JP6508630B2 - Equipment for manufacturing laminated nonwoven fabric - Google Patents

Description

  The present invention has a first non-woven fabric as a base material, a second non-woven fabric including fibers laminated to the first non-woven fabric and having an adhesive attached thereto, and a third non-woven fabric as a protective layer stacked on the second non-woven fabric. The present invention relates to an apparatus for producing a laminated non-woven fabric.

  Nonwoven fabrics of fibers are used in various applications besides filter media. In recent years, from the viewpoint of increasing the surface area, it has been studied to use non-woven fabric using nanofibers having a fiber length of from nm to sub-μm order for various applications such as filter media.

  In Patent Document 1, from the viewpoint of enhancing form retention and handling of an ultrafine fiber non-woven fabric, binder particles are formed by applying an electric field to a binder solution, and the binder particles are brought into contact with ultrafine fibers formed by electrospinning. It has been proposed to bond and attach ultrafine fibers. Patent Document 2 proposes applying an electric field to attach an adhesive to the surface of a deposition member, and depositing a non-woven fabric on the surface of the deposition member by depositing nanofibers.

JP 2008-285793 A JP, 2009-263819, A

  In the methods of Patent Documents 1 and 2, when the mass per unit area of the non-woven fabric increases, it is difficult to increase the adhesive strength between the non-woven fabric serving as the base material and the non-woven fabric formed by electrospinning. In general, filter media applications such as air purifiers require low pressure drop. When producing a laminated non-woven fabric by pressure-bonding each layer, if the pressure-bonding load is too high or a large amount of adhesive is used, although the adhesive strength is improved, the pressure loss of the laminated non-woven fabric becomes high.

  An object of the present invention is to provide an apparatus for producing a laminated non-woven fabric useful for obtaining a laminated non-woven fabric capable of suppressing an increase in pressure loss and securing high adhesive strength between the non-woven fabrics.

One aspect of the present invention is a first nonwoven fabric supply unit for supplying a first nonwoven fabric to a production line;
A tank for containing a raw material liquid containing a raw material resin as a raw material of the second fiber and an adhesive;
The second fiber is generated by electrospinning the raw material liquid supplied from the tank, and the second fiber to which the particles of the adhesive are attached is deposited on the first nonwoven fabric to form the first nonwoven fabric. An electrospinning mechanism for laminating a second non-woven fabric containing two fibers;
A third non-woven fabric supply unit configured to supply a third non-woven fabric containing third fibers to the main surface of the second non-woven fabric opposite to the first non-woven fabric;
And a crimping part that crimps the second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric to form a laminated nonwoven fabric.
The pressure bonding portion includes a pressure bonding member including an embossed surface having a convex portion,
In the pressure-bonding section, at least one selected from the group consisting of the first fiber, the second fiber, and the third fiber is pressed against a part of particles of the adhesive by the convex portion of the embossed surface As a result, the first particles in which streak-like depressions are formed are formed, and the remaining particles of the adhesive are not formed in the streak-like depressions, and the convex of the embossed surface is formed as second particles. The second non-woven fabric is bonded to the first non-woven fabric and / or the third non-woven fabric via the first particles, and the number n _{2 of} the second particles is present. The present invention relates to an apparatus for manufacturing a laminated non-woven fabric having a number n ₁ of the first particles.

  In the production apparatus according to the present invention, it is possible to produce a laminated non-woven fabric having low pressure loss and high adhesive strength between non-woven fabrics.

It is a longitudinal cross-sectional view which shows typically the laminated nonwoven fabric obtained by the manufacturing apparatus of the laminated nonwoven fabric which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the manufacturing apparatus of the laminated nonwoven fabric which concerns on one Embodiment of this invention. It is a figure which shows the structural example of the manufacturing apparatus of the laminated nonwoven fabric which concerns on another embodiment of this invention. It is a schematic diagram for demonstrating a crimping | compression-bonding using a pair of pressure roller which one side has an embossing surface in a surrounding surface. It is a schematic diagram for demonstrating the crimping | compression-bonding using a pair of pressure roller which both have an embossing surface in a surrounding surface. BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows typically the air cleaner using the laminated nonwoven fabric obtained by the manufacturing apparatus which concerns on one Embodiment of this invention. It is the scanning electron microscope (SEM) photograph image | photographed from the 2nd nonwoven fabric side in the state which laminated | stacked the 2nd nonwoven fabric on the 1st nonwoven fabric in Example 1. FIG. It is the SEM photograph which peeled off the 3rd nonwoven fabric from the lamination nonwoven fabric of Example 1, and was photoed from the 2nd nonwoven fabric side.

(Production device for laminated nonwoven fabric)
A manufacturing apparatus (or manufacturing system) of a laminated nonwoven fabric according to an embodiment of the present invention is
(1) a first non-woven fabric supply unit for supplying a first non-woven fabric containing a first fiber to a production line;
(2) A tank for containing a raw material liquid containing a raw material resin as a raw material of the second fiber and an adhesive;
(3) The second fiber is generated by electrospinning the raw material liquid supplied from the tank, and the second fiber to which the adhesive particles are attached is deposited on the first nonwoven fabric, and the second nonwoven fabric is included in the first nonwoven fabric. An electrospinning mechanism for laminating a second non-woven fabric;
(4) A third non-woven fabric supply unit for supplying a third non-woven fabric containing third fibers to the main surface of the second non-woven fabric opposite to the first non-woven fabric;
(5) A pressure bonding unit that forms a laminated non-woven fabric by pressure-bonding the second non-woven fabric and the first non-woven fabric and / or the third non-woven fabric.
In the pressure-bonding section, at least one selected from the group consisting of the first fiber, the second fiber, and the third fiber is pressed against a part of the particles of the adhesive by the convex portion of the embossed surface. While the first particles having the depressions formed are formed, the remaining particles of the adhesive do not form streak-like depressions, and are positioned as the second particles at a position opposite to the area other than the projections of the embossed surface. The second non-woven fabric is bonded to the first non-woven fabric and / or the third non-woven fabric via the first particles. The number n _{2 of} second particles is greater than the number n _{1 of} first particles.

  In the laminated non-woven fabric, non-woven fabrics constituting each layer are adhered to each other by an adhesive. However, increased adhesive strength generally results in higher pressure drop in filter media applications such as air purifiers. In addition, when the mass per unit area of the non-woven fabric increases, it becomes more difficult to increase the adhesive strength between the layers. Also in such a case, if a large amount of adhesive is used to increase the adhesive strength, the mass of the laminated nonwoven fabric becomes large, or the adhesive spills out in the process of manufacturing the laminated nonwoven fabric. In addition, when the non-woven fabric is peeled off, when the laminated non-woven fabric is used as a filter medium, the dust collection efficiency is significantly reduced.

The streak-like depressions of the first particles are formed by pressing the fibers (the first fibers, the second fibers, and / or the third fibers) against the adhesive particles by the convex portions of the embossed surface of the pressure-bonding member. Fiber marks. It is preferable that fibers be embedded in the streak-like recess. By pressing the fibers, the first particles may be in a collapsed and spread state. According to the present embodiment, the second non-woven fabric and the first non-woven fabric and / or the third non-woven fabric are bonded via such first particles. Therefore, the laminated nonwoven fabric which has high adhesive strength can be obtained, and the peeling between each nonwoven fabric can be suppressed. On the other hand, at a position opposite to the area other than the convex portion, the adhesive particles are left as second particles without the fibers being pressed (or crushed), thereby preventing excessive adhesion, Pressure loss can be suppressed. Further, when the number n ₂ of the second particles is larger than the number n ₁ of the first particles, the effect of suppressing the pressure loss can be easily obtained. Therefore, the laminated nonwoven fabric which can be effectively used as a filter medium can be provided.

  As the pressure-bonding member, for example, a pair of pressure rollers are used. An embossed surface is provided on the peripheral surface of at least one of the pair of pressure rollers. When such a pressure roller is used, the laminate of the first laminate nonwoven fabric, the second nonwoven fabric and the third nonwoven fabric is supplied between a pair of rollers, and pressed by the circumferential surface of the roller, whereby the above-mentioned laminated nonwoven fabric is obtained. It can be easily obtained.

