JP2014189934A - Nanofiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nanofiber including scarce gelled impurities within the fiber interior and having an excellent abrasion resistance.SOLUTION: The provided nanofiber is obtained by filtering an already dried chip scheduled to be used for spinning and a body of washing water including a chip powder through a made-of-stainless-steel mesh having apertures commensurate with 50-99% of the chip size so as to separate the chip alone, by separating the chip powder and washing water through a filter having 10 μm apertures so as to manage the chip powder content within the resin chip at 0.01-1% in terms of weight ratio, and by subjecting the resulting thermoplastic resin having an adjusted gel content of 0.1-3.0% to a sea-island-type composite spinning method so as to realize single fiber diameters of 50-1000 nm.

Description

  The present invention relates to a nanofiber having a small amount of gel-like foreign matter contained in a fiber and excellent in wear resistance.

  Synthetic fibers such as polyester and polyamide are widely used not only for general apparel but also for industrial materials because they are easy to design yarns of fiber diameter, shape, and physical properties and are excellent in dimensional stability. It has been.

  In recent years, it has begun to be used for special and new applications for existing synthetic fibers, such as functional clothing such as heat insulation / heat-generating clothing and compression wear, low pressure loss high dust collection filters, screens for printing on electronic circuit boards, etc. The expectations for the creation and advancement of high-performance fibers are growing.

  As one of high-performance fibers, development of ultra-fine fibers (nanofibers) having a fiber diameter of 1000 nm or less is being promoted. Features of nanofibers include increased flexibility (soft feeling) by scaling down the fiber diameter, increased specific surface area, and refined voids in the yarn, resulting in high water absorption and high moisture absorption, high Utilizing its friction characteristics and good wiping performance, it has been applied to sports materials, industrial filters, and precision polishing cloths for hard disks.

  An electrospinning (ESP) method has been proposed as one method for producing nanofibers. The ESP method is a production method (see, for example, Patent Document 1) in which nanofibers are extracted by discharging them into an electric field while applying a voltage to a solution containing a resin as a solute. In addition to being limited to non-woven fabrics such as filters, it is also difficult to control the fiber diameter and arrangement, so that it is not suitable for clothing applications.

  As another method, a method for producing a bundle-like nanofiber by combining a polymer blend technique and a polymer dissolution removal technique has been proposed (for example, see Patent Document 2). Although the nanofiber itself manufactured by the technique of Patent Document 2 is a short fiber, it can be made into a fabric product such as a woven fabric or a knitted fabric as a long fiber because it forms an aggregate. However, it is difficult to control the single fiber diameter of nanofibers and aggregates, and because of the aggregates of short fibers, the strength is low, and the abrasion resistance is low due to fibrillation and detachment, making it impractical as a fabric product. There was a problem.

  As a means of developing long-fiber nanofibers that can be applied to woven fabrics and knitted fabrics, overcoming the inferior durability and quality problems that have been a problem with the above technologies, in recent years, the deepening of sea-island type composite spinning technology has been actively conducted. (For example, see Patent Documents 3 and 4). However, the development of sea-island type composite fibers exemplified in the prior art represented by Patent Documents 3 and 4 is specialized only in solving the problem of how to reduce the island component diameter.

  In the melt spinning process, since a high-temperature molten polymer passes through a pipe or a spinneret, thermal degradation of the polymer is inevitable although it is large or small. Conventionally, nanofibers manufactured under the same quality control are not practical for use in abrasive cloths for precision instruments that require precision and dust-freeness.

JP 2007-303015 (Claims) JP 2004-162244 A (Claims) Japanese Patent Application Laid-Open No. 2007-100343 (Claims) JP 2011-208326 A (Claims)

  The object of the present invention is to overcome the problems of the prior art described above, control the thermal history of the melt spinning process of the resulting nanofiber, reduce the amount of gel-like foreign matter contained in the fiber, and have excellent wear resistance. To provide fiber.

In order to solve the above-described problems, the present invention has the following configuration. That is,
Nanofibers having an average single fiber diameter of 50 to 1000 nm and a gelling rate of 0.1 to 3.0% made of a thermoplastic resin.

  According to the present invention, it is possible to obtain nanofibers with a small amount of gel-like foreign matter contained in the fiber and excellent wear resistance.

