JP2020007697A - Hydrophilic bulky nonwoven fabric - Google Patents

Abstract

To provide a hydrophilic bulky nonwoven fabric that is excellent in water permeability and suitable for a surface material of a sanitary material, such as a top sheet of a diaper.SOLUTION: The hydrophilic bulky nonwoven fabric is a hydrophilic bulky nonwoven fabric comprising a thermoplastic fiber and has a nonwoven fabric surface structure in which a ratio of sections where a maximum height in a unit section defined by an X direction and a Y direction is 30% or more with respect to a height at no-load in a Z direction (thickness) of the nonwoven fabric when a measurement reference length in a surface of the nonwoven fabric is set as 100 μm is 50% or more per 40000 of the number of sections corresponding to a 20 mm×20 mm of a surface area of the nonwoven fabric. The nonwoven fabric has a 25 mm or less of a water-permeable flow length value at 54 degrees inclination and has a 85% or more of a fourth-time water permeability durability index.SELECTED DRAWING: None

Description

  The present invention relates to a hydrophilic bulky nonwoven fabric, particularly when used as a surface material such as a sanitary material, in which urine and body fluids are absorbed without stagnation.

  In recent years, disposable diapers have become remarkably popular, and required quality and performance have been improved. The nonwoven fabric used as the top sheet of the diaper is required to have a performance (water permeability) that allows the body fluid to pass therethrough and the body fluid that has passed through the nonwoven fabric to be quickly transferred to the absorber. A material generally used as a material of a top sheet requiring water permeability is a hydrophobic polyolefin-based nonwoven fabric, and a surfactant is applied as a water-permeable agent to impart water permeability.

  Until now, in order to improve water permeability, for example, in Patent Literature 1 below, many techniques for improving a water-permeable agent have been adopted, and improvement in water permeability has been attempted. Improving water permeability means that it is necessary to select a surfactant with a higher activity, so when used as a surface material for sanitary materials, it tends to cause rash and eczema on the contacting skin surface, It is not preferable from the viewpoint of irritation to the skin.

  On the other hand, in Patent Document 2 below, a nonwoven fabric is subjected to a shaping process to make the surface of the nonwoven fabric an uneven structure, so that the contact area with the skin is reduced, and wetting return performance and durable water permeability, which are indicators of water permeability. Performance has been improved. However, in order to provide a concavo-convex structure, processing by special embossing or the like is required, so that the manufacturing cost is increased and the productivity is not high. In addition, a portion having a reduced thickness is generated by molding between the rolls, and the effect of improving the obtained water permeability is not dramatic.

  Further, in Patent Literature 3 below, unevenness is applied to a nonwoven fabric to improve the withdrawal of bodily fluids. However, there is a concern that this technique gives the skin a damp feel. When a flat nonwoven fabric is used as a topsheet for diapers and sanitary products, the entire nonwoven fabric comes into contact with a mixture of pulp, which is an absorber, and a polymer absorber located below the topsheet. When wearing a diaper or sanitary product, the weight of the user is applied to the topsheet and the absorbent body, and the nonwoven fabric, which is the topsheet, comes into more close contact with the absorbent body. However, when a nonwoven fabric having a concave and convex shape as in Patent Document 3 and having a hollow inside the convex portion is used as a topsheet, the convex portion of the nonwoven fabric and the absorber are not in contact with each other. Therefore, when bodily fluids adhere to the surface of the nonwoven fabric, it is difficult for the bodily fluids to quickly transfer to the absorber. Further, the bodily fluid attached to the protruding portion remains held inside the non-woven fabric due to surface tension, and may give a damp feel to the skin. Furthermore, when urinating, if the non-woven fabric has a flat shape, urine is treated on the entire surface of the non-woven fabric. That is, the amount of urine flowing into the concave portion becomes larger than the convex portion, and the water-permeable agent attached to the concave portion is washed away by the urine. If the water-permeable agent in the recess is washed away by the urine, the urine stays in the recess and may give a wet feeling to the wearer. Further, there is a concern that urine remaining in the concave portion evaporates with the passage of time, causing rash and eczema on the skin surface.

JP-A-10-53555 JP-A-2004-113489 International Publication No. 2012-086730

  In view of the above, an object of the present invention is to provide a hydrophilic bulky nonwoven fabric which is excellent in water permeability and suitable for a surface material of a sanitary material such as a diaper top sheet.

  As described above, the design of the surfactant to be provided as a water-permeable agent and the surface structure of the nonwoven fabric are important for achieving excellent water-permeability. In particular, by making the surface of the nonwoven fabric a rough structure with fine irregularities, when body fluids such as urine and sweat adhere to the surface of the nonwoven fabric, the rougher the surface structure, the lower the contact angle between the body fluid and the surface of the nonwoven fabric, Is easily drawn into the nonwoven fabric. The present inventors focused on the microstructure of the surface of the nonwoven fabric, studied the number of crimps of the fibers of the long-fiber nonwoven fabric, the bonding method, and the method of imparting water permeability, and as a result of repeated experiments, the nonwoven fabric with the fibers arranged in an appropriate range Has succeeded in improving the 45 ° inclined flow length value and the durable water permeability index, which are indicators of water permeability, and have completed the present invention.

That is, the present invention is as follows.
[1] A hydrophilic bulky nonwoven fabric composed of thermoplastic long fibers having a number of crimps of 5 to 45 pieces / 2.54 cm (inch), in the X direction when the measurement reference length on the surface of the nonwoven fabric is 100 μm The proportion of the section in which the maximum height in the unit section defined by the Y direction is 30% or more with respect to the height (thickness) of the nonwoven fabric in the Z direction at no load corresponds to the nonwoven fabric surface area of 20 mm × 20 mm. The nonwoven fabric has a surface structure of 50% or more per 40,000 sections, the nonwoven fabric has a 45 ° water permeation inclined flow length value of 25 mm or less, and has a fourth durability water permeability index of 85% or more. The hydrophilic bulky nonwoven fabric.
[2] The hydrophilic bulky nonwoven fabric according to the above [1], wherein the hydrophilic bulky nonwoven fabric has an orientation index in a thickness direction by X-ray CT of 0.43 or less.
[3] The hydrophilic bulky nonwoven fabric according to [1] or [2], wherein the hydrophilic bulky nonwoven fabric has a compression work amount of 0.20 gf · cm / cm ² or more and 1.00 gf · cm / cm ² or less.
[ 4 ] The hydrophilic bulky nonwoven fabric according to any of [1] to [ 3 ], wherein the thermoplastic fiber is a side-by-side type or an eccentric sheath-core type composite fiber.
[ 5 ] The hydrophilic bulky nonwoven fabric according to any one of [1] to [ 4 ], wherein the thermoplastic fiber is a polyolefin-based fiber.
[ 7 ] A sanitary material comprising the hydrophilic bulky nonwoven fabric according to any one of [1] to [ 5 ].

  Because the hydrophilic bulky nonwoven fabric of the present invention has excellent water permeability, sanitary materials, for example, sanitary napkins, incontinence pads, can be suitably used as a top sheet on the surface of disposable diapers, and further, for example, It can also be used for masks, warmers, tape bases, patch bases, first aid bases, packaging materials, wipe products, medical gowns, bandages, clothing, skin care sheets, and the like.

It is a drawing for explaining measurement of the maximum height (μm) in a unit section on the surface of a nonwoven fabric.

Hereinafter, embodiments of the present invention will be described in detail.
The nonwoven fabric of this embodiment is made of a thermoplastic fiber, and may be a long-fiber nonwoven fabric manufactured by a spunbond method or a short-fiber nonwoven fabric manufactured by a card method or the like. However, in the case of short-fiber nonwoven fabric, the fibers are aligned in the X direction or the Y direction during carding, and the surface is easily smoothed. From the viewpoint of strength, productivity, reduction of skin irritation, etc. As a constituent fiber, a long fiber manufactured by a spun bond method is preferable. In the present specification, a long fiber is a fiber having a fiber length of 55 mm or more. The shorter the fiber length, the more likely it is that the end portion of the fiber touches the skin. Therefore, the fiber length is preferably 55 mm or more because it gives a tactile feel.

