WO2020250481A1 - Laminated nonwoven fabric for absorbent article - Google Patents

Abstract

A laminated nonwoven fabric according to the present invention comprises a melt-blown layer (20) and a spun-bonded layer (10) laminated on one side or both sides of the melt-blown layer (20), wherein fibers (21) constituting the melt-blown layer (20) have a fiber diameter of less than 1 μm. In the laminated nonwoven fabric according to the present invention, a ratio tmax/tmin of a maximum thickness (tmax) to a minimum thickness (tmin) is greater than 2, or a filling rate which is a space occupation rate of fiber, is greater than 7.7%. Fibers (11) constituting the spun-bonded layer (10) preferably have a fiber aspect ratio of greater than 1.2 in a transverse section of the fibers (11).

Description

Laminated non-woven fabric for absorbent articles

The present invention relates to a laminated non-woven fabric for absorbent articles.

Conventionally, non-woven fabrics and the like have been used as constituent members in absorbent articles such as disposable diapers and sanitary napkins. For example, Patent Document 1 describes a non-woven fabric made of a single polymer spiral crimped fiber as a non-woven fabric for use in an absorbent article. Further, in Patent Document 1, a melt blow layer and a second spun bond layer are laminated in this order on a spun bond layer formed of the spiral crimped fibers, and the spun bond-melt blow-spun bond fiber is composed. It is described that a non-woven fabric having a three-layer structure is produced.

Special Table 2005-5171993

The present invention is a laminated non-woven fabric having a melt blow layer and a spunbond layer laminated on one side or both sides of the melt blow layer.
In the laminated nonwoven fabric of the present invention, preferably, the fibers constituting the melt blow layer have a fiber diameter of less than 1 μm.
The laminated nonwoven fabric of the present invention preferably has t _max / t _min, which is a ratio of the maximum thickness t _max to the minimum thickness t _min of the melt blow layer, of more than 2.
The laminated nonwoven fabric of the present invention preferably has a filling rate of more than 7.7%.
In a preferred embodiment, the laminated nonwoven fabric is a laminated nonwoven fabric for absorbent articles.

The present invention also includes a step of forming a spunbond layer by a spunbond method and a step of forming a meltblow layer by a meltblow method, and the meltblow layer and the spunbond layer laminated on one side or both sides of the meltblow layer. And the process of manufacturing a laminate with
This is a method for producing a laminated non-woven fabric having an embossing step of embossing the laminated body.
The method for producing a laminated non-woven fabric of the present invention preferably has a calendar step of subjecting the laminated body to a calendar process.
In a preferred embodiment, the laminated nonwoven fabric is a laminated nonwoven fabric for absorbent articles.
Other features of the invention will become apparent from the claims and description below.

FIG. 1 is a cross-sectional view schematically showing an embodiment of the laminated nonwoven fabric of the present invention. FIG. 2 is a schematic plan view of the laminated non-woven fabric shown in FIG. FIG. 3 is a perspective view of the laminated non-woven fabric shown in FIG. FIG. 4 is an enlarged view of part III shown in FIG. 5 (a) is a perspective view of an absorbent article including the laminated non-woven fabric shown in FIG. 1, and FIG. 5 (b) is a schematic cross-sectional view taken along the line Vb-Vb of FIG. 5 (a). FIG. 6 is a conceptual diagram showing an embodiment of the method for producing a laminated nonwoven fabric of the present invention. FIG. 7 is a schematic perspective view showing a part of the conventional laminated non-woven fabric in an enlarged manner.

Detailed description of the invention

As a leak-proof material for absorbent articles, a single-layer or multi-layered non-woven fabric may be used instead of the resin film from the viewpoint of flexibility and touch. By the way, since the water pressure resistance of the melt-blown non-woven fabric is improved by crushing the thickness and increasing the filling, it is conceivable to use the melt-blow non-woven fabric having the thickness reduced and the water pressure resistance increased as a leakage-proof material for absorbent articles. Be done. However, in the conventional general melt-blow non-woven fabric, even if the filling is high, when water pressure is applied, the fibers constituting the melt-blow non-woven fabric are further separated, and the fibers having a low fiber density are generated, so that the water pressure resistance is sufficiently sufficient. It is difficult to increase. In the present specification, high filling means increasing the space occupancy of fibers.

By laminating the melt blow layer and the spun bond layer as in Patent Document 1, the water pressure resistance can be increased as compared with the case of the melt blow non-woven fabric alone. FIG. 7 shows a schematic perspective view of the conventional laminated non-woven fabric 7. The laminated non-woven fabric 7 is a so-called SMS non-woven fabric in which the spunbond layer 70, the melt blow layer 80, and the spunbond layer 70 are laminated in this order. The melt blow layer 80 may have a portion where the density of the melt blow fibers 81 constituting the melt blow layer 80 is low, and such a portion becomes a hole 80A through which a liquid can easily pass. By laminating the span bond layer 70 on the melt blow layer 80, the spun bond fibers 71 constituting the spun bond layer 70 can block the holes 80A existing in the melt blow layer 80, so that the melt blow layer 80 can be closed. It is considered that the water pressure resistance can be improved by laminating the spunbond layer 70 on the surface. However, in order to use it as a leak-proof material for absorbent articles, further improvement in water pressure resistance is desired.

The present invention relates to a laminated non-woven fabric having improved water pressure resistance.

Hereinafter, the present invention will be described based on the preferred embodiment thereof.
The laminated nonwoven fabric of the present invention has a melt blow layer and a spunbond layer laminated on one side or both sides of the melt blow layer. The former is typically a spunbond-melt blow (SM) non-woven fabric, and the latter is typical. It is a spunbond-melt blow-spunbond (SMS) non-woven fabric.

The laminated nonwoven fabric of the present invention is preferably obtained by performing calendar processing on a laminate having a melt blow layer and a spunbond layer laminated on one side or both sides of the melt blow layer. Then, the melt blow layer having a small fiber diameter is highly filled, and at least one of the following conditions (1) or (2) is satisfied. As a result, the water pressure resistance is greatly improved even though it is a non-woven fabric, and exhibits a high level of water resistance suitable for use as a leak-proof material for absorbent articles.

Conditions (1) The ratio of the maximum thickness t _max to the minimum thickness t _min of the melt blow layer, t _max / t _min, is more than 2.
Condition (2) The filling rate (also simply referred to as filling rate), which is the space occupancy of the fibers, of the laminated non-woven fabric is more than 7.7%.

The laminated non-woven fabric of the present invention satisfies at least one of the above conditions (1) or (2), and preferably satisfies the above conditions (1) and (2).
Hereinafter, the laminated nonwoven fabric satisfying the condition (1) is also referred to as a laminated nonwoven fabric 1A, and the laminated nonwoven fabric satisfying the condition (2) is also referred to as a laminated nonwoven fabric 1B.
A preferable configuration common to the laminated non-woven fabrics 1A and 1B will be described by taking the laminated non-woven fabric 1 shown in FIGS. 1 to 3 satisfying the above conditions (1) and (2) as an example.

The laminated nonwoven fabric 1 shown in FIGS. 1 to 3 has a melt blow layer 20 and a span bond layer 10 laminated on both sides of the melt blow layer 20. The melt blow layer 20 is a layer formed by the melt blow method, and is composed of fibers 21 spun by the melt blow method. The spunbond layer 10 is a layer formed by the spunbond method, and is composed of fibers 11 spun by the spunbond method. Hereinafter, the fibers 21 spun by the melt blow method forming the melt blow layer 20 are also referred to as melt blow fibers, and the fibers 11 spun by the spun bond method forming the spun bond layer 10 are also referred to as spun bond fibers. Generally, the fiber diameter of the spunbond fiber is larger than the fiber diameter of the melt blow fiber.
In FIGS. 1 and 2, reference numeral X is an arbitrary direction along the plane direction of the laminated nonwoven fabric 1, and reference numeral Y in FIG. 2 is a direction orthogonal to the X direction in the plane direction. In FIG. 1, reference numeral Z is the thickness direction of the laminated non-woven fabric 1. As shown in FIGS. 1 and 2, the span bond layer 10 does not need to have the span bond fibers 11 present without gaps over the entire plane direction of the laminated nonwoven fabric 1, and may be present intermittently. ..

In general, since the fibers constituting the melt blow layer have a small fiber diameter, the melt blow layer has a high fiber density and exhibits water pressure resistance, but its strength is weak. To make up for this drawback, the melt blow layer is often laminated with a spunbond layer having a large fiber diameter. Since the fiber diameter of the fibers constituting the spunbond layer is larger than that of the melt blow layer, the spunbond layer has a low fiber density, and the spunbond layer alone does not contribute to the water pressure resistance performance. On the other hand, by laminating the spunbond layer on the melt blow layer, the region of the melt blow layer having a low fiber density is covered and sealed, so that the water pressure resistance is improved. However, according to the present invention, the effect of improving water pressure resistance is further enhanced.

