WO2019187827A1 - Nonwoven fabric, method for forming fiber, method for manufacturing nonwoven fabric - Google Patents

Abstract

Provided are a nonwoven fabric having a cushioning feel, a method for forming a fiber, and a method for manufacturing the nonwoven fabric. According to the present invention, nonwoven fabric manufacturing equipment (20) forms a fiber (11) from a solution (25) and manufactures a nonwoven fabric. The nonwoven fabric (10) is formed of a fiber (11). The nonwoven fabric (10) has pores (13) formed therein. The average diameter DF of the fiber 11 is within the range of 0.10 μm to 5.00 μm inclusive. The nonwoven fabric (10) has a porosity of at least 90%. The average pore diameter is within the range of 0.5 μm to 50 μm inclusive, and the standard deviation of the pore diameter is at most 1.5 μm.

Description

Nonwoven fabric, fiber forming method and nonwoven fabric manufacturing method

The present invention relates to a nonwoven fabric, a fiber forming method, and a nonwoven fabric manufacturing method.

Nonwoven fabrics made of fiber are known. Examples of the fiber include a so-called nanofiber having a nano-order diameter of several nm or more and less than 1000 nm, and a so-called micron fiber having a diameter of several micrometers or more and less than 1000 μm.

As a fiber structure including a layer made of fibers such as nonwoven fabric (hereinafter referred to as a fiber layer), for example, in Patent Document 1, it is used as a separator or an insulating material in a battery or the like, and has a high average diameter of 50 nm to 3000 nm. A fiber structure comprising a fiber layer made of molecular fibers is described. This fiber structure has a maximum compression rate of 20% or more at a surface pressure of 5 MPa measured by a predetermined method. The fiber layer has an average pore diameter of 0.01 to 15 μm, a thickness of 0.0025 to 0.3 mm, a porosity of 20 to 90%, a weighing of 1 to 90 g / m ² , and a fragile air permeability of 46 m ³ / min / m. ^{It is} less than ² and the Macmillan number is 2-15.

Incidentally, an electrospinning method is known as a method for producing a fiber such as a nanofiber and a non-woven fabric formed of such a fiber. As described in Patent Document 1, the electrospinning method is also referred to as an electrospinning method or the like, and is performed using, for example, an electrospinning device (also referred to as an electrospinning device) having a nozzle, a collector, and a power source. In a general electrospinning apparatus, a voltage is applied between a nozzle and a collector by a power source, and for example, the nozzle is negatively charged and the collector is positively charged.

When a solution, which is a raw material, is taken out from the nozzle in a state where a voltage is applied, a conical projection composed of a solution called a Taylor cone is formed at the opening at the tip of the nozzle. When the applied voltage is gradually increased and the Coulomb force exceeds the surface tension of the solution, the solution is ejected from the tip of the Taylor cone and a spinning jet is formed. The spinning jet moves to the collector by the Coulomb force and is collected as a fiber on the collector, and a nonwoven fabric composed of the fiber is formed on the collector.

International Publication No. 2014/010753

Nonwoven fabrics made of nanofibers and micronfibers have been actively developed in various fields. Expected uses include, for example, a heat insulating material, a sound absorbing material, a filter, and the like, and are expected to be used as a medical nonwoven fabric.

However, since the fiber structure and the fiber layer described in Patent Document 1 are premised on use in a separator, the porosity of the fiber layer for favorably absorbing the electrolyte, ions flow between the anode and the cathode. The thickness for facilitating the measurement and the weighing for preventing the dendride short between the anode and the cathode are specified. Therefore, for example, the sound absorbing material and the heat insulating material are difficult to develop in the above-mentioned applications such as insufficient sound absorbing performance and heat insulating performance. In this respect, a non-woven fabric having a fluffy feeling, that is, a soft non-woven fabric that wraps a large amount of air, has sound absorption performance, heat insulation performance, and the like, and can be expected to expand its application.

Therefore, an object of the present invention is to provide a nonwoven fabric having a fluffy feeling, a fiber forming method for obtaining the nonwoven fabric, and a nonwoven fabric manufacturing method.

The nonwoven fabric of the present invention comprises a fiber having an average diameter in the range of 0.10 μm to 5.0 μm, a porosity of at least 90%, and an average pore diameter in the range of 0.5 μm to 50 μm, And even if the standard deviation of a hole diameter is large, it is 1.5 micrometers.

The fiber is preferably formed of a cellulosic polymer.

In the fiber forming method of the present invention, a fiber is formed by applying a voltage between a solution in which a fiber material is dissolved in a solvent and the collector, and ejecting the solution from the nozzle to the collector. When the evaporation rate of the solvent is V μl / s and the average diameter of the fiber is DF μm, 1 ≦ V / DF ≦ 10.

It is preferable that the moisture content of the fiber is at least 3.0%.

It is preferable to adjust the moisture content of the fiber by setting the relative humidity of the spinning space between the nozzle and the collector to 10% to 30%. The spinning space is preferably partitioned from the external space by a chamber having a humidity adjusting mechanism for adjusting the internal relative humidity.

