JP6590312B2 - Laminated nonwoven fabric and air purifier, and method for producing laminated nonwoven fabric - Google Patents

Description

  The present invention relates to a laminated nonwoven fabric, for example, a laminated nonwoven fabric used for a filter medium of an air cleaner.

  A non-woven fabric (second non-woven fabric) that has a smaller average fiber diameter than the non-woven fabric (first non-woven fabric) that functions as a base material as a filter medium used in an air cleaner and the like, and that protects the non-woven fabric (second non-woven fabric) In addition, it has been proposed to use a laminated nonwoven fabric in which another nonwoven fabric (third nonwoven fabric) having a dust collecting function is laminated (Patent Document 1).

International Publication No. 2013/121733 Pamphlet

  However, when the laminated nonwoven fabric of Patent Document 1 is formed into a pleated shape, the second nonwoven fabric and the third nonwoven fabric may peel from the first nonwoven fabric. When the second nonwoven fabric and the third nonwoven fabric are peeled off, the dust collection efficiency is remarkably lowered when the laminated nonwoven fabric is used as a filter medium.

One aspect of the present invention includes a first nonwoven fabric comprising a first fiber, the first laminated to the nonwoven, and a second nonwoven fabric comprising a second fibers, the main surface side which does not face the first nonwoven fabric the second nonwoven fabric And a third nonwoven fabric containing third fibers, and an adhesive interspersed between the first nonwoven fabric and the third nonwoven fabric, and an average fiber diameter D2 of the second fibers. Is 3 μm or less, the average fiber diameter D1 of the first fibers and the average fiber diameter D2 satisfy a relationship of D1> D2, and the adhesive forms a plurality of dot regions, and the dot regions but wherein the first dots formed by a single particle of the adhesive, the second dots formed by the fusion adherend two or more particles of the adhesive, only including, the main of the second nonwoven fabric The second nonwoven of the second dots when viewed from a cross-section perpendicular to the surface The height from the third nonwoven side of the surface, larger than the height from said second nonwoven third nonwoven side of the surface of the first dot, a laminated nonwoven fabric.

Another aspect of the present invention is the first non-woven fabric including the first fiber and the second fiber, the third non-woven fabric laminated on the first non-woven fabric and including the third fiber, the first non-woven fabric, and the third non-woven fabric. An average fiber diameter D2 of the second fibers of 3 μm or less, and an average fiber diameter D1 of the first fibers and the average fiber diameter D2 of D1>. A composite comprising the first fiber and the second fiber, wherein the first a-nonwoven fabric satisfies the relationship of D2, and the base layer containing the first fiber and the main surface facing the third nonwoven fabric are disposed. A first dot formed by a single particle of the adhesive, and two or more particles of the adhesive, wherein the adhesive forms a plurality of dot regions look including a second dots formed by fusion of said 1a When viewed from a cross section perpendicular to the main surface of the woven fabric facing the third nonwoven fabric, the height of the second dot from the surface of the composite layer on the third nonwoven fabric side is the first dot. It is related with the laminated nonwoven fabric which is larger than the height from the surface by the side of the said 3rd nonwoven fabric of the said composite layer .

  Still another aspect of the present invention relates to an air cleaner comprising: a gas suction part; the gas discharge part; and the laminated nonwoven fabric disposed between the suction part and the discharge part. .

Still another aspect of the present invention provides a first preparation step of preparing a first nonwoven fabric containing first fibers, and a raw material liquid containing a raw material resin as a raw material of the second fibers and a solvent for dissolving the raw material resin. A second preparatory step, a third preparatory step of preparing a third nonwoven fabric containing third fibers, and spraying the raw material liquid on the first non-woven fabric to generate second fibers from the raw material liquid, A non-woven fabric forming step for depositing the second fibers on one main surface of the first non-woven fabric, and an adhesive spraying step for spraying adhesive particles on the main surface of the first non-woven fabric on which the second fibers are deposited. And a heating step for melting the adhesive spread on the main surface, a laminating step for laminating the third nonwoven fabric via the second fibers on the first nonwoven fabric having the melted adhesive, comprising a scattering amount of the adhesive is from 5 g / m ² Can rather, an average particle diameter of the adhesive, 150 [mu] m or more and less than 200 [mu] m, a method of manufacturing a laminated nonwoven fabric.

  According to the present invention, peeling between nonwoven fabrics can be suppressed in a laminated nonwoven fabric.

It is the top view (a) and sectional view (b) which show typically the principal part of the lamination nonwoven fabric concerning one embodiment of the present invention. It is a figure which shows the structural example of the manufacturing system used for manufacture of the laminated nonwoven fabric which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the principal part of the laminated nonwoven fabric which concerns on other one Embodiment of this invention. It is a perspective view showing typically an air cleaner concerning one embodiment of the present invention. 2 is a photomicrograph of the surface on the second nonwoven fabric side according to Example 1. FIG. 4 is a photomicrograph of the surface on the second nonwoven fabric side according to Comparative Example 1.

(First embodiment)
The laminated nonwoven fabric according to the present embodiment includes a first nonwoven fabric containing first fibers, a second nonwoven fabric laminated on the first nonwoven fabric and containing second fibers, and a main surface 2A side that does not face the first nonwoven fabric of the second nonwoven fabric. And a third nonwoven fabric including third fibers and an adhesive interspersed between the first nonwoven fabric and the third nonwoven fabric. Hereinafter, the laminated nonwoven fabric will be specifically described as a form suitable for the filter medium of the air cleaner, but the use of the laminated nonwoven fabric is not limited thereto.

