JP2016094687A - Thermoplastic resin fiber aggregate and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a thermoplastic resin fiber aggregate which can easily control a fiber diameter in a range from a submicron or less to a micron order; to provide a fiber aggregate which comprises thermoplastic resin fibers having a fiber diameter of a submicron or less and is free of shots (particulate resin); and to provide a method for producing the fiber aggregate.SOLUTION: A method for producing a thermoplastic resin fiber comprises: melt-kneading a thermoplastic resin by a melt-kneading extruder having a die attached to the front end thereof; feeding the molten resin into the die; discharging a strand from a resin discharge port of the die; drawing the strand by air at a temperature higher than a resin melting temperature from an air discharge port provided so as to be adjacent to the resin discharge port of the die, thereby obtaining a fiber which has been made fine; and collecting the obtained fiber on a collector. A distance between the resin discharge port and the air discharge port is in the rage of 2-20 [mm]. Thus, there is provided a method for producing a thermoplastic resin fiber aggregate. There is also provided a fiber aggregate which comprises thermoplastic resin fibers having an average fiber diameter in the range of 50 [nm]-1 [μm] and is free of shots.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fiber assembly made of an extremely fine thermoplastic resin (hereinafter referred to as a thermoplastic resin fiber assembly) and a method for producing the thermoplastic resin fiber assembly.

A melt blow method is known as a method for producing a fiber made of a thermoplastic resin (see References 1, 2, 3, etc.).
However, the melt blow method is a method in which the molten resin discharged from the resin discharge port at the tip of the nozzle is stretched by blowing high temperature air (Air) instantaneously and instantaneously after discharge, and the fiber diameter is reduced. When trying to obtain a fiber having a fiber diameter of less than a micron, that is, a nanoscale fiber diameter, it is necessary to increase the flow rate of high-temperature air. In this case, the nonwoven fabric made of fibers collected in the collector section is a point of intersection between the fibers. In addition to being fused, a large amount of particulate resin called a shot is contained, resulting in a problem that the quality deteriorates. For this reason, a product made of such a non-woven fabric causes shots to fall off during transportation and handling, or causes dirt, and when used as a resin filler, the surface is crumpled and the appearance is reduced. There were various problems such as factors.

JP 2004-348984 A JP 2002-105834 A JP 2004-348984 A

  The problem to be solved by the present invention is to provide a method for producing a thermoplastic resin fiber assembly in which the fiber diameter can be easily controlled from the sub-micron range to the micron order. It is another object of the present invention to provide a fiber assembly made of thermoplastic resin fibers having a fiber diameter of submicron or less and having no shot, and a method for easily manufacturing the assembly.

  As a result of diligent efforts to solve the above problems, the present inventors have solved the present invention by the following means.

That is, the present invention melt-kneads a thermoplastic resin with a melt-kneading extruder having a die attached to the tip, and sends the molten resin to the die,
A strand is discharged from the resin discharge port of the die, and a fine fiber is obtained by stretching the strand with air at a temperature higher than the resin melting temperature from an air discharge port installed adjacent to the resin discharge port of the die. A method for producing a thermoplastic resin fiber assembly, in which collected fibers are collected in a collector,
The present invention relates to a method for producing a thermoplastic resin fiber assembly in which a distance between a resin discharge port and an air discharge port is in a range of 2 to 20 [mm].

  Further, the present invention is an aggregate composed of thermoplastic resin fibers having an average fiber diameter in the range of 50 [nm] to 1 [μm], and the aggregate is a particle existing in a 100 μm square in an SEM image The present invention relates to a thermoplastic resin fiber assembly in which the number of glassy resins is 5 or less.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a thermoplastic resin fiber aggregate with easy control of a fiber diameter from the submicron range to the micron order range can be provided. In particular, it is possible to provide a fiber assembly made of thermoplastic resin fibers having a fiber diameter of submicron or less and having no shot, and a method for easily producing the fiber assembly.