In the laminated non-woven fabric 1, the fibers constituting the melt blow layer 20 have a fiber diameter of less than 1 μm. The laminated non-woven fabric 1 was obtained by, for example, performing a calendering process on the laminated body 2 having the melt blow layer 20 and the spunbond layer 10 laminated on the melt blow layer 20 (see FIG. 6).
As the melt blown nonwoven fabric, those having a fiber diameter of less than 1 μm are also known. However, the melt-blown nonwoven fabric used for absorbent articles usually has a fiber diameter of more than 1 μm. On the other hand, in the melt blow layer in the laminated nonwoven fabric 1 and the laminated body 2, the fiber diameter of the constituent fibers is less than 1 μm. By setting the fiber diameter of the fibers constituting the melt blow layer to less than 1 μm, the fiber density is increased in the entire area of the melt blow layer. Thereby, it is possible to suppress the generation of a region having a low fiber density in the melt blow layer. Then, by performing calendar processing on the laminate 2 having the melt blow layer and the spunbond layer, the effect of improving the water pressure resistance can be surely obtained.

From the viewpoint of ensuring that the effect of improving water pressure resistance can be obtained, the fiber diameter of the fibers 21 constituting the melt blow layer 20 is less than 1 μm in both the laminated non-woven fabric 1 and the laminated body 2 before calendering. It is preferably 0.95 μm or less, more preferably 0.9 μm or less, and further preferably 0.85 μm or less.
The lower limit is not particularly limited, but from the viewpoint of stable spinning by the melt blow method, it is realistic to set it to 0.1 μm or more.
The fiber diameter of the fibers 21 constituting the melt blow layer 20 is preferably 0.1 μm or more and less than 1 μm, more preferably 0.1 μm or more and 0.95 μm or less, and further preferably 0.1 μm or more and 0.9 μm or less. Yes, more preferably 0.1 μm or more and 0.85 μm or less.

FIG. 6 is a diagram showing an example of a method for manufacturing the laminated non-woven fabric 1. The laminated body 2 to be calendered is not limited to the one shown in FIG. For example, a spunbonded non-woven fabric unwound from a roll-shaped raw fabric and a melt-blown non-woven fabric unwound from a roll-shaped raw fabric are laminated, or a melt blown fabric is melt-blown on a spunbonded non-woven fabric unwound from a roll-shaped raw fabric. The fiber may be sprayed, or the melt blow layer may have a spunbond layer on only one side. Details of the manufacturing method shown in FIG. 6 will be described later.

The fiber diameter of the fibers constituting the melt blow layer is measured by the following method.
<Measuring method of fiber diameter of fibers constituting the melt blow layer>
Ten small pieces of sample are randomly cut out from the laminated non-woven fabric to be measured using a razor. A scanning electron microscope (SEM) is used to focus and observe the part of the melt blow layer that does not include the embossed portion. Set the observation magnification so that 20 to 30 melt blow fibers are reflected in the field of view, and take a picture. The observation magnification is, for example, 4500 times or more. The fiber diameter is measured so that each fiber in the field of view is counted once. If the cross section of the fiber is a perfect circle, the diameter is the fiber diameter, if it is elliptical, the length of the major axis is the fiber diameter, and if it is neither a perfect circle nor an ellipse, the cross section in the cross section of the fiber. The length of the wire having the longest length is defined as the fiber diameter. For each of the 10 small piece samples measured in this way, the fiber diameters of 20 or more fibers, totaling 200 or more fibers, are measured. Calculate the average value of them. The average value is obtained by rounding off the second decimal place on the micrometer scale, and the value is taken as the fiber diameter of the fibers constituting the melt blow layer.
When cutting out a small piece sample from a laminated non-woven fabric using a shaving sword, the laminated non-woven fabric is immersed in liquid nitrogen, and then the small piece sample is cut out within 30 seconds after the laminated non-woven fabric is taken out from liquid nitrogen. Use a razor with a blade thickness of 0.23 mm. The laminated non-woven fabric is cut by raising a razor in a direction perpendicular to the plane direction of the laminated non-woven fabric.
<Measurement method of fiber diameter of fibers constituting melt blow layer>, <Measurement method of minimum thickness t _min and maximum thickness t _max of melt blow layer>, <Measurement of minor axis and major axis length of spunbond fiber> using SEM Liquid nitrogen is always used for <method>, <determination method>, <measurement method for maximum fiber width and minimum fiber width>, and <measurement method for fiber diameter of fibers constituting the spunbond layer>.
For <Measuring method of packing rate of laminated non-woven fabric>, <Measuring method of resin density>, <Measuring method of filling rate of melt blow layer>, and <Measuring method of grain size>, liquid nitrogen is added as necessary. Use.
When the laminated non-woven fabric to be measured is incorporated in a product such as an absorbent article, cold spray is sprayed on the product to solidify the adhesive, and the laminated non-woven fabric to be measured is carefully peeled off and taken out. The fiber diameter is measured in the laminated non-woven fabric at a portion where the fiber maintains its shape, avoiding the embossed portion. The extraction means and measurement points are also applied to other measurements in the present specification. The SEMs used in the measurements herein are all JCM-6000 PLUS manufactured by JEOL Ltd.

In general, when compression deformation is not performed, the fiber diameter of a normal thermoplastic fiber in the longitudinal direction of the fiber is constant. Also in the present invention, the fiber diameter of the melt blow fiber and the fiber diameter of the spunbond fiber are constant in the longitudinal direction, except for the portion that is compression-deformed.
In general, the cross section of a thermoplastic fiber spun using a normal circular (round) nozzle is round and constant over its longitudinal direction unless it is subjected to compression deformation or the like. Also in the present invention, the cross-sectional shapes of the melt blow fibers and the spunbond fibers are substantially circular except for the compression-deformed portion, and each of them is constant in the longitudinal direction of the fibers.

When the laminated non-woven fabric 1 is manufactured by compressing the laminated body 2 by calendar processing or the like, the laminated non-woven fabric 1 is crushed in the thickness direction Z. As a result, both the laminated non-woven fabric 1 as a whole and the melt blow layer 20 are highly filled by reducing the interfiber distance. Further, by compressing the melt blow layer 20 and the spun bond layer 10 in a laminated state, the spun bond fibers 11 are sunk into the melt blow layer 20 in a portion where a large number of spun bond fibers 11 are microscopically present. (See Fig. 1).
The laminated non-woven fabrics 1A and 1B satisfy the above conditions (1) and (2) by, for example, such an action. As a result, it exhibits significantly superior water resistance as compared with the conventional SMS non-woven fabric which has a spunbond layer and a melt blow layer but is not subjected to calendering. Hereinafter, the laminated nonwoven fabrics 1A and 1B will be further described. Water resistance can be evaluated using water pressure as an index, and the higher the water pressure, the better the water resistance.

[Laminated non-woven fabric 1A]
As shown in FIG. 1, the laminated nonwoven fabric 1A is in a state in which the spunbond fibers 11 constituting the spunbond layer 10 are embedded in the melt blow layer 20. As a result, the laminated nonwoven fabric 1A has a portion in which the thickness of the melt blow layer 20 is relatively large and a portion in which the thickness of the melt blow layer 20 is relatively small when compared in the plane direction of the laminated nonwoven fabric 1A. In particular, the portion where the spunbond fibers 11 are relatively densely present on the meltblow layer 20 is thicker than the portion where the spunbond fibers 11 are relatively sparsely present. Is getting smaller.

In the laminated nonwoven fabric 1A, the spunbond fibers 11 are partially embedded in the melt blow layer 20, so that the fiber restraint portion in which the movement of the melt blow fibers 21 in the melt blow layer 20 is suppressed by the spunbond fibers 11 in the laminated nonwoven fabric 1A. 4 is formed. If the movement of the melt blow fibers 21 is suppressed in the fiber restraint portion 4, for example, even if water pressure is applied to the melt blow layer, the melt blow fibers 21 are more difficult to separate. Then, the melt blow layer 20 is prevented from having a portion having a low fiber density that reduces the water pressure resistance.
Since the laminated non-woven fabric 1A satisfies the above condition (1), the spunbond fiber 11 is largely sunk into the melt blow layer 20, and the movement suppressing force of the melt blow fiber 21 in the fiber restraint portion 4 is high. Moreover, the fiber restraint portions 4 formed by pressing the span bond fibers 11 constituting the span bond layer 10 are formed in a state of being dispersed in the plane direction of the laminated non-woven fabric 1A.
According to the laminated non-woven fabric 1A, since the fiber restraining portions 4 having a strong movement binding force are formed in a state of being dispersed in the plane direction, a laminated non-woven fabric having further improved water pressure resistance can be obtained. ..

