JP2018138709A - Polypropylene nanofiber and method of producing laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a polypropylene nanofiber using not an electric field, but a high-speed high-temperature gas.SOLUTION: A method of producing a polypropylene nanofiber comprises: a process (A) of discharging molten polypropylene from a discharge nozzle and a process (B) of stretching the molten polypropylene by ejecting a high-speed high-temperature gas from a gas nozzle to form the nanofiber, in which a melt flow rate of the polypropylene is 300-3000 g/10 minutes at 230°C and with a load of 21.18 N.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polypropylene nanofiber and a method for producing a laminate.

Conventional technology

  Conventionally, polypropylene fibers have been produced by melt spinning. However, it has been difficult to produce ultrafine polypropylene fibers by the melt spinning method, and in particular, it has been difficult to stably obtain fibers having a diameter of 20 μm or less (single fiber fineness of about 3 dtex). On the other hand, an electrospinning method is known as a method for producing ultrafine fibers. A melt electrospinning method that does not use a solvent during spinning has also been proposed (Patent Document 1: Japanese Patent Application Laid-Open No. 2007-32246), and attempts have been made to apply a propylene-based resin composition to the melt electrospinning method ( Patent Document 2: JP 2011-162636 A and Patent Document 3: JP 2009-133303). However, in these methods, it is difficult to make the polymer melt into ultrafine fibers due to electrolytic interference due to high voltage. On the other hand, Patent Document 4 (Japanese Unexamined Patent Application Publication No. 2016-156114) discloses a method for producing a nanofiber sheet that does not use electrolysis. However, a method for producing polypropylene-only nanofibers is not specifically disclosed.

JP 2007-32246 A JP 2011-162636 A JP 2009-133039 A JP 2016-156114 A

  The inventors conducted a trial operation of the method described in Patent Document 4 using various polypropylenes, and found that it was difficult to produce nanofibers without using specific polypropylenes. In view of such circumstances, an object of the present invention is to provide a method for producing polypropylene nanofibers using a high-speed high-temperature gas without using an electric field.

The inventors have found that polypropylene having a specific melt flow rate (MFR) solves the problem. Therefore, the said subject is solved by the following this invention.
[1] Step (A): A step of discharging molten polypropylene from a discharge nozzle, and Step (B): A step of discharging high-speed high-temperature gas from a gas nozzle to stretch the molten polypropylene to form nanofibers,
A method for producing polypropylene nanofibers comprising:
The manufacturing method whose melt flow rate (230 degreeC, load 21.18N) of the said polypropylene is 300-3000 g / 10min.
[2] Step (A): A step of discharging molten polypropylene from the discharge nozzle,
Step (B): A step of forming nanofibers by discharging a high-speed high-temperature gas from a gas nozzle to stretch the molten polypropylene.
Step (C): a step of providing a polypropylene nanofiber layer by adhering the polypropylene nanofibers to a substrate disposed at a position facing the discharge nozzle or the gas nozzle,
A method for producing a laminate comprising:
The manufacturing method whose melt flow rate (230 degreeC, load 21.18N) of the said polypropylene is 300-3000 g / 10min.
[3] Step (D): a step of discharging a molten polymer from the second discharge nozzle, discharging a high-speed high-temperature gas from the second gas nozzle, and stretching the molten polymer to form a second nanofiber.
Step (E): a step of attaching a second nanofiber on the polypropylene nanofiber layer formed in the step (C),
The method for producing a laminate according to [2], further comprising:
[4] Step (A ′): a step of discharging a molten polymer other than polypropylene from the discharge nozzle,
Step (B ′): a step of discharging a high-speed high-temperature gas from a gas nozzle and stretching the molten polymer to form nanofibers;
Step (C ′): a step of providing a nanofiber layer by adhering the nanofiber to a substrate disposed at a position facing the discharge nozzle or the gas nozzle,
Step (D ′): a step of discharging the polypropylene according to claim 1 from a second discharge nozzle, discharging a high-speed high-temperature gas from the second gas nozzle, and stretching the polypropylene to form polypropylene nanofibers. ,
Step (E ′): A method for producing a laminate including a step of attaching the polypropylene nanofibers formed in the step (D ′) on the nanofiber layer formed in the step (C ′).
[5] The production method according to any one of [1] to [4], wherein the polypropylene used in the nanofiber formation step does not contain an additive.

