RU2733362C1 - Hot air-bonded non-woven material for absorbent product - Google Patents

Abstract

FIELD: nonwoven materials.

SUBSTANCE: disclosed is hot air-bonded non-woven material for an absorbent product, in which two or more fibrous layers are laid on each other, comprising at least one fibrous layer comprising thermoplastic fibers and a portion with fiber accumulation.

EFFECT: disclosed is hot air-bonded non-woven material.

13 cl, 3 dwg, 2 tbl

Description

[FIELD OF THE INVENTION

[0001]

The present invention relates to a hot air bonded nonwoven fabric for an absorbent article.

BACKGROUND OF THE INVENTION

[0002]

The hot air bonded nonwoven fabric is formed by thermally fusing the fiber crossover points with each other by blowing hot air using an air passing method, thereby allowing the hot air bonded nonwoven fabric to thicken relatively easily and transform into a very good texture. Such hot air bonded nonwovens are often used as components in absorbent articles. Various options have been proposed in the past for such a hot air bonded nonwoven material for use in absorbent articles.

For example, Patent Document 1 discloses a hot air bonded nonwoven fabric in which the difference in thickness at a low-fiber location and a thickness at a non-low-fiber location is adjusted to 1 mm or less under a pressure of 7.64 kPa to ensuring the aesthetic effect of the pattern without negatively affecting the texture. The use of calendering for a pre-fabricated nonwoven fabric obtained by a hot air blown treatment has been described as a method for manufacturing this hot air bonded nonwoven fabric. Patent Document 2 discloses an absorbent article including a nonwoven fabric having thermoplastic synthetic fibers and organic cotton fibers. In this nonwoven fabric, organic cotton fibers are arranged to form a plurality of fiber clusters. The organic cotton fibers are held in the nonwoven by entangling the fibers without thermal fusion.

In Patent Document 3, in order to improve the texture of the nonwoven fabric, it is proposed to perform the processing of the finished nonwoven fabric by applying pressure thereto between two rolls at a certain line pressure and a certain temperature.

Patent Document 4 describes a processing method in which a fibrous sheet wound in a roll is unwound and hot air is blown using an air-passing method to apply calendering to a given sheet at a certain line pressure.

LIST OF LINKS

PATENT DOCUMENTS

[0003]

Patent Document 1: JP-A-2013-151774 (“JP-A” means Japan's Unexamined Published Patent Application)

Patent Document 2: JP-A-2017-202265

Patent Document 3: JP-A-60-126365

Patent Document 4: JP-A-2006-299480

SUMMARY OF THE INVENTION

[0004]

The present invention provides a hot air bonded nonwoven fabric for an absorbent article in which two or more fibrous layers are superimposed and which contains at least one fibrous layer containing thermoplastic fibers and a fiber aggregate portion.

[0005]

In addition, the present invention provides a method for manufacturing a hot air bonded nonwoven fabric for an absorbent article, comprising:

a loosening step in which a loosening treatment is applied to the thermoplastic fibers a plurality of times to form a web;

a step in which a plurality of single-layer webs obtained in the opening step are stacked on top of each other to form a multi-layer web, and hot air treatment by passing air is applied to the multi-layer web to obtain a hot-air bonded nonwoven fabric; and

a calendering step in which calendering is applied to one or more of sheets selected from a single-layer web, a multi-layer web, and a hot air bonded nonwoven fabric using a pair of calender rolls.

[0006]

Other and additional objects, features and advantages of the invention will become more fully apparent from the description below with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

[0007]

[Fig. 1]

1 is a cross-sectional view schematically showing one preferred embodiment of a hot air bonded nonwoven fabric for an absorbent article according to the present invention.

[Fig.2]

Fig. 2 is a schematic configuration view showing one preferred embodiment of a method for manufacturing a nonwoven fabric and a manufacturing device for carrying out the method according to the present invention.