  FIG. 1: is a longitudinal cross-sectional view which shows typically the laminated nonwoven fabric obtained using the manufacturing apparatus which concerns on this embodiment. The laminated non-woven fabric 10 includes a first non-woven fabric 1, a second non-woven fabric 2 laminated on one main surface of the first non-woven fabric 1, and a second non-woven fabric laminated on the main surface opposite to the first non-woven fabric 1. 3 non-woven fabric 3 and an adhesive. The 1st nonwoven fabric 1 contains the 1st fiber, the 2nd nonwoven fabric 2 contains the 2nd fiber, and the 3rd nonwoven fabric 3 contains the 3rd fiber. Adhesive particles are attached to the second fibers.

  Hereinafter, although the manufacturing apparatus of a lamination | stacking nonwoven fabric is demonstrated, referring FIG. 2, the following manufacturing apparatuses do not limit this invention. FIG. 2: is a figure which shows roughly the structure of an example of the manufacturing apparatus of the laminated nonwoven fabric 10. As shown in FIG. The manufacturing apparatus 200 includes a manufacturing line for manufacturing the laminated nonwoven fabric 10.

  First, the first nonwoven fabric 1 is prepared. In the manufacturing apparatus 200, the first nonwoven fabric 1 is transported from the upstream side of the manufacturing line to the downstream side. At the uppermost stream of the manufacturing apparatus 200, a first non-woven fabric supply unit 201 in which the first non-woven fabric 1 wound in a roller shape is accommodated is provided. The first non-woven fabric supply unit 201 rotates the supply reel 12 by the motor 13 to supply the first non-woven fabric 1 wound around the supply reel 12 to the transport roller 11 of the manufacturing line.

  The first nonwoven fabric 1 is transported by the transport roller 11 to the electrospinning apparatus 202 provided with an electrospinning unit (not shown). The electrospinning mechanism included in the electrospinning unit includes an emitter 23 for discharging the raw material liquid containing the raw material resin of the second fiber and the adhesive, disposed above the inside of the device, and the discharged raw material liquid plus And a conveyer 21 for conveying the first non-woven fabric 1, which is disposed to face the emitter 23, from the upstream side to the downstream side. The transport conveyor 21 functions as a collector unit that collects the second fibers 2F together with the first nonwoven fabric 1. The number of electrospinning units is not particularly limited, and may be one or two or more.

  When there are a plurality of electrospinning units and / or emitters 23, the average fiber diameter of the second fiber 2F formed may be changed for each electrospinning unit or each emitter 23 as necessary. good. The average fiber diameter of the second fiber 2F is changed by adjusting the discharge pressure of the raw material liquid, the applied voltage, the concentration of the raw material liquid, the distance between the emitter 23 and the first non-woven fabric 1, the temperature, the humidity, etc. be able to. Further, the deposition amount of the second fiber 2F is controlled by adjusting the discharge pressure of the raw material liquid, the applied voltage, the concentration of the raw material liquid, the transport speed of the first non-woven fabric 1, and the like.

  On the side opposite to the main surface of the first nonwoven fabric 1 of the release body 23, a plurality of discharge ports (not shown) of the raw material liquid are provided. The distance between the outlet of the emitter 23 and the first nonwoven fabric 1 may be, for example, 100 to 600 mm, although it depends on the size of the manufacturing apparatus and the desired fiber diameter. The emitter 23 is disposed above the electrospinning unit, and the second support 25 extending downward from the first support 24 parallel to the conveyance direction of the first nonwoven fabric 1 has its own longitudinal direction as the first nonwoven fabric 1. It is supported so as to be parallel to the main surface of The first support 24 may be movable so as to swing the discharger 23 in a direction perpendicular to the transport direction of the first nonwoven fabric 1.

  The charging means is composed of a voltage application device 26 for applying a voltage to the emitter 23 and a counter electrode 27 installed in parallel with the transport conveyor 21. The counter electrode 27 is grounded. Thereby, a potential difference (for example, 20 kV 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. Further, instead of providing the counter electrode 27, the belt portion of the transport conveyor 21 may be made of a conductor.

  The emitter 23 is made of a conductor, has an elongated shape, and its inside is hollow. The hollow portion is a storage portion for storing the raw material liquid 22. The raw material liquid 22 is supplied from the raw material liquid tank 29 to the hollow of the discharge body 23 by the pressure of the pump 28 communicating with the hollow portion of the discharge body 23. Then, the raw material liquid 22 is discharged from the outlet toward the main surface of the first nonwoven fabric 1 by the pressure of the pump 28. The discharged raw material liquid 22 causes an electrostatic explosion while moving in the space (generation space) between the emitter 23 and the first non-woven fabric 1 in a charged state, and a fibrous material (second fiber 2F) Generate At this time, adhesive particles (and filaments of adhesive) are also produced and attached to the surface of the second fibers 2F. The generated second fibers 2F and adhesive particles (and filaments) are deposited on the first nonwoven fabric 1 to form the second nonwoven fabric 2.

  The electrospinning mechanism for forming the second fiber 2F to which the adhesive particles (and the filament) are attached is not limited to the above-mentioned configuration. The second fiber 2F and the adhesive particle (and filament) are produced from the raw material liquid 22 by electrostatic force in a predetermined fiber production space, and the second fiber 2F and adhesive particle (and filament) thus produced are As long as it is a mechanism that can be deposited on the main surface of the non-woven fabric 1, it can be used without particular limitation. The nozzle is not particularly limited, and may be, for example, a V-type nozzle, a needle-type nozzle, or the like in which the shape of the cross section perpendicular to the longitudinal direction of the emitter gradually decreases from the top to the bottom.

  Before laminating the third nonwoven fabric 3 on the second nonwoven fabric 2, the adhesive may be melted by the heating device 204 provided with the heater 42. The heating device 204 also removes the solvent contained in the second non-woven fabric 2. The manufacturing apparatus 200 does not necessarily include the heating device 204. However, in the case of including the heating device 204, in addition to facilitating the increase in the adhesive strength between the non-woven fabrics, the adhesive particles may come off in the subsequent steps. It can be suppressed.

  Next, the second nonwoven fabric 2 laminated on the first nonwoven fabric 1 is conveyed to the third nonwoven fabric laminating apparatus 205. In the third nonwoven fabric laminating apparatus 205, the third nonwoven fabric 3 is supplied to the main surface of the second nonwoven fabric 2 from above. When the third non-woven fabric 3 is long, the third non-woven fabric 3 may be wound around the reel 52 in the same manner as the first non-woven fabric 1. In this case, the third nonwoven fabric 3 is disposed on the main surface of the second nonwoven fabric 2 while being discharged from the reel 52.

  After disposing the third nonwoven fabric 3 on the main surface of the second nonwoven fabric 2, the resulting laminate is sandwiched and pressed by a crimping portion provided with a pair of pressure rollers 53 (53 a and 53 b) disposed above and below. At least one circumferential surface of the pressure roller 53a and 53b constitutes an embossed surface provided with a convex portion. Therefore, the fibers are pressed against (or embedded in) some of the adhesive particles by the projections to form the first particles. The second non-woven fabric 2 and the first non-woven fabric 1 and / or the third non-woven fabric 3 are bonded via the first particles (and the filament of the adhesive) to form a laminated non-woven fabric 10.

  Finally, the laminated nonwoven fabric 10 is carried out of the third nonwoven fabric laminating apparatus 205 and conveyed via the roller 61 to the collection apparatus 206 disposed further downstream. The collection device 206 incorporates, for example, a collection reel 62 for picking up the conveyed laminated nonwoven fabric 10. The recovery reel 62 is rotationally driven by a motor 63.

  Before forming the second nonwoven fabric 2, the first nonwoven fabric 1 may be transported to the adhesive spraying device, if necessary. In the adhesive spraying device, the adhesive is sprayed from above the first nonwoven fabric 1. The adhesive may be dispersed by, for example, a spray method, free fall, etc., but is applied to the main surface of the first nonwoven fabric 1 by electrospinning using an apparatus similar to or similar to the electrospinning apparatus 202. It is also good. Similarly, after forming the second non-woven fabric 2, the second non-woven fabric 2 laminated on the first non-woven fabric 1 may be transported to the adhesive spreading device as necessary. When a plurality of electrospinning devices 202 are provided, an adhesive spreading device may be provided between the plurality of electrospinning devices 202.

