CN106661773B

CN106661773B - High-melting-point resin fiber and nonwoven fabric

Info

Publication number: CN106661773B
Application number: CN201580043328.4A
Authority: CN
Inventors: 郑贵宽; 横山绫
Original assignee: Daicel Corp
Current assignee: Daicel Corp
Priority date: 2014-10-20
Filing date: 2015-08-26
Publication date: 2020-05-22
Anticipated expiration: 2035-08-26
Also published as: JP6496120B2; KR20170074857A; KR102401754B1; WO2016063619A1; JP2016079536A; DE112015004760T5; CN106661773A; US20170298535A1

Abstract

The purpose of the present invention is to provide a high-melting-point resin fiber having a diameter of 4 [ mu ] m or less, which has excellent heat resistance, solvent resistance and processability, and a nonwoven fabric comprising the high-melting-point resin fiber. Another object of the present invention is to provide a method for efficiently producing a high-melting-point resin fiber having a diameter of 4 μm or less by using a laser melt electrospinning method. The high-melting-point resin fiber of the present invention is formed of a resin having a melting point of 250 ℃ or higher and has a diameter of 4 μm or less. The resin having a melting point of 250 ℃ or higher in the high-melting resin fiber of the present invention is preferably PEEK, and the crystallinity is preferably 30% or less.

Description

High-melting-point resin fiber and nonwoven fabric

Technical Field

The present invention relates to a high-melting-point resin fiber and a nonwoven fabric using a melt-type electrospinning method.

More specifically, the present invention relates to a high-melting resin fiber obtained by processing a high-melting resin (film) into an ultrafine fiber having a diameter of 4 μm or less by a melt-type electrospinning method (laser melt electrospinning method) using a laser beam as a heating means, and a nonwoven fabric formed of the high-melting resin fiber. The present application claims priority of Japanese patent application No. 2014-213828, filed in Japan at 10/20/2014, the contents of which are incorporated herein by reference.

Background

In recent years, fibers having a fiber diameter of submicron or nanometer order have attracted attention from the viewpoint of developing a novel material that effectively utilizes a large specific surface area and a fiber morphology. As a method for producing such fibers, for example, an electrospinning method (melt-type electrospinning method) in which a high voltage is caused to act on a polymer melt to form fibers has been proposed.

As a melt-type electrospinning method, for example, patent document 1 proposes a melt-type electrospinning method (laser melt electrospinning method) in which a thermoplastic resin is heated and melted by irradiation with laser light, and an electrospinning step in which a voltage is applied to a melted portion of the thermoplastic resin to collect elongated fibers in a collector is performed to produce fibers. In this method, a thread-like resin is used as a spinning material, and the fiber is ejected from the tip thereof to produce a fiber.

In patent document 2, in the above laser melt electrospinning method, a sheet-like object made of a thermoplastic resin is irradiated with a linear laser beam to heat and melt an end portion of the sheet-like object in a linear shape, and a potential difference is provided between the melted portion and a metal collector, whereby a needle-like projection is formed in the heated and melted portion of the sheet-like object, and a fiber ejected from the needle-like projection is caused to fly in a direction of the metal collector to be collected by the metal collector or a collecting member interposed between the melted portion and the metal collector.

High melting point resins such as polyether ether ketone (PEEK), polyphenylene sulfide (PPS), and polyamide imide (PAI) are also called super engineering plastics having heat resistance, flame retardancy, chemical resistance, and impact resistance, and are widely used in applications in the fields of automobiles and electric/electronic devices. Among them, PEEK has a melting point of 334 ℃, has super heat resistance that can be continuously used at 250 ℃, and is an aromatic plastic having the highest heat resistance and chemical resistance to organic solvents and the like as a thermoplastic resin.

As a method for forming fibers (fibers) from these high-melting point resins, a method such as melt blowing is known, but since the diameter of the fibers is several μm to several tens μm, it is difficult to obtain further ultrafine nanofibers. Further, as a method for obtaining further ultrafine nanofibers, a method such as electrospinning is known, but it is often not used as a super engineering plastic having a high melting point such as PEEK because it is insoluble in an organic solvent or the like.

Documents of the prior art

Patent document

Patent document 1 Japanese laid-open patent publication No. 2007-239114

Patent document 2 Japanese patent laid-open publication No. 2010-275661

Disclosure of Invention

Technical problem to be solved by the invention

On the other hand, in the laser melt electrospinning method of patent document 2, the crystallinity of the raw material film cannot be controlled, and when the crystallinity is high, it is difficult to increase the processing speed. The diameter of the obtained fiber is 5 μm or more. Moreover, the obtained fiber has high crystallinity and is difficult to be processed and molded.

Accordingly, an object of the present invention is to provide a high-melting resin fiber having a diameter of 4 μm or less, which has heat resistance, solvent resistance and excellent processability, and a nonwoven fabric comprising the high-melting resin fiber. Another object of the present invention is to provide a method for efficiently producing a high-melting-point resin fiber having a diameter of 4 μm or less by using a laser melt electrospinning method.

Means for solving the problems

The present inventors have therefore made intensive studies to achieve the above object, and as a result, have found that a high-melting resin fiber having a diameter of 4 μm or less, which is made of a resin having a melting point of 250 ℃ or higher, can be obtained by using a laser melt electrospinning method and using a resin having a melting point of 250 ℃ or higher as a polymer sheet of a raw material, and have completed the present invention.

