JP2018059225A - Method for manufacturing fiber structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a manufacturing step of a fiber structure that is made to carry an adsorbent to improve productivity.SOLUTION: The method for manufacturing a fiber structure includes: a preparation step of preparing a mixture liquid comprising a raw material resin for a fiber, an adsorbent, and a liquid substance that dissolves the raw material resin and dissolves or disperses the adsorbent and a first porous sheet; a first lamination step of jetting the mixture liquid to generate the fiber and accumulating it on one surface of the first porous sheet to form a fiber layer; and a second lamination step of laminating a second porous sheet on the fiber layer. In the first lamination step, the fiber is made to carry the adsorbent that is particulate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a fiber structure, and more particularly to a method for manufacturing a fiber structure carrying an adsorbent.

  In recent years, filter media used in air cleaners and the like are required to have a function of adsorbing chemical substances in the air in addition to dust collection. In particular, formaldehyde is regarded as a causative substance of sick house syndrome and has become a social problem. Therefore, Patent Documents 1 and 2 disclose a fiber structure in which an adsorbent that adsorbs a chemical substance is dispersed between a base material layer and a surface layer.

JP 2002-248309 A JP 2009-190269 A

  In Patent Documents 1 and 2, the adsorbent is mixed with the hot melt adhesive and then sprayed on the base material layer. In this case, the adsorbent is supported on the base material layer by further performing heat treatment to melt the hot melt adhesive. In this method, in order to carry the adsorbent, the adsorbent spraying step and the adhesive heating step are required as separate steps. As a result, productivity tends to decrease.

  One aspect of the present invention is a mixed liquid containing a fiber raw resin, an adsorbent, and a liquid material that dissolves the raw resin and dissolves or disperses the adsorbent, and a first porous sheet A first step of forming the fiber layer by spraying the mixed solution to form the fiber and depositing the fiber on one surface of the first porous sheet; and the fiber. And a second lamination step of laminating a second porous sheet on the layer, and in the first lamination step, the fibrous adsorbent is supported on the fibers.

  According to the present invention, since the adsorbent is carried on the fiber together with the generation of the fiber, the manufacturing process of the fiber structure is simplified and the productivity is improved.

It is a figure which shows the structural example of the manufacturing system used for manufacture of the fiber structure which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the fiber structure manufactured by the manufacturing method which concerns on one Embodiment of this invention. It is a top view which shows typically the fiber which comprises a fiber layer, and the adsorption agent carry | supported by this.

  The manufacturing method of the fiber structure according to the present embodiment includes a raw material resin of fiber (hereinafter referred to as first fiber), an adsorbent, a liquid material that dissolves the raw resin and dissolves or disperses the adsorbent. And a preparation step for preparing a first porous sheet, and a mixture liquid is jetted to generate first fibers and deposited on one surface of the first porous sheet, A first laminating step of forming a fiber layer; and a second laminating step of laminating a second porous sheet on the fiber layer.

  In the first lamination step, an electrospinning method is preferably used. In the electrospinning method, a target is grounded or charged negatively (or positively), and a mixed liquid to which a positive (or negatively) potential is applied is ejected from a nozzle. In the process of reaching the target, the solvent of the liquid mixture is volatilized, and the fibrous material of the raw material generated by the electrostatic stretching phenomenon is deposited on the target to form a non-woven fiber layer.

  Here, the mixed liquid used in the present embodiment includes the first fiber raw material resin, the adsorbent, and the liquid material. Therefore, when at least a part of the liquid is removed by spraying the mixed liquid, particulate adsorbent is generated (or separated) together with the first fibers from the mixed liquid. In the same space, particulate adsorbent (hereinafter referred to as adsorbent particles) and first fibers are formed, and both come into contact with each other and adhere as they are. That is, the generated or separated adsorbent particles are supported on the first fibers generated in the same space. Thereafter, the first fibers carrying the adsorbent particles are deposited on the first porous sheet to form a fiber layer.

