JP7595935B2 - Antibacterial Fabric - Google Patents

Description

The present invention relates to an antibacterial fabric in which single-layer or multi-layer synthetic fibers, consisting of 50-100 wt% POM and 0-50 wt% biodegradable polyester resin, account for 30-70 wt% of the entire fabric, and natural fibers such as silk, cotton, wool, and hemp account for 30 to 70 wt%.

Natural fibers or synthetic resin fibers are used as important products in various fields, not just clothing, and are indispensable in our lives. Many of these products require antibacterial properties. However, natural fibers such as silk, wool, hemp, and cotton, which have been widely used as conventional fibers, and synthetic fibers such as polyester fibers, polyamide fibers, polyolefin fibers, acrylic fibers, and polyurethane fibers, do not have antibacterial properties, and therefore various techniques for imparting antibacterial properties have been proposed. Patent Documents 1 and 2 disclose a technique for attaching an antibacterial agent to a fiber via a binder resin. Another method, such as a method of kneading an antibacterial agent into a resin, is disclosed in Patent Documents 3 and 4. Many antibacterial agents use silver ions, and those supported by inorganic compounds such as apatite, glass, zeolite, and clay compounds have been proposed. Although these methods are effective at first, the inorganic compounds supporting the antibacterial agent fall off due to wear and washing, and the effect of the antibacterial agent is lost early. In addition, they also have the disadvantage of discoloration due to processing steps after spinning and changes over time.

Many fibers themselves do not have antibacterial properties, and in order to make them antibacterial, the above-mentioned methods must be used. However, POM is the only fiber whose resin itself has antibacterial properties, and it is useful for use in applications around water as injection molded or extrusion molded products. However, POM has excellent crystallinity, a fast crystallization rate, and a high degree of crystallization, so it has been considered difficult to use as a fiber. In recent years, there has been active research into using POM as a fiber. POM fiberization technology is disclosed in Patent Document 5, Patent Document 6, Patent Document 7, etc.

Patent Document 8 also discloses that POM can be made into fibers to take advantage of its germ-repellent and antibacterial properties. However, as mentioned above, POM has a drawback in that it is difficult to stretch due to its fast crystallization rate and high degree of crystallization, making it difficult to make thin fibers. Another characteristic of POM is that it is difficult to dye. To use POM fibers for clothing applications, it is preferable that they can be easily dyed using conventional methods. Natural fibers such as silk, cotton, wool, and hemp have unique textures, feel, luster, and moisture retention, and are reliable because they have been used by humans for a long time. However, natural fibers have problems such as poor antibacterial, antifungal, and insect-repellent properties, and are sometimes very expensive.

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

The purpose of this invention is to create a never-before-seen textile by utilizing the antibacterial properties of POM fibers while taking advantage of the luxury, dyeability, moisture retention, and reliability of natural fibers. Fibers that use antibacterial agents have problems with long-term antibacterial durability and discoloration. On the other hand, synthetic fibers made of POM or alloys of POM and specific biodegradable polyester resins have excellent antibacterial properties without the use of antibacterial agents. In particular, alloys of POM and PBS or PLA are easy to draw during spinning, making it easy to produce fine fibers (fiber diameter 20 μm or less). Since fine fiberization is advantageous for exerting antibacterial properties, the above-mentioned fine fiberization characteristics of the alloy are desirable.

The inventors have found that a hybrid fabric made of a single-layer or multi-layer fiber consisting of an alloy (including POM alone) of 50-100 wt% POM and 0-50 wt% of a specific biodegradable polyester resin, which combines a synthetic fiber with a fiber diameter of 0.5-100 μm with a natural fiber such as silk, cotton, wool, hemp, or kenaf, has extremely excellent antibacterial properties and provides a new fabric that has the texture, feel, luster, and moisture retention properties of natural fibers. As the biodegradable polyester resin to be used in combination with POM, PBS or a resin with a similar structure to PBS or PLA with a melt flow rate (MFR) of 4-30 g/10 min is preferable. As for the form of the fabric, it can be used in the form of knitted fabric, woven fabric, nonwoven fabric, web, etc., and can be easily used for clothing, bedding, interior decoration, etc.

The synthetic fibers made of POM or POM and a specific biodegradable polyester resin used by the present inventors can be produced by a normal melt spinning method. Single-layer or multi-layer synthetic fibers with a fiber diameter of 0.5 to 100 μm can be produced by first melt-spinning fibers with a fiber diameter of 20 to 500 μm and then stretching the fibers in one or multiple stages to a fiber diameter of 0.5 to 100 μm. Polyacetal alloy resin fibers have high stretchability, and can be produced into ultrafine fibers with extremely high production efficiency using normal melt spinning equipment.

That is, the present invention is as follows.
1) An antibacterial hybrid fabric in which single-layer or multi-layer synthetic fibers with a fiber diameter of 0.5 to 100 μm obtained from an alloy of 50 to 100 wt % POM and 0 to 50 wt % biodegradable polyester resin (including POM alone) account for 30 wt % to 70 wt % of the entire fabric, and natural fibers account for 30 wt % to 70 wt % of the entire fabric.