The fiber material is preferably a cellulosic polymer. The cellulosic polymer is preferably cellulose acylate. The cellulose acylate is preferably either cellulose acetate propionate or cellulose triacetate.

The solvent is preferably a mixture of a plurality of compounds. The solvent preferably contains dichloromethane and methanol.

The non-woven fabric production method of the present invention collects fibers formed by applying a voltage between a solution in which a fiber material is dissolved in a solvent and a collector and ejecting the solution from a nozzle as a non-woven fabric on the collector. To do. When the evaporation rate of the solvent is V μl / s and the average diameter of the fiber is DF μm, 1 ≦ V / DF ≦ 10.

According to the present invention, a nonwoven fabric with a fluffy feeling can be obtained.

It is a schematic perspective view of a part of the nonwoven fabric which is one Embodiment. It is explanatory drawing of a hole diameter distribution and a standard deviation. It is the schematic of a nonwoven fabric manufacturing equipment. It is the schematic of a nonwoven fabric manufacturing equipment.

The nonwoven fabric 10 of this embodiment shown in FIG. In the nonwoven fabric 10, a plurality of voids 13 as space regions defined by the fibers 11 are formed as portions where air exists. Thus, the nonwoven fabric 10 contains air inside. In FIG. 1, only a part of one surface (hereinafter referred to as a first surface) 10 </ b> A side in the thickness direction Z of the nonwoven fabric 10 is drawn in order to avoid complication of the drawing. Therefore, the nonwoven fabric 10 has a structure in which a large number of fibers 11 are further stacked on the lower side in FIG.

When the plurality of voids 13 communicate with each other in the thickness direction Z of the nonwoven fabric 10, holes that penetrate in the thickness direction Z of the nonwoven fabric 10 are formed. The holes function as filter holes when the nonwoven fabric 10 is used for a filter, for example. In addition, some of the gaps 13 exist as a space region that does not penetrate in the thickness direction Z, for example, is closed by the fiber 11 without forming holes.

The nonwoven fabric 10 only needs to include the fiber 11, and may include other fibers having different materials in addition to the fiber 11. In FIG. 1, the first surface 10 </ b> A is drawn along the XY plane, and Z perpendicular to the XY plane is the thickness direction of the nonwoven fabric 10.

The fiber 11 is formed with a substantially constant diameter D1. The average value of diameter D1 (hereinafter referred to as average diameter) DF (unit: μm) is preferably in the range of 0.10 μm or more and 5.00 μm or less. When the average diameter DF is 0.10 μm or more, detachment of the fiber piece is suppressed as compared with the case where the average diameter DF is less than 0.10 μm. The suppression of the fiber piece detachment means that the fiber piece detachment from the nonwoven fabric 10 is suppressed, and the suppression of the fiber piece detachment leads to excellent durability as the nonwoven fabric 10. . Since the average diameter DF is 5.00 μm or less, the nonwoven fabric 10 has the same volume ratio of air (hereinafter referred to as porosity) compared to the case where the average diameter DF is larger than 5.00 μm. It becomes softer. Further, when the average diameter DF is 5.00 μm or less, the non-woven fabric 10 has a higher porosity even if the nonwoven fabric 10 has the same degree of softness as compared with the case where the average diameter DF is larger than 5.00 μm. When used as a material or a heat insulating material, the sound absorbing performance and the heat insulating performance are increased, and the amount of filtration treatment when used for a filter is increased. The diameter is more preferably in the range of 0.15 μm to 4.00 μm, and still more preferably in the range of 0.20 μm to 3.00 μm.

The average diameter DF can be obtained by measuring the diameter of 100 fibers 11 from an image taken with a scanning electron microscope and calculating the average value.

The nonwoven fabric 10 has a porosity of 90% or more, that is, at least 90%. Thus, the nonwoven fabric 10 with a very high porosity has a fluffy feeling. That is, it contains a large amount of air inside and is soft. Since it contains a large amount of air in this way, it has a wider range of uses than when it has a porosity of less than 90%. For example, since the sound absorption performance and heat insulation performance superior to the case of a porosity of less than 90% are exhibited, it can be used as a sound absorption material and a heat insulation material. Moreover, compared with the case where it is the porosity of less than 90%, when it is set as a filter, a big filtration processing performance is shown. The filtration performance means the treatment amount per unit time and / or the sustainability of a state where clogging is suppressed. In addition, when using for a filter, after bonding the fibers 11 by heating the nonwoven fabric 10, using as a filter may be more preferable. The porosity is preferably 99.8% or less because higher durability as the nonwoven fabric 10 is secured. The porosity is more preferably in the range of 90% or more and 99.8% or less, further preferably in the range of 95% or more and 99.6% or less, and particularly preferably 97% or more and 99.4% or less. Within range.

The porosity (unit:%) is W (unit: g / m ² ), the thickness is H (unit: mm), and the specific gravity of the fiber 11 is ρ1 (unit: kg / m ³ ). Then, [1-{(W / 1000) / (H / 1000)} / ρ1] × 100 can be obtained. For the weighing W, the nonwoven fabric 10 is cut into 5 cm × 5 cm, the mass is measured with an electronic balance (manufactured by METTLER TOLEDO), and a value obtained by converting the measured value per 1 m ² is used. In this example, the thickness H is measured by a non-contact laser displacement meter (LK-H025 manufactured by Keyence Corporation).

