JP2017101346A - Laminate nonwoven fabric and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate nonwoven fabric capable of suppressing increase of pressure loss and securing high adhesive strength between nonwoven fabrics.SOLUTION: A laminate nonwoven fabric 10 comprises: a first nonwoven fabric 1 that contains a first fiber; a second nonwoven fabric 2 that is laid on the first nonwoven fabric 1 and contains a second fiber; a third nonwoven fabric 3 that is laid on a principal surface of the second nonwoven fabric 2 on the opposite side of the first nonwoven fabric and contains a third fiber; and an adhesive. Particles of the adhesive adhere to the second fiber. The particles of the adhesive include first particles each having a stripe-shaped concavity and second particles other than the first particles. The number nof the second particles is larger than the number nof the first particles. The second nonwoven fabric 2, the first nonwoven fabric 1 and/or the third nonwoven fabric 3 are attached to each other through the first particles.SELECTED DRAWING: Figure 1

Description

  This invention has the 1st nonwoven fabric used as a base material, the 2nd nonwoven fabric containing the fiber which was laminated | stacked on the 1st nonwoven fabric, and the adhesive agent adhered, and the 3rd nonwoven fabric used as the protective layer laminated | stacked on the 2nd nonwoven fabric. The present invention relates to a laminated nonwoven fabric and a method for producing the laminated nonwoven fabric.

  Fiber nonwoven fabrics are used for various purposes in addition to filter media. In recent years, from the viewpoint of increasing the surface area, it has been studied to use a nonwoven fabric using nanofibers having a fiber diameter on the order of nm to sub-μm for various uses such as filter media.

  In Patent Document 1, from the viewpoint of improving the shape retention and handling of the ultrafine fiber nonwoven fabric, binder particles are formed by applying an electric field to the binder solution, and the binder particles are brought into contact with the ultrafine fibers formed by electrospinning. It has been proposed to bond ultrafine fibers. Patent Document 2 proposes that an electric field is applied to adhere an adhesive to the surface of the deposition member, and further nanofibers are deposited to laminate the nonwoven fabric on the surface of the deposition member.

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 nonwoven fabric increases, it is difficult to increase the adhesive strength between the nonwoven fabric that is the base material and the nonwoven fabric that is formed by electrospinning. Generally, low pressure loss is required for filter media applications such as air purifiers. When a laminated nonwoven fabric is produced by pressure bonding each layer, if the pressure bonding load is too high or a large amount of adhesive is used, the adhesive strength is improved, but the pressure loss of the laminated nonwoven fabric increases.

  The objective of this invention is providing the manufacturing method of a laminated nonwoven fabric which can suppress the increase in a pressure loss, and can ensure the high adhesive strength between nonwoven fabrics, and a laminated nonwoven fabric.

One aspect of the present invention is a first non-woven fabric containing first fibers,
A second nonwoven fabric laminated on the first nonwoven fabric and containing second fibers;
A third nonwoven fabric laminated on the main surface of the second nonwoven fabric opposite to the first nonwoven fabric and containing third fibers;
An adhesive, and
The adhesive particles are attached to the second fibers,
The adhesive particles include first particles having streak-like depressions and other second particles.
The number n ₂ of the second particles is larger than the number n _{1 of} the first particles,
The present invention relates to a laminated nonwoven fabric in which the second nonwoven fabric is bonded to the first nonwoven fabric and / or the third nonwoven fabric via the first particles.

Another aspect of the present invention provides a first nonwoven fabric containing first fibers, a raw material liquid containing a raw material resin and an adhesive as raw materials for the second fibers, and a third nonwoven fabric containing third fibers. And a process of
By electrospinning, the raw material liquid is discharged from a nozzle to generate the second fibers to which the adhesive particles are adhered, and the second fibers to which the adhesive particles are adhered are deposited on the first nonwoven fabric. And laminating the second nonwoven fabric on the first nonwoven fabric,
A step of obtaining a laminate by disposing a third nonwoven fabric containing third fibers on the main surface of the second nonwoven fabric opposite to the first nonwoven fabric;
Pressing the laminate in the thickness direction on the embossed surface of the pressure-bonding member having an embossed surface having a convex portion, and crimping the second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric. A crimping step for obtaining a laminated nonwoven fabric,
In the crimping step, 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 adhesive particles by the convex portion of the embossed surface. The first particles in which the streak-like dents are formed are formed, and the remaining particles of the adhesive are not formed in the streak-like dents, and the convex portions of the embossed surface are formed as second particles. The second non-woven fabric, the first non-woven fabric and / or the third non-woven fabric are bonded via the first particles, and the number n ₂ of the second particles is Further, the present invention relates to a method for producing a laminated nonwoven fabric, which is larger than the number n ₁ of the first particles.

  In the laminated nonwoven fabric according to the present invention, the pressure loss is kept low, and high adhesive strength between the nonwoven fabrics can be ensured.

It is a longitudinal section showing typically the lamination nonwoven fabric concerning one embodiment of the present 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 the crimping | compression-bonding using a pair of press roller which one 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. It is a perspective view which shows typically the air cleaner using the laminated nonwoven fabric which concerns on one Embodiment of this invention. It is a 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 a 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.

(Laminated nonwoven fabric)
The laminated nonwoven fabric which concerns on one Embodiment of this invention is the other side of the 1st nonwoven fabric containing a 1st fiber, the 2nd nonwoven fabric laminated | stacked on a 1st nonwoven fabric and containing a 2nd fiber, and the 1st nonwoven fabric of a 2nd nonwoven fabric. 3rd nonwoven fabric which is laminated | stacked on the main surface and contains a 3rd fiber, and an adhesive agent are provided. Adhesive particles are attached to the second fibers, and the adhesive particles include first particles having a streak-like depression and other second particles. The number n ₂ of the second particles is larger than the number n _{1 of} the first particles, and the second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric are bonded via the first particles.

  In the laminated nonwoven fabric, the nonwoven fabrics constituting each layer are bonded to each other with an adhesive. However, increasing the adhesive strength generally increases the pressure loss in filter media applications such as air purifiers. Moreover, when the mass per unit area of a nonwoven fabric becomes large, it will become further difficult to raise the adhesive strength between each layer. Even in such a case, if a large amount of adhesive is used to increase the adhesive strength, the mass of the laminated nonwoven fabric increases, or the adhesive spills off during the production process of the laminated nonwoven fabric. Moreover, when a nonwoven fabric peels, when a laminated nonwoven fabric is used as a filter medium, dust collection efficiency will fall remarkably.

The streak-like dents of the first particles are fiber marks formed by pressing fibers (first fibers, second fibers, and / or third fibers) against the adhesive particles. It is preferable that fibers are embedded in the streak-like dent. The first particles may be in a state of being crushed and expanded by pressing the fibers. According to this embodiment, since such 1st particle | grains are formed, a 2nd nonwoven fabric and a 1st nonwoven fabric and / or a 3rd nonwoven fabric are adhere | attached through this 1st particle | grain. Thereby, since high adhesive strength is securable, peeling between each nonwoven fabric can be suppressed. On the other hand, the second particles other than the first particles remain without the fibers being pressed (or not crushed), thereby preventing excessive adhesion, thereby suppressing pressure loss. In addition, since 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, so that the laminated nonwoven fabric can be effectively used as a filter medium.