  According to the present invention, it is possible to provide a method for producing polypropylene nanofibers using a high-speed high-temperature gas without using an electric field.

Schematic diagram showing a method for producing polypropylene nanofibers of the present invention Schematic diagram showing a method for producing a laminate of the present invention

  Hereinafter, the present invention will be described in detail. In the present invention, “X to Y” includes X and Y which are end values.

1. Manufacturing method of polypropylene nanofiber The manufacturing method includes a step (A): a step of discharging molten polypropylene from a discharge nozzle, and a step (B): discharging the high-speed high-temperature gas from the gas nozzle and stretching the molten polypropylene to form nanofibers. The process of forming is provided. The speed of the gas to be discharged is not particularly limited, but is preferably 4 to ³⁰ Nm ³ / min / m, and the temperature is preferably in the range of 250 to 350 ° C.

(1) Polypropylene In the present invention, polypropylene means a polypropylene homopolymer, a polypropylene copolymer of propylene and less than 10 mol% of an α-olefin, a composition containing the homopolymer, or a composition containing the copolymer. Say. Specifically, i) a polypropylene homopolymer, ii) a polypropylene copolymer containing less than 10 mol% of α-olefin units obtained by polymerizing propylene and α-olefin, a resin composition containing i), ii ), A resin composition comprising i) and ii), a resin composition comprising i) and ii), and the like. The resin composition may contain an additive described later.

  The melt flow rate (hereinafter also simply referred to as “MFR”) measured at 230 ° C. and a load of 21.18 N of the polypropylene used in the present invention is 300 to 3000 g / 10 minutes. If the MFR is less than the lower limit, the polymer cannot be sufficiently stretched to the nano level. When the MFR exceeds the upper limit, fiber breakage or the like occurs. In this respect, the MFR is preferably 500 to 3000 g / 10 minutes, and more preferably 1000 to 3000 g / 10 minutes.

The polypropylene used in the present invention preferably has a xylene insoluble content of 95% by weight or more, and more preferably has the following characteristics.
1) The melting peak temperature (Tm) measured by the DSC (differential scanning calorimeter measurement) method of the xylene-insoluble content is higher than 150 ° C and lower than 170 ° C.
2) The molecular weight distribution (Mw / Mn) of xylene insolubles is 2.0 to 5.0.
3) The stereoregularity (mmmm) of the xylene-insoluble matter is 95.0 to 99.5%.

  The component insoluble in xylene of polypropylene corresponds to an isotactic component that is crystalline. On the other hand, a component soluble in xylene contained in a small amount in polypropylene corresponds to an amorphous atactic component and has a lower molecular weight than a component insoluble in xylene. Therefore, the melting characteristics of polypropylene and the physical properties of molded articles are mainly influenced by components insoluble in xylene.

  That the amount of xylene insolubles in polypropylene is 95% by weight or more means that the crystalline component of polypropylene is 95% by weight or more. The amount of xylene insolubles is more preferably 96% by weight or more, and still more preferably 97% by weight or more. When the crystalline component of polypropylene is less than 95% by weight, fibers tend to be misattached and spinning may be difficult.

  Tm of the crystalline component of polypropylene is measured as a melting peak temperature by DSC (differential scanning calorimetry), and the temperature is preferably higher than 150 ° C. and lower than 170 ° C. The lower limit of Tm is preferably 152 ° C. or higher, and more preferably 154 ° C. or higher. The upper limit of Tm is preferably 165 ° C. or lower. If the Tm of the crystalline component of polypropylene is less than 150 ° C., the heat resistance of the fiber is insufficient, and if it exceeds 170 ° C., crystallization at higher temperatures may result in difficulty in spinning.