The fibers 11 are intertwined, and it is preferable that a portion overlapping in the thickness direction Z and / or a portion contacting in the surface direction (in the XY plane) of the nonwoven fabric 10 is not bonded (not bonded). This is the case in the example. However, there may be a part where the bonding is performed, and even when the bonding is performed, the bonding force is kept small enough to be easily peeled off by a very weak force. As described above, the fibers 11 are intertwined with each other, or even if they are bonded, the adhesive force is suppressed to be small. Therefore, the fibers 11 are soft and deformable in a state of containing a large amount of air. And when used as a sound-absorbing material, the degree of freedom of construction site is large. Further, since the fibers 11 are in an intertwined state, or the adhesive force is kept small even if they are bonded, when the fiber 11 has a small diameter of, for example, 0.10 μm or more and 5.00 μm or less, It can also be torn by applying tension locally. Therefore, it is excellent in workability.

The thickness of the nonwoven fabric 10 is not particularly limited, and can be adjusted according to the amount of fiber 11 deposited as described later, and may be set as appropriate according to the handling situation and / or application. For example, from the viewpoint of handleability (handling) such as workability and durability in handling scenes, it is preferably in the range of 100 μm to 100,000 μm, for example. Further, when used as a sound absorbing material or a heat insulating material, it may be thickened (for example, within a range of 2000 μm or more and 100,000 μm or less) to be applied as it is, or thinned (for example, to be applied in a stacked state) It may be within a range of 200 μm or more and 1000 μm or less. In this example, it is 4000 μm. Although the nonwoven fabric 10 has a large degree of freedom in thickness as described above, it contains a large amount of air and is soft, and therefore has a wide range of uses.

Here, the average pore diameter of the nonwoven fabric 10 in which a plurality of voids 13 are formed is DA (unit: μm). The average pore diameter DA is in the range of 0.5 μm to 50 μm, and the standard deviation of the pore diameter is 1.5 μm or less, that is, 1.5 μm at most. Thus, since the pore diameter is uniform and has a high porosity as described above, for example, when used as a filter, highly accurate filtration is efficiently performed. The average pore diameter DA is more preferably in the range of 2 μm to 30 μm, and still more preferably in the range of 4 μm to 20 μm. The standard deviation of the pore diameter is more preferably 1.0 μm or less, further preferably 0.5 μm or less, and it is more preferable that the pore size is kept small.

The average pore diameter DA can be obtained by the following method. First, a 5 cm square (5 cm × 5 cm) is cut out from the fiber sheet 10 to obtain a sample. After immersing this sample in GALWICK (manufactured by POROUS MATERIAL) having a surface tension of 15.3 mN / m, the average pore diameter DA is determined by measuring by a bubble point method using a palm porometer (manufactured by POROUS MATERIAL). can get.

The standard deviation of the hole diameter is obtained by the following method using the hole diameter distribution (correlation data between the hole diameter and the abundance of holes having the hole diameter) output from the palm porometer. First, in the pore diameter distribution (curve L1 shown by the solid line in FIG. 2 and the corresponding vertical axis is the left vertical axis in FIG. 2) output by the palm porometer, the total amount of holes is 100%. . This is referred to as a total amount of 100%. As indicated by a curve L2 indicated by a broken line in FIG. 3 (the corresponding vertical axis is the right vertical axis in FIG. 2), the abundance of holes is accumulated from the larger hole diameter toward the smaller one, The hole diameter of the holes where the total existing amount is 16% from the larger hole diameter is D (16%), and the hole diameter of the holes whose existing total amount is 84% is D (84%). The standard deviation of the pore diameter is calculated by {D (16%) − D (84%)} / 2.

The fiber 11 is made of resin (polymer). As the polymer, a polymer that can be made into a solution by dissolving in a solvent is used. The polymer is preferably a polymer that can be made into a solution by dissolving in an organic solvent. Examples thereof include polymethyl methacrylate (hereinafter referred to as PMMA), cellulosic polymer, polyester, polyurethane, and elastomer. In this example, for example, a cellulose polymer 15 (see FIG. 3) is used.

The cellulose polymer 15 is preferably cellulose acylate. Cellulose acylate is a cellulose ester in which some or all of the hydrogen atoms constituting the hydroxy group of cellulose are substituted with acyl groups. The cellulose acylate is preferably any one of cellulose acetate propionate (hereinafter referred to as CAP) and cellulose triacetate (hereinafter referred to as TAC).