  Examples of the thermoplastic resin constituting the thermoplastic fibers include, for example, polyethylene, polypropylene, polyolefin resins such as copolymerized polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyester resins such as copolyester, and nylon-6. And polyamide-based resins such as nylon-66 and copolymerized nylon, and biodegradable resins such as polylactic acid, polybutylene succinate and polyethylene succinate, and are not particularly limited. Polyolefin-based resins are preferred from the viewpoints of general use and the convenience of recovery since many uses are disposable materials from the viewpoint of the feeling of the nonwoven fabric and many uses.

  The form of the thermoplastic fiber is preferably crimped from the viewpoint of imparting characteristics to the surface structure of the nonwoven fabric. The number of crimps is preferably 5 pieces / 2.54 cm (inch) or more, more preferably 5 pieces / inch to 45 pieces / inch, still more preferably 10 pieces / inch to 40 pieces / inch, and particularly preferably 10 pieces / inch to 40 pieces / inch. Pcs / inch to 25 pcs / inch. In a nonwoven fabric composed of fibers having a number of crimps exceeding 45 pieces / inch, shrinkage and spots due to fiber crimping are conspicuous, the appearance of the nonwoven fabric is deteriorated, and the wetting return index is deteriorated due to spots. In addition, a nonwoven fabric composed of fibers having a number of crimps of less than 5 pieces / inch cannot obtain a desired surface roughness, and has a reduced thickness, impairs a texture, or hardly obtains a desired water permeability. Become.

  As means for imparting crimp to the fiber, crimp can be imparted by making the fiber cross section into an irregular cross-sectional shape and performing partial cooling during spinning cooling. Further, it is possible to exhibit crimp even in a conjugate fiber composed of two or more kinds of thermoplastic resins, and the constitution is changed to a side-by-side type (S / S), an eccentric sheath-core type (eccentric S / C), or the like. By doing so, crimps can be more easily developed. In the case of the eccentric sheath-core type (unbalanced S / C), the core may be exposed on the fiber surface, and the ratio of the core to the fiber surface is preferably 0 to 50%, more preferably 0 to 30%. %. When the ratio of the core portion of the fiber surface to the core portion is higher than 50%, the adhesion at the time of bonding as a nonwoven fabric is affected, and the fabric strength is easily reduced and fluff is likely to occur.

In the case of the eccentric sheath-core type (unbalanced S / C), the center of gravity of the cross-sectional area of the core is preferably shifted by 5 to 40% with respect to the center of gravity of the cross-sectional area of the composite fiber in order to obtain a desired number of crimps. . The displacement of the core is calculated by the following equation.
Core deviation (%) = (the shortest distance between the center of gravity of the cross-sectional area of the composite fiber and the center of gravity of the cross-sectional area of the core) / (diameter of yarn) × 100

When the fiber is a combination of two or more thermoplastic resins, any combination of the thermoplastic resins is possible as long as a desired effect is obtained.From the viewpoint of bonding fibers, A combination of thermoplastic resins having different melting points is preferred. The weight ratio of the resin having the higher melting point difference in the fiber is preferably 20 wt% or more and 80 wt% or less, more preferably 30 wt% or more and 80 wt% or less, and still more preferably 50 wt% or more and 70 wt% or less.
Further, from the viewpoint of the texture of the obtained nonwoven fabric, it is preferable to use a combination of polyolefin resins or a combination of a polyolefin resin and a polyester resin. When a polyolefin resin is used in combination, a composite fiber obtained by combining a resin such as polyethylene, polypropylene, or a copolymer of such a monomer with another α-olefin is used. The other α-olefin has 3 to 10 carbon atoms, and specifically includes propylene, 1-butene, 1-pentene, 1-hexane, 4-methyl-1-pentene, 1-octene and the like. Can be

When a polyolefin-based resin and a polyester-based resin are combined, the polyester-based resin preferably uses a single component of polyethylene terephthalate or a copolymer containing isophthalic acid or the like. Further, the polyethylene terephthalate may be modified by blending or the like, or may be added with an additive or the like.
Among them, as a combination of thermoplastic resins, the strength is strong, it is difficult to break when used, and it is excellent in processing suitability in the production of sanitary materials, and since the texture is good, the first component is polypropylene, the second component is The component is preferably polyethylene, and when the conjugate fiber is an eccentric sheath-core type, the core is preferably the first component and the sheath is preferably the second component.

  When the fiber is formed of the two thermoplastic resins, the first component polypropylene may be a polymer synthesized by a general Ziegler-Natta catalyst or a polymer synthesized by a single-site active catalyst represented by metallocene. Good. Further, ethylene random copolymerized polypropylene may be used. These may be used alone or in combination of two or more. In particular, it is preferable to use a homopolypropylene as a main component in terms of texture, strength, and dimensional stability.

  Further, from the viewpoint of spinnability in the production of fibers and the strength of the obtained fibers, the lower limit of the MFR of the polypropylene is preferably 20 g / 10 min or more, more preferably 30 g / 10 min or more, and still more preferably 40 g / 10 min or more. Most preferably, it is more than 53 g / 10 minutes. The upper limit of the MFR is preferably 85 g / 10 minutes or less, more preferably 70 g / 10 minutes or less, and still more preferably 60 g / 10 minutes or less. The MFR was measured in accordance with JIS-K7210 "Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic", Table 1, test temperature 230 ° C, test load 2.16 kg. .

When the fibers are formed of the two thermoplastic resins, the polyethylene of the second component may be a polymer synthesized by a general Ziegler-Natta catalyst or a polymer synthesized by a single-site active catalyst represented by metallocene. There may be. Polyethylene, high density polyethylene, preferably a linear low density polyethylene, it is preferred that the density is 0.92~0.97g / cm ^3, more preferably 0.925~0.96g / cm ³ It is.

In addition, from the viewpoint of spinnability in the production of fibers, the lower limit of the MI of polyethylene is preferably 10 g / 10 min or more, more preferably 15 g / 10 min or more. The upper limit of MI is preferably 100 g / 10 minutes or less, more preferably 60 g / 10 minutes or less, and further preferably 40 g / 10 minutes or less. MI was measured according to JIS-K7210 "Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of plastic-thermoplastic", Table 1, test temperature 190 ° C, test load 2.16 kg. .
When a polyester resin is used, the lower limit of the solution viscosity ηsp / c is preferably 0.2 or more, more preferably 0.6 or more. The upper limit of the solution viscosity ηsp / c is preferably 0.9 or less, more preferably 0.8 or less.

  The fibers constituting the nonwoven fabric of the present embodiment are preferably in the form of a long fiber web using a spun bond method from the viewpoint of strength and productivity. In the case of a composite long fiber combined with two or more kinds of thermoplastic resins, for example, different thermoplastic resins are melt-extruded from two or more different extruders, and two or more kinds are made from a spinneret having a large number of spinning holes. Is discharged as a yarn in a state in which the thermoplastic resin is composited. Next, the discharged yarn is exposed to cold air controlled at 5 ° C to 20 ° C, and pulled by a pulling device while being cooled. The yarn coming out of the traction device is deposited on a transport conveyor and transported as a web. The webs being conveyed may be laminated to form a multilayer laminated nonwoven web. In the case of a multi-layered nonwoven fabric, each layer may be formed with a different fiber diameter, or a layer of fibers of a special form such as a modified cross-section yarn, a crimped fiber, or a hollow fiber may be laminated.

  For joining the nonwoven web, a method of joining with an adhesive, a method of joining with a low melting point fiber or a composite fiber, a method of spraying and melting a hot melt binder during web formation, a needle punch, a water stream, etc. For example, a method such as entanglement of fibers can be used, and there is no particular limitation. From the viewpoint of high-speed productivity, bonding may be performed by partial thermocompression bonding. For example, the web can be joined between heated emboss / flat rolls that can provide joining points such as pinpoint, ellipse, diamond, and rectangle. The thermocompression bonding area ratio in the partial thermocompression bonding is preferably 5 to 40%, more preferably 5 to 40%, from the viewpoint of maintaining strength and flexibility, maintaining the bulk of the nonwoven fabric, and preventing the uneven structure of the surface from being crushed between rolls. Is 5 to 25%.