That is, the high-melting resin fiber of the present invention is formed of resin pores having a melting point of 250 ℃ or higher, and has a diameter of 4 μm or less.

In the high-melting-point resin fiber of the present invention, the resin having a melting point of 250 ℃ or higher is preferably PEEK.

The high-melting resin fiber of the present invention preferably has a crystallinity of 30% or less.

The method for producing high-melting-point resin fibers of the present invention is characterized in that a polymer sheet made of an amorphous high-melting-point resin is irradiated with a band-shaped laser beam to heat and melt an end portion of the polymer sheet in a linear shape, and a potential difference is provided between the melted band-shaped melted portion and a fiber collecting plate, whereby a needle-shaped protrusion is formed in the band-shaped melted portion of the polymer sheet, and fibers ejected from the needle-shaped protrusion are caused to fly in the direction of the fiber collecting plate and collected on the fiber collecting plate or a collecting member interposed between the melted portion and the fiber collecting plate, whereby high-melting-point resin fibers are obtained.

In the method for producing a high-melting-point resin fiber of the present invention, the conveying speed of the polymer sheet is preferably 2 to 20 mm/min.

In the method for producing a high-melting-point resin fiber of the present invention, the potential difference is preferably 0.1 to 30 kV/cm.

In the method for producing a high-melting-point resin fiber of the present invention, the polymer sheet has a viscosity of 800Pa · s or less as measured at 400 ℃ at a shear rate (shear rate) of 121.6 (1/s).

The nonwoven fabric of the present invention is characterized by being obtained from the high-melting-point resin fiber of the present invention.

That is, the present invention relates to the following inventions.

[1] A high-melting-point resin fiber having a diameter of 4 μm or less and formed of a resin having a melting point of 250 ℃ or higher.

[2] The high-melting-point resin fiber according to the above [1], wherein the resin having a melting point of 250 ℃ or higher is PEEK.

[3] The high-melting resin fiber according to the above [1] or [2], wherein the degree of crystallinity is 30% or less.

[4] The high-melting resin fiber according to any one of the above [1] to [3], wherein an average fiber diameter of the aggregate is 4 μm or less.

[5] A method for producing a high-melting-point resin fiber according to any one of [1] to [4], comprising:

a polymer sheet made of an amorphous high-melting-point resin is irradiated with a band-shaped laser beam to heat and melt an end of the polymer sheet in a linear shape, and a potential difference is provided between a melted band-shaped melted portion and a fiber collecting plate, whereby a needle-shaped protrusion is formed in the band-shaped melted portion of the polymer sheet, and fibers discharged from the needle-shaped protrusion are caused to fly in the direction of the fiber collecting plate and collected by the fiber collecting plate or a collecting member interposed between the melted portion and the fiber collecting plate, whereby high-melting-point resin fibers are obtained.

[6] The method for producing a high-melting-point resin fiber according to item [5], wherein the polymer sheet is conveyed at a speed of 2 to 20 mm/min.

[7] The process for producing a high-melting-point resin fiber according to the above [5] or [6], wherein the potential difference is 0.1 to 30 kV/cm.

[8] The method for producing a high-melting-point resin fiber according to any one of the above [5] to [7], wherein the polymer sheet has a viscosity of 800Pa · s or less as measured at 400 ℃ at a shear rate (shear rate) of 121.6 (1/s).

[9] The method for producing a high-melting-point resin fiber according to any one of the above [5] to [8], wherein the output power of the ribbon-shaped laser beam is 5 to 100W/13 cm.

[10] The method for producing a high-melting-point resin fiber according to any one of the above [5] to [9], wherein the polymer sheet has a crystallinity of 25% or less.

[11] A nonwoven fabric obtained from the high-melting-point resin fiber according to any one of [1] to [4 ].

ADVANTAGEOUS EFFECTS OF INVENTION

The high-melting resin fiber of the present invention has excellent processability due to low crystallinity, and also has excellent heat resistance and chemical resistance due to the use of a high-melting resin such as PEEK as a material. The nonwoven fabric using the high-melting resin fiber is formed of an extremely fine fiber, and is excellent in separation ability when used as a separator of a battery, a filter of a medical material, or the like, and also excellent in durability, heat resistance, and chemical resistance because a high-melting resin such as PEEK is used as a material.

Drawings

Fig. 1 is a schematic view schematically showing an example of the method for producing a high-melting-point resin fiber of the present invention.

Fig. 2 is a schematic view of a taylor cone formed in a ribbon fusion zone.

Fig. 3 is a cross-sectional view schematically showing an example of a nonwoven fabric production apparatus including the method for producing high-melting-point resin fibers of the present invention.