The minimum thickness t _min and the maximum thickness t _max of the melt blow layer 20 are measured by the following methods.
<Measuring method of minimum thickness t _min and maximum thickness t _max of melt blow layer>
The laminated non-woven fabric is cut with a razor at a plurality of locations separated in the plane direction. At that time, a cut surface that does not include the embossed portion is obtained. The cut surface at each cut portion is observed by SEM at a magnification of about 100 to 300 times. For the melt blow layer in the range of 400 μm in width centered on the center of each cut surface in the plane direction, the thicknesses of the minimum thickness portion and the maximum thickness portion are measured, respectively. The average value is calculated by averaging the thickness of the minimum portion and the thickness of the maximum portion of the melt blow layer on each cut surface measured in this manner. Let these average values be the minimum thickness t _min and the maximum thickness t _max , respectively. The cut surfaces to be observed are 5 or more, and the measurement is performed so that the width of the measurement range is 2 mm or more (400 μm × 5 or more) in total.

The ratio of the maximum thickness t _max to the minimum thickness t _min of the melt blow layer 20 is t _max / t _min , which is preferably more than 2 from the viewpoint of suppressing the movement of the melt blow fibers 21 and further improving the water resistance. Is 2.5 or more, more preferably 3 or more.
From the viewpoint of maintaining excellent flexibility as a non-woven fabric, it is preferably 14 or less, more preferably 13.5 or less, and further preferably 10 or less.
From the viewpoint of compatibility between them, it is preferably more than 2 and 14 or less, more preferably 2.5 or more and 13.5 or less, and further preferably 3 or more and 10 or less.

The minimum thickness t _min of the melt blow layer 20 is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of maintaining excellent flexibility as a non-woven fabric.
From the viewpoint of suppressing the movement of the melt blow fiber 21 and further increasing the water resistance, it is preferably 45 μm or less, and more preferably 20 μm or less.
From the viewpoint of compatibility between them, it is preferably 5 μm or more and 45 μm or less, and more preferably 10 μm or more and 20 μm or less.

The maximum thickness _tmax of the melt blow layer 20 is preferably 65 μm or more, more preferably 95 μm or more, from the viewpoint of maintaining excellent flexibility as a non-woven fabric.
From the viewpoint of further enhancing the water resistance, it is preferably 130 μm or less, and more preferably 100 μm or less.
From the viewpoint of compatibility between them, it is preferably 65 μm or more and 130 μm or less, and more preferably 95 μm or more and 100 μm or less.

[Laminated non-woven fabric 1B]
The laminated non-woven fabric 1B is obtained by, for example, performing a calendering process on a laminated body 2 having a melt blow layer 20 and a spunbond layer 10 laminated on the melt blow layer 20. As a result, the filling rate of the laminated non-woven fabric as a whole is high, and the above condition (2) is satisfied.
In the laminated non-woven fabric 1B, when the above condition (2) is satisfied, the spunbond fibers 11 constituting the spunbond layer 10 adhere to the melt blow layer 20. Further, even if the melt blow layer 20 has a portion having a low fiber density such as the hole 80A shown in FIG. 7, the portion can be effectively covered and the performance of blocking the permeation of the liquid from the portion is excellent. ..
According to the laminated non-woven fabric 1B, in addition to the above-mentioned effect of improving the water pressure resistance by increasing the filling of the melt blow layer 20 having a small fiber diameter of the constituent fibers, the effect of improving the water pressure resistance by adhering the spunbond fibers 11 can be obtained. Therefore, according to the laminated non-woven fabric 1B, a high water pressure resistance can be obtained.

The filling rate of the laminated non-woven fabric is measured by the following method.
<Measuring method of filling rate of laminated non-woven fabric>
A 10 cm × 10 cm test piece is cut out from the laminated non-woven fabric to be measured using a razor. If it is not possible to cut out a 10 cm x 10 cm test piece, cut out a test piece with as large an area as possible. A laser thickness gauge is used to measure the thickness under a load of 50 Pa. Measure at three points from one test piece, and use the average value as the thickness of the laminated non-woven fabric. Next, the mass of the test piece is measured, and the value divided by the area is used as the basis weight of the laminated non-woven fabric. The filling rate of the laminated non-woven fabric is calculated by {the basis weight of the laminated non-woven fabric / (thickness of the laminated non-woven fabric × density of resin)} × 100.
The laser thickness gauge used in the present specification is ZSLD80 manufactured by OMRON Corporation.

The above "resin density" can be measured by the following method.
<Measuring method of resin density>
The laminated non-woven fabric taken out is pressed with a lab press (manufactured by Toyo Seiki Seisakusho Co., Ltd., model P2-30) at 180 ° C. with a two-stage press (low pressure: 5 kg / cm3, high pressure: 150 kg / cm3) for 1 minute, and then cooled. To make a film by 1 minute. Then, a sample of 10 × 10 cm is cut out from a place where air is not mixed using a razor, the mass is measured, and then the value calculated by dividing by the volume is used as the resin density. The volume of the produced film can be calculated by multiplying the thickness of the film by the area. The film thickness can be measured with a laser thickness gauge.

The filling rate of the laminated non-woven fabric 1B is preferably more than 7.7%, more preferably 10% or more, still more preferably 14% or more, from the viewpoint of improving the water pressure resistance.
From the viewpoint of improving the feel of the laminated non-woven fabric 1B, it is preferably 35% or less, more preferably 30% or less, and further preferably 25% or less.
From the viewpoint of compatibility between them, it is preferably more than 7.7% and 35% or less, more preferably 10% or more and 30% or less, and further preferably 14% or more and 25% or less.

The preferable configurations of the laminated nonwoven fabrics 1A and 1B will be further described with reference to the laminated nonwoven fabric 1 shown in FIGS. 1 to 3.
The laminated nonwoven fabric 1 preferably has a flat cross-sectional shape of the spunbond fibers 11. Specifically, as shown in FIG. 4, the spunbond fiber 11 has a flat shape having a long axis and a short axis in a cross section in a direction orthogonal to the longitudinal direction of the spunbond fiber 11. The laminated non-woven fabric 1 preferably has a fiber aspect ratio of the spunbond layer of more than 1.2. That is, "flat" here means that the fiber aspect ratio is more than 1.2. In the laminated non-woven fabric 1, it is sufficient that some of the spunbond fibers 11 constituting the spunbond layer 10 have a fiber aspect ratio of more than 1.2, but all the spunbond fibers 11 have a fiber aspect ratio of 1.2. It is preferably super. This can be produced by crushing the spunbond fibers 11 by, for example, calendering.

The length L of the long axis in the cross section of the spunbond fiber 11 is the longest distance between any two points on the outer circumference of the cross section of the spunbond fiber 11 extracted by microscopic observation. With the line segment connecting the points as the major axis, the length L of the major axis is referred to (see FIG. 4). On the other hand, the short axis refers to the length S of the short side when a rectangle having a long side parallel to the long axis determined as described above and circumscribing the outer circumference is drawn (see FIG. 4). ..

The laminated nonwoven fabric 1 has a fiber aspect ratio of more than 1.2, and the spunbond fibers 11 have a flat shape, so that the spunbond fibers 11 cover the surface of the melt blow layer 20 with a wider area. be able to. Therefore, even if the melt blow layer 20 has a portion having a low fiber density such as the hole 80A shown in FIG. 7, the spunbond fiber 11 can effectively cover the portion and the liquid from the portion can be covered. Excellent performance to prevent permeation.
Since the laminated nonwoven fabric 1 has a fiber aspect ratio of more than 1.2, it is made of flat spunbond fibers 11 in addition to the effect of improving water pressure resistance by increasing the filling of the melt blow layer 20 having a small fiber diameter of the constituent fibers described above. The above effect is achieved. Therefore, according to the laminated non-woven fabric 1 having a fiber aspect ratio of more than 1.2, a high water pressure resistance can be obtained.

The fiber aspect ratio of the spunbond fiber 11 is preferably more than 1.2, more preferably 1.6 or more, from the viewpoint of covering the surface of the melt blow layer with a wider area.
Further, from the viewpoint of maintaining excellent flexibility as a non-woven fabric, it is preferably 2.5 or less, more preferably 2.2 or less.
From the viewpoint of compatibility between them, it is preferably more than 1.2 and 2.5 or less, and more preferably 1.6 or more and 2.2 or less.
<Measurement method of minor axis and major axis length of spunbond fiber>
A measuring piece having a cut surface along the thickness direction is cut out from any five points separated in the plane direction of the laminated non-woven fabric by a razor. At that time, a cut surface that does not include the embossed portion is obtained. The portion of the cut surface of each measuring piece that does not include embossing is observed by SEM at a magnification of 300 times. Ten or more spunbond fibers 11 are randomly selected from each of the cut surfaces of the five measurement pieces, and the length of the minor axis and the length of the major axis are obtained for a total of 50 or more spunbond fibers of the five measurement pieces. The values are measured, and the average values thereof are defined as the length S of the minor axis and the length L of the major axis.

