JP2009263818A - Laminated nonwoven fabric structure and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated nonwoven fabric structure having excellent delamination resistance of the laminated nonwoven fabrics by decreasing the difference shrinkage of the nonwoven fabrics constituting the laminate, and to provide a method for producing the structure. <P>SOLUTION: The laminated nonwoven fabric structure is obtained by laminating a nonwoven fabric (A) 1 composed of fibers having a fiber diameter of 5-100 μm and a nanofiber nonwoven fabric (B) 2 composed of nanofibers having a fiber diameter of 1-1,000 nm, wherein both of the nonwoven fabric (A) 1 and the nanofiber nonwoven fabric (B) 2 are made of a polyvinyl alcohol (PVA) resin fiber. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a nonwoven fabric laminated structure excellent in peel resistance of laminated nonwoven fabric and a method for producing the same, and relates to a nonwoven fabric laminated structure used for a high-precision filter and the like and a method for producing the same.

  Recently, in the electronics field, the mechatronics field, the water quality field, the field dealing with drugs, medicines and foods, etc., it is highly accurate to remove very fine impurities out of the system and recover the necessary trace components. Management is required. For this reason, for example, filters for air purifiers, filters for dust removal for industrial use, filters for producing pure water and for purifying chemicals, pharmaceutical / medical filters, battery separators, etc. are thinner and have a uniform basis weight. In addition, high-precision filters and separators have been required.

  Therefore, a nonwoven fabric formed of nanofibers (hereinafter referred to as “nanofiber nonwoven fabric”) as a high-accuracy filter material or the like is particularly useful since it has a small pore size and a uniform pore size distribution.

  Among the nanofibers, PVA nanofibers formed from polyvinyl alcohol (hereinafter abbreviated as “PVA”) resins are formed from PVA resins having excellent oil resistance and solvent resistance. The PVA nanofiber non-woven fabric is excellent in solvent resistance and is suitably used as a high-precision filter material in a solvent system.

Since such a nanofiber nonwoven fabric usually lacks strength and form retention, it is generally used by being laminated together with a support. Examples of this support include a woven fabric or a nonwoven fabric made of a thermoplastic resin (see Patent Document 1). Specifically, in Patent Document 1 described above, screen wrinkles (polyester woven fabric, Example 2 etc.), nylon 6 extra fine fiber synthetic paper (Example 7), PP (polypropylene) meltblown nonwoven fabric (Example 8), etc. It is used.
JP 2005-264420 A

  However, since the PVA resin is a hydrophilic and crystalline resin, the non-woven fabric using the PVA nanofibers thus obtained has been crystallized or crystal relaxed and reorganized due to moisture absorption and water absorption. It starts to shrink. As a result, due to the difference in shrinkage from the support, there was a problem that the two peeled off during use or storage.

  The present invention has been made in view of such circumstances, and the object of the present invention is to provide a nonwoven fabric laminate structure that reduces the difference in shrinkage between nonwoven fabrics and is excellent in peel resistance of the laminated nonwoven fabric and a method for producing the same. To do.

  In order to achieve the above object, the present invention provides a nonwoven fabric obtained by laminating a nonwoven fabric (A) composed of fibers having a fiber diameter of 5 to 100 μm and a nanofiber nonwoven fabric (B) composed of nanofibers having a fiber diameter of 1 to 1000 nm. The gist of the present invention is a laminated structure in which the nonwoven fabric (A) and the nanofiber nonwoven fabric (B) are nonwoven fabrics made of polyvinyl alcohol resin fibers.

  Further, in the present invention, a method for producing the nonwoven fabric laminated structure, wherein when the nanofibers are deposited on a nanofiber collector to form a nanofiber nonwoven fabric, the nanofiber collector is used as the nanofiber collector. The manufacturing method of the nonwoven fabric laminated structure which manufactures a laminated structure with a nonwoven fabric (A) simultaneously with manufacture of a nanofiber nonwoven fabric (B) using a nonwoven fabric (A) is made into the 2nd summary.

  That is, in view of the above circumstances, the present inventors have intensively studied in order to suppress peeling between the PVA nanofiber nonwoven fabric and the support. In the process, we studied the idea of reducing the shrinkage difference by bringing the nonwoven fabric and the substrate closer together. As a result, it was found that the PVA nanofiber nonwoven fabric support can be prevented from peeling by using a PVA nonwoven fabric having a fiber diameter in the above numerical range instead of a known thermoplastic resin nonwoven fabric. Reached.

  As described above, the present invention is a nonwoven fabric laminated structure obtained by laminating a nonwoven fabric (A) made of fibers having a fiber diameter of 5 to 100 μm and a nanofiber nonwoven fabric (B) made of nanofibers having a fiber diameter of 1 to 1000 nm. The nonwoven fabric (A) and the nanofiber nonwoven fabric (B) are each a nonwoven fabric laminated structure that is a nonwoven fabric made of PVA resin fibers. For this reason, the difference of the shrinkage | contraction rate of the nonwoven fabric (A) which is a support body, and a nanofiber nonwoven fabric (B) reduces, and comes to be excellent in the peeling resistance of the laminated nonwoven fabric.

  When the non-woven fabric (A) is a spunbonded non-woven fabric containing a PVA resin containing a structural unit represented by the following general formula (1), the melting point of the specific PVA resin is low and the melt tension is low. Since it is high, hot melt spinning becomes easy, and a better spunbond nonwoven fabric can be obtained. The nonwoven fabric laminated structure obtained by this becomes more useful as a high precision filter etc. In addition, since the melting | fusing point and thermal decomposition temperature of a general PVA-type resin are close, it is difficult to heat-melt-mold and it is difficult to obtain a good spunbond nonwoven fabric.

  Furthermore, it is a method for producing the above-mentioned nonwoven fabric laminate structure, and when the nanofibers are deposited on a nanofiber collector to form a nanofiber nonwoven fabric, the nonwoven fabric (A) is used as a nanofiber collector. In order to manufacture a laminated structure with the nonwoven fabric (A) simultaneously with the production of the nanofiber nonwoven fabric (B), the nanofibers of the nanofiber nonwoven fabric (B) enter the voids of the nonwoven fabric (A). Both are intertwined with each other. Thereby, a nonwoven fabric laminated structure comes to be further excellent in peeling resistance.

  Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to this embodiment.