Description of the marks

1 laser generating source

2 beam expander and homogenizer

3 collimating lens

4 cylindrical lens group

5 ribbon laser light

6 high molecular sheet

6a band-shaped fusion zone

6b needle-like projection

7 holding member

8 fiber collecting plate

9 thermal imaging system

10 high voltage generating device

11 laser generating source

12 light path adjusting member

13 high-molecular sheet conveying device

14 fiber collecting plate

15 heating device

16 holding member

17 electrode

18 heat absorbing plate

19 laser light absorption plate

20a high voltage generating device

20b high voltage generating device

21 pulley

22 trapping member

23 case body

Detailed Description

[ high melting resin fiber ]

The high-melting resin fiber of the present invention is an ultrafine fiber having a small fiber diameter of 4 μm or less. The diameter of the fibers is preferably 3 μm or less (0.1 to 3 μm), more preferably 2 μm or less. The ultrafine fibers having such a diameter may include fibers having a fiber diameter of about 50 to 1000nm, for example. The diameter of the fiber can be adjusted by appropriately adjusting various conditions (for example, the thickness of the polymer sheet, the conveying speed of the polymer sheet, the laser intensity, and the like) in the method for producing the high-melting-point resin fiber described later. The diameter of the high-melting resin fiber can be measured, for example, by an electron microscope.

The high-melting-point resin fiber of the present invention is formed of a resin having a melting point of 250 ℃ or higher. The melting point of the high-melting resin fibers is preferably 260 ℃ or higher, more preferably 270 ℃ or higher, and still more preferably 280 ℃ or higher. The resin having a melting point of 250 ℃ or higher is not particularly limited, and examples thereof include: polyether ether ketone (PEEK) (melting point 334 ℃ C.), polyphenylene sulfide (PPS) (melting point 290 ℃ C.), polyamide imide (PAI) (melting point 300 ℃ C.), Polytetrafluoroethylene (PTFE) (melting point 327 ℃ C.), silicone resin (melting point about 300 ℃ C.), fluororesin (melting point 327 ℃ C.), liquid crystal polymer (melting point 260-300 ℃ C.), and the like. Among them, PEEK is preferable in terms of high melting point and excellent heat resistance and solvent resistance.

The high-melting resin fiber of the present invention preferably has a crystallinity of 30% or less. The crystallinity is more preferably 29% or less, and still more preferably 28% or less. When the crystallinity is 30% or less, the processability is excellent, and a nonwoven fabric, a filter, a separator, or the like can be easily formed. The crystallinity can be determined by, for example, X-ray diffraction method, DSC (differential scanning calorimeter) measurement, density method, or the like. In the present application, the crystallinity is calculated from the heat quantity obtained by DSC measurement by the method described in examples.

The high-melting-point resin fiber of the present invention is preferably obtained by a method for producing a high-melting-point resin fiber, which will be described later, using an amorphous high-melting-point resin as a raw material in the form of a polymer sheet.

The thickness of the amorphous high-melting-point resin (sheet) as the polymer sheet is, for example, 0.01 to 10mm, preferably 0.05 to 5.0 mm. When the thickness is within the above range, the high-melting resin fiber described later can be easily produced.

The average fiber diameter of the aggregate of the high-melting resin fibers of the present invention is not particularly limited, but is preferably 4 μm or less (0.1 to 4 μm), more preferably 3 μm or less, and still more preferably 2 μm or less. The average fiber diameter can be determined, for example, by the following method: the form of a plurality of (for example, 10) fibers is photographed by using a scanning electron microscope, and the diameters of about 10 fibers in any 1 image among the photographed plurality of images are measured by image processing software or the like, and averaged.

[ method for producing high-melting resin fiber ]

The high-melting resin fiber of the present invention is preferably produced by a laser melt electrospinning method described below. The laser melt electrospinning method is specifically the following method.

A method for producing a high-melting-point resin fiber (laser melt electrospinning) according to the present invention will be described with reference to the drawings. Fig. 1 is a schematic view schematically showing an example of a method for producing a high-melting-point resin fiber. In a method for producing high-melting-point resin fibers, a polymer sheet made of a high-melting-point resin (sheet) is irradiated with a ribbon-shaped laser beam to heat and melt an end of the polymer sheet linearly, and a potential difference is provided between the melted ribbon-shaped melted portion and a fiber collecting plate, whereby a needle-shaped protrusion is formed in the ribbon-shaped melted portion of the polymer sheet, and fibers discharged from the needle-shaped protrusion are caused to fly toward the fiber collecting plate and collected on the fiber collecting plate or a collecting member interposed between the melted portion and the fiber collecting plate, thereby obtaining fibers.

In the method for producing a high-melting-point resin fiber, as shown in fig. 1, laser light having a spot-like cross section emitted from a laser light source 1 is converted into a band-like laser light 5 having a linear cross section by an optical path adjusting device formed by a beam expander and homogenizer 2, a collimator lens 3, and a cylindrical lens group 4, and then a band-like fusion portion 6a of a polymer sheet 6 held by a holding member 7 is irradiated with the laser light, and a voltage is applied by a high voltage generating device 10, so that a potential difference is generated between the band-like fusion portion 6a and a fiber collecting plate 8 disposed below the polymer sheet 6. Further, the temperature of the belt-like fusion zone 6a can be observed by the thermal imaging camera 9, and conditions such as voltage and laser light to be irradiated can be optimized.