  The molecular weight distribution (Mw / Mn) of the crystalline component of polypropylene is preferably 2.0 to 5.0. When Mw / Mn exceeds 5.0, it may be difficult to obtain ultrafine fibers due to the ballast effect. The stereoregularity (mmmm) of the crystalline component of polypropylene is preferably 95.0 to 99.5%. If the mmmm is less than 95.0%, the strength and heat resistance of the fiber may decrease.

  The polypropylene used in the present invention comprises (a) a solid catalyst component containing magnesium, titanium, halogen and an internal electron donor compound as essential components, (b) an organoaluminum compound, and (c) a catalyst containing an external electron donor compound. Can be obtained by polymerizing the monomer using Known components can be used as these components. However, from the viewpoint of achieving a relatively high MFR, the internal electron donor compound is preferably 1,3-diether. Or you may manufacture the polypropylene used by this invention using a metallocene catalyst.

  Polypropylene used in the present invention is an oil extender, antioxidant, nucleating agent, filler, chlorine absorbent, heat stabilizer, light stabilizer, ultraviolet absorber, internal lubricant, external lubricant, anti-blocking agent, antistatic agent Olefin polymers such as agents, antifogging agents, flame retardants, organic and inorganic pigments, dyes, dispersants, copper damage prevention agents, neutralizing agents, plasticizers, foaming agents, antifoaming agents, crosslinking agents, peroxides, etc. May contain conventional additives and pigments commonly used in the art. However, in consideration of spinning, it is more preferable that no additive is contained.

(2) Step (A)
This process will be described with reference to FIG. In FIG. 1, 20 is a molten polypropylene, 22 is a discharge nozzle, 10 is a gas, and 12 is a gas nozzle. In this step, the molten polypropylene 20 is discharged from the discharge nozzle 22. Although the temperature to discharge will not be limited if it is the temperature which a polypropylene fuse | melts, it is preferable that it is 200-300 degreeC. The nozzle diameter is not particularly limited, and a commercially available nozzle used for spinning such as ordinary melt blown can be used, but it is preferably 1000 μm or less, more preferably 250 μm or less, and further preferably 100 μm or less. If the nozzle diameter is too large, a thin fiber diameter cannot be obtained. On the other hand, if the nozzle diameter is too small, it is difficult to work on the nozzle and pressure loss increases.

(3) Process (B)
In this process, the high-speed high-temperature gas 10 is discharged from the gas nozzle 12 to the molten polypropylene 20 to stretch the molten polypropylene 20 to form nanofibers. A nanofiber is a fiber having an average fiber diameter in the nano order, specifically, a fiber having a diameter of less than 1000 nm, preferably 500 nm or less, more preferably 300 nm or less. The average fiber diameter is measured by observing the fiber with an electron microscope or the like.

  In this step, it is preferable not to cool the molten polypropylene 20 excessively. Therefore, the gas 10 is high temperature, for example, about 200 to 300 ° C. The fiber diameter can be appropriately adjusted by the speed of the gas 10. Accordingly, the gas 10 is discharged at a high pressure so that a desired flow rate can be achieved. Although it does not specifically limit as a high pressure gas, The compressed gas of 0.5-0.7 Mpa can be used. In this way, the molten polypropylene 20 rides on the flow of the gas 10, and polypropylene nanofibers are formed in the gas 10 discharge direction. In order to prevent the diffusion of the propylene nanofibers, a scattering prevention cover may be provided around the streamline of the propylene nanofibers. The gas is preferably an inert gas such as nitrogen or air.

  The polypropylene nanofiber of the present invention is useful as a raw material for a laminate described later, a medical carrier, a medical medium such as a cell culture medium, and a raw material for a heat-insulating woven fabric.

