JP2012040730A - Laminated nonwoven fabrics, and wiper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide laminated nonwoven fabrics having a water-absorbing property and high flexibility, which floats on water.SOLUTION: The laminated nonwoven fabrics include: a top layer formed of a nonwoven fabric containing hydrophilic fibers; a back layer formed of a nonwoven fabric containing hydrophobic fibers; and an adhesive layer intervening between the top layer and the back layer. A ratio of a weight per unit area of the top layer to a total sum of a weight per unit area of the back layer and a basis weight is adjusted between a range of 55/45 to 40/60. The laminated nonwoven fabrics may have a water-absorbing property of ≥200% and a surface water-absorbing speed of ≤10 s. The laminated nonwoven fabrics have the basis weight of 60 to 100 g/mand a thickness of 0.40 to 0.65 mm, and may have an apparent density of 0.1 to 0.2 g/m. The laminated nonwoven fabrics can be employed for a wiper used for cleaning of a tub or tank filled with water.

Description

  The present invention relates to a laminated nonwoven fabric and a wiper used for wiping a tank or a tank filled with water in a nuclear power plant core or peripheral equipment.

  Many wipers have been proposed for wiping, but all of them are made of a material with high water absorption. Furthermore, as such a wiper, a nonwoven fabric composed of hydrophilic fibers is widely used because of its high productivity and excellent water absorption. On the other hand, a wiper with high water absorption has high water absorption and excellent wiping properties, but has a feature that when the wiper falls on the water surface, it sinks into water. Even if the wiper is submerged in water, it will not be a problem when used in general households. However, if the wiper is used for cleaning water tanks and water tanks in factory facilities, it may fall due to human error. The wiper sinks at the bottom of the water tank or tank, making recovery difficult. In particular, water tanks and tanks at nuclear power plants are highly dangerous and require strict management.For example, if a wiper used around a spent fuel pool or cavity sinks and becomes a foreign object, a major accident is induced. There is a risk of doing. Therefore, a wiper that has a high wiping property and does not sink in water has been proposed.

  In Japanese Utility Model Publication No. 6-66553 (Patent Document 1), a square-shaped waste made of a waste material such as cotton fiber is wrapped with a triangular float material made of foamed polyethylene at one corner and sewn. A waste is disclosed. However, this wiper has good water absorption and has foamed polyethylene at one corner, so that the flexibility of the wiper is uneven and the cleaning workability is low.

Japanese Utility Model Laid-Open No. 6-66553 (Scope of Claim for Utility Model Registration, Detailed Explanation of Invention, Fig. 1)

  Accordingly, an object of the present invention is to provide a laminated nonwoven fabric that has water absorption, high flexibility, and floats on water, and a wiper formed of the laminated nonwoven fabric.

  Another object of the present invention is to provide a laminated nonwoven fabric excellent in cleaning workability, handleability and durability as a wiper, which floats on the water surface even when dropped in a water tank and is easily collected, and a wiper formed of this laminated nonwoven fabric. There is.

  As a result of earnest studies to achieve the above-mentioned problems, the inventors laminated a nonwoven fabric containing hydrophilic fibers and a nonwoven fabric containing non-hydrophilic fibers via an adhesive layer, and adjusted the basis weight of each layer. The present invention has been completed by finding that a nonwoven fabric having water absorption and high flexibility can be obtained despite floating.

That is, the laminated nonwoven fabric of the present invention includes a surface layer formed of a nonwoven fabric containing hydrophilic fibers, a back layer formed of a nonwoven fabric containing non-hydrophilic fibers, and an adhesive interposed between the surface layer and the back layer. The ratio of the basis weight of the surface layer to the total basis weight of the back layer and the adhesive layer is the former / the latter = 55/45 to 40/60. The nonwoven fabric of the surface layer may contain 50% by mass or more of hydrophilic fibers, and particularly may contain 10 to 50 parts by mass of non-hydrophilic fibers with respect to 100 parts by mass of hydrophilic fibers. In the nonwoven fabric of the surface layer, the hydrophilic fiber may contain a cellulosic fiber, and the non-hydrophilic fiber may contain a polyolefin fiber. In particular, the hydrophilic fiber may be a cellulosic fiber and a polyester fiber having a hydrophilic surface, and the non-hydrophilic fiber is a core portion made of a polypropylene resin and a sheath portion made of a polyethylene resin. The core-sheath type polyolefin fiber which consists of may be sufficient. The surface nonwoven fabric may be a hydroentangled nonwoven fabric. The nonwoven fabric of the back layer may be composed of polyolefin fibers and / or polyester fibers. The nonwoven fabric of the back layer may be made of polypropylene fibers, and the apparent density of the laminated nonwoven fabric may be 0.5 g / cm ³ or less. The adhesive layer may be formed of a nonwoven fabric composed of polyethylene fibers having a melting point lower than that of the fibers constituting the surface layer and the back layer. The ratio of the basis weight of the surface layer to the basis weight of the adhesive layer may be the former / the latter = 90/10 to 50/50. The laminated nonwoven fabric of the present invention may have a water absorption rate of 200% or more, and a surface layer surface water absorption rate in accordance with the dropping method of JIS L1907-7.1.1 may be 10 seconds or less. In the laminated nonwoven fabric of the present invention, the ratio of the hydrophilic fibers to the non-hydrophilic fibers (mass ratio) in the whole laminated nonwoven fabric may be the former / the latter = 20/80 to 50/50. The laminated nonwoven fabric of the present invention may have a basis weight of 60 to 100 g / m ² , a thickness of 0.40 to 0.65 mm, and an apparent density of 0.1 to 0.2 g / cm ^3. . The laminated nonwoven fabric of the present invention may have a true density (true specific gravity) larger than water (1 g / cm ³ ). In the laminated nonwoven fabric of the present invention, each layer may be thermally bonded by embossing. The laminated nonwoven fabric of the present invention was filled with 100 liters of water in a cylindrical tank of φ500 mm, a 20 cm × 20 cm square laminated nonwoven fabric was placed on the water surface, and stirred for 2 minutes at 90 rpm with a φ25 mm pipe-like material. After 10 minutes, it floats on the water surface.

  The present invention also includes a wiper composed of the laminated nonwoven fabric. This wiper may be used for cleaning a tank or tank filled with water.

In the present invention, a nonwoven fabric containing hydrophilic fibers and a nonwoven fabric containing non-hydrophilic fibers are laminated via an adhesive layer, and the ratio between the basis weight of the surface layer and the total basis weight of the back layer and the adhesive layer is as follows: Since the former / the latter is adjusted to 55/45 to 40/60, it floats in water despite being a non-woven fabric having water absorption and high flexibility. In particular, it is possible to prepare a wiper that floats on water even when the true density of the laminated nonwoven fabric is greater than that of water because a fine air phase or a cellular phase is held between the fiber structures of the nonwoven fabric, and high wiping properties can be maintained. . Furthermore, if the nonwoven fabric of the back layer is made of polyolefin fibers having a true specific gravity of less than 1 g / cm ³ , the wiper can be reliably prevented from settling or sinking. Therefore, when used as a wiper, the wiping property is high and there is no delamination between layers, so that it is excellent in cleaning workability, handling property and durability, and even if it falls into a water tank, it floats on the water surface and is easy to collect. Therefore, it is suitable for applications where the sinking of wipers becomes a problem, such as water tanks and tanks in nuclear power plants.