In the example shown in fig. 1, the holding member 7 holding the polymer sheet 6 also functions as an electrode, and when a voltage is applied to the holding member 7 by the high voltage generator 10, an electric charge is applied to the band-shaped melting portion 6a of the polymer sheet 6. The surface resistance value of the fiber collecting plate 8 is the same as that of metal. Examples of the shape include a plate shape, a roll shape, a belt shape, a mesh shape, a saw shape, a wave shape, a needle shape, and a thread shape. The optical path adjusting device is an assembly of optical components, and is formed by a beam expander and homogenizer 2, a collimator lens 3, a cylindrical lens 4, and the like. By using these optical path adjusting devices, the spot laser light can be converted into the ribbon laser light 5.

In the example shown in fig. 1, the band-shaped melting portion 6a of the polymer sheet 6 is heated and melted by irradiation of the band-shaped laser beam 5, and an electric charge is applied to the heated and melted portion. As shown in fig. 2, the surface of the charged ribbon-shaped fused part 6a is repelled by the charge accumulation, and a plurality of needle-shaped protrusions (taylor cones) 6b are formed gradually, and when the repulsive force of the charges exceeds the surface tension, the molten thermoplastic resin is ejected as fibers from the tip of the taylor cone toward the fiber collecting plate 8 by the electrostatic attraction, that is, the fibers are formed by the needle-shaped protrusions 6b and fly toward the fiber collecting plate 8. As a result, the elongated fibers are captured by the fiber capture plate 8. When the collection member is placed on the fiber collection plate 8, the fibers are collected by the collection member. That is, in the method for producing high-melting-point resin fibers of the present invention, the fiber collecting plate itself may be used as the member for collecting fibers, or the collecting member together with the fiber collecting plate may be placed on the fiber collecting plate. Fig. 2 is a schematic view of a taylor cone formed on the ribbon fusion section 6 a.

The number of taylor cones (the interval between taylor cones) shown in fig. 2 can be adjusted by appropriately changing the thickness of the polymer sheet 6. The increase in the taylor cone means that the height (h in fig. 2) of the taylor cone is increased.

The number of taylor cones is not particularly limited, but is preferably 1 or more per 2cm, more preferably 1 to 100/2 cm, in the portion of the polymer sheet after heating and melting. The reason is that: when the average diameter is 1 piece/2 cm or less, it is not preferable and is much preferable in view of the uniformity of the nonwoven fabric and the production amount, but when the average diameter is 100 pieces/2 cm or more, the uniformity is lowered by electric repulsion between taylor cones. More preferably 1 to 50/2 cm, and particularly preferably 2 to 10/2 cm.

Examples of the laser light generation source include: YAG laser and carbon dioxide (CO)₂) Laser, argon laser, excimer laser, helium-cadmium laser, and the like. Among them, a carbon dioxide laser is preferable in terms of high power efficiency and high meltability of the PEEK resin. The wavelength of the laser light is, for example, 200nm to 20 μm, preferably 500nm to 18 μm, and more preferably about 5 to 15 μm.

In the method for producing a high-melting-point resin fiber, when a band-shaped laser beam is irradiated, the thickness of the laser beam is preferably about 0.5 to 10 mm. When the thickness of the laser beam is less than 0.5mm, the formation of a taylor cone may become difficult, and when it exceeds 10mm, the melting residence time may become long, resulting in the deterioration of the material.

In addition, the output of the laser may be controlled within a temperature range in which the temperature of the ribbon-shaped melting portion is not less than the melting point of the thermoplastic resin and not more than the ignition point of the polymer sheet. The specific output power of the laser beam can be suitably selected depending on the physical properties (melting point, LOI value (limiting oxygen index)) and shape of the thermoplastic resin to be used, the transport speed of the polymer sheet, and the like, and is usually about 5 to 100W/13cm, preferably 20 to 60W/13cm, and more preferably 30 to 50W/13 cm. The intensity of the laser light is the output power of the spot beam emitted from the laser light source.

The temperature of the band-shaped melting portion is not particularly limited as long as it is a temperature not lower than the melting point of the high-melting resin and not higher than the ignition point, and is usually about 300 to 600 ℃, preferably 350 to 500 ℃.

In the method for producing a high-melting-point resin fiber of the present invention shown in fig. 1, the laser light is irradiated only from one direction to the band-shaped fused portion (end portion) of the polymer sheet, but the laser light may be irradiated from 2 directions to the band-shaped fused portion (end portion) of the polymer sheet via, for example, a reflective mirror. This is because even if the thickness of the sheet is increased, the end portion of the sheet can be further uniformly melted.

In the method for producing a high-melting-point resin fiber, the potential difference generated between the end of the polymer sheet and the collecting member is preferably a high voltage in a range where no discharge occurs, and may be appropriately selected depending on the required fiber diameter, the distance between the electrode and the collecting member, the irradiation amount of laser light, and the like, and is usually about 0.1 to 30kV/cm, preferably 0.5 to 20kV/cm, and more preferably 1 to 10 kV/cm.