  As described above, in the first lamination step, the fiber layer is formed by the generation and deposition of the first fibers, and the adsorbent particles are supported on the first fibers. In other words, in the first laminating step, generation of the first fibers, support of the adsorbent particles by the first fibers, and formation of a fiber layer including the adsorbent and the first fibers are performed. Therefore, the manufacturing process is simplified and the productivity is improved. The carrying of the adsorbent by the first fibers performed in the first lamination step means that the adsorbent is not only in contact with the first fibers but also that at least a part of the adsorbent is adhered to the first fibers. In the bonding, as described later, the mode in which the surface of the adsorbent and the surface of the first fiber are bonded at points (point bonding), the mode in which the surface of the adsorbent is wound by the first fibers, and the adsorbent A mode in which is penetrated by the first fiber can be included.

  Hereinafter, the manufacturing method of the present embodiment and the manufacturing system for performing the same will be specifically described with reference to the drawings, taking the case of using the electrospinning method as an example, but the following manufacturing system limits the present invention. Not what you want. FIG. 1 is a diagram schematically showing a configuration of an example of a manufacturing system 200 for the fiber structure 10. The manufacturing system 200 constitutes a manufacturing line for manufacturing the fiber structure 10.

  The fiber structure 10 can be manufactured by an in-line method in which facilities are arranged in the order of processes as in the manufacturing system 200, for example. The manufacturing system 200 conveys the first porous sheet 2 from the upstream to the downstream of the line, and after forming the fiber layer 1 (see FIG. 2) on the main surface of the first porous sheet 2 to be conveyed, This is a manufacturing system for laminating two porous sheets 3.

  The manufacturing system 200 includes: (1) a first porous sheet supply unit 201 that supplies the first porous sheet 2 to the transport belt; and (2) the first fibers 1F and the adsorbent particles 4 from the mixed solution by electrostatic force. And an electrospinning unit 202 having an electrospinning mechanism for depositing on the first porous sheet 2 being conveyed, and (3) a composite of the first porous sheet 2 and the fiber layer 1 fed from the electrospinning unit 202 A second porous sheet laminating unit 203 for laminating the second porous sheet 3 from the fiber layer 1 side of the body.

(Preparation process)
1stly, the liquid mixture 22 containing raw material resin of 1st fiber 1F and adsorbent is prepared. In the mixed liquid 22, the adsorbent may be dispersed as particles, may be dissolved in a solvent contained in the mixed liquid 22, or may be partly dispersed and the remaining part dissolved. It is preferable that at least a part of the adsorbent is contained in the mixed solution 22 in a state where the adsorbent particles 4 are easily supported on the first fibers 1F. On the other hand, since the concentration of the adsorbent in the mixed liquid 22 can be increased to increase the amount of adsorbent particles 4, the adsorbent may be contained in a dispersed state in the mixed liquid 22.

  The method for preparing the mixed liquid 22 containing the adsorbent is not particularly limited. For example, the mixed liquid 22 may be dissolved and / or dispersed by mixing an adsorbent in a powder state in a polymer solution in which the raw material resin of the first fiber 1F is dissolved in a solvent (first solvent). Alternatively, the polymer solution may be prepared by mixing an adsorbent solution in which the adsorbent is dissolved in a solvent (second solvent) and / or an adsorbent dispersion in which the adsorbent is dispersed in a dispersion medium. Among these, it is preferable to mix the adsorbent solution and / or the adsorbent dispersion and the polymer solution in that the polymer solution and the adsorbent are easily mixed uniformly.

  The density | concentration of the raw material resin of the 1st fiber 1F in the liquid mixture 22 is not specifically limited. The density | concentration of raw material resin is 5-30 mass%, for example, and it is preferable that it is 10-20 mass%. The concentration of the adsorbent in the mixed liquid 22 is preferably 5 to 50% by mass and more preferably 10 to 20% by mass from the viewpoint of adsorption performance.

  The raw material resin of the first fiber 1F is not particularly limited. For example, polyamide (PA), polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polyacetal (POM), polycarbonate (PC), polyether Ether ketone (PEEK), polysulfone (PSF), polyether sulfone (PES), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyarylate (PAR), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF) ), Polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), polypropylene (PP), polyester (for example, polyethylene terephthalate (PET), polybutylene terephthalate), polyurethane (PU), etc. Ma and the like. You may use these individually or in combination of 2 or more types. Among these, PES is preferably used because it is suitable for the electrospinning method. Moreover, PVDF is preferably used in that the average fiber diameter D1 can be easily reduced.