  As illustrated in FIG. 1, the nonwoven fabric laminated structure of the present invention includes a nonwoven fabric (A) 1 made of fibers having a fiber diameter of 5 to 100 μm, and a nonwoven fabric (B) 2 made of nanofibers having a fiber diameter of 1 to 1000 nm. It is a nonwoven fabric laminated structure formed by laminating layers. In addition, the nonwoven fabric laminated structure of this invention is not limited to FIG. 1, It can be set as other structures and shapes, such as providing another layer. First, the nonwoven fabric (A) will be described.

<< Nonwoven fabric (A) made of fibers having a fiber diameter of 5 to 100 m >>
The nonwoven fabric (A) according to the present invention may be abbreviated as a PVA-based resin fiber (hereinafter referred to as “PVA fiber”) formed using a forming material mainly composed of a PVA-based resin and spun into a fiber shape. ). In the present invention, the term “main component” refers to a component that occupies a majority of the whole, and includes the case where the whole is composed of only the main component.

  The fiber diameter of the PVA fiber which comprises the said nonwoven fabric (A) is 5-100 micrometers. Preferably it is 5-50 micrometers, Most preferably, it is 5-30 micrometers. This is because if the fiber diameter is too large, the flexibility of the nonwoven fabric (A) obtained from this fiber is lost, or the nanofibers of the nanofiber nonwoven fabric (B) are difficult to attach to the nonwoven fabric (A). Moreover, when a fiber diameter is too thin, the intensity | strength of a nonwoven fabric (A) will run short. In addition, the fiber diameter in this invention means the average diameter in the cross section of the fiber obtained by measuring from the micrograph of a nonwoven fabric, and when a cross-sectional shape is non-circular, it has the same area as a cross section. The diameter of the circle is regarded as the fiber diameter.

  Moreover, the average fiber length of this PVA fiber is generally less than 300 mm, a long fiber of 300 mm or more, and the like due to the difference in the production method of the nonwoven fabric (A). From the viewpoints of strength, flexibility, production cost and the like of the obtained nonwoven fabric (A), long fibers are preferable. Hereinafter, the nonwoven fabric composed of short fibers (hereinafter abbreviated as “short fiber nonwoven fabric”) and the nonwoven fabric composed of long fibers (hereinafter abbreviated as “long fiber nonwoven fabric”) will be described separately.

<Short fiber nonwoven fabric (A-1)>
As described above, the short fiber nonwoven fabric (A-1) is formed by, for example, laminating short fibers produced by spinning, cutting, or the like using a forming material mainly composed of a PVA resin to form a web. This is obtained by a water jet method or the like in which a high-pressure water flow is jetted to bond the fibers to form a nonwoven fabric. If necessary, the short fiber or the short fiber nonwoven fabric is subjected to treatment such as heat treatment, stretching, and other appropriate water insolubilization treatment.

  The PVA resin used for the short fiber nonwoven fabric (A-1) is not particularly limited as long as it is a polymer having a vinyl alcohol unit. For example, a partially saponified product of polyvinyl acetate or a complete saponified product. Examples thereof include saponified products of copolymers of vinyl esters and monomers copolymerizable therewith.

  Examples of the monomer that can be copolymerized with the vinyl ester include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, acrylic acid, methacrylic acid, crotonic acid, and maleic acid. , Unsaturated acids such as maleic anhydride, itaconic acid or their salts or mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide, ethylene sulfonic acid, allyl sulfonic acid, meta Olefin sulfonic acids such as allyl sulfonic acid or salts thereof, alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, etc. Compounds having a group, vinyl ketone, N- vinylpyrrolidone, vinyl chloride, vinylidene chloride, oxyalkylene group-containing compounds, and the like.

  The average saponification degree of the PVA-based resin is usually 85 mol% or more, and particularly preferably 90 to 100 mol%. This is because if the average saponification degree is too low, the water resistance tends to be poor.

  The average degree of polymerization (measured in accordance with JIS K 6726) of the PVA-based resin is usually in the range of 150 to 5000, particularly 500 to 3000. If the average degree of polymerization is too low, the strength of the nonwoven fabric tends to decrease. Conversely, if the average degree of polymerization is too high, the spinning solution tends to increase in viscosity.

  Although the said short fiber nonwoven fabric (A-1) uses a molding material which has specific PVA as a main component, it is preferable that PVA-type resin accounts for 80 weight% or more of the whole forming material.

  Examples of components other than the PVA-based resin include, for example, plasticizers, lubricants, pigment dispersants, thickeners, anti-sticking agents, fluidity improvers, surfactants, antifoaming agents, mold release agents, penetrating agents, and dyes. Well-known additives such as pigments, fluorescent brighteners, ultraviolet absorbers, antioxidants, antiseptics, antifungal agents, paper strength enhancers, and crosslinking agents can be appropriately blended.

  Below, an example of the method of manufacturing a short fiber nonwoven fabric (A-1) is demonstrated according to each process.

(I) Stock solution preparation process The PVA resin is heated and dissolved at 80 ° C. or higher in a dissolver for 1 to 10 hours so as to have a predetermined concentration (usually 3 to 30% by weight). This is because if the concentration of the solution is too low, the formation of PVA fibers tends to be poor, and conversely if too high, spinning tends to be inefficient and impractical. Further, an optional additive such as a crosslinking agent, a dye, an anti-coloring agent and a neutralizing agent may be further added in such an amount that it does not matter for subsequent spinning.

(Ii) Spinning Step The PVA solution (stock solution) obtained above is extruded through a spinning nozzle into a coagulating solution at 10 to 60 ° C. As this coagulant, salt such as mirabilite, ammonium sulfate, sodium phosphate and alkali such as sodium hydroxide can be used, but industrially, mirabilite aqueous solution is mainly used due to coagulation ability and economy. Further, in order to prevent coloring in the above process, zinc sulfate, magnesium sulfate or a small amount of sulfuric acid may be added to the coagulating liquid, or a trace amount of heavy metal salts such as copper or manganese may be added.

  As for the spinning nozzle, a nozzle having an arbitrary shape such as a circle or a corner is used, and an array such as a crosshair type, a radiation type, or a star shape is appropriately employed. The nozzle diameter is usually preferably 0.01 to 1.0 mm. The yarn cake solidified in this spinning step is taken out from the coagulating liquid and then stretched as necessary. The stretching condition is usually about 120 to 220 ° C., and the stretching ratio is usually preferably about 5 to 20 times. The yarn is then cut into short fibers having a fiber length of usually 1.5 to 300 mm, particularly 2 to 75 mm, and a single fiber fineness of usually 0.01 to 100 denier, especially 0.1 to 15 denier. Used as a raw material for nonwoven fabrics.