  The first nonwoven fabric functions as a base material that maintains the shape of the laminated nonwoven fabric. When the laminated nonwoven fabric is pleated, the first nonwoven fabric serves as a base material and maintains the shape of the pleats.

  The first nonwoven fabric includes the first fibers 1F. The material of the first fiber 1F is not particularly limited. For example, glass fiber, cellulose, acrylic resin, polypropylene (PP), polyethylene (PE), polyester (for example, polyethylene terephthalate (PET), polybutylene terephthalate), polyamide (PA ), Or a mixture thereof. Among these, from the viewpoint of shape retention, the material of the first fiber 1F is preferably PET or cellulose. The average fiber diameter D1 of the first fibers 1F is not particularly limited, and may be, for example, 1 μm or more and 40 μm or less, or 5 μm or more and 20 μm or less.

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

  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 the 1st nonwoven fabric 1 is manufactured by the wet method at the point in 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. Especially, when the initial pressure loss of a 1st nonwoven fabric is measured using the measuring machine based on the standard of JISB9908 format 1, it is preferable that it is about 1 Pa or more and 10 Pa or less. 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.

  From the viewpoint of pressure loss, 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. The thickness T of the nonwoven fabric is, for example, an average value of the thicknesses of arbitrary 10 locations of the nonwoven fabric (hereinafter the same). The thickness is a distance between the two main surfaces of the nonwoven fabric. Specifically, the thickness T of the nonwoven fabric is taken by taking a photograph of a cross section of the nonwoven fabric, and a line perpendicular to one surface is drawn from any one point on one principal surface of the nonwoven fabric to the other principal surface. It is calculated | required as the distance of the outer side (outside method) of two fibers in the most distant position among the fibers on this line. The thickness of the non-woven fabric is calculated in the same manner for other arbitrary plural points (for example, 9 points), and a value obtained by averaging these is defined as the thickness T of the non-woven fabric. In calculating the thickness T, a binarized image may be used.

From the same viewpoint, 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, more preferably 35 g / m ² or more and 60 g / m ² or less. .

  The second nonwoven fabric includes the second fibers 2F having an average fiber diameter D2 smaller than the average fiber diameter D1 of the first fibers 1F, and has a function of capturing dust. 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 / 10. Moreover, it is preferable that the average fiber diameter D2 is 1/100 or more of the average fiber diameter D1. If the average fiber diameter D2 is within this range, the pressure loss is suppressed and the dust collection efficiency tends to be high. Specifically, the average fiber diameter D2 is 3 μm or less. The average fiber diameter D2 is preferably 1 μm or less, and more preferably 300 nm or less. The average fiber diameter D2 is preferably 30 nm or more, and more preferably 50 nm or more.

Mass per unit area of the second nonwoven fabric, 0.01 g / m ² or more, is preferably 1.5 g / m ² or less, 0.01 g / m ² or more and 0.5 g / m ² or less Is more preferably 0.03 g / m ² or more and 0.1 g / m ² or less. When the mass of the second nonwoven fabric is within this range, high dust collection efficiency is easily exhibited while suppressing pressure loss.

  The material of the second fiber 2F 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. You may use these individually or in combination of 2 or more types. Especially, when forming the 2nd fiber 2F by an electrospinning method, PES is used preferably. Moreover, PVDF is preferably used in that the average fiber diameter can be easily reduced.

  From the viewpoint of pressure loss, the thickness T2 of the second nonwoven fabric is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less. In addition, when the initial pressure loss of the 2nd nonwoven fabric 2 is measured on the conditions similar to the above, it is preferable that it is about 5 Pa or more and 40 Pa or less.

  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. From the viewpoint of dust collection efficiency, the third nonwoven fabric 3 is preferably subjected to a charging treatment.

  The third nonwoven fabric includes the third fibers 3F. The material of the 3rd fiber 3F is not specifically limited, The same material as a 1st nonwoven fabric can be illustrated. Among these, PP is preferable because it is easily charged. The average fiber diameter D3 of the third fibers 3F is not particularly limited. The average fiber diameter D3 is, for example, 0.5 μm or more and 20 μm or less, and 5 μm or more and 20 μm or less.

  The manufacturing method of the 3rd nonwoven fabric 3 is not specifically limited, The method illustrated with the 1st nonwoven fabric 1 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 pressure loss of the third nonwoven fabric is not particularly limited. Especially, when the initial pressure loss of a 3rd nonwoven fabric is measured on the conditions similar to the above, it is preferable that it 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.

The thickness T3 of the third nonwoven fabric is preferably 100 μm or more and 500 μm or less, more preferably 150 μm or more and 400 μm or less from the viewpoint of pressure loss. Mass per unit area of the third nonwoven, from the viewpoint of pressure loss, 10 g / m ² or more, preferably 50 g / m ² or less, 10 g / m ² or more, more not less 30 g / m ² or less preferable.

  The second nonwoven fabric and the third nonwoven fabric are bonded using adhesive particles. For example, after spraying a particulate thermoplastic resin as an adhesive on the second nonwoven fabric side of the laminate of the first nonwoven fabric and the second nonwoven fabric and melting them, the third nonwoven fabric is laminated.