The method of applying a voltage to the melted portion of the polymer sheet may be a direct application method in which the laser irradiation portion (band-shaped melted portion of the polymer sheet) and the electrode portion for imparting an electric charge are aligned, but an indirect application method in which the laser irradiation portion and the electrode portion for imparting an electric charge are provided at separate positions (particularly, a method in which the laser irradiation portion is provided on the downstream side in the transport direction of the polymer sheet) is preferable in terms of a simple manufacturing apparatus, efficient conversion of laser light into thermal energy, easy control of the reflection direction of laser light, and high safety. In particular, in the above-described production method, it is preferable that the polymer sheet is irradiated with the band-shaped laser beam on the downstream side of the electrode portion, and the distance between the electrode portion and the laser irradiation portion (for example, the distance between the lower end of the electrode portion and the upper outer edge of the band-shaped laser beam) is adjusted to a specific range (for example, about 10mm or less). The distance is selected according to the electrical conductivity, thermal conductivity, glass transition temperature, laser irradiation amount, etc. of the PEEK resin, and is, for example, about 0.5 to 10mm, preferably about 1 to 8mm, more preferably about 1.5 to 7mm, and particularly preferably about 2 to 5 mm. When the distance between the both is within this range, the molecular mobility of the resin in the vicinity of the laser irradiation portion is improved, and a sufficient charge can be imparted to the resin in a molten state, so that productivity can be improved.

The distance between the end of the polymer sheet (the tip of the taylor cone) and the collecting member is not particularly limited, but is usually 5mm or more, and is preferably 10 to 300mm, more preferably 15 to 200mm, still more preferably 50 to 150mm, and particularly preferably about 80 to 120mm in order to efficiently produce ultrafine fibers.

When the polymer sheet is continuously fed, the conveying speed is not particularly limited, but is usually about 2 to 20mm/min, preferably 3 to 15mm/min, and more preferably 4 to 10 mm/min. If the speed is increased, productivity is improved, but if it is too high, the resin in the vicinity of the laser irradiation portion is not sufficiently melted, and therefore, it is difficult to produce fibers. On the other hand, if the rate is slow, the high melting point resin is decomposed, or the productivity is lowered.

In the above production method, the space between the end of the polymer sheet and the trap member may be an inert gas atmosphere. By setting this space to an inert gas atmosphere, ignition of the fiber can be suppressed, and therefore, the output of the laser can be increased. Examples of the inert gas include nitrogen, helium, argon, and carbon dioxide. Among them, nitrogen gas is generally used. Further, the use of the inert gas can suppress an oxidation reaction in the belt-shaped molten portion.

In addition, the space may be heated. This makes it possible to reduce the fiber diameter of the obtained fiber. That is, by heating the air or inert gas in the space, a rapid temperature decrease of the fiber being formed can be suppressed, and thereby, the elongation or elongation of the fiber is promoted, and a further ultrafine fiber can be obtained. Examples of the heating method include a method using a heater (e.g., a halogen heater) and a method of irradiating laser light. The heating temperature may be selected from a temperature range of, for example, 50 ℃ or higher to a temperature lower than the ignition point of the resin, but is preferably a temperature lower than the melting point of the resin from the viewpoint of spinnability.

[ Polymer sheet ]

The amorphous polymer sheet has a crystallinity of, for example, preferably 25% or less, more preferably 20% or less, and further preferably 15% or less. When the crystallinity is 25% or less, a high-melting resin fiber having low crystallinity can be obtained. The crystallinity of the polymer sheet can be determined by the same method as the crystallinity of the high-melting resin fiber.

Here, the amorphous means: since the molecular skeleton of the resin has bulky molecular chains (sterically hindered molecular chains), the resin cannot be regularly arranged during cooling from a molten state and solidification, and has a property of random molecular arrangement in a solidified state.

The amorphous polymer sheet is preferably low in viscosity in terms of easy formation of ultrafine fibers such as nanofibers, and for example, the viscosity at a shear rate (shear rate) of 121.6(1/s) measured at 400 ℃ is preferably 800Pa · s or less (50 to 800Pa · s), more preferably 600Pa · s or less, and still more preferably 400Pa · s or less. The viscosity at 400 ℃ can be determined by the method described in examples using a capillary rheometer (trade name "CAPILOGRAPH 1D", manufactured by toyoyo seiki). It should be noted that the shear rate (shear rate) can be measured using a capillary rheometer.

The amorphous polymer sheet can be produced by heating and melting an amorphous chip-shaped resin with a T-die extruder or the like, and forming the resin into a sheet. As the amorphous chip-like resin, a commercially available resin can be used, and a trade name of "VESTAKEEP 1000G" (manufactured by Daiiluo-winning Corp.) or the like can be preferably used. The heating temperature of the T-die extrusion molding machine may be equal to or higher than the melting point of the resin, and is, for example, 350 to 400 ℃.

The amorphous polymer sheet may contain various additives used for the fibers, for example, a stabilizer (an antioxidant, an ultraviolet absorber, a heat stabilizer, or the like), a flame retardant, an antistatic agent, a colorant, a filler, a lubricant, an antibacterial agent, an insect and mite preventing agent, a mold inhibitor, a delustering agent, a heat storage agent, a perfume, a fluorescent brightener, a wetting agent, a plasticizer, a thickener, a dispersant, a foaming agent, a surfactant, or the like. These additives may be contained alone or in combination of two or more.

Among these additives, for example, a surfactant is preferably used. When a high voltage is applied to the polymer sheet to inject electric charges, the polymer sheet made of a high-melting-point resin has high electrical insulation, and it is difficult to inject electric charges into the heat-melting portion having a low resistance. However, when a surfactant is used, the electrical resistance of the surface of the fiber having a large electrical insulation property is lowered, and electric charges can be sufficiently injected into the heat fusion portion. The addition of a surfactant or the like is effective for phase separation when a sheet is composed of a plurality of components when a high voltage is applied to a polymer sheet to inject charges.