[Fig. 3]

Fig. 3 is a schematic configuration view showing another preferred embodiment of a heat treating apparatus for performing an air-passing step in this embodiment.

DESCRIPTION OF IMPLEMENTATION OPTIONS

[0008]

The present invention relates to a hot air bonded nonwoven fabric for an absorbent article that is formed as a fabric having a very good bulk and soft texture and made with a pattern.

[0009]

In the step of making the hot air bonded nonwoven fabric, while loosening the fibers to form a web, the fibers entangle with each other, whereby fiber clumps are formed locally randomly. Of particular interest is that the aforementioned fiber clumps occur more readily as the diameter of the fibers decreases. If this fiber bundle is directly exposed to the hot air blowing step, the fiber bundle hardens due to the thermal fusion of the fibers.

Meanwhile, as described in Patent Literatures 1, 3 and 4 discussed above, up to now, in practice, the finished nonwoven fabric has been calendered to reduce the hardness. However, calendering is a treatment in which a hot air bonded nonwoven is placed between two rolls to apply pressure thereto, and after pressure is applied to the hot air bonded nonwoven, its thickness is reduced, therefore, there is a possibility to improve bulk. Even if the hot air treatment is carried out after calendering the nonwoven fabric as described in Patent Literatures 1, 3 and 4 above, there is a limitation in regaining the thickness of the once collapsed nonwoven fabric, so there is still further room for improvement in this regard. In this regard, it should be noted that in the above-mentioned patent literature 3 there are no proposals related to the restoration of bulk.

It is highly desirable to provide both sufficient bulk and soft texture of the hot air-bonded nonwoven fabric for absorbent articles to provide a material excellent in absorbency and cushioning and the like of an absorbent article.

[0010]

In contrast, the hot air bonded nonwoven fabric for an absorbent article of the present invention is formed as a fabric that has a very good bulk and soft texture and is patterned. In addition, according to the manufacturing method of the present invention, the above hot air bonded nonwoven fabric for an absorbent article can be manufactured with a high degree of perfection.

[0011]

Hereinafter, the hot air bonded nonwoven fabric for an absorbent article according to the present invention will be described with reference to the drawings.

The hot air bonded nonwoven fabric for an absorbent article of the present invention can be applied to various absorbent articles worn on the body to absorb body fluid, and can be applied to various components such as a topsheet in an absorbent article.

[0012]

In the present invention, unless otherwise indicated, the side in contact with the human body is referred to as the side of the surface facing the skin, the side of the surface in contact with the skin or the side of the surface, and the side opposite to it is referred to as the side of the surface, not the skin-facing side, the non-skin-contact side, or the back / back side.

The term “hot air bonded nonwoven fabric” in the present invention means a fabric in which the heat-fusing fibers are heat-fused to each other at intersections and bonded. The air flow method is used to make this nonwoven fabric. The air-passing method means a method in which hot air is blown onto a fibrous web containing heat-meltable fibers by a passing method to fuse the intersections between the webs with each other, whereby a nonwoven fabric is formed.

[0013]

The hot air bonded nonwoven fabric for an absorbent article according to the present invention is a hot air bonded nonwoven fabric in which two or more fibrous layers are superimposed on each other. The fibrous layers to be stacked can be two layers or three or more layers. The hot air bonded nonwoven fabric for an absorbent article according to the present invention has two or more layers, and the hot air bonded nonwoven fabric can be formed as a bulkier nonwoven fabric that goes beyond manufacturing limitations compared to the case where the nonwoven fabric is formed by one layer.

[0014]

1 shows, as a preferred embodiment of a hot air bonded nonwoven fabric for an absorbent article according to the present invention, a hot air bonded nonwoven fabric 10 for an absorbent article in which two fibrous layers (fibrous layer 1 and fibrous layer 2) are superimposed (in hereinafter referred to simply as nonwoven fabric 10). The fibrous layer 1 and the fibrous layer 2 include heat-fusing fibers, and the contact surfaces of both layers are bonded over the entire area by fusing the heat-fusion fibers with each other. Therefore, the nonwoven fabric 10 does not have a zone in which the fibrous layer 1 and the fibrous layer 2 are separated from each other. That is, the nonwoven fabric 10 is one sheet-like member in which the two layers described above are combined into one piece.