2) The antibacterial hybrid fabric according to claim 1, in which the synthetic fibers account for 50-70% of the entire fabric, and the natural fibers account for 30-50% of the entire fabric.

3) The hybrid fabric according to any one of claims 1 to 3, wherein the biodegradable polyester resin is one or more resins selected from the group consisting of PLA, PBS, polybutylene succinate adipate (PBSA), polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), polybutylene adipate-terephthalate (PBAT), and polyhydroxybutyrate-hydroxyhexanoate (PHBH).

4) A hybrid fabric in which the synthetic fiber has a core-sheath structure, the core is either polyolefin resin, polyester resin, polyamide resin, acrylic resin, polyurethane resin, or POM, and the sheath is 50-100 wt% POM and 0-50 wt% PBS or a resin with a similar structure to PBS or PLA with an MFR of 4-30 g/10 min.

5) An antibacterial hybrid woven or nonwoven fabric according to claim 1, which is composed of 50-90 wt% POM and 10-45 wt% PBS or a resin with a similar structure to PBS, or PLA, with a melt flow rate (MFR) of 4-30 g/10 min.

The fiber of the present invention, which is mainly composed of polyacetal (POM) resin, has excellent antibacterial properties by itself. A hybrid woven fabric or nonwoven fabric that combines this with natural fibers, such as silk, cotton, wool, and hemp, and uses 30 wt % to 70 wt % of the entire fabric, and POM fibers and natural fibers, can provide an excellent woven fabric or nonwoven fabric that has the texture, feel, luster, and moisture retention of natural fibers, and has the reliability that mankind has used for a long time and the antibacterial properties that are characteristic of POM fibers.

<Method of manufacturing synthetic fibers>
The method for producing the fibers made of POM or POM and a biodegradable polyester resin, for example, PBS or a resin with a similar structure to PBS, or an alloy of PLA, used in the antibacterial woven or nonwoven fabric of the present invention, can be produced by a known melt spinning method. That is, POM or POM and PBS or a resin with a similar structure, or POM and PLA, are melt-kneaded in advance in a predetermined ratio using a single-screw or twin-screw extruder to produce pellets. At this time, it is preferable to add 0.1 to 5 wt% of a carbodiimide compound to 100 wt% of PBS or a resin with a similar structure to PBS or an alloy of PLA. The synthetic fibers can have a single layer or a multilayer structure. When a multilayer structure is used, the outermost layer can be made of POM or a resin made of POM and a biodegradable polyester resin, for example, PBS or a resin with a similar structure to PBS, or an alloy of PLA, and the inner layer can be made of a polyolefin resin, a polyester resin, a polyamide resin, an acrylic resin, a polyurethane resin, or POM.
Next, the resulting POM composition is melted in a spinning machine, extruded through a fiber die, and taken up by a winder to produce spun fibers.

Furthermore, the spun fibers are stretched to adjust them to the desired fineness. The stretching can be performed by a known stretching method. Examples include wet stretching in a warm water bath, dry stretching in dry air or using a heated metal roll, and steam stretching in a superheated steam atmosphere heated to a temperature of 100°C or higher. Among these, when producing the polyacetal resin (POM) composition fiber of the present invention, it is preferable to perform wet stretching in a warm water bath at 40 to 100°C, preferably a warm water bath at 50 to 90°C. Alternatively, the extruded fiber can be brought into contact with a hot plate at 80 to 120°C for dry stretching.

Synthetic fibers obtained from POM fibers or alloys of POM and biodegradable polyester resin are produced as monofilament or multifilament fibers, but the preferred method for producing ultrafine fibers is to produce multifilament fibers. To produce multifilament fibers, molten resin is extruded from multiple die holes and cooled, the resulting fibers are taken up by a take-up roll, and then the fibers are stretched by a stretching roll. Alternatively, melt-spun fibers with a fiber diameter of 20 to 100 μm can be wound up once and then stretched to a fiber diameter of 0.5 to 20 μm by a separate stretching machine.

<Manufacturing method of hybrid fabrics made from synthetic and natural fibers>
The POM fiber thus produced or the synthetic fiber obtained from an alloy of POM and biodegradable polyester resin is wound on a bobbin, and a natural fiber is used for the warp of the loom and a POM fiber for the weft, or vice versa, to produce a hybrid fabric in which POM fiber and natural fiber are woven vertically and horizontally. The finished woven fabric will be more beautiful if the thickness (decitex) of the fibers used vertically and horizontally is roughly the same. The ratio of POM fiber to natural fiber can be adjusted by the number of bobbins used vertically and horizontally.

It is also possible to produce a single fiber by twisting together the desired number of synthetic fibers, obtained from POM fibers or an alloy of POM resin and biodegradable polyester resin, and natural fibers. By adjusting the number of POM fibers and natural fibers when threading the fibers from each bobbin into a twisting machine, a yarn with the desired POM fiber ratio can be easily obtained. By weaving this yarn into cloth on a knitting machine, a fabric made from a blend of POM fibers and natural fibers can be produced.