  On the other hand, the first nonwoven fabric and the second nonwoven fabric are laminated without using an adhesive. The second nonwoven fabric is formed on the first nonwoven fabric by, for example, an electrospinning method. In the electrospinning method, a high voltage is applied to a raw material liquid in which a resin (raw material resin) that is a raw material of the second fiber constituting the second nonwoven fabric is dissolved, and a charged raw material liquid is ejected from a nozzle. Thus, the second fiber is formed. The second fibers are deposited on the first nonwoven fabric in a state containing a solvent to form a second nonwoven fabric. At this time, the second fiber containing the solvent is brought into close contact with the first fiber constituting the first nonwoven fabric, so that both are joined.

  In the above case, the first non-woven fabric and the second non-woven fabric are bonded by point bonding between fibers. Therefore, peeling is likely to occur between the first nonwoven fabric and the second nonwoven fabric, and when the third nonwoven fabric peels, the second nonwoven fabric adhered to the third nonwoven fabric via an adhesive is the second nonwoven fabric together with the third nonwoven fabric. 1 It will peel from a nonwoven fabric. When the second nonwoven fabric and the third nonwoven fabric are peeled off, the dust collection efficiency is remarkably lowered when the laminated nonwoven fabric is used as a filter medium.

  Since the adhesive is in the form of particles, if the adhesive is not sufficiently melted, the proportion of the adhesive that does not contribute to dropping off from the laminated nonwoven fabric or adhesion between the second nonwoven fabric and the third nonwoven fabric increases. Therefore, in order to suppress peeling of the third nonwoven fabric, it is conceivable to sufficiently melt the adhesive. However, if the heating conditions are severed in order to sufficiently melt the adhesive, the pressure loss of the obtained laminated nonwoven fabric becomes very large. Even when each nonwoven fabric is crimped under heating without spraying the adhesive, the pressure loss increases, so the main factor that increases the pressure loss of the laminated nonwoven fabric is the heat for melting the adhesive. Therefore, it is considered that the second fibers having a small average fiber diameter are deformed and the voids of the second nonwoven fabric and the third nonwoven fabric are reduced. Therefore, in the present invention, the third nonwoven fabric is prevented from peeling off by forming a fused body containing two or more adhesive particles on the second nonwoven fabric side of the laminate.

By the way, conventionally, one of the factors that increase the pressure loss is considered to be an adhesive. For this reason, the adhesive is generally sprayed with an upper limit of about 2 g / m ² . However, it is difficult to form a fused body with such an application amount. On the other hand, even if the amount of adhesive sprayed is increased to such an extent that a fused body can be formed, the pressure loss does not increase greatly.

  That is, the laminated nonwoven fabric according to the present invention includes a first nonwoven fabric containing first fibers, a second nonwoven fabric laminated on the first nonwoven fabric and containing second fibers, and a main surface 2A that does not face the first nonwoven fabric of the second nonwoven fabric. And a third nonwoven fabric including the third fibers and an adhesive interspersed between the first nonwoven fabric and the third nonwoven fabric, the average fiber diameter D1 of the first fibers and the first fibers The average fiber diameter D2 of the two fibers satisfies the relationship D1> D2. At this time, the adhesive forms a plurality of dot regions, and the dot regions are formed by a first dot formed by a single particle of the adhesive and a fusion product of two or more particles of the adhesive. Second dots. Thereby, peeling of a 3rd nonwoven fabric and also a 2nd nonwoven fabric is suppressed, without increasing a pressure loss.

  Hereinafter, the laminated nonwoven fabric according to the present invention will be described with reference to FIG. Fig.1 (a) is a top view which shows typically the principal part of laminated nonwoven fabric 10A which concerns on this embodiment, FIG.1 (b) is sectional drawing in the BB line of Fig.1 (a). .

  The adhesive 4 interspersed between the first nonwoven fabric 1 and the third nonwoven fabric 3 forms a plurality of dot regions. In other words, the shape of the adhesive 4 viewed from the main surface of the second nonwoven fabric 2 that does not face the first nonwoven fabric 1 is a dot shape. At least a part of the dot region is a fused body formed by fusing two or more adhesive particles. That is, the dot area formed by the adhesive 4 includes a first dot A1 formed by a single particle of the adhesive, a second dot A2 formed by a fusion body of two or more particles of the adhesive, including.

  The maximum diameter and the area S2 per one of the second dots A2 which are fusion bodies of a plurality of particles are the maximum as viewed from the main surface of the first dots A1 formed from a single particle. It is larger than the diameter and the area S1 per one. Therefore, the laminated body of the 1st nonwoven fabric 1 and the 2nd nonwoven fabric 2, and the 3rd nonwoven fabric 3 are adhere | attached by a larger area by 2nd dot A2. Further, the height H2 of the second dot A2 viewed from the cross section perpendicular to the main surface is greater than the height H1 of the first dot A1 viewed from the cross section. That is, the adhesive particles penetrate not only to the surfaces of the third nonwoven fabric 3 and the laminate, but also to the inside thereof, thereby bonding the third nonwoven fabric 3 and the laminate. Therefore, the third nonwoven fabric 3 is hardly peeled off.

  Here, it is also conceivable to form a dot region having a diameter corresponding to the maximum diameter and height of the second dot A2 with particles of a single adhesive. In this case, adhesive particles having a larger particle diameter than that used to form the second dots A2 may be used. However, a larger amount of heat is required to melt the large adhesive particles. Therefore, when the heating conditions are strict, as described above, the second fibers 2F are deformed, resulting in an increase in pressure loss. If the adhesive is not sufficiently melted, it will fall off the laminated nonwoven fabric. That is, by using adhesive particles having a relatively small particle size and fusing them on the laminate, deformation of the second fibers 2F and an increase in pressure loss due to heat are suppressed, and the adhesive strength is increased. be able to.