  As will be described later, the first particles are formed by pressing a laminate of the first nonwoven fabric, the second nonwoven fabric, and the third nonwoven fabric using a pressure-bonding member having an embossed surface having convex portions. When a laminate is pressed using a pressure-bonding member having an embossed surface, fibers are pressed against adhesive particles existing in a region facing the convex surface of the embossed surface, and a streak-like dent that forms a fiber trace is formed. Thus, the first particles are formed. Further, the remaining adhesive particles are present at positions facing areas other than the convex portions of the embossed surface as second particles in which no streak-like depressions are formed (or not crushed).

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, more preferably from 1.2 to 5. When the ratio: n ₂ / n ₁ is in such a range, it is easy to balance the adhesive strength and the pressure loss.

Each of n ₁ and n ₂ was measured for an arbitrary area of a predetermined area (for example, a size of 1 mm in length × 1 mm in width, 10 mm in length × 10 mm in width, 50 mm in length × 50 mm in width) in the electron micrograph of the laminated nonwoven fabric. 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. Moreover, you may utilize the average value of the value measured about several arbitrary area | regions.

  The second fiber is preferably a nanofiber. In this case, since it becomes easy to adhere | attach nonwoven fabrics with adhesive particle | grains (especially 1st particle | grains), the effect which suppresses peeling between nonwoven fabrics increases. Moreover, an increase in pressure loss can be further suppressed.

  The average fiber diameter D1 of the first fibers and the average fiber diameter D2 of the second fibers satisfy the relationship of D1> D2, and the average particle diameter Dp of the second particles and the average fiber diameter D1 of the first fibers are D1> It is preferable to satisfy the relationship of Dp. Although the average particle diameter Dp of the second particles has been described, it can be considered that the average particle diameter Dp of the second particles is substantially the same as the average particle diameter of the adhesive particles before embossing. When the average particle diameter of the adhesive particles before embossing satisfies the above relationship, the adhesive particles having a small average particle diameter are attached to the second fibers having a small average fiber diameter. A high degree of adhesive strength is ensured between the second nonwoven fabric, the first nonwoven fabric, and the third nonwoven fabric by forming the first particle by forming a streak-like depression in a part of such adhesive particles. It is possible to suppress peeling between the nonwoven fabrics. Moreover, since each nonwoven fabric is adhere | attached using adhesive particle | grains with a small average particle diameter, the increase in pressure loss can be suppressed.

  The average fiber diameter is an average value of fiber diameters. The diameter of the fiber is a diameter of a cross section perpendicular to the length direction of the fiber. If such a cross section is not circular, the maximum diameter may be considered as the diameter. Further, the width in the direction perpendicular to the longitudinal direction of the fiber when viewed from the normal direction of one main surface of the nonwoven fabric (or laminated nonwoven fabric) may be regarded as the fiber diameter. The average fiber diameter is, for example, an average value of the diameters of arbitrary portions of arbitrary plural (for example, 10) fibers included in the nonwoven fabric. The measurement of the fiber diameter can be performed using, for example, an electron micrograph of a nonwoven fabric (or laminated nonwoven fabric) containing fibers. In this way, the average fiber diameter of each of the first fiber, the second fiber, and the third fiber can be obtained.

  The average particle diameter Dp of the second particles is an average value of the diameters of the second particles. When the cross-sectional shape of the second particle is not circular, the maximum diameter may be regarded as the diameter. In addition, the diameter of the second particle when viewed from the normal direction of one main surface of the nonwoven fabric (or laminated nonwoven fabric) may be regarded as the diameter of the second particle. For example, in the electron micrograph of the nonwoven fabric containing the second particles, the average particle diameter Dp is obtained as an average value of a plurality of (for example, 10) arbitrarily selected particles by measuring the diameter. If the particles are not spherical, the maximum diameter may be considered the diameter. Moreover, about the adhesive particle before embossing, you may measure an average particle diameter in the same procedure, and may use it as the average particle diameter Dp of a 2nd particle.

  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 Dp> D2. In this case, even if the amount of the adhesive used is small, many second fibers can be reinforced at once with the adhesive particles, so that the adhesiveness can be further enhanced and the peeling between the nonwoven fabrics can be easily suppressed.

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, preferably 1 μm or more, and 5 μm or more or 10 μm or more. Is more preferable. The average particle diameter Dp is preferably 200 μm or less, and more preferably 150 μm or less or 100 μm or less. These lower limit value and 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.
When 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 nonwoven fabrics can be further suppressed.

  The adhesive may be further included in the laminated nonwoven fabric in the form of a filament. The filamentous body may or may not be linked to the adhesive particles. Particulate and filamentary adhesives can be formed by treating the adhesives by electrospinning. When the laminated nonwoven fabric includes such a thread in addition to the adhesive particles, it can be said that the adhesive is finely dispersed in the nonwoven fabric. Therefore, the amount of the adhesive used is at least easy to suppress peeling between the nonwoven fabrics. Moreover, the effect which suppresses the increase in pressure loss can further be heightened.

  FIG. 1 is a longitudinal sectional view schematically showing a laminated nonwoven fabric according to this embodiment. The laminated nonwoven fabric 10 includes a first nonwoven fabric 1, a second nonwoven fabric 2 laminated on one principal surface of the first nonwoven fabric 1, and a second nonwoven fabric laminated on the principal surface opposite to the first nonwoven fabric 1. 3 The nonwoven fabric 3 and an adhesive agent are provided. The first nonwoven fabric 1 includes first fibers, the second nonwoven fabric 2 includes second fibers, and the third nonwoven fabric 3 includes third fibers. Adhesive particles are attached to the second fibers.

Below, the structure of a laminated nonwoven fabric is demonstrated more concretely.
(First non-woven fabric)
The first nonwoven fabric functions as a base material that maintains the shape of the laminated nonwoven fabric. In addition, when pleating a laminated nonwoven fabric, a 1st nonwoven fabric becomes a base material and maintains the shape of a pleat.
The first nonwoven fabric includes first fibers. The material of the first fiber is not particularly limited, and examples thereof include glass fiber, cellulose, acrylic resin, polyolefin, polyester, and polyamide (PA). Examples of the polyolefin include polypropylene (PP) and polyethylene (PE). Examples of the polyester include polyethylene terephthalate (PET) and polybutylene terephthalate. The first fiber may contain one or more of these materials. Of these materials, cellulose, polyester, and / or PA are preferable from the viewpoint of shape retention.

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

  The first nonwoven fabric is a nonwoven fabric produced by, for example, a spunbond method, a dry method (for example, airlaid method), a wet method, a melt blow method, a needle punch method, and the production method is not particularly limited. Especially, it is preferable that a 1st nonwoven fabric is manufactured by the wet method at the point which the nonwoven fabric suitable as a base material is easy to be 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 within this range, the pressure loss of the entire laminated nonwoven fabric is also suppressed.
In addition, in this specification, a pressure loss can be measured using the measuring machine based on the standard of JISB9908 format 1, for example.

  The thickness (T1) of the first nonwoven fabric is preferably 50 μm or more and 500 μm or less, and 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.