These additives may be used in a proportion of 50 parts by mass or less, for example, 0.01 to 30 parts by mass, preferably about 0.1 to 5 parts by mass, based on 100 parts by mass of the polymer sheet resin.

[ nonwoven Fabric ]

The nonwoven fabric of the present invention can be produced by the production method described later, or the high-melting resin fiber of the present invention can be produced by another method.

The thickness of the nonwoven fabric of the present invention may be appropriately selected depending on the application, and may be selected from the range of about 0.0001 to 100mm, and is usually about 0.001 to 50mm, preferably about 0.01 to 15mm, and more preferably about 0.05 to 1 mm. Further, the weight per unit area of the nonwoven fabric may be selected depending on the application, and is usually 0.001 to 100g/m²About 0.05 to 50g/m is preferable²More preferably 0.1 to 10g/m²Left and right. In the nonwoven fabric of the present invention, in the method for producing a nonwoven fabric described later, the fiber diameter, thickness, basis weight, and other shapes of the nonwoven fabric to be produced can be controlled by adjusting the sheet conveyance speed, laser intensity, movement speed of the collecting member, and the like.

The nonwoven fabric of the present invention may be subjected to post-processing treatment such as charging treatment by electret processing, plasma discharge treatment, corona discharge treatment, sulfonation treatment, and hydrophilization treatment by graft polymerization or the like, depending on the purpose. The nonwoven fabric may be further subjected to secondary processing, or may be laminated and integrated with other nonwoven fabrics (for example, spun-bonded nonwoven fabrics) or knitted fabrics, films, plates, substrates, and the like.

[ method for producing nonwoven Fabric ]

Next, an example of a method for producing a nonwoven fabric will be described. In the following method for producing a nonwoven fabric, the position where the fibers flying in the direction of the fiber collecting plate are collected can be moved with time, and the production of the high-melting-point resin fibers can be continuously performed.

Here, as a method of moving the collection position of the fibers flying in the direction of the fiber collection plate with time, for example: (1) a method of moving the collecting member (the fiber collecting plate when the fiber collecting plate itself functions as the collecting member); (2) a method of moving the holding position of the polymer sheet; (3) a method of applying a mechanical, magnetic or electrical force to the fibers in flight from the taylor cone toward the collecting member, for example, a method of blowing air into the fibers in flight; (4) a method in which the methods (1) to (3) are selectively combined.

Among them, the method (1), i.e., the method in which the collecting member is moved, is preferable in that the structure of the apparatus can be simplified and the shape (thickness, basis weight, etc.) of the nonwoven fabric to be produced can be easily controlled. Hereinafter, a method for producing a nonwoven fabric will be described in detail, taking as an example the case of using the method (1) described above.

In the method for producing a nonwoven fabric using the method (1), in the production method shown in fig. 1, the collection member is placed on the fiber collection plate 8, and the collection member is moved in a direction perpendicular to the width direction of the polymer sheet 6 (in the drawing, the right direction or the left direction), and the production of the high-melting-point resin fibers of the present invention is continuously performed. Here, the movement speed of the collection member may be constant or may change with time, and the movement and the stop may be repeated. In order to continuously produce the high-melting-point resin fibers of the present invention, as described above, the polymer sheet 6 may be continuously fed to the fiber collecting plate 8 (collecting member) as the fiber production process proceeds. The speed (conveying speed) at which the polymer sheet is continuously fed out is as described in the method for producing high-melting-point resin fibers.

The moving speed of the collecting member on the fiber collecting plate 8 is not particularly limited, and may be appropriately determined in consideration of the weight per unit area of the produced fiber sheet, and is usually about 10 to 2000 mm/min. For example, a weight per unit area of 1000G/m²When the transport speed of the polymer sheet of (2) is 0.5mm/min, the moving speed of the collecting member is set to about 1000mm/min, whereby a continuous production of a weight per unit area of 0.5G/m can be achieved²Left and right nonwoven fabrics.

Fig. 3 is a cross-sectional view schematically showing an example of a nonwoven fabric manufacturing apparatus including the method for manufacturing the high-melting-point resin fiber shown in fig. 1. The apparatus shown in fig. 3 includes: a laser light source 11, an optical path adjusting member 12, a polymer sheet conveying device 13 that continuously sends out a polymer sheet 6, a holding member 16 that holds the polymer sheet 6, an electrode 17 that applies an electric charge to the polymer sheet 6, a collecting member 22 for collecting fibers, a fiber collecting plate 14 that faces the electrode 17 across a band-shaped fusion zone (end) 6a of the polymer sheet 6 and the collecting member 22, a case 23 in which a heating device 15 is disposed, high

voltage generating devices

20a and 20b that apply voltages to the electrode 17 and the fiber collecting plate 14, respectively, and a pulley 21 that moves the collecting member 22. The optical path adjusting member 12 is an assembly of optical components as described above, and is formed by a beam expander and homogenizer 2, a collimator lens 3, a cylindrical lens 4, and the like shown in fig. 1.