  The average particle diameter of the adhesive particles used for forming the first dots and the second dots is preferably 150 to 350 μm, and more preferably 180 to 300 μm. When the average particle diameter of the adhesive is within this range, melting under a heating condition that does not cause deformation of the second fibers 2F is possible, and the second dots A2 are easily formed. The average particle diameter is a median diameter (D50) in a volume particle size distribution determined by a laser diffraction particle size distribution measuring apparatus (hereinafter the same).

  The kind of particle | grains of an adhesive agent is not specifically limited, For example, the hot-melt-adhesive etc. which have a thermoplastic resin as a main component are mentioned. Examples of the thermoplastic resin include polyesters such as PU and PET, copolymer polyesters such as urethane-modified copolymer polyester, PA, and polyolefins (for example, PP and PE). The melting point of the adhesive is preferably about 60 to 140 ° C.

  The second dots A2 are formed, for example, by fusing 2 or more and 10 or less adhesive particles, and are usually indefinite. At this time, the adhesive particles may be fused to such an extent that the interface can be confirmed, or the interface may not be confirmed.

The area S2 per second dot A2 is not particularly limited, and is determined according to the degree of particle overlap and the particle size. The area S2 is, for example, 1.3 times or more the area S1 per one first dot A1. The area S1 is, for example, 0.02 to 0.20 mm ² , and preferably 0.03 to 0.10 mm ² .

  The maximum diameter of the second dot A2 is, for example, 200 μm or more, and preferably 300 μm or more. The diameter of 1st dot A1 is 50-500 micrometers, for example, Preferably it is 1500-300 micrometers. The diameter of the first dot A1 is the diameter when the first dot A1 is circular, and is the average value of the maximum diameter when the first dot A1 is irregular.

  The height H2 of the second dot A2 is not particularly limited. For example, it is 1.3 times or more the height H1 of the first dot A1. The height H1 of the first dot A1 is, for example, 50 to 300 μm, and preferably 100 to 200 μm. The height H of each dot is a distance connecting two points where a straight line passing through the contact point between the dot and the first nonwoven fabric 1 or the second nonwoven fabric 2 and the outer surface of the dot intersects with the first nonwoven fabric. It is obtained as an average value.

The ratio of the first dot A1 and the second dot A2 is not particularly limited. Especially, it is preferable that the ratio of 2nd dot A2 with respect to the total number of 1st dot A1 and 2nd dot A2 is larger than 50% of the said total number from a viewpoint of peeling suppression. Further, the ratio of the second dots A2 is preferably smaller than 80% of the total number. The number of the second dots A2 per unit area is not particularly limited, but is preferably 50 to 250 / cm ² from the viewpoint of suppressing peeling.

  Note that the physical property values such as the area S1 of the first dots A1 are average values of the first dots A1 when there are a plurality of the first dots A1. Similarly, when there are a plurality of second dots A2, the physical property values such as the area S2 of the second dots A2 are average values thereof.

  The physical property values of the second dot A2 and the first dot A1 can be calculated from, for example, a region R that includes 20 or more total of the second dots A2 and the first dots A1. That is, after taking a photograph of the laminate of the first nonwoven fabric 1 and the second nonwoven fabric 2 from the normal direction of the main surface, and determining the region R including 20 or more total of the second dots A2 and the first dots A1, The physical property value for each dot is calculated. The height of the dots may be measured by taking a photograph of a cross section that cuts each dot included in the region R.

The method for forming the second dot A2 is not particularly limited. For example, a method of spraying more than 5 g / m ^{2 of} adhesive particles on the second nonwoven fabric 2 side (the main surface side) of the laminate of the first nonwoven fabric 1 and the second nonwoven fabric 2 can be mentioned. As a result, at least some of the adhesive particles are adhered to the surface of the laminate so that some of them overlap each other. Thereafter, by melting the adhesive, the overlapping adhesive particles are fused to form a second dot A2.

That is, the laminated nonwoven fabric 10A (10) prepares a first preparation step for preparing the first nonwoven fabric containing the first fibers, and a raw material liquid containing a raw material resin for the second fibers and a solvent for dissolving the raw material resins. A second preparation step, a third preparation step of preparing a third nonwoven fabric containing third fibers, and a raw material liquid is sprayed on the first nonwoven fabric to generate second fibers from the raw material liquid, and one of the first nonwoven fabrics A non-woven fabric forming step of depositing second fibers on the main surface, an adhesive spraying step of spraying adhesive particles on the main surface of the first non-woven fabric on which the second fibers are deposited, and the main surface. And a laminating step of laminating the third nonwoven fabric via the second fiber on the first nonwoven fabric having the melted adhesive. At this time, the spraying amount of the adhesive is set larger than 5 g / m ² .

The amount of adhesive sprayed is preferably greater than 5.5 g / m ² in that the second dots A2 are easily formed. On the other hand, the spraying amount of the adhesive is preferably less than 20 g / m ² . When the amount of the adhesive sprayed exceeds this range, there is a concern about an increase in manufacturing costs and an increase in transportation costs due to an increase in the mass of the laminated nonwoven fabric.

