JP2007332476A - Nano fiber fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nano fiber fabric which applies various mercerizing treatments to a cotton material as a means for glossing the surface of the nano fiber fabric and has a beautiful gloss and a delicate hand in spite of fine unevenness on the surfaces of the nano fibers. <P>SOLUTION: This nano fiber woven fabric comprises the following nano fibers and mercerized cotton fibers. The nano fiber is composed of a thermoplastic polymer, has a number-average single fiber diameter of 1 to 200 nm, and the ratio of the area having a single fiber diameters of ≥200 nm is ≤3%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is an application of mercerization processing, which is a variety of cotton materials, as a means to give gloss to the surface of nanofiber fabrics. The present invention relates to a nanofiber fabric having a texture.

  Conventionally, fabrics using ultrafine fibers having a single yarn fineness of 1 dtex or less have been used for clothing and materials, and are widely known as a smooth texture and wiping cloth with good wiping properties.

  Conventionally, ultrafine fibers have a single fiber diameter of about 1 μm (1000 nm), but nanofibers with a single fiber diameter of about 100 nm have recently been made (see, for example, Patent Documents 1 and 2). Fabrics with an unprecedented texture have become possible due to the fineness of the nanofibers, but the fine irregularities on the nanofiber surface diffusely reflect visible light (380 to 770 nm). turn into.

On the other hand, mercerization treatment (silkette) that obtains silky luster by alkali treatment of cotton fibers in the state of yarn or fabric has been known, but for the treatment of fibers with a very large surface area such as nanofibers There was no knowledge so far.
JP 2004-162244 A JP 2004-244758 A

  The object of the present invention is to apply a mercerization process, which is a variety of cotton materials, as a means to give a gloss to the surface of the nanofiber fabric. The object is to provide a nanofiber fabric having a delicate texture.

In order to achieve the above object, the present invention adopts the following configuration. That is,
(1) A nanofiber fabric comprising the following nanofiber and mercerized cotton fiber.
Nanofiber: A fiber made of a thermoplastic polymer, having a number average single fiber diameter of 1 nm to 200 nm and an area ratio of single fiber diameter of 200 nm or more of 3% or less.

  (2) The nanofiber fabric according to (1), wherein the nanofiber is contained in an amount of 10% by weight or more and mercerized cotton fiber is contained in an amount of 20% by weight or more.

  (3) The nanofiber fabric according to (1) or (2), further comprising fibers made of a thermoplastic polymer having a diameter of 1000 nm to 250 μm.

  (4) The nanofiber fabric according to (3), wherein the thermoplastic polymer according to (3) comprises at least one selected from polyester, polyamide, and polyurethane.

  (5) A clothing article characterized by using the nanofiber fabric according to any one of (1) to (4).

  According to the present invention, it is possible to obtain a fabric having a beautiful luster and a delicate texture even though the nanofiber surface has fine irregularities.

  The present invention solves this problem by mercerizing a fabric containing polymer alloy fibers and cotton fibers, which are precursors of nanofibers, to obtain nanofiber fabrics containing the following nanofibers and mercerized cotton fibers. Thus, it has been clarified that a fabric suitable as clothing can be obtained.

  That is, the present invention provides a nanofiber precursor and a fabric containing cotton fibers by alkali treatment using a mercerizing machine of an existing facility, thereby providing gloss by forming nanofibers and modifying the surface. , To achieve cotton mercerization at the same time.

  The nanofiber fabric of the present invention includes the following nanofiber and mercerized cotton fiber.

  Nanofiber: A fiber made of a thermoplastic polymer, having a number average single fiber diameter of 1 nm to 200 nm and an area ratio of single fiber diameter of 200 nm or more of 3% or less.

  The nanofiber is preferably produced by using a polymer alloy fiber subjected to sea-island composite spinning as a precursor and removing the sea polymer to produce a nanofiber aggregate.

