WO2024203398A1 - Long-fiber nonwoven fabric, method for manufacturing same, and sanitary material - Google Patents

Abstract

In order to provide a long-fiber nonwoven fabric having a smooth surface without pleats and having good stretchability, at least one surface of a long-fiber nonwoven fabric according to the present invention is composed of fibers F_A having a thermoplastic resin A as a main component, the ratio D_max/D_min of the apparent maximum fiber diameter D_max (μm) and the apparent minimum fiber diameter D_min (μm) of the fiber F_A is 1.2-5.0, the elongation recovery rate of the long-fiber nonwoven fabric is 50%-99%, and the apparent density is 0.02 g/cm³-0.20 g/cm³. The long-fiber nonwoven fabric is preferably used for a sanitary material.

Description

Long-fiber nonwoven fabric, its manufacturing method, and sanitary material

The present invention relates to a long-fiber nonwoven fabric, its manufacturing method, and a sanitary material.

In sanitary materials such as disposable diapers and sanitary napkins, elastic materials that need to elastically fit the skin around the waist and thighs are generally required to have good elasticity (the ability to stretch and shrink well) and to be soft to the touch.

Traditionally, elastic materials have been widely made up of elastic threads bonded to slack non-stretchable nonwoven fabric. However, in such elastic materials, although the slack non-stretchable nonwoven fabric covers the elastic threads, which have a sticky feel (hereinafter also referred to as "rubber touch"), the pleats (hereinafter also referred to as "gathers") caused by the slack in the non-stretchable nonwoven fabric cause uneven tightening force from the elastic threads, making it difficult to achieve a comfortable feel against the skin.

In response to this problem, Patent Document 1 proposes a stretchable nonwoven fabric obtained by stretching a fiber sheet in which substantially inelastic inelastic fiber layers made of continuous fibers formed by the spunbonding method are arranged on each side of an elastic fiber layer made of continuous fibers formed by the spunbonding method, and then relaxing the stretching to exhibit stretchability. In addition, Patent Document 2 proposes a nonwoven fabric laminate in which a nonwoven fabric made of crimped fibers is laminated on at least one side of a mixed fiber spunbonded nonwoven fabric containing long fibers of a thermoplastic elastomer (A) and long fibers of a thermoplastic resin (B).

JP 2007-321293 A International Publication No. WO 2008/108238

However, to obtain a stretchable nonwoven fabric as described in Patent Document 1, the inelastic fiber layer can only be stretched to the extent that it can be stretched in the drawing process, and the fibers break when stretched beyond the elastic deformation region, making it difficult to obtain good stretchability. Furthermore, when interlacing and bonding is performed using air-through (hot air) as described in Patent Document 1, the number of bonding points between the fibers is greater than when bonding is performed using a hot embossing roll, which is commonly used in the spunbond method, and deformation between the bonding points is suppressed, making it difficult to obtain good stretchability from this perspective as well.

In addition, as described in Patent Document 2, a technique of laminating a mixed fiber spunbonded nonwoven fabric containing long fibers of a thermoplastic elastomer (A) and long fibers of a thermoplastic resin (B) with a nonwoven fabric made of crimped fibers, and then stretching the laminate to exhibit elasticity, makes it easy to stretch in the stretching process due to the slackness of the crimp, but the effect is difficult to obtain unless the distance between the convex parts of the hot embossing roll (corresponding to the fused parts of the spunbonded nonwoven fabric) is greater than the crimp, and on the other hand, if this distance is too great, there is an issue that handling is difficult due to surface fuzzing and low strength.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a long-fiber nonwoven fabric that has a smooth surface without pleats and has good elasticity.

As a result of intensive research conducted by the inventors to achieve the above object, they discovered that in a long-fiber nonwoven fabric having an apparent fiber diameter within a specific range, the interactions between the fibers are appropriately controlled to obtain dimensional stability, and they have come to the realization that good stretchability can be achieved. Furthermore, they discovered that this long-fiber nonwoven fabric is very bulky, and is fluffy yet firm to the touch.

The present invention has been completed based on these findings, and provides the following inventions:

[1] A long-fiber nonwoven fabric, at least one surface of which is composed of fibers F _A mainly composed of thermoplastic resin A, wherein the ratio D _max /D _min of the apparent maximum fiber diameter D _max (μm) to the apparent minimum fiber diameter D _min (μm) of the fibers F _A is 1.2 to 5.0, the elongation recovery rate of the long-fiber nonwoven fabric is 50% to 99%, and the apparent density is 0.02 g/cm ³ to 0.20 g/cm ³ .

[2] The long-fiber nonwoven fabric according to the above [1], wherein the long-fiber nonwoven fabric has a maximum breaking elongation E _max (%) of 120% or more and 400% or less.

[3] The long-fiber nonwoven fabric according to the above [2], wherein the ratio E _max /E _min of the maximum breaking elongation E _max (%) to the minimum breaking elongation E _min (%) is 1.5 or more and 5.0 or less.

[4] The long-fiber nonwoven fabric according to any one of [1] to [3] above, wherein the fibers F _A have a crimp number per 25 mm of 0 to 49.

[5] The long-fiber nonwoven fabric according to any one of [1] to [4] above, in which 90.1% by mass or more and 100.0% by mass or less of the thermoplastic resin A is a polyolefin-based polymer and/or a copolymer thereof.

[6] The long-fiber nonwoven fabric according to any one of [1] to [5] above, further comprising at least one long-fiber nonwoven fabric layer composed of fibers F _B mainly composed of a thermoplastic resin B different from the thermoplastic resin A.

[7] The long-fiber nonwoven fabric according to [6], in which 90.1% by mass or more and 100.0% by mass or less of thermoplastic resin B is one or more types selected from the group consisting of polyolefin-based elastomers and polyurethane-based elastomers.

[8] The long-fiber nonwoven fabric according to [6] or [7], wherein the absolute value of the difference between the softening temperature T _{S, A} (°C) of the thermoplastic resin A and the softening temperature T S,B (°C) of the thermoplastic resin B, |T _S,A -T _S,B |, is 10°C or more and 100°C or less.

[9] The long-fiber nonwoven fabric according to any one of [6] to [8], wherein the fibers F _B contain a fatty acid amide compound and the content thereof is 0.01% by mass or more and 5.0% by mass or less.

[10] A sanitary material, at least in part, composed of the long-fiber nonwoven fabric described in any one of [1] to [9] above.

[11] A sanitary material, at least a portion of which is composed of an extensible member in which the long-fiber nonwoven fabric described in any one of [1] to [9] above and a pleated long-fiber nonwoven fabric are bonded together.

[12] A step of forming a laminated sheet having a layer that is composed of fibers F _A having the thermoplastic resin A as a main component;
a step of pressing the laminated sheet with a roll having a surface temperature of 0° C. or more and 120° C. or less to form a fused sheet;
The method for producing a long-fiber nonwoven fabric according to any one of the above [1] to [9], further comprising a step of stretching the fused sheet in the width direction and/or the longitudinal direction at a stretch ratio of 1.5 to 5.0 times.

[13] The method for producing a long-fiber nonwoven fabric according to the above [12], wherein in the step of forming the laminated sheet, the sheet is a laminated sheet further having at least one long-fiber nonwoven fabric layer composed of fibers F _B mainly composed of a thermoplastic resin B different from the thermoplastic resin A.

[14] The method for producing a long-fiber nonwoven fabric according to [12] or [13], wherein in the step of forming the fused sheet, the linear pressure of the roll is 0.5 N/cm or more and 5.0 N/cm or less.

The present invention provides a long-fiber nonwoven fabric that has a smooth surface without pleats and good elasticity. In particular, the long-fiber nonwoven fabric of the present invention has the characteristics of uniform stress during expansion and contraction within the plane, and is thin due to the absence of pleats, so it is expected to be comfortable to wear and unnoticeable, and can be suitably used for sanitary materials such as disposable diapers and sanitary napkins, surgical gowns and drapes, protective clothing, masks, medical tapes, face masks, etc.