From the viewpoint of increasing the area covering the melt blow layer and improving the water pressure resistance of the spunbond fiber 11, it is preferable that the long axis L of the cross section is oriented in the direction along the plane direction of the laminated nonwoven fabric 1. Whether or not the long axis L of the cross section is oriented in the direction along the plane direction of the laminated nonwoven fabric 1 is determined by the following method.
<Judgment method>
A measuring piece having a cut surface along the thickness direction is cut out from any five locations separated in the plane direction of the laminated nonwoven fabric 1 by a razor. At that time, a cut surface that does not include the embossed portion is obtained. The cut surface of each measuring piece that does not include the embossed portion is observed by SEM at a magnification of 300 times. Ten or more spunbond fibers 11 are randomly selected from each of the cut surfaces of the five measurement pieces. It is determined which of the major axis and the minor axis of the spunbond fibers 11 is closer to the direction parallel to the plane of the laminated nonwoven fabric. For each of the five measurement pieces, the proportion of spunbond fibers having a major axis closer to the plane parallel to the plane of the laminated non-woven fabric than the minor axis is calculated out of 10 or more spunbond fibers totaling 50 or more. When the ratio is 75% or more, it is determined that the long axis L of the cross section is oriented in the direction along the plane direction of the laminated nonwoven fabric 1. The proportion of the spunbond fibers in the direction parallel to the plane of the laminated nonwoven fabric is preferably more than 75%, more preferably 80% or more, still more preferably 85% or more, and 100% or less.

The spunbond fiber 11 of the laminated non-woven fabric 1 is formed by subjecting the laminated non-woven fabric 1 to a calendar process, so that a strongly pressed portion and a weakly pressed portion are formed in one spunbond fiber 11. Have. The strongly pressed portion of the spunbond fiber 11 has a large flatness and a flatter cross-sectional shape. The weakly pressed portion of the spunbond fiber 11 has a cross-sectional shape that is less flat and closer to a perfect circle. That is, it is preferable that the spunbond fiber 11 has a portion having a different fiber width in the longitudinal direction of the spunbond fiber 11. Here, the fiber width means the length of the line having the longest transverse length in the cross section of the fiber. The ratio of the maximum fiber width to the minimum fiber width (maximum fiber diameter / minimum fiber diameter) in the spunbond fiber 11 is preferably more than 1.1, more preferably more than 1.4.
Further, it is preferably 2.5 or less, more preferably 2 or less, in order to avoid local pressure, keep the portion soft, and keep the non-woven fabric soft to the touch.
Further, in order to apply sufficient pressurization, it is preferably more than 1.1 and 2.5 or less, and more preferably more than 1.4 and 2 or less.
When the cross-sectional shape of the fiber is flat before calendering, that is, from the time of spinning, the fiber width does not change significantly in the longitudinal direction of the fiber, and the maximum fiber with respect to the minimum fiber width. The width ratio does not fall within the above range.

The maximum fiber width and the minimum fiber width of the spunbond fiber 11 are measured as follows. <Measuring method of maximum fiber width and minimum fiber width>
A measuring piece having a cut surface along the thickness direction is cut out by a razor from any five points separated in the plane direction of the laminated non-woven fabric. At that time, a cut surface that does not include the embossed portion is obtained. The portion of the cut surface of each measuring piece that does not include embossing is observed by SEM at a magnification of 300 times. Ten or more spunbond fibers 11 are randomly selected from each of the cut surfaces of the five measurement pieces, and the cross-sectional length of the fibers is the longest in the cross section for a total of 50 or more spunbond fibers of the five measurement pieces. The length of the line is measured, and the average value of the upper five fibers is set as the maximum fiber width, and the average value of the lower five fibers is set as the minimum fiber width. The value obtained by dividing the maximum fiber width by the minimum fiber width is rounded to the first decimal place to obtain the ratio of the minimum fiber width to the maximum fiber width.

The melt blow layer 20 of the laminated non-woven fabric 1 is preferably clogged and has small voids between fibers from the viewpoint of improving water pressure resistance. Specifically, it is preferable that the filling rate per unit space and the basis weight, which is the mass per unit area, are high.

The filling rate of the melt blow layer 20 is preferably more than 4.1%, more preferably 5% or more, still more preferably 6% or more, from the viewpoint of improving the water pressure resistance.
From the viewpoint of maintaining excellent flexibility as a non-woven fabric, it is preferably 11% or less, more preferably 10% or less, still more preferably 9% or less.
From the viewpoint of compatibility between them, it is preferably more than 4.1% and 11% or less, more preferably 5% or more and 10% or less, and further preferably 6% or more and 9% or less.
<Measurement method of filling rate of melt blow layer>
A 10 cm × 10 cm test piece is cut out from the laminated non-woven fabric using a razor. If it is not possible to cut out a 10 cm x 10 cm test piece, cut out a test piece with as large an area as possible. Carefully peel off the span bond layer from the test piece with your hand or tweezers to remove the melt blow layer. Using a laser thickness gauge, measure the thickness under a load of 50 Pa, and use the average value as the thickness of the melt blow layer. Next, the weight of the melt blow layer is measured, and the value obtained by dividing by the sheet area of the laminated non-woven fabric is used as the basis weight of the melt blow layer. The filling rate of the melt blow layer is calculated by {Metsuke of the melt blow layer / (thickness of the melt blow layer x density of resin)} x 100.
The above-mentioned "resin density" is measured by using the same means as the above-mentioned <method for measuring resin density>.

The basis weight of the melt blow layer 20 is preferably 5 g / m ² or more, and more preferably 7.5 g / m ² or more.
Further, it is preferably 15 g / m ² or less, more preferably 12.5 g / m ² or less.
Further, it is preferably 5 g / m ² or more and 15 g / m ² or less, and more preferably 7.5 g / m ² or more and 12.5 g / m ² or less.

The basis weight is measured by the following method.
<Metsuke measurement method>
In the case of measuring the basis weight of the laminated non-woven fabric, a 10 cm × 10 cm test piece is cut out from the laminated non-woven fabric to be measured using a razor. If it is not possible to cut out a 10 cm x 10 cm test piece, cut out a test piece with as large an area as possible. Next, the mass of the test piece is measured, and the value divided by the area is used as the basis weight of the laminated non-woven fabric.
In the case of measuring the basis weight of the melt blow layer or the spunbond layer, a 10 cm × 10 cm test piece is cut out from the laminated non-woven fabric using a razor. If it is not possible to cut out a 10 cm x 10 cm test piece, cut out a test piece with as large an area as possible. Carefully remove the melt blow layer or spunbond layer from the test piece with your hands or tweezers. Then, the mass of the test piece is measured, and the value obtained by dividing by the sheet area of the laminated non-woven fabric is used as the basis weight of the melt blow layer or the spun bond layer.

From the viewpoint of improving the water resistance of the laminated non-woven fabrics 1A and 1B, the fiber diameter of the spunbond fiber 11 is preferably 35 μm or less, more preferably 30 μm or less.
Further, from the viewpoint of stable spinning by the spunbond method, it is realistic to set the thickness to 16 μm or more.
From the viewpoint of compatibility between them, it is preferably 16 μm or more and 35 μm or less, and more preferably 16 μm or more and 30 μm or less. The fiber diameter of the spunbond fiber 11 means the length of the major axis when the cross section of the spunbond fiber 11 has a major axis and a minor axis.
From the viewpoint of improving the water resistance of the laminated non-woven fabrics 1A and 1B, the fiber diameter of the spunbond fiber 11 is preferably 30 μm or less, more preferably 27 μm or less before compression by calendar processing or the like.
Further, from the viewpoint of stable spinning by the spunbond method, it is realistic to set the thickness to 10 μm or more.
From the viewpoint of compatibility between them, it is preferably 10 μm or more and 30 μm or less, and more preferably 10 μm or more and 27 μm or less.
<Measuring method of fiber diameter of fibers constituting the spunbond layer>
Three small samples are cut out from the laminated non-woven fabric to be measured using a razor. SEM is used to focus on the part of the spunbond layer that does not include the embossed portion. Take a picture with an observation magnification of, for example, 300 to 500 times so that 5 to 10 fibers can be seen in the field of view, and measure the maximum and minimum fiber diameters for each fiber in the field of view. To do. The fibers that make up the spunbond layer are calculated by calculating the average value of the fiber diameter including the maximum and minimum values of at least 15 fibers and rounding off the first decimal place on the micrometer scale. The fiber diameter of.

The water pressure resistance of the laminated non-woven fabric 1 is preferably 1600 mmAq. From the viewpoint of preventing liquid from leaking through the leak-proof material even when used as a leak-proof material for an absorbent article. Above, more preferably 1800 mmAq. That is all.
Although not particularly limited, 5000 mmAq. It is realistic to do the following.
From the viewpoint of compatibility between them, preferably 1600 mmAq. More than 5000 mm Aq. Hereinafter, more preferably, 1800 mmAq. More than 5000 mm Aq. It is as follows.