  FIG. 3: is a schematic diagram which shows the other structural example of the manufacturing apparatus of a lamination | stacking nonwoven fabric. In addition to the configuration of FIG. 2, the manufacturing apparatus of FIG. 3 includes an adhesive spreading device 203 before and after the electrospinning device 202, respectively. The adhesive spreading device 203 may be provided either before or after the electrospinning device 202. The adhesive spreading device 203 spreads the adhesive 4 using the adhesive solution 32 by the electrospinning method in the same principle as the electrospinning device 202. In addition, you may add a well-known additive, an antigelling agent, etc. to an adhesive agent solution.

  The first nonwoven fabric 1 is transported by the transport roller 11 to the adhesive spreading device 203. The electrospinning mechanism included in the adhesive spreading device 203 is a positive release agent 33 for releasing the adhesive solution 32 including the adhesive and the solvent disposed above in the device, and the released adhesive solution 32 as a plus. It comprises a charging means for charging, and a conveyer 31 which is disposed to face the emitter 33 and conveys the first nonwoven fabric 1 from the upstream side to the downstream side. The number of emitters 33 is not particularly limited, and may be one or two or more. A plurality of outlets (not shown) for the adhesive solution are provided on the side of the emitter 33 facing the main surface of the first nonwoven fabric 1. The discharge body 33 is provided with the second support 35 extending downward from the first support 34 disposed in the upper direction and parallel to the conveyance direction of the first nonwoven fabric 1. It is supported to be parallel. The first support 34 may be movable so as to swing the discharger 33 in a direction perpendicular to the transport direction of the first nonwoven fabric 1.

  The charging means is composed of a voltage application device 36 for applying a voltage to the emitter 33 and a counter electrode 37 installed in parallel to the conveyer 31. The counter electrode 37 is grounded. Instead of providing the counter electrode 37, the belt portion of the transport conveyor 31 may be made of a conductor. The emitter 33 is made of a conductor, has an elongated shape, and its inside is hollow. The hollow portion is a housing portion for housing the adhesive solution 32. The adhesive solution 32 is supplied from the adhesive solution tank 39 to the middle of the discharge body 33 by the pressure of the pump 38 communicating with the hollow portion of the discharge body 33. The adhesive solution 32 is discharged from the outlet toward the main surface of the first nonwoven fabric 1 by the pressure of the pump 38. The discharged adhesive solution 32 becomes particles of the adhesive 4 while moving in the space (generated space) between the emitter 33 and the first non-woven fabric 1 in a charged state. At this time, a thread of adhesive 4 may be formed. The particles of the adhesive 4 thus formed (and the filament of the adhesive 4) adhere to the main surface of the first nonwoven fabric.

The adhesive spreading device 203 disposed after the electrospinning device 202 is the same as the main surface of the second non-woven fabric 2 laminated on the first non-woven fabric 1 supplied from the electrospinning device 202 except that the adhesive 4 is dispersed. , The same as when placed in front of the electrospinning apparatus 202.
In the adhesive solution tank 39 and the raw material liquid tank 29, gelation of the adhesive 4 may be suppressed by continuously or completely stirring the adhesive solution 32 and the raw material liquid 22.

Below, the structure of a manufacturing apparatus and a laminated nonwoven fabric is demonstrated more concretely.
(Supply of the first non-woven fabric)
The first nonwoven fabric supply unit supplies the first nonwoven fabric upstream of the production line.
The first nonwoven fabric functions as a substrate that holds the shape of the laminated nonwoven fabric. In addition, when pleating laminated nonwoven fabric, a 1st nonwoven fabric becomes a base material, and maintains the shape of a pleat.

  The first non-woven fabric comprises a first fiber. The material of the first fiber is not particularly limited, and examples thereof include glass fiber, cellulose, acrylic resin, polyolefin, polyester, polyamide (PA) and the like. Examples of polyolefin include polypropylene (PP) and polyethylene (PE). Examples of polyester include polyethylene terephthalate (PET) and polybutylene terephthalate. The first fiber may contain one or more of these materials. Among these materials, cellulose, polyester and / or PA are preferable from the viewpoint of shape retention.

  The average fiber diameter D1 of the first fiber is not particularly limited, and may be, for example, 1 μm or more and 400 μm or less, and may be 5 μm or more and 200 μm or less.

  In addition, an average fiber diameter is an average value of the diameter of a fiber. The diameter of a fiber is the diameter of a cross section perpendicular to the longitudinal direction of the fiber. If such a cross section is not circular, the largest diameter may be considered as the diameter. Also, the width in the direction perpendicular to the longitudinal direction of the fibers when viewed from the normal direction of one of the main surfaces of the nonwoven fabric (or laminated nonwoven fabric) may be regarded as the diameter of the fibers. The average fiber diameter is, for example, an average value of diameters of arbitrary portions of any of plural (for example, 10) fibers contained in the non-woven fabric. The measurement of the fiber diameter can be performed, for example, using an electron micrograph of a non-woven fabric (or a laminated non-woven fabric) containing fibers. Thus, the average fiber diameter of the first fiber can be determined. The average fiber diameter of each of the second and third fibers can be determined in the same manner.

From the viewpoint of reducing the pressure loss as much as possible while securing the strength of the laminated nonwoven fabric, the mass per unit area of the first nonwoven fabric is preferably 10 g / m ² or more and 80 g / m ² or less, and 35 g / m 2 ² or more and more preferably 60 g / ^{m 2} or less. In addition, the mass per unit area may be an average value of the mass per unit area calculated for the area of the predetermined area of a plurality of places (for example, 10 places) of the first nonwoven fabric.

  The first nonwoven fabric is, for example, a nonwoven fabric manufactured by a spun bond method, a dry method (for example, air laid method), a wet method, a melt blow method, a needle punch method or the like, and the manufacturing method is not particularly limited. Among them, the first nonwoven fabric is preferably manufactured by a wet method in that a nonwoven fabric suitable as a base material is easily formed.

The pressure loss of the first nonwoven fabric is not particularly limited, but the initial pressure loss of the first nonwoven fabric is preferably about 1 Pa or more and 10 Pa or less. If the initial pressure loss of the first nonwoven fabric is in this range, the pressure loss of the entire laminated nonwoven fabric is also suppressed.
In the present specification, the pressure loss can be measured, for example, using a measuring device conforming to the standard of JIS B 9908 type 1.

(Raw material liquid)
The raw material liquid stored in the tank contains a raw material resin as a raw material of the second fiber and an adhesive.
The raw material resin (that is, the material of the second fiber) is not particularly limited. For example, PA, polyimide (PI), polyamide imide (PAI), polyether imide (PEI), polyacetal (POM), polycarbonate (PC), poly Ether ether ketone (PEEK), polysulfone (PSF), polyether sulfone (PES), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyarylate (PAR), polyacrylonitrile (PAN), polyvinylidene fluoride (polyvinylidene fluoride) Polymers such as PVDF), polyvinyl alcohol (PVA), polyvinyl acetate (PVAc), PP, PET, polyurethane (PU) and the like can be mentioned. The polymer may be either a homopolymer or a copolymer. Moreover, you may use the precursor of these polymers as raw material resin. For example, when the second fiber is made of PI, a PI precursor such as polyamic acid may be used as a raw resin. These raw material resins may be used alone or in combination of two or more. From the viewpoint of excellent electrospinning properties, PES is preferably used. PVDF is preferably used in that it is easy to reduce the average fiber diameter (average fiber diameter D2) of the second fiber.

The molecular weight of the raw material resin of the second fiber is preferably larger than the molecular weight of the resin constituting the adhesive. In particular, when the raw material resin of the second fiber and the resin constituting the adhesive are of the same type, the molecular weight of the raw resin is usually larger than the molecular weight of the resin constituting the adhesive. The difference between the weight average molecular weight Mw ₂ of the raw material resin of the second fiber and the weight average molecular weight M w _a of the resin constituting the adhesive: Mw ₂ -Mw _a is preferably 10000 or more, and 20000 or more or 50000 or more It may be.