It is a conceptual diagram of an example of the apparatus which can be used suitably for the manufacturing method of the thermoplastic resin fiber aggregate of this invention. 2 is a cross-sectional view of the die of FIG. It is a conceptual diagram of the melt blow apparatus used in Comparative Examples 3 and 4. It is sectional drawing of the die slit for meltblowing used in Comparative Examples 3 and 4. It is a SEM photograph of the PPS resin fiber aggregate obtained in Example 1 (magnification 1,000 times). It is a SEM photograph of the PPS resin fiber aggregate obtained in Example 1 (magnification 3000 times). It is a SEM photograph of the PPS resin fiber aggregate obtained in Comparative Example 4 (magnification 1,000 times).

The method for producing the thermoplastic resin fiber of the present invention comprises:
Melt and knead the thermoplastic resin with a melt kneading extruder with a die attached to the tip, and send the molten resin to the die.
A strand is discharged from the resin discharge port of the die, and a fine fiber is obtained by stretching the strand with air at a temperature higher than the resin melting temperature from an air discharge port installed adjacent to the resin discharge port of the die. A method for producing a thermoplastic resin fiber assembly in which collected fibers are collected in a collector, wherein the distance between the resin discharge port and the air discharge port is in the range of 2 to 20 [mm]. .

  Examples of the thermoplastic resin used in the present invention include polyolefins such as polypropylene, polyethylene, and polybutene, cyclic polyolefins, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon-6 and nylon 6,6, polystyrene, and syndiotactic polystyrene. , Polyurethane, polylactic acid, polyvinyl alcohol, polyarylene sulfide resins such as polyphenylene sulfide, polysulfone, liquid crystal polymer, ethylene vinyl acetate copolymer, polyacrylonitrile, polyoxymethylene, polyolefin-based thermoplastic elastomer, and combinations thereof Among these, polyarylene sulfide having excellent flame retardancy and dimensional stability is preferable.

(Polyarylene sulfide resin)
The polyarylene sulfide resin (PAS resin) preferably used in the present invention has a resin structure having a repeating unit of a structure in which an aromatic ring and a sulfur atom are bonded. )

(Wherein, R ¹ and R ² each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a nitro group, an amino group, a phenyl group, a methoxy group, or an ethoxy group). It is a resin having a structural site as a repeating unit.
Here, in the structural site represented by the formula (1), R ¹ and R ² in the formula are preferably hydrogen atoms from the viewpoint of the mechanical strength of the polyarylene sulfide resin. A compound bonded at the para position represented by the following formula (2) is preferable.

Among these, in particular, the bond of the sulfur atom to the aromatic ring in the repeating unit is a structure bonded at the para position represented by the structural formula (2). In terms of surface.

  Further, the polyarylene sulfide resin is not only the structural portion represented by the formula (1), but also the following structural formulas (3) to (6).

The structural site represented by the formula (1) may be included at 30 mol% or less of the total with the structural site represented by the formula (1). In particular, in the present invention, the structural portion represented by the above formulas (3) to (6) is preferably 10 mol% or less from the viewpoint of heat resistance and mechanical strength of the polyarylene sulfide resin. In the case where the polyarylene sulfide resin contains a structural portion represented by the above formulas (3) to (6), the bonding mode thereof may be either a random copolymer or a block copolymer. .
The polyarylene sulfide resin has the following formula (7) in its molecular structure.

May have a trifunctional structural site represented by the formula (1) or a naphthyl sulfide bond, but is preferably 3 mol% or less, particularly 1 mol%, based on the total number of moles with other structural sites. The following is preferable.

  The physical properties of the polyarylene sulfide resin are not particularly limited as long as the effects of the present invention are not impaired, but are as follows.

The polyarylene sulfide resin used in the present invention preferably has a melt viscosity (V6) measured at 300 ° C. in the range of 1 to 1000 [Pa · s], and further has a good balance between fluidity and mechanical strength. Therefore, the range of 1 to 100 [Pa · s] is more preferable, and the range of 5 to 50 [Pa · s] is particularly preferable. However, in the present invention, the melt viscosity (V6) is as follows: polyarylene sulfide resin using a flow tester manufactured by Shimadzu Corporation, CFT-500C, 300 ° C., load: 1.96 × 10 ⁶ Pa, L / D = 10/1 The melt viscosity is measured after holding for 6 minutes.