  Examples of the thermoplastic resin constituting the nanofiber of the present invention include polyester-based, polyamide-based, and polyolefin-based resins. For example, polyester resins include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid. In addition to polyesters containing aromatic dicarboxylic acids such as acids as the main acid component and at least one glycol selected from ethylene glycol, trimethylene glycol, tetramethylene glycol, and alkylene glycol components as the main glycol component, polylactic acid can also be targeted. . Furthermore, a copolyester obtained by copolymerizing a third component other than the above can also be used. In particular, polyesters containing 5-sodium sulfoisophthalic acid or polyethylene glycol as a copolymer component are highly soluble and degradable in an aqueous alkali solution, and are therefore used as sea component polymers for sea-island composite fibers suitable for obtaining nanofibers. It is suitable for.

  The polyamide-based resin includes polyamides mainly composed of amino acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and paraaminomethylbenzoic acid, and lactams such as ε-caprolactam and ω-laurolactam. In addition, succinic acid, glutaric acid, adipic acid, sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, octadecane The main acid component is aliphatic dicarboxylic acid such as diacid or aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, etc., tetramethylenediamine, hexamethylenediamine, 1,5-pentanediamine, 2-methylpenta Methylenediamine, noname Copolymer polyamides containing tylenediamine, undecamethylenediamine, dodecamethylenediamine or the like as a diamine component can also be used. Furthermore, a modified polyamide obtained by copolymerizing a third component other than the above can also be used.

  Polyolefin resins are targeted for polyethylene and polypropylene, and polystyrene is also targeted for thermoplastic resins.

  In the above thermoplastic resin, inorganic fine particles, organic compounds, and carbon black may be added as necessary as a matting agent such as titanium oxide, a flame retardant, a lubricant, an antioxidant, a heat-resistant agent, and a color pigment. it can.

  The average single fiber diameter of the nanofiber of the present invention is 50 to 1000 nm. By making the nanofiber single fiber diameter 1000 nm or less, softness and scratch properties (low attack) that cannot be achieved with existing ultrafine fiber (including microfiber) products can be obtained, and the specific surface area can be increased. The high frictional force and high wiping property associated with the improvement of the adsorptivity due to the increase in the porosity are achieved. In order to obtain a more excellent scratch property and wiping effect, the single fiber diameter is preferably 900 nm or less, more preferably 800 nm or less, and still more preferably 750 nm or less. The smaller the single fiber diameter of the nanofiber, the better. However, since the breaking strength is reduced with the thinning and becomes unsuitable for actual use, the limit is about 50 nm.

  The gelation rate of the nanofiber of the present invention is 0.1 to 3.0%. By setting the gelation rate to 3.0% or less, nanofibers excellent in high-order workability and wear resistance can be obtained. In order to obtain more excellent wear resistance, the gelation rate is preferably 2.0% or less, more preferably 1.5% or less, and still more preferably 1.0% or less. The smaller the gelation rate, the better. However, in the melt spinning process, the thermal history associated with the heat melting of the resin is unavoidable, so about 0.1% is the limit.

  As a method for producing the nanofiber of the present invention, it is preferable to apply a sea-island type composite spinning method. By applying the sea-island type composite spinning method, the amount of polymer discharged per single hole of the die can be increased, so that the spinning performance is stable even when spinning ultrafine fibers. The base used for the sea-island type composite spinning may have any known internal structure as long as it can spin ultrafine fibers of 1000 nm or less stably in quality and operation. The cross-sectional shape of the island component can be arbitrarily selected and adopted according to the use and required characteristics such as polygonal, hollow, Y-type, X-type, C-type, saddle-type, and elliptical shape in addition to the round cross-section.

  A sea-island type composite fiber suitable for obtaining the nanofiber of the present invention comprises a sea component which is a readily soluble resin with respect to a solubilizer and an island component of a hardly soluble resin. It is preferable that the island component and the sea component are produced by a combination having as large a difference in dissolution rate as possible when the dissolving agent is processed. A preferable range of the dissolution rate difference is 5 to 300 times the dissolution rate of the sea component with respect to the island component. However, this is not the case when the island component polymer does not dissolve in the dissolving agent at all. By making the difference in dissolution rate 5 to 300 times, the dissolution and removal of the sea component is executed smoothly, and the difference in the contact time of the island component solubilizer at the surface / core of the sea island single yarn is reduced, so the fiber diameter variation is small. A group of nanofibers can be obtained. A more preferable range of the difference in dissolution rate is 20 to 280 times.