  Although it does not specifically limit as an adsorbent, For example, the substance which can adsorb | suck at least 1 sort (s) of volatile organic compounds (VOC), such as formaldehyde, acetaldehyde, toluene, xylene, ethyl acetate, is mentioned. Specific examples of the adsorbent include organic materials that can be dissolved or dispersed in a first solvent or a second solvent such as adipic acid dihydrazide, and particulate materials that are dispersed in a dispersion medium such as activated carbon or zeolite. .

  What is necessary is just to select an appropriate thing as a 1st solvent according to the kind and manufacturing conditions of raw material resin. For example, methanol, ethanol, 1-propanol, 2-propanol, hexafluoroisopropanol, tetraethylene glycol, triethylene glycol, dibenzyl alcohol, 1,3-dioxolane, 1,4-dioxane, methyl ethyl ketone, methyl isobutyl ketone, methyl- n-hexyl ketone, methyl-n-propyl ketone, diisopropyl ketone, diisobutyl ketone, acetone, hexafluoroacetone, phenol, formic acid, methyl formate, ethyl formate, propyl formate, methyl benzoate, ethyl benzoate, propyl benzoate, acetic acid Methyl, ethyl acetate, propyl acetate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, methyl chloride, ethyl chloride, methylene chloride, chloroform, o-chlorotoluene, p- Lorotoluene, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, trichloroethane, dichloropropane, dibromoethane, dibromopropane, methyl bromide, ethyl bromide, propyl bromide, acetic acid, benzene, toluene, hexane, cyclohexane , Cyclohexanone, cyclopentane, o-xylene, p-xylene, m-xylene, acetonitrile, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide (DMAc), dimethyl sulfoxide, pyridine, water, etc. it can. These may be used alone or in combination of two or more. Among these, DMAc is preferable because it is suitable for the electrospinning method and when the first fiber 1F containing PES is formed by the electrospinning method, PES is easily dissolved.

  The second solvent and the dispersion medium are not particularly limited, and may be selected appropriately depending on the type and concentration of the adsorbent. What is necessary is just to select suitably from the solvent used for the polymer solution illustrated above as a 2nd solvent and a dispersion medium. The first solvent and the second solvent or dispersion medium may be the same or different. Among these, the first solvent and the second solvent or the dispersion medium are preferably compatible with each other and more preferably contain the same liquid material from the viewpoint of obtaining a uniform mixed liquid 22.

  Second, the first porous sheet 2 is prepared. The first porous sheet 2 may be a target for depositing the first fibers 1F in the first lamination step and a base material that maintains the shape of the fiber structure 10. The material of the first porous sheet 2 will be described later. In the manufacturing system 200, the 1st porous sheet 2 is conveyed downstream from the upstream of a manufacturing line. The most upstream of the manufacturing system 200 is provided with a first porous sheet supply unit 201 that houses therein a first porous sheet 2 wound in a roller shape. The first porous sheet supply unit 201 rotates the first supply reel 12 by the motor 13 and supplies the first porous sheet 2 wound around the first supply reel 12 to the transport roller 11.

(First lamination step)
The first porous sheet 2 is conveyed to the electrospinning unit 202 by the conveying roller 11. The electrospinning mechanism provided in the electrospinning unit 202 includes an emitter 23 for discharging the mixed liquid 22 of the first fibers 1F installed above the unit, and charging for positively charging the discharged mixed liquid 22. Means (see below) and a transport conveyor 21 for transporting the first porous sheet 2 disposed so as to face the discharge body 23 from the upstream side to the downstream side. The conveyor 21 functions as a collector unit that collects the first fibers 1F together with the first porous sheet 2. Note that the number of electrospinning units 202 is not particularly limited, and may be one or two or more.

  When there are a plurality of electrospinning units 202 and / or emitters 23, the average fiber diameter D1 of the first fibers 1F formed may be changed for each electrospinning unit 202 or for each emitter 23. The average fiber diameter D1 of the first fibers 1F adjusts the discharge pressure of the mixed liquid 22, the applied voltage, the concentration of the raw material resin in the mixed liquid 22, the distance between the emitter 23 and the first porous sheet 2, temperature, humidity, and the like. This can be changed.