  The type of the adhesive is not particularly limited, and examples thereof include a hot melt adhesive containing a thermoplastic resin as a main component. The hot melt adhesive may be either a reactive hot melt adhesive or a non-reactive hot melt adhesive. Specific examples of the hot melt adhesive include ethylene-vinyl acetate copolymer based adhesives, polyolefin based adhesives, polyester based adhesives, polyamide based adhesives, acrylic based adhesives, polyurethane based adhesives, and elastomer based adhesives. Etc. The thermoplastic resin contained in each adhesive may be either a homopolymer or a copolymer. For example, as a polyolefin adhesive, PE, PP, an olefin copolymer containing an ethylene unit or a propylene unit, etc. can be exemplified. Examples of polyester-based adhesives include polyalkylene terephthalates such as PET, and modified polyesters such as urethane-modified copolymer polyester. An adhesive may be used individually by 1 type and may be used in combination of 2 or more types.

  The raw material liquid usually contains a solvent in addition to the raw material resin of the second fiber and the adhesive. The solvent may be selected appropriately according to the type of raw resin and the production conditions. As the solvent, water or an organic solvent is used. The raw material liquid may contain one or more solvents.

  Examples of the organic solvent include alcohols, ethers, ketones, esters, carboxylic acids (such as formic acid and acetic acid), nitriles (such as acetonitrile), amides, nitrogen-containing heterocyclic compounds (such as pyridine), sulfoxides (such as dimethyl sulfoxide), and phenols. And hydrocarbons. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, hexafluoroisopropanol, tetraethylene glycol, triethylene glycol, dibenzyl alcohol and the like. As the ether, cyclic ethers such as 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran and the like are preferable. Examples of the ketone include acetone, hexafluoroacetone, methyl ethyl ketone, methyl isobutyl ketone, methyl n-hexyl ketone, methyl n-propyl ketone, diisopropyl ketone, diisobutyl ketone, cyclohexanone and the like. Examples of the ester include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, ethyl acetate, propyl acetate, methyl benzoate, ethyl benzoate, propyl benzoate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate and the like. . Examples of the amide include N, N-dimethylformamide, N, N-dimethylacetamide (DMAc) and the like. Examples of the hydrocarbon include hexane, cyclohexane, cyclopentane, benzene, toluene, xylene o-xylene, p-xylene, m-xylene and the like. From the viewpoint of easily dissolving the adhesive and the raw material resin such as PES, an amide such as DMAc is preferable. Amides are also suitable solvents for electrospinning.

  The raw material liquid can be prepared by dissolving the adhesive and the raw material resin in a solvent. When the raw material liquid contains an adhesive and a raw material resin, when depositing the second fiber and laminating the second nonwoven fabric, both the main surface opposite to the first nonwoven fabric and the main surface opposite to the first nonwoven fabric The adhesive is exposed. That is, since the adhesive is dispersed on both main surfaces of the second non-woven fabric, the second non-woven fabric and the second non-woven fabric may be provided without the step of spraying the adhesive before and / or after laminating the second non-woven fabric. The adhesive strength with the first nonwoven fabric and / or the third nonwoven fabric can be easily enhanced. Therefore, while being able to simplify the manufacturing process of a lamination nonwoven fabric, space saving of a manufacturing device is possible.

  Further, when a solution containing only an adhesive is used, there is a tendency to be easily gelled, but when the raw material liquid contains an adhesive and a raw material resin, gelation of the adhesive can be suppressed. The reason why the gelation is suppressed is not clear, but it is considered that the crystallization and the aggregation of the adhesive are suppressed by containing the raw material resin in addition to the adhesive in the raw material liquid.

  The raw material liquid may be prepared by mixing a first solution containing an adhesive and a first solvent for dissolving the adhesive, and a second solution containing a raw material resin and a second solvent for dissolving the raw resin. In this case, the time of the dissolution (preparation) step can be shortened, and a uniform solution can be produced. The first solution and the second solution are previously prepared prior to the preparation of the raw material solution. The first solvent and the second solvent may be appropriately selected from the solvents exemplified above according to the types of the adhesive and the raw material resin. The first solvent and the second solvent may be different. The first solvent and the second solvent are preferably compatible with each other, and may contain the same solvent, from the viewpoint of obtaining a uniform raw material liquid. When the first solvent and the second solvent contain the same solvent, solution preparation and nozzle cleaning can be facilitated. In consideration of the easiness of electrospinning etc., it is preferable that each of the first solvent and the second solvent is an amide such as DMAc or contains an amide such as DMAc.

  The ratio of the solvent in the raw material solution varies depending on the type of solvent selected, the type of adhesive and the raw material resin. The proportion of the solvent in the raw material liquid is, for example, 50% by mass to 95% by mass.

If necessary, known additives, an anti-gelling agent and the like may be added to the raw material liquid. An inorganic solid material may be added to the raw material liquid. Inorganic solid materials include, for example, inorganic compounds (eg, oxides, carbides, nitrides, borides, silicides, fluorides, sulfides) including metals and / or typical nonmetals (B, Si, P, As, etc.) Things etc.). It is preferable to use an oxide from the viewpoint of processability and the like. Specific examples of the oxide include Al ₂ O ₃ , SiO ₂ , TiO ₂ , MgO, and CaO. The inorganic solid material may be used alone or in combination of two or more.

  In the present invention, the gelation of the raw material liquid can be suppressed, but the degree of gelation of the raw material liquid can be measured by the viscosity change of the raw material liquid. For example, the increase rate of the viscosity of the raw material liquid to be subjected to electrospinning (for example, after 5 hours or more since the preparation of the raw material liquid) with respect to the viscosity (initial viscosity) immediately after the preparation of the raw material liquid is suppressed to 10% or less it can.

(Electrospinning)
In the electrospinning mechanism, the second fiber is formed by electrospinning (electrospinning) the raw material liquid supplied from the tank, and the second fiber to which the adhesive is attached is deposited on one main surface of the first nonwoven fabric. . Thereby, the second nonwoven fabric containing the second fibers is laminated on the first nonwoven fabric. In the electrospinning mechanism, a high voltage is applied to the raw material liquid, and the charged raw material liquid is discharged from the nozzle, whereby a second fiber is generated. At this time, the adhesive is also discharged from the nozzle and adheres to the second fiber. When the second nonwoven fabric is formed by the electrospinning mechanism, the second fibers are concentrated and deposited on the first fibers. Therefore, in addition to the adhesion of the non-woven fabrics to one another, the pressure loss can be further easily suppressed.

  Since the adhesive has lower spinnability than the raw material resin of the second fiber, the adhesive does not become a fibrous form as clean as the second fiber but becomes particulate. However, depending on the type of adhesive, electrospinning forms, together with the adhesive particles, a filament of adhesive connected to the adhesive particles. Since the adhesive has lower spinnability than the raw material resin of the second fiber, even if a filament is formed, its fiber diameter is extremely thin compared to the second fiber. As described above, when the raw material liquid is electrospinning by the electrospinning mechanism, the adhesive is dispersed in the entire second non-woven fabric, thereby suppressing the peeling between the second non-woven fabric and the first non-woven fabric and / or the third non-woven fabric. The effect of Although the reason why the spinnability of the adhesive is lower than that of the raw material resin for the second fiber is not clear, the difference in molecular weight between the adhesive (resin that constitutes the adhesive) and the raw material resin for the second fiber It is considered that the difference in the solubility of the compound and / or the difference in the interaction force between molecules etc. are affecting.

  The raw material liquid is preferably discharged from the nozzle in a direction perpendicular to the surface direction of the first nonwoven fabric. In this case, it is possible to suppress the spinning of the spun fibers, which is suitable for producing a relatively thin and homogeneous non-woven fabric. Note that the direction perpendicular to the surface direction of the first nonwoven fabric is not only the direction completely perpendicular but also a direction close to perpendicular (for example, a range of 70 ° to 100 ° with respect to the surface direction of the first nonwoven fabric) ) Shall also be included.