(Iii) Nonwoven fabric manufacturing process The PVA short fibers obtained above are laminated on a flat surface such as a belt conveyor to form a web. A high-pressure water stream is jetted onto the web to bond the fibers to form a nonwoven fabric (water jet system). By this method, it becomes possible to impart water resistance to water at about body temperature while maintaining the texture, which has been impossible with conventional PVA nonwoven fabrics. There is no restriction | limiting in particular about the apparatus for that, A so-called spunlace method nonwoven fabric manufacturing apparatus etc. can be used.

The water pressure is usually 20 to 400 kg / cm ² , particularly preferably 70 to 150 kg / cm ² . If the water pressure is too low, there is a tendency that a nonwoven fabric having sufficient strength cannot be produced, and conversely, if the water pressure is too high, it tends to be economically undesirable. The water flow is practically a water column flow, but can be a sprinkling flow. Then, the target short fiber nonwoven fabric (A-1) is obtained by dehydrating and drying the water contained in the nonwoven fabric. In addition, it is preferable that the said dehydration and drying are dehydration with a pressure roll etc., and are subsequently dried at the temperature of about 60-200 degreeC.

  Next, the long fiber nonwoven fabric (A-2) will be described.

<Non-fiber nonwoven fabric (A-2)>
As described above, the long-fiber nonwoven fabric (A-2) is obtained by using a forming material mainly composed of a PVA-based resin, for example, by using a long fiber obtained by melt spinning the same.

  As the PVA resin used for the long-fiber nonwoven fabric (A-2), a specific PVA resin having a 1,2-diol structural unit represented by the following general formula (1) is usually preferably used. A general PVA-based resin has a melting point and a thermal decomposition temperature that are close to each other, so that hot melt molding tends to be difficult. For this reason, it is conceivable to lower the melting point to facilitate hot melt molding, but if the saponification degree is lowered, acetic acid is generated due to thermal decomposition of the acetyl group, which remains in the product and causes odor. ing. In such a situation, even if the specific PVA-based resin has a high saponification degree, it has a low melting point and a high melt tension, so that hot melt molding is easy.

  The specific PVA resin has a 1,2-diol structural unit represented by the general formula (1) as described above. Other structural parts are composed of a vinyl alcohol structural unit and a vinyl acetate structural unit in the same manner as a normal PVA-based resin, and the ratio is appropriately adjusted depending on the degree of saponification.

In the 1,2-diol structural unit represented by the general formula (1), R ^{1 to} R ³ and R ^{4 to} R ⁶ in the formula (1) are a hydrogen atom or a monovalent organic group. May be the same as or different from each other. Among them, it is preferable from the viewpoint of the copolymerization reactivity and industrial handling of monomers in the production process R ¹ to R ³ and R ⁴ to R ⁶ are all hydrogen atoms. However, at least a part of R ^{1 to} R ³ and R ^{4 to} R ⁶ may be an organic group as long as the resin characteristics are not significantly impaired. The organic group is not particularly limited, and examples thereof include alkyl groups having 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and tert-butyl group. It may have a substituent such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, or a sulfonic acid group, if necessary.

  Further, in the 1,2-diol structural unit represented by the general formula (1), X in the formula (1) is an excessively low PVA crystallinity in that there is no thermal stability inhibiting factor during melt spinning. A single bond is preferred because it does not decrease, does not impede melt fluidity, and the like. Here, X being a single bond means that X itself is a bond.

Note that X may be various linking chains as long as the effects of the present invention are not impaired. Examples of the bonding chain include hydrocarbon groups such as alkylene, alkenylene, alkynylene, phenylene, and naphthylene (these hydrocarbon groups may be substituted with halogen such as fluorine, chlorine, and bromine), and -O. _{-, - (CH 2 O)} m -, - (OCH 2) m -, - (CH 2 O) m CH 2 -, - CO -, - COCO -, - CO (CH 2) m CO -, - CO (C ₆ H ₄ ) CO—, —S—, —CS—, —SO—, —SO ₂ —, —NR—, —CONR—, —NRCO—, —CSNR—, —NRCS—, —NRNR—, _{-HPO 4 -, - Si (OR} ) 2 -, - OSi (OR) 2 -, - OSi (OR) 2 O -, - Ti (OR) 2 -, - OTi (OR) 2 -, - OTi (OR _{) 2 O -, - Al (} OR) -, - OAl (OR) -, OAl (OR) O-, and the like.

In each of the above bond chains, R is an arbitrary substituent, and examples thereof include a hydrogen atom and an alkyl group, which may be the same or different from each other, and the repeating number m is a natural number. Among the above-mentioned bonding chains, an alkylene group having 6 or less carbon atoms and —CH ₂ OCH ₂ — are preferable from the viewpoint of stability during production or use.

  Accordingly, in the present invention, in the specific PVA resin, the 1,2-diol structure represented by the following formula (1a) is used as the 1,2-diol structural unit represented by the general formula (1). It is particularly preferable to use a PVA resin having a unit.

  The production method of the specific PVA resin used in the present invention is not particularly limited. For example, (α) vinyl acetate and 3,4-diacyloxy-1-butene, particularly 3,4-diacetoxy-1- Method of saponifying a copolymer with butene, (β) Method of saponifying and decarboxylating a copolymer of vinyl acetate and vinyl ethylene carbonate, (γ) Vinyl acetate and 2,2-dialkyl-4-vinyl It can be produced by a production method such as a method for saponifying and deketalizing a copolymer with -1,3-dioxolane, or a method for saponifying a copolymer of (δ) vinyl acetate and glycerin monoallyl ether. it can. Among them, there is an advantage at the time of production that the polymerization proceeds well and it is easy to uniformly introduce the 1,2-diol structural unit into the PVA-based resin, and there are problems in fiberizing the obtained PVA-based resin. It is preferable to employ the production method (α) from the viewpoints of few points and the characteristics of the final PVA fiber.