<Method for producing a hybrid nonwoven fabric of synthetic and natural fibers (1)>
A hybrid nonwoven fabric of synthetic and natural fibers obtained from POM fiber or an alloy of POM resin and biodegradable polyester resin is first produced by melt spinning a resin composition containing 50-100 wt% POM resin and 0-50 wt% PBS or a resin similar in structure to PBS with a melt flow rate (MFR) of 4-30 g/10 min, or PLA, and then stretching the 20-100 μm fiber to a 0.5-20 μm fiber, which is then wound on a bobbin. A bobbin wound with natural fiber of a desired fineness is separately prepared, and the bobbin is introduced into a crimping machine in a desired ratio with POM fiber or POM alloy fiber to produce raw cotton. Next, the raw cotton is oriented in the same direction using a carding device, and then the fibers are entangled with each other using a needle punch device, thereby producing a nonwoven fabric containing a mixture of synthetic and natural fibers.

<Method of manufacturing melt-blown nonwoven fabrics made from synthetic and natural fibers (2)>
Alternatively, a resin composition containing 50 to 100 wt % POM and 0 to 50 wt % PBS or a resin with a similar structure to PBS or PLA resin with a melt flow rate (MFR) of 4 to 30 g/10 min is heated and melted in an extruder, and as it is extruded from a nozzle, it is blown away forcefully with compressed air and collected in a collector made of wire mesh, and the POM or POM alloy fiber cotton thus obtained and separately prepared natural fiber cotton are introduced into a carding device in a desired ratio, the fibers are entangled with each other to align the fiber orientation direction, and then the fibers are entangled with each other in a needle punch device, thereby producing a nonwoven fabric.

When manufacturing nonwoven fabric, after needle punching, the entire fabric is heated and compressed with a hot plate press to heat fuse the synthetic fibers together, thereby increasing the tensile strength of the nonwoven fabric. In this case, the synthetic fibers are made into a core-shell type double-structure fiber, and by using an alloy resin of POM resin and PBS resin or a resin with a similar structure to PBS or 0-50 wt% PLA resin for the shell, the shells, which have a melting point 10 to 50°C lower than that of the POM resin, are heat-fused together, and a strong nonwoven fabric can be manufactured without melting the POM resin in the core. In particular, when an alloy of PBS or a resin with a similar structure to PBS and POM is used for the shell, the melting point difference with the POM core is 10°C to 50°C, so the tensile strength of the nonwoven fabric after heat fusion is high, making it possible to produce a strong nonwoven fabric.

<Production method of polyacetal resin>
As the POM in the present invention, a POM homopolymer or copolymer can be used. The POM copolymer can be used alone or in the form of a mixture of POM copolymers having different types and amounts of comonomers. The POM copolymer has an oxyalkylene unit represented by the following formula (1) in addition to the oxymethylene unit in the molecule. Note that polyacetal resin and polyoxymethylene resin are synonymous.

（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）

(In the formula, R0 and R0' may be the same or different and each represents a hydrogen atom, an alkyl group, a phenyl group, or an alkyl group interrupted by one or more ether bonds, and m is an integer of 2 to 6.)

The alkyl group is an unsubstituted or substituted linear or branched alkyl group having 1 to 20 carbon atoms, and preferably a linear or branched alkyl group having 1 to 4 carbon atoms. 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, and propoxy. Examples of the alkenyloxymethyl group include allyloxymethyl.

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

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

The alkylene group is a linear or branched, unsubstituted or substituted alkylene group having 2 to 20 carbon atoms, such as ethylene, propylene, butylene, and 2-ethylhexylene. The alkylene represented by R1 is preferably ethylene or propylene.

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

The polyoxymethylene (POM) copolymer may further include 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 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. The alkyl and phenyl portions of the phenylalkyl group are exemplified by the alkyl and phenyl groups described above. Examples of the phenylalkyl group include benzyl, phenylethyl, phenylbutyl, 2-methoxybenzyl, 4-methoxybenzyl, and 4-(allyloxymethyl)benzyl. In the present invention, when present, the alkenyl and glycidyl groups in the group represented by formula (2) or the alkenyl group in the group represented by formula (4) can serve as crosslinking points in a further polymerization reaction, thereby forming a crosslinked structure.

The method for producing polyoxymethylene (POM) copolymer is not particularly limited, but examples include a method of bulk polymerizing trioxane, which is a trimer of formaldehyde, and a comonomer, using a cationic polymerization catalyst such as boron trifluoride as necessary. 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-trixocane; and cyclic formals having 2 to 8 carbon atoms, such as cyclic formals of glycol and cyclic formals of diglycol. These comonomers form an oxyalkylene unit represented by formula (1), in which R0 and R0' are the same and are hydrogen atoms.