  In addition, from the viewpoint of easily maintaining the characteristics of the nonwoven fabric surface structure and the thickness of the nonwoven fabric, especially in the case of a conjugate long fiber in which two or more kinds of thermoplastic resins are combined, the temperature is higher than the temperature at which the intersection of the fibers is melted and bonded. Any heating method can be used without particular limitation. Examples of the heating method include a hot air circulation type, a hot air penetration type, an infrared heater type, a method of blowing hot air on both surfaces of a nonwoven fabric, and a method of introducing hot air into a heated gas. And various heating methods can be used. From the viewpoint that more fiber adhesion points are obtained at the intersections of the fibers and the breaking strength of the nonwoven fabric is increased, heating with hot air is preferable, and a hot air penetration type is particularly preferable.

The temperature of the hot air in the hot air penetration type is preferably adjusted to a temperature suitable for a thermoplastic resin having a low melting point and contributing to bonding among the thermoplastic resins combined. For example, when the resin on the low melting point side of the two or more thermoplastic resins is polyethylene, a preferable hot air temperature is 120 to 155 ° C at which the polyethylene melts and adheres, preferably 135 to 155 ° C, more preferably 140 ° C. １５０150 ° C. When the bonding temperature is higher than 120 ° C., the bonding between the fibers is developed at the intersection of the fibers, and the strength as a nonwoven fabric can be realized. On the other hand, when the bonding temperature is 155 ° C. or higher, the solubility of the fibers becomes extremely high, and the texture becomes hard.
The velocity of the hot air is preferably 0.5 to 3.0 m / s, more preferably 0.7 to 2.5 m / s, and still more preferably 2.0 m / s or less. If the wind speed is low, the hot air does not penetrate in the thickness direction of the nonwoven fabric, and the strength is reduced. When the wind speed is high, the hot air penetrates, but the fibers are also crushed at the same time, resulting in a low-volume nonwoven fabric.

  As long as the surface structure of the nonwoven fabric is not adversely affected, the nonwoven web may be subjected to thermal bonding before the heat bonding by the hot air. From the viewpoint of productivity, it is preferable that the heat bonding be performed by passing through a pair of rolls of a combination of a metal embossing roll and a metal flat roll. From the viewpoint of maintaining the shape of the nonwoven web and the strength of the finally obtained nonwoven fabric, the emboss area ratio is preferably 5 to 30%, more preferably 5 to 20%, and still more preferably 6 to 15%. Further, the deeper the embossing depth is, the more the thickness of the nonwoven fabric can be maintained, preferably from 0.5 to 2.0 mm, more preferably from 0.7 to 1.5 mm. The emboss shape is not particularly limited, but is preferably a circular shape, an elliptical shape, a diamond shape, or a rectangular shape.

  The average fiber diameter of the fibers of the nonwoven fabric is preferably 8.0 μm or more and 38.0 μm or less, more preferably 9.0 μm or more and 33.5 μm or less, and still more preferably 11.0 μm or more and 26.5 μm or less. The average fiber diameter is preferably 8.0 μm or more from the viewpoint of spinning stability, and more preferably 38.0 μm or less from the viewpoint of the texture of the nonwoven fabric used for the sanitary material.

Basis weight of the nonwoven fabric is preferably 8 g / ^{m 2} or more 80 g / ^{m 2} or less, more preferably 10 g / ^{m 2} or more 40 g / ^{m 2} or less, further preferably 10 g / ^{m 2} or more 30 g / ^{m 2} or less. If a basis weight of 8 g / m ² or more, satisfy the strong as nonwoven fabric is used for sanitary materials, if 80 g / m ² or less, and satisfy the texture of the nonwoven fabric used for the sanitary materials, the appearance Does not give a thick impression.

  The height of the nonwoven fabric under no load is preferably 140 μm or more, more preferably 140 μm or more and 3000 μm or less, and still more preferably 140 μm or more and 2000 μm or less. From the viewpoint of the wetting and repelling performance of the nonwoven fabric and water permeability, the height under no load is preferably 140 μm or more, and when it exceeds 3000 μm, it gives an impression that the appearance is thick, and has rigidity and is used as a sanitary material. Is not suitable.

  The orientation index of the nonwoven fabric by X-ray CT is 0.43 or less, preferably 0.425 or less. When the orientation index determined by X-ray CT is within this range, the number of fibers occupying the thickness direction of the nonwoven fabric increases, and the bulk does not collapse even under a load, so that the nonwoven fabric has a bulky property. It is possible to obtain a hydrophilic bulky nonwoven fabric having a low bulk. The lower limit is preferably as low as possible, but the orientation index is preferably at least 0.30, more preferably at least 0.33.

The compression work amount WC of the nonwoven fabric of the present embodiment is preferably 0.20 gf · cm / cm ² or more and 1.00 gf · cm / cm ² or less, and more preferably 0.20 gf · cm / cm ² or more. It is 80 gf · cm · cm ² or less, and holding the compression work amount WC in this range can provide a cushioning property and an excellent wetting return index as a nonwoven fabric used for a sanitary material.

  The hydrophilic bulky nonwoven fabric of this embodiment contains or is coated with a water-permeable agent. As the water-permeable agent used, in consideration of safety to the human body, safety in the process, etc., higher alcohols, higher fatty acids, nonionic surfactants to which ethylene oxide such as alkylphenol is added, alkyl phosphate salts, Surfactants composed of an anionic surfactant such as an alkyl sulfate or the like alone or as a mixture. As the water-permeable agent, for example, polyether compounds, polyethylene ether-modified silicone, polyether-modified silicone, polyester compounds, polyamide compounds, polyglycerin compounds and the like are also preferably used.

  Existing methods such as kneading into fibers, coating method (gravure coater, kiss coater), spraying method, etc. can be used as a method for containing or applying a water-permeable agent, such as corona discharge treatment and atmospheric pressure plasma discharge treatment. May be adopted as necessary. As a drying method after the application, a known method using convection heat transfer, conduction heat transfer, radiation heat transfer, or the like can be employed, and a drying method using hot air or infrared rays, a drying method using thermal contact, or the like can be used.

  The amount of the water-permeable agent varies depending on the intended use. For example, for a sanitary material, the amount is preferably in the range of 0.10 wt% to 1.50 wt% with respect to the nonwoven fabric, and more preferably 0.15 wt%. % Or more and 1.20 wt% or less. If it is less than 0.10 wt%, satisfactory water permeability cannot be obtained, and if it exceeds 1.50 wt%, rash and eczema on the skin are likely to occur.

  The water-permeable agent may be diluted with a solvent such as water and applied as an aqueous solution. In order to prevent insufficient drying in the drying step due to the increase in the speed of the equipment, it is preferable that the application amount of the aqueous solution of the water-permeable agent is small. The application amount (wt%) to the nonwoven fabric is preferably 1.0 wt% or more and 65 wt% or less, more preferably 3.0 wt% or more and 60 wt% or less, and still more preferably 5.0 wt% or more. It is 50 wt% or less. If the content is less than 1.0 wt%, uniform coating cannot be obtained. On the other hand, if the content exceeds 65 wt%, the required drying capacity increases, equipment cost increases, and insufficient drying may occur.

For example, in the application of a water-permeable agent by a gravure coater, the pattern of the gravure roll may be a lattice type or a pyramid type, but is preferably a diagonal line type in which the water-permeable agent hardly remains on the gravure cell bottom. The cell volume is preferably 5 cm ³ / m ² or more and 40 cm ³ / m ² or less, and if it is less than 5 cm ³ / m ^2, it is difficult to apply uniformly because the applied amount is too small, and if it exceeds 40 cm ³ / m ² , Since the amount is too large, problems such as insufficient drying in the drying step and uneven adhesion of the water-permeable agent due to migration occur.
The gravure cell preferably has a depth of 10 μm or more and 80 μm or less, and an interval thereof is preferably designed to have the above cell volume within a range of preferably 80 mesh or more and 250 mesh or less.