The water pressure resistance can be measured by the following method.
<Measurement method of water pressure resistance>
Using the laminated non-woven fabric to be measured, the measurement is performed in accordance with the water resistance test (hydrostatic pressure method) A method (low water pressure method) of JIS L1092-1998. In the water resistance test, a nylon mesh sheet (pore size: 133 μm, thickness: 121 μm, manufactured by Kurabo Industries Ltd., DO-ML-20) is placed on the test piece for measurement. If the size of the test piece is less than the specified size, a device having a reduced measurement area so that water hits the test piece in an area that can be collected can be assembled, and the water pressure resistance can be measured by the same method. The measurement is performed on three laminated non-woven fabrics, and the average value is taken as the water pressure resistance of the laminated non-woven fabric.

The laminated nonwoven fabric of the present invention is suitably used as a laminated nonwoven fabric for absorbent articles. The absorbable article is mainly used for absorbing and retaining body fluids excreted from the body such as urine and menstrual blood. Absorbent articles include, but are not limited to, disposable diapers, sanitary napkins, incontinence pads, panty liners, etc., and broadly include articles used for absorbing liquid discharged from the human body. To do.
The absorbent article typically comprises a front surface material, a back surface material, and a liquid-retaining absorber interspersed between the front surface material and the back surface material.
The surface material is typically liquid permeable.
The backing agent is typically poorly permeable or water repellent, but may be liquid permeable.
The laminated non-woven fabric of the present invention is particularly suitable as a leak-proof material for such absorbent articles. Examples of the leak-proof material for the absorbent article include a back surface material and a sheet material for forming a three-dimensional gather.

FIG. 5 shows an absorbent article 3 which is an example of an absorbent article having the laminated nonwoven fabric of the present invention. FIG. 5B exaggerates the thickness of the laminated non-woven fabric 1. The absorbent article 3 has a skin-facing surface and a non-skin-facing surface opposite to the skin-facing surface. The absorbent article 3 includes a liquid-permeable surface material 32 and a liquid-retaining absorber 34 arranged on the non-skin facing surface side of the surface material 32. The laminated non-woven fabric 1 is arranged on the non-skin facing surface side of the absorber 34. The laminated non-woven fabric 1 is used as a backing material for preventing the liquid absorbed by the absorber 34 from leaking from the non-skin facing surface of the absorbent article.

In the present specification, the "skin facing surface" is a surface of the absorbent article or its constituent members (for example, the absorber 34) that is directed toward the skin side of the wearer when the absorbent article is worn, that is, relatively of the wearer. The side closer to the skin, the "non-skin facing surface" is the side of the absorbent article or its constituents that is opposite to the skin side when the absorbent article is worn, that is, toward the side relatively far from the wearer's skin. It is the surface to be. The term "when worn" as used herein means a state in which the normal proper wearing position, that is, the correct wearing position of the absorbent article is maintained.

Since the absorbent article 3 has the laminated non-woven fabric 1 having a high water pressure resistance on the non-skin facing surface side of the absorber 34, the liquid absorbed by the absorber 34 effectively leaks to the outside. Be prevented. In addition, since the laminated non-woven fabric 1 is a non-woven fabric, the feel and appearance of the outer surface of the absorbent article 3 are also improved. In the laminated non-woven fabric 1, it is preferable that the span bond layer 10 is directed to the non-skin facing surface. When the laminated nonwoven fabric 1 is an SM nonwoven fabric, it is preferable that the melt blow layer 20 is arranged on the skin facing surface side and the span bond layer 10 is arranged on the non-skin facing surface side. When the laminated non-woven fabric 1 is an SMS non-woven fabric, any spunbond layer 10 may be directed to a non-skin facing surface. That is, including the case where the spunbond layers 10 are provided on both sides of the meltblow layer 20, the meltblow layer having a fiber diameter of less than 1 μm and a strength generally lower than that of the spunbond fiber is more than the spunbond layer 10. It is preferable to arrange the laminated non-woven fabric 1 on the side of the absorber 34 from the viewpoint of preventing damage due to friction of the laminated nonwoven fabric 1.

The absorbent article 3 shown in FIG. 5 is a so-called deployable diaper. It has a crotch part A in the central part in the longitudinal direction, and one part of both parts extending in front of and behind the crotch part A is the dorsal side part B, and the other part is the ventral side part C. .. Fastening tapes 35 are provided on both sides of the dorsal portion B. A landing zone 36 for fastening the fastening tape 35 is provided on the non-skin facing surface of the ventral side C (the surface facing the wearer's skin side when worn). The fastening tape 35 is fixed to the side flap portions 31 existing on both sides of the dorsal side portion B in the width direction. The absorbent article 3 has three-dimensional gathers 37 on both sides in the longitudinal direction. The side flap portion 31 is composed of a laminated body of a sheet 38 for forming a three-dimensional gather 37 and a laminated non-woven fabric 1. The sheet 38 for forming the three-dimensional gather 37 has a thread-like or band-shaped elastic member 62 extending in the longitudinal direction of the absorbent article 3. Further, on the outer edge side in the width direction of the absorbent article 3, a plurality of thread-like elastic members 63 are fixed between the laminated non-woven fabric 1 and the sheet 38 for forming the three-dimensional gather 37 along the longitudinal direction. ing.

The absorbent article may be a pants-type diaper. Pants-type diapers typically have a crotch in the center of the longitudinal direction, the dorsal part, which is one of the two parts extending in front of and behind the crotch, and the other. It has a ventral part, which is a site. Both sides of the dorsal side and both sides of the ventral side are joined to each other to form a pair of side seals. Then, a waist opening through which the wearer's body is passed and a pair of leg openings through which the wearer's lower limbs are passed are formed.

Next, the method for producing the laminated non-woven fabric of the present invention will be described based on a preferred embodiment thereof with reference to the drawings. FIG. 6 shows an outline of an example of the method for producing the above-mentioned laminated nonwoven fabric 1 as an embodiment of the method for producing the laminated nonwoven fabric of the present invention. The method for producing the laminated nonwoven fabric 1 of the present embodiment includes a step of manufacturing a laminate 2 in which the spunbond layer 10 is laminated on one side or both sides of the melt blow layer 20, an embossing step of embossing the laminate 2, and the lamination. It has a calendar process in which the body 2 is subjected to calendar processing (see FIG. 6). In the method for producing a laminated non-woven fabric of the present invention, either the embossing step or the calendar step may be performed first, the calendar step may be performed after the embossing step, or the embossing step may be performed after the calendar step. In this embodiment, the calendar process is performed after the embossing process.

The step of manufacturing the laminate 2 includes a step of forming the span bond layer 10 by the span bond method and a step of forming the melt blow layer 20 by the melt blow method.
In the manufacturing method of the present embodiment, first, the spunbond fibers 11 are spun from the spinneret of the first spinning head 51 arranged above the conveyor (not shown) and deposited in a web shape on the conveyor. The spunbond layer 10 is formed. Next, the formed spunbond layer 10 is conveyed on a transfer conveyor (not shown) in one direction (MD direction, which means Machine Direction, meaning transfer direction) indicated by the symbol MD. During the transfer, the melt blow fibers 21 are spun from the spinneret of the second spinning head 52 arranged above the transfer conveyor (not shown) and deposited directly on the spunbond layer 10. As a result, the melt blow layer 20 is formed on the spun bond layer 10, and the spun bond-melt blow laminate 2A is formed. Next, the spunbond-melt blow laminate 2A is subsequently conveyed in the MD direction on a transfer conveyor (not shown). During the transfer, the spunbond fibers 11 are spun from the spinneret of the third spinning head 53 arranged above the transfer conveyor (not shown) and deposited directly on the melt blow layer 20. As a result, the spunbond layer 10 is formed on the meltblow layer 20, and the spunbond-meltblow-spanbond laminate 2 (hereinafter, also referred to as the laminate 2) is formed.

Next, perform the embossing process. Specifically, the laminated body 2 is conveyed in the MD direction and supplied between the embossing rolls 54 and the anvil rolls 55 facing each other, and the laminated body 2 is embossed. The embossing step is preferably performed in a state where the fibers contained in the laminate 2, that is, the spunbond fibers 11 and the melt blow fibers 21 are heated to a temperature equal to or higher than the melting point. By performing the embossing step in a state where the laminated body 2 is heated, an embossed portion connecting between the layers of the laminated body 2 is formed in the laminated body 2, and each layer of the laminated body 2 is integrated to form the laminated body 2. Can be a non-woven fabric.