As described above, according to the above configuration, there is a fluffy feeling and a large amount of air, so that there is excellent heat insulation performance. Therefore, it can be used for, for example, heat insulating building materials for floors, walls, and ceilings, and heat insulating members for vehicles. Furthermore, according to the said structure, heat conductivity is lower than the conventional heat insulating material, and the heat insulation effect is fully exhibited even in a narrow space. Therefore, it can be used as a heat insulating material used inside electronic equipment, in-vehicle equipment, and industrial equipment. Since the fiber diameter is thin, bulky and has excellent sound absorbing performance, it is suitable as a sound absorbing material for homes, vehicles and electrical products. Further, according to the above configuration, sufficient air permeability can be obtained. Therefore, as described in JP-A-2017-82346, sound absorption is achieved by laminating on a porous sound absorbing material (felt, glass wool, urethane foam, etc.). Performance is improved.

According to the above configuration, since the average pore size distribution is narrow, it can be suitably used as a filter for separating or removing a target substance from a mixture of solid and liquid (solid liquid mixture). Among such filters, filters that can be particularly preferably used are for food (including beverages), medical, and ultrapure, where there is concern about contamination (contamination) and high precision separation performance is required. It is a filter for water and high-purity chemicals. Due to the fluffy feeling and the high porosity, it is difficult to clog and the pressure loss is small. Specific examples include a filter for removing fine particles and / or microorganisms from beverages, a pretreatment filter for industrial pure water, and a test filter for collecting specific cells from body fluids such as blood and saliva. . Examples of the test filter include a test filter for blood glucose level test, urine sugar test, lifestyle-related disease test, genetic test, tumor marker test, blood test, and the like.

The nonwoven fabric 10 can be manufactured by, for example, the nonwoven fabric manufacturing facility 20 shown in FIG. The nonwoven fabric manufacturing facility 20 is for forming the fiber 11 and manufacturing the nonwoven fabric 10 using an electrospinning method. The nonwoven fabric manufacturing facility 20 includes a solution preparation unit 21 and a nonwoven fabric manufacturing apparatus 22. The details of the nonwoven fabric manufacturing apparatus 22 are shown in another drawing, and in FIG. 4, only a part of the nonwoven fabric manufacturing apparatus 22 is shown.

The solution preparation unit 21 is for preparing the solution 25 that forms the fiber 11. The solution preparation unit 21 prepares the solution 25 by dissolving the cellulose polymer 15 as a fiber material to be the fiber 11 in the solvent 26. The solution 25 is discharged from each of nozzles 27a to 27c described later, and forms the fiber 11 on the support 28. In the following description, when the nozzle 27a, the nozzle 27b, and the nozzle 27c are not distinguished, they are referred to as a nozzle 27.

When the evaporation rate of the solvent 26 is V (unit: ml / s, milliliter / second), the evaporation rate V and the average diameter DF of the fiber 11 formed on the support 28 are 1 ≦ V / DF ≦ 10 is satisfied. More preferably, 2 ≦ V / DF ≦ 9, and further preferably 3 ≦ V / DF ≦ 8. V / DF is set to the above range by adjusting at least one of the evaporation rate V and the average diameter DF.

The evaporation rate V is obtained by the following equation (1). C is the concentration of the solution 25 (unit:%). The concentration C is obtained by a calculation formula of {M1 / (M1 + M2)} × 100, where the mass of the fiber material is M1 and the mass of the solvent is M2. In this example, M1 is the mass of the cellulosic polymer 15, and M2 is the mass of the solvent 26. Q is the discharge amount of the solution 25 from the nozzle 27 (the volume discharged per hour, the unit is ml / h, milliliter / hour). ρ2 is the density of the solution 25 (unit: g / ml). Therefore, the evaporation rate V can be adjusted by increasing or decreasing at least one of the density C, the discharge amount Q, and the density ρ2. The evaporation rate V can also be adjusted by adjusting the formulation of the solvent 26 (for example, the component ratio when the solvent 26 is a mixture of a plurality of components). The average diameter DF can be adjusted by increasing or decreasing at least one of the ejection amount Q, the concentration C, the applied voltage described later, and the distance L from the nozzle 27 to the support 28. In this example, the temperature of the spinning space, which is the space between the nozzle 27 and the support 28, is approximately 25 ° C., and therefore the evaporation rate V is obtained at 25 ° C., approximately the same as the temperature of the spinning space. Yes.
V = {(1-0.01C) × Q × 10 ⁻³ } / (3600 × ρ2) (1)

The solvent 26 may be composed of one kind of compound or may be composed of two or more kinds of compounds. However, since the solvent 26 has a function of adjusting the evaporation rate V in addition to the viewpoint of dissolving the fiber material, the solvent 26 is a mixture composed of two or more kinds of compounds from the viewpoint of adjusting the evaporation rate V. preferable. The solvent 26 of this example is also a mixture and contains a plurality of compounds. For example, dichloromethane is used as the first compound 26a, and methanol is used as the second compound 26b. In addition to the first compound 26a and the second compound 26b, other compounds different from the first compound 26a and the second compound 26b are used as the third compound, the fourth compound,. The solvent 26 may be configured as follows.