[0015]

The nonwoven fabric of the present invention can have various surface shapes, such as an uneven surface. However, in the nonwoven fabric 10 of this embodiment shown in FIG. 1, both surfaces 10A and 10B (the surface of the fibrous layer 1 and the surface of the fibrous layer 2) are preferably flat. The nonwoven fabric 10 is a multilayer fabric of many fibrous layers, and both surfaces have a flat shape, whereby a very good fabric is obtained, both having a smooth surface and giving a cushioning feeling. The term "flat shape" means a shape in which the difference in thickness in the concave portion and the convex portion on the surface of the nonwoven fabric is within 1 mm. Specifically, the nonwoven is cut in the thickness direction using a razor blade to take a cross-sectional photograph using a microscope (VHX-900 manufactured by Keyence Corporation). In the photograph, the thickness of the portion in which the upper surface of the nonwoven fabric is located at the highest, namely the convex portion, and the thickness of the portion in which the upper surface of the nonwoven fabric is located the lowest, namely the concave portion, are measured to calculate the given thickness difference, whereby the difference in thickness is determined. The average of the three points is taken as the difference in thickness.

[0016]

The nonwoven fabric 10 has at least one fibrous layer 8 containing a bundle portion 7. Hereinafter, the fibrous layer 8 containing the aggregate portion 7 is referred to as the fibrous layer 8. In Fig. 1, a clumping layer 8 is located in a fibrous layer 1.

[0017]

In the present invention, the term “fiber mass portion” means the part of a knot (fiber accumulation) formed by entanglement of fibers in the fibrous layer. A part with an accumulation of fibers can be recognized as an accumulation (in the form of a granule) in which the density of the fibers is higher than in the peripheral part in the same fibrous layer, and the concentration (degree of intensity) of the color (mainly white) of the fibers is visually greater than in peripheral part. The shape of the clumped portion is not particularly limited. In the present invention, it is preferable that the clumping portion is formed with a collapsed shape in which the fibers are collapsed in the thickness direction of the nonwoven fabric when viewed in a cross section of the nonwoven fabric taken in the thickness direction, and the surface of the clumping portion on the surface of the nonwoven fabric has smooth structure. Thus, the surface of the nonwoven fabric corresponding to the location where the fiber clumping portion 7 is present is smoothed, whereby the surface texture of the nonwoven fabric 10 is felt to be excellent.

[0018]

The term "clump layer 8" above means a layer containing one or more clump portions. The clumped layer 8 is optionally completely filled with the clumped portions 7 and is preferably configured such that the clumped portions 7 are dispersed.

[0019]

The clumped layer 8 is not limited to the case in which the clumped layer 8 is present only in the fibrous layer 1 as shown in FIG. 1, and may be present in the fibrous layer 2 instead of the fibrous layer 1, or in both layers. For reasons of soft texture, the fiber clump layer 8 is preferably present in either one of the two layers. For reasons of enhancing the visual effect of the pattern created by the fiber portions 7 in the plan view of the nonwoven fabric 10, the fiber layers 8 are preferably present in both layers. Thus, from the pattern formed by the parts 7 with an accumulation of fibers, it can be seen that they are dispersed not only in the direction in the plane of the nonwoven fabric 10, but also in the direction of its thickness, and in the presence of this pattern on the side of the lower layer, it can be seen that the concentration of parts 7 with an accumulation of fibers visible in the thickness direction changes downward, and a pattern on the thickness of the material can be seen. When the clumping layers 8 are present in both of the fibrous layer 1 and the fibrous layer 2, the clumping portion 7 in the fibrous layer 1 and the clumping portion 7 in the fibrous layer 2 are preferably arranged so that they do not overlap in the thickness direction. In addition, the clumping layer 8 can be fully or partially located in the fibrous layer (fibrous layer 1 or fibrous layer 2) in which the clumping layer 8 is located.