  It can respond to high-speed equipment, can be applied efficiently, can be applied evenly in the thickness direction even with a thick nonwoven fabric, and can be uniformly applied even if the permeability of the water-permeable agent and the nonwoven fabric is slightly poor. In addition, since there is no step of passing the nonwoven fabric between the pair of rolls, it is preferable to apply a water-permeable agent by a spray method since the thickness of the nonwoven fabric is easily maintained. As the spraying method, a commonly known spraying method by air compression or a method of directly compressing and spraying a water-permeable agent aqueous solution may be used, but a rotor dampening method is particularly preferable from the viewpoint of uniform application to a nonwoven fabric. . By taking measures to prevent the aqueous permeating agent solution from scattering at the time of application, application is possible even at high speed of the equipment. The rotor dampening method is a method of supplying a water-permeable agent aqueous solution onto a rotating rotor and spraying the water-permeable agent aqueous solution using centrifugal force of the rotor rotation. In the rotor dampening method, the opening is limited so that the liquid particles of the aqueous solution of the water-permeable agent that are blown by the rotation of the rotor in the application direction can be sprayed only on the nonwoven fabric side to be applied, and can be uniformly applied in the CD direction of the nonwoven fabric. The diameter of the spray particles can be adjusted by the number of rotations of the rotor.

  In the case of the rotor dampening method, for example, a rotor having a diameter of 40 mm or more and 100 mm or less is selected, and the surface of the nonwoven fabric to be applied and the center of the rotor are applied so that the aqueous permeating agent solution can be uniformly attached in the CD direction of the nonwoven fabric to be applied. Set the distance of It is desirable that the setting is set so that one half of the application distribution range sprayed from the adjacent rotor is overlapped. Further, it is desirable that the rotors are arranged at equal intervals in a range of 60 mm or more and 220 mm or less in the CD direction, and it is preferable that the rotors have two stages.

The point of uniform application is that the spray particles reach the inside of the non-woven fabric to be applied. The spray particle size is preferably 0.010 mm or more and 0.200 mm or less, and more preferably 0.030 mm or more and 0.070 mm or less. preferable. The surface tension of the water-permeable agent aqueous solution is important for forming the optimum spray particle size, and the spray particle size is calculated by the following equation.
Sprayed particle diameter (μm) = {100,000 × {(surface tension (N / m))} / (rotor diameter (mm) × rotor rotation speed (rpm))

  Further, the temperature of the aqueous solution of the water-permeable agent in these coating methods is preferably from 5 ° C to 50 ° C, and more preferably from 12 ° C to 40 ° C from the viewpoint of uniform dispersion and stability of the solution. The viscosity of the water permeating agent aqueous solution is preferably 0.5 mPa · s or more and 50 mPa · s or less, and more preferably 0.8 mPa · s or more and 20 mPa · s or less from the viewpoint of easier uniform application. When the viscosity exceeds 50 mPa · s, the permeability of the aqueous solution of the water-permeable agent into the nonwoven fabric is inferior, and uniform application becomes difficult.

  A general drying method can be used for drying after application of the water-permeable agent aqueous solution, and is not particularly limited, and a known method using convection heat transfer, conduction heat transfer, radiation heat transfer, or the like is employed. Various drying methods can be used, such as a hot air circulation type, a hot air penetration type, an infrared heater type, a method of blowing hot air to both surfaces of a nonwoven fabric, and a method of introducing hot air into a heated gas.

The feature of the surface structure of the nonwoven fabric of the present embodiment is that, as shown in FIG. 1, the maximum height in a unit section defined by the X and Y directions when the measurement reference length on the nonwoven fabric surface is 100 μm, The ratio of the section that is 30% or more to the height (thickness) of the nonwoven fabric under no load is 50% or more per 40,000 sections corresponding to the nonwoven fabric surface area of 20 mm x 20 mm.
The measurement reference length and the maximum height on the nonwoven fabric surface are as follows. Using a digital microscope KH-8700 (manufactured by Hi-Rox), height information on the surface of the nonwoven fabric is measured and collected at an interval of 20 μm in each direction of 20 mm in the MD and 20 mm in the CD direction of the nonwoven. The height information obtained in the MD direction of the nonwoven fabric of 20 mm × CD direction of 20 mm was sectioned every 100 μm, and the sectioned length at this time was defined as a measurement reference length. The difference between the maximum value and the minimum value in the unit section was defined as the maximum height on the surface of the nonwoven fabric. The ratio of the maximum height to the non-loading height (thickness) of the nonwoven fabric was calculated from the maximum height (μm) / height without loading (μm) × 100.
That is, as the ratio of the section in which the ratio of the maximum height to the non-loaded height (thickness) of the nonwoven fabric is 30% or more is higher, the unevenness difference in the fine section of the nonwoven fabric surface is larger. In the present embodiment, the section in which the ratio of the maximum height to the height (thickness) of the nonwoven fabric with no load is 30% or more is defined as a measurement reference length of 100 μm in the MD direction 20 mm × CD direction 20 mm. 50% or more per 40,000 plots. By having such a feature of the structure of the nonwoven fabric surface, for example, regardless of the water-permeable agent imparted to the nonwoven fabric, when a liquid such as urine adheres to the nonwoven fabric surface, the contact angle is reduced, and Speeds up liquid transfer into the nonwoven fabric. From the viewpoint of liquid transferability of the nonwoven fabric, in the present embodiment, the ratio of the section whose maximum height is 30% or more to the height (thickness) of the nonwoven fabric at no load is 50% or more, and is preferably It is at least 52%, more preferably at least 55%, even more preferably at least 60%. When the ratio is within the range, good water permeability is exhibited. The higher the ratio, the better, but it is preferably 98% or less because the touch is deteriorated.

  The 45 ° inclined flow length value, which is an index of the water permeability of the nonwoven fabric of the present embodiment, is 25 mm or less, preferably 22 mm or less, more preferably 20 mm or less, and most preferably 18 mm or less. If the 45 ° permeation inclined flow length value exceeds 25 mm, for example, when used as a surface material such as a disposable diaper, the liquid flow on the surface increases and urine leakage easily occurs.

  The fourth durable water permeability index, which is an index of the water permeability of the nonwoven fabric of the present embodiment, is 85% or more. When the value of the durable permeability index for the fourth time is less than 85%, for example, when used for a surface material such as a disposable diaper, the surface material cannot be passed through a plurality of urinations and loses its function as a surface material. , It is easy to cause urine leakage.

  The wetting return index, which is an index of water permeability of the nonwoven fabric of the present embodiment, is preferably 0.8 g or less, more preferably 0.5 g or less. When the value of the re-wetting index exceeds 0.8 g, for example, when used as a surface material of a disposable diaper, when the surface material comes into contact with the skin, the skin feels very wet and the feeling of use deteriorates. The lower the wetting return index, the better, but a value of 0.01 g or less is the lower limit of measurement, and the measurement dispersion is large.

  Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to only the following Examples. In addition, the evaluation method of each characteristic is as follows, and the obtained physical properties are shown in Table 1 below. Hereinafter, the flow direction in the production of the nonwoven fabric is referred to as the MD direction, and the width direction perpendicular to the MD direction is referred to as the CD direction.

1. Average fiber diameter (μm)
A 1 cm square test piece was sampled by dividing the nonwoven fabric into five equal parts in the CD direction, and the diameter of each fiber was measured at 20 points each using a Keyence microscope VHX-700F, and the average value was calculated.

2. Nonwoven fabric weight (g / m ² )
According to JIS-L1906, five test pieces of 20 cm in the MD direction and 5 cm in the CD direction were sampled in the CD direction of the nonwoven fabric so that the sampling positions were equal, and the mass was measured. The average value was calculated as the weight per unit area. It was calculated as the basis weight (g / m ² ).

3. Non-load height (thickness) of non-woven fabric (μm)
Ten test pieces measuring 4 mm in the MD direction and 10 mm in the CD direction were arbitrarily sampled, and a photograph of the cross section of the nonwoven fabric was taken using SEM (VE-8800) manufactured by KEYENCE. Using the same image analysis software manufactured by KEYENCE, the obtained images were measured for five points in the thickness direction for each image, and the average value was taken as the height (thickness) (μm) under no load.