  The non-Newtonian index of the polyarylene sulfide resin used in the present invention is not particularly limited as long as the effects of the present invention are not impaired, but is preferably in the range of 0.90 to 2.00. When the linear polyarylene sulfide resin is used, the non-Newton index is preferably in the range of 0.90 to 1.50, and more preferably in the range of 0.95 to 1.20. Such a polyarylene sulfide resin is excellent in mechanical properties, fluidity, and abrasion resistance. However, the non-Newtonian index (N value) is measured by measuring the shear rate and shear stress using a capillograph at 300 ° C, the ratio of the orifice length (L) to the orifice diameter (D), and L / D = 40. These are values calculated using the following formula.

[Wherein SR represents a shear rate (second ⁻¹ ), SS represents a shear stress (dyne / cm ² ), and K represents a constant. The closer the N value is to 1, the closer the PPS is to a linear structure, and the higher the N value is, the more branched the structure is.

  The method for producing the polyarylene sulfide resin used in the present invention is not particularly limited. For example, 1) a dihalogenoaromatic compound and, if necessary, other copolymerization components are polymerized in the presence of sulfur and sodium carbonate. Method 2) A method of polymerizing a dihalogenoaromatic compound and, if necessary, another copolymer component in the presence of a sulfidizing agent in a polar solvent, 3) p-chlorothiophenol, and further necessary Examples of such a method include self-condensation with other copolymerization components, 4) a method of melt polymerization of a diiodo aromatic compound, elemental sulfur, and, if necessary, a polymerization inhibitor in the presence of a polymerization catalyst. Among these methods, the method 2) is versatile and preferable. In the reaction, an alkali metal salt of carboxylic acid or sulfonic acid or an alkali hydroxide may be added to adjust the degree of polymerization. Among the above methods 2), a hydrous sulfiding agent is introduced into a mixture containing a heated organic polar solvent and a dihalogeno aromatic compound at a rate at which water can be removed from the reaction mixture, and the dihalogeno aromatic compound and A method for producing a polyarylene sulfide resin by reacting with a sulfidizing agent and controlling the amount of water in the reaction system in the range of 0.02 to 0.5 mol relative to 1 mol of the organic polar solvent ( Japanese Patent Application Laid-Open No. 07-228699), a polyhaloaromatic compound, an alkali metal hydrosulfide and an organic acid alkali metal salt in the presence of a solid alkali metal sulfide and an aprotic polar organic solvent. 0.01-0.9 mol of organic acid alkali metal salt and 1 mol of water in the reaction system with respect to 1 mol of aprotic polar organic solvent A method of reacting while controlling the range of .02 mole (WO2010 / 058713 pamphlet reference.) Is what is particularly preferably obtained by.

  In the method for producing a thermoplastic resin fiber assembly of the present invention, first, the thermoplastic resin is further optionally added with additives such as an antioxidant, an antifoaming agent, a preservative, and a rust inhibitor. In the temperature range above the melting point of the thermoplastic resin, preferably in the temperature range above the melting point + 10 ° C., more preferably in the temperature range from the melting point + 10 ° C. to the melting point + 100 ° C., more preferably from the melting point + 20 ° C. to the melting point + 50 ° C. A melt is obtained by melt-kneading in a temperature range.

  The melt-kneading conditions are not particularly limited as long as the effects of the present invention are not impaired. For example, melt-kneading is performed under conditions where the discharge amount of the resin component is in the range of 0.6 to 30 (g / min). Is preferred.

  In addition, when an additive is added as an optional component to the thermoplastic resin, it is preliminarily mixed uniformly with a tumbler or a Henschel mixer in advance, and then charged into a melt-kneading extruder such as a twin-screw kneading extruder. It is preferable to do.

  The thermoplastic resin melted by the melt kneading extruder is discharged as a molten resin from a die having a resin discharge port.