In the present invention, the polyoxymethylene (POM) copolymer includes a binary copolymer and a multi-component copolymer. Therefore, as the POM copolymer of the present invention, a POM copolymer having an oxymethylene unit and an oxyalkylene unit represented by the above formula (1), a POM copolymer containing an oxymethylene unit, an oxyalkylene unit represented by the above formula (1) and a unit represented by the formula (3), and the above copolymer further having a crosslinked structure can be widely used. In the present invention, the unit represented by formula (1) in which R0 and R0' are not simultaneously hydrogen atoms can be formed, for example, by copolymerizing a glycidyl ether compound or an epoxy compound, and the unit represented by formula (3) can be formed, for example, by copolymerizing an allyl ether compound.

The glycidyl ether and epoxy compound are not particularly limited, but include epichlorohydrin; alkyl glycidyl formals such as methyl glycidyl formal, ethyl glycidyl formal, propyl glycidyl formal, and butyl glycidyl formal; diglycidyl ethers such as ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, hexamethylene glycol diglycidyl ether, raisoncinol diglycidyl ether, bisphenol A diglycidyl ether, hydroquinone diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and polybutylene glycol diglycidyl ether; triglycidyl ethers such as glycerin triglycidyl ether and trimethylolpropane triglycidyl ether; and tetraglycidyl ethers such as pentaerythritol tetraglycidyl ether.

Allyl ether compounds include 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 allyl ether, 4-methoxybenzyl allyl ether, 2-methoxybenzyl allyl ether, and 1,4-diallyloxymethylbenzene.

Among them, from the viewpoint of mass productivity and thermal stability, a polyoxymethylene (POM) copolymer obtained by adding 0.5 to 30 parts by weight, preferably 1 to 15 parts by weight, of a comonomer consisting of one or more cyclic ethers and/or cyclic formals other than trioxane to 100 parts by weight of trioxane is preferred. If the comonomer is 0.5 parts by weight or more, the heat resistance required for melt spinning is sufficient, and the POM copolymer is less likely to decompose or foam in the stagnant parts inside the extruder or the spinning nozzle, resulting in excellent processability. If the amount is 30 parts by weight or less, the yield when producing the POM copolymer is improved. In addition, the amounts of the glycidyl ether compound, epoxy compound, and allyl ether compound are not particularly limited, but preferably 0.05 to 20 parts by weight of the glycidyl ether compound, epoxy compound, and allyl ether compound can be added to 100 parts by weight of trioxane.

The polyacetal resin (POM) used in the present invention preferably has an MFR of 50 g/10 min or less according to ISO 1133. The higher the MFR, the more suitable it is for obtaining fine threads by melt spinning, but if the MFR is 50 g/10 min or less, there is an advantage in that the mechanical properties (especially toughness) are excellent. The MFR can be adjusted by appropriately adjusting the amount of chain transfer agent in the polymerization reaction of the POM.

<Production method of polybutylene succinate resin (PBS)>
PBS can be produced by a known method using succinic acid and butanediol as raw materials. For example, it can be produced by a general melt polymerization method such as carrying out an esterification reaction and/or an ester exchange reaction between succinic acid and butanediol, followed by a polycondensation reaction under reduced pressure, or by a known solution heating dehydration condensation method using an organic solvent. From the viewpoint of economy and simplicity of the production process, a method of producing by melt polymerization carried out without a solvent is preferred.

Examples of products (commercially available products) that can be used as PBS-based resins include Mitsubishi Chemical's BioPBS (registered trademark), Showa Denko's Bionolle (registered trademark), PBS resins manufactured by Shandong Fuwin New Material Co., Ltd., and BASF's polybutylene adipate terephthalate-based resin Ecoflex (registered trademark).

There are resins with similar structures to PBS-based resins (resins with similar structures), including polybutylene succinate adipate (PBSA), polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), polybutylene adipate-terephthalate (PBAT), and polyhydroxybutyrate-hydroxyhexanoate (PHBH), which can be treated as equivalent to polybutylene succinate resin (PBS) in the resin composition of the present invention.

The optimal MFR for PBS or similar structures is 4 to 30 g/10 min. If the MFR is a high molecular weight of 4 g/10 min or less, or if the MFR is a low molecular weight of 30 g/10 min or more, the compatibility of the resin with POM is poor, and the fibers cannot be stretched to a high degree.

<Production method of polylactic acid resin (PLA)>
PLA can be poly-L-lactic acid obtained by polymerizing only the L-form of lactic acid, poly-D-lactic acid obtained by polymerizing only the D-form, or poly-DL-lactic acid obtained by randomly polymerizing or block polymerizing the D- and L-forms. PLA can be produced by known methods. For example, in the lactide method generally used in industrial processes, lactic acid is heated and polymerized by dehydration, and the resulting oligomer is further decomposed by heating under reduced pressure to obtain lactide, which is a dimer of lactic acid, and this is polymerized in the presence of a metal salt catalyst to obtain PLA. Alternatively, in the direct polymerization method, PLA can be produced by heating lactic acid in a solvent such as diphenyl ether under reduced pressure and polymerizing while removing water.