[Laminated nonwoven fabric]
The laminated nonwoven fabric of the present invention is characterized by floating in water, and is formed of a surface layer formed of a nonwoven fabric (nonwoven fiber assembly) containing hydrophilic fibers and a nonwoven fabric (nonwoven fiber assembly) containing non-hydrophilic fibers. And the ratio of the basis weight of the surface layer to the total basis weight of the back layer and the adhesive layer is the former / The latter is adjusted to 55/45 to 40/60.

(Surface)
The surface layer has water absorption and has a role as a wiping layer (wiping layer) when used as a wiper. The surface layer is formed of a nonwoven fabric containing hydrophilic fibers in order to develop water absorption.

  The hydrophilic fiber is not particularly limited as long as it has hydrophilicity, and a synthetic fiber, a natural fiber, a natural plant fiber, an animal protein fiber, etc. are dissolved once and then chemically treated to produce a fiber. Fiber etc. can be selected. Furthermore, the hydrophilic fiber only needs to have at least a surface composed of a hydrophilic resin or a hydrophilic component. For example, the hydrophilic fiber is a composite fiber in which the surface of the fiber is hydrophilized or the surface of the fiber is covered with a hydrophilic resin. May be.

  Synthetic fibers include, for example, resins having hydrophilic groups (particularly hydroxyl groups) such as hydroxyl groups, carboxyl groups, sulfonic acid groups, and ether bonds in the molecule, such as polyesters such as polyvinyl alcohol resins, polyamide resins, and polylactic acid. And synthetic fibers composed of a resin, a (meth) acrylic copolymer containing a (meth) acrylamide unit, and the like. These synthetic fibers can be used alone or in combination of two or more. Among these synthetic fibers, a hydrophilic resin having a hydroxyl group in the monomer unit is preferable, and a fiber composed of an ethylene-vinyl alcohol copolymer is particularly preferable from the viewpoint of having a hydroxyl group uniformly in the molecule.

  In the ethylene-vinyl alcohol copolymer, the ethylene unit content (copolymerization ratio) is, for example, about 10 to 60 mol%, preferably about 20 to 55 mol%, and more preferably about 30 to 50 mol%. The saponification degree of the vinyl alcohol unit is, for example, about 90 to 99.99 mol%, preferably 95 to 99.98 mol%, more preferably about 96 to 99.97 mol%. The viscosity average degree of polymerization is, for example, about 200 to 2500, preferably about 300 to 2000, and more preferably about 400 to 1500. As will be described later, when a wet heat adhesive resin such as an ethylene-vinyl alcohol copolymer is used, a bulky and stable liquid retaining layer can be formed by a steam jet method.

  Examples of natural fibers include cotton or cotton, silk, hemp, silk, wool, and the like. These natural fibers can be used alone or in combination of two or more. Of these, cotton is widely used.

  Examples of the regenerated fiber include rayon such as viscose rayon, cellulose such as tencel such as acetate and lyocell, cupra and polynosic. These natural fibers can be used alone or in combination of two or more. Of these, rayon fibers and tencel fibers are widely used.

  In a composite fiber whose surface is composed of a hydrophilic resin or a hydrophilic component, as a method of imparting hydrophilicity to the fiber surface, a method of forming a hydrophilic layer by treating the fiber surface with a hydrophilizing agent, fiber forming property A method may be used in which a hydrophilic resin is fiberized together with the resin, and at least a part of the fiber surface is covered with the hydrophilic resin.

In the method of forming a hydrophilic layer by treating with a hydrophilizing agent, a nonionic surfactant is widely used as the hydrophilizing agent, for example, polyoxyethylene alkyl ether (for example, polyoxyethylene octyl ether, polyoxyethylene lauryl ether). , Polyoxyethylene C _6-24 alkyl ethers such as polyoxyethylene cetyl ether), polyoxyethylene alkyl phenyl ethers (for example, polyoxyethylene C _6-18 such as polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether) alkyl phenyl ether, etc.), polyoxyethylene polyhydric alcohol fatty acid partial esters [e.g., polyoxyethylene glycerin C _8-24 fatty such as polyoxyethylene glycerin stearic acid ester Esters, polyoxyethylene sorbitan C _8-24 fatty acid esters such as polyoxyethylene sorbitan stearic acid ester, and polyoxyethylene sucrose C _8-24 fatty acid esters, polyglycerol fatty acid esters (e.g., polyglycerol monostearate, etc. Polyglycerin C _8-24 fatty acid ester). The hydrophilizing agent may be an oil agent used in the spinning process from the viewpoint of productivity and the like, and the fiber surface may be hydrophilized by selecting a hydrophilic oil agent as the spinning oil agent. The ratio of the hydrophilizing agent is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, more preferably 0.1 to 3 parts by mass (particularly 0.2 parts) with respect to 100 parts by mass of the fiber. (About 2 parts by mass).

  The method of covering the surface of the fiber with the hydrophilic resin may be a method of covering the entire surface of the fiber with a hydrophilic resin in a sheath shape. The composite fiber of the core-sheath type structure obtained by this method is covered with a hydrophilic resin in the form of a sheath, so that there is little deterioration in hydrophilic performance even when used for a long time. The method of fiberizing a hydrophilic resin together with a fiber-forming resin can impart a uniform high hydrophilicity while shortening the production process. The hydrophilic resin in the sheath is preferably a resin constituting a synthetic fiber, particularly a polyvinyl alcohol resin such as an ethylene-vinyl alcohol copolymer, because a bulky and stable nonwoven fabric can be produced. In the core-sheath type composite fiber, the ratio between the core part and the sheath part (mass ratio) is, for example, sheath part / core part = 90/10 to 10/90 (for example, 60/40 to 10/90), preferably It is about 80/20 to 15/85, more preferably about 60/40 to 20/80.

  The fiber used for the treatment with the hydrophilizing agent or the coating with the hydrophilic resin may be a hydrophilic fiber or a non-hydrophilic fiber. Of these, non-hydrophilic fibers such as polypropylene resins, polyester resins, polyamide resins, etc. are preferred because of their high durability and strong stiffness as wiper wiping layers. Polyester fibers such as polyethylene terephthalate fibers are particularly preferred from the viewpoint of excellent balance.

  Of these hydrophilic fibers, cellulose fibers such as natural cellulosic fibers such as cotton, regenerated cellulosic fibers such as rayon and tencel, and the like are preferable because of their high water absorption performance and excellent wipeability as a wiper. These cellulosic fibers can be used alone or in combination of two or more.

  Further, the cellulosic fiber may be combined with the above-mentioned composite fiber (particularly, a polyester fiber having a hydrophilic surface). The proportion of the composite fiber may be, for example, 100 parts by mass or less with respect to 100 parts by mass of the cellulosic fiber, for example, 10 to 90 parts by mass, preferably 30 to 80 parts by mass, and more preferably 50 to 70 parts. About mass parts.

  The surface layer may further contain non-hydrophilic fibers (fibers that are not so high in polarity and relatively strong in hydrophobicity) from the viewpoint of improving the adhesion to the adhesive layer. Non-hydrophilic fibers include, for example, polyolefin fibers (for example, polyethylene fibers, polypropylene fibers, polybutene fibers, polymethylpentene fibers), polyester fibers (for example, polyethylene terephthalate fibers, polybutylene terephthalate fibers), and polyamide fibers. Examples thereof include fibers (for example, polyamide 6 fibers, polyamide 66 fibers, etc.), polyurethane fibers (for example, polyester polyol type urethane fibers, etc.), and the like. Of these, polyolefin fibers are preferred because of their high hot melt adhesiveness and low specific gravity.