FIG. 1 is a diagram illustrating a method for measuring the number of crimps of the long-fiber nonwoven fabric of the present invention. FIG. 2 is a diagram illustrating a method for measuring the apparent maximum fiber diameter D _max (μm) and the apparent minimum fiber diameter D _min (μm) of the long-fiber nonwoven fabric of the present invention.

The long-fiber nonwoven fabric of the present invention is a long-fiber nonwoven fabric having at least one surface constituted by fibers F _A mainly composed of thermoplastic resin A, the ratio D _max /D _min of the apparent maximum fiber diameter D _max (μm) to the apparent minimum fiber diameter D _min (μm) of the fibers _{F A} being 1.2 to 5.0, the elongation recovery rate of the long-fiber nonwoven fabric being 50% to 99%, and the apparent density being 0.02 g/cm ³ to 0.20 g/cm ^3. The components are described in detail below, but the present invention is not limited to the scope described below as long as it does not deviate from the gist of the invention, and various modifications are possible within the scope of the invention.

[Thermoplastic resin A, fiber F _A ]
First, the long-fiber nonwoven fabric of the present invention has at least one surface composed of fibers F _A mainly composed of thermoplastic resin A. Here, in the present invention, "fibers mainly composed of thermoplastic resin A" refers to the fact that 50 mass % or more of the fibers are made of thermoplastic resin A.

Examples of this thermoplastic resin A include aromatic polyester polymers and copolymers thereof, such as "polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate," aliphatic polyester polymers and copolymers thereof, such as "polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalerate copolymer, polycaprolactone," aliphatic polyamide polymers and copolymers thereof, such as "polyamide 6, polyamide 66, polyamide 610, polyamide 10, polyamide 12, polyamide 6-12," polyolefin polymers and copolymers thereof, such as "polypropylene, polyethylene, polybutene, polymethylpentene," water-insoluble ethylene-vinyl alcohol copolymer polymers containing 25 mol% to 70 mol% ethylene units, polystyrene-based, polydiene-based, chlorine-based, polyolefin-based, polyester-based, polyurethane-based, polyamide-based, and fluorine-based elastomer polymers, and any of these may be selected and used. In particular, thermoplastic resins that are not the last group of elastomeric polymers, i.e., the above-mentioned aromatic polyester polymers and their copolymers, aliphatic polyester polymers and their copolymers, aliphatic polyamide polymers and their copolymers, polyolefin polymers and their copolymers, and ethylene-vinyl alcohol copolymer polymers, are preferred because they tend to give the long-fiber nonwoven fabric a smooth feel rather than a rubber-like feel (easily deformed like rubber, resulting in a sticky tackiness and a stick-slip phenomenon that causes discontinuous friction). In the present invention, "elastomeric polymer" refers to a thermoplastic resin that has rubber elasticity at room temperature.

In particular, in the present invention, it is preferable that 90.1% by mass or more and 100.0% by mass or less of the thermoplastic resin A is a polyolefin-based polymer and/or copolymer. By having 90.1% by mass or more and 100.0% by mass or less of the thermoplastic resin A be a polyolefin-based polymer and/or its copolymer, the touch of the long-fiber nonwoven fabric is less likely to become rubbery as described above, and tends to be smooth to the touch.

As described above, the fiber F _A according to the present invention is mainly composed of the thermoplastic resin A, but preferably, it is composed only of the thermoplastic resin A. In either case, the thermoplastic resin A used may be one type, or may be composed of a plurality of thermoplastic resins A.

The fiber F _A according to the present invention is also preferably a composite fiber, and the composite form is not particularly limited as long as it does not impair the effects of the present invention. That is, it can be appropriately selected from (concentric) sheath-core composite fibers, eccentric sheath-core composite fibers, islands-in-the-sea composite fibers, side-by-side composite fibers, polymer blend composite fibers, and the like.

The fiber F _A of the present invention preferably has a crimp number per 25 mm of 0 to 49. By having the crimp number of 0 or more (including those without crimp), preferably 5 or more, the long-fiber nonwoven fabric has a soft feel and a higher elongation. On the other hand, by having the crimp number of 49 or less, preferably 45 or less, more preferably 40 or less, the long-fiber nonwoven fabric has high dimensional stability.

The number of crimps referred to here refers to a value obtained by measuring and calculating as follows.
(i) Five test pieces measuring 2 cm x 2 cm are randomly cut out from the sample.
(ii) An image of the surface of the long-fiber nonwoven fabric is taken with a scanning electron microscope (SEM, for example, "VHX6000" manufactured by Keyence Corporation) at a magnification such that 10 or more fibers can be observed.
(iii) Using the captured image, one fiber F _A constituting the long-fiber nonwoven fabric is randomly selected, and a tangent line L is drawn between two adjacent peaks as shown in the explanatory diagram of Figure 1. Then, the distance (μm) between two contact points P1 and P2 on this tangent line L is measured.
(iv) Calculate the number of crimps per 25 mm of the fiber F _A using the following formula: (Number of crimps per 25 mm of the fiber F _A ) = 25,000 (μm) / (Distance between the two contact points P1 and P2 (μm))
(v) The same operation is performed on four visual fields from one test piece, and on five test pieces, for a total of 20 fibers, to obtain the arithmetic average of the results, and then round the result to the nearest integer.

In order to set the number of crimps within the above range, for example, the composition, viscosity, and molecular weight distribution of the polymer used as the thermoplastic resin A, the fiber diameter and cross-sectional shape of the fiber F _A , the spinning speed, and the cooling conditions during spinning can be adjusted.

The fiber F _A of the present invention has a ratio D _max /D _min of the apparent maximum fiber diameter D _max (μm) to the apparent minimum fiber diameter D _min (μm) of 1.2 or more and 5.0 or less. The apparent maximum fiber diameter D _max (μm) and the apparent minimum fiber diameter D _min (μm) of the present invention are values measured in the same continuous fiber. Therefore, a large D _max /D _min indicates a large change in fiber diameter in the continuous fiber, and when it is made into a long fiber nonwoven fabric, the fiber diameters are large and small, so that the large fiber diameter part can be caught by the surrounding fibers, and excellent shape stability can be obtained. If such shape stability is not imparted, there is a problem that the surface fibers easily move when touched lightly, forming fiber bundles and resulting in a stiff touch.

For this reason, _Dmax / _Dmin is _preferably 1.4 or more, and more preferably 1.6 or more. When _Dmax / _Dmin is 5.0 or less _, a soft touch is achieved, and _Dmax / _Dmin is preferably 4.5 or less, _and more preferably 4.0 or _less .

As long as the above _Dmax (μm) satisfies the above _Dmax / _Dmin relationship, it is preferred that the Dmax (μm) is 0.5 or more and 50.0 or less. By having the _Dmax (μm) be 0.5 or more, more preferably 1.0 or more, and even more preferably 1.5 or more, high dimensional stability is easily obtained. On the other hand, by having the _Dmax (μm) be 50.0 or less, more preferably 40.0 or less, and more preferably 30.0 or less, a long-fiber nonwoven fabric with high flexibility is obtained.

As long as the above D _max /D _min relationship is satisfied, the D _{min (μm) is preferably 0.4 or more and 40.0 or less. By making the D min (} μm) 0.4 or more, more preferably 0.9 or more, and even more preferably 1.4 or more, a stiff feel is easily obtained. On the other hand, by making the D _min (μm) 40.0 or less, more preferably 30.0 or less, and even more preferably 20.0 or less, a long-fiber nonwoven fabric having a soft feel is obtained.