  The average degree of polymerization (measured according to JIS K 6726) of the specific PVA-based resin thus obtained is usually 250 to 500, particularly 300 to 400, more preferably 300 to 350. That is, if the average degree of polymerization is too low, the fiber strength is too weak, and there is a tendency that thread breakage occurs frequently during production, making it difficult to form a nonwoven fabric. On the other hand, if it is too high, the fluidity is low, the stretchability at the time of spinning is low, and there is a tendency that the yarn does not become thin.

  The degree of saponification of the specific PVA resin is preferably 80 to 100 mol%, particularly 85 to 99.9 mol%, more preferably 88 to 99.9 mol%. That is, if the degree of saponification is too low, long run properties (long-time stable maneuverability such as injection molding and melt spinning) tend to be reduced, and acetic acid odor tends to be generated. The degree of saponification in the present invention is expressed as the rate of change (mol%) of a vinyl ester monomer to a hydroxyl group such as an ester moiety.

  Furthermore, as the amount of 1,2-diol bonded to the specific PVA resin, that is, the content (degree of modification) of the 1,2-diol structural unit represented by the general formula (1), for example, When considering use as a nonwoven fabric, it is usually 0.1 to 12 mol%, particularly 1 to 10 mol%, more preferably 3 to 8 mol%. That is, if the degree of modification is too small, the melting point becomes high and the moldability is lowered, the melt tension is lowered, and the yarn is broken. On the other hand, if the amount is too large, the hygroscopicity becomes high and the shrinkage of the nonwoven fabric tends to be remarkable.

  The specific PVA-based resin may be used alone, but other PVA-based resins may be used in combination as long as the characteristics, particularly hot melt moldability, are not impaired.

  Examples of the other PVA resins include unmodified PVA resins (polymerization degree 300 to 500, saponification degree 80 mol% or more), carboxylic acid modified PVA resins, acetal modified PVA resins, amide modified PVA resins. Vinyl ether modified PVA resin, α-olefin modified PVA resin, vinyl ester modified PVA resin, amine modified PVA resin, oxyalkylene modified PVA resin and the like. These are appropriately blended as necessary, and are preferably 0 to 40% by weight based on the entire PVA resin.

  In addition, as described above, the present invention uses a forming material mainly composed of a PVA-based resin, and the PVA-based resin preferably occupies 80% by weight or more of the entire forming material.

  Examples of components other than the specific PVA resin include, for example, aliphatic polyhydric alcohols such as glycerin, ethylene glycol, and hexanediol, plasticizers such as sugar alcohols such as sorbitol, mannitol, and pentaerythritol, stearic acid amide, Saturated aliphatic amide compounds such as ethylenebisstearic acid amide, unsaturated aliphatic amide compounds such as oleic acid amide, aliphatic metal salts such as calcium stearate, magnesium stearate, zinc stearate, low molecular weight of about 500 to 10,000 Lubricants such as low molecular weight polyolefins such as molecular weight ethylene and low molecular weight propylene, and inorganic acids such as boric acid and phosphoric acid, antioxidants, heat stabilizers, light stabilizers, UV absorbers, colorants, antistatic agents, Surfactant, antiseptic, antibacterial agent, anti-blocking agent, -Up agents, fillers and the like, which are appropriately blended as required.

  Below, the method to manufacture a long-fiber nonwoven fabric (A-2) is demonstrated.

  Examples of the method for producing the long fiber nonwoven fabric (A-2) include a spun bond method and a melt blown method. Especially, since it can manufacture directly from raw material PVA-type resin and is a long fiber, since the nonwoven fabric excellent in intensity | strength is obtained, the spun bond method is used preferably.

  The spunbond method is, for example, melt-kneading a polymer by a melt extruder, guiding the melted polymer to a spinning head and discharging it from a nozzle hole (melt spinning), and cooling the discharged yarn cake with a cooling device Then, using a suction device such as an air jet nozzle, pull it with a high-speed air flow so as to achieve the desired fineness, and then deposit it on a movable collection surface while opening the fiber to form a web. It refers to a method for obtaining a non-woven fabric (A-2) by partially pressing and winding it by heating or the like.

  The melt spinning method is not particularly limited, and the melt spinning is performed from a single nozzle or a composite nozzle using a known melt spinning machine. The spinning temperature is preferably a temperature at which the PVA resin melts and does not deteriorate, and is usually 120 to 230 ° C, particularly 140 to 225 ° C, more preferably 150 to 220 ° C.

  The characteristic of the nonwoven fabric (A) obtained by the manufacturing method of such a long fiber nonwoven fabric (A-2) or the manufacturing method of the short fiber nonwoven fabric (A-1) mentioned above is demonstrated below.

<Characteristics of non-woven fabric (A)>
The basis weight of the obtained non-woven fabric (A) is appropriately set according to its use, but is usually 5 to 500 g / m ² , particularly 10 to 100 g / m ² , and further 20 to 80 g / m ^2. Is preferred. If the basis weight is too small, the absolute amount of PVA fiber is small and the strength is insufficient, and there is a tendency that it is not suitable as a support. On the other hand, if the basis weight is too large, air permeability is lost or nanofibers are not suitable. This is because it tends to be difficult to attach to the nonwoven fabric.

  Moreover, the thickness of the obtained nonwoven fabric (A) is not particularly limited, but is usually 10 to 1000 μm, particularly 20 to 500 μm, and more preferably 30 to 400 μm. If the thickness of the nonwoven fabric (A) is too thick, the flexibility of the nonwoven fabric laminate structure using the nonwoven fabric decreases, and there is a tendency to be inferior in breathability. Conversely, if the thickness is too thin, there is no strength, It is because the tendency which is not suitable as a support body of a nanofiber nonwoven fabric (B) is seen.

  Next, the nanofiber nonwoven fabric (B) will be described.

<< Nanofiber nonwoven fabric (B) with fiber diameter of 1-1000 nm >>
The nonwoven fabric (B) according to the present invention uses a PVA-based resin as a main component, a PVA-based resin nanofiber (hereinafter referred to as “PVA nanofiber”) formed by spinning this material into a fibrous nanofiber. It may be abbreviated).