[0020]

As mentioned above, the nonwoven fabric 10 is formed by fusing and bonding fibers to each other at the contact surface of the layers over the entire area in which the fibrous layer 1 and the fibrous layer 2 contact. Thus, even if the nonwoven fabric 10 contains an accumulated fiber layer 8, containing the bundled fiber portion 7, the nonwoven fabric 10 as a whole, in which a plurality of fibrous layers are integrated into one at the contact surfaces of the layers, feels like a thick fabric having very good bulk and soft texture. In this case, as seen in the plan view of the nonwoven fabric 10, the nonwoven fabric 10 is formed as a fabric made with a pattern created by the difference due to varying color concentration between the portions with fiber aggregates and the portions without fibers. The nonwoven fabric 10 is formed in the form of a fabric made with an aesthetic characteristics by the pattern formed by these fiber portions 7, in particular the pattern formed by the fiber portion 7 in which the thickness is reduced.

[0021]

The nonwoven fabric 10 of this embodiment preferably has fine fibers having a fiber diameter of 1 dtex or more and 2.2 dtex or less, and thick fibers having a fiber diameter that is larger than that of the fine fibers. Thus, both an improvement in the soft texture of the nonwoven fabric due to thin fibers and an improvement in bulk due to thick fibers can be achieved. In addition, the nonwoven fabric 10 has thick fibers, which can also help to increase the ability of the nonwoven fabric 10 to recover the thickness of the nonwoven fabric after pressure is applied, and this situation is preferable.

[0022]

In addition, the clumped layer 8 preferably includes the fine fibers described above. In this case, the fine fibers described above may be contained in the clumping portion 7 or may be contained in a portion other than the clumping portion 7. Thus, the hardness of the area around the bundled portion 7, felt on contact with the nonwoven fabric 10, is reduced by the presence of the fine fibers described above. In this case, in the nonwoven fabric 10, the fibrous layer 1 having the aggregate layer 8 including the fine fibers described above is preferably positioned closer to the skin-contacting surface side of the absorbent article.

[0023]

For reasons related to improving the soft texture of the nonwoven fabric 10, the fiber diameter of the fine fibers described above is more preferably 2 dtex or less, and even more preferably 1.5 dtex or less. For reasons related to card spinning when making a nonwoven fabric, the diameter of the fine fibers described above is more preferably 1 dtex or more, and even more preferably 1.2 dtex or more. In particular, the diameter of the fine fibers is preferably 1 dtex or more and 2 dtex or less, and more preferably 1.2 dtex or more and 1.5 dtex or less.

[0024]

For reasons related to improving the soft texture of the nonwoven fabric 10, the content of fine fibers described above in the filament layer 8 is preferably 50% or more, more preferably 80% by mass. or more, and even more preferably 100% by mass, in which case it is expressed as a mass fraction.

[0025]

The nonwoven fabric 10 of this embodiment preferably has at least one fibrous layer 9 not containing the bundled portion 7 (hereinafter referred to as the non-bundled layer 9) in addition to the bundled layer 8 mentioned above. For example, as shown in FIG. 1, specific examples include an embodiment in which the fibrous layer 1 is a clumped layer 8 and the fibrous layer 2 is a non-clumped layer 9.

[0026]

When the nonwoven fabric 10 has a clumped layer 8 and a non-clumped layer 9, it is preferable that the nonwoven fabric 10 has thick fibers having a fiber diameter of more than 2.2 dtex and 7 dtex or less, and thin fibers having a fiber diameter that less than the diameter of thick fibers. The diameter of the fine fibers is preferably in the range indicated above. Thus, both an improvement in the soft texture of the nonwoven fabric with fine fibers and an improvement in bulk with thick fibers can be achieved, while the thick fibers in the nonwoven fabric 10 can also contribute to an increase in the ability to recover the thickness of the nonwoven fabric after application of pressure, and such the situation is preferable.