  Examples of preferred combinations of island components and sea components used for the sea-island type composite fibers are listed below. When the dissolving agent is an alkaline aqueous solution, the sea component is a copolyester resin and the island component is a homopolyester resin, the sea component is an aliphatic polyester resin and the island component is a polyamide resin, and the sea component is an aliphatic polyester resin and the island component. Polyester resin made of aromatic dicarboxylic acid. When the dissolving agent is an acid aqueous solution, the sea component is a polyamide-based resin and the island component is a polyester-based resin. When the dissolving agent is an organic solvent such as toluene or trichlorethylene, the sea component is polystyrene and the island component is a polyester resin, the sea component is polystyrene and the island component is a polyamide resin. In addition, since polyvinyl alcohol is soluble in hot water, it is suitable for use as a sea component polymer of a sea-island composite fiber suitable for obtaining nanofibers. In addition, in order to perform a smooth melting process, you may perform the reprocessing and the pre-process by another solvent.

  A blend polymer may be used for the island component constituting the nanofiber. If the blend components are soluble in the solubilizer, nanofibers with voids or slits on the surface can be obtained, and in addition to further improving the adsorptivity by increasing the surface area, providing water absorption and water retention Can also be expected.

  The sea-island type composite fiber suitable for obtaining the nanofiber of the present invention can be obtained by a melt spinning method, but at the time immediately before melting the island component polymer, the chip powder content in the resin chip of the island component polymer It is important to manage the content of 0.01 to 1% by weight.

Here, the measuring method of chip powder content rate is demonstrated. First, an appropriate amount of the dried chips to be used for spinning is extracted immediately before melting and washed in pure water. Only the chip is separated by filtering the chip and the washing water containing the chip powder with a stainless mesh having an opening of 50 to 99% of the chip size, and further the chip powder and the washing water are separated with a filter having an opening of 10 μm. The weight (W1) of the separated chip and the weight (W2) of the chip powder were measured, and the chip powder content was measured by substituting into the following formula.
Chip powder content = (W2 × 100) / (W1 + W2)
W1: Weight of only chip (g), W2: Weight of chip powder separated from extracted chip (g)
Chip powder has a higher crystallinity than the resin chip itself and tends to have a high melting point. Therefore, the chip powder mixed in the process is not completely melted and is contained in the fiber as a gel-like foreign substance. It is important to eliminate the chip powder from the spinning process because the part where the gel-like foreign material is present is inferior in strength to the part consisting only of the resin, which causes fiber wear such as yarn breakage, fluffing, and fiber loss. . In addition, when chip powder larger than the fiber diameter is mixed, it exists like a node in the fiber, and the fiber diameter uniformity in the fiber longitudinal direction cannot be maintained. It also becomes a factor inferior in performance (hereinafter referred to as wiping property). By making the chip powder content 1% or less, nanofibers excellent in wear resistance can be obtained, but it is more preferably 0.8% or less, and still more preferably 0.5% or less. The smaller the amount of chip powder, the better. However, since complete chip powder removal is substantially difficult, 0.01% is the limit.

  The technique for managing the chip powder content to 1% or less is described below.

  First, an undried chip is washed with pure water, and a process of removing chip cut waste generated in the chip manufacturing process is performed. If the amount of pure water used is too small, the chips rub against each other and become a source of new powder, so the amount of pure water is preferably equal to or greater than the apparent volume of the chips. In addition, since ultrasonic treatment can effectively remove even fine chip waste, it is preferably introduced into the cleaning process.

  Subsequently, the cleaning water containing the chips is filtered through a filter, and only the chips are scooped up. The opening of the filter is not limited as long as the chip can be captured, and a stainless steel mesh having an opening of 50 to 99% of the chip size is preferably used. By setting it to 50% or more, it is possible to prevent even the waste adhering to the undried chip from being trapped, and by setting it to 99% or less, it is possible to prevent the chip itself from passing through the filter.