  That is, a polymer alloy melt obtained by alloying polymers having different solubility in two or more kinds of solvents is formed, and after spinning, it is solidified by cooling and fiberized. Then, if necessary, stretching and heat treatment are performed to obtain a polymer alloy fiber. Then, the nanofiber aggregate used in the present invention can be obtained by removing the easily soluble polymer (sea polymer) with a solvent and leaving the hardly soluble polymer (island polymer).

    Here, in the polymer alloy fiber that is a precursor of the nanofiber assembly, the easily soluble polymer forms a sea (matrix), the hardly soluble polymer forms an island (domain), and it is important to control the island size. . Here, the island size is obtained by observing the cross section of the polymer alloy fiber with a transmission electron microscope (TEM) and evaluating it in terms of diameter. Since the diameter of the nanofiber is substantially determined by the island size in the precursor, the island size distribution is designed according to the diameter distribution of the nanofiber.

  Specific guidelines for kneading depend on the polymer to be combined, but when using a kneading extruder, it is preferable to use a twin-screw extrusion kneader, and when using a static kneader, split it. The number is preferably 1 million or more. Moreover, in order to avoid blend spots and fluctuations in the blend ratio over time, it is preferable to measure each polymer independently and supply the polymers to the kneading apparatus independently. At this time, the polymer may be supplied separately as pellets, or may be supplied separately in a molten state. Two or more kinds of polymers may be supplied to the root of the extrusion kneader, or may be a side feed that supplies one component from the middle of the extrusion kneader. The blend ratio of the easily soluble polymer is preferably 10 to 90% by weight, and more preferably 30 to 70% by weight.

When designing a polymer combination, melt viscosity is important, and if the polymer forming the island is set lower, the island polymer is likely to be deformed by shearing force. From the viewpoint of However, if the island polymer is excessively low in viscosity, it tends to be seamed and the blend ratio with respect to the entire fiber cannot be increased. Therefore, the island polymer viscosity is preferably 1/10 or more of the sea polymer viscosity. In addition, the melt viscosity of the sea polymer may greatly affect the spinnability, and it is preferable to use a low viscosity polymer of 100 Pa · s or less as the sea polymer because the island polymer is easily dispersed. This can also significantly improve the spinnability. At this time, the melt viscosity is a value at a shear rate of 1216 sec ⁻¹ at the die surface temperature during spinning.

  When spinning the ultrafinely dispersed polymer alloy used in the present invention, the spinneret design is important, but the cooling condition of the yarn is also important. As described above, since the polymer alloy is a very unstable molten fluid, it is preferable to quickly cool and solidify after discharging from the die. For this reason, it is preferable that the distance from a nozzle | cap | die to the cooling start shall be 1-15 cm. Here, the start of cooling means a position where positive cooling of the yarn is started, but in the actual melt spinning apparatus, it is replaced with this at the upper end of the chimney.

The spun polymer alloy fiber is preferably subjected to stretching and heat treatment. However, the preheating temperature during stretching is higher than the glass transition temperature (T _g ) of the island polymer, so that the yarn unevenness can be reduced. It is possible and preferable.

  This production method makes it possible to obtain a polymer alloy fiber with a small dispersion of islands by ultrafine dispersion of island polymers by optimizing the combination of polymers and spinning / drawing conditions as described above. To do. In this way, by using polymer alloy fibers with small thread irregularities in the longitudinal direction of the yarn as a precursor, it is possible to obtain a nanofiber assembly with small variations in single yarn fineness not only in a certain section but also in any section in the longitudinal direction. is there.

  The nanofiber aggregate is obtained by eluting the readily soluble polymer, which is a sea polymer, with a solvent from the polymer alloy fibers obtained in this way. In this case, use an aqueous solution as the solvent. Is preferable from the viewpoint of reducing the environmental load, and it is particularly preferable to use an alkaline aqueous solution. For this reason, as the easily soluble polymer, a polymer that is alkali hydrolyzed, such as polyester, polycarbonate (PC), polylactic acid (PLA) or the like is preferable.