In fig. 3, a band-shaped laser beam 5 emitted from a laser light source 11 and passing through an optical path adjusting member 12 is introduced into a case 23, and irradiates a band-shaped fusion zone (end portion) 6a of a polymer sheet 6. A polymer sheet conveying device 13 including a motor and a mechanism for converting a rotational motion of the motor into a linear motion is attached to an upper portion of the casing 23, and the polymer sheet 6 is attached to the polymer sheet conveying device 13 and continuously fed into the casing 23. On the other hand, the lower portion of the polymer sheet 6 is held by a holding member 16 to which an electrode 17 is attached. Since the polymer sheet 6 and the electrode 17 are always in contact with each other, when a voltage is applied to the electrode 17, an electric charge is applied to the polymer sheet 6.

The fiber collecting plate 14 paired with the electrode 17 (functioning as an electrode paired with the electrode 17) is disposed at a position facing the electrode 17 with the band-shaped fusion zone (end) 6a of the polymer sheet 6 and the collecting member 23 interposed therebetween. Therefore, when a voltage is applied to the electrode 17 and the fiber collecting plate 14, a potential difference is generated between the band-shaped fused portion (end portion) 6a of the polymer sheet 6 and the collecting member 22. The application of voltage to the electrode 17 and the fiber collecting plate 14 is performed by high

voltage generating devices

20a and 20b connected to each other. In this nonwoven fabric production apparatus, the electrode 17 is a positive electrode and the fiber collecting plate 14 is a negative electrode, but the opposite may be true. The collecting member 22 is a belt conveyor formed of the pulley 21 and a conveyor belt, and the conveyor belt itself corresponds to the collecting member 22. Therefore, the collecting member 22 (conveyor belt) moves in a predetermined direction (for example, right direction in the figure) as the pulley 21 is driven.

The nonwoven fabric manufacturing apparatus shown in fig. 3 includes a heating device 15, and is capable of heating fibers that are ejected from the ribbon-shaped melting section (end section) 6a of the polymer sheet 6 toward the collecting member 23 and are stretched. The case 23 includes a laser absorbing plate 19 and a heat absorbing plate 18.

In the nonwoven fabric manufacturing apparatus shown in fig. 3, in a state where a voltage is applied to both the electrode 17 and the fiber collection plate 14, the polymer sheet 6 is conveyed by the polymer sheet conveying apparatus 13 and the holding member 16, and the band-shaped fused portion (end portion) 6a of the polymer sheet 6 is irradiated with the band-shaped laser 5, whereby, as described above, a taylor cone is formed in the band-shaped fused portion (end portion) 6a of the polymer sheet 6, and the fiber is ejected from the taylor cone and flies above the fiber collection plate 14, and as a result, the elongated fiber is collected by the collection member 22. Further, by continuously conveying the polymer sheet 6 (continuously ejecting the fibers) and moving the collection member 22, a nonwoven fabric can be produced on the collection member 22.

In the nonwoven fabric manufacturing apparatus shown in fig. 3, the collecting member 22 is a sheet-like member. In this apparatus, the collecting member 22 is not particularly limited as long as it is in the form of a sheet, and may be paper, a film, various woven fabrics, a nonwoven fabric, a mesh, or the like. In addition, the trapping member may be a metal or a sheet or a belt having a surface resistance value of the same degree as that of the metal.

In the nonwoven fabric production apparatus shown in fig. 3, the materials of the electrode 17 and the fiber collecting plate 14 may be any conductive material (usually, a metal component), and examples thereof include: a group VIB element such as chromium, a group VIIIB metal element such as platinum, a group IB element such as copper or silver, a group IIB element such as zinc, a group IIIA element such as aluminum, a metal monomer or alloy (aluminum alloy, stainless steel alloy, or the like), or a compound containing these metals (a metal oxide such as silver oxide, aluminum oxide, or the like). These metal components may be used alone or in combination of two or more. Among these metal components, copper, silver, aluminum, stainless steel alloy, and the like are particularly preferable. The shape of the fiber collecting plate 14 is not particularly limited, and examples thereof include a plate shape, a roll shape, a belt shape, a net shape, a saw shape, a wave shape, a needle shape, and a thread shape. Of these shapes, a plate shape and a roller shape are particularly preferable. Examples of the laser absorbing plate 19 include a metal coated with a black body, a porous ceramic, and the like. The heat absorbing plate 18 may be made of, for example, black ceramic. By using such an apparatus, the high melting point resin fiber and nonwoven fabric of the present invention can be efficiently produced.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

(preparation of Polymer sheet)

Polymer sheets A to D were produced by the following method.

Using a T die extrusion molding apparatus (manufactured by Toyo Seiki Seisaku-Sho Seisakusho Co., Ltd.) of a test plasticator (Labo Plastomill), a chip-like sample of PEEK resin, which is a high-melting resin described below, was extruded into a sheet shape at an extrusion temperature of 345 to 360 ℃ using a T die having a die width of 150mm and a crack width of 0.4mm, and the sheet was wound at a take-up roll temperature of 140 ℃ and a winding speed of 1.0 to 2.0m/min to manufacture polymer sheets A to D having a thickness of 0.1 mm. The polymer sheets B, C and D were molded by an extruder and then heat-treated at 230 ℃ for 20 minutes.