  Polyolefin fiber has a certain degree of hot-melt adhesiveness, can improve adhesion to the adhesive layer, and maintain fiber form even when heated for adhesion to the adhesive layer, and from the point of maintaining wiping properties Particularly preferred is a core-sheath type polyolefin fiber comprising a core part composed of a polypropylene resin (particularly polypropylene) and a sheath part composed of a polyethylene resin (particularly polyethylene).

The polypropylene resin that constitutes the core is a copolymerizable monomer (for example, α-C _2-12 olefin monomer such as ethylene, butene, pentene, methylpentene, hexene, octene, (meth) Acrylic monomers such as acrylic acid and (meth) acrylic acid alkyl ester) may be included. The ratio of the other copolymerizable monomer is, for example, 10 mol% or less, preferably 5 mol% or less.

Polyethylene resins constituting the sheath are also other copolymerizable monomers (for example, α-C _3-12 olefin monomers such as propylene, butene, pentene, methylpentene, hexene, octene, (meth) Acrylic monomers such as acrylic acid and (meth) acrylic acid alkyl ester) may be included. The ratio of the other copolymerizable monomer is, for example, 10 mol% or less, preferably 5 mol% or less.

  The ratio (mass ratio) between the core portion and the sheath portion is, for example, sheath / core = 90/10 to 10/90 (for example, 60/40 to 10/90), preferably 80/20 to 15/85. More preferably, it is about 60/40 to 20/80.

  The melting point of the polyolefin fiber is preferably higher than the melting point of the fiber constituting the adhesive layer, and is, for example, 110 ° C. or higher, preferably 115 to 200 ° C., more preferably about 118 to 150 ° C. In particular, in the case of the core-sheath conjugate fiber, the melting point of the polyethylene resin constituting the sheath part is a melting point that melts at a temperature for heat-bonding with the adhesive layer when the adhesive layer is formed of a hot-melt adhesive resin. For example, it may be about 110 to 130 ° C, preferably about 115 to 125 ° C. When the melting point of the polyethylene resin is about the same as the heat treatment temperature, the resin melts appropriately and adheres to the adhesive layer, and the core formed of the polypropylene resin maintains the fiber shape, so that the wiping property can also be maintained.

  The ratio of the hydrophilic fiber should just be 50 mass% or more with respect to the whole surface layer, for example, 50-100 mass%, Preferably it is 60-95 mass%, More preferably, it is 65-90 mass% (especially 70-90 mass%). 85 mass%).

  The ratio of the non-hydrophilic fiber is, for example, 10 to 50 parts by mass, preferably 15 to 45 parts by mass, more preferably 20 to 40 parts by mass (particularly 30 to 40 parts by mass) with respect to 100 parts by mass of the hydrophilic fiber. Degree.

  Each fiber constituting the surface non-woven fabric is further added with conventional additives such as stabilizers (heat stabilizers such as copper compounds, UV absorbers, light stabilizers, antioxidants, etc.), dispersants, fine particles, and coloring. Agents or extender pigments (such as titanium oxide), antistatic agents, flame retardants, plasticizers, lubricants, crystallization rate retarders, lubricants, antibacterial agents, insect and acaricides, fungicides, matting agents, heat storage agents, A fragrance, a fluorescent brightening agent, a wetting agent and the like may be contained. These additives can be used alone or in combination of two or more. These additives may be carried on the surface of the surface layer or may be contained in the fiber. The ratio of these additives is, for example, 30% by mass or less (for example, 0 to 30% by mass), preferably 0.01 to 20% by mass, and more preferably 0.1 to 10% by mass with respect to the entire nonwoven fabric. It may be a degree.

  The cross-sectional shape of each fiber is not particularly limited. For example, a round cross-section, an irregular cross-section (flat shape, elliptical cross-section, etc.), a polygonal cross-section, a multilobal cross-section (3-14 leaf-shaped cross section), a hollow cross-section, Various cross-sectional shapes such as a letter-shaped section, a T-shaped section, an H-shaped section, an I-shaped (dogbone-shaped) section, and an array-shaped section may be used. Among these, a round cross section, an elliptical cross section and the like are widely used. Furthermore, the cross-sectional shape may be hollow from the viewpoint of reducing the specific gravity of the fiber.

  Although the fiber length of each fiber is not particularly limited, it may be a short fiber. In the case of a dry nonwoven fabric by the card method, 20 to 70 mm is preferable, and particularly 25 to 60 mm is uniform from the viewpoint of card passing property. It is preferable in that a formation web is easily obtained, and can be appropriately adjusted according to the application.

  The fiber diameter of each fiber should just be about 5 micrometers or more from points, such as a mechanical characteristic, for example, 9-32 micrometers, Preferably it is 10-25 micrometers, More preferably, it is about 10-20 micrometers.

The basis weight of the nonwoven fabric of the surface layer is, for example, about 10 to 60 g / m ² , preferably 20 to 50 g / m ² , and more preferably about 25 to 45 g / m ² (particularly 30 to 40 g / m ² ).

The apparent density of the surface layer (apparent density before lamination) is, for example, 0.03 to 0.20 g / cm ³ , preferably 0.04 to 0.18 g / cm ³ , and more preferably 0.05 to 0.15 g / cm. It is about cm < ³ > (especially 0.06-0.12 g / cm < ³ >).

  The surface layer porosity (porosity before lamination) may be, for example, 80% or more, for example, 80 to 99%, more preferably 82 to 98%, more preferably about 85 to 95%. Also good.

  The thickness of the surface layer (thickness before lamination) is, for example, 0.3 to 0.8 mm, preferably 0.35 to 0.7 mm, more preferably 0.4 to 0.65 mm (particularly 0.45 to 0.6 mm). )

(Surface layer manufacturing method)
When using a plurality of types of fibers, the nonwoven fabric or non-woven fiber aggregate constituting the surface layer is a conventional method, for example, a spunlace method, a needle punch method, a thermal bond, after blending fibers obtained by various methods. Can be manufactured in an integrated manner by a method such as a steam jet method. Among these methods, if importance is attached to economy, a spunlace method that can be industrially produced at high speed may be used. In addition, when the liquid retention performance is increased by increasing the bulk, the thermal bond method or the steam jet method (particularly, it is possible to achieve uniform adhesion in the thickness direction, and to achieve both high form retention and bulkiness. , Steam jet method) or the like.

  In the case of the spunlace method, a plurality of fibers may be mixed and opened by carding with a card machine, for example, to create a nonwoven web. This non-woven web includes a parallel web arranged in the traveling direction of the card machine according to a blending ratio of fibers constituting the web, a cross web in which parallel webs are cross-laid, a random web arranged randomly, or a parallel web and a random web. Any of the semi-random webs arranged in the middle of the above may be used, but since the entanglement of fibers occurs in the transverse direction and the elongation in the transverse direction is hindered, the random webs tend to be less flexible. A parallel web and a semi-random web that can ensure the softness and extensibility in the transverse direction of the nonwoven fabric are preferable to the cross web.