  In this specification, the thickness of a nonwoven fabric is the average value of the thickness measured about arbitrary multiple places (for example, 10 places) of a nonwoven fabric in a laminated nonwoven fabric, for example. The thickness of the nonwoven fabric refers to the distance between the two main surfaces of the nonwoven fabric. Specifically, the thickness of the nonwoven fabric is obtained by drawing a line perpendicular to one surface from any one point on one main surface of the nonwoven fabric to the other main surface in a cross-sectional photograph of the laminated nonwoven fabric. , Among the fibers on this line, it is determined as the distance between the outsides of the two most distant fibers. The thickness of the nonwoven fabric is measured in the same manner at other arbitrary plural points (for example, 9 points), and a value obtained by averaging these is set as the thickness of the nonwoven fabric. However, since the thickness of the nonwoven fabric is reduced in the region pressed by the convex portion of the embossed surface, the thickness of the nonwoven fabric is measured in a region other than the region pressed by the convex portion. In calculating the thickness of the non-woven fabric, a binarized image may be used. In this way, the thickness T1 of the first nonwoven fabric, the thickness T2 of the second nonwoven fabric described later, and the thickness T3 of the third nonwoven fabric can be determined.

From the viewpoint of reducing 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 or more and more preferably 60 g / ^{m 2} or less. In addition, the mass per unit area may be an average value of mass per unit area obtained for a predetermined area of a plurality of locations (for example, 10 locations) of the first nonwoven fabric.

(Second nonwoven fabric)
The second nonwoven fabric includes second fibers having an average fiber diameter D2 smaller than the average fiber diameter D1 of the first fibers, and has a function of capturing dust. The second nonwoven fabric is laminated on one main surface of the first nonwoven fabric.

  The average fiber diameter D2 is preferably 1/10 or less (D2 ≦ D1 / 10) of the average fiber diameter D1, and more preferably D2 ≦ D1 / 100. The average fiber diameter D2 is preferably 1/1000 or more (D1 / 1000 ≦ D2) of the average fiber diameter D1. When the average fiber diameter D2 is within this range, it is easy to further suppress the pressure loss, and it is easy to increase the dust collection efficiency. Specifically, the average fiber diameter D2 is preferably 30 nm to 3 μm or 30 nm to 1 μm. From the viewpoint of further improving dust collection efficiency while suppressing pressure loss, the second fiber is preferably a nanofiber. The average fiber diameter D2 of such second fibers is, for example, 30 to 800 nm, and preferably 50 to 800 nm.

  The material of the second fiber is not particularly limited. For example, PA, polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polyacetal (POM), polycarbonate (PC), polyetheretherketone (PEEK) , Polysulfone (PSF), polyethersulfone (PES), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyarylate (PAR), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinyl alcohol ( PVA), polyvinyl acetate (PVAc), PP, PET, polyurethane (PU), and other polymers. The polymer may be either a homopolymer or a copolymer. The second fibers may contain one or more of these materials. When the second fiber is formed by electrospinning, PES is preferably used. PVDF is preferably used from the viewpoint of easily reducing the average fiber diameter D2.

The molecular weight of the raw material resin for the second fiber is desirably larger than the molecular weight of the resin constituting the adhesive. In particular, when the second fiber raw resin and the resin constituting the adhesive are of the same type, the molecular weight of the raw resin is usually greater than the molecular weight of the resin constituting the adhesive. In Mw ₂ -Mw _a is preferably 10,000 or more, 20,000 or more, or 50,000: the difference between the weight average molecular weight Mw _a resin constituting the adhesive weight average molecular weight Mw ₂ of the raw material resin of the second fiber There may be.

  The method for producing the second nonwoven fabric is not particularly limited, and the second nonwoven fabric may be produced by the electrospinning method, although it may be produced by the method described for the first nonwoven fabric. When the second nonwoven fabric is formed by the electrospinning method, the second fibers are concentrated and deposited on the first fibers. Therefore, in addition to easily bonding non-woven fabrics, pressure loss can be further suppressed. Details of the production of the second nonwoven fabric by the electrospinning method will be described in more detail in the item of the method for producing a laminated nonwoven fabric described later.

  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 reducing the pressure loss as much as possible. 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 More preferably.
Even when the second nonwoven fabric is relatively thick (or has a large mass per unit area), adhesive particles having a small average particle size are attached to the second fibers, so that Peeling can be suppressed.

(Third nonwoven fabric)
The third nonwoven fabric has a function of collecting relatively large dust and functions as a protective material that protects the second nonwoven fabric from various external loads. A 3rd nonwoven fabric is laminated | stacked on the other main surface (main surface on the opposite side to a 1st nonwoven fabric) of a 2nd nonwoven fabric. From the viewpoint of dust collection efficiency, the third nonwoven fabric is preferably subjected to a charging treatment.

The material of the 3rd fiber contained in a 3rd nonwoven fabric is not specifically limited, It can select suitably from the material illustrated about the 1st 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, not less than 0.5 μm and not more than 20 μm, and not less than 1 μm and not more than 20 μm.

  The manufacturing method of a 3rd nonwoven fabric is not specifically limited, The method illustrated with the 1st nonwoven fabric can be illustrated similarly. Especially, it is preferable that a 3rd nonwoven fabric 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 thickness T3 of the third nonwoven fabric is not particularly limited, and may be 100 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 third nonwoven fabric is 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.

  Although the pressure loss of a 3rd nonwoven fabric is not specifically limited, It is preferable that the initial pressure loss of a 3rd nonwoven fabric is about 10 Pa or more and 50 Pa or less. If the initial pressure loss of the third nonwoven fabric is within this range, the pressure loss of the entire laminated nonwoven fabric is also suppressed.

(adhesive)
In the laminated nonwoven fabric, adhesive particles are attached to the second fibers, and the adhesive particles include first particles and second particles. The second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric are bonded via the first particles. The non-woven fabric is bonded to the non-woven fabric by point adhesion using the first particles in which the fibers are pressed to form a streak-like depression, and the fibers are not pressed to the second particles (or the second particles are crushed) The pressure loss of the laminated nonwoven fabric can be suppressed while suppressing peeling between the nonwoven fabrics.

  The adhesive particles may be adhered to the second fiber by spraying the powdered adhesive together with the dispersion medium onto the second fiber, but the adhesive may be adhered to the second fiber by an electrospinning method. preferable. If the adhesive is electrospun, the particle size of the adhesive particles can be reduced, and the adhesive can be finely and more uniformly dispersed. In addition, when the adhesive is electrospun, the adhesive particles tend to concentrate on the fiber. Therefore, the effect of suppressing the pressure loss can be further enhanced while ensuring the adhesive strength between the nonwoven fabrics.

  The adhesive may be subjected to electrospinning treatment of the adhesive solution, or may be subjected to electrospinning treatment (that is, electrospinning) together with the raw material resin of the second fiber. When the adhesive is electrospun together with the raw material resin of the second fiber, adhesive particles are formed and adhered to the second fiber when the second fiber is formed. Therefore, the adhesive particles are dispersed throughout the second nonwoven fabric, and the effect of suppressing the peeling between the second nonwoven fabric, the first nonwoven fabric, and the third nonwoven fabric is enhanced.