The above D _max (μm), D _min (μm) and D _max /D _min refer to values obtained by measurement and calculation as follows.
(i) An image of the surface of the long-fiber nonwoven fabric is taken with a scanning electron microscope (SEM, for example, "VHX6000" manufactured by Keyence Corporation) in an area where the fibers F _A can be observed continuously for 1 mm or more.
(ii) Twenty different fibers are randomly selected from the captured image, and for one of them, the apparent maximum fiber diameter _Dmax (μm) and the apparent minimum fiber diameter _Dmin (μm) of fiber F _A in the measurement range are measured. For example, in the example of the explanatory diagram in Figure 2, the points showing the apparent maximum fiber diameter _Dmax (μm) and the apparent minimum fiber diameter _Dmin (μm) are determined at the positions shown in Figure 2, and the distance between these positions is measured. Note that fibers fused together at the fusion portion are not measured.
(iii) This maximum apparent fiber diameter D _max (μm) is divided by the minimum apparent fiber diameter D _min (μm) to determine D _max /D _min for that fiber.
(iv) The same operation is performed on the remaining 19 fibers, and a simple number average is calculated from the results. The values are rounded off to one decimal place to determine D _max (μm), D _min (μm), and D _max /D _min for that long-fiber nonwoven fabric.

In order to set the ratio D _max /D _min within the above range, for example, the melting point or softening temperature of the polymer used as the thermoplastic resin A, the fiber diameter or cross-sectional shape of the fiber F _A , and the shape, temperature, and linear pressure of the embossing roll in the process of forming the fused sheet can be adjusted. Specifically, first, the lower the melting point or softening temperature of the polymer, the greater the D _max /D _min can be. Then, the larger the fiber diameter of the fiber F _A , the easier it is to increase D _max /D _min , and when the fiber cross-sectional shape includes a circular portion and a flat portion, it is easy to increase D _max /D _min . Furthermore, with regard to the shape of the embossing roll, the smaller the area of the protruding portion (convex portion) corresponding to the fused portion, the easier it is to increase D _max /D _min , and the higher the forming temperature and linear pressure in the process of forming the fused sheet, the easier it is to increase D _max /D _min .

[Thermoplastic resin B, fiber F _B ]
The long-fiber nonwoven fabric of the present invention preferably further comprises at least one long-fiber nonwoven fabric layer composed of fibers F 2 _B having a thermoplastic resin B different from the thermoplastic resin A as a main component.

This thermoplastic resin B is different from thermoplastic resin A, and is generally preferably a polymer compound having soft and hard segments, specific examples of which include polyurethane-based elastomers, polypropylene-based elastomers, polyethylene-based elastomers, polyester-based elastomers, polystyrene-based elastomers, and polybutadiene-based elastomers.

The thermoplastic resin B is preferably one or more selected from the group consisting of polyolefin-based elastomers and polyurethane-based elastomers, with 90.1% by mass or more and 100.0% by mass or less of the thermoplastic resin B. When a polyolefin-based elastomer is used, the adhesiveness to other long-fiber nonwoven fabric layers and their constituent fibers is good, resulting in a long-fiber nonwoven fabric with excellent shape stability. When a polyurethane-based elastomer is used, the resulting long-fiber nonwoven fabric has excellent elasticity.

In the case where the long-fiber nonwoven fabric of the present invention has at least one long-fiber nonwoven fabric layer composed of fibers F _B mainly composed of a thermoplastic resin B different from thermoplastic resin A, it is preferable that the absolute value |T _S,A -T _S,B | of the difference between the softening temperature T _S,A (°C) of the thermoplastic resin A and the softening temperature T _S,B (°C) of the thermoplastic resin B is 10°C or more and 100°C or less. When the absolute value |T _S,A -T _S,B | is preferably 10°C or more, more preferably 15°C or more, even if fused parts are provided in the long-fiber nonwoven fabric, the fiber shape can be retained in the fused parts, resulting in a long-fiber nonwoven fabric with excellent strength. On the other hand, by making the absolute value |T _S,A -T _S,B | preferably 100°C or less, more preferably 80°C or less, when the fibers F _A are partially compressed and deformed in, for example, the process of forming a fused sheet described below, only the fibers F _B are fused, and the fibers F _A are easily in a state of being in close contact but not fused together (provided that T _S,A >T _S,B in the above). This makes it easy to separate the closely-contacted fibers F _A into individual fibers in the subsequent process of stretching the fused sheet. As a result, it becomes easier to increase the ratio D _max /D _min , and a long-fiber nonwoven fabric having shape stability, high elongation, and softness is obtained.

In the present invention, the softening temperature T _S,A (°C) of the thermoplastic resin A and the softening temperature T _S,B (°C) of the thermoplastic resin B refer to values measured and calculated by the following method.
(i) Ten fibers each of fibers F _A and F _B , each 2 mm or larger, are randomly cut out from the non-fused portion of the sample.
(ii) Using a nano-thermal analyzer device (e.g., "Nano-TA2" manufactured by Anasys Instruments) in which a temperature sensor that also serves as a heater is attached to the probe (cantilever) of an atomic force microscope (AFM), the softening temperature is measured by increasing the temperature at a heating rate of 10°C/sec.
(iii) The same operation is performed on 10 different fibers, and the arithmetic mean value (°C) of the results is calculated, and the value is rounded off to the first decimal place.

Furthermore, in the long fiber nonwoven fabric of the present invention, it is preferable that the fibers F _B contain a fatty acid amide compound. In this case, the content of the fatty acid amide is preferably 0.01% by mass or more and 5.0% by mass or less. When the fibers F _B contain 0.01% by mass or more of a fatty acid amide compound, the slipperiness and flexibility are improved. Furthermore, when the fibers F _B contain 5.0% by mass or less of a fatty acid amide compound, a non-slip feel is obtained. More preferably, the fatty acid amide compound is contained in an amount of 0.05% by mass or more. It is more preferable that the upper limit of the fatty acid amide compound is 1.0% by mass.

The fatty acid amide compounds include saturated fatty acid monoamide compounds, saturated fatty acid diamide compounds, unsaturated fatty acid monoamide compounds, and unsaturated fatty acid diamide compounds.

The number of carbon atoms in the fatty acid amide compound is preferably 15 or more and 50 or less. In the present invention, the number of carbon atoms means the number of carbon atoms contained in the molecule, and includes the number of carbon atoms contained in amide groups, etc. Examples of the fatty acid amide compound having 15 to 50 carbon atoms include palmitic acid amide, palmitoleic acid amide, stearic acid amide, oleic acid amide, elaidic acid amide, vaccenic acid amide, linoleic acid amide, linolenic acid amide, pinolenic acid amide, eleostearic acid amide, stearidonic acid amide, bosseopentaenoic acid amide, arachidic acid amide, gadoleic acid amide, eicosenoic acid amide, eicosadienoic acid amide, mead acid amide, eicosatrienoic acid amide, arachidonic acid amide, eicosatetraenoic acid amide, eicosapentaenoic acid amide, heneicosyl acid amide, behenic acid amide, erucic acid amide, docosadienoic acid amide, adrenic acid amide, osbondoic acid amide, sardine acid amide, docosahexaenoic acid amide, Examples of the fatty acid amide include lignoceric acid amide, nervonic acid amide, tetracosapentaenoic acid amide, nisinic acid amide, cerotic acid amide, montanic acid amide, melissic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, methylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bisoleic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, ethylene biserucic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, distearyl adipic acid amide, distearyl sebacic acid amide, and hexamethylene bisoleic acid amide, and a combination of these may be used. The number of carbon atoms of the fatty acid amide compound is preferably 15 or more, more preferably 23 or more, and even more preferably 30 or more, to provide a long-fiber nonwoven fabric that is not sticky. On the other hand, by having a carbon number of the fatty acid amide compound of preferably 50 or less, more preferably 45 or less, and even more preferably 42 or less, the fatty acid amide compound is appropriately precipitated on the fiber surface, resulting in a long-fiber nonwoven fabric with excellent flexibility.

The average single fiber diameter (μm) of the long-fiber nonwoven fabric layer composed of the fibers F 1 _B is preferably 0.5 μm or more and 50.0 μm or less. When this average single fiber diameter is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.5 μm or more, the long-fiber nonwoven fabric has high breathability. On the other hand, when the average single fiber diameter is preferably 50.0 μm or less, more preferably 40.0 μm or less, and more preferably 30.0 μm or less, the long-fiber nonwoven fabric has high elongation.