Further, in the spunlace method, the obtained nonwoven web is subjected to a hydroentanglement process. In the water entanglement process, for example, a water flow that is jetted in a column shape at high pressure from a nozzle plate in which jet holes having a diameter of 0.05 to 0.20 mm and intervals of about 0.30 to 1.50 mm are arranged in one or two rows is perforated. The non-woven web placed on the elastic support member is caused to collide, and the fibers constituting the non-woven web are three-dimensionally entangled and integrated. When three-dimensional entanglement is applied to the nonwoven web, the nonwoven web is placed on the moving porous support member. For example, the water pressure is 10 to 150 kg / cm ² (≈1 to 15 MPa), preferably 20 to 120 kg / cm. ² (≈2 to 12 MPa), more preferably 30 to 100 kg / cm ² (≈3 to 10 MPa). The injection holes are arranged in a row in a direction perpendicular to the traveling direction of the nonwoven web, and the nozzle plate on which the injection holes are arranged is perpendicular to the traveling direction of the nonwoven web placed on the porous support member. It is preferable that the water flow is caused to collide uniformly with the nonwoven fabric web by causing the water flow to swing at the same interval as the spray hole interval. The porous support member on which the nonwoven fabric web is placed is not particularly limited as long as the water flow can penetrate the nonwoven fabric web, such as a mesh screen such as a wire mesh or a perforated plate. Although the distance of a jet hole and a nonwoven fabric web can be selected according to water pressure, it is about 1-10 cm, for example. If it is outside this range, the texture of the nonwoven fabric tends to be disturbed or the three-dimensional entanglement is insufficient.

  After the water entanglement process, a drying process may be performed. As the drying treatment, it is preferable to remove excess moisture from the nonwoven web after treatment, and a known method can be used to remove excess moisture. For example, excessive moisture may be removed to some extent using a squeezing device such as a mangle roll, and then the remaining moisture may be removed using a drying device such as a suction band type hot air circulation dryer.

  In the case of the steam jet method, fibers may be entangled by spraying high-temperature steam (high-pressure steam) onto the obtained nonwoven web to form an adhesion layer. In the steam jet method, in addition to entanglement between fibers, fibers are bonded by using a web containing hydrophilic fibers (wet heat adhesive fibers) having at least a wet heat adhesive resin such as an ethylene-vinyl alcohol copolymer on the surface. Wet heat adhesion may be used. That is, in the steam jet method, when passing the fiber web transported by the belt conveyor through the high-speed high-temperature steam flow ejected from the nozzle of the steam spraying device, the fibers can be entangled with the sprayed high-temperature steam. When the wet heat adhesive fibers are included, the wet heat adhesive fibers are fused, and the fibers (wet heat adhesive fibers, or the wet heat adhesive fibers and the hydrophobic fibers) are uniformly three-dimensionally bonded in the thickness direction.

  In order to supply water vapor to the fiber web, a conventional water vapor jet apparatus is used. In order to inject high-temperature water vapor from both sides of the fiber web, the water vapor injection device may be a combination of two belt conveyors so as to sandwich the fiber web, and each of the belt conveyors may be equipped with a water vapor injection device. As the endless belt used for the conveyor, a net that is roughly coarser than 90 mesh (for example, a net of about 10 to 60 mesh) is usually used.

  A nozzle for injecting high-temperature steam uses a plate or a die in which predetermined orifices are continuously arranged in one or more rows in the width direction, and the orifices are arranged in the width direction of the fiber web to be supplied. What is necessary is just to arrange. The diameter of the orifice is, for example, about 0.05 to 2 mm (particularly 0.1 to 1 mm), and the pitch of the orifice is, for example, about 0.5 to 3 mm (particularly, 1 to 2 mm).

  The pressure of the high temperature steam is, for example, about 0.1 to 2 MPa, preferably about 0.2 to 1.5 MPa, and more preferably about 0.3 to 1 MPa. The temperature of the high-temperature steam is, for example, about 70 to 150 ° C, preferably about 80 to 120 ° C, and more preferably about 90 to 110 ° C. The processing speed of the high temperature steam is, for example, 200 m / min or less, preferably 0.1 to 100 m / min, and more preferably about 1 to 50 m / min.

(Back layer)
The back layer has a role as a buoyancy layer (water floating layer) for floating the laminated nonwoven fabric in water. The back layer is formed of a nonwoven fabric containing non-hydrophilic fibers from the viewpoint that water can be prevented from penetrating into the nonwoven fabric fiber structure and air can be retained inside the fiber structure.

  As the non-hydrophilic fiber, the non-hydrophilic fiber exemplified in the surface layer can be used. These non-hydrophilic fibers can be used alone or in combination of two or more. Of these non-hydrophilic fibers, polyolefin fibers, polyester fibers, and polyamide fibers are generally used.

As the polyolefin fiber, for example, poly C _2-4 olefin fiber is widely used, and examples thereof include polyethylene fiber, polypropylene fiber, ethylene-propylene copolymer fiber, and polybutene fiber.

Polyester C _2-4 alkylene arylate fibers are commonly used as the polyester fibers, and examples thereof include polyethylene terephthalate (PET) fibers, polytrimethylene terephthalate fibers, polybutylene terephthalate (PBT) fibers, and polyethylene naphthalate fibers. Of these, PET fibers and PBT fibers (particularly PBT fibers) are preferred.

  As the polyamide fiber, aliphatic polyamide is widely used, and examples thereof include polyamide 6 fiber, polyamide 66 fiber, polyamide 610 fiber, polyamide 10 fiber, polyamide 12 fiber, and polyamide 6-12 fiber. Of these, polyamide 6 fibers and polyamide 66 fibers are preferred.

Among these non-hydrophilic fibers, polyolefin fibers and polyester fibers are preferable because they are easy to float in water, and polyolefin fibers are particularly preferable because they are highly hydrophobic and have a low true density. The polyolefin fiber is preferably a polyethylene fiber, a polypropylene fiber, or an ethylene-propylene copolymer fiber, and a composite fiber exemplified in the surface layer (a core portion made of a polypropylene resin and a sheath portion made of a polyethylene resin) Core-sheath type composite fibers, etc.), but polypropylene is superior in that it has excellent heat resistance, the adhesive layer is formed of a hot-melt adhesive resin, and the fiber structure is easily retained even when laminated by heat treatment. System fibers are preferred. Polypropylene fibers are usually composed of a polypropylene resin mainly composed of isotactic polypropylene, and other copolymerizable monomers (for example, ethylene, butene, pentene) as long as the properties of polypropylene are not impaired. , Α-C _2-12 olefin monomers such as methylpentene, hexene and octene, and acrylic monomers such as (meth) acrylic acid and alkyl (meth) acrylate). The ratio of the other copolymerizable monomer is, for example, 10 mol% or less, preferably 5 mol% or less. In the present invention, it is preferable to use a polyolefin fiber having a true density smaller than that of water because it easily floats in water. However, when the specific density of the laminated nonwoven fabric is larger than that of water by using a specific laminated nonwoven structure, Even so, a wiper floating in water can be prepared. Therefore, since the ratio of the wiping layer can be increased, a wiper that floats on water can be prepared while maintaining high wiping properties.

  The melting point of the polypropylene resin may be, for example, about 120 to 200 ° C, preferably about 130 to 180 ° C, more preferably about 150 to 170 ° C (particularly 160 to 170 ° C).