  The undried chips washed with the above method are preferably dried with a stationary drier. By drying with a stationary drier, it is possible to suppress the generation of chip powder due to friction between chips and contact with the inner wall of the dryer. The drying conditions to be applied are performed using known techniques suitable for the polymer characteristics.

  When supplying the dry chips obtained by the above method to the spinning machine, the path (pipe length) from the chip supply unit to the melt spinning machine is to minimize friction between the chips and contact with the tube wall. It is preferable to make it as short as possible. Specifically, in the case of a pressure melter type melt spinning machine, the tip is supplied from a position within 5 m of the pipe length from the hot plate, and in the case of an extruder type melt spinning machine, the length of the pipe is introduced from the tip introduction part to the screw. The chip is supplied from within 5m. By the above method, it becomes possible to manage the chip powder content in the resin chip at the time immediately before melting to 1% or less.

  In the present invention, the sea / island composite ratio (volume ratio) of the sea-island type composite fiber is preferably in the range of 10/90 to 50/50. By setting the sea component to 10% or more, it is possible to prevent the island components from being fused to each other. Therefore, it is possible to obtain nanofibers that have excellent seawater removal properties and can withstand actual use. Further, when the sea component is 50% or less, it is possible to shorten the sea component dissolution and removal time, and it is possible to suppress an excessive volume loss of the sea-island composite fiber. A more preferable range of the sea / island composite ratio is 15/85 to 40/60.

  A sea-island type composite fiber suitable for obtaining the nanofiber of the present invention can be produced, for example, by the following method. That is, using the island component and the sea component melted polymer obtained by the above method, from which the chip powder has been sufficiently removed, the composite polymer discharged through the sea-island type composite spinning die is cooled and solidified and wound up. To fiberize.

  The spinning temperature is set in the range of +10 to + 40 ° C. from the polymer melting point on the high melting point side. By setting the polymer melting point to + 10 ° C or higher than the polymer melting point on the high melting point side, the polymer is prevented from solidifying and clogging in the spinning pipe, and by suppressing it to + 40 ° C or lower, excessive thermal deterioration of the polymer is suppressed. Can do. The residence time in the spinning machine from the melting of the island component polymer to the discharge of the die is preferably within 30 minutes.

Regarding the winding method, in addition to the two-step method in which the discharged polymer is once wound as an undrawn yarn and then drawn, any process such as the direct spinning drawing method or the high-speed spinning method in which spinning and drawing steps are continuously performed is used. Can also be manufactured. Although it may be a step of drawing after winding as a semi-drawn yarn, in any case, the spinning draft represented by the following formula is preferably in the range of 50 to 400.
Spinning draft = Vs / V0
Vs: Spinning speed (m / min), V0: Single hole discharge linear speed (m / min)
By setting the spinning draft to 50 or more, it is possible to prevent the polymer flow discharged from the die hole from staying directly under the die for a long time and to suppress the contamination of the die surface. Further, by setting the spinning draft to 400 or less, it becomes possible to suppress yarn breakage due to over tension, and sea-island type composite fibers can be produced stably in operation. A more preferable range of the spinning draft is 100 to 350.

  The nanofibers of the present invention can be obtained by eluting the sea component polymer from the sea-island type composite fiber obtained by the above method using a solubilizer suitable for the combination of the sea component and the island component polymer.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the following method was used for each characteristic value in an Example.

(1) Intrinsic viscosity of polyester (IV)
Ηr of the definition formula is obtained by dissolving 0.8 g of a sample polymer in 10 mL of O-chlorophenol (OCP) having a purity of 98% or more, and obtaining the relative viscosity ηr by the following formula using an Ostwald viscometer at a temperature of 25 ° C. The intrinsic viscosity (IV) was calculated.
ηr = η / η0 = (t × d) / (t0 × d0)
Intrinsic viscosity (IV) = 0.0242 ηr + 0.2634
η: viscosity of polymer solution η0: viscosity of OCP t: drop time of solution (seconds)
d: density of the solution (g / cm ³ )
t0: OCP fall time (seconds)
d0: OCP density (g / cm ³ ).