  The cross-sectional shape of the fiber according to the present embodiment is not particularly limited, and is not limited to a normal circular cross section, but a triangular cross section, a quadrangular cross section, a Y-shaped cross section, a cross section, a C-shaped cross section, a hollow cross section, a rice field cross section, and the like. The cross-sectional shape of the discharge port can be selected as appropriate according to the cross-sectional shape.

  The inner diameter of the resin discharge port (nozzle hole inner diameter) is not particularly limited as long as the effects of the present invention are not impaired, but from the viewpoint of fiber miniaturization and discharge stability, a range of 0.3 to 1.0 mmφ is preferable. The range of 0.4-0 and 9 mmφ is more preferable.

  The die temperature is preferably in the same range as the temperature at which the resin is melt-kneaded in the melt-kneading extruder. Specifically, it is preferably +10 to 100 ° C. from the melting temperature of the resin, more preferably the melting point of the resin +10 to 50 ° C. If it is melting | fusing point +10 degreeC or more, since solidification of resin is prevented and sufficient extending | stretching advances, it is preferable. On the other hand, if it is melting | fusing point +50 degrees C or less, since gelatinization and oxidation of resin can be prevented, it is preferable.

  The amount of molten resin discharged from the resin discharge port is not particularly limited as long as the effects of the present invention are not impaired, but is preferably in the range of 0.5 to 30.0 g / min, and more preferably 0.7 to 20.0 g. / Min is more preferable. If it is 0.7 g / min or more, it is preferable because the stability of ejection can be secured.

  The discharge rate (V1) of the molten resin from the resin discharge port is not particularly limited as long as the effect of the present invention is not impaired, but is preferably in the range of 0.05 to 2.80 m / s, and more preferably 0.07 to More preferably, the range is 1.90 m / s.

  At the same time as the molten resin is discharged from the resin discharge port, the molten polymer discharged in a strand shape is stretched by air having a temperature higher than the die temperature discharged from the air discharge port provided adjacent to the resin discharge port. A fine fiber is obtained.

The shape and the diameter of the air discharge port are not particularly limited as long as the effects of the present invention are not impaired. For example, in the case of one hole, the diameter is preferably in the range of 1.0 to 5.0 mmφ. More preferably, it is in the range of 2.0 to 4.0 mmφ. From the viewpoint of airflow stabilization, 2.0 mmφ or more is preferable, and from the viewpoint of suppressing the decrease in air temperature and air speed, it is preferably 4.0 mmφ or less.
The shape of the air discharge port may be a slit type or a plurality of holes in addition to a single hole.

  The temperature of the air when discharged from the air discharge port is not particularly limited as long as the effects of the present invention are not impaired, but is preferably in the range of +10 to 100 ° C. higher than the resin melting temperature, and +10 higher than the resin melting temperature. More preferably, the temperature is in the range of -50 ° C higher. If the temperature range is higher than the resin melting temperature by 10 ° C or higher, solidification of the molten polymer can be prevented. On the other hand, if the temperature range is 50 ° C or higher than the resin melting temperature, the resin gelation or This is preferable because oxidation can be prevented.

  The speed at which air is discharged from the air discharge port (air discharge speed (V2)) is not particularly limited as long as the effect of the present invention is not impaired, but is preferably in the range of 300 to 1200 mm / s, and more preferably 500 to More preferably, it is in the range of 1000 mm / s. If it is 500 mm / s or more, it is preferable because the fiber becomes finer. On the other hand, if it is 1000 mm / s or less, it is preferable from the viewpoint of stabilizing the airflow formed by air.

  The air component uses air from the viewpoint of productivity, but is not particularly limited as long as the effects of the present invention are not impaired. From the viewpoint of blocking oxygen and preventing gelation and oxidation of the molten polymer, nitrogen air or the like is used. Inert air may be used.