  The back layer may contain hydrophilic fibers as long as the properties of the non-hydrophilic fibers are not impaired. Examples of the hydrophilic fiber include hydrophilic fibers exemplified in the surface layer. The ratio of the hydrophilic fiber may be, for example, 10% by mass or less, preferably 5% by mass or less with respect to the entire back layer.

  The fibers constituting the nonwoven fabric of the back layer may also contain the same conventional additives as the surface layer. The ratio of the additive is the same as the ratio of the surface layer. In order to improve hydrophobicity, a water repellent may be included, but the addition of the water repellent has a problem of volatilization as a harmful component. In the present invention, in particular, by using a polyolefin fiber having high hydrophobicity, high hydrophobicity can be expressed without substantially containing a water repellent.

  The cross-sectional shape of the fiber is not particularly limited and can be selected from the same shape as the surface layer, and a round cross-section, a flat cross-section, an elliptic cross-section, etc. are generally used. Furthermore, the cross-sectional shape may be hollow from the viewpoint of reducing the specific gravity of the fiber.

  The fiber diameter of the fibers is, for example, about 1 to 100 μm, preferably 5 to 50 μm, more preferably 8 to 30 μm (particularly 10 to 20 μm) in order to form fine voids.

The basis weight of the nonwoven fabric of the back layer is, for example, about 10 to 50 g / m ² , preferably about 12 to 45 g / m ² , and more preferably about 15 to 40 g / m ² (particularly 20 to 35 g / m ² ).

The apparent density of the back layer (apparent density before lamination) is, for example, 0.03 to 0.20 g / cm ³ , preferably 0.04 to 0.18 g / cm ³ , and more preferably 0.05 to 0.15 g. / Cm ³ (particularly 0.06 to 0.12 g / cm ³ ).

  The porosity of the back layer (porosity before lamination) may be, for example, 80% or more, for example, 80 to 99%, more preferably 82 to 98%, and more preferably about 85 to 95%. May be.

  The thickness of the back layer (thickness before lamination) is, for example, about 0.1 to 0.7 mm, preferably about 0.2 to 0.6 mm, and more preferably about 0.3 to 0.5 mm.

(Back layer manufacturing method)
The nonwoven fabric or non-woven fiber aggregate constituting the back layer can be produced by a conventional method, for example, a spunbond method, a melt blown method, or the like. Of these methods, the spunbond method is preferred because a bulky nonwoven fabric can be easily produced. Furthermore, in the spunbond method, since the oil agent derived from the spinning process is not mixed, the effect of water repellency (hydrophobicity) due to the polymer itself of hydrophobic fibers such as polyolefin fibers is efficiently expressed.

  The spunbond nonwoven fabric may be a commercially available spunbond nonwoven fabric or may be produced by a conventional method. As a conventional spunbond method, first, a resin constituting the back layer is melted and kneaded by an extruder, a flow of the molten polymer is guided to a spinning head, a flow rate is measured, and the resin is discharged from a spinning nozzle hole. Next, after the discharged yarn is cooled by a cooling device, it is pulled and thinned by a high-speed air current so as to obtain a desired fineness using a suction device such as an air jet nozzle. Thereafter, the nonwoven web is formed by depositing on a movable collection surface while opening the fiber. Finally, a spunbond nonwoven fabric can be obtained by partially thermocompressing and winding the web.

(Adhesive layer)
The adhesive layer has a role of bonding the surface layer and the back layer. In the present invention, by providing an adhesive layer, it is not necessary to perform strong embossing with respect to the adhesion between the surface layer and the back layer, and the surface layer and the back surface are not impaired without damaging the wiping property of the surface layer or the water floatability of the back layer. Adhesive force required as a wiper can be imparted between the layers.

  The adhesive layer may be composed of an adhesive resin as long as the surface layer and the back layer can be adhered to each other. However, the adhesive layer is preferably composed of a hot-melt adhesive resin from the viewpoint that it can be firmly adhered even during the wiping operation. The melting point or softening point of the hot-melt adhesive resin can be selected according to the type of resin constituting the surface layer and the back layer. For example, it is less than 120 ° C., for example, 60 to 119 ° C., preferably 80 to 118 ° C. Preferably it is about 90-115 degreeC (especially 100-110 degreeC).

  As the hot melt adhesive resin, a resin having a lower melting point or softening point than the fibers constituting the surface layer and the back layer, for example, polyolefin resin, acrylic resin, polyamide resin, polyurethane resin, olefin elastomer, styrene resin Examples thereof include elastomers, polyester elastomers, polyamide elastomers, and thermoplastic polyurethane elastomers. These hot melt adhesive resins can be used alone or in combination of two or more.

  Of these hot melt adhesive resins, polyolefin resins and olefin elastomers are preferred because they are excellent in adhesion to the surface layer and the back layer and have a low true density.

As the polyolefin-based resin, a polyethylene-based resin is preferable, and an ethylene-based copolymer having ethylene and another copolymerizable monomer as a polymerization component is particularly preferable. Other copolymerizable monomers include, for example, α-C _3-12 olefin monomers such as propylene, butene, pentene, methylpentene, hexene, octene, vinyl acetate, (meth) acrylic acid, (meta ) Other vinyl monomers such as acrylic acid alkyl ester and maleic anhydride. These copolymerizable monomers can be used alone or in combination of two or more. The ratio of ethylene units to other copolymerizable monomer units is ethylene / other copolymerizable monomers = 99/1 to 1/99, preferably 95/5 to 5/95, more preferably 90. / 10 to 10/90 or so. Of these copolymerizable monomers, α-C _4-10 olefin monomers such as butene and octene, vinyl acetate, (meth) acrylic acid and the like are preferable.

  Examples of the olefin elastomer include ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM), styrene-ethylene-propylene block copolymer (SEP), styrene-ethylene-propylene-styrene block copolymer ( SEPS) and styrene-ethylene-butylene-styrene block copolymer (SEBS). These olefin elastomers can be used alone or in combination of two or more. As SEP, SEPS, and SEBS, commercially available products such as “Septon” manufactured by Kuraray Co., Ltd. can be used.

Among polyolefin-based resins and olefin-based elastomers, ethylene-α-C _6-10 olefin (octene, etc.) copolymer from the viewpoint of excellent balance between adhesion to the surface layer and back layer and water floatability of the laminated nonwoven fabric Is particularly preferred. As an ethylene-α-C _6-10 olefin (such as octene) copolymer, commercially available “engage” manufactured by Dow Chemical Co., Ltd. can be used.

  The adhesive form of the adhesive layer is not particularly limited, and examples thereof include a form in which a hot-melt adhesive resin is interposed in a layered form and a form in which a fibrous hot-melt adhesive resin is interposed.

  When intervening in a layer form, the hot melt adhesive resin is not limited to an aspect interposing in the form of a layer over the entire surface layer or back layer, but may be an aspect interposing on a part of the surface of the surface layer or the back layer. When intervening on a part of the surface, the adhesive layer may be formed regularly or randomly in the form of dots (spots) on the surface of the surface layer or the back layer, or may be formed in a linear or lattice shape.

  In the case where a fibrous hot melt adhesive resin is present, the hot melt adhesive fiber may be in a form intervening on a part of the surface or the back layer, but in the form of a woven or non-woven fabric, The aspect which intervenes in the whole surface of a back layer may be sufficient. Furthermore, when intervening in the form of woven fabric or non-woven fabric, at least a part of the fiber shape may be lost and formed into a film by heat treatment for adhesion.