The basis weight (g/ ^m2 ) of the long-fiber nonwoven fabric layer composed of the fibers F _B is preferably 5 g/m2 or ^more and 200 g/ ^m2 or less. When this basis weight is preferably 5 g/m2 or ^more , more preferably 10 g/m2 ^{or more} , the long-fiber nonwoven fabric has a high elongation recovery rate. On the other hand, when the basis weight is preferably 200 g/m2 ^or less, more preferably 100 g/m2 or ^less , and even more preferably 50 g/m2 ^or less, the flexibility is high.

[Long fiber nonwoven fabric]
The long-fiber nonwoven fabric of the present invention has at least one surface made of fibers F _A mainly composed of thermoplastic resin A. The long-fiber nonwoven fabric of the present invention has an elongation recovery rate of 50% or more and 99% or less, and an apparent density of 0.02 g/cm ³ or more and 0.20 g/cm ³ or less. By satisfying these two requirements, the long-fiber nonwoven fabric has good stretchability. The long-fiber nonwoven fabric of the present invention refers not only to a single layer made of fibers F _A mainly composed of thermoplastic resin A (sometimes referred to as O layer), but also to a layer made of a long-fiber nonwoven fabric layer (sometimes referred to as I layer) made of fibers F _B mainly composed of thermoplastic resin B different from thermoplastic resin A on one surface side and a layer made of O layer on the other surface side, a layer made of O layer on both surface sides, and a layer made of O layer/I layer/O layer in this order, and also to a layer made of multiple long-fiber nonwoven fabric layers. In addition, other structures such as fiber layers may be included within the scope of not impairing the effects of the present invention. When a nonwoven fabric is used as the structure other than the nonwoven fabric to be laminated on the long-fiber nonwoven fabric of the present invention, examples of the nonwoven fabric include nonwoven fabrics obtained by known manufacturing methods such as the spunbond method, meltblowing method, and short fiber carding method. In addition, the resin constituting the structure other than the nonwoven fabric of the present invention is not particularly limited, but it is preferably composed of polypropylene because it is easy to bond.

Here, the layer (O layer) made of fibers F _A mainly composed of thermoplastic resin A is specifically a nonwoven fabric layer made of fibers F _A mainly composed of thermoplastic resin A, and more specifically, this nonwoven fabric layer is a spunbond nonwoven fabric layer or a meltblown nonwoven fabric layer formed by a method described later. In particular, a spunbond nonwoven fabric layer is more preferable.

The long-fiber nonwoven fabric layer (I layer) made of fibers F 3 B mainly composed of thermoplastic resin B different from thermoplastic resin A is a long-fiber nonwoven fabric layer made of fibers F 3 _B mainly composed of thermoplastic resin B different from thermoplastic resin _A , and more specifically, this long-fiber nonwoven fabric layer is a spunbond nonwoven fabric layer or a meltblown nonwoven fabric layer formed by a method described later. It is more preferable that this layer is a spunbond nonwoven fabric layer.

First, the long-fiber nonwoven fabric of the present invention has a stretch recovery rate of 50% or more and 99% or less. By having this stretch recovery rate of 50% or more, preferably 60% or more, and more preferably 70% or more, the long-fiber nonwoven fabric will provide a comfortable fit when used as a material for wearable items such as sanitary materials like disposable diapers. On the other hand, the higher the stretch recovery rate, the better, but in reality, the long-fiber nonwoven fabric will have a stretch recovery rate of 99% or less.

In the present invention, the stretch recovery rate of the long-fiber nonwoven fabric refers to a value measured and calculated by the following method.
(i) Five test pieces are randomly cut out from the sample in the same direction as the direction showing the maximum breaking elongation measured and calculated by the method described below.
(ii) Using a tensile tester (for example, "TENSILON""UCT-100" manufactured by Orientec Co., Ltd.), the test piece is pulled at a pulling speed of 200 mm/min until the elongation of the test piece reaches 100%, and then allowed to stand for 1 minute.
(iii) Thereafter, when returning to the original position at a speed of 200 mm/min, the elongation percentage (%) at which the stress becomes 0 N is measured.
(iv) Next, the elongation percentage (%) is subtracted from 100% to obtain a value (%). The same operation is carried out for a total of five test pieces, and the arithmetic average value is calculated and rounded off to the first decimal place.

In order to set the elongation recovery rate within the above range, for example, the composition and viscosity of the polymers used as the thermoplastic resin A and the thermoplastic resin B, the fiber diameter and cross-sectional shape of the fibers F _A and F _B , the spinning speed, the cooling conditions during spinning, and the apparent density of the long-fiber nonwoven fabric can be adjusted.

The long-fiber nonwoven fabric of the present invention has an apparent density of 0.02 g/cm3 ^or more and 0.20 g/cm3 ^or less. When the apparent density is 0.20 g/cm3 or ^less , more preferably 0.18 g/cm3 or ^less , and even more preferably 0.16 g/cm3 or ^less , the long-fiber nonwoven fabric has excellent breathability and softness and a high sense of bulk. On the other hand, when the apparent density is 0.02 g/cm3 or ^more , preferably 0.04 g/cm3 or ^more , and more preferably 0.06 g/cm3 or ^more , the long-fiber nonwoven fabric has excellent shape stability.

In the present invention, the apparent density of the long-fiber nonwoven fabric refers to a value calculated by the following formula: apparent density (g/cm ³ )=basis weight (g/m ² )/thickness (mm)/1000.
Here, the basis weight refers to the mass per m2 (g/m2) calculated based on "6.2 Mass per unit area" of JIS L1913:2010 "Testing methods for general nonwoven fabrics" by randomly taking three 20 cm x ^{25 cm} test pieces per 1 m of sample width, measuring the mass (g) of each piece under standard conditions, and averaging the measured masses. The thickness refers to the no-load thickness measured using a shape measuring machine (for example, "VR3050" manufactured by Keyence Corporation) in an area of 5 mm x 5 mm or more.

Furthermore, the long-fiber nonwoven fabric of the present invention preferably has a maximum breaking elongation of 120% or more and 400% or less. By having a maximum breaking elongation of preferably 120% or more, more preferably 150% or more, the long-fiber nonwoven fabric becomes easy to stretch when used as a material for wearable items such as sanitary materials like disposable diapers. On the other hand, by having the maximum breaking elongation of preferably 400% or less, more preferably 300% or less, the long-fiber nonwoven fabric becomes one that stops stretching at an appropriate position when used as a material for wearable items such as sanitary materials like disposable diapers.

Furthermore, the long-fiber nonwoven fabric of the present invention preferably has a ratio E _max /E _min of the maximum breaking elongation E _max (%) to the minimum breaking elongation E _min (%) of 1.5 to 5.0. When the ratio E _max /E _min of the maximum breaking elongation E _max (%) to the minimum breaking elongation E _min (%) is 1.5 or more, preferably 1.6 or more, the long-fiber nonwoven fabric becomes easy to wear when used as a material for wearable items such as sanitary materials such as disposable diapers. On the other hand, when the ratio E _max /E _min is 5.0 or less, preferably 4.0 or less, the long-fiber nonwoven fabric has a soft feel.

In the long-fiber nonwoven fabric of the present invention, the maximum breaking elongation E _max (%), the minimum breaking elongation E _min (%), and the ratio E _max /E _min of the maximum breaking elongation E _max (%) to the minimum breaking elongation E _min (%) refer to values measured and calculated by the following methods.
(i) One arbitrary direction of the sample is defined as 0 degrees, and five test pieces are randomly cut out from the sample.
(ii) Using a tensile tester (for example, "TENSILON""UCT-100" manufactured by Orientec Co., Ltd.), measure the elongation at which the test piece breaks (breaking elongation) at a tensile speed of 200 mm/min. This operation is carried out for all five test pieces, and the arithmetic average value is calculated and rounded off to the first decimal place, and this is regarded as the breaking elongation at 0 degrees.
(iii) A similar operation is performed in five directions (30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees) in increments of 30 degrees from the 0 degree direction.
(iv) Of the obtained breaking elongations at each angle, the breaking elongation in the direction showing the largest value is designated as the maximum breaking elongation E _max (%), and the breaking elongation in the direction showing the smallest value is designated as the minimum breaking elongation E _min (%).
(v) Furthermore, the ratio E _max /E _min is rounded off to one decimal place.