2. Manufacturing method of a laminated body The said method is demonstrated with reference to FIG. In FIG. 2, 24 is a polypropylene nanofiber layer, 40 is a second nanofiber, 42 is a second discharge nozzle, 30 is a second high-speed high-temperature gas, 32 is a second gas nozzle, and 50 is a substrate. The laminate of the present invention is manufactured through the step (C) in which the polypropylene nanofibers manufactured by the above method are attached to the base material 50 provided at the position where the discharge nozzle 22 or the gas nozzle 12 faces. In FIG. 2, since the base material 50 can move downward in the drawing, the thickness of the layer can be adjusted by its speed. Thus, the laminated body which has the polypropylene nanofiber layer 24 on the base material 50 can be manufactured. The kind of the base material 50 is not limited, For example, a polymer sheet, paper, glass, metal foil, etc. can be used. The discharge nozzle 22 and the gas nozzle 12 are arranged at an angle. In FIG. 2, the base material 50 is disposed so as to face the gas nozzle 12. However, the base material 50 may be disposed so as to face the discharge nozzle 22 by changing the positions of the discharge nozzle 22 and the gas nozzle 12.

  Furthermore, after the polypropylene nanofiber layer 24 is formed, a second nanofiber can be formed from the second polymer 40 and adhered to the polypropylene nanofiber layer 24 to form a second nanofiber 44 layer. it can. Since the second nanofiber is in a high temperature state, it is thermally fused to the polypropylene nanofiber layer 24. That is, the polypropylene nanofiber layer 24 can be used as an adhesive layer. The second nanofiber can be formed in the same manner as the polypropylene nanofiber using the second discharge nozzle 42 and the second gas nozzle 32. The second polymer may be a known polymer. Examples of the polymer include polyester, polyamide, polyolefin, polystyrene, polyvinyl chloride, polylactic acid, an ethylene copolymer, a polyolefin-modified resin, polyurethane (PU), and the like, or a combination thereof. However, when the polyolefin is polypropylene, the polypropylene has a MFR of 300 to 3000 g / 10 min.

  Further, by the same method, instead of polypropylene having a MFR of 300 to 3000 g / 10 min (also referred to as “polypropylene of specific MFR”), an adhesive layer made of nanofibers is formed using the second polymer, A nanofiber layer using a specific MFR polypropylene can be formed thereon.

  The laminate of the present invention is useful as a separation material such as a filter and a mask, plant soil and the like.

The present invention will be further described below with reference to examples. Each analysis in the examples is as follows.
[MFR]
According to JIS K 7210, the measurement was performed under conditions of a temperature of 230 ° C. and a load of 21.18 N.

[Amount of insoluble xylene in polypropylene resin material]
2.5 g of polymer was dissolved in 250 ml of xylene at 135 ° C. with stirring. After 20 minutes, the solution was cooled to 25 ° C. with stirring and then allowed to stand for 30 minutes. The precipitate was filtered through filter paper, the solution was evaporated in a stream of nitrogen, and the residue was dried at 80 ° C. under vacuum until a constant weight was reached. The weight percent of xylene soluble polymer at 25 ° C. was thus calculated. The amount of xylene insolubles (% by weight of the polymer insoluble in xylene at 25 ° C.) is determined by (100−% by weight of the soluble polymer) and is considered to be the amount of the isotactic component of the polymer.
The xylene-insoluble matter was collected by thoroughly washing off xylene remaining in the precipitate with methanol and then drying it at 80 ° C. under vacuum.

[Melting point of xylene insoluble matter (Tm)]
The melting point of xylene-insoluble matter obtained by the above method was crystallized by using a diamond DSC manufactured by PerkinElmer Co., Ltd., holding the sample at 230 ° C. for 5 minutes, and then cooling to 30 ° C. at a cooling rate of 10 ° C./min. After maintaining at 30 ° C. for 5 minutes, it was determined by the peak position of the melting curve obtained when heated to 230 ° C. at a temperature rising rate of 10 ° C./min. In the case of low molecular weight polypropylene, there may be a sub-melting peak due to the melting of crystals caused by melting recrystallization during temperature rise on the high temperature side of the main melting peak, but the melting point used in the present invention is It calculated | required from the position of the melting peak.