  A plurality of discharge ports (not shown) for the mixed liquid 22 are provided on the side of the emitter 23 facing the main surface of the first porous sheet 2. The distance between the discharge port of the emitter 23 and the first porous sheet 2 depends on the scale of the electrospinning unit 202 and the desired fiber diameter, but may be, for example, 100 to 600 mm. The emitter 23 is disposed above the electrospinning unit 202, and the second support 25 extending downward from the first support 24 parallel to the transport direction of the first porous sheet 2 causes the longitudinal direction of the emitter 23 to be first. 1 It is supported so as to be parallel to the main surface of the porous sheet 2. The first support 24 may be movable so that the emitter 23 is swung in a direction perpendicular to the conveyance direction of the first porous sheet 2.

  The charging means includes a voltage applying device 26 that applies a voltage to the emitter 23 and a counter electrode 27 that is installed in parallel with the transport conveyor 21. The counter electrode 27 is grounded. Thereby, a potential difference (for example, 20 to 200 kV) according to the voltage applied by the voltage application device 26 can be provided between the emitter 23 and the counter electrode 27. The configuration of the charging unit is not particularly limited. For example, the counter electrode 27 may be negatively charged. Moreover, you may comprise the belt part of the conveyance conveyor 21 from a conductor instead of providing the counter electrode 27. FIG.

  The emitter 23 is made of a conductor, has a long shape, and is hollow inside. The hollow portion serves as a storage portion that stores the mixed liquid 22. The liquid mixture 22 is supplied from the liquid mixture tank 29 to the hollow of the emitter 23 by the pressure of the pump 28 communicating with the hollow portion of the emitter 23. The mixed liquid 22 is discharged from the discharge port toward the main surface of the first porous sheet 2 by the pressure of the pump 28.

  The discharged mixed liquid 22 causes electrostatic explosion while moving in the space (generation space) between the emitter 23 and the first porous sheet 2 in a charged state, and the raw material resin is formed into a fiber shape. On the other hand, the adsorbent dissolved in the liquid is formed into particles. This is because the adsorbent has lower spinnability than the raw material resin. The adsorbent dispersed in the liquid is separated. Thus, the adsorbent particle 4 produced | generated or isolate | separated within the same production | generation space and the 1st fiber 1F contact, and the adsorbent particle 4 is carry | supported by the 1st fiber 1F. The first fibers 1F carrying the adsorbent particles 4 are deposited on the first porous sheet 2 to form the fiber layer 1. The fiber layer 1 and the first porous sheet 2 can be joined without using an adhesive or the like. The deposition amount of the first fibers 1F is controlled by adjusting the discharge pressure of the mixed liquid 22, the applied voltage, the concentration of the raw material resin in the mixed liquid 22, the conveyance speed of the first porous sheet 2, and the like.

  The electrospinning mechanism for forming the first fiber 1F is not limited to the above configuration. The first fibers 1F and the adsorbent particles 4 are generated from the raw material liquid in the predetermined first fiber 1F generation space, and the first fibers 1F carrying the adsorbent particles 4 are deposited on the main surface of the first porous sheet 2. Any mechanism that can be used can be used without particular limitation. For example, the shape of the cross section perpendicular to the longitudinal direction of the emitter 23 may be a shape (V-type nozzle) that gradually decreases from the top to the bottom.

  After the fiber layer 1 is formed and before the second porous sheet 3 is laminated on the composite, the composite is heated to remove the liquid material remaining on the first fibers 1F and / or the adsorbent particles 4. May be performed. A heating apparatus is not specifically limited, What is necessary is just to select a well-known thing suitably. What is necessary is just to set heating temperature suitably according to the boiling point of each solvent, for example, what is necessary is just to heat so that the surface of the 1st porous sheet 2 may be about 100-200 degreeC.

  After the fiber layer 1 is formed, an adhesive for adhering the second porous sheet 3 may be applied to the composite of the first porous sheet 2 and the fiber layer 1 in a line shape. From the viewpoint of pressure loss, adsorption performance, and dust collection performance, it is preferable that a plurality of line-shaped adhesives are arranged at predetermined intervals.