  Among these, it is composed of adhesive fibers (binder fibers) composed of the hot melt adhesive resin from the viewpoint that it can easily form an adhesive layer and can be uniformly adhered without impairing the flexibility as a wiper. In particular, an adhesive layer formed of a non-woven fabric composed of the adhesive fibers (polyethylene fibers having a lower melting point than the fibers constituting the surface layer and the back layer) is preferable.

  When the adhesive layer is composed of a nonwoven fabric, the adhesive layer may contain non-adhesive fibers as long as the properties of the adhesive fibers are not impaired. The ratio of the non-adhesive fiber may be, for example, 10% by mass or less, preferably 5% by mass or less with respect to the entire adhesive layer.

  The adhesive layer may also contain conventional additives similar to the surface layer. The ratio of the additive is the same as the ratio of the surface layer.

  When the adhesive layer is composed of binder fibers, the cross-sectional shape of the fiber is not particularly limited, and can be selected from the same shape as the surface layer, and a round cross-section, a flat cross-section, an elliptic cross-section, etc. are generally used.

  The fiber diameter of a fiber is 1-40 micrometers, for example, Preferably it is 2-35 micrometers, More preferably, it is about 3-30 micrometers.

When the adhesive layer is composed of a nonwoven fabric, the basis weight is, for example, 5 to 30 g / m ² , preferably 6 to 25 g / m ² , more preferably 7 to 20 g / m ² (particularly 8 to 15 g / m ² ). Degree.

The apparent density of the adhesive layer (apparent density before lamination) is, for example, 0.03 to 0.2 g / cm ³ , preferably 0.05 to 0.15 g / cm ³ , and more preferably 0.06 to 0.10 g. / Cm ³ or so.

  The porosity of the adhesive layer (the porosity before lamination) may be, for example, 80 to 99%, preferably 82 to 98%, and more preferably 85 to 95%.

  The thickness of the adhesive layer (thickness before lamination) is, for example, 0.05 to 0.5 mm, preferably 0.08 to 0.3 mm, and more preferably about 0.1 to 0.2 mm.

(Adhesive layer production method)
Although an adhesive layer can be manufactured according to the form, when a contact bonding layer is a nonwoven fabric, since a fabric weight is easy to make small, a melt blown method is preferable.

  In the melt blown method, usually, a method of blowing high-temperature air from a slit formed in the vicinity of the spinneret is used in order to blow the spun fiber toward the net. The temperature of the air can be selected from a range of spinning temperature ± 50 ° C. (particularly ± 30 ° C.), and is usually the same temperature as the spinning temperature.

  The spinning temperature can be selected according to the type of resin, and is, for example, about 150 to 350 ° C. (especially 250 to 320 ° C.). The nozzle hole diameter of the spinneret is, for example, about 0.1 to 1 mm (particularly 0.2 to 0.5 mm), and the single hole discharge amount is, for example, 0.01 to 0.5 g / minute (particularly 0.1 to 0.1 mm). About 0.3 g / min).

The flow rate of air to be sprayed per 1 m of nozzle length (air flow rate) is, for example, 2 to 30 N · m ³ / m, preferably ^{3 to} 25 N · m ³ / m, more preferably 4 to 20 N · m ³ / m (particularly 5 to 15 N · m ³ / m). Hot air temperature is about 160-350 degreeC (especially 260-320 degreeC), for example.

  The distance (collection distance) between the nozzle opening and the collection net is, for example, 10 to 50 cm (particularly about 15 to 30 cm. If the collection distance is too small, the amount of fluff scattering increases and the web is formed. However, if the collection distance is too large, the web formation tends to be rough.

[Laminated nonwoven fabric]
The method for producing the laminated nonwoven fabric of the present invention is not particularly limited as long as the surface layer and the back layer can be integrated through the adhesive layer. However, when a hot melt adhesive resin is used as the adhesive layer, a conventional thermocompression bonding is performed. The method of integrating by the utilized method may be sufficient. As a thermocompression bonding method, a pressure bonding method (calendering) using a heating roll can be used. For example, a method using a rubber roll / steel roll or a method using an embossing roll / steel roll can be used. The heating temperature at the time of press-bonding may be a temperature at which the hot-melt adhesive resin melts and the fibers constituting the surface layer and the back layer do not melt, for example, 100 to 140 ° C, preferably 105 to 130 ° C, more preferably Is about 110-130 ° C. Of these methods, embossing using an embossing roll or the like is preferable because both flexibility and adhesiveness can be achieved. The crimping area in the embossing is, for example, about 5 to 50%, preferably 10 to 40%, more preferably 15 to 30% (particularly 15 to 25%) with respect to the area of the nonwoven fabric surface.

  The laminated nonwoven fabric of the present invention thus obtained has high water absorption because the surface layer contains hydrophilic fibers, and has a water absorption rate of 200% or more, for example, 200 to 1000%, preferably 250 to 800%. More preferably, it is about 300 to 500%. Furthermore, the water absorption rate is also high, and the surface water absorption rate of the surface layer based on the dropping method of JIS L1907-7.1.1 is 10 seconds or less, for example, 0.1 to 10 seconds, preferably 0.5 to 8 seconds. More preferably, it is about 1 to 5 seconds.

  On the other hand, the laminated nonwoven fabric of the present invention combines a back layer containing non-hydrophilic fibers via an adhesive layer with a surface layer containing hydrophilic fibers despite having such excellent water absorption. Because it floats on the water. For example, 100 liters of water is filled in a φ500 mm cylindrical tank, a 20 cm × 20 cm square laminated non-woven fabric is placed on the surface of the water, and after stirring for 2 minutes at 90 rpm with a φ25 mm pipe, 10 minutes have passed. Even floating on the surface.

The basis weight of the laminated nonwoven fabric of the present invention is, for example, about 50 to 120 g / m ² , preferably 60 to 100 g / m ² , more preferably 62 to 90 g / m ² (particularly 65 to 80 g / m ² ).

Apparent density of the laminated nonwoven fabric, for example, may be less than 1 g / cm ^3, for example, 0.05~0.9g / cm ^3, preferably may be about 0.08~0.5g / cm ³ From the point that both high wiping properties and water floatability can be achieved, it may be more preferably about 0.1 to 0.3 g / cm ³ (particularly 0.1 to 0.2 g / cm ³ ). The apparent density of the laminated nonwoven fabric can be selected according to the type of non-hydrophilic fibers constituting the back layer. For example, when the back layer is composed of polyolefin fibers (particularly polypropylene fibers), 0.5 g / cm ³ or less (for example, 0.1 to 0.5 g / cm ³ ), for example, 0.1 to 0.3 g / cm ³ , preferably 0.1 to 0.2 g / cm ³ , and more preferably May be about 0.12 to 0.2 g / cm ³ (particularly 0.12 to 0.15 g / cm ³ ). Also, if the backing layer is composed of polyester fibers (especially PBT fiber), 0.1 to 0.4 g / cm ³ may be a (especially 0.12~0.4g / cm ³⁾ approximately. Furthermore, when the back layer is composed of polyamide fibers (particularly polyamide 6 fibers), it may be about 0.1 to 0.13 g / cm ³ (particularly 0.1 to 0.12 g / cm ³ ).