[Molecular weight distribution of xylene insoluble matter (Mw / Mn)]
The molecular weight distribution (Mw / Mn) of the xylene-insoluble matter obtained by the above method was measured by gel permeation chromatography (PL-GPC220 manufactured by Polymer Laboratories). In the GPC measurement in the present invention, 1,2,4-trichlorobenzene containing an antioxidant is used as the mobile phase, and the same solvent as the mobile phase is used as the solvent of the polymer sample solution, and the sample concentration is 1 mg / mL. The sample was prepared by dissolving for 2 hours while shaking at a temperature of 150 ° C. 200 μL of the sample solution thus obtained was injected into the column and measured at a flow rate of 1.0 mL / min, a temperature of 140 ° C., and a data acquisition interval of 1 second.

[Tacticity of xylene-insoluble matter (mmmm)]
The mmmm insoluble matter mmmm obtained by the above method was determined as follows. First, a sample dissolved in a mixed solvent of 1,2,4-trichlorobenzene / deuterated benzene was measured by ¹³ C-NMR method using JNM LA-400 (13C resonance frequency 100 MHz) manufactured by JEOL. Subsequently, from the obtained spectrum, the ratio of the intensity of the peak corresponding to the pentad in which four meso (m) bond sequences of the propylene monomer were consecutively obtained was calculated as follows. It was determined according to the method described in Zambelli, Macromolecules, 6, 925 (1973).

[Average fiber diameter]
The spun fiber diameter is observed using a JSM-6510LA (low vacuum analysis scanning electron microscope apparatus) manufactured by JEOL Ltd., and the average fiber diameter is measured.

[Example 1]
(1) Production of polypropylene 1 Powdered homopolypropylene: Polypropylene 1 (MFR = 1750 g / 10 min, xylene insoluble content at 25 ° C. = 97.7 wt%, xylene insoluble Tm = 160 ° C., Mw / Mn = 4.5 in xylene-insoluble matter, mmmm = 98.4% in xylene-insoluble matter).
1) Preparation of solid catalyst component In accordance with Example 1 of European Patent Application EP 728769, component (A) (solid catalyst component) was prepared. Specifically, component (A) was prepared as follows.
225 ml of TiCl ₄ was introduced at 0 ° C. into a 500 ml reactor equipped with a porous barrier. While stirring the contents, 10.1 (54 mmol) g of microspherical MgCl ₂ .2.1C ₂ H ₅ OH was added for 15 minutes under a nitrogen atmosphere. A method for producing the MgCl ₂ .2.1C ₂ H ₅ OH will be described later. At the end of the addition, the temperature was brought to 70 ° C., 9 mmol of 9,9-bis (methoxymethyl) fluorene was added, the contents were heated to 100 ° C. and reacted at this temperature for 2 hours. Thereafter, TiCl ₄ was removed by filtration. 200 ml of TiCl ₄ and 9 mmol of 9,9-bis (methoxymethyl) fluorene were newly added and the contents were reacted at 120 ° C. for 1 hour. Thereafter, it is filtered again and 200 ml of TiCl ₄ is newly added, and the content is further reacted at 120 ° C. for 1 hour, followed by filtration at 60 ° C. until no chlorine ions are present in the furnace liquid. Washed with heptane. The solid component was analyzed and found to contain 3.5 wt% Ti and 16.2 wt% 9,9-bis (methoxymethyl) fluorene.