The kind of adhesive agent is not specifically limited, For example, the hot-melt-adhesive etc. which have a thermoplastic resin as a main component are mentioned. Examples of the thermoplastic resin include polyurethane (PU), polyester such as PET, copolymer polyester such as urethane-modified copolymer polyester, PA, polyolefin (for example, PP, PE), and the like. The hot melt adhesive is applied, for example, in a line on the fiber layer 1 while being melted by heating, for example. The application amount of the adhesive is not particularly limited, but from the viewpoint of bonding strength and pressure loss, it is preferably 0.5 g / m ² or more and 15 g / m ² or less, preferably 1 g / m ² or more and 10 g / m ² or less. It is more preferable that it is 2 g / m ² or more and 6 g / m ² or less.

(Second lamination step)
Next, the composite is conveyed to the second porous sheet stacking unit 203. In the second porous sheet laminating unit 203, the second porous sheet 3 is supplied from the fiber layer 1 side of the composite and is laminated on the composite. The second porous sheet 3 can be a protective material that protects the fiber layer 1 from various external loads, and can be a cover that prevents the adsorbent particles 4 carried on the first fibers 1F from falling off. In addition, it may be a dust collector that captures dust. The material of the second porous sheet 3 will be described later. When the second porous sheet 3 is long, the second porous sheet 3 may be wound around the second supply reel 32 in the same manner as the first porous sheet 2. In this case, the second porous sheet 3 is laminated on the composite while being rolled out from the second supply reel 32.

  After laminating the second porous sheet 3, the fiber structure 10 is pressurized while applying pressure by a pair of pressure rollers 33 (33 a and 33 b) arranged above and below the fiber structure 10. The composite and the second porous sheet 3 may be further adhered.

  Finally, the fiber structure 10 is unloaded from the second porous sheet stacking unit 203 and is conveyed via the roller 41 to the collecting unit 204 disposed on the further downstream side. The collection unit 204 includes, for example, a collection reel 42 that scrapes off the conveyed fiber structure 10. The collection reel 42 is rotated by a motor 43.

  Hereinafter, the fiber structure 10 manufactured by the above method will be specifically described as a form suitable for a filter medium of an air cleaner with reference to the drawings. However, the use of the fiber structure 10 is limited to this. is not. FIG. 2 is a cross-sectional view schematically showing the fiber structure 10. FIG. 3 is a top view schematically showing the first fibers 1F constituting the fiber layer 1 and the adsorbent particles 4 carried thereon. The fiber structure 10 includes a fiber layer 1 including the first fibers 1F supporting the adsorbent particles 4, a first porous sheet 2 laminated on one main surface of the fiber layer 1, and the other of the fiber layers 1. A second porous sheet 3 laminated on the main surface.

(Fiber layer)
The fiber layer 1 is composed of the first fibers 1F and has a function of holding the adsorbent particles 4 and capturing dust. The average fiber diameter D1 of the first fibers 1F is preferably 3 μm or less, more preferably 1 μm or less, and particularly preferably 500 nm or less. Thereby, since the surface area is increased, the dust collection efficiency is increased, and dropping of the adsorbent particles 4 is suppressed. Further, the average fiber diameter D1 is preferably 50 nm or more, and more preferably 100 nm or more.

  The average fiber diameter D1 is an average value of the diameters of the first fibers 1F. The diameter of the first fiber 1F is a diameter of a cross section perpendicular to the length direction of the first fiber 1F. If such a cross section is not circular, the maximum diameter may be considered as the diameter. Moreover, you may consider that the width | variety of the direction perpendicular | vertical to the length direction of the 1st fiber 1F when the fiber layer 1 is seen from the normal line direction of one main surface is the diameter of the 1st fiber 1F. The average fiber diameter D1 is, for example, an average value of the diameters of arbitrary portions of any ten first fibers 1F included in the fiber layer 1. The same applies to average fiber diameters D2 and D3 described later.

The average mass per unit area of the fiber layer 1, 0.01 g / ^{m 2} or more, preferably 1.5 g / ^{m 2} or less, 0.01 g / ^{m 2} or more, 0.5 g / ^{m 2} or less More preferably, it is 0.03 g / m ² or more and 0.1 g / m ² or less. When the mass of the fiber layer 1 is within this range, high dust collection efficiency is easily exhibited while suppressing pressure loss.