Solvent 26 preferably has a boiling point of 90 ° C. or lower. In addition, when the solvent 26 is a mixture of a plurality of compounds, the boiling point of the compound having the largest mass ratio is regarded as the boiling point of the solvent 26. In addition, when the solvent 26 is a mixture of three or more types of compounds and there are a plurality of compounds having the largest mass ratio, the boiling point of the compound having the highest boiling point is regarded as the boiling point of the solvent 26. For example, the solvent 26 is a mixture of the compound a, the compound b, and the compound c, and (mass of the compound a) :( mass of the compound b) :( mass of the compound c) = 40: 40: 20 When the compound having the largest ratio is the compound a and the compound b, the boiling point of the compound a and the compound b having the higher boiling point is regarded as the boiling point of the solvent 26. The solvent 26 is preferably an organic compound, that is, an organic solvent.

When cellulose acylate is used as the cellulose polymer 15, the solvent 26 is methanol, ethanol, isopropanol, butanol, benzyl alcohol, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl formate, Ethyl formate, hexane, cyclohexane, dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, xylene, dimethylformamide, N-methylpyrrolidone, diethyl ether, dioxane, tetrahydrofuran, 1-methoxy-2-propanol and the like can be used. These may be used singly or in combination of two or more.

Further, when PMMA is used as the fiber material, methanol, dichloromethane, chloroform, toluene, acetone, tetrahydrofuran, or the like can be used as the solvent 26. These may also be used alone or in combination of two or more.

The moisture content of the fiber 11 on the support 28 is preferably 3.0% or more, that is, at least 3.0%. The water content is more preferably in the range of 3.0% to 10.0%, and preferably in the range of 4.0% to 9.0%, and preferably 5.0% to 8.%. More preferably, it is in the range of 0% or less.

In this example, the nonwoven fabric manufacturing facility 20 includes pipes 33a to 33c that connect the solution preparation unit 21 and the nonwoven fabric manufacturing apparatus 22, and the nonwoven fabric manufacturing apparatus 22 has nozzles 27a to 27c arranged in a state of being separated from each other. . The pipes 33a to 33c are for guiding the solution 25. The pipe 33a connects the solution preparation unit 21 and the nozzle 27a, the pipe 33b connects the solution preparation unit 21 and the nozzle 27b, and the pipe 33c connects the solution preparation unit 21 and the nozzle 27c. Thereby, the solution 25 is discharged from each of the nozzles 27a to 27c. The solutions 25 exiting from the nozzles 27a to 27c form the fibers 11, respectively. In the following description, when the pipe 33a, the pipe 33b, and the pipe 33c are not distinguished, they are described as the pipe 33.

In this example, a long support 28 is used to collect and deposit the fibers 11 (hereinafter collectively referred to as accumulation) and to support the nonwoven fabric 10, and the support 28 is moved in the longitudinal direction. ing. Although details of the support 28 will be described later with reference to another drawing, the horizontal direction in FIG. 3 is the width direction of the support 28, and the depth direction in FIG. 3 is the moving direction of the support 28. The nozzles 27a to 27c are arranged in this order in the width direction of the support 28. In this example, the number of nozzles 27 is three, but the number of nozzles 27 is not limited to this. Each of the pipes 33a to 33c is provided with a pump 38 for sending the solution 25 to the nozzle 27. By changing the number of rotations of the pump 38, each discharge amount of the solution 25 discharged from the nozzles 27a to 27c is adjusted.

The nozzles 27a to 27c are held by a holding member 41. The holding member 41 and the nozzle 27 constitute a nozzle unit 42 of the nonwoven fabric manufacturing apparatus 22.

The nonwoven fabric manufacturing apparatus 22 will be described with reference to FIG. FIG. 4 shows a case when viewed from the nozzle 27 a side of FIG. 3, and for the nozzle 27, only the nozzle 27 a is illustrated. The nonwoven fabric manufacturing apparatus 22 includes a chamber 45, the above-described nozzle unit 42, a stacking unit 50, a power source 51, and the like.

The chamber 45 accommodates, for example, the nozzle unit 42 and a part of the stacking unit 50. The chamber 45 is configured to be hermetically sealed, thereby preventing the solvent gas from leaking to the outside. The solvent gas is obtained by vaporizing the solvent 26 of the solution 25.

The chamber 45 includes a humidity adjusting mechanism 45a that adjusts the internal relative humidity (hereinafter simply referred to as humidity). The humidity adjusting mechanism 45 a sends a gas (for example, air) whose humidity has been adjusted to the chamber 45, collects the atmosphere in the chamber 45, adjusts the humidity again, and sends it to the chamber 45. In this way, the humidity inside the chamber 45 is adjusted. This humidity adjustment is performed to adjust the humidity of the spinning space described above. That is, the chamber 45 has a function of partitioning the spinning space from the external space and adjusting the humidity of the spinning space. However, the adjustment of the humidity of the spinning space is not limited to the method of this example using the chamber 45. For example, the humidity of the spinning space may be adjusted by a chamber that defines the spinning space in the chamber 45.

The spinning space humidity is preferably 10% or more and 30% or less. The humidity may change during the formation of the fiber 11 and the production of the nonwoven fabric 10 as long as it is within this range. The humidity of the spinning space is more preferably in the range of 15% to 25%.