  In addition, after electrospinning the solution containing an adhesive agent to one main surface of a 1st nonwoven fabric and making an adhesive agent particle adhere as needed, you may laminate a 2nd nonwoven fabric as mentioned above. In addition, after laminating the second non-woven fabric to the first non-woven fabric, the solution containing the adhesive is electrospinning to adhere the adhesive particles to the main surface of the second non-woven fabric opposite to the first non-woven fabric. The third nonwoven fabric may be further laminated on the surface in the subsequent third nonwoven fabric supply unit. In these cases, peeling between the second nonwoven fabric and the first nonwoven fabric or the third nonwoven fabric can be further suppressed. Further, in the electrospinning process, since the solvent is removed in the process of forming the adhesive particles, it is not necessary to remove the solvent separately.

  The average fiber diameter D2 of the second fiber is preferably smaller than the average fiber diameter D1 of the first fiber (D1> D2). By including the relatively thin second fibers, the second non-woven fabric has a function of capturing dust in the laminated non-woven fabric.

  The average fiber diameter D2 is preferably 1/10 or less of the average fiber diameter D1 (D2 ≦ D1 / 10), and more preferably D2 ≦ D1 / 100. The average fiber diameter D2 is preferably 1/1000 or more of the average fiber diameter D1 (D1 / 1000 ≦ D2). When the average fiber diameter D2 is in this range, in addition to the ease of suppressing the pressure loss, the dust collection efficiency can be easily enhanced. Specifically, the average fiber diameter D2 is preferably 30 nm to 3 μm or 30 nm to 1 μm.

  The second fiber is preferably a nanofiber. In this case, the adhesive particles (in particular, the first particles) further facilitate adhesion of the non-woven fabrics to each other, so the effect of suppressing the peeling between the non-woven fabrics is enhanced. In addition, the dust collection efficiency can be further enhanced while suppressing the pressure loss. The average fiber diameter D2 of such a second fiber is, for example, 30 to 800 nm, and preferably 50 to 800 nm.

  When the adhesive is electrospinning with the raw resin of the second fiber using an electrospinning mechanism, adhesive particles are formed and attached to the second fiber when the second fiber is formed. By electrospinning the adhesive, the particle size of the adhesive particles can be reduced, and the adhesive can be finely and more uniformly dispersed. In addition, electrospinning of the adhesive facilitates concentration of the adhesive particles on the fibers. Therefore, while the effect which suppresses peeling with a 2nd nonwoven fabric, a 1st nonwoven fabric, and / or a 3rd nonwoven fabric increases, the control effect of a pressure loss can further be heightened.

  The adhesive may be further contained in the form of a filament in the laminated non-woven fabric. Electrospinning of the adhesive may result in the formation of adhesive particles as well as the formation of threads to draw threads from the adhesive particles. The thread may or may not be connected to the adhesive particle. In the case where the laminated non-woven fabric also contains such a filament in addition to the adhesive particles, it can be said that the adhesive is finely dispersed in the non-woven fabric. Therefore, the amount of adhesive used is at least easy to suppress peeling between the non-woven fabrics. In addition, the effect of suppressing an increase in pressure loss can be further enhanced. The filaments are preferably very thin and thinner than the second fibers. The average fiber diameter of the filament is, for example, 10 to 200 nm, and may be 10 to 100 nm. In addition, the average fiber diameter of a filament can be calculated | required according to the case of the average fiber diameter of a 1st fiber.

The initial pressure loss of the second nonwoven fabric is preferably about 5 Pa or more and 40 Pa or less.
Mass per unit area of the second nonwoven, from the viewpoint of efficiency of dust collection, 0.05 g / ^{m 2} or more, preferably 8 g / ^{m 2} or less, 0.5 g / ^{m 2} or more, 7 g / ^{m 2} or less It is further preferred that As described above, even when the mass per unit area of the second nonwoven fabric is large, the adhesion between the nonwoven fabrics can be suppressed by the adhesive particles adhering to the second fibers.

(Lamination of the third nonwoven fabric)
In the third non-woven fabric supply unit, the third non-woven fabric containing the third fibers is supplied to the other main surface (the main surface opposite to the first non-woven fabric) of the second non-woven fabric second non-woven fabric laminated on the first non-woven fabric , A laminate is obtained. The third nonwoven fabric has a function of collecting relatively large dust, and also functions as a protective material that protects the second nonwoven fabric from various external loads. From the viewpoint of dust collection efficiency, it is preferable that the third nonwoven fabric be subjected to charging treatment.

  In addition, before arrange | positioning a 3rd nonwoven fabric to a 2nd nonwoven fabric, you may make an adhesive fuse | melt by heating as needed. By melting the adhesive once, in addition to facilitating the placement of the third non-woven fabric, the falling off of the adhesive is suppressed. The adhesive particles (second particles) which are not pressed by the convex portions of the embossed surface in the pressure-bonding section are likely to come off, but once the adhesive is melted, the detachment of the adhesive is suppressed also in the subsequent steps .

  The heating of the adhesive can be performed, for example, using a heater or the like. The heating is preferably performed under the condition that the fibers (first and second fibers) constituting the non-woven fabric do not melt while melting the adhesive. Therefore, the heating temperature and the heating time may be appropriately selected according to the type of adhesive, the material of the first fiber and the second fiber, and the like.

  When heating the adhesive, it is sufficient to heat at least the second non-woven fabric side, but if heating is performed so as to melt the entire adhesive contained in the laminate of the first non-woven fabric and the second non-woven fabric, adhesion between the non-woven fabrics It is effective in enhancing sex. The heating may be performed so that the temperature of the main surface of the second nonwoven fabric opposite to the first nonwoven fabric is, for example, 100 to 200 ° C., preferably 120 to 170 ° C.

The 3rd nonwoven fabric laminated on the 2nd nonwoven fabric contains the 3rd fiber. The material of the third fiber is not particularly limited, and can be appropriately selected from the materials exemplified for the first nonwoven fabric. PP is preferable from the viewpoint of being easily charged.
The average fiber diameter D3 of the third fiber is not particularly limited. The average fiber diameter D3 is, for example, 0.5 μm or more and 20 μm or less, and 1 μm or more and 20 μm or less.

  The method for producing the third nonwoven fabric is not particularly limited, and the method exemplified for the first nonwoven fabric can be exemplified as well. Among them, the third nonwoven fabric is preferably produced by a melt-blowing method in that a thin fiber nonwoven fabric suitable as a filter medium is easily formed.

The pressure loss of the third nonwoven fabric is not particularly limited, but the initial pressure loss of the third nonwoven fabric is preferably about 10 Pa or more and 50 Pa or less. If the initial pressure loss of the third nonwoven fabric is in this range, the pressure loss of the entire laminated nonwoven fabric is also suppressed.
The mass per unit area of the third nonwoven fabric is also not particularly limited, and may be 10 g / m ² or more and 50 g / m ² or less, or 10 g / m ² or more and 30 g / m ² or less.

(Crimping)
In the pressure-bonding section, the laminate of the first non-woven fabric, the second non-woven fabric and the third non-woven fabric is pressed in the thickness direction on the embossing surface of the pressure-bonding member provided with the embossed surface having the convex portions to press-bond the non-woven fabrics. When the pressure bonding is performed using the embossed surface of the pressure bonding member, the convex portion of the embossed surface presses the fiber against a portion of the adhesive particles contained in the laminate to form a streak-like depression, As a result, the first particles are formed. And a 2nd nonwoven fabric, a 1st nonwoven fabric, and / or a 3rd nonwoven fabric are pasted up via this 1st particle. The remaining adhesive particles are present as the second particles as they are in the position opposed to the area other than the convex portion of the embossed surface without forming the streak-like depression. In each individual first particle, at least a part of the region of the particle may be crushed, or the entire particle may be crushed. Between the non-woven fabrics is adhered using point adhesion of the adhesive particles (first particles), and the peeling between the non-woven fabrics is suppressed.