The crystallinity and viscosity at 400 ℃ at a shear rate (shear rate) of 121.6(1/s) of the polymer sheet thus produced were as follows. The viscosity is measured by the following method for measuring the viscosity of a polymer sheet, and the crystallinity is determined by the same method as the crystallinity of the high-melting-point resin fiber described below.

Polymer sheet a: VESTAKEEP 1000G (amorphous sample material: degree of crystallinity 12.7%, viscosity 151Pa · s)

Polymer sheet B: VESTAKEEP 1000G (crystalline sample material: crystallinity 35.5%, viscosity 151Pa · s)

Polymer sheet C: VESTAKEEP 3300G (crystalline sample material: crystallinity 36.7%, viscosity 761Pa · s)

Polymer sheet D: VESTAKEEP 4000G (crystalline sample material: degree of crystallinity 37.7%, viscosity 1012 Pa. s)

(method of measuring the viscosity of Polymer sheet)

The viscosity measured at 400 ℃ at a shear rate (shear rate) of 121.6(1/s) was measured using a capillary rheometer (trade name "CAPILOGRAPH 1D", manufactured by Toyo Seiki Seisaku-sho Ltd.) with a jig having a capillary diameter of 1mm and a length of 10 mm.

Next, in examples 1 to 3 and comparative examples 1 to 5, using the polymer sheets a to D produced by the above-described methods, high-melting resin fibers were produced by the following method. The polymer sheets used in examples 1 to 3 and comparative examples 1 to 5, the transport speed of the polymer sheets, the output of the laser beam, the crystallinity of the obtained high-melting resin fiber, and the fiber diameter (diameter) are shown in table 1. In comparative examples 2 and 5, no fibers could be obtained.

(production of high melting resin fiber)

High-melting resin fibers of examples 1 to 3 and comparative examples 1 to 5 were produced by using an apparatus shown schematically in FIG. 1.

As the laser light source 1 of the apparatus shown in FIG. 1, CO was used₂Laser (manufactured by Universal Laser System Co., Ltd., wavelength: 10.6 μm, output: 45W, air-cooled type, beam diameter)Phi 4 mm). An optical path adjusting member may be used in which the following are arranged at predetermined positions in the following order: a beam expander and homogenizer (with an incident beam diameter of phi 12mm (design value) and an outgoing beam diameter of phi 12mm (design value)) having a magnification of 2.5 times that of the beam expander and homogenizer 2; a collimator lens (an incident beam diameter phi 12mm (design value) and an outgoing beam diameter phi 12mm (design value)) as the collimator lens 3; a cylindrical lens (plano-concave lens, F-30mm) and a cylindrical lens (plano-convex lens, F-300mm) as the cylindrical lens group 4. By providing these optical path adjusting members, the spot-like laser light is converted into a band-like laser light having a width of about 150mm and a thickness of about 1.4mm, and the band-like melted portion (end portion) 6a of the polymer sheet 6 is irradiated with the laser light. Thus, a high-melting resin fiber was obtained.

(method of measuring the crystallinity of a high-melting resin fiber)

The crystallinity of the high-melting resin fiber was calculated from the heat quantity obtained by DSC measurement.

DSC measurement was carried out using a differential scanning calorimeter (manufactured by DSC-Q2000/TA Co.), alumina as a reference material, under a nitrogen atmosphere, at a temperature ranging from 0 ℃ to 420 ℃ and at a temperature rise rate of 20 ℃/min.

Then, the crystallinity was determined from the heat amount obtained by DSC measurement using the following formula.

Degree of crystallization (%) { (heat of fusion of sample) - (heat of recrystallization of sample) }/heat of fusion of complete crystallization (130J/G) × 100

[ Table 1]

Industrial applicability

The high-melting-point resin fiber of the present invention is very fine and has excellent heat resistance and chemical resistance, and therefore, the nonwoven fabric obtained using the fiber can be used as a separator for a fuel cell, a filter for medical materials, a space material, and the like.

Claims

1. A high-melting-point resin fiber having a crystallinity of 30% or less and a diameter of 4 μm or less and made of PEEK,

wherein the high-melting resin fiber is obtained as follows:

a high-melting-point resin fiber is obtained by irradiating a polymer sheet made of PEEK having a crystallinity of 15% or less with a band-shaped laser beam to heat and melt an end of the polymer sheet in a linear shape, and by providing a potential difference between the melted band-shaped melted portion and a fiber collecting plate, forming a needle-shaped protruding portion in the band-shaped melted portion of the polymer sheet, flying fibers discharged from the needle-shaped protruding portion in the direction of the fiber collecting plate, and collecting the fibers on the fiber collecting plate or a collecting member interposed between the melted portion and the fiber collecting plate.

2. The high-melting-point resin fiber according to claim 1, wherein the polymer sheet has a conveying speed of 2 to 20 mm/min.

3. The high-melting resin fiber according to claim 1 or 2, wherein the potential difference is 0.1 to 30 kV/cm.

4. A high-melting resin fiber according to claim 1 or 2, wherein the polymer sheet has a viscosity of 800Pa · s or less as measured at 400 ℃ at a shear rate of 121.61/s.

5. A nonwoven fabric obtained from the high-melting resin fiber according to claim 1.