  On the other hand, the nanofiber aggregate remaining after removing the readily soluble polymer is composed of a hardly soluble thermoplastic polymer. For example, polyesters, polyamides, and thermoplastic polymers represented by polyolefins are preferable from the viewpoint of moldability. Among them, many polycondensation polymers represented by polyester and polyamide are more preferable because they have a high melting point. The melting point of the polymer is preferably 165 ° C. or higher because the heat resistance is good. For example, polylactic acid (PLA) is 170 ° C, PET is 255 ° C, and N6 is 220 ° C. The polymer may contain additives such as particles, flame retardant, antistatic agent and the like. In addition, other components may be copolymerized as long as the properties of the polymer are not impaired. However, as a hardly soluble polymer, the copolymerization rate is 5 mol% or 5 in order to maintain the inherent heat resistance and mechanical properties of the polymer. It is preferable that it is below wt%. The molecular weight of the polymer is preferably 10,000 to 500,000 in terms of weight average molecular weight from the viewpoint of fiber forming ability and mechanical properties. The relationship between the easily soluble polymer and the hardly soluble polymer is relative, and is determined by whether or not it is eluted under a specific solvent condition.

  The nanofiber referred to in the present invention refers to a fiber having a number average single fiber diameter of 1 nm to 200 nm and an area ratio of single fiber diameter of 200 nm or more of 3% or less. Those with a number average single fiber diameter of less than 1 nm are actually difficult to produce, and those with a number average single fiber diameter of over 200 nm, or those with a single fiber diameter of 200 nm or more exceeding 3% are unique to nanofibers. This is because it is difficult to feel the texture. Note that the area ratio of the single fiber diameter of 200 nm or more includes 0%.

  The average single fiber diameter of the nanofiber is evaluated as follows. That is, the nanofiber cross-sectional area calculated from the measured single fiber diameter of each nanofiber is defined as Si, and the sum is defined as the total area (S1 + S2 +... + Sn). The frequency (number) of nanofibers having the same cross-sectional area is counted, and the product divided by the total area is defined as the area ratio of the single fiber diameter. This corresponds to the area fraction of each single fiber with respect to the fiber assembly using nanofibers, and a component having a large fraction contributes greatly to the properties of the assembly using nanofibers.

  In the present invention, it is important to perform an alkali treatment on a fabric containing polymer alloy fibers and cotton fibers, which are precursors of nanofibers, using a mercerizing machine.

  When alkali treatment of nanofiber easy-dissolving polymer is performed with a mercerizing machine that applies tension to the vertical length of the fabric, the nanofiber aggregates are aligned and the grooves formed between adjacent nanofibers are also aligned. While regularity and glossiness are produced, if the alkali treatment is performed with insufficient tension by a conventional method, each nanofiber aggregate is randomly oriented and the irregularities of the fabric become irregular, and light Is diffusely reflected and no gloss is produced. In addition, the gloss of cotton fibers in the fabric is increased by the mercerization process, and the dyeability is improved.

  The mercerization treatment can be performed by applying a tension to the fabric for a certain period of time with the dried fabric immersed in a high-concentration alkaline solution.

  As the alkaline solution, sodium hydroxide, potassium hydroxide, lithium hydroxide or the like can be used, but it is economical to use sodium hydroxide. The concentration of the alkaline solution is preferably a 15 to 30% by weight aqueous solution. The temperature of the alkaline solution is preferably 0 to 30 ° C., particularly preferably 5 to 25 ° C., and is preferably controlled at a constant temperature and a constant concentration.

  The mercerizing process is not particularly limited, such as a clip mercerizing method, a chainless mercerizing method, or a cold batch method, which is processed in a roll shape, and the processing is performed while the fabric is kept in a tension state. The treatment time varies depending on the treatment method, and it is preferably 2 to 30 minutes for the spreading treatment and 2 to 12 hours for the roll.

  In order to completely remove the readily soluble polymer from the polymer alloy fiber, it is important to add an effect to the fabric so that the alkaline liquid can reach the inner layer of the polymer alloy fiber. The hydrolysis treatment is preferably used in combination with the mercerization treatment.