Since the particle size of the adhesive particles is relatively small, even if it is difficult to bond the non-woven fabrics together by pressure bonding, fibers are embedded in a part of the adhesive particles by pressure bonding with a pressure bonding member having an embossed surface. The particles are formed, whereby the adhesion between the non-woven fabrics can be secured. On the other hand, when pressure bonding is performed with a smooth pressure bonding member under strong pressure, non-woven fabrics can be adhered to each other even if the particle size of the adhesive particles is small. However, the pressure drop of the laminated non-woven fabric tends to increase due to the fact that many adhesive particles are crushed and spread. Therefore, from the viewpoint of suppressing the pressure loss, the number n ₂ of the second particles is made larger than the number n ₁ of the first particles. In order to set n ₂ > n ₁ , for example, in the embossed surface, the area of the other area may be made larger than the area of the convex area.

  Crimping can be performed using a crimping member such as a roller. For example, the second non-woven fabric and the first non-woven fabric and / or the third non-woven fabric are adhered via an adhesive by sandwiching the laminate between a pair of pressure rollers and applying pressure by the rollers. However, the main surface (peripheral surface in the case of a roller) in contact with the laminate of the pressure-bonding members constitutes an embossed surface. Of the pair of rollers, an embossed surface may be provided on the peripheral surface of one of the rollers, and the peripheral surface of the other roller may be a smooth surface. Moreover, you may provide an embossing surface in each surrounding surface of both of a pair of rollers.

  FIG. 4 and FIG. 5 are each a schematic view for illustrating pressure bonding using a pressure roller having an embossed surface on its peripheral surface. In FIG. 4, of the pair of pressure rollers, one roller 153 a has an embossed surface having a plurality of projections 154 formed on the circumferential surface, and the circumferential surface of the other roller 153 b is a smooth surface. There is. Although FIG. 4 shows an example in which the upper roller 153a has an embossed surface, the present invention is not limited to this case, and the embossed surface may be disposed only on the lower roller. FIG. 5 shows an example in which an embossed surface is disposed on the peripheral surface of both of the pair of rollers 253a and 253b. The embossed surface of each of the rollers 253 a and 253 b has a plurality of convex portions 254.

  Crimping can be performed under heating. In the case of heating, it is efficient to press-bond with a heated roller. A heatable roller may be used as one of the pair of rollers, or heatable rollers may be used for both. In the case of using a roller having an embossed surface and a roller whose circumferential surface is a smooth surface, any roller may be heated. From the viewpoint of efficiently embedding the fibers in the adhesive particles, it is advantageous to use a heatable roller as a roller having an embossed surface. When the heating device 204 is not used, it is advantageous to perform pressure bonding under heating from the viewpoint of easily increasing the adhesive strength.

  When the laminate is pressed by the pressure-bonding member in a state in which the adhesive is melted in advance, the second non-woven fabric and the first non-woven fabric and / or the third non-woven fabric are bonded via the melted adhesive. In the crimping portion, crimping may be performed under heating as needed. In the case where the third non-woven fabric is disposed without melting the adhesive beforehand, it is preferable to perform heating when pressure bonding is performed. In this case, since it is not necessary to separately provide a heater for melting the adhesive on the upstream side of the pressure bonding portion, the space of the apparatus can be saved, and the manufacturing process can be simplified.

  When pressure bonding is performed under heating, the heating temperature is, for example, 40 to 200 ° C. In the case of pressure bonding with a roller, pressure bonding can be performed under heating by using a heatable roller. Examples of the heatable roller include a roller incorporating a heater and a roller capable of heating from a connected heater.

  In the embossed surface, the shape and distribution of the projections are not particularly limited. For example, the convex portion may be in a state in which a plurality of point-shaped convex portions are dispersed, or in a state in which a plurality of linear or strip convex portions are arranged. The arrangement of the linear or band-like convex portions is not particularly limited, and may be, for example, stripe or zigzag. For example, the belt-like sheet may be wound around the circumferential surface of the roller to form a convex portion, or the circumferential surface of the roller may be cut to form the convex portion. The point-like convex portion may be, for example, prismatic, cylindrical or elliptical. In addition, the convex portion may be formed in a lattice shape or a net shape.

From the viewpoint of easily adjusting the ratio n ₂ / n ₁ , the ratio S ₂ / S ₁ of the total area S ₂ of the other areas to the total area S ₁ of the convex area in the embossed surface is, for example, It is 1.1-10, and it is preferable that it is 1.2-5.
Further, from the viewpoint of easily improving the adhesiveness, the height of the convex portion on the embossed surface is preferably 100 to 5000 μm, and more preferably 200 to 1000 μm.

  The material of the pressure-bonding member such as a roller is not particularly limited as long as it has the hardness necessary for pressure-bonding, and for example, known materials used for pressure-bonding members such as resin, metal and ceramics are used. In the pressure-bonding member, a portion in contact with the laminated non-woven fabric (in the case of a roller, at least a circumferential surface or a convex portion on an embossed surface) may be formed of these materials.

In the laminated nonwoven fabric obtained by bonding, the ratio to the number n ₁ of the first particle number n ₂ of the second particles: n ₂ / n ₁ is preferably 1.1 to 10, in 1.2-5 It is further preferred that When the ratio n ₂ / n ₁ is in this range, it is easy to balance the adhesive strength and the pressure loss.

As n ₁ and n ₂ , in an electron micrograph of the laminated non-woven fabric, it was measured for an arbitrary region of a predetermined area (for example, 1 mm long × 1 mm wide, 10 mm long × 10 mm wide, 50 mm long × 50 mm wide) what is available, it may also be used in terms of the values of n ₁ and n ₂ in the entire laminated nonwoven fabric. In addition, an average value of values measured for a plurality of arbitrary regions may be used.

  It is preferable that the average particle diameter Dp of the second particles and the average fiber diameter D1 of the first fibers satisfy the relationship of D1> Dp. Here, although the average particle diameter of the second particles is described, it may be considered that the average particle diameter Dp of the second particles is approximately the same as the average particle diameter of the adhesive particles before pressing (embossing) by the embossing surface it can. When the average particle size of the adhesive particles before embossing satisfies the above relationship, adhesive particles having a small average particle size are attached to the second fibers having a small average fiber diameter. By forming streak-like depressions in a part of such adhesive particles to form the first particles, high adhesive strength is secured between the second non-woven fabric and the first non-woven fabric and / or the third non-woven fabric. It is possible to suppress peeling between the non-woven fabrics. Moreover, since each nonwoven fabric is adhere | attached using adhesive agent particles with a small average particle diameter, the increase in pressure loss can be suppressed.

  In addition, it is preferable that the average particle diameter Dp of the second particles (that is, the average particle diameter of the adhesive particles before embossing) and the average fiber diameter D2 of the second fibers satisfy the relationship of Dp> D2. In this case, even if the amount of adhesive used is small, many second fibers can be reinforced with adhesive particles at one time, so the adhesiveness can be further enhanced and it becomes easy to suppress peeling between non-woven fabrics.

The average particle diameter Dp of the second particles (that is, the average particle diameter of the adhesive particles before embossing) may be less than 1 μm, but is preferably 1 μm or more and 5 μm or more or 10 μm or more Is more preferred. The average particle diameter Dp is preferably 200 μm or less, and more preferably 150 μm or less or 100 μm or less. The lower limit value and the upper limit value can be arbitrarily combined. The average particle diameter Dp is, for example, 1 to 200 μm, and may be 5 to 150 μm or 10 to 100 μm.
In the case where the average particle diameter Dp of the second particles (that is, the average particle diameter of the adhesive particles before embossing) is in such a range, peeling between the non-woven fabrics can be further easily suppressed.

  The average particle diameter Dp of the second particles is an average value of the diameters of the second particles. If the cross-sectional shape of the second particles is not circular, then the largest diameter may be considered as the diameter. In addition, the diameter of the second particles when viewed from the normal direction of one of the main surfaces of the nonwoven fabric (or the laminated nonwoven fabric) may be regarded as the diameter of the second particles. The average particle diameter Dp is obtained, for example, by measuring diameters of a plurality of (for example, 10) particles arbitrarily selected in an electron micrograph of a non-woven fabric containing the second particles, and determining the average value thereof. If the particles are not spherical, the largest diameter may be considered as the diameter. Further, the average particle diameter of the adhesive particles before embossing may be measured in the same manner, and may be used as the average particle diameter Dp of the second particles.