  The thickness T1 of the fiber layer 1 is preferably 0.5 μm or more and 10 μm or less, more preferably 1 μm or more and 5 μm or less from the viewpoint of pressure loss. When the fiber layer 1 is a nonwoven fabric shape, the thickness T1 of the fiber layer 1 is, for example, the average value of the thicknesses at any 10 locations of the nonwoven fabric. The thickness is a distance between the two main surfaces of the nonwoven fabric. When the thickness T1 of the fiber layer 1 which is a nonwoven fabric is taken as a photograph of a cross-section of the nonwoven fabric, a line with the shortest distance is drawn from any one point on one main surface of the nonwoven fabric to the other main surface. It is calculated | required as the distance of the outer side (outer method) of two fibers in the most distant position among the fibers on this line. The thickness of the nonwoven fabric is calculated in the same manner for other arbitrary plural points (for example, 9 points), and a value obtained by averaging these is set as the thickness of the nonwoven fabric. In calculating the thickness, a binarized image may be used. The same applies to thicknesses T2 and T3 described later.

(First porous sheet)
The first porous sheet 2 is laminated on one main surface of the fiber layer 1.
The form and material of the 1st porous sheet 2 are not specifically limited, What is necessary is just to select suitably according to a use. Specific examples of the first porous sheet 2 include fiber structures such as woven fabrics, knitted fabrics, and nonwoven fabrics. Especially, it is preferable that the 1st porous sheet 2 is a nonwoven fabric from a viewpoint of pressure loss. When the 1st porous sheet 2 is a nonwoven fabric, the material of the 2nd fiber which comprises the 1st porous sheet 2 is not specifically limited, For example, glass fiber, a cellulose, an acrylic resin, PP, polyethylene (PE), PET , PA, or a mixture thereof. Especially, the point which is suitable as a base material WHEREIN: As a material of a 2nd fiber, PET or a cellulose is preferable. In particular, the first porous sheet 2 preferably contains PET and / or cellulose in a proportion of 80% by mass or more. When the 1st porous sheet 2 is a nonwoven fabric, the manufacturing method is not specifically limited, For example, a spun bond method, a dry method (for example, airlaid method), a wet method, a melt blow method, a needle punch method etc. are mentioned. In particular, the first porous sheet 2 is preferably a nonwoven fabric manufactured by a wet method.

  The average fiber diameter D2 of the second fibers is not particularly limited, and may be, for example, 1 μm or more and 40 μm or less, or 5 μm or more and 20 μm or less. The thickness T2 of the first porous sheet 2 is not particularly limited, and may be, for example, 50 μm or more and 500 μm or less, or 150 μm or more and 400 μm or less.

The mass per unit area of the first porous sheet 2 is not particularly limited, and may be, for example, 10 g / m ² or more and 80 g / m ² or less, or 35 g / m ² or more and 60 g / m ² or less. May be. The pressure loss of the first porous sheet 2 is not particularly limited. Especially, when the initial pressure loss of the 1st porous sheet 2 is measured using the measuring machine based on the standard of JISB9908 format 1, it is preferable that it is about 1 Pa or more and 10 Pa or less. When the initial pressure loss of the first porous sheet 2 is within this range, the pressure loss of the entire fiber structure 10 is also suppressed. The porosity of the first porous sheet 2 is not particularly limited, but is preferably 65% by volume or more and 98% by volume or less from the viewpoint of pressure loss. The porosity (volume%) is represented by, for example, (1−mass per apparent unit volume of first porous sheet 2 / specific gravity of second fiber) × 100.

(Second porous sheet)
The second porous sheet 3 is laminated on the side of the fiber layer 1 opposite to the first porous sheet 2 side.
The form and material of the 2nd porous sheet 3 are not specifically limited, What is necessary is just to select suitably according to a use. As the 2nd porous sheet 3, the fiber structure similar to the 1st porous sheet 2 can be illustrated. Especially, it is preferable that the 2nd porous sheet 3 is a nonwoven fabric from a viewpoint of pressure loss. When the 2nd porous sheet 3 is a nonwoven fabric, the material of the 3rd fiber which comprises the 2nd porous sheet 3 is not specifically limited, The same material as a 2nd fiber is mentioned. As will be described later, when the second porous sheet 3 is charged, PP is preferable as the material of the third fiber in that it is easily charged and the chargeability is easily maintained. The manufacturing method of the 2nd porous sheet 3 which is a nonwoven fabric is not specifically limited, either. Especially, it is preferable that the 2nd porous sheet 3 is manufactured by the melt blow method at the point which a thin fiber diameter suitable as a filter medium is easy to be formed.