The nozzle unit 42 is disposed in the upper part of the chamber 45. The tip from which the solution 25 of the nozzle 27 exits is directed to the collector 52 disposed below the nozzle 27 in FIG. When the solution 25 exits from an opening formed in the tip of the nozzle 27 (hereinafter referred to as a tip opening), a generally conical Taylor cone 53 is formed by the solution 25 in the tip opening.

The stacking unit 50 is disposed below the nozzle 27. The stacking unit 50 includes a collector 52, a collector rotating unit 56, a support supply unit 57, and a support winding unit 58. The collector 52 attracts the solution 25 from the nozzle 27 and collects the formed fiber 11 as the nonwoven fabric 10, and in this embodiment, collects it on a support 28 described later.

The collector 52 is composed of an endless belt formed in a ring shape with a metal strip. The collector 52 may be made of a material that is charged when a voltage is applied by the power supply 51, and is made of, for example, stainless steel. The collector rotating unit 56 includes a pair of rollers 61 and 62, a motor 60, and the like. The collector 52 is stretched horizontally around the pair of rollers 61 and 62. A motor 60 disposed outside the chamber 45 is connected to the shaft of one roller 61 and rotates the roller 61 at a predetermined speed. This rotation causes the collector 52 to move and circulate between the rollers 61 and 62. In the present embodiment, the moving speed of the collector 52 is, for example, 0.2 m / min, but is not limited thereto.

The collector 52 is supplied with a support 28 made of, for example, an aluminum sheet by a support supply unit 57. The support 28 is for collecting the fibers 11 and obtaining the nonwoven fabric 10. The support body supply unit 57 has a delivery shaft 57a. A support roll 63 is attached to the delivery shaft 57a. The support roll 63 is configured by winding the support 28 around a winding core 64. The support winding unit 58 has a winding shaft 67. The winding shaft 67 is rotated by a motor (not shown), and the support body 28 on which the nonwoven fabric 10 is formed is wound around the core 68 to be set. Thus, this nonwoven fabric manufacturing apparatus 22 has a function of forming the fiber 11 and a function of forming the nonwoven fabric 10. The support 28 may be placed on the collector 52 and moved by moving the collector 52.

The nonwoven fabric 10 may be formed by directly collecting the fibers 11 on the collector 52. However, depending on the material forming the collector 52 or the surface state of the collector 52, the nonwoven fabric 10 is stuck and is difficult to peel off. There is a case. For this reason, it is preferable to guide the support body 28 on which the nonwoven fabric 10 is difficult to adhere to the collector 52 as in this embodiment, and to integrate the fiber 11 on the support body 28.

The power supply 51 applies a voltage to the nozzle 27 and the collector 52, thereby charging the nozzle 27 to the first polarity and charging the collector 52 to the second polarity opposite to the first polarity. Part. By passing through the charged nozzle 27, the solution 25 is charged and exits the nozzle 27 in a charged state. In this example, the holding member 41 and the nozzle 27 are electrically connected, and the voltage is applied to the nozzle 27 via the holding member 41 by connecting the power source 51 to the holding member 41. The method of applying the voltage is not limited to this. For example, a voltage may be applied to each nozzle 27 by connecting a power source 51 to each nozzle 27. In this embodiment, the nozzle 27 is charged positively (+) and the collector 52 is negatively charged (−). However, the polarity of the nozzle 27 and the collector 52 may be reversed. The collector 52 side may be grounded and the potential may be set to zero. Due to the charging, the solution 25 is ejected from the Taylor cone 53 toward the collector 52 as a spinning jet 69. In this example, the solution 25 is charged by applying a voltage to the nozzle 27, but the solution 25 may be charged in the pipe 33 and the charged solution 2 may be guided to the nozzle 27.

The distance L between the nozzle 27 and the collector 52 varies depending on the type of the cellulosic polymer 15 and the solvent 26, the mass ratio of the solvent 26 in the solution 25, and the like, but is preferably in the range of 30 mm or more and 500 mm or less. For example, it is 150 mm.

The voltage (applied voltage) applied to the nozzle 27 and the collector 52 is preferably 5 kV or more and 200 kV or less. From the viewpoint of forming the fiber 11 thinner, the applied voltage is preferably as high as possible within this range. In this embodiment, it is 40 kV, for example.

The operation of the nonwoven fabric manufacturing facility 20 will be described. A voltage is applied by the power source 51 to the nozzle 27 and the collector 52 that circulates and moves. As a result, the nozzle 27 is positively charged as the first polarity, and the collector 52 is negatively charged as the second polarity. The solution 25 is continuously supplied from the solution preparation unit 21 to the nozzle 27, and the support 28 is continuously supplied onto the moving collector 52. The solution 25 is charged positively as the first polarity by passing through each of the nozzles 27a to 27c, and exits from the tip openings of the nozzles 27a to 27c in a charged state.