  In the laminated nonwoven fabric, the thickness (T1) of the first nonwoven fabric is preferably 50 μm or more and 500 μm or less, more preferably 150 μm or more and 400 μm or less, from the viewpoint of suppressing an increase in pressure loss as much as possible.

  The thickness T2 of the second nonwoven fabric is preferably 0.5 μm or more and 50 μm or less (or 10 μm or less), and more preferably 1 μm or more and 5 μm or less, from the viewpoint of minimizing pressure loss. As described above, even when using a relatively thick (or large mass per unit area) second nonwoven fabric, adhesive particles having a small average particle diameter adhere to the second fibers, so that it is possible to obtain an inter-nonwoven fabric. Peeling can be suppressed.

  The thickness T3 of the third nonwoven fabric is not particularly limited, and may be 100 μm or more and 500 μm or less, and may be 150 μm or more and 400 μm or less.

  In the present specification, the thickness of the non-woven fabric is, for example, an average value of the thicknesses measured at arbitrary plural places (for example, 10 places) of the non-woven fabric in the laminated non-woven fabric. The thickness of the nonwoven fabric refers to the distance between the two major surfaces of the nonwoven fabric. Specifically, in the cross-sectional photograph of the laminated nonwoven fabric, when the thickness perpendicular to one surface is drawn from any one point on one principal surface of the nonwoven fabric to the other principal surface, the thickness of the nonwoven fabric is Among the fibers on this line, it is determined as the distance between the two fibers at the farthest position. The thickness of the non-woven fabric is similarly measured at other arbitrary plural points (for example, nine points), and the value obtained by averaging these is taken as the thickness of the non-woven fabric. However, since the thickness of the non-woven fabric is reduced in the area pressed by the projections of the embossed surface, the thickness of the non-woven fabric is measured in the area other than the area pressed by the projections. When calculating the thickness of the non-woven fabric, a binarized image may be used. Thus, the thickness T1 of the first nonwoven fabric, the thickness T2 of the second nonwoven fabric, and the thickness T3 of the third nonwoven fabric can be determined.

The average mass of the adhesive attached to the laminated non-woven fabric is not particularly limited, but is 0.5 g / m ² or more and 15 g / m ² or less from the viewpoint of easily obtaining high adhesion while reducing pressure loss. It is preferably 1 g / m ² or more and 10 g / m ² or less, and particularly preferably 3 g / m ² or more and 9 g / m ² or less.

In the laminated nonwoven fabric, the ratio of the total area s ₂ of the other areas to the total area s ₁ of the areas pressed by the convex portions of the embossed surface: s ₂ / s ₁ is, for example, 1.1 to 10 And 1.2 to 5. In the laminated nonwoven fabric, the average thickness of the area pressed by the convex portions of the embossed surface of the third nonwoven fabric is, for example, 50 to 95% of the thickness T3 of the third nonwoven fabric measured in the area other than this area. And preferably 60 to 80%. When the average thickness of the area pressed by the ratio s ₂ / s ₁ and / or the convex portion of the third nonwoven fabric is in such a range, the adhesive strength between the nonwoven fabrics can be easily enhanced while suppressing the pressure loss.

  The laminated nonwoven fabric obtained by using the manufacturing apparatus of the present invention has high adhesion strength between the second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric, and peeling is suppressed. In such a laminated non-woven fabric, the peel strength between the second non-woven fabric and each of the first non-woven fabric and the third non-woven fabric is, for example, 50 to 300 mN / 25 mm when measured by the method according to JIS Z0237. .

The laminated non-woven fabric is, for example,
Preparing a first nonwoven fabric containing a first fiber, a raw material liquid containing a raw material resin as a raw material of a second fiber, and an adhesive, and a third nonwoven fabric containing a third fiber (first step);
The raw material liquid is discharged from a nozzle by electrospinning (electro spinning) to form a second fiber to which adhesive particles adhere, and a second fiber to which adhesive particles adhere to a first non-woven fabric is deposited to form a second fiber. 1 step of laminating the second non-woven fabric on the non-woven fabric (second step);
The step (third step) of disposing a third nonwoven fabric including the third fibers on the main surface of the second nonwoven fabric opposite to the first nonwoven fabric to obtain a laminate, and pressure bonding including an embossed surface having a convex portion A pressing step (fourth step) of obtaining a laminated non-woven fabric by pressing the laminate in the thickness direction on the embossed surface of the member and pressing the second non-woven fabric against the first non-woven fabric and / or the third non-woven fabric; It can obtain by the manufacturing method provided.

(Air cleaner)
The laminated nonwoven fabric obtained by the manufacturing apparatus according to the present invention is particularly suitable for use as a filter material of an air cleaner. An air purifier comprising a laminated non-woven fabric is illustrated in FIG. The air cleaner 100 includes a gas suction unit 101, a gas discharge unit 102, and a laminated non-woven fabric 10 disposed between the gas suction unit 101 and the gas discharge unit 102. The laminated nonwoven fabric 10 may be pleated in a bellows shape. The laminated nonwoven fabric 10 is a filter medium that captures dust in the air. The air purifier provided with the laminated nonwoven fabric 10 has a small pressure loss and is excellent in dust collection efficiency. In terms of dust collection efficiency, the laminated nonwoven fabric 10 is preferably disposed between the suction portion 101 and the discharge portion 102 such that the second nonwoven fabric 3 is positioned on the suction portion 101 side.

  The air cleaner 100 takes in the outside air from the suction unit 101 into the air cleaner 100. The dust contained in the taken-in air is captured while passing through the laminated nonwoven fabric 10 and the like, and the cleaned air is discharged from the discharge part 102 to the outside. The air cleaner 100 may further include a prefilter 103 or the like for capturing large dust and the like between the suction portion 101 and the laminated nonwoven fabric 10. In addition, a deodorizing filter 104, a humidifying filter (not shown) or the like may be provided between the laminated nonwoven fabric 10 and the discharge part 102.

  Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
A laminated non-woven fabric was produced by the following procedure.
First, a first non-woven fabric (thickness: 300 μm, D: 1:15 μm, mass per unit area: 42 g / m ² ) formed of cellulose fiber, polyester fiber and acrylic fiber was prepared.
Using the manufacturing apparatus as shown in FIG. 2, the second non-woven fabric was deposited by depositing the second fibers with the adhesive particles and the filament of the adhesive attached to the first non-woven fabric being transported. The raw material liquid of the second fiber is a DMAc solution (first solution) containing an adhesive (polyester hot melt resin, melting point: about 100 ° C.) at a concentration of 20% by mass, and a DMAc solution containing PES at a concentration of 20% by mass A solution obtained by mixing (the second solution) at a mass ratio of 1: 1 was used. The average fiber diameter D2 of the obtained second fiber was 273 nm, and the average mass per unit area was 0.93 g / m ² .

  The SEM photograph image | photographed from the 2nd nonwoven fabric side is shown in FIG. As shown in FIG. 7, adhesive particles are attached to the second fiber, and a filament of the adhesive formed to draw a thread can also be observed.

Next, after heating from the second non-woven fabric side so that the surface of the second non-woven fabric becomes 158 ° C, a melt-blown non-woven fabric mainly composed of polypropylene fibers as the third non-woven fabric from the second non-woven fabric side (thickness: 165 μm, D3: 5 μm, unit Mass per area: 18 g / m ² ) was laminated. The obtained laminate was supplied between a pair of pressure rollers, and pressed in the thickness direction to be pressure-bonded to obtain a laminated nonwoven fabric. As one of the pair of pressure rollers, a roller having an embossed surface provided with a plurality of convex portions (cylindrical shape of diameter 5 mm × height 1 mm, distance between adjacent convex portions 10 mm) on the circumferential surface was used. The pressure of pressure bonding was 10 kPa.