[0027]

The fiber-free layer 9 preferably includes the thick fibers described above. The non-clumped layer 9 includes the thick fibers described above, and this configuration can provide an increase in bulk and provide a nonwoven fabric 10 with a springy feel. In this case, in the nonwoven fabric 10, the fibrous layer 2 having the non-clumped layer 9 including thick fibers is preferably located closer to the non-skin-contacting surface side of the absorbent article.

[0028]

For reasons of increasing the bulk of the nonwoven fabric 10 and improving its compressibility, the diameter of the thick fibers described above is more preferably greater than 2.2 dtex and even more preferably 4.4 dtex or more. For considerations related to the sensation of the side of the bundled layer, the diameter of the thick fibers described above is more preferably 5.5 dtex or less, and even more preferably 5 dtex or less. In particular, the diameter of the thick fibers is preferably more than 2.2 dtex and 5.5 dtex or less, and more preferably 4.4 dtex or more and 5 dtex or less.

[0029]

For reasons related to increasing the bulk of the nonwoven fabric 10 and increasing its compressibility, the content of thick fibers described above in the layer 9 without fiber aggregates is preferably 50% or more, more preferably 80% by mass. or more, and even more preferably 100% by mass, in which case it is expressed as a mass fraction.

[0030]

For reasons related to improving the soft texture of the nonwoven fabric 10, the content of thick fibers described above in the layer 8 with the accumulation of fibers is preferably 50 wt%. or less, more preferably 30% of the mass. or less, and even more preferably 10% of the mass. or less, while it is expressed as a mass fraction.

[0031]

(Method for measuring the diameter of fine fibers and thick fibers, method for determining the content of fine fibers in layer 8 with clumping and method for determining the content of thick fibers in layer 9 without clumping fibers)

At a randomly selected location of the nonwoven fabric, three areas on the side of the bundled layer and the surface side of the non-bundled layer are enlarged and examined at 100 times magnification using a scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.).

Fiber diameter: Measure the diameter of the fibers within an area of 1 mm ² . The measurement of the fiber diameter is performed at 20 points for each fiber differing from the other by one zone, and the average value is taken as the diameter of each fiber. In addition, the fluctuation range of the fiber diameter in the nonwoven fabric for an absorbent article is usually small and difficult to confirm even when observed using the scanning electron microscope described above. For example, the range of variation in fiber diameter is typically about 6% according to fiber specifications. Accordingly, if a value obtained by measuring diameters at 20 points and averaging the data is selected as described above, this value can be taken as the diameter of each fiber.

Fiber ratio: OHP film ( Overhead Projector Film ) is placed on the photograph within the 1 mm ^{2 area} previously enlarged and viewed, and then the plane is painted black. Image analysis data processing is performed on this sheet using image analysis software (NexusNewQube). Binarization is performed to determine the area. The area of each fiber is measured and the fraction obtained is taken as the relative content of each fiber.

[0032]

(Method of sampling the element to be measured)

When a component (for example, a surface material) to be measured is removed from an absorbent article to perform a measurement for evaluation in the measurement described above, a sample is obtained in the following manner. That is, when the component is attached to any other component by an adhesive or the like, the adhesive is cooled with liquid nitrogen to facilitate separation of the component. When the component is attached to any other component by fusion or the like, the component is removed by hand, or the fused portion is cut with a knife or the like to separate the component for measurement. This method is used in a similar way also in other measurement methods.