The collector 52 attracts the solution 25 that has exited from the tip opening while being charged to the first polarity. As a result, a Taylor cone 53 is formed at the tip opening, and the spinning jet 69 exits from the Taylor cone 53 toward the collector 52. The spinning jet 69 charged to the first polarity splits into a smaller diameter due to repulsion due to its own charge and / or extends to a smaller diameter while drawing a spiral trajectory while heading toward the collector 52. The fiber 11 is collected on the support 28. Since the fiber 11 is deposited in a very short time, it is collected as the nonwoven fabric 10. In addition, the thickness of the nonwoven fabric 10 can be adjusted by increasing / decreasing the deposition amount. For example, the amount of deposition can be increased or decreased by adjusting the moving speed of the support 28.

Since 1 ≦ V / DF ≦ 10, the fiber 11 having an average diameter DF of 0.10 μm or more and 5.00 μm or less is formed, the porosity is 90% or more, and the average pore diameter DA is 0.5 μm or more. The non-woven fabric 10 having a pore diameter standard deviation of 1.5 μm or less is obtained within a range of 50 μm or less. Specifically, by satisfying 1 ≦ V / DF, the spinning jet 69 becomes thinner than in the case of V / DF <1, so that the solvent 26 is sufficiently evaporated and the average diameter DF is within the above range. It becomes the fiber 11 and reaches the support 28. As a result, the fibers 11 are deposited on the support 28 in a non-adhered state with each other or in a state in which the adhesive force is extremely small even when bonded. As a result, the nonwoven fabric 10 has a porosity of 90% or more, an average pore diameter DA in the range of 0.5 μm to 50 μm, and a standard deviation of the pore diameter of 1.5 μm or less. By satisfying V / DF ≦ 10, the spinning jet 69 reliably forms the fiber 11 and does not become beads (microspheres) as compared with the case of 10 <V / DF. Since the beads are not formed, the beads do not fill the gap 13 of the nonwoven fabric 10 on the support 28. As a result, the porosity is surely 90% or more.

Since the spinning space is adjusted to a humidity of 10% or more and 30% or less, the moisture content of the fiber 11 on the support 28 is surely 3.0% or more, and does not exceed 10%. Since the moisture content of the fiber 11 on the support 28 is 3.0% or more, the spinning jet 69 generated thereafter is more reliably formed as the fiber 28 as compared with the case where it is less than 3.0%. Accumulate and deposit on top. This serves as an earth function for releasing electric charges due to moisture contained in the fiber 11 collected on the support 37, and therefore, the spinning jet 69 generated in the spinning space is suppressed from scattering to the periphery. In this state, it is considered that the fiber 11 is reached toward the support 28. In addition, when the moisture content of the fiber 11 is 3.0% or more, coupled with 1 ≦ V / FD ≦ 10, the nonwoven fabric 10 is more reliably manufactured with a porosity of 90% or more. When the moisture content is 10% or less, compared to the case where the moisture content is larger than 10%, the fiber 11 that has absorbed moisture is prevented from being deformed by its own weight, and the gap is easily maintained high.

By using the solvent 26 having a boiling point of 90 ° C. or lower, the solvent 26 is more easily evaporated from the spinning jet 69 and excessive evaporation is suppressed as compared with the case where the solvent 26 having a boiling point higher than 90 ° C. is used. The Further, by using an organic solvent as the solvent 26, the spinning jet 69 evaporates an appropriate amount of the solvent 26 while passing through the spinning space in which the humidity is adjusted, as compared with the case where water is used, for example. And keep the balance of spinning space and moisture. As a result, it is easy to balance the degree of drying of the fiber 11 and the moisture content.

The fiber 11 forms the fluffy nonwoven fabric 10 and is sent to the support winding portion 58 together with the support 28. The nonwoven fabric 10 is wound around the core 68 in a state where it overlaps the support 28. After the winding core 68 is removed from the winding shaft 67, the nonwoven fabric 10 is separated from the support 28. The nonwoven fabric 10 thus obtained is long, but after that, for example, it may be cut into a desired size.

In this example, a circulating belt is used as the collector 52, but the collector is not limited to a belt. For example, the collector may be a fixed flat plate or a cylindrical rotating body. Also in the case of a collector made of a flat plate or a cylindrical body, it is preferable to use the support 28 so that the nonwoven fabric 10 can be easily separated from the collector. When a rotating body is used, a cylindrical sheet material made of fibers is formed on the peripheral surface of the rotating body. Therefore, after spinning, the cylindrical sheet material is extracted from the rotating body, and is formed into a desired size and shape. Cut it out.

In the above example, the nozzle 27 is disposed with the tip opening facing downward, and the collector 52 is disposed under the nozzle 27, whereby the solution 25 is discharged downward. However, the discharge direction of the solution 25 is not limited to this example. For example, the solution 25 may be discharged upward by disposing the nozzle 27 with the tip opening facing upward and disposing the collector 52 on the nozzle 27.

[Example 1] to [Example 8]
Using the nonwoven fabric manufacturing facility 20, the nonwoven fabric 10 was manufactured under the conditions shown in Table 1, and Examples 1 to 8 were obtained. The thickness of the manufactured nonwoven fabric 10 is 4000 micrometers as above-mentioned. The fiber material used is described in the “fiber material” column of Table 1.