  In the heating process, the plurality of adhesive particles adhering to the surface of the laminate are melted and fused so that a part of them overlap each other. The fused adhesive particles (fused particles) are crushed in the laminating process to form the second dots A2. At this time, the height of the fused particles from the second nonwoven fabric 2 or the first nonwoven fabric 1 is higher than the height of the single particles. Therefore, the fused particles are preferentially pressurized against the single particles. Therefore, a large load is not applied to the second fibers other than the second fibers between the fused particles and the first nonwoven fabric 1, and deformation is suppressed. While the second fiber between the fused particles (second dot A2) and the first nonwoven fabric 1 has a small contribution to the dust collection efficiency, the second fibers other than the second fiber greatly contribute to the dust collection efficiency. To do. Since the deformation of the second fiber that contributes to the dust collection efficiency is suppressed, the dust collection efficiency is easily improved.

  The manufacturing method of the above laminated nonwoven fabric is, for example, transporting the first nonwoven fabric 1 from the upstream to the downstream of the line, forming the second nonwoven fabric on the main surface of the transported first nonwoven fabric, and then laminating the third nonwoven fabric. It can be implemented by a manufacturing system. Such a production system includes, for example, (1) a first nonwoven fabric supply device that supplies the first nonwoven fabric to the transport belt, and (2) a second electrospinning mechanism that generates second fibers from the raw material liquid by electrostatic force. A non-woven fabric forming device, (3) an adhesive spraying device for spraying adhesive from above the second non-woven fabric fed from the second non-woven fabric forming device, and (4) a heating device for melting the sprayed adhesive; 5) A third nonwoven fabric laminating device for laminating the third nonwoven fabric is provided from above the second nonwoven fabric fed from the heating device.

  Hereinafter, although the manufacturing method of a laminated nonwoven fabric and the manufacturing system which performs this are demonstrated, referring FIG. 2, the following systems and manufacturing methods do not limit this invention. FIG. 2 is a diagram schematically showing a configuration of an example of a manufacturing system for the laminated nonwoven fabric 10. The production system 200 constitutes a production line for producing the laminated nonwoven fabric 10.

  First, the first nonwoven fabric 1 is prepared. In the manufacturing system 200, the first nonwoven fabric 1 is conveyed from the upstream side to the downstream side of the production line by the conveying rolls 11, 31, 41, 51 and the conveying conveyor 21. The most upstream of the manufacturing system 200 is provided with a first nonwoven fabric supply device 201 that houses therein the first nonwoven fabric 1 wound in a roll shape. The supply device 201 rotates the first supply reel 12 by the motor 13 and supplies the first nonwoven fabric 1 wound around the first supply reel 12 to the transport roll 11.

  The first nonwoven fabric 1 is transported to the electrospinning unit 202 by the transport roll 11. The electrospinning mechanism provided in the electrospinning unit 202 includes an emitter 23 for discharging the raw material liquid of the second fibers 2F installed in the upper part of the apparatus, and charging means for positively charging the discharged raw material liquid ( And a transport conveyor 21 that transports 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. Note that the number of electrospinning units 202 is not particularly limited, and may be one or two or more.

  When there are a plurality of electrospinning units 202 and / or emitters 23, the average fiber diameter of the second fibers 2F formed may be changed for each electrospinning unit 202 or for each emitter 23. 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 system and a desired fiber diameter, it should just be 100-600 mm, for example. The emitter 23 is installed above the electrospinning unit 202, and a second support 25 extending downward from the first support 24 parallel to the transport direction of the first nonwoven 1 is used, and the longitudinal direction of the emitter 23 is the first nonwoven. It is supported so as to be parallel to the main surface of 1. 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 to 200 kV) according to the voltage applied by the voltage application device 26 can be provided between the emitter 23 and the counter electrode 27. The configuration of the charging unit is not particularly limited. For example, the counter electrode 27 may be negatively charged. Moreover, you may comprise the belt part of the conveyance conveyor 21 from a conductor instead of providing the counter electrode 27. FIG.

  The emitter 23 is made of a conductor, has a long shape, and is hollow inside. The hollow portion serves as a storage portion that stores the 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.

  An appropriate solvent may be selected as the solvent contained in the raw material liquid 22 in accordance with the type of raw material resin and manufacturing conditions. For example, methanol, ethanol, 1-propanol, 2-propanol, hexafluoroisopropanol, tetraethylene glycol, triethylene glycol, dibenzyl alcohol, 1,3-dioxolane, 1,4-dioxane, methyl ethyl ketone, methyl isobutyl ketone, methyl- n-hexyl ketone, methyl-n-propyl ketone, diisopropyl ketone, diisobutyl ketone, acetone, hexafluoroacetone, phenol, formic acid, methyl formate, ethyl formate, propyl formate, methyl benzoate, ethyl benzoate, propyl benzoate, acetic acid Methyl, ethyl acetate, propyl acetate, dimethyl phthalate, diethyl phthalate, dipropyl phthalate, methyl chloride, ethyl chloride, methylene chloride, chloroform, o-chlorotoluene, p- Lorotoluene, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, trichloroethane, dichloropropane, dibromoethane, dibromopropane, methyl bromide, ethyl bromide, propyl bromide, acetic acid, benzene, toluene, hexane, cyclohexane , Cyclohexanone, cyclopentane, o-xylene, p-xylene, m-xylene, acetonitrile, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide (DMAc), dimethyl sulfoxide, pyridine, water, etc. it can. These may be used alone or in combination of two or more. Especially, when forming the 2nd fiber 2F containing polyether sulfone (PES) by an electrospinning method so that it may mention later, DMAc is preferable at the point suitable for an electrospinning method and the point which dissolves PES easily.