  The PVA nanofiber is made of a forming material mainly composed of a PVA resin, and the PVA resin is not particularly limited as long as it is a polymer having a vinyl alcohol unit. Similar to the PVA resin used in A-1), for example, a saponified product of not only a partially saponified product or a completely saponified product of polyvinyl acetate but also a copolymer of a vinyl ester and a monomer copolymerizable therewith. Etc. Moreover, the PVA-type resin which has the 1, 2- diol structural unit represented by the said General formula (1) used with the said long-fiber nonwoven fabric (A-2) can also be used. Further, a PVA resin obtained by modifying these PVA resins, for example, an acetoacetyl group-containing PVA into which an acetoacetyl group (hereinafter sometimes abbreviated as “AA group”) is introduced by reacting the PVA resin with diketene. A resin (hereinafter sometimes abbreviated as “AA-modified PVA resin”) may also be used. These may be used alone or in combination of two or more.

  As described above, since the nonwoven fabric (A) and the nanofiber nonwoven fabric (B) are both made of a forming material mainly composed of a PVA-based resin, the difference in shrinkage between the two is small, and in the nonwoven fabric laminated structure obtained thereby, It is possible to prevent the two nonwoven fabrics from being peeled based on the shrinkage rate. Among these, it is preferable to use the same PVA-based resin in the nonwoven fabric (A) and the nanofiber nonwoven fabric (B) from the viewpoint of further reducing the difference in shrinkage rate.

  The average saponification degree of the PVA-based resin used in the nanofiber nonwoven fabric (B) according to the present invention is usually 75 to 100 mol%, particularly 88 to 99.9 mol%, more preferably 95 to 99.9 mol%. Preferably there is. This is because when the average saponification degree is too low, the chemical resistance and solvent resistance of the nonwoven fabric tend to be lowered.

  The average degree of polymerization of the PVA-based resin is preferably 200 to 3000, particularly 300 to 2500, and more preferably 500 to 2300. If the average degree of polymerization is too large, the concentration will be low when the solution viscosity is adjusted to an appropriate viscosity, so that the productivity tends to decrease. This is because the strength of the fiber nonwoven fabric (B) tends to be insufficient.

  It is also possible to use the PVA resin in combination with other water-soluble or water-dispersible resins. Examples of water-soluble or water-dispersible resins that can be used in combination include starch derivatives such as starch, oxidized starch, and cationic modified starch, natural proteins such as gelatin and casein, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose (CMC). ), Cellulose derivatives such as sodium alginate and pectic acid, polyvinylpyrrolidone, water-soluble resins such as poly (meth) acrylate, styrene-butadiene rubber (SBR) latex, nitrile rubber (NBR) latex, Examples thereof include vinyl acetate resin emulsions, ethylene-vinyl acetate copolymer emulsions, (meth) acrylic ester resin emulsions, vinyl chloride resin emulsions and urethane resin emulsions. In the present invention, (meth) acryl means acryl or methacryl.

  In addition, it is preferable to mix an alkali metal salt or an alkaline earth metal salt with the forming material containing a PVA resin as a main component from the viewpoint of further improving melt moldability. Examples of the alkali metal salts include organic acids such as acetic acid such as potassium and sodium, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid and behenic acid, and inorganic acids such as sulfuric acid, sulfurous acid, carbonic acid and phosphoric acid. Metal salts of Examples of the alkaline earth metal salt include organic acids such as calcium, magnesium, acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, behenic acid, sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, and the like. And metal salts of inorganic acids.

  In the above-mentioned forming material, components other than the above include, for example, plasticizers, lubricants, pigment dispersants, thickeners, anti-sticking agents, fluidity improvers, surfactants, antifoaming agents, mold release agents, and penetration agents. Known additives such as agents, dyes, pigments, fluorescent brighteners, ultraviolet absorbers, antioxidants, preservatives, antifungal agents, paper strength enhancers, and crosslinking agents can be appropriately blended.

  Next, the nanofiber nonwoven fabric (B) according to the present invention can be produced, for example, as follows.

<Manufacture of nanofiber nonwoven fabric>
The nanofiber nonwoven fabric (B) can be obtained by applying a PVA resin solution in which a PVA resin is dissolved in a solvent to an electrospinning method (electrostatic spinning method).

  As the solvent, for example, water, alcohols, and other organic solvents can be used. Among these, it is preferable to use water in view of problems in the manufacturing environment.

  As the electrospinning method (electrostatic spinning method), a method of producing fine fibers such as nanofibers from a polymer solution or polymer melt such as the PVA resin solution using a spinning nozzle is generally known. ing. On the other hand, a method not using a spinning nozzle has been recently proposed. Therefore, the method for producing the nanofiber nonwoven fabric (B) according to the present invention will be described by dividing into “method using a spinning nozzle (A)” and “method not using (B)”.

(Electrospinning method using spinning nozzle (a))
Obtaining the nanofiber nonwoven fabric (B) according to the present invention using an electrospinning method using a spinning nozzle is performed, for example, as follows. The nanofiber nonwoven fabric (B), when extruding the PVA resin solution from the spinning nozzle, is applied with a high voltage on the spinning nozzle side and stretched by applying an electric field to the solution to form a nanofiber, It is obtained by depositing nanofibers on the counter electrode side. In addition, a voltage may be applied to the counter electrode side instead of the spinning nozzle side, and an electric field may be applied to the spinning nozzle.

  The concentration of the PVA resin in the solution is usually 1 to 40% by weight, particularly 2 to 30% by weight, more preferably 5 to 20% by weight, but is not particularly limited, and is arbitrarily Can be set.

  The direction of extrusion of the solution is not particularly limited, but it is preferable that the direction of extrusion from the nozzle and the direction of action of gravity do not coincide with each other so that the solution does not easily drop. In particular, it is preferable to extrude the solution in a direction opposite to the direction of gravity or in a direction perpendicular to the direction of gravity.

  The diameter (inner diameter) of the spinning nozzle for extruding this solution varies depending on the fiber diameter, but is usually 0.1 to 5 mm, in particular, so that the nanofiber having a fiber diameter of 1 to 1000 nm according to the present invention can be obtained. It is preferable that it is 0.5-2 mm. This is because if the diameter is too large, there is a tendency for liquid dripping to be difficult, and electrospinning tends to be difficult. Conversely, if the diameter is too small, it is difficult to extrude the solution and productivity tends to decrease.

  The spinning nozzle may be made of metal or non-metal. If the spinning nozzle is made of metal, the spinning nozzle can be used as one electrode. If the spinning nozzle is made of non-metal, an electric field is applied to the solution by installing an electrode inside the spinning nozzle. Can act.