The speed ratio (V2 / V1) of the air speed (V2) at the air discharge port to the strand speed (V1) discharged from the resin discharge port is not particularly limited as long as the effect of the present invention is not impaired. From the viewpoint of easily producing fibers having a fiber diameter of a micron unit, it is preferably in the range of 1 × 10 ^{2 to} 150 × 10 ² , and more preferably in the range of 4 × 10 ^{2 to} 120 × 10 ^2. More preferred.

  The strand discharge direction at the resin discharge port and the air discharge direction at the air discharge port are substantially parallel. Thus, in order to make the discharge direction of the strand at the resin discharge port and the discharge direction of the air at the air discharge port substantially parallel, the center line of the discharge direction of the nozzle provided on the die and the air discharge hole The center lines in the discharge direction are preferably designed and manufactured so as to be substantially parallel to each other. Note that “substantially parallel” refers to the angle formed by the strand discharge direction (center line of the nozzle discharge direction) at the resin discharge port and the air discharge direction (center line of the air discharge hole discharge direction) at the air discharge port. Although it is preferably 0 °, it means that it may be within a range of −5 ° to + 5 °.

  The distance between the air discharge port 5 and the resin discharge port is in the range of 2 to 20 mm, preferably in the range of 5 to 10 mm.

The obtained thermoplastic resin fibers are collected in the collector part and obtained as a fiber assembly.
The distance between the resin discharge port and the collector portion is not particularly limited as long as the effects of the present invention are not impaired, but is preferably in the range of 30 to 300 cm, and more preferably in the range of 100 to 200 cm. If it is 100 cm or more, it becomes possible to maintain the high temperature state of the molten resin, and it is preferable for reducing the diameter because it takes a long time to receive the stretching effect by air. It is preferable because fiber collection is easy.

  The collector is not particularly limited as long as the effects of the present invention are not impaired. However, it is preferable that the collector is an apparatus that can continuously collect with a roll.

  An example of an apparatus used in the present invention will be described with a schematic view. In FIG. 1, an apparatus used in the present invention includes a melt-kneading extruder 1, a hopper 2 for supplying a thermoplastic resin to the extruder 1, a die 3 provided at the tip of the extruder 1, A nozzle 4 serving as a resin discharge port 4a attached to the tip, an air discharge port 5 provided adjacent to the nozzle, and a collector roller 6 provided at a predetermined distance from the resin discharge port 4a. Air heated by a heater 9 is supplied to the die 3 from an air supply device 8 through an air transport pipe 7.

  A sectional view of the die 3 in FIG. 1 is shown in FIG. The die 3 includes an upper die plate 3a and a lower die plate 3b having a heater 10 therein. By combining the upper die plate 3a and the lower die plate 3b, an air chamber 11 for storing heated air is formed inside the die 3. In addition, the air transport pipe 7 is connected to the air chamber 11, and heated air is supplied. On the other hand, the molten polymer melted by the extruder 1 is accumulated in the resin chamber 13 through the inlet 12 and heated so as to maintain the molten state by the heater 10, and then passes through the nozzle 4 and passes through the resin discharge port 4 a to the strand. It is discharged in a shape.

The center line ψ4a in the discharge direction of the nozzle 4 and the center line ψ5 in the discharge direction of the air discharge hole 5 are designed to be substantially parallel to each other. Therefore, the discharge direction of the strand discharged from the resin discharge port 4a and the air discharge The discharge direction of air at the outlet is substantially parallel.
Further, the thermoplastic resin fibers collected by the collector roller 6 are accumulated on the collection surface 14.

  In the production method of the present invention, since the fiber diameter can be easily controlled from the submicron range to the micron order, the fiber diameter (diameter) of the obtained fiber is not particularly limited, but is preferably 50 μm. It is the following range, More preferably, it is the range of 10 micrometers or less, More preferably, it is the range of 1 micrometer or less, Most preferably, it is the range of 800 nm or less. The lower limit of the fiber diameter is not particularly limited, but is preferably in the range of 50 nm or more, more preferably in the range of 100 nm or more.