[0033]

In the nonwoven fabric 10, the average fiber diameter in the non-clustered layer 9 is preferably greater than the average fiber diameter in the clustered layer 8. Thus, the clumped layer 8 serves as a layer for improving the soft texture of the nonwoven fabric 10, and the non-clumping layer 9 serves as a layer for increasing the bulk of the nonwoven fabric 10 and increasing its rethickness. As a result, the clumped layer 8 and the non-clumped layer 9 can have a separation of functions in the laminate to form the nonwoven fabric 10, and both layers can interact in the thickness direction to further improve the overall feel of the nonwoven fabric 10. In this regard, it is preferable that the nonwoven fabric 10 has the fine fibers described above and the thick fibers described above, and that the filamentous layer 8 includes the fine fibers described above, since the effect described above can be more evident. For the same reasons, it is more preferable that the fiber-free layer 9 includes the thick fibers described above.

[0034]

For reasons related to the separation of functions described above, in a nonwoven fabric, the difference V3 (= V1 - V2) of the average fiber diameter V1 of the fibers of the non-clumped layer 9 and the average fiber diameter V2 of the clumped layer 8 is preferably greater than 0 dtex, more preferably 2.2 dtex or more, and even more preferably 3 dtex or more. In addition, for the same reasons stated above, the difference V3 is preferably 5.6 dtex or less, more preferably 4 dtex or less, and even more preferably 3.5 dtex or less. In particular, the difference V3 is preferably more than 0 dtex and 5.6 dtex or less, more preferably 2.2 dtex and 4 dtex or less, and even more preferably 3 dtex and 3.5 dtex or less.

[0035]

(Method for determining the average fiber diameter of layer 8 with aggregates and layer 9 without aggregates)

Fiber diameters and ratios determined based on the (Method for measuring the diameter of fine fibers and thick fibers, method for determining the content of fine fibers in layer 8 with clumping and method for determining the content of thick fibers in layer 9 without clumping fibers) described above , multiplied, and the sum of the resulting values is taken as the average fiber diameter of each layer.

[0036]

In the nonwoven fabric 10, the basis weight of the non-bundled layer 9 is preferably greater than the basis weight of the bundled layer 8. Thus, the non-fiberized layer 9 becomes more bulky than the fiberized layer 8, and the hardness of the fiberized portion 7 becomes more difficult to feel. The bulk of the layer 9 without aggregation of fibers serves to increase the springability of the nonwoven fabric 10 as a whole, while the load acting on the skin from the side of the aggregate part 7 can be further reduced when the layer 8 with aggregation of fibers is flattened in the thickness direction, for additional improving the good feeling. Effects as described above can be shown more clearly, when coupled with the difference in the surface density of the nonwoven material 10 has thin fibers described above, and thick fibers described above, and the layer 8 with the accumulation of fibers includes fine fibers described above, and therefore this situation is preferable. For the same reasons, it is more preferable that the fiber-free layer 9 includes the thick fibers described above. Preferably, the nonwoven fabric 10 has a larger average fiber diameter in the non-agglomerated layer than in the non-agglomerated layer 8.

[0037]

For reasons of springback performance and improving the overall feel of the nonwoven fabric as described above, the difference Y3 (= Y1 - Y2) of the basis weight Y1 of the non-clumped layer 9 and the basis weight Y2 of the clumped layer 8 is preferably greater than 0 g. / m ² , more preferably 3 g / m ² or more, and even more preferably 5 g / m ² or more. For reasons related to improving the good feel, the difference Y3 is preferably 20 g / m ² or less, more preferably 15 g / m ² or less, and even more preferably 10 g / m ² or less. In particular, the difference Y3 is preferably more than 0 g / m ² and 20 g / m ² or less, more preferably 3 g / m ² or more and 15 g / m ² or less, and even more preferably 5 g / m ² or more. and 10 g / m ² or less.

[0038]

(Method for determining areal density of layer 8 with fiber aggregation and layer 9 without fiber aggregation)

1) The value obtained by converting the weight of the nonwoven fabric to be measured into a value per m ² is taken as the total basis weight.