  After extruding the solution from such a spinning nozzle, the solution is drawn into fiber by applying an electric field to the extruded solution. This electric field varies depending on the fiber diameter of the nanofiber, the distance between the spinning nozzle and the collector for collecting the nanofiber, the viscosity of the solution, and the like, but is not particularly limited, but the nanofiber according to the present invention. Is preferably 0.2 to 5 kV / cm. If the electric field to be applied is large, the fiber diameter of the nanofiber tends to be reduced according to the increase in the electric field value, but if the electric field value is too large, air breakdown tends to occur, conversely, This is because if it is too small, it tends to be difficult to form a fiber.

  By applying an electric field to the thus-dissolved solution, an electrostatic charge is accumulated in the solution, and is electrically pulled by the collector-side electrode, and is stretched to be fiberized. Since the fibers are electrically stretched, the speed of the fibers is accelerated by the electric field as the fibers approach the collector, resulting in a PVA resin fiber having a smaller fiber diameter. Further, it is considered that the PVA resin fiber becomes thinner due to evaporation of the solvent, the electrostatic density is increased, it is split by the electric repulsive force, and the fiber diameter is further reduced.

  Such an electric field provides, for example, a potential difference between the spinning nozzle (the nozzle itself in the case of a metal nozzle, or the electrode inside the nozzle in the case of a non-metallic nozzle such as glass or resin) and the collector. It can be made to act. For example, a potential difference can be provided by applying a voltage to the spinning nozzle and grounding the collector, and conversely, a potential difference can be provided by applying a voltage to the collector and grounding the spinning nozzle.

  The applied voltage is not particularly limited as long as the electric field intensity can be set as described above, but is usually 1 to 30 kV, particularly 5 to 20 kV, and more preferably 10 to 20 kV. If the voltage is too high, sparks tend to be generated and spinning becomes impossible. Conversely, if the voltage is too low, the force for electrically pulling the solution is insufficient and spinning tends to be difficult. This is because of The voltage application device is not particularly limited, but a direct current high voltage generator can be used, and a Van de Graf electromotive machine can also be used.

  Note that the polarity of the applied voltage may be either positive or negative. However, it is preferable to set the spinning nozzle side to have a positive potential so that the fiber can be prevented from spreading and gathered in a state where the pore diameter is small and the pore diameter distribution is narrow. In particular, it is preferable that the counter electrode on the collector side is grounded and the spinning nozzle side is applied positively so that the spinning nozzle side becomes a positive potential so that corona discharge during voltage application can be easily suppressed.

  In the present invention, the PVA nanofibers formed as described above are deposited to form a nonwoven fabric. The collector to which the PVA nanofibers are deposited is not particularly limited as long as the PVA nanofibers can be collected. For example, a conductive material made of metal or carbon, a non-conductive material made of an organic polymer, or the like having a drum, non-woven fabric, flat plate, or belt shape can be used. Usually, the nonwoven fabric (A) described above is used as a collector. If the collector is a non-woven fabric (A), the fibers of the nanofiber non-woven fabric (B) enter the voids of the non-woven fabric (A), so that the two are intertwined with each other and become more excellent in peel resistance. It is.

  The collector does not need to be a conductive material as described above, and the counter electrode may be disposed behind the collector. In this case, the collector and the counter electrode may be in contact with each other or may be separated from each other.

  This electrospinning method is preferably carried out in an atmosphere with a relative humidity of usually 30 to 80%, particularly 35 to 70%. If the relative humidity is too low, the solution is dried quickly at the spinning nozzle outlet and tends to solidify and block the nozzle. If the relative humidity is too high, the fiber is formed, which is difficult to dry. This is because it tends to be difficult to do.

  In order to maintain the above relative humidity, the spinning nozzle and the collection body are installed in a sealed container, and the conditioned air is fed through a valve or the like so that the humidity in the sealed container can be adjusted within the above range. It is preferable. In addition, it is preferable that the exhaust device is connected to the sealed container so that the pressure in the sealed container is not increased and the solvent volatilized from the solution can be discharged.

<Electrospinning method without spinning nozzle (b)>
As an electrospinning method that does not use a spinning nozzle, for example, a method in which a magnetic fluid is used as an electrode and electrostatic spinning is performed from the surface of a PVA-based resin solution (AL Yarin, E. Zussman, “Polymer”, 45 (2004) 2977-2980). Also, as an electrospinning method, a rotating roll is immersed in a bath filled with a PVA resin solution, a PVA resin solution is adhered on the roll surface, a high voltage is applied to the surface, and electrostatic spinning is performed. (See http://www.elmarco.com), and a method of performing electrospinning by applying a high voltage to bubbles continuously generated in the PVA resin solution. (See “NONWOVENS REVIEW”, Vol. 18, No. 2 (2007) 17-20, Japanese Patent Laid-Open No. 2008-25057).

  Next, the characteristics of the nanofiber nonwoven fabric (B) obtained by the methods (a) and (b) will be described.

<Characteristics of nanofiber nonwoven fabric (B)>
The fiber diameter of the PVA nanofibers constituting the nanofiber nonwoven fabric (B) according to the present invention is 1-1000 nm. In particular, it is 5 to 500 nm, more preferably 10 to 300 nm. This is because if the fiber diameter is too large, the filter effect of the nanofiber nonwoven fabric (B) obtained from this fiber is lowered, or the air permeability is lowered. Moreover, when the fiber diameter is too thin, the strength of the nanofiber nonwoven fabric (B) is lowered, or the production efficiency is lowered. Furthermore, when a fiber diameter remove | deviates from the said range, the tendency for the coupling | bonding between fibers with a nonwoven fabric (A) will become weak. The fiber diameter of such nanofibers can be measured using an electron microscope.

  The average fiber length of the nanofiber is not particularly limited, but is preferably 0.1 mm or more, and particularly preferably a continuous fiber, from the viewpoint of preventing the nanofiber from falling off.

The basis weight of the obtained nanofiber nonwoven fabric (B) is appropriately set depending on the use, but is usually 0.1 to 40 g / m ² , particularly 0.5 to 20 g / m ² , and further 1 It is preferably 10 to 10 g / m ² . This is because if the basis weight is too small, the filter effect tends to decrease, and conversely if too large, the production efficiency tends to decrease.

  Moreover, it is preferable that the thickness of a nanofiber nonwoven fabric (B) is 0.1-500 micrometers normally, Especially 0.3-300 micrometers, Furthermore, it is preferable that it is 0.5-100 micrometers. This is because if the thickness is too thick, the production efficiency tends to decrease, whereas if the thickness is too thin, the filter effect tends to be insufficient.