An inorganic solid material may be added to the raw material liquid 22. Examples of inorganic solid materials include oxides, carbides, nitrides, borides, silicides, fluorides, sulfides, and the like. Among these, it is preferable to use an oxide from the viewpoint of workability. Examples of the oxide include Al ₂ O ₃ , SiO ₂ , TiO ₂ , Li ₂ O, Na ₂ O, MgO, CaO, SrO, BaO, B ₂ O ₃ , P ₂ O ₅ , SnO ₂ , ZrO ₂ , K _2. O, Cs ₂ O, ZnO, Sb ₂ O ₃ , As ₂ O ₃ , CeO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO, Fe ₂ O ₃ , CoO, NiO, Y ₂ O ₃ , Lu ₂ O ₃ , Yb ₂ O ₃ , HfO ₂ , Nb ₂ O _{5 and the} like. These may be used alone or in combination of two or more.

  The mixing ratio of the solvent and the raw material resin in the raw material liquid 22 varies depending on the type of the selected solvent and the type of the raw material resin. The ratio of the solvent in the raw material liquid 22 is, for example, 60% by mass to 95% by mass.

  The electrospinning mechanism for forming the second fibers 2F is not limited to the above configuration. If it is a mechanism capable of generating the second fibers 2F from the raw material liquid by electrostatic force in the generation space of the predetermined second fibers 2F and depositing the generated second fibers 2F on the main surface of the first nonwoven fabric 1, It can be used without particular limitation. For example, the shape of the cross section perpendicular to the longitudinal direction of the emitter 23 may be a shape (V-type nozzle) that gradually decreases from the top to the bottom.

  After the 2nd nonwoven fabric 2 is formed, the laminated body of the 1st nonwoven fabric 1 and the 2nd nonwoven fabric 2 is conveyed to the adhesive agent spreading apparatus 203. FIG. In the adhesive spraying device 203, the adhesive particles 4 are sprayed from above the second nonwoven fabric 2. The adhesive 4 is sprayed by, for example, a spray method or free fall.

  The adhesive spraying device 203 includes, for example, a spraying device 34 that includes an adhesive tank 32 that stores the adhesive 4 installed above the adhesive spraying device 203 and a spraying member 33 that sprays the adhesive 4. It has.

  After the adhesive 4 is sprayed, the adhesive 4 is heated by the heating device 204 including the heating device 42 before the third nonwoven fabric 3 is laminated on the laminate. As a result, the adhesive particles partially overlapping and adhering are fused. In the heating device 204, the solvent contained in the second nonwoven fabric 2 is also removed.

  The heating device 42 is not particularly limited, and a known device may be appropriately selected. The heating temperature may be appropriately set according to the boiling point of the solvent and the melting point of the adhesive 4. The heating temperature is adjusted so that the surface of the laminate is preferably 100 to 200 ° C, more preferably 120 to 170 ° C. In addition, the softening temperature of PES which is one of the materials of a 2nd fiber is 200-230 degreeC.

  Next, the laminate including the fused adhesive particles 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 from above the laminated body and laminated on the laminated body via the adhesive 4. When the third nonwoven fabric 3 is long, the third nonwoven fabric 3 may be wound around the second reel 52 in the same manner as the first nonwoven fabric 1. In this case, the 3rd nonwoven fabric 3 is laminated | stacked on a laminated body, rolling out from the 2nd reel 52. FIG.

  After the third nonwoven fabric 3 is laminated, the laminated nonwoven fabric 10 and the third nonwoven fabric are pressed by pressing the laminated nonwoven fabric 10 while applying pressure with a pair of pressure rolls 53 (53a and 53b) disposed above and below the laminated nonwoven fabric 10. 3 may be further brought into close contact with each other.

  Finally, the laminated nonwoven fabric 10 is carried out from the third nonwoven fabric laminating device 205 and is conveyed via the roll 61 to the collecting device 206 arranged on the further downstream side. 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.

(Second Embodiment)
As shown in FIG. 3, the laminated nonwoven fabric 10 </ b> B according to the present embodiment is replaced with the first nonwoven fabric and the second nonwoven fabric, the base material layer 5 a including the first fibers 1 </ b> F, the first fibers 1 </ b> F, and the second fibers 2 </ b> F. It is the same as that of 1st Embodiment except providing the 1a nonwoven fabric 5 containing the composite layer 5b containing. In this case, the third nonwoven fabric 3 is laminated so as to face the composite layer 5 b of the first a nonwoven fabric 5, and the adhesive 4 is interposed between the composite layer 5 b and the third nonwoven fabric 3. The base material layer 5a corresponds to the first nonwoven fabric 1 and has a function of maintaining the shape of the laminated nonwoven fabric 10B. For example, when a laminated nonwoven fabric is pleated, the shape of the pleat is maintained by the base material layer. The composite layer corresponds to the second non-woven fabric and exhibits a dust collecting effect.

  In the same way as the method for obtaining the laminate of the first nonwoven fabric and the second nonwoven fabric, the first a nonwoven fabric 5 is formed by applying the second fibers 2F on the base material including the first fibers 1F using, for example, an electrospinning method. It can be obtained by depositing. At this time, for example, the accumulation amount of the second fibers 2F is reduced. Thereby, most (for example, 90 mass% or more) of the second fibers 2F deposited on the base material are buried in the gaps between the first fibers 1F to form the composite layer 5b. Therefore, separation of the first fiber 1F and the second fiber 2F is suppressed. Further, the second fiber 2F of the composite layer 5b does not form a layer having self-supporting properties. Therefore, even if a part of the second fiber 2F is separated from the first fiber 1F, it is unlikely that another second fiber 2F is separated in a chain manner. Therefore, peeling of the 3rd nonwoven fabric 3 becomes still easier to be suppressed.