(2) Relative viscosity of polyamide (ηr)
For the polyamide-based resin, 1 g of the sample polymer was dissolved in 100 mL of 98% concentrated sulfuric acid, and the relative viscosity ηr was determined by the following equation using an Ostwald viscometer at a temperature of 25 ° C.
ηr = T1 / T2
T1: Fall time (second) of solution, T2: Fall time (second) of concentrated sulfuric acid.

(3) Melt mass flow rate (MFR)
The MFR (g / 10 min) of polystyrene was measured according to JIS K 7210 (1999).

(4) Average single fiber diameter The fiber group was observed with a scanning electron microscope (SEM: Hitachi-S-3000N). 50 single fibers were randomly selected from the yarn, and the average fiber diameter was calculated from the measured values.

(5) Gelation rate measurement A solubilizer for the resin constituting the nanofiber is appropriately selected, and the nanofiber is completely dissolved in the solubilizer. Subsequently, the solution is filtered through a filter having an opening of 10 μm, and the amount of captured matter on the filter is weighed. The value represented by the following formula was defined as the gelation rate.

Gelation rate = (weight of captured matter (g) / fiber weight before dissolution treatment (g)) × 100
(6) Fineness (dtex)
In the case of a sea-island type composite fiber, a value obtained by scraping 100 m of the yarn and multiplying the mass (g) of the skein by 100 was defined as the fineness. About the fineness of the nanofiber, it was set as the fineness using the value represented by the following formula.
Fineness (dtex) of sea-island type composite fiber × (100−weight loss rate (%)) / 100
(7) Strength (cN / dtex)
The strength of the nanofiber was measured with Tensilon UCT-100 manufactured by Orientec in accordance with JIS L 1013 (2010). Measurement was performed three times in succession, and the average value was defined as the intensity.

(8) Abrasion resistance (forced abrasion test)
A nanofiber group appropriately combined to have a total fineness of about 200 dtex is applied with a 3 mm diameter satin metal rod (made of stainless steel) so that each bend is 35 °, and the yarn tension is 340 mm from the satin metal rod. Grasping was performed at 0 g / dtex, and a reciprocating motion of 5 minutes was given at a stroke length of 30 mm and a speed of 600 times / min. Thereafter, the surface condition of the yarn was observed with the naked eye and a digital microscope (VHX-100 manufactured by KEYENCE), and the abrasion resistance of the nanofiber was evaluated according to the following criteria, and four or more points were accepted.
5 points: No fluff due to abrasion.
4 points: Fluff due to rubbing, but cannot be confirmed with the naked eye.
3 points: There is fluff that can be confirmed with the naked eye.
2 points: Although the yarn is not broken, a partial disconnection can be confirmed.
1 point: The yarn was broken.

(9) Pilling property Using a group of nanofibers appropriately combined so that the total fineness is about 200 dtex, a warp density of 92 / 2.54 cm and a weft density of 79 / 2.54 cm were prepared as test cloths. It was. The method A described in JIS L 1076 (2012) was applied mutatis mutandis, and the pilling property of the test cloth was measured.

(10) Scratch property A test cloth prepared according to the same method as in (9) above was used as a tape having a width of 4 cm, and the aluminum substrate on which the diamond abrasive slurry was dropped was polished for 20 seconds at a running speed of 5 cm / min. With respect to the polished substrate surface, a groove having a depth of 3 nm or more was scratched using an optical surface analyzer. Scratches were measured on both surfaces of five substrates, and the scratch property was evaluated in three stages based on the average value of the numbers. The scratch property is better when the value is smaller.
◯: Less than 40 points ◯: 40 points or more and less than 80 points X: 80 points or more