  The nanofiber fabric of the present invention may further contain fibers made of a thermoplastic polymer having a diameter of 1000 nm to 250 μm. The thermoplastic polymer here is preferably at least one selected from polyester, polyamide, and polyurethane. Polyester includes polyethylene terephthalate (PET), polypropylene terephthalate (PTT), polybutylene terephthalate (PBT), cationic dyeable PET, and the like. Polyamide includes nylon 6, nylon 6, 6, and the like. Different polyesters such as composite yarns of PET and PTT and composite yarns of polyester and polyamide are also preferably used. The cross-sectional shape of the fiber is not particularly limited, such as a circular shape, a polygonal shape, a dharma type, and a multileaf type, and may contain additives such as pigments and matting agents.

  The fabric composed of these fibers is not particularly limited, such as woven fabric, knitted fabric, and non-woven fabric, and there is no limitation on the structure.

  The ratio of the nanofiber and the mercerized cotton fiber in the nanofiber fabric is not particularly limited, but the nanofiber is preferably 10% by weight or more, more preferably 10% by weight to 60% by weight, and more preferably 20% by weight or more. If it is 50% by weight or less, the texture is more characteristic, which is more preferable. If it is less than 10% by weight, it is difficult to feel the characteristics of the nanofiber, and if it exceeds 60% by weight, the strength of the fabric becomes weak and it becomes impractical.

  Further, the mercerized cotton fiber is preferably 20% by weight or more, more preferably 20% by weight or more and 80% by weight or less, and further preferably 40% by weight or more and 70% by weight or less because it is easy to obtain a beautiful gloss. When it is less than 20% by weight, it is difficult to obtain gloss, and when it exceeds 80% by weight, it becomes difficult to feel the characteristics of the existing nanofibers.

  Using the nanofiber fabric of the present invention, various clothing items such as upper garments such as coats and jackets, bottoms such as pants and skirts, inner garments such as blouses and shirts, and accessories such as scarves, mufflers, and shoes can be produced.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, the measuring method in an Example used the following method.

A. Single fiber diameter based on the number average of nanofibers An ultra-thin section was cut in the cross-sectional direction of the nanofiber fibers, and the fiber cross-section was observed with a transmission electron microscope (TEM: H-7100FA type, manufactured by Hitachi, Ltd.). Nylon was metal dyed with phosphotungstic acid. The single fiber diameter was calculated for the photograph obtained by using image processing software (WINROOF), and a simple average value thereof was obtained. This was defined as “number average single fiber diameter”. At this time, the average number of nanofibers used in the measurement was the diameter of 300 or more single fibers randomly extracted in the same cross section. When the contrast was low, metal staining was performed.

B. Single fiber diameter variation of nanofiber The single fiber diameter variation of nanofiber is evaluated as follows. That is, using the data used when calculating the single fiber diameter by the above-mentioned number average, the cross-sectional area calculated from the single fiber diameter of each nanofiber is Si, and the total is the total area (S1 + S2 +... + Sn). Further, the frequency (number) of nanofibers having the same single fiber diameter is counted, and the product divided by the total area is defined as the area ratio of the single fiber direct system.