  From the viewpoint of pressure loss, the thickness of the first non-woven fabric 5 (the total of the base material layer 5a and the composite layer 5b) 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 dust collection efficiency, the second fibers 2F are preferably arranged in the thickness direction of the first a nonwoven fabric 5 in a region from one main surface of the first a nonwoven fabric 5 to 2 μm. More preferably, it is disposed in a region from the main surface to 1 μm. In other words, the thickness of the composite layer 5b is preferably 0.1 μm or more and 2 μm or less, and more preferably 0.5 μm or more and 1 μm or less.

[Air cleaner]
As illustrated in FIG. 4, the air purifier 100 according to the present invention includes a gas suction part 101, a gas discharge part 102, and a laminated nonwoven fabric 10 disposed therebetween. 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. An air cleaner provided with the laminated nonwoven fabric 10 can suppress a pressure loss small over a long period of time. 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 third 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.

[Example]
Examples of the present invention will be specifically described below, but the present invention is not limited to these examples.

[Example 1]
A base material mainly composed of cellulose (thickness T1: 300 μm, D1: 15 μm, mass per unit area: 42 g / m ² , porosity P1: 61%) was used as the first nonwoven fabric. Using the manufacturing system as shown in FIG. 2, the second nonwoven fabric was formed by depositing the second fibers on the conveyed first nonwoven fabric 1 to obtain a laminate. At this time, the emitter was continuously swung in a direction perpendicular to the conveying direction, and the gas flow was made to collide with the second fiber from the upstream side of the first nonwoven fabric in the generation space. As a raw material liquid for the second fiber, a DMAc solution containing 20% by mass of PES was used. D2 was 273 nm.

Next, a powdery adhesive (polyester hot melt resin, melting point: about 100 ° C.) was sprayed from the second nonwoven fabric 2 side of the laminate by free-fall. The application amount of the adhesive was 6 g / m ² and the average particle size was 215 μm. After heating so that the surface of a laminated body might be 158 degreeC, the 3rd nonwoven fabric was laminated | stacked from the 2nd nonwoven fabric 2 side. As the third nonwoven fabric, a melt blown nonwoven fabric (T3: 165 μm, D3: 5 μm, P3: 61 vol%, mass per unit area: 18 g / m ² ) mainly composed of polypropylene fibers was used. Subsequently, the laminated nonwoven fabric was obtained by pressure bonding with a pressure roll. The pressure for pressure bonding was 5 kPa.

  The 3rd nonwoven fabric of the obtained laminated nonwoven fabric was peeled so that an adhesive agent might not remain on the 3rd nonwoven fabric side. About the remaining laminated body, it observed using the microscope from the 2nd nonwoven fabric side, and the area | region R containing 20 or more dot adhesives was determined. FIG. 5 shows a micrograph (50 ×) of a part of the region R.

The region R included a first dot that appeared to be formed by a single adhesive particle, and a second dot that seemed to be a fusion of 2 to 8 adhesive particles. The ratio of the second dots to the total number of the first dots and the second dots in the region R was 62%, and the second dots were included at 98 / cm ² . The average diameter of the first dots was 179 μm, and the average maximum diameter of the second dots was 313 μm. Furthermore, each dot was cut by a straight line passing through the vicinity of the center of each dot, and their cross sections were confirmed. The height of the first dot was 121 μm, and the height of the second dot was 225 μm.

(Evaluation of pressure loss)
Separately, the laminated nonwoven fabric was cut into 12 cm × 12 cm, and a suction test was performed at a surface wind speed of 5.3 cm / sec. 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. For measuring the air pressure, a measuring machine (manometer) conforming to the standard of JIS B 9908 was used. The results are shown in Table 1.

(Evaluation of adhesive strength)
Furthermore, separately, the laminated nonwoven fabric was cut into a width of 30 mm and a length of 180 mm, and the peel strength between the first nonwoven fabric and the third nonwoven fabric was measured by a method based on JISZ0237. Specifically, the first nonwoven fabric side was affixed to the pedestal with a double-sided tape, and the third nonwoven fabric was pulled in the 90 ° direction at 5 mm / sec with a scissors jig, and the peel strength was measured.

[Comparative Example 1]
A laminated nonwoven fabric was prepared and the region R was determined in the same manner as in Example 1 except that the application amount of the adhesive was 2 g / m ² . In the region R, a first dot that was considered to be formed by a single adhesive particle was confirmed, but a second dot that was considered that two or more adhesive particles were fused was not confirmed. FIG. 6 shows a micrograph (50 ×) of a part of the region R. Separately, pressure loss and peel strength were evaluated for the obtained laminated nonwoven fabric in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]
Example 1 except that an adhesive having an average particle size of 334 μm was used, that the amount of adhesive applied was 2 g / m ² , and that the surface of the laminate was heated to 177 ° C. In the same manner as above, a laminated nonwoven fabric was prepared, and the region R was determined. In the region R, a first dot that was considered to be formed by a single adhesive particle was confirmed, but a second dot that was considered that two or more adhesive particles were fused was not confirmed. The particle size of the first dots was 412 μm. Separately, pressure loss and peel strength were evaluated for the obtained laminated nonwoven fabric in the same manner as in Example 1. The results are shown in Table 1.