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

  When the adhesive is electrospun, adhesive particles are formed, and a thread-like body may be formed so as to pull the yarn from the adhesive particles. It is desirable that the filament is extremely fine and thinner than the second fiber. The average fiber diameter of the filamentous body 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 average mass of the adhesive attached to the laminated nonwoven 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 adhesiveness while reducing pressure loss. Is more 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 area to the total area s ₁ of the area pressed by the convex portion of the embossed surface: s ₂ / s ₁ is, for example, 1.1 to 10. 1.2-5 is preferable. Moreover, in a laminated nonwoven fabric, the average thickness of the area | region pressed by the convex part of the embossing surface of the 3rd nonwoven fabric is 50 to 95% of thickness T3 of the 3rd nonwoven fabric measured in area | regions other than this area | region, for example. Yes, it is preferably 60 to 80%. When the ratio s ₂ / s ₁ and / or the average thickness of the region pressed by the convex portion of the third nonwoven fabric is within such a range, the adhesive strength between the nonwoven fabrics can be easily increased while suppressing pressure loss.

  The laminated nonwoven fabric according to the present invention has high adhesive strength between the second nonwoven fabric, the first nonwoven fabric, and the third nonwoven fabric, and peeling is suppressed. In such a laminated nonwoven fabric, the peel strength between the second nonwoven fabric and each of the first nonwoven fabric and the third nonwoven fabric is, for example, 50 to 300 mN / 25 mm when measured by a method according to JISZ0237. .

(Method for producing laminated nonwoven fabric)
In the laminated nonwoven fabric, the first nonwoven fabric, the second nonwoven fabric, and the third nonwoven fabric are arranged in this order, and a part of the adhesive particles (specifically, the first particles) attached to the second fibers are interposed. Thus, the second nonwoven fabric can be produced by bonding the first nonwoven fabric and / or the third nonwoven fabric. It is preferable that the second fiber is made by spinning a raw material resin by an electrospinning process and deposited on the first nonwoven fabric, thereby laminating the second nonwoven fabric on the first nonwoven fabric. The adhesive particles are preferably formed by electrospinning a solution containing an adhesive. More preferably, the second fiber having the adhesive particles attached thereto is formed by electrospinning a solution containing the raw material resin of the second fiber and the adhesive.

In a preferred embodiment, the method for producing a laminated nonwoven fabric comprises:
A step (first step) of preparing a first nonwoven fabric containing first fibers, a raw material liquid containing a raw material resin and an adhesive serving as a raw material for the second fibers, and a third nonwoven fabric containing third fibers;
By electrospinning (electrospinning) method, a raw material liquid is discharged from a nozzle to generate second fibers having adhesive particles attached thereto, and second fibers having adhesive particles attached thereto are deposited on the first nonwoven fabric. A step of laminating the second non-woven fabric on one non-woven fabric (second step),
A step of placing a third nonwoven fabric containing third fibers on the main surface of the second nonwoven fabric opposite to the first nonwoven fabric to obtain a laminate (third step), and a pressure bonding comprising an embossed surface having a convex portion On the embossed surface of the member, the laminate is pressed in the thickness direction, and the second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric are crimped to obtain a laminated nonwoven fabric (fourth step). Prepare.

  In the crimping step, the fibers are pressed against a part of the adhesive particles by the convex portions of the embossed surface to form streak-like dents, thereby forming the first particles. At this time, the first particles may be crushed and spread. The remaining particles of the adhesive are present at positions opposite to the regions other than the convex portions of the embossed surface as second particles in which the streak-like depressions pressed against the fibers are not formed (or not crushed). To do. And the 2nd nonwoven fabric, the 1st nonwoven fabric, and / or the 3rd nonwoven fabric are pasted up via the 1st particle.

Hereinafter, each step will be described more specifically.
(First step)
In a 1st process, a 1st nonwoven fabric, said raw material liquid, and a 3rd nonwoven fabric are prepared.
The first nonwoven fabric and the third nonwoven fabric can be prepared by the method described above.

What was illustrated above is used as an adhesive agent contained in a raw material liquid. As raw material resin used as the raw material of the 2nd fiber, various polymers illustrated about the material of the 2nd fiber are used. Moreover, you may use the precursor of these polymers as raw material resin. For example, when the second fiber is composed of PI, a PI precursor such as polyamic acid may be used as the raw material resin.
The raw material liquid usually contains a solvent in addition to the second fiber raw material resin and the adhesive. An appropriate solvent may be selected according to the type of raw material resin and production conditions.

  As the solvent, water or an organic solvent is used. Examples of the organic solvent include alcohol, ether, ketone, ester, carboxylic acid (formic acid, acetic acid, etc.), nitrile (acetonitrile, etc.), amide, nitrogen-containing heterocyclic compound (pyridine, etc.), sulfoxide (dimethyl sulfoxide, etc.), phenol And hydrocarbons. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, hexafluoroisopropanol, tetraethylene glycol, triethylene glycol, and dibenzyl alcohol. As the ether, cyclic ethers such as 1,3-dioxolane, 1,4-dioxane and tetrahydrofuran 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, and cyclohexanone. Examples of esters include methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl benzoate, ethyl benzoate, propyl benzoate, dimethyl phthalate, diethyl phthalate, and dipropyl phthalate. . Examples of the amide include N, N-dimethylformamide and N, N-dimethylacetamide (DMAc). Examples of the hydrocarbon include hexane, cyclohexane, cyclopentane, benzene, toluene, xylene o-xylene, p-xylene, m-xylene and the like. The raw material liquid may contain one or more of these solvents. From the viewpoint of easily dissolving a raw material resin such as an adhesive or PES, an amide such as DMAc is preferable. Amides are 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 the adhesive and the raw material resin, when the second nonwoven fabric is deposited and the second nonwoven fabric is laminated, both the main surface facing the first nonwoven fabric and the main surface opposite to the first nonwoven fabric In addition, the adhesive is exposed. That is, since the adhesive is dispersed on both main surfaces of the second nonwoven fabric, the second nonwoven fabric, the first nonwoven fabric, and the second nonwoven fabric can be provided without a step of spraying the adhesive before and / or after the second nonwoven fabric is laminated. It becomes easy to raise the adhesive strength with 1 nonwoven fabric and 3rd nonwoven fabric. Therefore, the manufacturing process of the laminated nonwoven fabric can be simplified, and the space for the manufacturing apparatus can be saved.

  Moreover, when using the solution containing only an adhesive agent, there exists a tendency which is easy to gelatinize, but gelatinization of an adhesive agent can be suppressed because a raw material liquid contains an adhesive agent and raw material resin. The reason why gelation is suppressed is not clear, but it is considered that crystallization and aggregation of the adhesive are suppressed when the raw material liquid contains a raw material resin in addition to the adhesive.

  The raw material liquid may be prepared by mixing an adhesive and a first solution containing a first solvent that dissolves the adhesive and a second solution containing a raw material resin and a second solvent that dissolves the raw material resin. In this case, the time for the dissolution (preparation) step can be shortened, and a uniform solution can be produced. The first solution and the second solution are prepared in advance prior to the preparation of the raw material liquid. What is necessary is just to select a 1st solvent and a 2nd solvent suitably from the solvent illustrated above according to the kind of adhesive agent or raw material resin, respectively. The first solvent and the second solvent may be different. From the viewpoint of obtaining a uniform raw material liquid, the first solvent and the second solvent are preferably compatible with each other and may contain the same solvent. When the first solvent and the second solvent contain the same solvent, solution preparation and nozzle cleaning are also facilitated. Considering the ease of electrospinning and the like, it is preferable that each of the first solvent and the second solvent is an amide such as DMAc or an amide such as DMAc.