The fiber diameter is a fiber diameter measured by a scanning electron microscope. Specifically, for example, SEM is measured using an S-2380N type manufactured by Hitachi, Ltd.
In the thermoplastic resin fiber of the present invention, the aspect ratio represented by the fiber length / fiber diameter is preferably 2 or more, more preferably 10 or more, further preferably 100 or more, and 1000 or more. Most preferably.

  Further, the thermoplastic resin fiber aggregate obtained by the production method of the present invention is an aggregate formed by entangled fibers having a linear structure in which fibers are not fused to each other. Is forming. Furthermore, by the production method of the present invention, a high-quality fiber assembly that suppresses the generation of particulate resin called a shot while having a fiber diameter of sub-micron or smaller, that is, a nanoscale fiber diameter is obtained. You can also.

  Since the thermoplastic resin fiber assembly of the present invention also has various performances such as heat resistance and dimensional stability inherent to the thermoplastic resin, for example, electrical / Used as a fiber used in the fields of automotive parts such as electronic parts, lamp reflectors and various electrical parts, interior materials for various buildings, aircraft and automobiles, precision parts such as OA equipment parts, camera parts and watch parts can do. More specifically, it can be suitably used for a separator used for a lithium ion battery or the like, or a filter used for a bag filter or the like. When used in these applications, the fiber assembly according to the present embodiment may be used alone, or may be used in appropriate combination with other fibers.

  The present invention will be specifically described below with reference to examples. These examples are illustrative and not limiting.

Example 1
Using the apparatus described in FIGS. 1 and 2, polyphenylene sulfide resin DIC. PPS (V6 melt viscosity at 300 ° C., 10 Pa · s, non-NT index 1.1) is melt-kneaded with an extruder (temperature 320 ° C.), then sent to a die (resin chamber set temperature 320 ° C.), and then provided to the die The molten resin is discharged in a strand shape from a resin discharge port at the tip of a 0.41 mm diameter nozzle at a resin discharge rate of 1.5 g / min and a resin discharge speed (V1) of 0.14 m / sec. Air was discharged from the air discharge port at an air temperature of 360 ° C., an air flow rate of 75 liters / min, and an air flow rate (V2) of 830 m / sec, and the molten resin discharged in a strand shape was stretched. The speed ratio (V2 / V1) between the discharge speed V1 at the resin discharge port of molten resin and the air discharge speed V2 at the air discharge port (V2 / V1) is 59 × 10 ² , resin discharge port-air discharge port 5 mm, resin discharge port-collector interval The molten resin is stretched with air under the condition that the angle formed by the center line (ψ4a) of the discharge direction of the nozzle 4 and the center line (ψ5) of the discharge direction of the air discharge hole 5 is 0 degrees (substantially parallel). A fiber assembly (1) composed of the fibers (1) was obtained. The fibers constituting the obtained fiber assembly had an average fiber diameter of 0.5 μm and a long fiber shape, and no particulate matter was confirmed in the fiber assembly. The evaluation results are shown in Table 1.

Example 2
The resin discharge rate is 0.9 g / min, the resin discharge speed (V1) is 0.08 m / sec, the air flow rate is 120 liters / min, the air flow rate (V2) is 950 m / sec, and the ratio between the resin discharge speed V1 and the air discharge speed V2 ( Except that V2 / V1) was 112 × 10 ² , the molten resin was stretched with air in the same manner as in Example 1 to obtain a fiber assembly (2) composed of PPS fibers (2). The evaluation results are shown in Table 1.

Example 3
The resin discharge rate is 8.0 g / min, the resin discharge rate (V1) is 0.75 m / sec, the air flow rate is 45 liters / min, the air flow rate (V2) is 350 m / sec, and the ratio of the resin discharge rate V1 and the air discharge rate V2 ( Except that V2 / V1) was 4.6 × 10 ² , the molten resin was stretched with air in the same manner as in Example 1 to obtain a fiber assembly (3) composed of PPS fibers (3). The evaluation results are shown in Table 1.

Example 4
Except that the interval between the resin discharge port and the air discharge port was 3 mm, the molten resin was stretched with air in the same manner as in Example 1 to obtain a fiber assembly (4) composed of PPS fibers (4). The evaluation results are shown in Table 1.