  Using the nonwoven fabric (A) and nanofiber nonwoven fabric (B) obtained as described above, a nonwoven fabric laminated structure is produced as follows.

<< Non-woven fabric laminated structure >>
The nonwoven fabric laminate structure formed by laminating the nonwoven fabric (A) and the nanofiber nonwoven fabric (B) may be produced by separately preparing the nonwoven fabric (A) and the nanofiber nonwoven fabric (B) and laminating them. Although it is good, normally, it is made into a nonwoven fabric laminated structure by using a nonwoven fabric (A) as a collection object at the time of manufacturing a nanofiber nonwoven fabric (B). In this case, as described above, since the nanofiber nonwoven fabric (B) enters the voids of the nonwoven fabric (A), both are in a state of being entangled with each other. Become better.

  The thickness ratio (A / B) between the nonwoven fabric (A) and the nanofiber nonwoven fabric (B) is usually 1/50 to 10000/1, particularly 1/2 to 800/1, more preferably 1/1 to 100 /. 1 is preferable. This is because when the nonwoven fabric (A) is too thin compared to the nanofiber nonwoven fabric (B), the strength of the resulting nonwoven fabric laminate structure tends to be insufficient.

  If necessary, various post-treatments can be performed so that the nonwoven fabric laminated structure is suitable for various applications. Examples of the post-treatment include calender treatment for densification, hydrophilic treatment, water repellent treatment, sea surface active agent adhesion treatment, and pure cleaning treatment.

  Moreover, as laminated structure of the obtained nonwoven fabric laminated structure, not only B / A (laminated body which consists of A and B) illustrated by FIG. 1, but A / B / A, B / A / B / A, etc. , A and B may be sequentially laminated.

  Furthermore, not only A and B but other layers may be laminated. Examples of other layers include woven fabrics, nets, wire nets, and papers made of various thermoplastic resins.

  When the obtained nonwoven fabric laminated structure of the present invention is used as a filter or the like, the flow direction of gas or liquid can be caused to flow from the nanofiber nonwoven fabric (B) side to the nonwoven fabric (A) side, thereby further peeling. It is preferable from the point which can prevent.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “parts” and “%” mean weight basis unless otherwise specified.

[Example 1]
First, the nonwoven fabric (A) which is a support body is produced, and the nanofiber nonwoven fabric (B) is laminated on the nonwoven fabric (A). This will be described in order below.

<1. About non-woven fabric (A)>
<1-1. Production of PVA resin (a) used for nonwoven fabric (A)>
First, 2700 g of vinyl acetate, 240 g of 3,4-diacetoxy-1-butene, 800 g of methanol, and 0.05 mol% of azobisisobutyronitrile (vs. vinyl acetate charged) are prepared. After charging a total amount of vinyl acetate, 10% of 3,4-diacetoxy-1-butene, and all amounts of methanol and azobisisobutyronitrile into a reaction vessel equipped with a reflux condenser, a dropping funnel and a stirrer. While stirring, the temperature was raised under a nitrogen stream to initiate polymerization, and the remainder (90%) of 3,4-diacetoxy-1-butene was added dropwise at a constant rate over 9 hours. When the polymerization rate of vinyl acetate reached 87%, a predetermined amount of m-dinitrobenzene was added to complete the polymerization, and then unreacted vinyl acetate monomer was removed from the system by blowing methanol vapor. A methanol solution of the copolymer was obtained.

  Next, the obtained solution was diluted with methanol, adjusted to a concentration of 35%, charged into a kneader, and a 2% methanol solution of sodium hydroxide was added to the vinyl acetate structure in the copolymer while keeping the solution temperature at 40 ° C. Saponification was carried out by adding 8 mmol per 1 mol of the total amount of the unit and 3,4-diacetoxy-1-butene structural unit. When saponification progresses and saponification precipitates and forms particles, it is filtered, washed well with methanol, and dried in a hot air dryer to have the desired 1,2-diol structural unit. A PVA resin (a) was produced.

The degree of saponification of the obtained PVA resin (a) having the 1,2-diol structural unit was analyzed based on the alkali consumption required for hydrolysis of residual vinyl acetate and 3,4-diacetoxy-1-butene. However, it was 98.5 mol%. Moreover, the average degree of polymerization was 300 when analyzed according to JIS K 6726. The content of the 1,2-diol structural unit represented by the formula (1a) was 8.0 mol% when calculated by measurement with ¹ H-NMR (internal standard substance; tetramethylsilane). It was. And the melting | fusing point was 170 degreeC.

  Next, the PVA resin (a) having the 1,2-diol structural unit was used as a fiber-forming material for the production of the nonwoven fabric (A).

<1-2. Production of non-woven fabric (A)>
The non-woven fabric (A) is first formed into a melt-extruded pellet at a resin temperature of 190 ° C. under the following conditions using the PVA resin (a) as a material and using a twin screw extruder. Then, the pellets are used in a spunbond nonwoven fabric production apparatus to produce a nonwoven fabric (A) under the following conditions I) and II).

I) Pelletization conditions-Equipment: 58φ twin screw extruder (Toshiba Machine Co., Ltd., TEM58BS-46)
-Temperature conditions: C1 / C2 / C3 / C4 / C5 / C6 / C7 / C8 / C10 / H = 80/180/190/190/190/190/190/190/190/190 ° C. C10 represents a kneading part of the extruder, specifically, from a portion close to the hopper, C1 to C10, and H represents a head part.)
・ Other conditions: Air-cooled belt, pelletizer

II) Non-woven fabric conditions ・ Single screw extruder: Screw diameter φ65mm, L / D = 30
-Temperature conditions: C1 / C2 / C3 / C4 / C5 / die = 190/190/195/195/190/190 ° C. (where C1 to C5 indicate the kneading part of the extruder, specifically, a hopper (From the part near to C1 to C5, and the die indicates a die part.)
-Filter: Nozzle pack filter (200 mesh + 350 mesh + 60 mesh + 30 mesh + 20 mesh)
・ Nozzle: φ0.5 mm, 501 holes, staggered arrangement ・ Discharge amount: 0.72 g / min. ・ Hole roll: Using an embossing roll (100 ° C.) and a flat roll (100 ° C.) having a concavo-convex pattern on the surface The non-woven fabric is partially heat-sealed by thermocompression bonding with a linear pressure of 40 kg / cm.