(11) Wiping property A sample obtained by uniformly applying liquid paraffin mixed with 10% by weight of carbon black on a glass plate is used as a wiping sample, and a test cloth obtained by the same method as in the above (9) is used as a friction element. The liquid paraffin was wiped by pasting and sliding at a surface pressure of 20 g / cm ² and a running speed of 10 cm / min. Using a 2 cm × 2 cm field of view including the liquid paraffin coating part as an analysis range, the residual ratio of liquid paraffin before and after wiping (the following formula) was measured, and a residual ratio of 15% or less was accepted.
Residual rate (%) = (residual liquid paraffin area after wiping (cm ² ) / 4 cm ² ) × 100
Example 1
As an island component polymer, IV = 0.71 containing 0.1% by weight of titanium dioxide, polyethylene terephthalate having a melting point of 253 ° C., and as a sea component polymer, 7.3 wt% of 5-sodium sulfoisophthalic acid was co-used with respect to the total amount of polyethylene terephthalate. The alkali-soluble copolymer polyethylene terephthalate having IV = 0.55 contained as a polymerization component was obtained in the form of chips. The difference between the dissolution rates of both polymers in the aqueous alkali solution was 40 times. As a pre-spinning stage, the island component chips were washed in a container to which 2 equivalents of pure water was added to the apparent volume of the island component chips, and subsequently stainless steel having an opening of 90% of the island component chip size. The mesh was passed through, and only the island component chips were collected to remove chip waste. Next, the undried island component chips were dried by a known method in a stationary dryer, and the obtained dried chips were supplied from 4 m above the pressure melter hot plate. The chip powder content of the obtained dry chip was 0.4%.

  Both the island component chip and the sea component chip were melted at 290 ° C. using a pressure melter and weighed with a pump. Both components were allowed to flow into the die while maintaining the spinning temperature at 290 ° C. The composite ratio was sea / island = 30/70. Each polymer flowed into the sea island type composite spinneret with 127 islands and holes 112 (number of islands × number of single yarns = 14224) was merged inside the base, and the island component polymer was included in the sea component polymer. A composite form was formed and discharged from the die. The residence time from melting to discharging of the island component polymer was 10 minutes. The yarn discharged from the die was cooled by an air-cooling device, applied with an oil agent, wound by a winder at a speed of 1500 m / min so that the spinning draft was 219, and wound as an undrawn yarn of 192 dtex-112 filament. In the microscopic observation of the undrawn yarn obtained by this process, the island component was not fused.

  Subsequently, the obtained undrawn yarn is fed to a drawing device at a speed of 300 m / min, drawn to a drawing temperature of 92 ° C. and a residual elongation of about 20 to 40%, and then heat-set at 130 ° C. The drawn yarn of 75 dtex-112 filament was obtained stably through the drawing process.

  The obtained sea-island type composite fiber was pretreated by immersing it in a 1 g / L maleic acid aqueous solution at 120 ° C. for 30 minutes, and then the sea component was adjusted so that the weight loss rate was 30% with a 1% sodium hydroxide aqueous solution at 80 ° C. The polymer was dissolved and removed. The obtained nanofibers had an average single fiber diameter of 580 nm and a gelation rate of 1.0%.

  Table 1 shows the evaluation results obtained using the obtained nanofibers. The strength of the nanofiber was 3.5 cN / dtex, which was sufficient for practical use, and the fabric made of the nanofiber was excellent in wear resistance, pilling property, scratch property, and wiping property.

Example 2
In the sea-island composite fiber for obtaining nanofibers, the island component polymer is nylon 66 with ηr = 2.8, the sea component polymer is MFR = 5.5 g / 10 min polystyrene (“Toyostyrene” H- Nanofibers were obtained by the same method as in Example 1 except that the procedure was changed to 45). The gelation rate of the nanofiber obtained in Example 2 was 1.2%. The evaluation results obtained using the obtained nanofibers are as shown in Table 1. As in Example 1, excellent wear resistance, pilling properties, and wiping properties were obtained.

Example 3
In the sea-island type composite fiber for obtaining the nanofiber, Example 1 was changed except that the island component polymer was changed to poly-L-lactic acid with IV = 0.59 and the sea component polymer was changed to nylon 66 with ηr = 2.8. Nanofibers were obtained by the same method. The gelation rate of the nanofiber obtained in Example 3 was 2.0%. Table 1 shows the evaluation results obtained using the obtained nanofibers. Polylactic acid that is easily thermally deteriorated compared to polyester, but as a result of suppressing the gelation rate to 2.0%, it is good except that it gives a step to Example 1 in terms of wear resistance, pilling properties, and wiping properties. It became the nanofiber which has a characteristic.