Reference example (production of N6 / PLA polymer alloy fiber)
N6 (nylon 6) having a melt viscosity of 57 Pa · s (240 ° C., shear rate of 2432 sec ⁻¹ ), a weight average molecular weight of 120,000, a melt viscosity of 30 Pa · s (240 ° C., 2432 sec ⁻¹ ), and a poly L lactic acid having a melting point of 170 ° C. With an optical purity of 99.5% or higher), a blending ratio of N6 of 40% by weight, a blending ratio of poly-L lactic acid of 60% by weight, a kneading temperature of 220 ° C., and melt kneading under the following conditions to obtain a polymer alloy chip It was. In addition, the weight average molecular weight of polylactic acid (PLA) was calculated | required as follows. THF (tetrohydrofuran) was mixed with the sample chloroform solution to obtain a measurement solution. This was measured at 25 ° C. using water permeation gel permeation chromatography (GPC) Waters 2690, and the weight average molecular weight was determined in terms of polystyrene. Further, the melt viscosity of this poly L lactic acid at 215 ° C. and 1216 sec ⁻¹ was 86 Pa · s. The kneading conditions at this time were as follows.
Screw type Same direction complete meshing type Double thread screw Diameter 37mm, effective length 1670mm, L / D = 45.1
The kneading part length is 28% of the effective screw length
The kneading part was located on the discharge side from 1/3 of the effective screw length.
Polymer supply with three backflow parts in the middle N6 and copolymerized PET were weighed separately and fed separately to the kneader.
260 ° C
Two vents The polymer alloy chip was melted at a melting temperature of 230 ° C and led to a spin block having a spinning temperature of 230 ° C. The polymer alloy melt was filtered with a metal nonwoven fabric having a limit filtration diameter of 15 μm, and then melt-spun from the die 5 with a die surface temperature of 215 ° C. The distance from the base lower surface to the cooling start point was 10 cm. The discharged yarn is cooled and solidified with a cooling air of 20 ° C. over 1 m, and is supplied by an oil supply guide installed 1.8 m below the base 5, and then passed through the unheated first take-up roller and second take-up roller. Was wound up at 3000 m / min. At this time, a normal spinneret having a cap diameter of 0.30 mm and a hole length of 0.75 mm was used as the base, but almost no ballus phenomenon was observed, the spinnability was good, and the yarn breakage was 0 times with 1 t spinning. Met. As a result, a 100 dtex, 36 filament, highly oriented undrawn yarn was obtained. The strength was 2.2 cN / dtex, the elongation was 110%, and U% = 1.1%, which was extremely excellent as a highly oriented undrawn yarn. It was a thing. In particular, as the ballast was greatly reduced, the yarn spots were greatly improved.

  This highly oriented undrawn yarn was drawn and heat-treated at a preheating roller temperature of 90 ° C., a draw ratio of 1.44 times, and a heat setting roller temperature of 130 ° C. The obtained drawn yarn was 70 dtex, 36 filaments, and showed excellent properties of strength 2.6 cN / dtex, elongation 43%, boiling water shrinkage 9%, U% = 0.9%.

  When the cross section of the obtained polymer alloy fiber was observed by TEM, PLA showed a sea-island structure where the sea (thin part) and N6 were islands (dense part), and the number average diameter of the island N6 was 95 nm (CV = 25 %), And polymer alloy fibers in which N6 was nano-sized and uniformly dispersed were obtained.

Example 1
Using a polymer alloy fiber obtained in the reference example as a warp yarn and a cotton fiber (60th) as a weft yarn, a woven fabric of 5 satin and 5 satin fabrics was woven. This woven fabric was scoured, bleached, and dried according to a conventional method, and then mercerized by a clip mercerization method.
A water tank was set at 20 ° C. to prepare a 25% by weight aqueous sodium hydroxide solution. The dough was continuously treated in a tension state and immersed in an alkaline bath for a total of 5 minutes. Subsequently, it was washed with water to remove the alkali on the dough and dried, and then an intermediate set was performed with a pin tenter.
Next, the dough is charged with a liquid dyeing machine, sodium hydroxide is added to a 3% solution, the temperature is raised to 95 ° C., and the dough is run for 30 minutes, and PLA is a sea polymer of polymer alloy fibers. More than 99% of the fabric was removed from the fabric. The dough was taken out after washing with hot water and sufficiently removing the PLA residual. After spreading the dough, a finishing set was performed with a pin tenter to obtain a nanofiber fabric.
When nanofibers were taken out from the warp yarn of this nanofiber fabric and observed with a TEM, it was as shown in Table 1, and a fabric having a beautiful luster and a soft peach-like texture was obtained.