PLA is manufactured as a polymer by the American company Cargill Dow and supplied under the product name Nature Works. It is imported into Japan and processed by Kanebo Gohsen Co., Ltd., Kuraray Co., Ltd., Unitika Co., Ltd., and Mitsui Chemicals Co., Ltd. for sale in a wide range of applications including packaging containers, agricultural and civil engineering products, compost-related products, sportswear, and bedding products. Unitika Co., Ltd. sells PLA under the registered trademark "Terramac."

In the present invention, 0.1 to 5 wt % of a carbodiimide compound can be added to 100 wt % of PBS or a resin with a similar structure to PBS or polylactic acid resin. The carbodiimide compound may be any compound having one or more carbodiimide groups in the molecule. For example, dicyclohexylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, t-butylisopropylcarbodiimide, diphenylcarbodiimide, di-t
-butylcarbodiimide and the like.

Additives that are commonly added to POM, PBS, or PLA, such as oxidation stabilizers, internal lubricants, nucleating agents, UV absorbers, colorants, etc., can also be used as long as they do not impair the performance of the fiber.

Alloys of POM with PBS or a resin with a similar structure having an MFR of 4 to 30 g/10 min, or alloys of POM and POLY-PLA, can be obtained by kneading in a single-screw or twin-screw extruder according to known methods.

The ratio of PBS or a resin with a similar structure, or the ratio of PLA, is preferably 0 to 50 wt%. In particular, higher antibacterial properties can be obtained by making the fiber diameter 20 μm or less, preferably 10 μm or less, but to make the fiber diameter thinner, an alloy with PBS or a resin with a similar structure, or an alloy with PLA, at 10 to 40 wt% of the POM can be used to obtain fibers with excellent stretchability.

By adding 0.1 to 5 wt% of a carbodiimide compound to 100 wt% of PBS or a resin with a similar structure to PBS, or PLA, the thermal stability of the polyacetal resin composition is improved, making it possible to stably thin the fibers (draw them) during the spinning process. This is particularly effective when the spinning temperature is high. If the amount is more than 5 wt%, 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 one of polyolefin resin, polyester resin, polyamide resin, acrylic resin, polyurethane resin, and POM. As the polyolefin resin, polypropylene resin and polyethylene resin are preferable. As the polyester resin and polyamide resin, copolymers having a melting point of 240°C or less are preferable.

In the present invention, the natural fibers used together with the single-layer or multi-layer antibacterial fiber with a fiber diameter of 0.5 to 20 μm, which is made of a resin composition containing 50 to 100 wt% POM, PBS or a resin with a similar structure to PBS and a melt flow rate (MFR) of 4 to 30 g/10 min, or 0 to 50 wt% PLA, are plant fibers such as cotton and hemp, but fruit fibers such as coconut, kenaf, rush, and wheat straw can also be used. Cellulosic regenerated fibers or semi-synthetic fibers such as rayon, cupra, polynosic, acetate, triacetate, and promix can also be used. Representative animal fibers include silk and wool, but feather fibers such as down and feathers can also be used.

The antibacterial hybrid fabric of the present invention is less susceptible to insect damage and odor generation during storage. In addition, compared to 100% natural fiber fabrics, it is easier to handle, such as being easier to dry after washing. Generally, silk and wool fabrics are expensive and are often stored for long periods of time, and require careful attention to insect control, but the hybrid fabric of the present invention is easy to maintain. In addition, natural fibers such as cotton and linen are the most comfortable materials to wear in the summer because they absorb sweat easily and have excellent ventilation, but they have the problem of being easily susceptible to the proliferation of Moraxella bacteria, which cause odor. The hybrid fabric of the present invention can prevent the generation of this odor-causing bacteria.

A new effect of the present invention is the change in the texture of the woven fabric. This texture is what is called the touch or feel, and is extremely sensory, so it is difficult to evaluate objectively, but universal values can be obtained by measuring the bending, tensile, shear strength, compressive strength, and surface roughness of the woven fabric. Among them, the measurement method of the drape coefficient is specified in JIS L1096, and the stiffness and softness of the fabric can be expressed by the drape coefficient. For example, the drape coefficient of silk is 0.2 to 0.4, but a woven fabric in which it is blended with about 50% POM fiber has a drape coefficient of 0.7 to 0.9, and the fabric has a slightly crisp feel and is suitable for casual wear. The same tendency occurs when the natural fiber is wool. The drape coefficient of cotton and linen does not change much when blended with POM, but it becomes smooth to the touch. Such a change in feel is considered to be useful for developing uses for fibers that are different from conventional uses.
When combining silk and POM fibers to achieve both antibacterial properties and a casual feel, it is desirable for the synthetic fibers to make up 40-60% of the total fabric, and the natural fibers to make up 40-60% of the total fabric. A similar ratio is also recommended for wool, an animal fiber. This blend ratio gives the fabric an easy-to-handle, casual feel while retaining the luxury feel of natural fibers.
The combination of POM fiber and vegetable fibers such as cotton or hemp does not have a large effect on the drape coefficient, but the difference in texture is apparent when visually inspected or touched. On the other hand, the antibacterial properties drop sharply when the POM fiber content is 30% or less, so the preferred range for antibacterial properties and texture is 50% to 70% POM fiber and 30% to 50% vegetable natural fibers.
The drapeability of nonwoven fabrics is more influenced by the thickness of the fibers, the entanglement of the fibers, or the thermal fusion of the fibers than by the combination of fiber materials, and therefore the drapeability of nonwoven fabrics was not measured in the present invention.