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

You may add a well-known additive, an antigelling agent, etc. to a raw material liquid as needed. 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 non-metals (B, Si, P, As, etc.) Etc.). From the viewpoint of workability and the like, it is preferable to use an oxide. Specific examples of the oxide include Al ₂ O ₃ , SiO ₂ , TiO ₂ , MgO, and CaO. An inorganic solid material may be used individually by 1 type, and may be used in combination of multiple types.

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

(Second step)
In the second step, the second fiber to which the adhesive particles are adhered is deposited on one main surface of the first nonwoven fabric by electrospinning, and the second nonwoven fabric is laminated. In electrospinning, a high voltage is applied to a raw material liquid, and the raw material liquid with an electric charge is discharged from a nozzle, A 2nd fiber produces | generates. At this time, the adhesive is also discharged from the nozzle and adheres to the second fiber.

  Since the adhesive has lower spinnability than the second fiber raw material resin, the adhesive is not in the form of a clean fiber like the second fiber, but in the form of particles. However, depending on the type of the adhesive, the thread of the adhesive connected to the adhesive particles is formed together with the adhesive particles by electrospinning. Since the adhesive has a lower spinnability than the raw material resin of the second fiber, the fiber diameter is extremely narrow compared to the second fiber even if a filamentous body is formed. As described above, when the raw material liquid is electrospun, the adhesive is dispersed throughout the second nonwoven fabric, so that the effect of suppressing separation between the second nonwoven fabric, the first nonwoven fabric, and the third nonwoven fabric is enhanced. The reason why the spinnability of the adhesive is lower than that of the raw material resin of the second fiber is not certain, but the difference in molecular weight between the adhesive (resin constituting the adhesive) and the raw material resin of the second fiber and the solvent. It is considered that the difference in solubility and / or the difference in interaction force between molecules influences.

  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, the spun fiber is suppressed from flying up, and is suitable for producing a relatively thin and homogeneous nonwoven fabric. The direction perpendicular to the surface direction of the first nonwoven fabric is not only a completely perpendicular direction 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). ).

  In the second step, if necessary, after a solution containing an adhesive is electrospun on one main surface of the first nonwoven fabric to adhere the adhesive particles, the second nonwoven fabric is laminated as described above. Also good. Further, after laminating the second nonwoven fabric on the first nonwoven fabric, the solution containing the adhesive is electrospun to adhere the adhesive particles to the main surface of the second nonwoven fabric opposite to the first nonwoven fabric. A third nonwoven fabric may be further laminated on the surface in the next step. 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, the solvent is removed in the process of forming the adhesive particles, so that it is not necessary to provide a separate solvent removal step.

(Third step)
In the third step, the third nonwoven fabric is further arranged on the second nonwoven fabric laminated on the first nonwoven fabric to obtain a laminate. The third nonwoven fabric is arranged so that one main surface of the third nonwoven fabric is in contact with the main surface of the second nonwoven fabric opposite to the first nonwoven fabric.

  In the third step, if necessary, the adhesive may be melted by heating before the third nonwoven fabric is disposed on the second nonwoven fabric. By melting the adhesive once in the third step, it is easy to place the third nonwoven fabric, and the adhesive is prevented from falling off. In particular, when a pressure-bonding member having an embossed surface is used in the fourth step described later, the adhesive particles (second particles) that are not pressed by the convex portions of the embossed surface are likely to drop off, but once bonded in the third step. By melting the agent, dropping of the adhesive is suppressed even in subsequent steps.

  The adhesive can be heated using, for example, a heater. The heating is preferably performed under the condition that the fibers (first fiber and second fiber) constituting the nonwoven fabric are not melted while melting the adhesive. Therefore, what is necessary is just to select heating temperature and heating time suitably according to the kind of adhesive agent, the material of a 1st fiber, and a 2nd fiber.

  When heating the adhesive in the third step, at least the second nonwoven fabric side may be heated, but when heating is performed so as to melt the entire adhesive contained in the laminate of the first nonwoven fabric and the second nonwoven fabric, It is effective in enhancing the adhesion between the nonwoven fabrics. You may heat so that the temperature of the main surface on the opposite side to the 1st nonwoven fabric of a 2nd nonwoven fabric may be 100-200 degreeC, for example, Preferably it is 120-170 degreeC.

(4th process)
In the fourth step (crimping step), the laminate obtained in the third step is pressed in the thickness direction on the embossed surface of the crimping member having an embossed surface having a convex portion, and the nonwoven fabrics are crimped together. When crimping is performed using the embossed surface of the crimping member, the convex portion of the embossed surface causes the fibers to be pressed against a part of the adhesive particles contained in the laminate to form a streak-like recess. Thus, the first particles are formed. And a 2nd nonwoven fabric, a 1st nonwoven fabric, and / or a 3rd nonwoven fabric are adhere | attached through this 1st particle | grain. The remaining adhesive particles are present as they are as the second particles in a position facing the region other than the convex portion of the embossed surface without forming a streak-like recess. In addition, in each 1st particle | grain, the state which at least one part of particle | grains was crushed may be sufficient, and the state which the whole particle | grain was crushed may be sufficient.

Since the particle size of the adhesive particles is small, even if it is difficult to bond the nonwoven fabrics by pressure bonding, the first particles are formed by embedding the fibers in a part of the adhesive particles by pressure bonding with a pressure-bonding member having an embossed surface. Formed, thereby ensuring adhesion between the nonwoven fabrics. On the other hand, if the pressure bonding is performed with a smooth pressure bonding member with a strong pressure, the nonwoven fabrics can be bonded to each other even if the particle size of the adhesive particles is small. However, when many adhesive particles are crushed and spread, the pressure loss of the laminated nonwoven fabric tends to increase. Therefore, from the viewpoint of suppressing pressure loss, the number n ₂ of the second particles is set to be larger than the number n ₁ of the first particles. In order to satisfy n ₂ > n ₁ , for example, the area of the other region may be larger than the area of the convex region on the embossed surface.

  The pressure bonding can be performed using a pressure bonding member such as a roller. In the fourth step, for example, the laminate is sandwiched between a pair of pressure rollers, and pressure is applied by the rollers to bond the second nonwoven fabric, the first nonwoven fabric, and the third nonwoven fabric via an adhesive. However, the main surface (in the case of a roller, the peripheral surface) that comes into contact with the laminate of the crimping members constitutes an embossed surface. Of the pair of rollers, the peripheral surface of one roller may be an embossed surface, and the peripheral surface of the other roller may be a smooth surface. Moreover, it is good also considering each peripheral surface of both rollers as a embossing surface among a pair of rollers.

  In the fourth step, the laminated nonwoven fabric can be obtained by crimping the laminate on the embossed surface of the crimping member. When the laminate is pressed by the crimping member in the fourth step in a state where the adhesive is melted in the third step, the second nonwoven fabric, the first nonwoven fabric and / or the third nonwoven fabric are interposed via the melted adhesive. Glued. In the fourth step, pressure bonding may be performed under heating as necessary. When the third nonwoven fabric is disposed without melting the adhesive in the third step, it is preferable to perform heating in the fourth step. When heating in the fourth step without melting the adhesive in the third step, the heater and the melting step for melting the adhesive can be omitted in the third step. Space can be saved.

  When pressure bonding is performed under heating, the heating temperature is, for example, 40 to 200 ° C. In the case of using a roller for pressure bonding, the pressure bonding can be performed under heating by using a heatable roller. Examples of the heatable roller include a roller having a built-in heater and a roller that can be heated from a connected heater.