4. Maximum height on the surface of non-woven fabric (μm)
The nonwoven fabric is cut out and collected in an arbitrary direction in a square size of 20 mm × 20 mm. Next, using a 3D profile function of a digital microscope KH-8700 (manufactured by Hilox), height information on the surface of the nonwoven fabric is measured and collected at 20 mm in each side direction of the nonwoven fabric square at intervals of 20 μm in each direction. Height information obtained on each side of 20 mm × 20 mm of the square of the nonwoven fabric was sectioned every 100 μm, and the sectioned length at this time was defined as a measurement reference length. The difference between the maximum value and the minimum value in the section was defined as the maximum height on the surface of the nonwoven fabric. This measurement procedure is schematically shown in FIG.
The ratio of the maximum height on the surface of the nonwoven fabric to the height (thickness) (μm) of the nonwoven fabric with no load was calculated by the following formula: maximum height (μm) / height (thickness) with no load (μm) × 100.
Furthermore, the number of sections where the ratio of the maximum height to the height (thickness) of the nonwoven fabric when there is no load is 30% or more is defined as a measurement reference length of 100 μm in each side direction of 20 mm × 20 mm of the square of the nonwoven fabric. The ratio (%) was calculated by dividing by the number of sections.

5. Orientation index (X-ray CT)
A test piece of 5 mm in the MD direction × 5 mm in the CD direction was arbitrarily cut, and measured in a visual field of about 3 mm × 3 mm at the time of image analysis. The measurement was performed using a high-resolution 3DX X-ray microscope nano3DX (manufactured by Rigaku Corporation) and CT measurement using low-energy, high-brightness X-rays capable of obtaining contrast even with light elements. Detailed conditions are shown below.
X-ray target: Cu
X-ray tube voltage: 40 kV
X-ray tube current: 30 mA
Lens: 1.08 μm / pix
Binning: 2
Rotation angle: 180 °
Number of projections: 1000 Exposure time: 10 seconds / frame Number of camera pixels: 3300 × 2500
Reconstruction: Feldkamp method The three-dimensional tomogram obtained by the CT measurement was subjected to image analysis, and orientation indexes Ix, Iy, Iz of three orthogonal axes (x, y, z) were obtained. The thickness direction of the sample to be mainly evaluated was matched with the z direction. Here, the orientation indices Ix, Iy, and Iz are the sum of the area of the fiber surface viewed from each of the x, y, and z directions (the sum of the total projected area of the fiber surface in each direction), Ax, Ay, respectively. , Az,
Ix = Ax / (Ax + Ay + Az)
Iy = Ay / (Ax + Ay + Az)
Iz = Az / (Ax + Ay + Az)
Defined. Ax, Ay, and Az were determined from tomograms. In this index, it is oriented in the direction of smaller value. In the case of an isotropic structure, it is 1/3 in all cases.

6. Compression work (WC)
Five test pieces of 5 cm square in the CD direction were sampled and measured using a compression tester (KES-G5) manufactured by Kato Tech. The test piece was placed on a metal sample stand and compressed between steel plates having a circular flat surface with a pressurized area of 2 cm ² . The compression speed was 0.067 mm / s, and the maximum compression load was 3.4 kPa (35 gf / cm ² ). The recovery process was also measured at the same speed, and the average value of the compression work was calculated.

7. Number of crimps (pcs / 2.54 cm (inch))
A 5 cm square test piece was sampled by dividing the nonwoven fabric in the CD direction by 5 equal parts, and five fibers were selected in a state in which no load was applied to the fibers using a Keyence microscope VH-Z450, and a length per inch was selected. The number of crimps was measured, and the number of crimps (pieces / inch) was calculated from the average value.

8. 45 ° water permeability gradient flow length value (mm)
Ten sheets of toilet paper (Hard Single 1R55m, manufactured by Itoman Co., Ltd.) are stacked on a board inclined at 45 degrees, and a test cloth (20 cm square) is placed on the toilet paper and set, and a height of 10 mm above the cloth is set. , 0.1 cc of physiological saline was added dropwise. The distance from which the physiological saline flowed down from the dropping position to the end of absorption was read. This measurement was arbitrarily performed at 20 points in the test cloth, and the average value thereof was defined as a 45 ° water permeability inclined flow length value (mm).

9. Durability permeability index (%)
Ten sheets of toilet paper (Hard Single 1R55m, manufactured by Itoman Co., Ltd.) are stacked as an absorber, and a test cloth (20 cm × 30 cm) is placed thereon. Further, a stainless steel plate in which 10 holes of 1.5 cm in diameter were opened at equal intervals was placed thereon, and 0.3 cc of physiological saline was dropped from a height of 10 mm above the cloth located in each hole. After a lapse of minutes, the solution is again dropped. After the third drop, the number of holes (A) absorbed within 10 seconds is counted. This was tested at 40 locations of the same sample and {((A) / (10 holes × 40 samples) × 100)} was taken as the third permeability endurance index (%). Also, after the fourth dropping, the number of holes (B) absorbed within 10 seconds is counted as in the third drop, and Δ ((B) / (10 holes × 40 samples) × 100)と し た was taken as the fourth permeability endurance index (%).

10. Rewetting index (g)
A test cloth is placed on three specific filter papers (GRADE: 989 manufactured by Ahlstrom) in order to keep the characteristics of the absorber as an absorber. A plate (about 800 g) with a 10 cm square hole with a diameter of 25 mm in the center is placed on top of it, and physiological saline (3.5 times the weight of the absorber) is dropped from the height of 25 mm above the center hole. And absorb. Next, the plate on the test cloth is removed, and a 3.5 kg weight (10 cm square) is gently placed thereon for 3 minutes to stabilize the liquid distribution in the absorber. Next, the 3.5 kg weight is once removed, and two filter papers (12.5 cm square, ERTMWWSSHEETS manufactured by HOLLINGSWORTH & VOSE.CONPANY) weighed in advance are quickly placed on the test cloth, and the 3.6 kg weight is gently placed again. . After 2 minutes, the weight gain of the measurement filter paper is weighed. The value (g) of the increase was defined as a rewetting index.

11. Application amount of water permeating agent aqueous solution (wt%)
The value calculated by the following equation from the consumption amount of the aqueous solution of the water-permeable agent for one hour of the water-permeable imparting process was defined as the application amount (wt%) of the aqueous solution of the water-permeable agent.
Coating amount (wt%) = consumption amount of aqueous permeating agent solution (g) / {non-woven fabric weight (g / m ² ) × width (m) × processing speed (m / min) × 60 (min)} × 100

12. Amount of pure water permeant (wt%)
The weight (W1) of the nonwoven fabric sample to which the water-permeable agent was conditioned at a temperature and humidity of 25 ° C. × 40% RH for 24 hours and the weight (W2) of the water-permeable agent obtained by Soxhlet extraction from this nonwoven fabric sample using methanol. Was measured, and the attached amount C (wt%) of the pure water-permeable agent was determined by the following equation.
C (wt%) = [W2 / W1] × 100
Sampling of the nonwoven fabric sample is performed at 5 locations at 30 cm intervals in the MD direction and 5 locations at equal intervals within the width of the nonwoven fabric in the CD direction at a length such that the nonwoven fabric sample is about 2 g in a range of 5 cm to 10 cm. , A total of 10 test cloths are collected. The above measurements were performed, and the average value thereof was defined as the amount of pure water permeating agent attached (wt%).