The solvent 26 was a mixture of the first compound 26a and the second compound 26b. The first compound 26a and the second compound 26b used are shown in Table 1. In Table 1, “DMC” is dichloromethane, “MeOH” is methanol, and “NMP” is N-methylpyrrolidone. The "mass ratio of the first compound and the second compound" column in Table 1 indicates (mass of the first compound) :( mass of the second compound). For example, "87:13" It means that the mass of the first compound) :( the mass of the second compound) = 87: 13. “Moisture content” in Table 1 is the moisture content of the fiber 11 integrated on the support 28. In the column “Standard deviation of pore diameter” in Table 1, when the result of rounding off the value obtained with two decimal places is 0.0, “<0.1” is entered.

The fluffiness, which is the elasticity when the obtained nonwoven fabric 10 is repeatedly pressed with two fingers, corresponds to the following compression rate evaluation. Specifically, the compression ratio was higher as more fluffy feeling was felt. Therefore, the compression ratio was evaluated as an evaluation of fluffiness.

The compression rate was evaluated by the following method. First, a size of 10 cm × 10 cm was cut out from the nonwoven fabric 10 as a sample. The sample was allowed to stand with the first surface 10A facing upward, a weight of 800 g was placed on the first surface 10A, and the thickness of the loaded sample was measured with calipers. In any sample, when the weight was removed, the first surface 10A returned to the original height, and the shape was restored. The compression ratio was obtained by dividing the thickness before loading the weight (4000 μm) by the thickness of the loaded state. The compression ratio is shown in Table 1.

Furthermore, genetic testing was performed using the nonwoven fabric 10 obtained in Example 1. Specifically, after filtering human whole blood with the nonwoven fabric 10 obtained in Example 1, white blood cells remaining on the nonwoven fabric 10 are used, and paragraphs [0057] to [0061] in the specification of Japanese Patent No. 4058508 are disclosed. Genetic testing was performed according to the method described in. As a result, the same result as the example described in Japanese Patent No. 4058508 was obtained.

[Comparative Example 1] to [Comparative Example 2]
Nonwoven fabrics were produced under the conditions shown in Table 1 and designated as Comparative Examples 1 and 2.

The compression ratio was evaluated as fluffy by the same method and standard as in the examples. The evaluation results are shown in Table 1.

DESCRIPTION OF SYMBOLS 10 Nonwoven fabric 10A 1st surface 11 Fiber 13 Space | gap 15 Cellulosic polymer 20 Nonwoven fabric manufacturing equipment 21 Solution preparation part 22 Nonwoven fabric manufacturing apparatus 25 Solution 26 Solvent 26a 1st compound 26b 2nd compound 27a-27c Nozzle 28 Support body 33a-33c Piping 38 Pump 41 Holding member 42 Nozzle unit 45 Chamber 45a Humidity adjustment mechanism 50 Accumulation part 51 Power supply 52 Collector 53 Taylor cone 56 Collector rotation part 57 Support body supply part 57a Delivery shaft 58 Support body winding part 60 Motor 61, 62 Roller 63 Support body Roll 64 Winding core 67 Winding shaft 68 Winding core 69 Spinning jet D1 Diameter L Distance

Claims (12)

Provided with a fiber having an average diameter in the range of 0.10 μm to 5.00 μm, a porosity of at least 90%, an average pore diameter in the range of 0.5 μm to 50 μm, and a standard deviation of the pore diameter A non-woven fabric that is 1.5 μm at most. The nonwoven fabric according to claim 1, wherein the fiber is formed of a cellulose-based polymer. In a fiber forming method of forming a fiber by applying a voltage between a solution in which a fiber material is dissolved in a solvent and a collector, and ejecting the solution from the nozzle to the collector,
A fiber forming method in which 1 ≦ V / DF ≦ 10 when the evaporation rate of the solvent is V μl / s and the average diameter of the fiber is DF μm. The fiber forming method according to claim 3, wherein a moisture content of the fiber is set to at least 3.0%. The fiber forming method according to claim 3 or 4, wherein the moisture content of the fiber is adjusted by adjusting a relative humidity of a spinning space between the nozzle and the collector to 10% or more and 30% or less. The fiber forming method according to claim 5, wherein the spinning space is partitioned from the external space by a chamber having a humidity adjusting mechanism for adjusting an internal relative humidity. The fiber forming method according to any one of claims 3 to 6, wherein the fiber material is a cellulosic polymer. The fiber forming method according to claim 7, wherein the cellulose polymer is cellulose acylate. The fiber forming method according to claim 8, wherein the cellulose acylate is either cellulose acetate propionate or cellulose triacetate. The fiber forming method according to any one of claims 3 to 9, wherein the solvent is a mixture of a plurality of compounds. The fiber forming method according to claim 10, wherein the solvent contains dichloromethane and methanol. A voltage is applied between the solution in which the fiber material is dissolved in the solvent and the collector, and the fiber formed by ejecting the solution from the nozzle is collected as a nonwoven fabric on the collector,
A non-woven fabric manufacturing method wherein 1 ≦ V / DF ≦ 10, where the evaporation rate of the solvent is V μl / s and the average diameter of the fiber is DF μm.

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