  On the embossed surface, the shape and distribution of the protrusions are not particularly limited. For example, the convex portion may be a state where a plurality of point-like convex portions are dispersed, or a state where a plurality of linear or belt-like convex portions are arranged. The arrangement of the line-shaped or belt-shaped convex portions is not particularly limited, and may be, for example, a stripe shape or a zigzag shape. For example, a belt-like sheet may be wound around the peripheral surface of the roller to form a convex portion, or the convex portion may be formed by cutting the peripheral surface of the roller. The point-shaped convex portion may be, for example, a prismatic shape, a cylindrical shape, or an elliptical cylindrical shape. The convex portions 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 of the total area S ₂ of the other regions to the total area S ₁ of the convex regions on the embossed surface: S ₂ / S ₁ is, for example, It is 1.1-10, and it is preferable that it is 1.2-5.
Moreover, 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 a hardness required for pressure bonding, and for example, a known material used for a pressure-bonding member such as a resin, metal, or ceramic is used. The pressure-bonding member only needs to be formed of these materials at a portion that comes into contact with the laminated nonwoven fabric (in the roller, at least a circumferential surface or a convex portion on the embossed surface).

(Laminated nonwoven fabric manufacturing equipment)
The laminated nonwoven fabric is, for example, a production apparatus (or production system) that conveys the first nonwoven fabric from the upstream to the downstream of the production line, forms the second nonwoven fabric on the main surface of the conveyed first nonwoven fabric, and then laminates the third nonwoven fabric. ). Such a manufacturing apparatus contains, for example, (1) a first nonwoven fabric supply unit that supplies the first nonwoven fabric to the production line, and (2) a raw material liquid that contains a raw material resin and an adhesive that are raw materials for the second fibers. Tank, (3) by electrospinning the raw material liquid supplied from the tank, the second fiber is generated, the second fiber with the adhesive attached is deposited on the first nonwoven fabric, and the second nonwoven fabric is deposited on the first nonwoven fabric. An electrospinning mechanism to be laminated, (4) a third nonwoven fabric supply unit that supplies the third nonwoven fabric to the second nonwoven fabric, and (5) a crimping unit that crimps the second nonwoven fabric, the first nonwoven fabric, and the third nonwoven fabric.

  Hereinafter, although the manufacturing apparatus of a laminated nonwoven fabric is demonstrated, referring FIG. 2, the following manufacturing apparatuses do not limit this invention. FIG. 2 is a diagram schematically showing a configuration of an example of a manufacturing apparatus for the laminated nonwoven fabric 10. 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 1st nonwoven fabric 1 is conveyed downstream from the upstream of a manufacturing line. The most upstream of the manufacturing apparatus 200 is provided with a first nonwoven fabric supply unit 201 that houses therein the first nonwoven fabric 1 wound in a roller shape. The 1st nonwoven fabric supply part 201 rotates the supply reel 12 with the motor 13, and supplies the 1st nonwoven fabric 1 wound by the supply reel 12 to the conveyance roller 11 of a production line.

  The first nonwoven fabric 1 is transported by the transport roller 11 to an electrospinning apparatus 202 having an electrospinning unit (not shown). The electrospinning mechanism provided in the electrospinning unit includes an emitter 23 for discharging a raw material liquid containing a raw material resin and an adhesive for the second fiber, and a discharged raw material liquid. Charging means (see below) for charging the first non-woven fabric 1, and a transport conveyor 21 for transporting the first nonwoven fabric 1 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 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 fibers 2F formed may be changed for each electrospinning unit or each emitter 23 as necessary. good. The average fiber diameter of the second fibers 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 nonwoven fabric 1, the temperature, the humidity, and the like. be able to. The amount of deposition of the second fibers 2F is controlled by adjusting the discharge pressure of the raw material liquid, the applied voltage, the concentration of the raw material liquid, the conveyance speed of the first nonwoven fabric 1, and the like.

  On the side of the emitter 23 facing the main surface of the first nonwoven fabric 1, a plurality of outlets (not shown) for the raw material liquid are provided. Although the distance of the discharge port of the discharge body 23 and the 1st nonwoven fabric 1 is based also on the scale of a manufacturing apparatus and a desired fiber diameter, it should just be 100-600 mm, for example. The emitter 23 is installed above the electrospinning unit, and a second support 25 extending downward from the first support 24 parallel to the transport direction of the first nonwoven fabric 1 causes the longitudinal direction of the emitter 23 to be the first nonwoven fabric 1. It is supported so as to be parallel to the main surface. The first support 24 may be movable so that the emitter 23 is swung in a direction perpendicular to the conveying direction of the first nonwoven fabric 1.

  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 kV to 200 kV) corresponding 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 raw material liquid 22. The raw material liquid 22 is supplied from the raw material liquid 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 raw material liquid 22 is discharged from the discharge port toward the main surface of the first nonwoven fabric 1 by the pressure of the pump 28. The discharged raw material liquid 22 is electrostatically exploded while moving in the space (generation space) between the discharge body 23 and the first nonwoven fabric 1 in a charged state, and the fibrous material (second fiber 2F) is generated. Generate. At this time, adhesive particles (and adhesive filaments) are also generated and adhere 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 fibers 2F to which the adhesive particles (and the filaments) are attached is not limited to the above configuration. In a predetermined fiber generation space, the second fibers 2F and adhesive particles (and filaments) are generated from the raw material liquid 22 by electrostatic force, and the generated second fibers 2F and adhesive particles (and filaments) are Any mechanism that can be deposited on the main surface of the nonwoven fabric 1 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 whose cross-sectional shape perpendicular to the longitudinal direction of the emitter gradually decreases from the top to the bottom.

  Before the third nonwoven fabric 3 is laminated on the second nonwoven fabric 2, the adhesive may be melted by the heating device 204 including the heater 42. In the heating device 204, the solvent contained in the second nonwoven fabric 2 is also removed. 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 easily increasing the adhesive strength between the nonwoven fabrics, the adhesive particles are prevented from dropping in the subsequent process. 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 3rd nonwoven fabric lamination apparatus 205, the 3rd nonwoven fabric 3 is supplied to the main surface of the 2nd nonwoven fabric 2 from upper direction. When the 3rd nonwoven fabric 3 is elongate, the 3rd nonwoven fabric 3 may be wound up by the reel 52 similarly to the 1st nonwoven fabric 1. FIG. In this case, the third nonwoven fabric 3 is disposed on the main surface of the second nonwoven fabric 2 while being rolled out from the reel 52.

  After arrange | positioning the 3rd nonwoven fabric 3 to the main surface of the 2nd nonwoven fabric 2, it presses with a crimping | compression-bonding part provided with a pair of pressurizing rollers 53 (53a and 53b) arrange | positioned up and down on both sides of the obtained laminate. At least one peripheral surface of the pressure rollers 53a and 53b constitutes an embossed surface provided with a convex portion. Therefore, the fibers are pressed (or embedded) on some of the adhesive particles by the convex portions 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 thread of the adhesive) to form the laminated non-woven fabric 10.

  Finally, the laminated nonwoven fabric 10 is carried out from the third nonwoven fabric laminating device 205 and is conveyed via the roller 61 to the collecting device 206 arranged further downstream. The collection device 206 includes, for example, a collection reel 62 that scrapes off the laminated nonwoven fabric 10 being conveyed. The collection reel 62 is rotationally driven by a motor 63.