Example 4
In the sea-island type composite fiber for obtaining nanofibers, nanofibers were obtained in the same manner as in Example 1 except that the composite ratio was changed to sea / island = 60/40. Table 1 shows the evaluation results obtained using the obtained nanofibers. In Example 4, since the discharge amount of the island component polymer was reduced, the residence time in the spinning machine was slightly increased, and the gelation rate was increased. Therefore, in Example 1 in terms of wear resistance and pilling properties of the nanofiber, It was a step away, but the other items had good characteristics.

Example 5
In the production of sea-island composite fibers for obtaining nanofibers, a sea-island composite spinneret (number of islands × number of single yarns = 40960) having 2048 islands and 20 holes was used, and the composite ratio was sea / island = 40 / 60. Nanofibers were obtained in the same manner as in Example 1 except that the polymer discharge amount was changed so that the fineness configuration of the drawn yarn was 33 dtex-20 filament. Table 1 shows the evaluation results obtained using the obtained nanofibers. Since the average single fiber diameter of the nanofiber obtained in Example 5 was 210 nm, which was thinner than Example 1, it was one step away from Example 1 in terms of wear resistance and pilling properties. The item had good characteristics.

Example 6
In the production of sea-island type composite fibers for obtaining nanofibers, the example is except that the polymer discharge rate was changed so that the composite ratio was sea / island = 20/80 and the fineness configuration of the drawn yarn was 185 dtex-112 filaments Nanofibers were obtained by the same method as in 1. Table 1 shows the evaluation results obtained using the obtained nanofibers. Since the average single fiber diameter of the nanofibers obtained in Example 6 was 980 nm, which was thicker than Example 1, it was one step away from Example 1 in terms of scratch properties and wiping properties. Had good characteristics.

Example 7
Table 1 shows the evaluation results obtained using the same nanofiber as in Example 1 except that the gelation rate is 2.9%. Although the gelation rate of the nanofiber was high and it was a step over to Example 1 in terms of wear resistance and pilling properties, it had good scratch properties.

Comparative Example 1
In the production of sea-island type composite fibers for obtaining nanofibers, the examples are except that the polymer discharge rate was changed so that the composite ratio was sea / island = 20/80 and the fineness configuration of the drawn yarn was 205 dtex-112 filaments. Nanofibers were obtained by the same method as in 1. Table 1 shows the evaluation results obtained using the obtained nanofibers. Since the average single fiber diameter of the nanofiber obtained in Comparative Example 1 was 1,030 nm, which was larger than that of Example 1, it was inferior in terms of scratch properties and wiping properties.

Comparative Example 2
A sea-island composite spinneret with 70 islands and 9 holes (number of islands × number of sea-island single yarns = 630) was used, the composite ratio was sea / island = 20/80, and the fineness of the drawn yarn was 44 dtex-9 filaments. In the same manner as in Example 1 except that the polymer discharge amount was changed, ultrafine fibers were obtained. The evaluation results are shown in Table 1. Since the average single fiber diameter of the nanofiber obtained from Comparative Example 2 was 2,240 nm, which was larger than that of Example 1 and Comparative Example 1, the results were greatly inferior in terms of scratch properties and wiping properties. It was.

Comparative Example 3
Nanofibers were obtained in the same manner as in Example 1 except that chip powder washing before spinning was simplified and dry chips having a chip powder content of 2.4% were used. Table 1 shows the evaluation results obtained using the obtained nanofibers. The nanofiber obtained in Comparative Example 3 had a gelation rate of 3.1%, which was higher than that of Example 1, and was inferior in terms of wear resistance and pilling property.

Comparative Example 4
Nanofibers were obtained in the same manner as in Example 1 except that dry chips that were not washed with chip powder before spinning were used. Table 1 shows the evaluation results obtained using the obtained nanofibers. The nanofiber obtained in Comparative Example 4 had a gelation rate of 4.7%, which was higher than that of Example 1 and Comparative Example 3, and was inferior in terms of wear resistance and pilling properties. It was.

Claims (4)

  Nanofibers having an average single fiber diameter of 50 to 1000 nm and a gelling rate of 0.1 to 3.0% made of a thermoplastic resin.   The nanofiber according to claim 1, wherein the thermoplastic resin is polyester.   The nanofiber according to claim 1, wherein the thermoplastic resin is polyamide.   A woven or knitted fabric using the nanofiber according to any one of claims 1 to 3.