The present invention will be described in more detail below with reference to examples and comparative examples. However, 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>

<Ingredients>
・Polyacetal resin (POM):
POM-1: Iupital F20-02 (manufactured by Mitsubishi Engineering Plastics Corporation)
POM-2: Iupital F30-03 (manufactured by Mitsubishi Engineering Plastics Corporation) was used.
POM-3: Iupital F40-03 (manufactured by Mitsubishi Engineering Plastics Corporation) was used.
・Polybutylene succinate (PBS) resin:
PBS-1: Bio-BPS FZ71 (manufactured by Mitsubishi Chemical) with MFR of 22
PBS-2: Bio-BPS FZ91 with MFR of 5 (manufactured by Mitsubishi Chemical)
PBS-3: Bionolle #1001 (manufactured by Showa Denko) with MFR of 1.5
PBS-4: Bio BPS FZ71 with 3% by weight calcium stearate
The mixture was 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. - Terramac TP-4000 (manufactured by Unitika) was used as the polylactic acid resin (PLA).
・The polypropylene (PP) resin is Prime Polypro F-730NV (manufactured by Prime Polymer), and the polyester (PET) resin is MA-1.
As the polyamide (PA) resin, 5034 (manufactured by Ube Industries, Ltd.), a 6/66 copolymer, was used.
The carbodiimide compound used was Carbodilite LA-1 (manufactured by Nisshinbo Chemicals).

<Preparation of resin composition for evaluation>
The synthetic resin for the evaluation sample was a commercially available POM that had been dried with hot air at 120°C for 4 hours and then placed in the spinning machine hopper and melt-spun.
The alloy of PLA or similar structure resin was prepared by weighing out the components shown in Tables 1 and 2, dry blending, and feeding them into the hopper of a twin-screw kneader, melt-kneading them at a resin temperature of 205°C, and producing pellets of the desired composition. The pellets obtained were dried and then used for spinning experiments. Carbodilite LA-1 was added as a stabilizer at 1.0 wt% to the PBS resin, PBS similar structure resin, or polylactic acid resin.

<Melt spinning>
For melt spinning, a spinning machine combining two vertical single-screw extruders (A and B) was used. When producing a single-layer fiber, the same material was charged into each of A and B and extruded, and when producing a double-layered fiber, different materials were charged into extruders A and B, so that fibers with different properties could be produced in the core-shell. Extruders A and B have a screw with a shaft diameter of 25 mm and a heating cylinder around it, and the molten resin is guided to the die through a flow path connected to the die. The die hole has 24 holes arranged in a circle, and each die hole has a double structure. The molten resin is guided from extruder A to the inner die hole and from extruder B to the outer die hole, and the core-shell molten resin is discharged in the form of a thread. The outer diameter of the die hole is 300 μm, and the inner diameter of the core part is 200 μm. The screw, cylinder, inner surface of the flow path through which the molten resin flows, and inner surface of the die of the extruder 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 taken up using five rollers, and can usually be drawn by successively increasing the rotation speed of each roller. In this case, it is effective to control the surface temperature of the rollers to 80-120°C. In this way, core-shell fibers with fiber diameters of 20-100 μm were produced. In the case of single-layer fibers, the same material was fed into extruders A and B and spun. In the case of multi-layer fibers, different materials were fed into extruders A and B. Multi-layer fibers with a core-sheath structure, in which the resin fed into A serves as the core and the resin fed into B serves as the sheath, and fiber diameters of 20-100 μm were produced.

The wound fiber was then heated again and stretched to produce fiber with a diameter of 0.5 to 20 μm. The fiber wound on the bobbin was then led to a stretching device, where the stretch ratio was adjusted by the difference between the speed of the rotating roll before the heating device for stretching and the rotation speed and diameter of the take-up roll after the heating device. The heating device used was an air heater at 100 to 140°C, where the fiber was passed through. Other effective methods include passing the fiber through a hot water tank or oil bath. A single heating device is sufficient, but multiple heating stages can also be used to increase the stretching degree to the desired level.

<Preparation of hybrid fabric>
The natural fibers such as silk, cotton, wool, and hemp used in combination with the single-layer or multi-layer fibers produced by spinning POM or POM alloy resin can be commercially available fibers. The fineness of the fibers is preferably approximately the same as that of the synthetic resin, since this will result in a smooth woven fabric.
Hybrid fabrics of POM or POM alloy resin and natural fibers can be manufactured by using each fiber for the warp or weft, or by twisting POM resin or POM alloy resin and natural fibers into a single thread and weaving it. The ratio of each fiber is adjusted so that synthetic fibers account for 30 wt% to 70 wt% of the entire fabric, and natural fibers such as silk, cotton, wool, and hemp account for 30 wt% to 70% of the entire fabric.