A microspherical MgCl ₂ .2.1C ₂ H ₅ OH adduct was prepared as follows. 48 g MgCl ₂ , 77 g anhydrous C ₂ H ₅ OH, and 830 ml kerosene were introduced into a 2 liter autoclave equipped with a turbine stirrer and dip pipe at ambient temperature under an inert gas atmosphere. When the contents were heated to 120 ° C. with stirring, an adduct was formed between MgCl ₂ and the alcohol. The adduct was melted and mixed with the dispersant. The inside of the autoclave was maintained at a nitrogen pressure of 15 atm. The immersion pipe of the autoclave was heated to 120 ° C. from the outside by a heating jacket. The inner diameter of the heating jacket was 1 mm, and the length from end to end was 3 m. The mixture was circulated through the pipe at a speed of 7 m / sec. The dispersion was collected in a 5 liter flask with stirring. The flask contained 2.5 liters of kerosene and was cooled from the outside by a jacket maintained at an initial temperature of −40 ° C. The final temperature of the emulsion was 0 ° C. The spherical solid product constituting the dispersed phase of the emulsion was separated by settling and filtration, then washed with heptane and dried. All the above operations were performed in an inert atmosphere. 130 g of MgCl ₂ .3.0C ₂ H ₅ OH was obtained in the form of solid spherical particles with a maximum diameter of 50 μm or less. The product is then removed by gradually raising the temperature from 50 ° C. to 100 ° C. in a nitrogen stream until the alcohol content is 2.1 moles per mole of MgCl _2.

2) Polymerization In a pre-contact vessel, in 80 ml of anhydrous n-hexane, 0.5 mg of dicyclopentylmethoxysilane (DCPMS) and 7 mmol of triethylaluminum (TEAL) were added to 7 mg of the solid catalyst component obtained above. Contact was made at 10 ° C. for 20 minutes. The resulting catalyst system was prepolymerized by introducing it into a 4 liter stainless steel autoclave equipped with a horseshoe stirrer and purged with nitrogen flow for 1 hour and kept in suspension in liquid propylene at 20 ° C. for 10 minutes. Went. Subsequently, hydrogen (used for the purpose of MFR adjustment) was supplied to liquid propylene at 15000 mol ppm, and the content was polymerized at a polymerization temperature of 70 ° C. using the obtained prepolymer. Thereafter, the unreacted monomer was removed, and the polymer was recovered and dried in an oven at 70 ° C. for 3 hours under a nitrogen flow. In this way, polypropylene 1 was produced.

(2) Production of Laminate Using the apparatus shown in FIG. 1, the polypropylene is heated to 250 ° C., and the molten polypropylene 20 is discharged from the discharge nozzle 22. The pressurized gas 10 heated to 250 ° C. is discharged from the gas nozzle 12 and the molten polypropylene 20 is stretched to form polypropylene nanofibers. The polypropylene nanofibers are attached to the substrate 50 to obtain a laminate. The average fiber diameter of the polypropylene nanofiber is 500 nm.

[Example 2]
(1) Production of Polypropylene 2 Powdered homopolypropylene: Polypropylene 2 (MFR = 1800 g / 10 min, xylene insoluble content at 25 ° C. = 98.7 wt%, xylene insoluble content Tm = 154 ° C., xylene-insoluble matter Mw / Mn = 2.5, xylene-insoluble matter mmmm = 96.7%).
1) Preparation of catalyst component A catalyst system was prepared by the method described in PCT / EP2004 / 00761. However, instead of rac-dimethylsilylbis (2-methyl-4,5-benzoindenyl) zirconium dichloride, rac-dimethylsilylene (2-methyl-4- (2-methyl-4- ( 4′-tert-butylphenyl) indenyl) (2-isopropyl-4- (4′-tert-butylphenyl) indenyl) zirconium dichloride was used.

2) Polymerization The catalyst system in the form of catalyst mud prepared as described above was fed into a pre-contact vessel and diluted with about 5 (kg / hr) propane therein. The catalyst system was fed from a pre-contact vessel to the pre-polymerization loop, where propylene was fed simultaneously. The temperature in the prepolymerization loop was 45 ° C. and the catalyst residence time was 8 minutes. The prepolymerization catalyst obtained in the prepolymerization loop is then continuously fed into the loop reactor, propylene is fed, and hydrogen (used for MFR adjustment) is fed to 900 mol ppm. The polymerization was carried out at a polymerization temperature of 70 ° C. The polymer was removed from the reactor, separated from unreacted monomer and dried in an oven at 70 ° C. under a stream of nitrogen for 3 hours.