True density of the laminated nonwoven fabric (true specific gravity), for example, 0.95~1.08g / cm ^{3 approximately, 0.96~1.07g / cm 3, 0.97~1.06g /} cm 3, 0.98 About 1.05 g / cm ³ . In the present invention, when the true density is larger than water (when exceeding 1 g / cm ³ ), for example, about 1.01 to 1.3 g / cm ³ (particularly 1.15 to 1.25 g / cm ³ ) Can also float in the water.

  The thickness of the laminated nonwoven fabric can be selected, for example, from a range of about 0.1 to 1 mm, for example, 0.2 to 0.8 mm, preferably about 0.3 to 0.7 mm. From the point which can make floatability compatible, More preferably, it is about 0.4-0.65 mm (especially 0.45-0.60 mm).

  In the laminated nonwoven fabric of the present invention, the ratio of the basis weight of the surface layer to the total basis weight of the back layer and the adhesive layer can be selected from the range of the former / the latter = 60/40 to 30/70, for example, 55/45 Although it is about 40/60, it is preferably 55/45 to 45/55, more preferably about 50/50 to 45/55 from the viewpoint that both high wiping properties and water floatability can be achieved.

  The ratio of the basis weight of the surface layer to the basis weight of the adhesive layer is, for example, the former / the latter = 90/10 to 50/50, preferably 85/15 to 60/40, and more preferably about 80/20 to 70/30. . When the basis weight of both layers is within this range, the adhesiveness between the layers is excellent, the flexibility of the laminated nonwoven fabric is also maintained, and the wiping property is excellent.

  In the entire laminated nonwoven fabric, the ratio (mass ratio) of hydrophilic fibers to non-hydrophilic fibers is the former / the latter = 20/80 to 50/50, preferably 25/75 to 55/45, more preferably 30/70. It is about -40/60 (especially 35 / 65-40 / 60). In this invention, while adjusting a fabric weight ratio to the said range and adjusting the ratio of a hydrophilic fiber and a non-hydrophilic fiber, it can be compatible with a wiping characteristic and water floating property.

When the adhesive layer is formed of a nonwoven fabric, the air permeability of the laminated nonwoven fabric by the Frazier method is 1 cm ³ / (cm ² · sec) or more, for example, 1 to 1000 cm ³ / (cm ^2). Second), preferably 10 to 500 cm ³ / (cm ² · second), more preferably 30 to 300 cm ³ / (cm ² · second) (particularly 50 to 200 cm ³ / (cm ² · second)). Also good.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, measurement methods or evaluation methods for each physical property, and raw materials used in the examples are shown below. Unless otherwise specified, “%” represents “mass%”.

(1) Weight per unit (g / m ² )
Measured according to JIS L1913 “Testing method for general short fiber nonwoven fabric”.

(2) Thickness (mm), apparent density (g / cm ³ )
The thickness was measured according to JIS L1913 “Test method for general short fiber nonwoven fabric”, and the apparent density was calculated from this value and the basis weight value.

(3) Average fiber diameter of nonwoven fabric The nonwoven fabric was enlarged and photographed with a scanning microscope, the diameter of 100 arbitrary fibers was measured, and the average value was calculated.

(4) Air permeability Measured by the fragile method according to JIS L1096.

(5) Water absorption rate After the nonwoven fabric was immersed in ion exchange water for 30 seconds, the weight of the nonwoven fabric before and after water absorption was measured, and the water absorption rate of ion exchange water was calculated from the following formula.

    Water absorption rate (%) = (weight after water absorption−weight before water absorption) / weight before water absorption × 100.

(6) Surface water absorption rate It measured according to the dropping method of JIS L1907-7.1.1.

(7) Water floatability After filling a cylindrical tank of φ500 mm with 100 liters of water, placing a 20 cm × 20 cm square laminated nonwoven fabric on the water surface, and stirring for 2 minutes at 90 rpm with a φ25 mm pipe The fabric was allowed to stand for 10 minutes and the non-woven fabric was measured according to the following criteria.

○: Floating on the surface of water △: Floating on the surface of the water, but partially submerged in water ×: Submerged in the bottom of the water.

(8) Interlayer adhesion A wiper operation was performed as a wiper, and the peeling state between layers due to a load during wiping was evaluated according to the following criteria.

○: not peeled Δ: partly peeled ×: peeled

[Raw material of laminated nonwoven fabric]
(Surface)
Viscose rayon fiber (rayon): “Hope” manufactured by Ohmi Kenshi Co., Ltd., average fiber diameter 12 μm (1.7 dtex), fiber length 40 mm
PET fiber (hydrophilic PET): “Tetron 471” manufactured by Toray Co., Ltd., average fiber diameter 12 μm (1.7 dtex), fiber length 51 mm
PP / PE core-sheath composite fiber (PP / PE): “HR-NTW” manufactured by Ube Nitto Kasei Co., Ltd., average fiber diameter 1.7 dtex, fiber length 51 mm
(Back layer)
Polypropylene (PP) spunbonded non-woven fabric A: “ELTAS Limp PC8030” manufactured by Asahi Kasei Fibers Co., Ltd., basis weight 30 g / m ² , thickness 0.4 mm, melting point 163 ° C.
Polypropylene (PP) spunbond non-woven fabric B: “ELTASLINP 8020” manufactured by Asahi Kasei Fibers, 20 g / m ² , weight of 0.3 mm, melting point 163 ° C.
Polyamide (PA) spunbonded non-woven fabric: “N01020” manufactured by Asahi Kasei Fibers Co., Ltd., basis weight 20 g / m ² , thickness 0.13 mm, melting point 205 ° C.
PET spunbond nonwoven fabric: “3301A” manufactured by Toyobo Co., Ltd., basis weight 30 g / m ² , thickness 0.2 mm, melting point 253 ° C.
PBT spunbond nonwoven fabric: 30 g / m ² per unit area
(PP / PE) thermal bond nonwoven fabric of PP / PE core-sheath composite fiber: “9513F-S” manufactured by Shinwa Co., Ltd., basis weight 13 g / m ² , thickness 0.1 mm, melting point 165 ° C. (core) / 130 ° C. ( Sheath).

(Adhesive layer)
Polyethylene resin (engage): Dow Chemical's “engage 8402”, melting point 105 ° C.

Example 1
(1) Preparation of surface layer After uniformly blending 45 parts by mass of rayon fiber, 30 parts by mass of PET fiber and 25 parts by mass of PP / PE core-sheath composite fiber, a semi-random card web having a basis weight of 35 g / m ² is produced by a conventional method. The card web is placed on a punching drum support having an aperture ratio of 25% and a hole diameter of 0.3 mm and continuously transferred in the longitudinal direction at a speed of 50 m / min. The entanglement process was performed and the entangled fiber web was manufactured. In this entanglement process, two nozzles provided with orifices having a hole diameter of 0.10 mm at intervals of 0.6 mm along the width direction of the web are used (distance 20 cm between adjacent nozzles). The water pressure of the high-pressure water stream injected from No. 2 was set to 3.0 MPa, and the water pressure of the high-pressure water stream injected from the nozzles in the second row was set to 4.0 MPa. Further, it was dried at 120 ° C. to obtain a spunlace nonwoven fabric having a basis weight of 35 g / m ² and a thickness of 0.5 mm.