  Before forming the 2nd nonwoven fabric 2, you may convey the 1st nonwoven fabric 1 to an adhesive agent dispersion apparatus as needed. In the adhesive spraying device, the adhesive is sprayed from above the first nonwoven fabric 1. The adhesive may be sprayed by, for example, spraying, free fall, etc., but 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. Also good. Similarly, after forming the 2nd nonwoven fabric 2, you may convey the 2nd nonwoven fabric 2 laminated | stacked on the 1st nonwoven fabric 1 to the adhesive agent dispersion apparatus as needed. In addition, when a plurality of electrospinning apparatuses 202 are provided, an adhesive spraying apparatus may be provided between the plurality of electrospinning apparatuses 202.

  FIG. 3 is a schematic diagram illustrating another configuration example of a laminated nonwoven fabric manufacturing apparatus. The manufacturing apparatus of FIG. 3 includes an adhesive spraying device 203 before and after the electrospinning device 202 in addition to the configuration of FIG. The adhesive spraying device 203 may be provided either before or after the electrospinning device 202. The adhesive spraying device 203 sprays the adhesive 4 using the adhesive solution 32 by the electrospinning method based on the same principle as the electrospinning device 202. In addition, you may add a well-known additive, an antigelling agent, etc. to an adhesive solution.

  The first nonwoven fabric 1 is transported to the adhesive spraying device 203 by the transport roller 11. The electrospinning mechanism provided in the adhesive spraying device 203 includes an emitter 33 for releasing an adhesive solution 32 containing an adhesive and a solvent installed in the upper portion of the device, and the released adhesive solution 32 as a plus. A charging means for charging and a transport conveyor 31 that is disposed so as to face the emitter 33 and transport the first nonwoven fabric 1 from the upstream side to the downstream side are provided. The number of emitters 33 is not particularly limited, and may be one or two or more. On the side of the emitter 33 facing the main surface of the first nonwoven fabric 1, a plurality of adhesive solution outlets (not shown) are provided. The discharge body 33 is disposed on the upper side, and the second support body 35 extending downward from the first support body 34 parallel to the conveying direction of the first nonwoven fabric 1 causes the longitudinal direction of the discharge body 33 to be the main surface of the first nonwoven fabric 1. It is supported to be parallel. The first support 34 may be movable so that the emitter 33 is swung in a direction perpendicular to the conveying direction of the first nonwoven fabric 1.

  The charging means includes a voltage applying device 36 that applies a voltage to the emitter 33 and a counter electrode 37 that is installed in parallel with the conveyor 31. The counter electrode 37 is grounded. Instead of providing the counter electrode 37, the belt portion of the transport conveyor 31 may be formed of a conductor. The emitter 33 is made of a conductor, has a long shape, and its inside is hollow. The hollow portion serves as a storage portion that stores the adhesive solution 32. The adhesive solution 32 is supplied from the adhesive solution tank 39 to the middle part 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 discharge port 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 (generation space) between the emitter 33 and the first nonwoven fabric 1 in a charged state. At this time, a thread-like body of the adhesive 4 may be formed. The generated particles of the adhesive 4 (and the filaments of the adhesive 4) adhere to the main surface of the first nonwoven fabric.

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

  When the size of the adhesive particles is small and the peripheral surface of the pressure roller (crimp member) of the crimping part is a smooth surface, it may be difficult to increase the adhesive strength. In addition, pressure loss tends to increase when pressure bonding is performed at a high pressure to increase the adhesive strength. In such a case, by using a pressure-bonding member having an embossed surface, the adhesive strength between the nonwoven fabrics can be further increased while suppressing pressure loss. In the case of a pressure roller, an embossed surface may be provided on the peripheral surface. Of the pair of pressure rollers, an embossed surface may be provided on one roller, or an embossed surface may be provided on both rollers.

  FIG. 4 and FIG. 5 are schematic diagrams for explaining pressure bonding using a pressure roller having an embossed surface on the peripheral surface. In FIG. 4, one roller 153a of the pair of pressure rollers has an embossed surface in which a plurality of convex portions 154 are formed on the peripheral surface, and the peripheral surface of the other roller 153b is a smooth surface. Yes. FIG. 4 shows an example in which the upper roller 153a has an embossed surface. However, the present invention is not limited to this, and the embossed surface may be provided only on the lower roller. FIG. 5 shows an example in which embossed surfaces are arranged on both peripheral surfaces of the pair of rollers 253a and 253b. Each embossed surface of the rollers 253a and 253b has a plurality of convex portions 254.

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

(Air cleaner)
The laminated nonwoven fabric according to the present invention is particularly suitable for use as a filter medium for an air cleaner. An air cleaner provided with a laminated nonwoven fabric is illustrated in FIG. The air purifier 100 includes a gas suction part 101, a gas discharge part 102, and a laminated nonwoven fabric 10 disposed between the gas suction part 101 and the discharge part 102. The laminated nonwoven fabric 10 may be arranged by being pleated into a bellows shape. The laminated nonwoven fabric 10 is a filter medium that captures dust in the atmosphere. The air cleaner provided with the laminated nonwoven fabric 10 has a small pressure loss and excellent 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 so that the second nonwoven fabric 3 is positioned on the suction portion 101 side.

  The air cleaner 100 takes in external air from the suction unit 101 into the air cleaner 100. 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 unit 102 to the outside. The air cleaner 100 may further include a prefilter 103 that captures large dust or the like between the suction portion 101 and the laminated nonwoven fabric 10. Moreover, the deodorizing filter 104, a humidification filter (not shown), etc. may be provided between the laminated nonwoven fabric 10 and the discharge part 102. FIG.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
A laminated nonwoven fabric was produced by the following procedure.
First, a first nonwoven fabric (thickness: 300 μm, D1: 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 laminated by depositing the second fibers to which the adhesive particles and the thread of the adhesive had adhered to the first non-woven fabric to be conveyed. The raw material liquid for the second fibers includes 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 prepared by mixing (second solution) at a mass ratio of 1: 1 was used. The average fiber diameter D2 of the obtained second fibers was 273 nm, and the average mass per unit area was 0.93 g / m ² .

  An SEM photograph taken from the second nonwoven fabric side is shown in FIG. As shown in FIG. 7, adhesive particles are attached to the second fibers, and an adhesive thread formed so as to pull the thread can also be observed.

Next, after heating from the second nonwoven fabric side so that the surface of the second nonwoven fabric is 158 ° C., a melt blown nonwoven fabric mainly composed of polypropylene fibers as the third nonwoven fabric from the second nonwoven fabric side (thickness: 165 μm, D3: 5 μm, unit The 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 obtain a laminated nonwoven fabric. As one of the pair of pressure rollers, a roller having an embossed surface having a plurality of convex portions (a cylindrical shape with a diameter of 5 mm × a height of 1 mm and a distance of 10 mm between adjacent convex portions) on the peripheral surface was used. The pressure for pressure bonding was 10 kPa.

  A 30 cm square sample was cut from the resulting laminated nonwoven fabric and folded into a pleated shape (pleated width: 2.5 cm). Subsequently, when the laminated nonwoven fabric was spread and the surface on the third nonwoven fabric side was confirmed with a microscope, lifting (peeling) of the third nonwoven fabric was not confirmed. The thickness T2 of the second nonwoven fabric in the laminated nonwoven fabric (average thickness of the second nonwoven fabric in the region other than the region pressed by the convex portion) was 2.3 μm.