  The second porous sheet 3 may be charged (permanently charged). That is, the 2nd porous sheet 3 may hold | maintain electric polarization semipermanently in the state where an external electric field does not exist, and may form the electric field with respect to the circumference | surroundings. As a result, the dust capturing performance is enhanced and the detachment of the adsorbent particles 4 is easily suppressed. In this case, the surface potential of the second porous sheet 3 (potential difference between the uncharged second porous sheet 3 and the charged second porous sheet 3) is not particularly limited, and is, for example, 5 kV or more, 100 kV. It may be the following.

  The average fiber diameter D3 of the third fibers is preferably larger than the average fiber diameter D1. The average fiber diameter D3 is, for example, 0.5 μm or more and 20 μm or less, and preferably 5 μm or more and 20 μm or less. The thickness T3 of the second porous sheet 3 is preferably 100 μm or more and 500 μm or less, and more preferably 150 μm or more and 400 μm or less from the viewpoint of pressure loss.

  The pressure loss of the second porous sheet 3 is not particularly limited. Especially, when the initial pressure loss of the 2nd porous sheet 3 is measured using the measuring machine based on the standard of JISB9908 format 1, it is preferable that it is about 1-10Pa. When the initial pressure loss of the second porous sheet 3 is within this range, the pressure loss of the entire fiber structure 10 is also suppressed.

Mass per unit area of the second porous sheet 3, from the viewpoint of pressure loss, 10 g / ^{m 2} or more, preferably 50 g / ^{m 2} or less, 10 g / ^{m 2} or more, is 30 g / ^{m 2} or less It is more preferable. The porosity of the second porous sheet 3 is not particularly limited, but from the viewpoint of pressure loss, it is preferably 60% by volume or more and 95% by volume or less, and more preferably 70% by volume or more and 90% by volume or less. preferable.

(Adsorbent particles)
The adsorbent particles 4 are supported on the first fibers 1F.
The adsorbent particles 4 can be supported on the first fibers 1F by, for example, the surface of the adsorbent particles 4 being bonded to the first fibers 1F. Further, the adsorbent particles 4 can be supported on the first fibers 1F by being wound around the first fibers 1F. Further, the adsorbent particles 4 can be carried on the first fibers 1F by penetrating the first fibers 1F. In particular, the adsorbent particles 4 wound or penetrated through the first fibers 1F are unlikely to fall off the fiber layer 1. Therefore, the adsorption performance by the adsorbent particles 4 can be maintained over a long period of time.

  As described above, the adsorbent particles 4 are supported on the first fibers 1F in various modes by using the mixed liquid containing the adsorbent and the raw material resin, and the adsorbent particles 4 and the first fibers 1F are the same. By generating in space.

  When the mixed liquid 22 containing the adsorbent and the raw material resin is released, if the adsorbent is released while wrapping the raw material resin of the first fiber 1F, the adsorbent that has wrapped the raw material resin of the first fiber 1F becomes particles. It tends to become a shape. Accordingly, the first fiber 1F is formed in a state that penetrates the adsorbent particles 4. Thereby, the adsorbent particle 4 (penetrating particle 4a) penetrated by the first fiber 1F is generated. In the penetrating particle 4a, it does not matter which part inside the first adsorbent particle 4 passes through the first fiber 1F. Further, when the adsorbent and the raw material resin of the first fiber 1F are released so as to be close to each other, the adsorbent becomes particulate and the raw resin is easily formed into a fiber shape so as to wind the adsorbent. As a result, adsorbent particles 4 wound around the first fibers 1F (hereinafter referred to as wound particles 4c) are generated. The wound particles 4c are wound, for example, spirally or more by the first fiber 1F. At this time, when the raw material resin is formed into a fiber shape without sufficiently winding the adsorbent, the first fiber 1F and the adsorbent particles 4 are respectively molded so as to be point-bonded. As a result, adsorbent particles 4 (hereinafter referred to as point-adhesive particles 4 b) whose surface adheres to the first fibers 1 F are generated. The point bonding particles 4b can be point bonded to the plurality of first fibers 1F.