(2) Manufacture of laminate A laminate of polypropylene nanofibers is obtained in the same manner as in Example 1 except that polypropylene 2 is used. The average fiber diameter of the polypropylene nanofiber is 300 nm.

[Comparative Example 1]
Powdery homopolypropylene 3 obtained in the same manner as homopolypropylene 1 except that hydrogen was supplied at 4000 mol ppm instead of homopolypropylene 1 (MFR = 200 g / 10 min, xylene insoluble content at 25 ° C. The laminate is produced in the same manner as in Example 1 except that the amount of 9 = 98.0 wt% is used. However, in this example, the average fiber diameter of the polypropylene fiber is 1500 nm and does not become a nanofiber.

[Comparative Example 2]
Instead of homopolypropylene 1, powdery homopolypropylene 4 obtained in the same manner as homopolypropylene 1 except that hydrogen was supplied to 23000 molppm without using DCPMS (MFR is too high to be measured). A laminated body is produced in the same manner as in Example 1 except that it is used. However, in this example, fiber breakage occurs and polypropylene fibers cannot be obtained.

DESCRIPTION OF SYMBOLS 10 Gas 12 Gas nozzle 20 Molten polypropylene 22 Discharge nozzle 24 Polypropylene nanofiber layer 30 2nd gas 32 2nd gas nozzle 40 2nd nanofiber 42 2nd discharge nozzle 44 2nd nanofiber layer 50 Base material

Claims (5)

Step (A): A step of discharging molten polypropylene from the discharge nozzle, and Step (B): A step of discharging the high-speed high-temperature gas from the gas nozzle to stretch the molten polypropylene to form nanofibers,
A method for producing polypropylene nanofibers comprising:
The manufacturing method whose melt flow rate (230 degreeC, load 21.18N) of the said polypropylene is 300-3000 g / 10min. Step (A): a step of discharging molten polypropylene from the discharge nozzle,
Step (B): A step of forming nanofibers by discharging a high-speed high-temperature gas from a gas nozzle to stretch the molten polypropylene.
Step (C): a step of providing a polypropylene nanofiber layer by adhering the polypropylene nanofibers to a substrate disposed at a position facing the discharge nozzle or the gas nozzle,
A method for producing a laminate comprising:
The manufacturing method whose melt flow rate (230 degreeC, load 21.18N) of the said polypropylene is 300-3000 g / 10min. Step (D): A step of discharging the molten polymer from the second discharge nozzle, discharging a high-speed high-temperature gas from the second gas nozzle, and stretching the molten polymer to form a second nanofiber.
Step (E): a step of attaching a second nanofiber on the polypropylene nanofiber layer formed in the step (C),
The manufacturing method of the laminated body of Claim 2 which further contains these. Step (A ′): a step of discharging a molten polymer other than polypropylene from the discharge nozzle,
Step (B ′): a step of discharging a high-speed high-temperature gas from a gas nozzle and stretching the molten polymer to form nanofibers;
Step (C ′): a step of providing a nanofiber layer by adhering the nanofiber to a substrate disposed at a position facing the discharge nozzle or the gas nozzle,
Step (D ′): a step of discharging the polypropylene according to claim 1 from a second discharge nozzle, discharging a high-speed high-temperature gas from the second gas nozzle, and stretching the polypropylene to form polypropylene nanofibers. ,
Step (E ′): A method for producing a laminate including a step of attaching the polypropylene nanofibers formed in the step (D ′) on the nanofiber layer formed in the step (C ′).   The manufacturing method in any one of Claims 1-4 with which the polypropylene provided to the said nanofiber formation process does not contain an additive.

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