<Preparation of hybrid nonwoven fabric>
There are two methods for manufacturing nonwoven fabrics: melt spinning and melt blowing. The melt spinning method is suitable for precisely controlling the fiber diameter, whereas the melt blowing method allows nonwoven fabrics to be manufactured relatively inexpensively. However, the resin used in the melt blowing method must have high fluidity. In the melt spinning method, a core-shell double-structure fiber is melt spun using POM as the core, 50-100 wt% POM as the shell, and a resin composition containing PBS or a resin similar in structure to PBS with a melt flow rate (MFR) of 4-30 g/10 min, or 0-50 wt% PLA. The fiber is stretched to a size of 0.5-20 μm and wound on a bobbin. A bobbin wound with natural fiber of the desired fineness is prepared separately, and the POM core-shell fiber and natural fiber are introduced into a crimping machine in the desired ratio to produce raw cotton. Next, the raw cotton is carded to align the fiber orientation direction, then the fibers are entangled with each other using a needle punch device, and finally, the raw cotton is heated and compressed at 100° C. to 150° C. to produce a nonwoven fabric.
In the melt-blowing method, a resin composition consisting of a POM resin core, 50-100 wt% POM shell, and PBS or a resin similar in structure to PBS with a melt flow rate (MFR) of 4-30 g/10 min, or 0-50 wt% PLA is used, which is heated and melted in an extruder, blown out vigorously with compressed air as it is extruded from a nozzle, and collected in a collector made of wire mesh, and the resulting core-shell type POM fiber cotton and a separately prepared natural fiber cotton are introduced into a carding device in a desired ratio, the fibers are entangled to align the fiber orientation direction, and then the fibers are entangled with each other in a needle punch device to produce a nonwoven fabric. The resulting cotton is heat-compressed at 100°C to 150°C for 1 minute to produce a nonwoven fabric.

<Measuring method for texture>
The touch was measured by the bending resistance measurement method (drape coefficient method) of JIS L1096. First, five circular test pieces with a diameter of 254 mm were cut out from the hybrid woven fabric or nonwoven fabric, and a hole with a diameter of 10 mm was drilled in the center of each test piece. Next, the test piece was placed on the sample stage (diameter 127 mm) of the drape tester with the measurement side facing up, fixed with the sample presser, and the sample stage was vibrated up and down three times, and then left for one minute, and the drape shape area at that time was measured for the front and back of the sample piece. The drape coefficient was calculated by the following formula, and the average value of the front and back was calculated and rounded to three decimal places.

Df=Ad-S1/S2-S1

Df: drape coefficient Ad: vertical projection area of sample stage (drape shape area) (mm ² )
S1: Area of the sample stage (mm ² )
S2: Sample area (mm ² )
In the case of natural silk, the drape coefficient is about 0.2 to 0.4, and it feels soft and smooth. On the other hand, hybrid fabrics using silk and POM fibers in a 50:50 ratio for the warp and weft have a drape coefficient of 0.7 to 0.9, and feel firm and crisp. The drape coefficient is multiplied by 100 and expressed as a percentage.

<Evaluation of antibacterial properties of fibers>
The bacterial liquid absorption method is specified in JIS L1902. This method is a test that simulates the wearing of clothing, and evaluates the antibacterial effect by comparing the growth of bacteria on a standard cloth and a test cloth. The test bacteria used were (1) Staphylococcus aureus NBRC12732 for Staphylococcus aureus and (2) Escherichia coli NBRC3301 for Escherichia coli, and samples were sterilized in an autoclave before testing. The inoculum concentration (CFU/ml) was 1.5* ¹⁰⁵ . The antibacterial properties of the fiber were expressed as the antibacterial activity value [A]. This antibacterial activity value is calculated using formula (1).
A=(LogCb-LogCa)-(LogC2-LogC1) (1 formula)
Ca: Viable bacteria count on standard cloth Cb: Viable bacteria count on standard cloth after 18 hours of culture C1: Viable bacteria count on evaluation sample C2: Viable bacteria count on evaluation sample after 18 hours of culture

<Results>
Samples 1-a to 1-i in Table 1-1 used in the examples show hybrid woven fabrics of POM fiber with silk, cotton, wool, and linen, and Table 1-2 shows the results of antibacterial tests on these. The POM fiber used was either POM alone or POM alloy resin fiber. All of them have a high antibacterial activity value [A] of 5 or more. According to the JIS standard, an [A] of 2 or more is considered an antibacterial finished product, and according to the SEK standard, an [A] of 2.2 or more is considered an antibacterial finished product, and these products show antibacterial properties far superior to these values.