(2) Preparation of adhesive layer Using polyethylene resin (engage) as a raw material, it was melt extruded at a single hole discharge rate of 0.2 g / min to a spinning nozzle having a hole diameter of 0.3 mm and a hole number of 1500 holes / m. Hot air temperature (primary air temperature) 310 ° C, air quantity 10N · m ³ / m per 1m of nozzle length, the distance between the nozzle and the metal net of the forming collector is sprayed onto the metal mesh under the condition of 20cm, and collected by suction from the bottom. A melt blown nonwoven fabric having a basis weight of 10 g / m ² was obtained.

(3) Preparation of laminated nonwoven fabric A spunlace nonwoven fabric as a surface layer, a melt blown nonwoven fabric as an adhesive layer, and a PP spunbond nonwoven fabric A as a backing layer are laminated in this order, and an embossed pattern roll / steel roll with a crimping area of 18% is used. The laminated nonwoven fabric was obtained by thermocompression bonding. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 2
A laminated nonwoven fabric was obtained in the same manner as in Example 1 except that PP spunbond nonwoven fabric B was used instead of PP spunbond nonwoven fabric A as the back layer. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 3
In the preparation of the surface layer, a laminated nonwoven fabric was obtained in the same manner as in Example 1 except that 80 parts by mass of rayon fiber and 20 parts by mass of PP / PE core-sheath composite fiber were used. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 4
The laminated nonwoven fabric obtained in Example 3 was further pressed with a rubber / metal calender roll at 120 ° C., 60 kgf / cm, and 3 m / min. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 5
The laminated nonwoven fabric pressed in Example 4 was further pressed at 80 ° C., 400 kgf / cm, and 2 m / min with a metal / metal calender roll. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 6
A laminated nonwoven fabric was obtained in the same manner as in Example 2 except that a PA spunbond nonwoven fabric was used instead of the PP spunbond nonwoven fabric B as the back layer. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 7
A laminated nonwoven fabric was obtained in the same manner as in Example 1 except that a PET spunbond nonwoven fabric was used instead of the PP spunbond nonwoven fabric A as the back layer. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 8
A laminated nonwoven fabric was obtained in the same manner as in Example 1 except that a PBT spunbond nonwoven fabric was used instead of the PP spunbond nonwoven fabric A as the back layer. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Example 9
The laminated nonwoven fabric pressed in Example 8 was further pressed at 80 ° C., 400 kgf / cm, and 2 m / min with a metal / metal calender roll. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Comparative Example 1
A laminated nonwoven fabric was obtained in the same manner as in Example 1 except that a PP / PE thermal bond nonwoven fabric having a basis weight of 13 g / m ² was used instead of the PP spunbond nonwoven fabric A as the back layer. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Comparative Example 2
A laminated nonwoven fabric was obtained in the same manner as in Example 1 except that the adhesive layer was not used. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

Comparative Example 3
A laminated nonwoven fabric was obtained in the same manner as in Example 1 except that the back layer and the adhesive layer were not used. The structure of each layer of the obtained laminated nonwoven fabric is shown in Table 1, and the characteristics of the laminated nonwoven fabric are shown in Table 2.

  From the results of Table 2, the laminated nonwoven fabric of the present invention has high water absorption and excellent water floatability, whereas the laminated nonwoven fabrics of Comparative Examples 1 and 3 have low water floatability, and the laminated nonwoven fabric of Comparative Example 2 Has low interlayer adhesion.

  The laminated nonwoven fabric of the present invention is used for a water tank or a wiper used for cleaning a water tank in a factory facility or the like, and in particular, a nuclear power plant core and its peripheral devices (for example, around a spent fuel pool or a cavity). It is useful for wipers used in tanks and tanks filled with water.

Claims (18)

  A laminated nonwoven fabric composed of a surface layer formed of a nonwoven fabric containing hydrophilic fibers, a back layer formed of a nonwoven fabric containing non-hydrophilic fibers, and an adhesive layer interposed between the surface layer and the back layer And the ratio of the fabric weight of the said surface layer and the total fabric weight of the said back layer and the said contact bonding layer is the laminated nonwoven fabric whose former / latter = 55 / 45-40 / 60.   The laminated nonwoven fabric according to claim 1, wherein the nonwoven fabric of the surface layer contains 50% by mass or more of hydrophilic fibers.   The laminated nonwoven fabric according to claim 1 or 2, wherein the nonwoven fabric of the surface layer contains 10 to 50 parts by mass of non-hydrophilic fibers with respect to 100 parts by mass of hydrophilic fibers.   The laminated nonwoven fabric according to claim 3, wherein the hydrophilic fibers include cellulosic fibers, and the non-hydrophilic fibers include polyolefin fibers.   A core-sheathed polyolefin fiber comprising a core part composed of a cellulose-based fiber and a polyester fiber whose surface is hydrophilized and a non-hydrophilic fiber composed of a polypropylene-based resin and a sheath part composed of a polyethylene-based resin. The laminated nonwoven fabric according to claim 3.   The laminated nonwoven fabric according to any one of claims 1 to 5, wherein the surface nonwoven fabric is a hydroentangled nonwoven fabric.   The laminated nonwoven fabric according to any one of claims 1 to 6, wherein the nonwoven fabric of the back layer is composed of polyolefin fibers and / or polyester fibers. The laminated nonwoven fabric according to any one of claims 1 to 7, wherein the nonwoven fabric of the back layer is composed of polypropylene fibers, and the apparent density of the laminated nonwoven fabric is 0.5 g / cm ³ or less.   The laminated nonwoven fabric according to any one of claims 1 to 8, wherein the adhesive layer is formed of a nonwoven fabric composed of polyethylene fibers having a melting point lower than that of the fibers constituting the surface layer and the back layer.   The ratio of the fabric weight of the surface layer to the fabric weight of the adhesive layer is the former / the latter = 90/10 to 50/50. The laminated nonwoven fabric according to any one of claims 1 to 9.   The laminated nonwoven fabric according to any one of claims 1 to 10, wherein the laminated nonwoven fabric has a water absorption rate of 200% or more, and the surface layer has a surface water absorption rate of 10 seconds or less in accordance with the dropping method of JIS L1907-7.1.1. .   The laminated nonwoven fabric according to any one of claims 1 to 11, wherein in the entire laminated nonwoven fabric, the ratio (mass ratio) of hydrophilic fibers to non-hydrophilic fibers is the former / the latter = 20/80 to 50/50. Basis weight is 60 to 100 / ^{m 2,} a thickness of 0.40～0.65Mm, and according to any one of claims 1 to 12 an apparent density of 0.1 to 0.2 g / cm ³ Laminated nonwoven fabric.   The laminated nonwoven fabric according to any one of claims 1 to 13, wherein the true density is greater than water.   The laminated nonwoven fabric according to any one of claims 1 to 14, wherein each layer is thermally bonded by embossing.   A cylinder tank of φ500 mm was filled with 100 liters of water, a 20 cm × 20 cm square laminated non-woven fabric was placed on the surface of the water, and after stirring for 2 minutes at 90 rpm with a φ25 mm pipe, 10 minutes passed. The laminated nonwoven fabric according to any one of claims 1 to 15, which also floats on the water surface.   The wiper comprised with the laminated nonwoven fabric in any one of Claims 1-16.   The wiper according to claim 17, which is used for cleaning a tank or a tank filled with water.