Next, a calendar process is performed. Specifically, the embossed laminate 2 is conveyed in the MD direction and supplied between the pair of anvil rolls 56 and 57, and the laminate 2 is subjected to calendar processing.
The anvil rolls 56 and 57 used for calendering typically have a smooth surface.
The calendar step is preferably performed at a temperature lower than the melting point of the fibers contained in the laminate 2, that is, the spunbond fibers 11 and the melt blow fibers 21.
The laminated body 2 is crushed in the thickness direction of the laminated body 2 by being subjected to calendar processing, and the span bond layer 10 is sunk into the melt blow layer 20 to produce the laminated non-woven fabric 1.
The embossing step and the calendar step can be performed in any order, but it is preferable to perform the embossing step first from the viewpoint of stabilizing the laminated structure of the laminated non-woven fabric 1.
According to the manufacturing method of the present embodiment, the laminated nonwoven fabric 1 having significantly improved water pressure resistance can be easily manufactured.

Normally, in the melt blow method or the spun bond method, the resin is melted and spun, so that the temperature of the melt blow layer 20 or the spun bond layer 10 immediately after being formed may be higher than room temperature. In the present embodiment, the laminated body 2 may be subjected to calendar processing after the rough heat of the laminated body 2 is removed, or the laminated body 2 may be subjected to calendar processing before the rough heat of the laminated body 2 is removed. Good. In the present embodiment, since the calendar processing is performed offline, which is not continuous with the spinning line, the calendar processing is performed after the rough heat is removed. As a means for removing the rough heat, for example, leaving the laminate 2 under a temperature condition lower than the temperature of the laminate 2, blowing an air stream on the laminate 2, and not being continuous with the spinning line. Examples include offline processing. Further, when the calendar processing is performed before the rough heat is removed, the calendar processing can be performed on the laminated body 2 in a soft and easily crushed state, so that the filling rate of the laminated non-woven fabric 1 can be further increased and the water pressure resistance can be increased. It can be further improved.

The linear pressure in the calendar process is preferably 2 N / mm or more, more preferably 4 N / mm or more, still more preferably 10 N / mm or more, from the viewpoint of embedding the span bond layer 10 in the melt blow layer 20.
From the viewpoint of preventing the spunbond fiber 11 from penetrating the melt blow layer 20 and forming a hole in the melt blow layer 20, it is preferably 40 N / mm or less, more preferably 30 N / mm or less, and further preferably 25 N / mm or less. ..
From the viewpoint of compatibility between them, it is preferably 2 N / mm or more and 40 N / mm or less, more preferably 4 N / mm or more and 30 N / mm or less, and further preferably 10 N / mm or more and 25 N / mm or less.
The method for producing a laminated non-woven fabric of the present invention may include a niping process using a pair of smoothing rolls in addition to the step of producing the laminated body 2, the embossing step, and the calendar step. Unlike the calendar process, the nip process is not intended to compress the laminate or the laminate. Therefore, in general, the linear pressure in the nip process is about 1.5 N / mm, which is smaller than the linear pressure in the calendar process.

The linear pressure is measured by the following method.
<Measurement method of linear pressure>
A pressure measurement film (manufactured by FUJIFILM Corporation, prescale) is introduced between a pair of rolls used in the calendar process or the nip process. Compare the color of the pressure measurement film with the standard color sample and read the linear pressure. If the color of the pressure measurement film is the upper limit of the standard color sample, select a pressure measurement film with a high measurable pressure range and perform the measurement again.

The raw material resins for producing the spunbond layer 10 and the melt blow layer 20 include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate; polyamides such as nylon 6 and nylon 66; polyacrylic acid and alkyl methacrylates. , Polyvinyl chloride, polyvinylidene chloride, polylactic acid, polyurethane, SIS, SEPS and the like, and one of these can be used alone or in combination of two or more.
The raw material resin for producing the spunbond layer 10 and the raw material resin for producing the melt blow layer 20 may be the same or different.

Examples of the cross-sectional shape of the spunbond fiber 11 and the melt blow fiber 21 include a circle, a triangle, a quadrangle, a polygon of a pentagon or more, a star, and the like, and among these, a circle is preferable. Here, the circle includes not only a perfect circle but also an ellipse. The cross-sectional shape of the spunbond fiber 11 and the cross-sectional shape of the melt blow fiber 21 may be the same or different.

In the manufacturing method of the above-described embodiment, as shown in FIG. 6, after the laminated body 2A in which the spunbond layer 10 and the melt blow layer 20 are laminated in this order is manufactured, the span is spanned on the melt blow layer 20 in the laminated body 2A. The bond fibers 11 are directly deposited to form the spunbond layer 10, and the laminate 2 to be embossed is manufactured. Therefore, the manufactured laminated nonwoven fabric 1 has an embossed portion as an embossed portion that bonds between the melt blow layer 20 and the spunbond layers 10 laminated on both sides of the melt blow layer 20, while the melt blow layer 20 or span. It does not have an in-layer embossed portion formed by pressurizing and compressing only the bond layer 10. That is, the laminated nonwoven fabric 1 includes only an embossed portion that is bonded between the melt blow layer 20 and the spunbond layer 10 laminated on one side or both sides of the melt blow layer 20.

Explaining the in-layer embossing portion, a spunbonded nonwoven fabric is usually produced by spinning spunbond fibers to form a spunbond layer, and then embossing the spunbond layer, usually heat embossing. .. Therefore, the spunbond layer usually has an in-layer embossed portion that bonds the fibers in the spunbond layer.
The laminated nonwoven fabric of the present invention does not have such an in-layer embossed portion, but only the embossed portion that is bonded between the melt blow layer 20 and the spunbond layer 10 located on one side or both sides of the melt blow layer 20. It is preferable to have the above from the viewpoint of maintaining excellent flexibility as a non-woven fabric.

The method for producing a laminated non-woven fabric having only an embossed portion that is bonded between the melt blow layer 20 and the spunbond layer 10 is not limited to the above-described embodiment, and may be, for example, the following method. First, after forming the melt blow layer 20, spunbond fibers 11 are directly deposited on the melt blow layer 20 to form a spunbond layer 10, and the melt blow layer 20 and the spunbond layer 10 form a laminate 2A in this order. To manufacture. Next, the manufactured laminate 2A is turned over. After that, the spunbond layer 10 is formed on the melt blow layer 20 in the laminated body 2A, and the subsequent steps are performed in the same manner as in the above-described embodiment to manufacture the laminated nonwoven fabric 1.
As described above, in the step of producing the laminate, after forming one of the melt blow layer and the spunbond layer, the fibers for forming the other layer are directly formed on the one layer. From the viewpoint of productivity, it is preferable to include a step of depositing to form the other layer.

Although the laminated nonwoven fabric of the present invention has been described above based on a preferred embodiment thereof, the laminated nonwoven fabric of the present invention is not limited to the above-described embodiment.
For example, in the laminated nonwoven fabric 1 of the above-described embodiment, the spunbond layers 10 are laminated on both sides of the melt blow layer 20, but the spunbond layer 10 may be laminated on only one side of the melt blow layer 20.
Further, in the manufacturing method of the above-described embodiment, the spunbond layer 10, the melt blow layer 20, and the spunbond layer 10 are formed in this order to form the laminated body 2 having a three-layer structure, but the last spunbond layer is formed. The embossing step and the calendar step may be performed on the spunbond-melt blow laminate 2A without forming the 10. In this case, a laminated non-woven fabric in which the span bond layer 10 is laminated on one side of the melt blow layer 20 is manufactured. The spunbond-melt blow laminate 2A may be manufactured by directly depositing the melt blow fibers 21 on the spun bond layer 10 after forming the spun bond layer 10 to form the melt blow layer 20. After forming 20, the spunbond fiber 11 may be directly deposited on the melt blow layer 20 to form the spunbond layer 10.

Further, in the above-described embodiment, the span bond layer 10 and the melt blow layer 20 are formed on the same production line, but instead, the span bond layer 10 and the melt blow layer 20 are formed on another production line. May be. Specifically, the melt blow fibers 21 may be deposited in a web shape on the spunbond layer 10 prepared in advance on another production line to form the melt blow layer 20. Further, the span bond layer 10 and the melt blow layer 20 may be prepared in advance on different production lines, and the span bond layer 10 and the melt blow layer 20 may be laminated to form the laminated body 2. Further, the laminated body 2 in which the spunbond layer 10 is laminated on only one side of the melt blow layer 20 is subjected to calendar processing, and then the spunbond layer 10 is laminated on the opposite side surface of the laminated body to manufacture a laminated non-woven fabric having a three-layer structure. You may.

A preferred embodiment of the method for producing an absorbent article of the present invention includes a step of laminating the surface material 32, the absorber 34, and the laminated non-woven fabric 1 in this order in the thickness direction. The laminated nonwoven fabric 1 is manufactured by the method for producing a laminated nonwoven fabric of the present invention. Further, the laminated nonwoven fabric 1 is arranged so that the spunbond layer 10 is located on the surface opposite to the surface side facing the absorber 34 side. In this laminating step, an absorbent article in which the surface material 32, the absorber 34, and the laminated non-woven fabric 1 are laminated in this order from the skin facing surface side to the non-skin facing surface side may be finally produced. The order in which the surface material 32, the absorber 34, and the laminated non-woven fabric 1 are laminated is not particularly limited. For example, the laminated non-woven fabric 1 may be laminated after laminating the surface material 32 and the absorber 34, or the surface material 32 may be laminated after laminating the absorber 34 and the laminated non-woven fabric 1, and the surface material 32 and the absorber may be laminated. 34 and the laminated non-woven fabric 13 may be laminated at the same time.

