to 45 wt% of a polybutyl succinate resin (PBS) or a similar structure resin of PBS or a polylactic acid resin and 0 to 5 wt% of a carbodiimide compound at ~ 30 g / 10 min. 3. Antibacterial fiber according to