In order to set the maximum breaking elongation _Emax within the above range, for example, means may be used to adjust the composition, viscosity, molecular weight distribution, fiber diameter and cross-sectional shape of fiber F _A , spinning speed, and cooling conditions during spinning of the polymer used as thermoplastic resin A, the composition, viscosity, fiber diameter and cross-sectional shape of fiber F _B , spinning speed, and cooling conditions during spinning of the polymer used as thermoplastic resin B, and the apparent density of the long-fiber nonwoven fabric. In order to set the ratio _Emax / _Emin of the maximum breaking elongation _Emax to the minimum breaking elongation _Emin within the above range, for example, means may be used to adjust the orientation direction of fiber F _A , the orientation direction and degree of crimp of fiber F _B , and the mass ratio of fiber F _A to fiber F _B.

[Method of manufacturing long fiber nonwoven fabric]
A preferred embodiment of the method for producing the long-fiber nonwoven fabric of the present invention is as follows:
(a) forming a laminated sheet having a layer that is to be a layer composed of fibers F _A having the thermoplastic resin A as a main component;
(b) pressing the laminated sheet with a roll having a surface temperature of 0° C. or more and 120° C. or less to form a fused sheet;
(c) further stretching the fused sheet by 1.5 to 5.0 times;
It includes.

The following provides a more detailed explanation of each of the above steps.

(a) Step of forming a laminated sheet First, in this step, a sheet is formed having a layer that will become a layer composed of fibers F _A whose main component is the thermoplastic resin A. As described above, the layer that will become a layer composed of fibers F _A whose main component is thermoplastic resin A is preferably a nonwoven fabric layer formed by the spunbond method or the meltblowing method, and more preferably a nonwoven fabric layer formed by the spunbond method.

The spunbond method is a method of manufacturing nonwoven fabric that generally involves melting the thermoplastic resin raw material, spinning it from a spinneret, pulling it with high-speed air to obtain threads, collecting them on a moving collection belt to form a nonwoven fiber web, and then thermally bonding it. By using the spunbond method in the long-fiber nonwoven fabric of the present invention, molecular orientation is promoted by the pulling with high-speed air, and the fibers are firmly fixed together by thermal bonding, so that it can obtain sufficient strength for use as a sanitary material, etc.

A spinneret used for forming a layer composed of fibers F _A mainly composed of thermoplastic resin A according to the present invention may have a round hole or a different shape hole as appropriate, but from the viewpoint of spinning stability, a round hole is preferred. In particular, it is a preferred embodiment to perform composite spinning in order to increase the number of crimps, and in this case, a spinneret equipped with a mechanism capable of forming a side-by-side type composite cross section or an eccentric core-sheath composite cross section may be used.

The spinning speed, which is the speed finally reached by pulling with high-speed air when forming a layer composed of fibers F _A mainly composed of thermoplastic resin A according to the present invention, is preferably 2000 m/min or more, more preferably 3000 m/min or more. By setting the spinning speed to 2000 m/min or more, high productivity is achieved, and the orientation and crystallization of the fibers progresses, making it possible to obtain fibers with higher strength and long-fiber nonwoven fabrics with higher strength. On the other hand, the spinning speed is preferably 8000 m/min or less, more preferably 7000 m/min or less. In this way, a long-fiber nonwoven fabric with excellent flexibility can be obtained.

In this step, the sheet is preferably a laminated sheet further having at least one layer serving as a long-fiber nonwoven fabric layer composed of fibers F _B mainly composed of a thermoplastic resin B different from the thermoplastic resin A. The thermoplastic resin B here is the thermoplastic resin B. In particular, adding 0.01% by mass or more and 5.0% by mass or less of the fatty acid amide compound to the thermoplastic resin B and spinning the mixture is more preferable from the viewpoint of smooth fiberization in the spinning step and stabilizing the process.

As described above, the long-fiber nonwoven fabric layer composed of fibers F _B mainly composed of thermoplastic resin B different from thermoplastic resin A is preferably a nonwoven fabric layer formed by a spunbond method or a meltblowing method, and more preferably a nonwoven fabric layer formed by a spunbond method.

In this step, as described above, a sheet having a layer that will become a layer composed of fibers F _{2 A} whose main component is thermoplastic resin A is formed. In the case where the long-fiber nonwoven fabric is only a layer composed of fibers F 2 _A whose main component is thermoplastic resin A, this layer is formed and then the next step is carried out as is. In the case where layers (other layers) other than the layer composed of fibers F 2 _A whose main component is thermoplastic resin A are included, a laminated sheet is formed by laminating layers that will become the other layers, and then the next step is carried out. Examples of the other layers include a layer that will become a long-fiber nonwoven fabric layer composed of fibers F 2 _B whose main component is thermoplastic resin B different from thermoplastic resin A, and a layer that will become the other structure. Among them, it is preferable to laminate a layer that will become a long-fiber nonwoven fabric layer composed of fibers F 2 _B whose main component is thermoplastic resin B different from thermoplastic resin A. In the case where the other layers are laminated, at least one of these layers can be laminated. In the subsequent steps and thereafter, when the long-fiber nonwoven fabric has only a layer composed of fibers F _A having thermoplastic resin A as a main component, the term "laminate sheet" should be read as "a layer which will be composed of fibers F _A having thermoplastic resin A as a main component."

The laminated sheet is selected depending on the purpose of use, and as described above, when it becomes a long-fiber nonwoven fabric, it has the following configuration, that is, a layer (O layer) composed of fibers F _A whose main component is thermoplastic resin A on one surface side and a long-fiber nonwoven fabric layer (I layer) composed of fibers F _B whose main component is thermoplastic resin B different from thermoplastic resin A on the other surface side, a layer having O layers laminated on both surface sides, and further a layer having O layers/I layers/O layers laminated in this order, which includes a plurality of long-fiber nonwoven fabric layers. Specific laminated structures of four or more layers not mentioned above include, for example, O layers/I layers/I layers/O layers, O layers/I layers/O layers/I layers, O layers/I layers/O layers/I layers/O layers, and O layers/I layers/I layers/I layers/O layers. Among these, a form in which a layer made of fiber F _A , which is likely to provide a smooth touch, is laminated on both sides of a layer made of fiber F _B, which is likely to provide a rubber-like touch, i.e., a form in which the layers are laminated in the order of O layer/I layer/O layer, or a form in which the layers are laminated in the order of O layer/I layer/O layer/I layer/O layer, is more preferable.

In the present invention, it is preferable that the layers of the laminated sheet are integrated. Integrating here means that these layers are joined by entangling the fibers, fixing with an adhesive or other component, or fusing the thermoplastic resins that make up each layer together. However, when joining by fusing the thermoplastic resins that make up each layer together, this may be done simultaneously with step (b) described below, and it is also preferable to join them by, for example, forming the I layer directly on the O layer.

(b) Step of Forming a Fused Sheet Next, in this step, the sheet is pressed with a roll having a surface temperature of 0° C. or more and 120° C. or less to form a fused sheet.

The rolls used in this process are preferably ones that give the laminated sheet a regular pattern of fused parts, and more specifically, it is more preferable for them to be a pair of rolls consisting of an embossing roll and a flat roll that have a regular pattern.

Here, the embossing roll having a regular pattern is, for example, one having protrusions (convex portions) formed in the portions corresponding to the fused parts, or one having concave shapes formed in the portions not corresponding to the fused parts. In particular, if the top portions of the convex portions corresponding to the fused parts are further uneven or have curved top surfaces, the flattened fibers F _A can be more easily separated from each other in the step of stretching the fused sheet described below.

The fused portions are preferably provided so that the distance between adjacent fused portions is 50 μm or more and 20 mm or less. By making the distance between fused portions 50 μm or more, a long-fiber nonwoven fabric having flexibility and excellent stretchability can be produced. On the other hand, by making the distance between fused portions 20 mm or less, the shape stabilization effect of the flattened portion formed by the pressurizing portion can be easily obtained.