  Separately, a sample having a width of 25 mm and a length of 200 mm was cut from the laminated nonwoven fabric. The peel strength between the first nonwoven fabric and the third nonwoven fabric of the sample was measured by a method based on JISZ0237. The peel strength was 88 mN / 25 mm.

The laminated nonwoven fabric was cut into 12 cm × 12 cm, and dust in the atmosphere was sucked into the obtained sample at a surface wind speed of 5.3 cm / sec (suction test). When the air pressure P ₀ on the upstream side and the air pressure P ₁ on the downstream side of the sample were measured and the pressure loss (= P ₀ −P ₁ ) was calculated, it was 48 Pa. In addition, the measuring machine (manometer) based on the standard of JISB9908 was used for the measurement of air pressure.

FIG. 8 is an SEM photograph taken from the second nonwoven fabric side after peeling the third nonwoven fabric from the laminated nonwoven fabric. In the area on the left side of the photo, the small adhesive particles maintain a spherical shape (second particle), whereas in the area on the right side, the adhesive particles are crushed and spread with fibers embedded. A streak-like depression is formed, and the adhesive particles and the fibers are in a bonded state (first particles). The part where the fiber is embedded in the adhesive particle corresponds to the convex part of the embossed surface of the pressure roller, and the part where the spherical shape of the adhesive particle is maintained corresponds to the area other than the convex part. ing. 2. The number n ₁ of the first particles and the number n ₂ of the second particles were measured for an arbitrarily selected region of 10 mm long × 10 mm wide in the SEM photograph, and the n ₂ / n ₁ ratio was determined. 4.

(Reference Example 1)
A laminated nonwoven 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 crimping member.
A 30 cm square sample was cut from the resulting laminated nonwoven fabric. Similar to Example 1, the obtained sample was folded into a pleat shape and then spread, and the surface on the third nonwoven fabric side was confirmed with a microscope, but the lifting (peeling) of the third nonwoven fabric was not confirmed. Separately, when peel strength and pressure loss were measured by the same method as in Example 1, they were 210 mN / 25 mm and 72 Pa, respectively. The third nonwoven fabric was peeled from the laminated nonwoven fabric, an SEM photograph was taken from the second nonwoven fabric side, and when the adhesive particles were observed in the SEM photograph, almost all of the adhesive particles were the first particles.

(Reference Example 2)
A laminated nonwoven 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 for pressure bonding was changed to 1 kPa.
A 30 cm square sample was cut from the resulting laminated nonwoven fabric. In the same manner as in Example 1, the obtained sample was folded into a pleat shape and then spread, and when the surface of the third nonwoven fabric side was checked with a microscope, lifting (peeling) of the third nonwoven fabric was confirmed. Separately, when peel strength and pressure loss were measured by the same method as in Example 1, they were 19 mN / 25 mm and 46 Pa, respectively. The third nonwoven fabric was peeled off from the laminated nonwoven fabric, an SEM photograph was taken from the second nonwoven fabric side, and when the adhesive particles were observed in the SEM photograph, almost all of the adhesive particles were the second particles.

  The laminated nonwoven fabric of the present invention is useful as a filter medium for an air cleaner or an air conditioner because pressure loss and separation between the nonwoven fabrics are suppressed. In addition, laminated nonwoven fabrics include separation sheets for batteries, membranes for fuel cells, in vitro inspection sheets such as pregnancy test sheets, medical sheets for cell culture, dustproof cloths such as dust masks and dustproof clothes, cosmetic sheets, It can also be used as a wiping sheet for wiping off dust.

1: 1st nonwoven fabric, 2F: 2nd fiber, 2: 2nd nonwoven fabric, 3: 3rd nonwoven fabric, 10: Laminated nonwoven fabric, 11: Conveying roller, 12: Supply reel, 13: Motor, 21, 31: Conveying 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: Embossed surface convex part, 61: Roller, 62: Collection reel, 63: Motor, 100: Air cleaner, 101: Suction part, 102: Discharge part, 103: Pre-fill 104: Deodorizing filter, 200: Manufacturing device (manufacturing system), 201: First nonwoven fabric supply unit, 202: Electrospinning device, 203: Adhesive spraying device, 204: Heating device, 205: Third nonwoven fabric laminating device 206: Collection device

Claims (8)

A first nonwoven including first fibers;
A second nonwoven fabric laminated on the first nonwoven fabric and containing second fibers;
A third nonwoven fabric laminated on the main surface of the second nonwoven fabric opposite to the first nonwoven fabric and containing third fibers;
An adhesive, and
The adhesive particles are attached to the second fibers,
The adhesive particles include first particles having streak-like depressions and other second particles.
The number n ₂ of the second particles is larger than the number n _{1 of} the first particles,
A laminated nonwoven fabric in which the second nonwoven fabric is bonded to the first nonwoven fabric and / or the third nonwoven fabric via the first particles. 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, layered nonwoven fabric of claim 1.   The laminated nonwoven fabric according to claim 1 or 2, wherein the second fibers are nanofibers. The average fiber diameter D1 of the first fibers and the average fiber diameter D2 of the second fibers satisfy the relationship D1> D2,
The laminated nonwoven fabric according to any one of claims 1 to 3, wherein an average particle diameter Dp of the second particles and an average fiber diameter D1 of the first fibers satisfy a relationship of D1> Dp.   The laminated nonwoven fabric according to claim 4, wherein the average particle diameter Dp of the second particles and the average fiber diameter D2 of the second fibers satisfy a relationship of Dp> D2.   The laminated nonwoven fabric according to claim 4 or 5, wherein an average particle diameter Dp of the second particles is 1 to 200 µm. The laminated nonwoven fabric further includes a thread of the adhesive,
The laminated nonwoven fabric according to any one of claims 1 to 6, wherein the filamentous body is connected to particles of the adhesive. A step of preparing a first nonwoven fabric containing first fibers, a raw material liquid containing a raw material resin and an adhesive as raw materials for the second fibers, and a third nonwoven fabric containing third fibers;
By electrospinning, the raw material liquid is discharged from a nozzle to generate second fibers having the adhesive particles attached thereto, and the second fibers having the adhesive particles attached thereto are deposited on the first nonwoven fabric. Laminating a second nonwoven fabric to the first nonwoven fabric;
A step of obtaining a laminate by disposing a third nonwoven fabric containing third fibers on the main surface of the second nonwoven fabric opposite to the first nonwoven fabric;
Pressing the laminate in the thickness direction on the embossed surface of the pressure-bonding member having an embossed surface having a convex portion, and crimping the second nonwoven fabric and the first nonwoven fabric and / or the third nonwoven fabric. A crimping step for obtaining a laminated nonwoven fabric,
In the crimping step, 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 adhesive particles by the convex portion of the embossed surface. The first particles in which the streak-like dents are formed are formed, and the remaining particles of the adhesive are not formed in the streak-like dents, and the convex portions of the embossed surface are formed as second particles. The second non-woven fabric, the first non-woven fabric and / or the third non-woven fabric are bonded via the first particles, and the number n ₂ of the second particles is The method for producing a laminated nonwoven fabric, which is greater than the number n ₁ of the first particles.