13. Dispersion The nonwoven fabric was sampled at 50 cm × 50 cm, and the appearance of the nonwoven fabric was rated by visual evaluation according to the following evaluation criteria. From the viewpoint of the evaluation of the dispersion, it was determined whether the spots such as streaks had no regularity, and whether the single yarns were uniformly spread (whether or not they were clumped). Higher grades indicate better dispersion.
5: Very good 4: Good 3: Normal (level that can be used as a product)
2: Bad 1: Very bad

[Example 1]
A polypropylene (PP) resin having an MFR of 55 g / 10 minutes (measured at a temperature of 230 ° C. and a load of 2.16 kg according to JIS-K7210) is used as the first component, and an MI of 26 g / 10 minutes (temperature according to JIS-K7210) A high-density polyethylene (HDPE) resin (measured at 190 ° C. under a load of 2.16 kg) is used as the second component, and the discharge amount of the first component is 0.4 g / min · hole and the discharge amount of the second component is 0.4 g / min. A fiber having a total discharge amount of 0.8 g / min · hole in minute / hole and a ratio of the first component to the second component of 1/1 is extruded at a spinning temperature of 220 ° C. by a spun bond method. An eccentric sheath-core composite long fiber web having an average fiber diameter of 17.9 μm was prepared by extruding the moving collection surface at a spinning speed of 3200 m / min using a high-speed airflow traction device using an air jet.
Then, the fibers of the obtained web were bonded to each other by hot air at a hot air temperature of 142 ° C. and a hot air speed of 0.7 m / s to obtain a composite long-fiber nonwoven fabric having a basis weight of 18 g / m ² and a number of crimps of 15 pieces / inch.
Next, a 3 wt% aqueous solution of a water-permeable agent comprising a mixture of hexaglycerin monostearate, a polyether-modified silicone and a polyoxyalkylene castor oil ether was used as the water-permeable agent aqueous solution in the obtained nonwoven fabric at a liquid temperature of 20 ° C. and a liquid viscosity of 3. It was adjusted to 2 mPa · s, and applied to the nonwoven fabric by a rotor dampening method so that the application amount was 10 wt%. The diameter of the rotor used was 80 mm, and each rotor was arranged at intervals of 115 mm in the CD direction such that the distance between the center of the rotor and the nonwoven fabric to be applied was 180 mm. Further, the number of rotations of the rotor was adjusted so that the spray particle size of the sprayed water-permeable agent aqueous solution was 35 μm.
The percentage of the section where the maximum height in the section when the measurement reference length is 100 μm on the surface of the obtained nonwoven fabric is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 85%. The 45-degree inclined flow length value of the nonwoven fabric was 16 mm, the fourth durable water permeability index was 99%, and the rewetting index was 0.12 g. The results are shown in Table 1 below.

[Example 2]
In the same manner as in Example 1, an eccentric sheath-core composite long-fiber nonwoven fabric having an average fiber diameter of 17.9 μm, a basis weight of 10 g / m ² , and a number of crimps of 15 pieces / inch was obtained. Next, the same aqueous permeating agent solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same application conditions.
The ratio of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 87%. The 45 ° water permeability inclined flow length value of the nonwoven fabric was 14 mm, the fourth durable water permeability index was 99%, and the rewetting index was 0.50 g. The results are shown in Table 1 below.

[Example 3]
The discharge amount of the first component is 0.54 g / min · hole, the discharge amount of the second component is 0.26 g / min · hole, and the total discharge amount is 0.80 g / min · hole. An eccentric sheath-core composite long fiber web having an average fiber diameter of 17.9 μm was prepared in the same manner as in Example 1 except that the ratio of the components was about 2/1.
The obtained eccentric sheath-core type composite long fiber web is bonded to each other by hot air at a hot air temperature of 145 ° C. and a hot air speed of 1.0 m / s to form a composite having a basis weight of 18 g / m ² and a number of crimps of 10 / inch. A long-fiber nonwoven fabric was obtained.
Next, the same water-permeable agent aqueous solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section where the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 74%. The 45-degree inclined flow length value of the nonwoven fabric was 16 mm, the fourth durable permeability index was 99%, and the rewetting index was 0.12 g. The results are shown in Table 1 below.

[Example 4]
In the same manner as in Example 3, a composite long-fiber nonwoven fabric having an average fiber diameter of 17.9 μm, a basis weight of 18 g / m ² , and a number of crimps of 10 / inch was obtained.
A 1 wt% aqueous solution of a water-permeable agent is adjusted to the obtained composite long-fiber nonwoven fabric by a gravure coating method at a liquid temperature of 20 ° C. and a liquid concentration of 2.3 mPa · s. The coating was performed using a gravure roll having a mesh size of 120 mesh and a cell volume of 22 cm ³ / m ² , and then dried and wound up through a cylinder dryer at 120 ° C.
The ratio of the section where the maximum height in the section when the measurement reference length is 100 μm on the surface of the obtained nonwoven fabric is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 70%. The 45-degree inclined flow length value of the nonwoven fabric was 17 mm, the fourth durable permeability index was 97%, and the rewetting index was 0.22 g. The results are shown in Table 1 below.

[Example 5]
The first component is the same polypropylene resin as in Example 1, and the second component is a linear low-density polyethylene having an MI of 16.8 g / 10 min (measured at a temperature of 190 ° C. and a load of 2.16 kg according to JIS-K7210). (LLDPE) resin, the discharge amount of the first component is 0.54 g / min · hole, the discharge amount of the second component is 0.26 g / min · hole, and the total discharge amount is 0.8 g / min · hole. A fiber having a ratio of the first component to the second component of about 2/1 is extruded at a spinning temperature of 220 ° C. by a spun bond method, and the filament group is directed to a moving collecting surface by using a high-speed airflow traction device by an air jet. And extruded to prepare an eccentric sheath-core type long fiber web having an average fiber diameter of 20.5 μm.
The obtained eccentric sheath-core long-fiber web is bonded to each other by hot air at a hot air temperature of 150 ° C. and a hot air velocity of 0.3 m / s to form a composite long fiber having a basis weight of 18 g / m ² and a number of crimps of 40 pieces / inch. A non-woven fabric was obtained.
Next, the same water-permeable agent aqueous solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 92%. The 45-degree inclined flow length value of the nonwoven fabric was 15 mm, the fourth durable permeability index was 99%, and the rewetting index was 0.35 g. The results are shown in Table 1 below.

[Example 6]
In the same manner as in Example 5, an eccentric sheath-core composite long-fiber nonwoven fabric having an average fiber diameter of 20.5 μm, a basis weight of 18 g / m ² , and a number of crimps of 40 pieces / inch was obtained. Next, the same water-permeable agent aqueous solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same application conditions except that the concentration of the water-permeable agent aqueous solution was 5 wt%.
The ratio of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 92%. The 45 ° water permeability inclined flow length value of the nonwoven fabric was 13 mm, the fourth durable water permeability index was 99%, and the wettability index was 0.47 g. The results are shown in Table 1 below.

[Example 7]
An eccentric sheath-core composite continuous fiber web having an average fiber diameter of 17.9 μm was prepared in the same manner as in Example 1.
Next, the obtained eccentric sheath-core type composite long fiber nonwoven web was flat rolled and embossed at 100 ° C. (pattern specifications: 1.00 mm diameter circle, staggered arrangement, horizontal pitch 4.4 mm, vertical pitch 4.4 mm, (The pressure-bonding area ratio is 7.9%), and the fibers are temporarily bonded to each other. Then, the fibers are bonded to each other by hot air at a hot air temperature of 142 ° C. and a hot air speed of 0.7 m / s, and the basis weight is 18 g / m ² . A composite long-fiber nonwoven fabric with a shrinkage of 17 pieces / inch was obtained.
Next, the same water-permeable agent aqueous solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section where the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more with respect to the height (thickness) of the nonwoven fabric under no load is 72%. The 45-degree inclined flow length value of the nonwoven fabric was 18 mm, the fourth durable permeability index was 95%, and the rewetting index was 0.18 g. The results are shown in Table 1 below.

Example 8
In the same manner as in Example 7, an eccentric sheath-core composite long-fiber nonwoven fabric having an average fiber diameter of 17.9 μm, a basis weight of 8 g / m ² , and a crimp count of 17 / inch was obtained. Next, the same water-permeable agent aqueous solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section where the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 74%. The 45-degree inclined flow length value of the nonwoven fabric was 16 mm, the fourth durable water permeability index was 97%, and the rewetting index was 0.42 g. The results are shown in Table 1 below.