The obtained nonwoven fabric (A) had a fiber diameter of 17 μm on average, a basis weight of 40 g / m ² , and a thickness of 250 μm.

<2. About nanofiber nonwoven fabric (B)>
<2-1. PVA resin (b1) used for nanofiber nonwoven fabric (B)>
As a PVA resin used for the nanofiber nonwoven fabric (B), an unmodified PVA resin (b1) having a polymerization degree of 1100 and a saponification degree of 98.5 mol% was prepared. Next, this unmodified PVA-based resin was dissolved to a concentration of 10% while being heated with pure water to prepare a PVA aqueous solution.

<2-2. Production of Nanofiber Nonwoven Fabric (B) and Nonwoven Fabric Laminated Structure>
Next, the PVA aqueous solution obtained above is applied to a nozzle under the conditions of the following III), an electric field is applied to the extruded PVA aqueous solution to form nanofibers, and the nonwoven fabric (A) as a support: On top of this, PVA nanofibers were deposited to form a nanofiber nonwoven fabric (B) to produce a nonwoven fabric laminate structure.

III) Conditions for making nanofibers ・ Device: Electrostatic spinning device (Kato Tech Co., Ltd.)
Manufacturing conditions: Voltage 20 kV, nozzle diameter 1.2 mm, number of nozzles 9
・ Distance between targets: 7cm

The obtained nanofiber nonwoven fabric (B) had a fiber diameter of 200 nm in average diameter, a basis weight of 5 g / m ² , and an average thickness of 20 μm.

<3. About the obtained non-woven laminate structure>
The nonwoven fabric laminated structure obtained as described above had a total basis weight of 45 g / m ² and a total thickness average of 270 μm.

[Example 2]
In Example 1, instead of the unmodified PVA resin (b1) used for the production of the nanofiber nonwoven fabric (B), an AA-modified PVA resin (b2) obtained by the following production method was used. In the same manner as in Example 1, a nonwoven fabric laminated structure having a total basis weight of 45 g / m ² and a total thickness average of 270 μm was produced.

<Manufacture of AA-ized PVA resin (b2)>
A ribbon blender with a temperature controller was charged with 100 parts of an unmodified PVA resin (saponification degree 95.1 mol%, average polymerization degree 1100), heated to 60 ° C. while stirring at a rotation speed of 20 rpm, and 30 parts of acetic acid. Was added over 90 minutes, and the mixture was further stirred for 1 hour to swell the PVA resin. To this, 29.2 parts of diketene was added by spraying over 8 hours, and the reaction was further continued for 30 minutes. After completion of the reaction, 300 parts of methanol was added, and after solid-liquid separation, it was further washed twice with methanol at an extractant ratio of 3 times and dried at 60 ° C. to obtain an AA-PVA-based resin (b2).

  Total acetoacetyl group content (hereinafter abbreviated as “AA conversion degree”) in the obtained AA-modified PVA resin (b2) was 7.9 mol%, and the saponification degree was 95.1 mol%. The average degree of polymerization was 1200.

[Comparative Example 1]
A total basis weight of 45 g / m ² and a total thickness average of 270 μm were obtained in the same manner as in Example 1 except that polypropylene (PP) was used instead of the PVA-based resin that is the forming material of the nonwoven fabric (A) of Example 1. A non-woven laminate structure was produced.

[Comparative Example 2]
A total basis weight of 45 g / m ² and a total thickness average of 270 μm were obtained in the same manner as in Example 2 except that polypropylene (PP) was used instead of the PVA-based resin that is the forming material of the nonwoven fabric (A) of Example 2. A non-woven laminate structure was produced.

The PP spunbond nonwoven fabric (A) obtained in Comparative Examples 1 and 2 had a fiber diameter of 20 μm on average, a basis weight of 40 g / m ² , and a thickness of 250 μm.

  The PVA resins used in the examples and comparative examples are shown in Table 1 below. And using the obtained nonwoven fabric laminated structure, peeling resistance was evaluated by the following method, and the results are shown in Table 1 below.

<Peeling resistance>
The non-woven laminate structure was stored at 30 ° C. and 70% RH for 10 days, and then the peel distance from the periphery was measured and evaluated according to the following criteria.
O: 0 to less than 1 mm.
X: 1 mm or more.

  From the above results, it can be seen that all of the examples are excellent in peel resistance. This is because not only the nanofiber non-woven fabric (B) but also the non-woven fabric (A) is made of PVA resin fibers, so that the shrinkage rate of both non-woven fabrics approximates and peeling due to the difference in shrinkage rate decreases. It is believed that there is.

  On the other hand, the comparative example is considered to have resulted in inferior peel resistance because the constituent components are different between the nonwoven fabric (A) and the nanofiber nonwoven fabric (B), and the shrinkage is also different.

  The nonwoven fabric laminated structure of the present invention is, for example, an air purifier filter, an industrial dust removal filter, a filter for purifying pure water and chemicals, a medical / medical filter, a battery separator, etc. It can be used for high-precision filters and separators that are thinner, have a uniform basis weight, and have high strength.

It is sectional drawing which shows an example of the nonwoven fabric laminated structure of this invention.

Explanation of symbols

1 PVA nonwoven fabric (A)
2 PVA nanofiber nonwoven fabric (B)

Claims (3)

  A nonwoven fabric laminate structure in which a nonwoven fabric (A) composed of fibers having a fiber diameter of 5 to 100 μm and a nanofiber nonwoven fabric (B) composed of nanofibers having a fiber diameter of 1 to 1000 nm are laminated, the nonwoven fabric (A) and A nonwoven fabric laminated structure, wherein the nanofiber nonwoven fabric (B) is a nonwoven fabric made of polyvinyl alcohol resin fibers. The nonwoven fabric laminate structure according to claim 1, wherein the nonwoven fabric (A) is a spunbond nonwoven fabric containing a polyvinyl alcohol-based resin containing a structural unit represented by the following general formula (1).

  A method for producing a nonwoven fabric laminate structure according to claim 1 or 2, wherein when the nanofibers are deposited on a nanofiber collector to form a nanofiber nonwoven fabric, A method for producing a laminated structure of a nonwoven fabric, characterized in that a laminated structure with the nonwoven fabric (A) is produced simultaneously with the production of the nanofiber nonwoven fabric (B) using the nonwoven fabric (A).

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