Example 5
Except that the interval between the resin discharge port and the air discharge port was 20 mm, the molten resin was stretched with air in the same manner as in Example 1 to obtain a fiber assembly (5) composed of PPS fibers (5). The evaluation results are shown in Table 1.

Example 6
Resin discharge rate 0.6 g / min, resin discharge speed (V1) 0.06 m / sec, air flow rate 80 liter / min, air discharge speed (V2) 850 m / sec, ratio of resin discharge speed V1 and air discharge speed V2 Except that (V2 / V1) was 150 × 10 ² , the molten resin was stretched with air in the same manner as in Example 1 to obtain a fiber assembly (6) composed of PPS fibers (6). The evaluation results are shown in Table 2.

Example 7
The resin discharge rate is 38.2 g / min, the resin discharge speed (V1) is 3.6 m / sec, the air flow rate is 45 l / min, the air discharge speed (V2) is 360 m / sec, and the ratio of the resin discharge speed V1 and the air discharge speed V2 Except that (V2 / V1) was set to 1.0 × 10 ² , the molten resin was stretched with air in the same manner as in Comparative Example 1 to obtain a fiber assembly (7) composed of PPS fibers (7). The evaluation results are shown in Table 2.

Comparative Example 1
The molten resin was stretched with air in the same manner as in Example 1 except that the interval between the resin discharge port and the air discharge port was 1 mm. However, fiberization was not suitable and a fiber assembly was not obtained. The evaluation results are shown in Table 2.

Comparative Example 2
The molten resin was stretched with air in the same manner as in Example 1 except that the interval between the resin discharge port and the air discharge port was 25 mm. However, fiberization was not suitable and a fiber assembly was not obtained. The evaluation results are shown in Table 2.

Comparative Example 3
Using the general-purpose melt-blowing device shown in FIG. 3, the air discharge slit (resin discharge port-air) having a length of 3 inches shown in FIG. 4, a lip width of the resin discharge slit of 0.60 mm, and a width of 0.25 mm on both sides thereof. A fiber assembly was produced using a melt blow die slit having a discharge port interval of 1 mm or less. That is, polyphenylene sulfide resin DIC. PPS (V6 melt viscosity at 300 ° C., 10 Pa · s, non-NT index 1.1) is melt-kneaded with an extruder (temperature 320 ° C.) and then fed into a melt blow die slit, where the air temperature is 360 ° C. and the resin discharge amount is 1. 5 g / min, resin discharge speed (V1) 0.15 m / sec, air flow rate 1.2 Nm ³ / min (10 divisions), air discharge speed (V2) 787 m / sec, resin discharge speed V1 and air discharge speed V2 The ratio (V2 / V1) is 53 × 10 ² , the resin discharge port-collector interval is 20 cm, and the angle formed by the center line (ψ110) in the discharge direction of the resin discharge slit and the center line (ψ111) in the discharge direction of the air discharge slit is Melt blow molding was performed under the condition of 45 degrees to obtain a melt blown nonwoven fabric. The fibers constituting the obtained non-woven fabric had an average fiber diameter of 5.0 μm, retained a mixed form of short fibers and long fibers, and a large number of particulate substances were confirmed in the fiber assembly. The evaluation results are shown in Table 2.

Comparative Example 4
The resin discharge rate is 1.0 g / min, the resin discharge speed (V1) is 0.10 m / sec, the air flow rate is 1.6 Nm ³ / min (10 divisions), the air discharge speed (V2) is 1050 m / sec, and the resin discharge speed V1 Except that the ratio (V2 / V1) of the air discharge speed V2 was 106 × 10 ² , the melted resin was melt blow molded in the same manner as in Comparative Example 3, but fiberization was not suitable and a fiber assembly was not obtained. . The evaluation results are shown in Table 2.

* 1 ... Measurement is not possible without fiberization

However, each measured value in the above Examples and Comparative Examples was measured by the following method.