Hereinafter, the present invention will be described in more detail based on the examples, but the present invention is not limited to the following examples.

(Example 1)
After forming the spunbond layer (S), melt blow fibers were directly deposited on the spunbond layer (S) to form the melt blow layer (M). Then, the spunbond fibers were directly deposited on the formed melt blow layer (M) to form the spunbond layer (S). In this way, a laminate in which the spunbond layer (S), the melt blow layer (M), and the spunbond layer (S) were laminated in this order was produced. Next, the laminated body was embossed and then calendered to obtain the laminated non-woven fabric of Example 1. The laminated nonwoven fabric of Example 1 does not have an in-layer embossed portion, but has only an embossed portion that bonds between the melt blow layer and the spunbond layers laminated on both sides of the melt blow layer. There is. The two spunbond layers are all composed of fibers made of polypropylene resin, and the melt blow layer is made of fibers made of polypropylene resin. The linear pressure when the spunbond layer is subjected to calendar processing and the dimensions of each part of Example 1 are as shown in Table 1.

(Examples 2 to 5)
A laminated non-woven fabric was produced in the same manner as in Example 1 except that the linear pressure when the calendering process was performed was changed as shown in Table 1. The laminated nonwoven fabrics of Examples 2 to 6 do not have an in-layer embossed portion, but have only an embossed portion that is bonded between the melt blow layer and the spunbond layers laminated on both sides of the melt blow layer. doing.
(Example 6)
A laminated non-woven fabric was produced in the same manner as in Example 1 except that the basis weight of the non-woven fabric constituting the spunbond layer and the linear pressure when calendered were changed as shown in Table 1. The laminated nonwoven fabric of Example 6 does not have an in-layer embossed portion, but has only an embossed portion that is bonded between the melt blow layer and the spunbond layers laminated on both sides of the melt blow layer. There is.

(Example 7)
A laminated non-woven fabric was produced in the same manner as in Example 1 except that the linear pressure when calendering was applied and the fiber diameter of the melt blow fiber were changed as shown in Table 2. The laminated nonwoven fabric of Example 7 does not have an in-layer embossed portion, but has only an embossed portion that bonds between the melt blow layer and the spunbond layers laminated on both sides of the melt blow layer. There is.

(Comparative Example 1)
The melt-blow non-woven fabric was subjected to calendar processing to produce the melt-blow non-woven fabric of Comparative Example 1. The dimensions of each part of the melt-blown non-woven fabric of Comparative Example 1 are as shown in Table 1.
(Comparative Example 2)
The melt-blown nonwoven fabric of Comparative Example 2 was produced in the same manner as in Comparative Example 1 except that the calendering process was not performed. The dimensions of each part of the melt-blown non-woven fabric of Comparative Example 2 are as shown in Table 1.
(Comparative Example 3)
The laminated non-woven fabric of Comparative Example 3 was produced in the same manner as in Example 1 except that the calendering process was not performed.
(Comparative Examples 4, 6 and 8)
Melt-blow non-woven fabrics of Comparative Examples 4, 6 and 8 were produced in the same manner as in Comparative Example 1 except that the linear pressure when calendering was applied and the fiber diameter of the melt-blow fiber were changed as shown in Table 1.

(Comparative Example 5)
The laminated non-woven fabric of Comparative Example 5 was produced in the same manner as in Example 1 except that the linear pressure when calendering was performed and the fiber diameter of the melt blow fiber were changed as shown in Table 1.
(Comparative Example 7)
The laminated non-woven fabric of Comparative Example 7 was produced in the same manner as in Example 1 except that the fiber diameter of the melt blow fiber was changed as shown in Table 1.
(Comparative Example 9)
The laminated non-woven fabric of Comparative Example 9 was produced in the same manner as in Example 1 except that the linear pressure when calendered was changed as shown in Table 1.

The water pressure resistance of the nonwoven fabrics obtained in Examples 1 to 7 and Comparative Examples 1 to 9 was measured by the above-mentioned method, and the touch was evaluated by the following method. The measurement results of water pressure resistance and the evaluation results of the touch are as shown in Table 1.
<Evaluation method for touch>
Using a KES compression tester (KES FB-3 manufactured by Kato Tech Co., Ltd.), the laminated non-woven fabric is compressed to 5 kPa in normal mode except that the terminal speed is set to 0.1 mm / s, and the compression rigidity is high. LC was measured. The closer the value of LC is to 1, the harder it is, and the smaller the value, the better the feel.

As shown in Table 1, the laminated non-woven fabrics of Examples 1 to 7 have a water pressure resistance of 1600 mmAq. As described above, the water pressure resistance is significantly improved as compared with the laminated non-woven fabric of Comparative Example 3 which has not been calendered and the single-layer melt-blown non-woven fabric of Comparative Examples 1, 2, 4, 6 and 8.
The laminated non-woven fabric of Comparative Example 3 which was not calendered had a ratio of t _max / t _min of 1.3, and the laminated non-woven fabric of Comparative Example 9 which had been calendered under low linear pressure had a ratio of t _max / t. _{While the min} is 2.0, the ratio t _max / t _min of the laminated nonwoven fabrics of Examples 1 to 6 is more than 2, which is considered to contribute to the improvement of the water pressure resistance of the laminated nonwoven fabric of the present invention. Be done.
Further, the filling rate of the laminated non-woven fabric of Comparative Example 3 which has not been subjected to calendering is 6.7, whereas the filling rate of the laminated non-woven fabric of Examples 1 to 6 is 10 or more, which is the lamination of the present invention. It is considered that this contributes to the improvement of the water pressure resistance of the non-woven fabric.

From the comparison between Comparative Example 5 and Comparative Example 6, the comparison between Comparative Example 7 and Comparative Example 8, and the comparison between Example 7 and Comparative Example 4, when the fiber diameter of the melt blow fiber was less than 1 μm, the spunbond layer was used. It can be seen that the effect of improving the water pressure resistance is recognized by laminating the melt blow layer and performing calendar processing. Further, in Comparative Example 7, Comparative Example 5, Example 7, and Example 1, the fibers of the melt blow layer had fiber diameters of 1.1 μm, 1.0 μm, 0.9 μm, and 0.8 μm in this order. When the diameter is less than 1, the water pressure resistance sharply improves.
From these results, in order for the laminated nonwoven fabric of the present invention to exhibit high water pressure resistance, the fiber diameter of the melt blow fiber must be less than 1 μm and at least one of the above conditions (1) and (2) must be satisfied. It turns out to be important.

Looking at the evaluation results of the filling rate and the touch of the laminated non-woven fabric of Examples 1 to 4, it is recognized that the water pressure resistance tends to improve as the filling rate increases. From the viewpoint of achieving both water pressure and touch, it is preferable to suppress the filling rate of the laminated non-woven fabric to 35% or less so as to obtain a good feel equivalent to that of the laminated non-woven fabric of Comparative Example 3 which has not been subjected to calendar processing. ..

Further, in the laminated non-woven fabric of Comparative Example 3 which was not subjected to the calendar processing, the ratio of the maximum fiber width to the minimum fiber width of the spunbond fibers was 1.1, whereas the ratio of the maximum fiber width to the minimum fiber width was 1.1, whereas the calendar processed Examples 1 to 7 were performed. In the laminated non-woven fabric of Comparative Example 9, the ratio of the maximum fiber width to the minimum fiber width (maximum fiber diameter / minimum fiber diameter) of the spunbond fibers is 1.4 or more and 2.2 or less. This indicates that the laminated non-woven fabrics of Examples 1 to 7 and Comparative Example 9 have a region in which the spunbond fibers are largely flattened by the calendar processing. Further, the laminated nonwoven fabrics of Examples 1 to 7 have a larger ratio of the maximum fiber width to the minimum fiber width of the spunbonded fibers than the laminated nonwoven fabric of Comparative Example 9 in which the calendar processing is performed under the condition of low linear pressure. It has become. In the laminated non-woven fabrics of Examples 1 to 7, the surface of the melt blow layer is covered with a wider area by performing calendar processing with sufficient linear pressure so that there is a region in which the spunbond fibers are largely flattened. It is thought that the ability to do so also contributed to the improvement of water pressure resistance.