[Example 9]
Using the same components as in Example 1, the discharge amount of the first component is 0.40 g / min · hole, the discharge amount of the second component is 0.40 g / min · hole, and the total discharge amount is 0.8 g / min. A fiber which was hollow and had a ratio of the first component to the second component of 1/1 was extruded at a spinning temperature of 220 ° C. by a spun bond method. This filament group was extruded at a spinning speed of 3200 m / min toward a moving collection surface by using a high-speed airflow traction device using an air jet to prepare a side-by-side type composite continuous fiber web having an average fiber diameter of 17.9 μm.
Next, the obtained side-by-side type composite continuous fiber web was adhered to each other in the same manner as in Example 7 to obtain a composite continuous fiber nonwoven fabric having a basis weight of 18 g / m ² and a crimp count of 23 pieces / inch. Next, the same aqueous permeating agent solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section where the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric in the unloaded state is 76%. The 45-degree inclined flow length value of the nonwoven fabric was 15 mm, the fourth durable permeability index was 99%, and the rewetting index was 0.15 g. The results are shown in Table 1 below.

Example 10
The first component was polyethylene terephthalate (PET) having a solution viscosity ηsp / c of 0.75, the second component was high density polyethylene (HDPE) as in Example 1, and the discharge rate of the first component was 0.54 g / min. When the discharge amount of the hole and the second component is 0.26 g / min · hole, the total discharge amount is 0.80 g / min · hole, and the ratio of the first component to the second component is about 2/1. The filaments are extruded at a spinning temperature of 295 ° C. by a spun bond method, and the filaments are extruded toward a moving collecting surface using a high-speed airflow traction device by an air jet, and the eccentric sheath-core composite filament having an average fiber diameter of 18.7 μm. A web was prepared.
The obtained eccentric sheath-core composite continuous fiber web was bonded to the fibers in the same manner as in Example 1 to obtain a composite continuous fiber nonwoven fabric having a basis weight of 18 g / m ² and a crimp count of 20 pieces / inch.
Next, the same aqueous permeating agent solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same application conditions.
The ratio of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 87%. The 45-degree inclined flow length value of the nonwoven fabric was 15 mm, the fourth durable permeability index was 99%, and the rewetting index was 0.15 g. The results are shown in Table 1 below.

[Example 11]
Using the same components as in Example 1, the discharge amount of the first component is 0.24 g / min · hole, the discharge amount of the second component is 0.56 g / min · hole, and the total discharge amount is 0.8 g / min. An eccentric sheath-core type composite continuous fiber web having an average fiber diameter of 17.9 μm is prepared in the same manner as in Example 1 except that the mixture is hollow and the ratio of the first component to the second component is 3/7. did.
The obtained eccentric sheath-core type composite continuous fiber web was bonded to each other in the same manner as in Example 1 to obtain a composite continuous fiber nonwoven fabric having a basis weight of 18 g / m ² and a crimp count of 17 pieces / inch. Next, the same water-permeable agent aqueous solution as in Example 4 was applied to the obtained composite long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section where the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric in the unloaded state is 70%. The 45-degree inclined flow length value of the nonwoven fabric was 18 mm, the fourth durable permeability index was 95%, and the rewetting index was 0.18 g. The results are shown in Table 1 below.

[Example 12]
Using the same components as in Example 1, the discharge amount of the first component is 0.16 g / min · hole, the discharge amount of the second component is 0.64 g / min · hole, and the total discharge amount is 0.8 g / min. An eccentric sheath-core composite continuous fiber web having an average fiber diameter of 18.7 μm is prepared in the same manner as in Example 1 except that the mixture is hollow and the ratio of the first component to the second component is 1: 4. did.
The obtained eccentric sheath-core type composite continuous fiber web was bonded to each other in the same manner as in Example 1 to obtain a composite continuous fiber nonwoven fabric having a basis weight of 18 g / m ² and a crimp count of 5 pieces / inch. Next, the same aqueous permeating agent solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same application conditions.
The ratio of the section where the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric in the unloaded state is 52%. The 45 ° -permeability inclined flow length value of the nonwoven fabric was 22 mm, the fourth durable water permeability index was 85%, and the wet-back index was 0.45 g. The results are shown in Table 1 below.

Example 13
Using the same components as in Example 1, the discharge amount of the first component is 0.40 g / min · hole, the discharge amount of the second component is 0.40 g / min · hole, and the total discharge amount is 0.8 g / min. A fiber which was hollow and had a ratio of the first component to the second component of 1: 1 was extruded at a spinning temperature of 220 ° C. by a spun bond method. The extruded filaments are drawn in the traction zone by using the suction force of the moving collecting surface, and then are deposited on the moving collecting surface through a diffuser to form a side-by-side composite long fiber web having an average fiber diameter of 20.5 μm. Was prepared.
Then, the obtained side-by-side type composite continuous fiber web was bonded to each other in the same manner as in Example 1 to obtain a composite continuous fiber nonwoven fabric having a basis weight of 18 g / m ² and a crimp count of 25 pieces / inch. Next, the same water-permeable agent aqueous solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same coating conditions.
The proportion of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric in the unloaded state is 90%. The 45 ° -permeability inclined flow length value of the nonwoven fabric was 14 mm, the fourth durable water-permeability index was 99%, and the rewetting index was 0.17 g. The results are shown in Table 1 below.

[Example 14]
In the same manner as in Example 13, an eccentric sheath-core composite long-fiber nonwoven fabric having an average fiber diameter of 20.5 μm, a basis weight of 30 g / m ² , and a crimp count of 25 / inch was obtained. Next, the same aqueous permeating agent solution as in Example 1 was applied to the obtained composite long-fiber nonwoven fabric under the same application conditions.
The ratio of the section where the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 89%. The 45 ° water permeability inclined flow length value of the nonwoven fabric was 14 mm, the fourth durable water permeability index was 99%, and the rewetting index was 0.12 g. The results are shown in Table 1 below.

[Example 15]
Polypropylene (PP) having an MFR of 38 g / 10 min is extruded at a spinning temperature of 240 ° C. and a discharge rate of 0.80 g / min · hole using a spinneret having a C-shaped nozzle, and the filament group is air jetted. Using a high-speed airflow traction device, the fiber was extruded toward a moving collection surface to obtain a long fiber web having an average fiber diameter of 18.7 μm.
Then, the obtained long fiber web was flat roll and emboss roll set at a temperature of 135 ° C. and a pressure of 60 kg / cm (pattern specifications: 0.425 mm diameter circle, staggered arrangement, horizontal pitch 2.1 mm, vertical pitch 1.1 mm, The fibers were partially adhered to each other by passing through a press-bonded area ratio of 6.3% to obtain a long-fiber nonwoven fabric having a basis weight of 25 g / m ² and a crimp count of 28 pieces / inch.
Next, the same water-permeable agent aqueous solution as in Example 4 was applied to the obtained long-fiber nonwoven fabric under the same coating conditions.
The proportion of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 55%. The 45 ° -permeability inclined flow length value of the nonwoven fabric was 23 mm, the fourth durability water-permeability index was 89%, and the wet-back index was 0.12 g. The results are shown in Table 1 below.

[Comparative Example 1]
A polypropylene (PP) resin having an MFR of 55 g / 10 minutes (measured at a temperature of 230 ° C. and a load of 2.16 kg according to JIS-K7210) is extruded as a single component at a spinning temperature of 220 ° C. by a spun bond method. Using a high-speed airflow traction device using an air jet, the fiber was extruded toward the moving collecting surface to prepare a long fiber web having an average fiber diameter of 17.9 μm.
Next, the obtained web was subjected to flat roll and emboss roll at 141 ° C. (pattern specification: 0.425 mm diameter circle, staggered arrangement, horizontal pitch 2.1 mm, vertical pitch 1.1 mm, compression area ratio 6.3%). The fibers were adhered to each other through the gap to obtain a long-fiber nonwoven fabric in which a fiber having a basis weight of 18 g / m ² was not crimped.
Next, the same water-permeable agent aqueous solution as in Example 4 was applied to the obtained long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 40%. The 45 ° -permeability inclined flow length value of the nonwoven fabric was 28 mm, the fourth durable water permeability index was 74%, and the wet-back index was 0.56 g. The results are shown in Table 2 below.