Evaluation Method A platinum-palladium alloy was vapor-deposited on polyphenylene sulfide fiber, observed with a scanning electron microscope (SEM Hitachi, Ltd., S-2380N type), and evaluated as follows.

(Fiber diameter)
As for the fiber diameter, any 20 non-overlapping spots are selected at a magnification (1000 times) at which the fiber diameter can be confirmed, and further, any 5 fibers are extracted at the 20 places, and a predetermined magnification ( The fiber diameter was confirmed at 3000 times. The number average of the obtained fiber diameters of the above 100 points (20 points × 5 points) was calculated and used as the fiber diameter of the sample.

(Observation and evaluation of particulate resin)
Prepare 5 points as a test piece by cutting a non-woven fabric with a basis weight of 100 g / m ² into a size of 1 cm × 1 cm, and extract 20 particles at a predetermined magnification (1000 times) for each test piece. The state of the glassy resin was observed.
The test piece was observed at 5 points × 20 places, the number of particulate resins present in a 100 μm square was calculated as the number average, and classified into the following evaluations.
"No shot" ... When there is less than one particulate resin ("◎" in the table)
“Small shots” ・ ・ ・ In case of 1 or more and less than 5 (“○” mark in the table)
“There are not a few shots” ・ ・ ・ When there are 5 or more and less than 50 (“△” mark in the table)
“Many shots” ・ ・ ・ When there are 50 or more shots

1 Melting and kneading extruder
2 Hopper
3 die
3a Upper die plate
3b Lower die plate
4a Resin outlet
4 nozzles
5 Air outlet
6 Collector roller
7 Air transport pipe
8 Air supply device
9 Heater
10 Heater
11 Air chamber
12 Introduction port 13 Resin chamber 14 Fiber collection surface ψ4a Center line in the discharge direction of the nozzle 4
ψ5 Center line 21 in the discharge direction of the air discharge hole 5 Melt blow die (high temperature air discharge nozzle part)
22 Melt blow die (molten resin discharge nozzle)
101 Melt kneading extruder
102 hopper
123 Die slit
110 Resin outlet (resin outlet slit)
111 Air discharge port (Air discharge slit)
106 Collector roller
107 Pneumatic transport pipe
108 Air supply device
109 heater
112 Introduction port 114 Fiber collection surface ψ110 Center line in the discharge direction of the resin discharge slit
ψ111 Center line in the discharge direction of the air discharge slit

Claims (6)

Melt and knead the thermoplastic resin with a melt kneading extruder with a die attached to the tip, and send the molten resin to the die.
A strand is discharged from the resin discharge port of the die, and a fine fiber is obtained by stretching the strand with air at a temperature higher than the resin melting temperature from an air discharge port installed adjacent to the resin discharge port of the die. A method for producing a thermoplastic resin fiber assembly, in which collected fibers are collected in a collector,
A method for producing a thermoplastic resin fiber assembly, wherein a distance between a resin discharge port and an air discharge port is in a range of 2 to 20 [mm]. The speed ratio (V2 / V1) of the air speed (V2) at the air discharge port to the speed (V1) of the strand discharged from the resin discharge port is in the range of 1 × 10 ^{2 to} 150 × 10 ^2. Method for producing a thermoplastic resin fiber assembly. The method for producing a thermoplastic resin fiber assembly according to claim 1 or 2, wherein the strand discharge direction at the resin discharge port and the air discharge direction at the air discharge port are substantially parallel.   The method for producing a thermoplastic resin fiber assembly according to any one of claims 1 to 3, wherein a distance between the resin discharge port and the collector is in a range of 30 to 300 [cm].   The method for producing a thermoplastic resin fiber assembly according to any one of claims 1 to 4, wherein an average fiber diameter of the thermoplastic resin fibers is in a range of 50 [nm] to 50 [[mu] m]. A fiber assembly composed of thermoplastic resin fibers having an average fiber diameter in the range of 50 [nm] to 1 [μm],
The fiber aggregate is a thermoplastic resin fiber aggregate characterized in that, in an SEM image, the number of particulate resins present in a 100 μm square is 5 or less.