As shown in Table 1, in Examples 1 to 7, the cross-sectional shape of the melt blow fibers is partially elliptical, and the cross-sectional shape of the spunbond fibers is also elliptical. The partially elliptical shape (denoted as "partially elliptical" in Table 1) means that the cross-sectional shape has a perfect circle or a substantially perfect circular portion and an elliptical portion. On the other hand, in Comparative Example 3, the cross-sectional shape of the melt blow fiber is a perfect circle, and the cross-sectional shape of the spunbond fiber is a substantially perfect circle. This indicates that the fibers of each layer were deformed into an elliptical shape by the calendar processing. As a result, the spunbond fiber can cover the surface of the melt blow layer in a wider area, which is also considered to have contributed to the improvement of the water pressure resistance.

(Examples 8 to 11)
A laminated non-woven fabric was produced in the same manner as in Example 1 except that the linear pressure when the calendering was applied and the fiber diameter of the spunbond fibers before the calendering were changed as shown in Table 2. The laminated nonwoven fabrics of Examples 8 to 11 do not have an in-layer embossed portion, but have only an embossed portion that is bonded between the melt blow layer and the spunbond layers laminated on both sides of the melt blow layer. doing.
(Comparative Example 9)
The laminated non-woven fabric of Comparative Example 9 was produced in the same manner as in Example 1 except that the linear pressure for calendering was changed as shown in Table 2.

The water pressure resistance of Examples 8 to 11 and Comparative Example 9 was measured by the above method. In addition, the texture of Examples and Comparative Examples was evaluated by the above-mentioned method. The measurement results of water pressure resistance and the evaluation results of the touch are as shown in Table 2.

Comparing the results of Example 8 and Example 9, Example 8 has a higher linear pressure during calendar processing than Example 8, but Example 8 has a higher linear pressure than Example 9. Water pressure resistance is improved. Examining the cause of this, in Example 8, since the spunbond fibers are thinner than in Example 9, the fiber density of the spunbond layer is high and the distance between the fibers is narrow, so that the interval for restraining the melt blow fibers is short. It is considered that the melt blow fibers are more fixed. From the viewpoint of improving the water pressure resistance, the fiber diameter of the spunbond fiber is preferably 35 μm or less.

According to the laminated nonwoven fabric of the present invention, it is possible to provide a laminated nonwoven fabric having improved water pressure resistance.
According to the method for producing a laminated nonwoven fabric of the present invention, a laminated nonwoven fabric having improved water pressure resistance can be produced.

Claims (30)

1. A laminated non-woven fabric having a melt blow layer and a spunbond layer laminated on one side or both sides of the melt blow layer.
   The fibers constituting the melt blow layer have a fiber diameter of less than 1 μm.
   A laminated non-woven fabric for absorbent articles that satisfies at least one of the following (1) and (2).
   (1) The ratio of the maximum thickness t _max to the minimum thickness t _min of the melt blow layer, t _max / t _min, is more than 2.
   (2) The filling rate of the laminated non-woven fabric is more than 7.7%.
2. A laminated non-woven fabric having a melt blow layer and a spunbond layer laminated on one side or both sides of the melt blow layer.
   The fibers constituting the melt blow layer have a fiber diameter of less than 1 μm.
   A laminated non-woven fabric for absorbent articles, wherein t _max / t _min, which is a ratio of the maximum thickness t _max to the minimum thickness t _min of the melt blow layer, is more than 2.
3. A laminated non-woven fabric having a melt blow layer and a spunbond layer laminated on one side or both sides of the melt blow layer.
   The fibers constituting the melt blow layer have a fiber diameter of less than 1 μm.
   A laminated non-woven fabric for absorbent articles having a filling rate of more than 7.7%.
4. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 3, wherein the fiber diameter of the fibers constituting the spunbond layer is larger than the fiber diameter of the fibers constituting the melt blow layer.
5. The laminated non-woven fabric for absorbent articles according to any one of claims 1 to 4, wherein the fiber constituting the spunbond layer has a fiber aspect ratio of more than 1.2 in the cross section of the fiber.
6. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 5, wherein the fiber diameter of the fibers constituting the melt blow layer is 0.1 μm or more and less than 1 μm.
7. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 6, wherein the fiber diameter of the fibers constituting the melt blow layer is 0.1 μm or more and 0.85 μm or less.
8. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 7, wherein t _max / t _min , which is a ratio of the maximum thickness t _max to the minimum thickness t _min of the melt blow layer, is more than 2 and 14 or less. ..
9. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 8, wherein t _max / t _min , which is a ratio of the maximum thickness t _max to the minimum thickness t _min of the melt blow layer, is 3 or more and 10 or less.
10. The absorbent article according to any one of claims 1 to 9, wherein the filling rate of the laminated non-woven fabric is more than 7.7% and 35% or less, preferably 10% or more, and more preferably 14% or more. For laminated non-woven fabric.
11. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 10, wherein the fibers constituting the spunbond layer have a fiber aspect ratio of more than 1.2 and 2.5 or less in the cross section of the fibers. ..
12. Any of claims 1 to 11, wherein the fibers constituting the spunbond layer have a ratio of the maximum fiber width to the minimum fiber width (maximum fiber diameter / minimum fiber diameter) of more than 1.1 and 2.5 or less. The laminated non-woven fabric for absorbent articles according to item 1.
13. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 12, wherein the laminated nonwoven fabric has a filling rate of 35% or less, preferably 30% or less, and more preferably 25% or less.
14. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 13, wherein the filling ratio of the laminated nonwoven fabric is 14% or more and 25% or less.
15. Among the fibers constituting the spunbond layer, the proportion of fibers whose long axis in the cross section of the fiber is closer to the direction parallel to the plane of the laminated non-woven fabric than the short axis is 75% or more and 100% or less, preferably. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 14, which is more than 75% and 100% or less, more preferably 80% or more and 100% or less, and further preferably 85% or more and 100% or less.
16. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 15, wherein the filling rate of the melt blow layer is more than 4.1% and 11% or less.
17. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 16, wherein the filling rate of the melt blow layer is 6% or more and 9% or less.
18. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 17, wherein the fiber diameter of the fibers constituting the spunbond layer is 16 μm or more and 35 μm or less.
19. The water pressure resistance of the laminated non-woven fabric is 1600 mmAq. More than 5000 mm Aq. The laminated nonwoven fabric for absorbent articles according to any one of claims 1 to 18, which is as follows.
20. The laminated non-woven fabric comprises only an embossed portion that is bonded between the melt blow layer and the spunbond layer laminated on one side or both sides of the melt blow layer, according to any one of claims 1 to 19. The laminated nonwoven fabric for absorbent articles described.
21. The absorption according to any one of claims 1 to 20, wherein either one or both of the cross-sectional shape of the fibers constituting the spunbond layer and the cross-sectional shape of the fibers constituting the melt blow layer are circular. Laminated non-woven fabric for sex goods.
22. It has a skin facing side and a non-skin facing side,
    A surface material and an absorber arranged on the non-skin facing surface side of the surface material are provided.
    The laminated non-woven fabric for absorbent articles according to any one of claims 1 to 21 is arranged on the non-skin facing surface side of the absorber.
    The laminated non-woven fabric is an absorbent article in which the span bond layer is arranged toward the non-skin facing surface side.
23. A laminated body including a step of forming a spunbond layer by a spunbond method and a step of forming a meltblow layer by a meltblow method, and having the meltblow layer and a spunbond layer laminated on one side or both sides of the meltblow layer. Manufacturing process and
    An embossing process for embossing the laminate, and
    A method for producing a laminated non-woven fabric for an absorbent article, which comprises a calendar step of applying a calendar process to the laminated body.
24. The method for producing a laminated non-woven fabric for an absorbent article according to claim 23, which has the calendar step after the embossing step.
25. The method for producing a laminated non-woven fabric for an absorbent article according to claim 23 or 24, wherein the calendar processing is performed at a linear pressure of 2 N / mm or more and 40 N / mm or less in the calendar step.
26. The method for producing a laminated non-woven fabric for an absorbent article according to any one of claims 23 to 25, wherein the linear pressure in the calendar step is 10 N / mm or more and 25 N / mm or less.
27. In the step of producing the laminate, after forming one of the melt blow layer and the spunbond layer, fibers forming the other layer are directly deposited on the one layer. The method for producing a laminated nonwoven fabric for an absorbent article according to any one of claims 23 to 26, which comprises a step of forming the other layer.
28. The method for producing a laminated non-woven fabric for absorbent articles according to any one of claims 23 to 27, wherein the anvil roll used for the calendar processing has a smooth surface.
29. The production of the laminated nonwoven fabric for absorbent articles according to any one of claims 23 to 28, wherein the calendar step is performed at a temperature lower than the melting point of the fibers contained in the laminate, that is, the spunbond fibers and the melt blow fibers. Method.
30. It has a step of laminating the surface material, the absorber, and the laminated non-woven fabric in this order in the thickness direction.
    The laminated nonwoven fabric is manufactured by the method for producing a laminated nonwoven fabric for absorbent articles according to any one of claims 23 to 30, and the laminated nonwoven fabric is on the side opposite to the surface side facing the absorber side. A method for producing an absorbent article, which is laminated so that a spunbond layer is located on a surface.

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