A 30 cm square sample was cut out of the obtained laminated nonwoven fabric and folded in a pleated shape (pleated width: 2.5 cm). Next, the laminated non-woven fabric was expanded, and the surface on the third non-woven fabric side was confirmed with a microscope. As a result, lifting (peeling) of the third non-woven fabric was not confirmed. The thickness T2 of the second nonwoven fabric in the laminated nonwoven fabric (the average thickness of the second nonwoven fabric in the region other than the region pressed by the projections) was 2.3 μm.
Separately, the sample of width 25 mm x length 200 mm was cut out from the lamination | stacking nonwoven fabric. The peel strength between the first nonwoven fabric and the third nonwoven fabric of the sample was measured by the method according to JIS Z0237. The peel strength was 88 mN / 25 mm.

The laminated non-woven fabric was cut into 12 cm × 12 cm, and the dust in the air was sucked into the obtained sample at a surface air velocity of 5.3 cm / sec (suction test). The air pressure _{P 1} of the pressure _{P 0} and the downstream side of the upstream side of the sample was measured and was calculated pressure loss ₍₌ P 0 -P _1), was 48 Pa. In addition, the measuring machine (manometer) based on the specification of JISB9908 was used for the measurement of air pressure.

FIG. 8 is an SEM photograph taken from the side of the second nonwoven fabric after peeling off the third nonwoven fabric from the laminated nonwoven fabric. In the area to the left of the picture, small adhesive particles maintain the spherical shape (second particles), whereas in the area to the right, the adhesive particles collapse and spread, and fibers are embedded. A ridge-like recess is formed, and the adhesive particle and the fiber are in a bonded state (first particle). The portion where the fiber is embedded in the adhesive particle corresponds to the convex portion of the embossed surface of the pressure roller, and the portion where the spherical shape of the adhesive particle is maintained corresponds to the area other than the convex portion. ing. 3. The number n ₁ of the first particles and the number n ₂ of the second particles were measured for a region of 10 mm in length × 10 mm in width arbitrarily selected in the SEM photograph, and the n ₂ / n ₁ ratio was determined. It was four.

(Reference Example 1)
A laminated non-woven fabric was obtained in the same manner as in Example 1 except that a pair of pressure rollers having a smooth surface was used as the pressure-bonding member.
A 30 cm square sample was cut out of the obtained laminated nonwoven fabric. As in Example 1, the obtained sample was folded into a pleated shape, and then spread, and the surface on the third non-woven fabric side was confirmed with a microscope, but no floating (peeling) of the third non-woven fabric was observed. Separately, the peel strength and the pressure loss were measured by the same method as in Example 1 to be 210 mN / 25 mm and 72 Pa, respectively. The third nonwoven fabric was peeled off from the laminated nonwoven fabric, a SEM photograph was taken from the second nonwoven fabric side, and the adhesive particles were observed in the SEM photograph. As a result, almost all of the adhesive particles were the first particles.

(Reference Example 2)
A laminated non-woven fabric was obtained in the same manner as in Example 1 except that a pair of pressure rollers having a smooth peripheral surface was used as the pressure-bonding member, and the pressure of pressure-bonding was changed to 1 kPa.
A 30 cm square sample was cut out of the obtained laminated nonwoven fabric. As in Example 1, the obtained sample was folded into a pleated shape, and then spread, and the surface on the third non-woven fabric side was confirmed with a microscope. As a result, floating (peeling) of the third non-woven fabric was confirmed. Separately, the peel strength and the pressure loss were measured by the same method as in Example 1 to be 19 mN / 25 mm and 46 Pa, respectively. The third nonwoven fabric was peeled off from the laminated nonwoven fabric, and a SEM photograph was taken from the second nonwoven fabric side. In this SEM photograph, the adhesive particles were observed. As a result, almost all of the adhesive particles were second particles.

  ADVANTAGE OF THE INVENTION According to the manufacturing apparatus of this invention, pressure loss and peeling between nonwoven fabrics are suppressed, and a laminated nonwoven fabric useful as a filter material of an air cleaner or an air conditioner can be obtained. The laminated non-woven fabric is not only used as a filter material, but also as a separation sheet for batteries, membranes for fuel cells, extracorporeal examination sheets such as pregnancy test sheets, medical sheets for cell culture, etc., dustproof cloths such as dust masks, dustproof clothes It can also be used as a cosmetic sheet, a wiping sheet for wiping dust, and the like.

1: 1st nonwoven fabric, 2F: 2nd fiber, 2: 2nd nonwoven fabric, 3: 3rd nonwoven fabric, 10: laminated nonwoven fabric, 11: transport roller, 12: supply reel, 13: motor, 21, 31: transport conveyor, 22: raw material liquid, 32: adhesive solution, 23, 33: emitter, 24, 34: first support, 25, 35: second support, 26, 36: voltage application device, 27, 37: counter electrode 28, 38: pump, 29: raw material liquid tank, 39: adhesive solution tank, 41: transport roller, 42: heater, 51: transport roller, 52: reel, 53, 53a, 53b, 153a, 153b, 253a, 253b: pressure roller, 154, 254: convex portion of embossed surface, 61: roller, 62: recovery reel, 63: motor, 100: air cleaner, 101: suction portion, 102: discharge portion, 103: prefill Ta: 104: Deodorant filter, 200: Production device (production system), 201: First non-woven fabric supply unit, 202: Electrospinning device, 203: Adhesive spreading device, 204: Heating device, 205: Third non-woven fabric laminating device , 206: recovery device

Claims (8)

A first non-woven fabric supply unit for supplying a first non-woven fabric containing a first fiber to a production line;
A tank for containing a raw material liquid containing a raw material resin as a raw material of the second fiber and an adhesive;
The second fiber is generated by electrospinning the raw material liquid supplied from the tank, and the second fiber to which the particles of the adhesive are attached is deposited on the first nonwoven fabric to form the first nonwoven fabric. An electrospinning mechanism for laminating a second non-woven fabric containing two fibers;
A third non-woven fabric supply unit configured to supply a third non-woven fabric containing third fibers to the main surface of the second non-woven fabric opposite to the first non-woven fabric;
And a crimping part that crimps the second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric to form a laminated nonwoven fabric.
The pressure bonding portion includes a pressure bonding member including an embossed surface having a convex portion,
In the pressure-bonding section, at least one selected from the group consisting of the first fiber, the second fiber, and the third fiber is pressed against a part of particles of the adhesive by the convex portion of the embossed surface As a result, the first particles in which streak-like depressions are formed are formed, and the remaining particles of the adhesive are not formed in the streak-like depressions, and the convex of the embossed surface is formed as second particles. The second non-woven fabric is bonded to the first non-woven fabric and / or the third non-woven fabric via the first particles, and the number n _{2 of} the second particles is present. The manufacturing apparatus of the laminated nonwoven fabric which is more than the number n ₁ of said 1st particle | grains. The pressure bonding member is a pair of pressure rollers,
The manufacturing apparatus of the laminated nonwoven fabric of Claim 1 in which the said embossing surface is provided in the surrounding surface of at least one pressure roller of the said pair of pressure rollers. The ratio to the number n ₁ of the first particle number n ₂ of the second particles: n ₂ / n ₁ is 1.1 to 10, apparatus for manufacturing a laminated nonwoven fabric according to claim 1 or 2.   The manufacturing apparatus of the laminated nonwoven fabric of any one of Claims 1-3 whose said 2nd fiber is a nanofiber. The average fiber diameter D1 of the first fiber and the average fiber diameter D2 of the second fiber satisfy the relationship D1> D2,
The manufacturing apparatus of the laminated nonwoven fabric of any one of Claims 1-4 with which the average particle diameter Dp of said 2nd particle | grains and the average fiber diameter D1 of a said 1st fiber satisfy | fill the relationship of D1> Dp.   The manufacturing apparatus of the laminated nonwoven fabric of Claim 5 with which the average particle diameter Dp of the said 2nd particle | grains and the average fiber diameter D2 of the said 2nd fiber satisfy | fill the relationship of Dp> D2.   The manufacturing apparatus of the laminated nonwoven fabric of Claim 5 or 6 whose average particle diameter Dp of said 2nd particle | grain is 1-200 micrometers. The laminated non-woven fabric further comprises a filament of the adhesive,
The manufacturing apparatus of the laminated nonwoven fabric of any one of Claims 1-7 in which the said filament is connected with the particle | grains of the said adhesive agent.