Furthermore, the surface temperature of the roll is preferably 0° C. or higher and 120° C. or lower. By setting the surface temperature at 0° C. or higher, more preferably 5° C. or higher, and even more preferably 10° C. or higher, a long-fiber nonwoven fabric having excellent dimensional stability can be obtained, and the fibers F _A in the pressurizing section can be further flattened to increase the apparent fiber diameter. On the other hand, by setting the surface temperature at 120° C. or lower, more preferably 90° C. or lower, and even more preferably 60° C. or lower, the flattened fibers F _A can be more easily separated from each other in the step of stretching the fused sheet described below.

In addition, it is preferable that the linear pressure of the roll be 0.5 N/cm or more and 5.0 N/cm or less for the above-mentioned pressing. By pressing with such a linear pressure to form a fused sheet, the adhesion between the fibers can be easily released in the process of stretching the fused sheet described below.

(c) Step of Stretching the Fused Sheet In this step, the fused sheet is stretched in the width direction and/or the longitudinal direction in the range of 1.5 to 5.0 times. This stretching may be performed by a general stretching device that stretches the fused sheet in the width direction and/or the longitudinal direction, or a method called gear stretching described in JP-A-2003-73967 may be used. In any case, by going through this step, the "layer that will become a layer composed of fibers F _A having thermoplastic resin A as a main component" becomes a "layer composed of fibers F _A having thermoplastic resin A as a main component".

By setting the lower limit of the above range (sometimes referred to as the stretch ratio) to preferably 1.5 times or more, more preferably 2.0 times or more, the adhesion between the fibers F _A in the fused parts can be released, and a long-fiber nonwoven fabric with excellent elasticity can be obtained. In addition, the release of the adhesion increases the thickness and the bulk, and a long-fiber nonwoven fabric with a soft touch can be obtained. On the other hand, by setting the above range (stretch ratio) to preferably 5.0 times or less, more preferably 4.0 times or less, the adhesion between the fibers F _A can be partially maintained, and a long-fiber nonwoven fabric with excellent shape stability can be obtained.

The roll temperature (stretching temperature) of the gear roll during stretching in the present invention is preferably 10°C or higher and 150°C or lower. By setting the stretching temperature to preferably 10°C or higher, more preferably 30°C or higher, and even more preferably 50°C or higher, the fibers can be stretched without breaking. On the other hand, by setting the stretching temperature to preferably 150°C or lower, more preferably 130°C or lower, deformation of the fibers during the process can be reduced, allowing for stable stretching.

This step may be carried out immediately (continuously) after the fused sheet is obtained, or it may be carried out after the fused sheet is first wound into a roll and then sent out.

(4) Other Steps Depending on the application or purpose, the long-fiber nonwoven fabric of the present invention may be appropriately subjected to processes such as drilling holes, applying various treatments such as hydrophilic treatment, laminating with other materials, printing, etc.

The perforation process may be performed to create openings that penetrate through the thickness direction, or to create blind holes that are only open in specific layers.

The application of the treatment agent may include a squeezing or drying process, if necessary. The method for applying the treatment agent to the long-fiber nonwoven fabric is not particularly limited, and examples include a method of applying a liquid in which the treatment agent is dissolved or dispersed, and a method of immersion. In addition to hydrophilic agents, examples of treatment agents include antibacterial agents, antioxidants, preservatives, matting agents, pigments, rust inhibitors, fragrances, and defoamers.

In addition, when laminating the other structures to the long-fiber nonwoven fabric of the present invention, the method of laminating (e.g., bonding) each layer is not limited. For example, it can be performed by a known method such as heat fusion such as heat embossing or ultrasonic fusion, mechanical entanglement such as needle punching or water jet, or adhesion with a hot melt or solvent-based adhesive.

Printing methods include known methods such as gravure printing, mold printing, silk screen printing, and offset printing.

[Hygienic materials]
The sanitary material of the present invention is preferably at least partially composed of the long-fiber nonwoven fabric. By using such a long-fiber nonwoven fabric as an extensible material, the sanitary material has excellent touch and stretchability.

Furthermore, it is also preferable that at least a portion of the sanitary material of the present invention is composed of an extensible member in which the long-fiber nonwoven fabric and the pleated long-fiber nonwoven fabric are bonded together, as this provides excellent surface durability.

The sanitary materials of the present invention refer to primarily disposable items used for health-related purposes such as medical care and nursing care, and specific examples include disposable diapers, sanitary napkins, gauze, bandages, masks, gloves, bandages, etc., as well as their constituent parts, such as the top sheet, back sheet, and side gathers of disposable diapers.

Next, the present invention will be specifically explained based on examples. However, the present invention is not limited to these examples.

[Measurement method]
The evaluation methods and measurement conditions used in the examples are described below. In addition, in the measurement of each physical property, unless otherwise specified, the measurement and calculation were performed based on the above-mentioned methods.

(1) Softening temperature T _S,A (°C) of thermoplastic resin A, softening temperature T _S,B (°C) of thermoplastic resin B, and absolute value of the difference between them |T _S,A -T _S,B | (°C)
The nano-thermal analyzer device, "Nano-TA2" manufactured by Anasys Instruments, was used as a nano-thermal analyzer device having a temperature sensor that also serves as a heater attached to the probe (cantilever) of an atomic force microscope (AFM), and measurements and calculations were performed using the above-mentioned method.

(2) Average single fiber diameter (μm) of fibers F _A and F _B before the process of forming a fused sheet
The average single fiber diameter (μm) before the step of forming a fused sheet was measured by the following procedure.
(i) Each layer was formed independently, and ten test pieces of 5 mm x 5 mm were randomly cut out from each of the layers excluding a 10 cm area from each end in the width direction.
(ii) The test piece was embedded in an embedding agent such as epoxy resin, and an image of the fiber cross section perpendicular to the fiber axis was taken using a scanning electron microscope "SU1510" manufactured by Hitachi High-Technologies Corporation at a magnification such that 10 or more fibers could be observed.
(iii) Fibers randomly extracted from each captured image were analyzed using image analysis software ImageJ to measure the cross-sectional area of each fiber, and the single fiber diameter (μm) of the fiber calculated as a perfect circle was calculated.
(iv) Ten measurements were made for each test piece, and the arithmetic mean value (μm) was rounded off to one decimal place to obtain the average single fiber diameter (μm) of the fibers.

(3) Spinnability (grade) of the layer (O layer) composed of fiber F _A and the layer (I layer) composed of fiber F _B
The number of times each layer was broken during spinning was counted and evaluated according to the following classification.
5: No yarn breakage occurred during 10 minutes of spinning.
3: The number of yarn breakages was 1 to 9 times within 10 minutes during spinning.
1: The number of yarn breakages was 10 or more times within 10 minutes during spinning.

(4) The basis weight (g/m ² ) of the layer (O layer) composed of the fiber F _A and the layer (I layer) composed of the fiber F _B
The basis weight of each layer was determined by forming each layer independently, randomly taking three 20 cm x 25 cm test pieces per meter of sample width from each layer, measuring the mass (g) of each piece under standard conditions, and calculating the mass per ^m2 (g/ ^m2 ) from the average value.

(5) Number of crimps per 25 mm of fiber F _A : The number of crimps per 25 mm was measured and calculated using a scanning electron microscope (SEM) "VHX6000" manufactured by Keyence Corporation according to the method described above.

(6) Apparent maximum fiber diameter D _max (μm), apparent minimum fiber diameter D _min (μm), and ratio thereof D _max /D _min (-) of fiber F _A
As a scanning electron microscope (SEM), a "VHX6000" manufactured by Keyence Corporation was used, and measurements and calculations were carried out according to the above-mentioned methods.

(7) Elongation recovery rate (%) of long fiber nonwoven fabric
The tensile strength was measured and calculated by the above-mentioned method using a tensile tester "TENSILON" (UCT-100) manufactured by Orientec Co., Ltd.