  The laminated nonwoven fabric of the present invention suppresses the peeling of the nonwoven fabric having fibers having a small average fiber diameter, so that the filter medium of the air cleaner or the air conditioner, the separation sheet for the battery, the membrane for the fuel cell, the pregnancy test sheet, etc. It is suitable as an in-vitro inspection sheet, a medical sheet for cell culture, a dust-proof cloth such as a dust mask, a dust-proof clothing, a cosmetic sheet, a wiping sheet for wiping off dust, and the like.

  1: 1st nonwoven fabric, 1F: 1st fiber, 2: 2nd nonwoven fabric, 2F: 2nd fiber, 3: 3rd nonwoven fabric 3F: 3rd fiber, 4: Adhesive agent, 5: 1a nonwoven fabric, 5a: Base material Layer, 5b: composite layer, 10, 10A, 10B: laminated nonwoven fabric, 11: transport roll, 12: first supply reel, 13: motor, 21: transport conveyor, 22: raw material liquid, 23: discharger, 24: first 1 support, 25: second support, 26: voltage application device, 27: counter electrode, 28: pump, 29: raw material liquid tank, 31: transport roll, 32: adhesive tank, 33: spraying member, 34: Spreading device, 41: transport roll, 42: heating device, 51: transport roll, 52: second supply reel, 53, 53a, 53b: pressure roll, 61: roll, 62: recovery reel, 63: motor, 100: Air cleaner, 101: suction part, 102: discharge Outlet part, 103: Prefilter, 104: Deodorizing filter, 200: Production system, 201: First nonwoven fabric supply device, 202: Electrospinning unit, 203: Adhesive spraying device, 204: Heating device, 205: Third nonwoven fabric Laminating device 206: Recovery device

Claims (7)

A first nonwoven including first fibers;
A second nonwoven fabric laminated on the first nonwoven fabric and containing second fibers;
Is laminated on the main surface side which does not face the first nonwoven fabric the second nonwoven fabric, and a third nonwoven comprising a third fiber,
An adhesive interspersed between the first nonwoven fabric and the third nonwoven fabric,
The average fiber diameter D2 of the second fibers is 3 μm or less,
The average fiber diameter D1 of the first fibers and the average fiber diameter D2 satisfy the relationship of D1> D2,
The adhesive forms a plurality of dot regions;
The dot region, viewed contains a first dot formed by a single particle of the adhesive, and a second dots formed by the fusion adherend two or more particles of the adhesive,
When viewed from a cross section perpendicular to the main surface of the second nonwoven fabric, the height of the second dots from the surface of the second nonwoven fabric on the third nonwoven fabric side is the second of the first dots. A laminated nonwoven fabric that is larger than the height of the nonwoven fabric from the surface of the third nonwoven fabric side . A 1a nonwoven fabric comprising first and second fibers;
A third non-woven fabric laminated on the first non-woven fabric and containing a third fiber;
An adhesive interposed between the first non-woven fabric and the third non-woven fabric,
The average fiber diameter D2 of the second fibers is 3 μm or less,
The average fiber diameter D1 of the first fibers and the average fiber diameter D2 satisfy the relationship of D1> D2,
The first a nonwoven fabric includes a base material layer including the first fibers, and a composite layer including the first fibers and the second fibers, disposed on a main surface facing the third nonwoven fabric;
The adhesive forms a plurality of dot regions;
The dot region, viewed contains a first dot formed by a single particle of the adhesive, and a second dots formed by the fusion adherend two or more particles of the adhesive,
When viewed from a cross section perpendicular to the main surface of the 1a nonwoven fabric facing the third nonwoven fabric, the height of the second dot from the surface of the composite layer on the third nonwoven fabric side is the first height. A laminated non-woven fabric that is larger than the height of the composite layer of the dots from the surface of the third non-woven fabric side .   The laminated nonwoven fabric according to claim 1 or 2, wherein the number of the second dots is larger than the number of the first dots. The mass per unit area of the adhesive is greater than 5 g / m ^2, laminated nonwoven fabric according to any one of claims 1 to 3.   The laminated nonwoven fabric according to any one of claims 1 to 4, wherein the average fiber diameter D2 is 1 µm or less. A gas inlet,
The gas discharge part;
An air cleaner comprising: the laminated nonwoven fabric according to any one of claims 1 to 5, which is disposed between the suction portion and the discharge portion. A first preparation step of preparing a first nonwoven fabric including first fibers;
A second preparation step of preparing a raw material resin containing a raw material resin as a raw material of the second fiber and a solvent for dissolving the raw material resin;
A third preparation step of preparing a third nonwoven fabric containing third fibers;
Injecting the raw material liquid on the first non-woven fabric, generating second fibers from the raw material liquid, and depositing the second fibers on one main surface of the first non-woven fabric; and
An adhesive spraying step of spraying adhesive particles on the main surface of the first nonwoven fabric on which the second fibers are deposited;
A heating step of melting the adhesive spread on the main surface;
A lamination step of laminating the third nonwoven fabric via the second fibers on the first nonwoven fabric having the molten adhesive,
Application rate of the adhesive, rather greater than 5 g / m ^2,
The manufacturing method of a laminated nonwoven fabric whose average particle diameter of the said adhesive agent is 150 micrometers or more and less than 200 micrometers .