Examples, 2-a to 2-i in Table 2-1 show hybrid nonwoven fabrics of POM fiber and silk, cotton, wool, or hemp, and Table 2-2 shows the results of antibacterial tests for these. 2-a to 2-i in Table 2-1 show raw cotton produced by introducing the POM or POM alloy fiber of the present invention produced by the melt spinning method and natural fibers in a desired ratio into a crimping machine. Next, the raw cotton was aligned in the fiber orientation direction using a carding device, then the fibers were entangled with each other using a needle punch device, and finally nonwoven fabric was produced by heating and compressing at 100°C to 150°C. The results of antibacterial tests for nonwoven fabrics produced by blending silk, cotton, wool, and hemp yarns are shown in Table 2-2. All of them show high antibacterial activity values [A].
The POM alloy resin used for the shell contains 50-90 wt% POM resin, 10-45 wt% PBS or resin with a similar structure to PBS or PLA with a melt flow rate (MFR) of 4-30 g/10 min, and 0-5 wt% carbodiimide compound as a stabilizer. A commercially available POM resin was used for the core.

The sample woven fabrics used in the comparative examples are shown in Table 3-1, and the results of their antibacterial tests are shown in Table 3-2. Comparative examples 2-a to 2-f in Table 3-1 show hybrid fabrics in which POM or POM alloy fibers account for 30% or less of the entire fabric, and the results of their antibacterial tests are shown in Table 3-2. 3-g and 3-h in Table 3-1 used an alloy of POM and PBS resin for the weft, but when PBS with an MFR of 4 or less or 30 g/10 min or more was used, the fibers broke.
When the POM fiber is used at 70% or more of the natural fiber, the characteristics such as texture unique to the natural fiber are reduced, and the object of the present invention of imparting the antibacterial property of the polyacetal fiber while making use of the luxurious feel, dyeability, moisture retention, and reliability of the natural fiber, which is the object of the present invention, is not achieved. In order to maintain the luxurious feel and texture of the natural fiber, it is desirable to blend at least 30% or more of the natural fiber, preferably 40% or more. On the other hand, in order to express the antibacterial property of the woven fabric, the blending ratio of the POM fiber is at least 30% or more, preferably 50% or more. Taking into consideration the compatibility of the texture and antibacterial property, the desirable ratio is 50 to 70% of the synthetic fiber and 30 to 50% of the natural fiber.

Table 4-1 shows nonwoven fabrics produced by introducing POM resin or POM alloy fiber cotton produced by the melt-blowing method and natural fiber cotton in the desired ratio into a carding device, entangling the fibers to align the fiber orientation, and then entangling the fibers with a needle punch device. The resulting cotton was heat-compressed at 100°C to 150°C for 1 minute to produce nonwoven fabrics. Table 4-2 shows the results of antibacterial tests, but there is no antibacterial property when the POM or POM alloy fiber content is 30% or less. The feel of nonwoven fabrics is more difficult to judge than that of woven fabrics, and the difference in drape coefficient is smaller, but in consideration of achieving both antibacterial properties as with woven fabrics, 50 to 70% synthetic fiber and 30 to 50% natural fiber are preferable.

Claims (4)

1. An antimicrobial hybrid fabric comprising synthetic and natural fibers,
The synthetic fiber is obtained from an alloy (including POM alone) of 50 to 100 wt % polyacetal resin (hereinafter referred to as POM ) and 0 to 50 wt % biodegradable polyester resin ,
It is a single-layer or multi-layer synthetic fiber with a fiber diameter of 0.5 to 100 μm,
the natural fibers are silk, linen, cotton, or wool;
The synthetic fibers constitute 50 wt % to 70 wt % of the entire fabric , and
The antibacterial hybrid fabric , wherein the natural fibers constitute 30 wt % to 50 wt % of the entire fabric . 2. The hybrid fabric according to claim 1 , wherein the biodegradable polyester resin is one or more resins selected from the group consisting of polylactic acid (hereinafter referred to as PLA), polybutylene succinate (hereinafter referred to as PBS), polybutylene succinate adipate (PBSA), polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), polybutylene adipate-terephthalate (PBAT) , and polyhydroxybutyrate-hydroxyhexanoic acid ( PHBH ). The synthetic fiber has a core-sheath structure ,
The core is any one of a polyolefin resin , a polyester resin, a polyamide resin, an acrylic resin, a polyurethane resin, or a POM,
3. The hybrid fabric according to claim 1 or 2 , wherein the sheath is obtained from an alloy (including POM alone) of 50 to 100 wt % of POM and 0 to 50 wt % of a biodegradable polyester resin . The synthetic fiber is
The composite is obtained from an alloy of 50 to 90 wt % of the POM and 10 to 45 wt % of the biodegradable polyester resin,
The biodegradable polyester resin is PBS or a resin having a similar structure to PBS , or PLA,
The melt flow rate (MFR) of the PBS or a resin having a structure similar to that of the PBS is 4 to 30 g/10 min;
The antibacterial hybrid fabric according to claim 1, wherein the resin having a similar structure to PBS is one or more resins selected from the group consisting of polybutylene succinate adipate (PBSA), polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-hydroxyvalerate (PHBV), polybutylene adipate-terephthalate (PBAT), and polyhydroxybutyrate-hydroxyhexanoic acid (PHBH ) .