(8) Weight (g/ ^m2 ), thickness (mm), and apparent density (g/ ^cm3 ) of long fiber nonwoven fabric
The shape measuring machine used was a "VR3050" manufactured by Keyence Corporation, and measurements and calculations were performed according to the above-mentioned method.

(9) Maximum breaking elongation E _max (%), minimum breaking elongation E _min (%), and ratio thereof E _max /E _min (-) of long fiber nonwoven fabric
The tensile strength was measured and calculated by the above-mentioned method using a tensile tester "TENSILON" (UCT-100) manufactured by Orientec Co., Ltd.

(10) Texture (grade)
The long-fiber nonwoven fabrics were touched by healthy adults (a total of 30 people, 15 men and 15 women) and the surface texture was evaluated using the following three-level scale. The average score of the evaluation results was calculated and used as the evaluation result of the texture of the long-fiber nonwoven fabric.
5: Soft pressing feel including air layer, smooth stroking feel 3: Soft pressing feel including air layer but not smooth, or not soft pressing feel including air layer but smooth stroking feel 1: Neither soft pressing feel including air layer nor smooth stroking feel (hard, rubbery touch).

(11) Shape stability (grade)
The appearance of the long-fiber nonwoven fabric after the evaluation of the above-mentioned (10) skin feel was visually evaluated on a three-level scale according to the following criteria. The evaluation results were then averaged, and the average value was used to evaluate the morphology of the long-fiber nonwoven fabric. The results were used as an evaluation of stability.
5: It is not possible to clearly see any pilling, fuzzing, or twisted fibers.
3: Pilling, fuzzing, and twisted fibers are clearly visible.
1: Peeling of the fiber layer is clearly observed.

[Example 1]
(Layer that will be composed of fibers F _A )
Polypropylene (HP5038 (manufactured by Polymiley), indicated as PP1 in Tables 1 to 8) was melted in an extruder and spun at a spinning temperature of 235°C from a rectangular die with a hole diameter φ of 0.30 mm at a single hole throughput of 0.6 g/min. The spun yarn was pulled at a spinning speed of 3,530 m/min using high-speed air and collected on a moving net to obtain a fiber web, which is a nonwoven fabric layer formed by a spunbond method with a basis weight of 10 g/ ^m2 . The characteristics of the crimped fibers constituting the obtained spunbond nonwoven fabric layer (the layer that will become the layer composed of fibers F _A ) were that the average single fiber diameter was 15.5 μm.

(Layer composed of fiber F _B )
A polypropylene-based elastomer containing 0.2% by mass of fatty acid amide (erucic acid amide) ("Vistamaxx (registered trademark)" 7050 (manufactured by ExxonMobil), represented as TPO1 in Tables 1 to 3) (softening temperature 45°C) was melted in an extruder and spun from a rectangular die at a spinning temperature of 230°C and a throughput of 0.2 g/min per hole. The spun yarn was pulled at a spinning speed of 900 m/min using high-speed air and collected on a moving net to obtain a fiber web, which is a nonwoven fabric layer formed by a spunbond method and has a basis weight of 20 g/ ^m2 . The characteristics of the fibers constituting the obtained spunbond nonwoven fabric layer (layer composed of fibers F _B ) were that the average single fiber diameter was 18.0 μm.

(long fiber nonwoven fabric)
A layer composed of fiber F B was directly collected on top of the layer composed of fiber F _A obtained above, by the method described above, and a nonwoven fabric layer similar to the layer composed of _{fiber F A was} further collected on top of that, thereby forming a laminated sheet.

Then, the obtained laminated sheet was pressed using a metal embossing roll with circular protrusions arranged in a staggered pattern at the same pitch in both the MD and CD directions as the upper roll, and an embossing roll with a pair of upper and lower heating mechanisms consisting of a metal flat roll as the lower roll, at a linear pressure of 3 N/cm and a surface temperature of the embossing roll of 40°C to form a fused sheet.

The fused sheet was then passed through a gear stretching device and stretched 2.4 times in the width direction and 1.1 times in the longitudinal direction at a stretching temperature of 40° C. to obtain a long-fiber nonwoven fabric having a basis weight of 40 g/ ^m2 . The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 1. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 2]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that the fibers constituting the layer (which will become the layer constituted by fiber F _A ) were changed to side-by-side type composite fibers (the resin type is indicated as "PP1-coPE/PP" in Tables 1 to 8) by melting polypropylene (PP1) and ethylene copolymer polypropylene (RP361S (manufactured by Lyondell Basell), coPE/PP) in an extruder at a spinning temperature of 235°C and a mass ratio of 1:1, and spinning them from a rectangular spinneret with a hole diameter of 0.30 mm at a single-hole output rate of 0.6 g/min. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 1. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, a soft feeling of pressing including an air layer, and excellent stretchability.

[Example 3]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that in the layer (composed of fibers F through _B ), a polypropylene-based elastomer was used but was changed to a polyurethane-based elastomer (referred to as TPU in Tables 1 to 8). The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 1. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 4]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that in the layer (made up of fibers F through _B ), a polypropylene-based elastomer having a softening temperature of 45°C was used, but a polypropylene-based elastomer having a softening temperature of 111°C (represented as TPO2 in Table 2) was used instead, and the conditions were as shown in Table 2. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 2. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 5]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that the content of erucic acid amide in (layer composed of fibers F through _B ) was changed from 0.2% by mass to 0.005% by mass. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 2. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 6]
(Layer that will be composed of fibers F _A )
Polypropylene (PP1) and a polypropylene-based elastomer (TPO1) containing 0.1% by mass of fatty acid amide (erucic acid amide) were melted in an extruder, and side-by-side composite fibers (resin type is indicated as "PP1-TPO1" in Table 2) were spun from a rectangular die with a hole diameter of 0.30 mm at a single hole output rate of 0.6 g/min at a spinning temperature of 235°C and a mass ratio of 1:1. The spun yarn was pulled at a spinning speed of 3530 m/min using high-speed air and collected on a moving net to obtain a fiber web, which is a nonwoven fabric layer formed by a spunbond method with a basis weight of 20 g/ ^m2 . The characteristics of the crimped fibers constituting the obtained spunbond nonwoven fabric layer (the layer that becomes the layer composed of fiber F _A ) were an average single fiber diameter of 15.5 μm.

(long fiber nonwoven fabric)
On top of the layer that would become the layer composed of the fibers F _A obtained above, a nonwoven fabric layer similar to the layer composed of the fibers F _A was collected by the method described above.

Then, the obtained laminated sheet was pressed using a metal embossing roll on the upper roll, which has circular protrusions arranged in a staggered pattern at the same pitch in both the MD and CD directions, and an embossing roll on the lower roll, which has a pair of upper and lower heating mechanisms consisting of a metal flat roll, at a linear pressure of 3 N/cm and a surface temperature of the embossing roll of 40°C to form a fused sheet.

The fused sheet was then passed through a gear stretching device and stretched 2.4 times in the width direction and 1.1 times in the longitudinal direction at a stretching temperature of 40° C. to obtain a long-fiber nonwoven fabric having a basis weight of 40 g/ ^m2 . The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 2. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 7]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that the surface temperature of the embossing roll was changed from 40° C. to 55° C., and the linear pressure of the roll was changed from 3 N/cm to 5 N/cm. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 3. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 8]
For the fibers constituting the layer composed of fibers F _A , polyethylene terephthalate (PET) was melted in an extruder, spun from a rectangular spinneret having a hole diameter φ of 0.30 mm at a single-hole throughput rate of 0.9 g/min at a spinning temperature of 290° C., and the spun yarn was pulled at a spinning speed of 4700 m/min using high-speed air, to obtain a long-fiber nonwoven fabric in the same manner as in Example 1. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 3. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and had excellent stretchability.

[Example 9]
For the fibers constituting the layer composed of fibers F _A , polybutylene terephthalate (PBT) was melted in an extruder, spun from a rectangular spinneret having a hole diameter φ of 0.30 mm at a single hole output rate of 0.9 g/min at a spinning temperature of 260° C., and the spun yarn was pulled at a spinning speed of 4700 m/min using high-speed air, to obtain a long-fiber nonwoven fabric in the same manner as in Example 1. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 3. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and had excellent stretchability.