[Comparative Example 2]
The continuous-fiber nonwoven fabric obtained in Comparative Example 1 is a continuous honeycomb-shaped pattern having a side of 0.9 mm and a line width of 0.1 mm (concave pattern) (press area ratio: 12.5%, pattern pitch: vertical 2.8 mm, The pattern was passed between an embossing roll (width of 3.2 mm, depth of 0.7 mm) (80 ° C.) and a rubber roll having a surface hardness of 60 degrees (JIS-A hardness), and a pattern was pressed with a pressure of ² kg / cm ² . A flexible long-fiber nonwoven fabric was obtained in which the periphery of the tortoise shell was pressed to have a high-density region and the center was raised.
Next, the same water-permeable agent aqueous solution as in Example 4 was applied to the obtained long-fiber nonwoven fabric under the same coating conditions.
The ratio of the section in which the maximum height in the section when the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 42%. The 45 ° -permeability inclined flow length value of the nonwoven fabric was 27 mm, the fourth durable water-permeability index was 80%, and the wet-back index was 0.68 g. The results are shown in Table 2 below.

[Comparative Example 3]
Using the same components as in Example 1, the discharge amount of the first component is 0.72 g / min · hole, the discharge amount of the second component is 0.08 g / min · hole, and the total discharge amount is 0.8 g / min. A fiber which is hollow and has a ratio of the first component to the second component of 9/1 is extruded by a spun bond method at a spinning temperature of 220 ° C., and the filament group is moved by using a high-speed airflow traction device by an air jet. The mixture was extruded toward the collecting surface to prepare an eccentric sheath-core composite long fiber web having an average fiber diameter of 16.7 μm.
Next, the obtained eccentric sheath-core type composite continuous fiber web was bonded to each other by hot air at a hot air temperature of 142 ° C. and a hot air speed of 0.7 m / s, and the basis weight was 18 g / m ² and the number of crimps was 0 / inch. A composite long-fiber nonwoven fabric was obtained.
Next, the same aqueous permeating agent solution as in Example 4 was applied to the obtained composite long-fiber nonwoven fabric under the same application conditions.
When the measurement reference length on the surface of the obtained nonwoven fabric is 100 μm, the maximum height in the compartment is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied. The 45 ° water permeability inclined flow length value of the nonwoven fabric was 28 mm, the fourth durability water permeability index was 64%, and the wettability index was 0.52 g. The results are shown in Table 2 below.

[Comparative Example 4]
Using the same components as in Example 1, the discharge amount of the first component is 0.54 g / min · hole, the discharge amount of the second component is 0.26 g / min · hole, and the total discharge amount is 0.8 g / min. A fiber which is hollow and has a ratio of the first component to the second component of 2/1 is extruded by a spun bond method at a spinning temperature of 220 ° C., and the filament group is moved by using a high-speed airflow traction device by an air jet. The mixture was extruded toward the collection surface to prepare a sheath-core composite continuous fiber web having an average fiber diameter of 16.7 μm.
Then, in the resulting web same method and conditions as in Comparative Example 3, after bonding the fibers, the permeability agent solution was applied, basis weight 18 g / m ^2, crimp number 0 / inch composite long fiber nonwoven fabric I got
The ratio of the section where the maximum height in the section when the measurement reference length is 100 μm on the surface of the obtained nonwoven fabric is 30% or more of the height (thickness) of the nonwoven fabric when no load is applied is 46%. The 45-degree inclined flow length value of the nonwoven fabric was 26 mm, the fourth durable permeability index was 73%, and the rewetting index was 0.60 g. The results are shown in Table 2 below.

  Since the hydrophilic bulky nonwoven fabric of the present invention has excellent water permeability, it can be suitably used for manufacturing sanitary materials. The sanitary material can be suitably used as a top sheet on the surface of a disposable diaper, sanitary napkin or incontinence pad. Further, the hydrophilic bulky nonwoven fabric of the present invention is not limited to the above-mentioned applications, and includes, for example, a mask, a warmer, a tape base cloth, a patch base cloth, a first aid base cloth, a packaging material, a wipe product, a medical gown, a bandage, It can also be used for clothing and skin care sheets.

That is, the present invention is as follows.
[1] A hydrophilic bulky nonwoven fabric composed of thermoplastic long fibers having a number of crimps of 5 to 45 pieces / 2.54 cm (inch), in the X direction when the measurement reference length on the surface of the nonwoven fabric is 100 μm The proportion of the section in which the maximum height in the unit section defined by the Y direction is 30% or more with respect to the height (thickness) of the nonwoven fabric in the Z direction at no load corresponds to the nonwoven fabric surface area of 20 mm × 20 mm. The above-mentioned hydrophilic bulky nonwoven fabric having a nonwoven fabric surface structure of 50% or more per 40,000 sections and containing or applying a water-permeable agent . [2] The hydrophilic bulky nonwoven fabric according to the above [1], wherein the hydrophilic bulky nonwoven fabric has an orientation index in the thickness direction by X-ray CT of 0.43 or less.
[3] The hydrophilic bulky nonwoven fabric according to [1] or [2], wherein the work of compression of the hydrophilic bulky nonwoven fabric is 0.20 gf · cm / cm ² or more and 1.00 gf · cm / cm ² or less.
[4] The hydrophilic bulky nonwoven fabric according to any of [1] to [3], wherein the thermoplastic fiber is a side-by-side type or an eccentric sheath-core type composite fiber.
[5] The hydrophilic bulky nonwoven fabric according to any one of [1] to [4], wherein the thermoplastic fiber is a polyolefin-based fiber.
[6] The water-permeable material is at least one surfactant selected from the group consisting of higher alcohols, higher fatty acids, nonionic surfactants to which ethylene oxide is added, alkyl phosphate salts, and anionic surfactants. The bulky hydrophilic nonwoven fabric according to any one of the above [1] to [5].
[7] The water-permeable agent is at least one surfactant selected from the group consisting of a polyether compound, a polyethylene ether-modified silicone, a polyether-modified silicone, a polyester compound, a polyamide compound, and a polyglycerin compound. The hydrophilic bulky nonwoven fabric according to any one of [1] to [5].
[8] The hydrophilic bulky nonwoven fabric according to any of [4] to [7], wherein the intersections of the conjugate fibers are melted and adhered.
[9] The hydrophilic bulky nonwoven fabric according to any one of [1] to [8], which is partially thermocompression-bonded.
[ 10 ] A sanitary material comprising the hydrophilic bulky nonwoven fabric according to any one of [1] to [ 9 ].

Claims (6)

  A hydrophilic bulky nonwoven fabric made of thermoplastic filaments having a number of crimps of 5 to 45 pieces / 2.54 cm (inch), which is determined in the X and Y directions when the measurement reference length on the surface of the nonwoven fabric is 100 μm. The ratio of the section in which the maximum height in the specified unit section is 30% or more to the height (thickness) of the nonwoven fabric in the Z direction at no load is 40,000, the number of the sections corresponding to the nonwoven fabric surface area of 20 mm × 20 mm. The hydrophilicity is characterized by having a nonwoven fabric surface structure of not less than 50% per unit, a 45 ° water permeability gradient flow length value of the nonwoven fabric being 25 mm or less, and a fourth durable water permeability index of 85% or more. Bulk nonwoven fabric.   The hydrophilic bulky nonwoven fabric according to claim 1, wherein the hydrophilic bulky nonwoven fabric has an orientation index in a thickness direction by X-ray CT of 0.43 or less. 3. The hydrophilic bulky nonwoven fabric according to claim 1, wherein a compression work amount of the hydrophilic bulky nonwoven fabric is 0.20 gf · cm / cm ² or more and 1.00 gf · cm / cm ² or less. 4.   The hydrophilic bulky nonwoven fabric according to any one of claims 1 to 3, wherein the thermoplastic fiber is a conjugate fiber of a side-by-side type or an eccentric sheath-core type.   The hydrophilic bulky nonwoven fabric according to any one of claims 1 to 4, wherein the thermoplastic fiber is a polyolefin-based fiber.   A sanitary material using the hydrophilic bulky nonwoven fabric according to any one of claims 1 to 5.

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