Example 2
A polymer alloy fiber obtained in the reference example was used as a warp yarn, a core spun yarn fiber (45th) in which a polyurethane fiber was used as a core and the outside was covered with a cotton fiber was used as a horizontal yarn, and a 1/2 twill fabric was woven. This fabric was treated in the same manner as in Example 1 to obtain a nanofiber fabric.
When nanofibers were taken out from the warp yarns of the nanofiber fabric and observed with a TEM, a stretch fabric having both beautiful luster and delicate touch was obtained as shown in Table 1.

Example 3
Cotton fibers (45th) were used as warp yarns, polymer alloy fibers obtained in the reference examples were used as weft yarns, and plain fabrics were woven. This fabric was scoured, bleached and dried according to a conventional method, and then mercerized by a cold batch method.
A 20% by weight sodium hydroxide aqueous solution was applied to the woven fabric by pad treatment, wound into a roll while applying a constant tension to the stainless steel core, and the entire roll was sealed with a vinyl sheet and left in a room at 15 ° C. for 8 hours. Thereafter, the alkali was removed by washing with water and dried, followed by intermediate setting with a pin tenter.
Next, the dough was put into a liquid dyeing machine, the same treatment as in Example 1 was performed, the sea polymer of the polymer alloy fiber was removed, and finishing set was performed to obtain a nanofiber fabric.
When the weft of the nanofiber fabric was taken out and observed with a TEM, it was as shown in Table 1, and a fabric having a beautiful luster and peach-like texture was obtained.

Example 4
A flat yarn in which cotton fibers (60th count) are warp yarns, and polymer alloy fibers obtained in the reference example and cationic dyeable polyester (“LOC-II”, 84 dtex, 36 filaments manufactured by Toray Industries, Inc.) are alternately used as weft yarns. Woven fabric. This fabric was scoured, bleached and dried in the same manner as in Example 1, and then mercerized by the chainless mercerization method.
A water bath was set at 20 ° C. to prepare a 25% by weight sodium hydroxide aqueous solution, and the dough was continuously treated in a tension state, and immersed in an alkaline bath for a total of 10 minutes. Subsequently, it was washed with water to remove the alkali on the dough and dried, and then an intermediate set was performed with a pin tenter.
Next, the dough is charged in a liquid dyeing machine and the same treatment as in Example 1 is performed to remove the sea polymer of the polymer alloy fiber, followed by cationic dyeing and finishing set by a conventional method, and a horizontal stripe nanofiber. I got a fabric. ,
When the nanofiber of the weft of this nanofiber fabric was taken out and observed by TEM, it was as shown in Table 1, and a fabric having a beautiful gloss and a delicate touch was obtained.

Comparative Example 1
The woven fabric woven in Example 1 was subjected to desizing, bleaching, drying and intermediate setting, and then put into a liquid dyeing machine. This nanofiber fabric obtained by adding 3% by weight of an aqueous sodium hydroxide solution, raising the temperature to 95 ° C., running the fabric for 60 minutes, and removing the sea polymer from the polymer alloy fibers to obtain a nanofiber fabric by finishing setting. When nanofibers were taken out of the warp yarns and observed by TEM, the results were as shown in Table 1. However, the woven fabric had a glossy and rough surface, the texture was stiff, and the nanofiber was not delicate.

Claims (5)

A nanofiber fabric comprising the following nanofibers and mercerized cotton fibers.
Nanofiber: A fiber made of a thermoplastic polymer, having a number average single fiber diameter of 1 nm to 200 nm and an area ratio of single fiber diameter of 200 nm or more of 3% or less. The nanofiber fabric according to claim 1, wherein the nanofiber fabric contains 10% by weight or more of nanofibers and 20% by weight or more of mercerized cotton fibers. The nanofiber fabric according to claim 1 or 2, further comprising fibers made of a thermoplastic polymer having a diameter of 1000 nm or more and 250 µm or less. The nanofiber fabric according to claim 3, wherein the thermoplastic polymer according to claim 3 is made of at least one selected from polyester, polyamide, and polyurethane. An article of clothing using the nanofiber fabric according to any one of claims 1 to 4.