[Example 10]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that for the fibers constituting the layer (fiber F _A ), polyamide 6 (N6) was melted in an extruder, spun at a spinning temperature of 260° C. from a rectangular spinneret with a hole diameter φ of 0.30 mm at a single-hole throughput of 0.9 g/min, and the spun yarn was pulled at a spinning speed of 4700 m/min using high-speed air. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 4. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and had excellent stretchability.

[Example 11]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 2, except that polypropylene (PP1) and polyethylene (PE) were melted in an extruder for the fibers constituting the layer (fiber F _A) . The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 4. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, a soft feel with an air layer, and excellent stretchability.

[Example 12]
For the fibers constituting the layer composed of fibers F _A , polybutylene terephthalate (PBT) and polyethylene (PE) were melted in an extruder, respectively, and spun from a rectangular die having a hole diameter φ of 0.30 mm at a single hole output rate of 0.9 g/min at a spinning temperature of 260° C. and a mass ratio of 1:1, and the spun yarn was pulled at a spinning speed of 4700 m/min using high-speed air (the resin type was indicated as "PBT-PE"). A long-fiber nonwoven fabric was obtained in the same manner as in Example 2, except that the fibers were melted in an extruder and spun from a rectangular die having a hole diameter φ of 0.30 mm at a single hole output rate of 0.9 g/min at a spinning temperature of 260° C. and a mass ratio of 1:1, and the spun yarn was pulled at a spinning speed of 4700 m/min using high-speed air (the resin type was indicated as "PBT-PE"). The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 4. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, a soft feeling of pressing including an air layer, and excellent stretchability.

[Example 13]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 12, except that for the fibers constituting the layer (fiber F _A ), polyethylene terephthalate (PET) and polyethylene (PE) were melted in an extruder and the spinning temperature was 290°C (the resin type was indicated as "PET-PE"). The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 5. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, a soft feel with an air layer, and excellent stretchability.

[Example 14]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that in the layer (composed of fibers F through _B ), a styrene-based elastomer (represented as SEBS in the table) was used instead of the polypropylene-based elastomer used in the layer (composed of fibers F through B). The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 5. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 15]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that in the layer (made up of fibers F through _B ), a polypropylene-based elastomer having a softening temperature of 45°C was used, but a polyethylene-based elastomer having a softening temperature of 95°C (referred to as TPO3 in the table) was used instead. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 5. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 16]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that in the layer (made up of fibers F _B ), a polypropylene-based elastomer (TPO1) and a styrene-based elastomer (SEBS) were mixed in a mass ratio of 95:5 and melted in an extruder (the resin type was indicated as "TPO1-SEBS"). The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 6. The obtained long-fiber nonwoven fabric had a smooth surface without pleats and good stretchability.

[Example 17]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 2, except that for the fibers constituting the layer composed of fibers F _A , polypropylene (PP1) and polypropylene having a higher viscosity (HP562T (manufactured by Lyondell Basell), PP2) were melted in an extruder, respectively. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 6. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, a soft feel with an air layer, and excellent stretchability.

[Comparative Example 1]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that the obtained laminated sheet was not pressed but was passed directly through the gear stretching device (long-fiber nonwoven fabric). The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 7. The obtained long-fiber nonwoven fabric had good stretchability, but the fibers on the surface easily moved when touched lightly, forming fiber bundles that made the fabric stiff to the touch, and the fiber layers partially peeled off, making it difficult to put into practical use.

[Comparative Example 2]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that the surface temperature of the embossing roll was changed from 40° C. to 130° C. and other conditions were changed as shown in Table 7. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 7. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, but the fibers were partially fuzzed and it was poor in stretchability.

[Comparative Example 3]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 2, except that the surface temperature of the embossing roll was changed from 40° C. to 130° C., and other conditions were changed as shown in Table 7. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 7. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, but the fibers were partially fuzzed and it was poor in stretchability.

[Comparative Example 4]
A long-fiber nonwoven fabric was obtained in the same manner as in Example 1, except that the surface temperature of the embossing roll was changed from 40° C. to 55° C., and the linear pressure of the roll was changed from 3 N/cm to 150 N/cm. The evaluation results of the obtained long-fiber nonwoven fabric are shown in Table 8. The obtained long-fiber nonwoven fabric had a smooth surface without pleats, but the fibers were partially fuzzed and it was poor in stretchability.

L: tangent lines P1, P2: two tangent points on the tangent line L D _max : apparent maximum fiber diameter of fiber F _A D _min : apparent minimum fiber diameter of fiber F _A

Claims (14)

A long-fiber nonwoven fabric, at least one surface of which is composed of fibers F _A mainly composed of thermoplastic resin A, wherein the ratio D _max /D _min of the apparent maximum fiber diameter D _max (μm) to the apparent minimum fiber diameter D _min (μm) of the fibers F _A is 1.2 to 5.0, the elongation recovery rate of the long-fiber nonwoven fabric is 50% to 99%, and the apparent density is 0.02 g/cm ³ to 0.20 g/cm ³ . 2. The long-fiber nonwoven fabric according to claim 1, wherein the long-fiber nonwoven fabric has a maximum breaking elongation E _max (%) of 120% or more and 400% or less. 3. The long-fiber nonwoven fabric according to claim 2, wherein the ratio E _max /E _min of the maximum breaking elongation E _max (%) to the minimum breaking elongation E _min (%) is 1.5 or more and 5.0 or less. 3. The long-fiber nonwoven fabric according to claim 1, wherein the fibers F _A have a crimp number per 25 mm of 0 to 49. The long-fiber nonwoven fabric according to claim 1 or 2, in which 90.1% by mass or more and 100.0% by mass or less of the thermoplastic resin A is a polyolefin-based polymer and/or a copolymer thereof. 3. The long-fiber nonwoven fabric according to claim 1 or 2, further comprising at least one long-fiber nonwoven fabric layer composed of fibers F _B having a thermoplastic resin B different from the thermoplastic resin A as a main component. The long-fiber nonwoven fabric according to claim 6, in which 90.1% by mass or more and 100.0% by mass or less of thermoplastic resin B is one or more types selected from the group consisting of polyolefin-based elastomers and polyurethane-based elastomers. The long-fiber nonwoven fabric according to claim 6 or 7, wherein the absolute value of the difference between the softening temperature T _S,A (°C) of the thermoplastic resin A and the softening temperature T _S,B (°C) of the thermoplastic resin B, |T _S,A -T _S,B |, is 10°C or more and 100°C or less. The long-fiber nonwoven fabric according to claim 6 or 7, wherein the fibers F _B contain a fatty acid amide compound, and the content thereof is 0.01% by mass or more and 5.0% by mass or less. A sanitary material, at least a portion of which is made of the long fiber nonwoven fabric described in claim 1 or 2. A sanitary material, at least a portion of which is composed of an elongated member to which the long-fiber nonwoven fabric described in claim 1 or 2 and the pleated long-fiber nonwoven fabric are bonded. forming a sheet having a layer that is a layer composed of fibers F _A having the thermoplastic resin A as a main component;
a step of pressing the sheet with a roll having a surface temperature of 0° C. or more and 120° C. or less to form a fused sheet;
The method for producing a long-fiber nonwoven fabric according to claim 1, further comprising a step of stretching the fused sheet in the width direction and/or the length direction in a range of 1.5 to 5.0 times. 13. The method for producing a long-fiber nonwoven fabric according to claim 12, wherein in the sheet-forming step, the sheet is a laminated sheet having at least one layer that will become a long-fiber nonwoven fabric layer, the layer being composed of fibers F _B having a thermoplastic resin B different from the thermoplastic resin A as a main component. The method for producing a long-fiber nonwoven fabric according to claim 12 or 13, wherein the linear pressure of the roll is 0.5 N/cm or more and 5.0 N/cm or less in the process of forming the fused sheet.