  The generation ratio of the penetrating particles 4a, the point adhesion particles 4b, and the wound particles 4c is, for example, the concentration of the adsorbent in the mixed liquid 22, the form of the adsorbent in the mixed liquid 22 (whether dispersed or dissolved). It is controlled by adjusting the mass ratio between the dispersed adsorbent particles and the dissolved adsorbent, the size of the discharge port, the applied voltage, the discharge pressure, and the like. When making the production | generation ratio of the penetration particle | grains 4a larger than the wound particle | grains 4c, what is necessary is just to make the density | concentration of the adsorbent in the liquid mixture 22 into 0.8-2 times the density | concentration of raw material resin, for example. When the generation ratio of the wound particles 4c is larger than that of the point adhesion particles 4b, for example, the concentration of the adsorbent in the mixed liquid 22 is lower than the concentration of the raw resin (for example, the concentration of the adsorbent is the concentration of the raw resin). To 0.1 to 0.3 times as large as the above.

Although the adhering amount of the adsorbent particles 4 is not particularly limited, 0.1 to 30 g / m ² is preferable, 0.5 to 20 g / m ² is more preferable, and 1 to 10 g / m ² is preferable from the viewpoint of adsorption performance and pressure loss. ² is particularly preferred. The average particle diameter of the adsorbent particles 4 is not particularly limited, and is, for example, 0.1 μm or more and 100 μm or less, preferably 1 μm or more and 20 μm or less, more preferably 1 μm or more and 10 μm or less. The average particle diameter is an average value of the maximum diameters of ten adsorbent particles 4 when the fiber layer 1 having the adsorbent particles 4 is viewed from the normal direction of one main surface.

  The fiber structure 10 is pleated in a bellows shape, for example, and placed in an air cleaner as a filter medium. In this case, in terms of dust collection efficiency, the fiber structure 10 is preferably disposed between the air inlet and the air outlet so that the second porous sheet 3 is located on the air inlet side. The large dust is first captured by the second porous sheet 3, and then the finer dust is captured by the fiber layer 1, thereby increasing the dust collection efficiency.

  The method for producing a fiber structure of the present invention is highly productive and can be carried out at a low cost. Therefore, the filter medium of an air purifier or an air conditioner, a separation sheet for a battery, a membrane for a fuel cell, a pregnancy test sheet It is suitable as an in-vitro inspection sheet such as a cell culture, a medical sheet for cell culture, a dust-proof cloth such as a dust-proof mask, a dust-proof clothing, a cosmetic sheet, and a wiping sheet for wiping off dust.

DESCRIPTION OF SYMBOLS 10: Fiber structure 1: Fiber layer 1F: 1st fiber 2: 1st porous sheet 3: 2nd porous sheet 4: Adsorbent particle 4a: Penetrating particle 4b: Point adhesion particle 4c: Winding particle 200: Manufacture System 201: 1st porous sheet supply unit 202: Electrospinning unit 203: 2nd porous sheet lamination | stacking unit 204: Collection | recovery unit 11: Conveyance roller 12: 1st supply reel 13: Motor 21: Conveyor 22: Mixed liquid 23 : Emitter 24: First support 25: Second support 26: Voltage application device 27: Counter electrode 28: Pump 29: Liquid mixture tank 31: Transport roller 32: Second supply reel 33, 33 a, 33 b: Pressurization Roller 41: Roller 42: Collection reel 43: Motor

Claims (3)

A mixed solution containing a fiber raw resin, an adsorbent, and a liquid that dissolves the raw resin and dissolves or disperses the adsorbent, and a preparation step of preparing a first porous sheet;
A first laminating step of injecting the mixed liquid to form the fibers and depositing the fibers on one surface of the first porous sheet to form a fiber layer;
A second lamination step of laminating a second porous sheet on the fiber layer,
The manufacturing method of the fiber structure which makes the said fiber adsorbent carry | support the said adsorbent at the said 1st lamination process.   The manufacturing method of the fiber structure of Claim 1 whose average fiber diameter of the said fiber is 3 micrometers or less.   The method for producing a fiber structure according to claim 1 or 2, wherein the first lamination step is performed by an electrospinning method.

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