The weight (w) of the nonwoven fabric to be measured is measured, and then the value calculated by the equation below is taken as the total areal density (W).

W = (1000000 / LMD / LCD) w = 25w

LMD: Machine direction length of nonwoven fabric to be measured - 250mm

LCD: Length of the nonwoven fabric to be measured in the transverse direction is 160 mm

When it is not possible to take a sample with the dimensions shown above, when taking a sample from the product, the sample is cut with the dimensions with which the sample can be obtained, and the obtained data is converted to a value per m ² .

2) The basis weight of each layer: Each layer of nonwoven fabric to be measured is carefully peeled off, and the value obtained by converting the weight to a value per m ² is taken as the basis weight of each layer.

[Unit of measurement: Number of digits] g / m ² : Round the hundredths to the nearest tenth.

[Number of measurements]: The measurement is made at three points, and the average value is taken as each areal density.

[0039]

For reasons of providing a fabric with a very good bulk and soft texture and a good feel for a structure in which two or more fibrous layers are superimposed and combined, the basis weight of the nonwoven fabric 10 as a whole is preferably 15 g. / m ² or more, more preferably 18 g / m ² or more, and even more preferably 20 g / m ² or more. For reasons related to spinnability in manufacturing the nonwoven fabric, the basis weight of the nonwoven fabric 10 as a whole is preferably 40 g / m ² or less, more preferably 30 g / m ² or less, and even more preferably 25 g / m ² or less. In particular, the basis weight of the nonwoven fabric 10 as a whole is preferably 15 g / m ² or more and 40 g / m ² or less, more preferably 18 g / m ² or more and 30 g / m ² or less, and even more preferably 20 g / m ² or more and 25 g / m ² or less. Here, the basis weight of the nonwoven fabric 10 is generally determined according to the (Method for Determining Areal Density of the Clumped Layer 8 and the Non-Clumping Layer 9) above.

[0040]

With regard to such a nonwoven fabric 10, in the case where the thickness of the nonwoven fabric 10 measured at a pressure of 7.64 kPa at the location where the clumping portion 7 is located is taken as T1, and the thickness of the nonwoven fabric 10 measured under the same pressure in the place where the part 7 with an accumulation of fibers is not located is taken as T2, and the difference T3 of thicknesses, determined by the equation: T3 = T1 - T2, has a smaller value, it is more difficult to feel the hardness created by the part 7 with an accumulation of fibers. As a result, a bouncy feeling is easily created, accompanied by a bulky feeling provided by the stacking of a plurality of fibrous layers, and a soft textured feeling is easily created. For these reasons, the thickness difference T3 is preferably 0.4 mm or less, more preferably 0.3 mm or less, even more preferably 0.2 mm or less, and most preferably 0 (zero) mm.

The expression "the location where the clumping portion is located" in this document means the location where the clumping portion 7 of the surface can be visually confirmed in a plan view when looking at the plan view of the surface on the pressure side of the top and rear surfaces of the nonwoven fabric 10 (hereinafter this expression has the same meaning in this document). The expression "a place where the fiber portion is not located" means a place where it is impossible to visually confirm the presence of the fiber portion 7 on the surface in the plan view described above (hereinafter this expression has the same meaning in this document).

[0041]

(Method for measuring thickness of nonwoven fabric under pressure of 7.64 kPa)

A mechanical type thickness gauge with a dial (JIS B7503 (1997) ( JIS - Japanese Industrial Standard ), UPRIGHT DIAL GAUGE made by PEACOCK, pressure of 7.64 kPa, measuring head end: flat type disc with φ5 mm) is used, while measure the thickness T1 of the nonwoven fabric at the location where the bundled portion is located, and measure the thickness T2 of the nonwoven fabric in the location where the bundled portion is not located to determine the difference in thickness given by the equation: T3 = T1 - T2. The measurement is performed at five points or more for each of the T1 and T2 values. Thereafter, the average value for T1 and the average value for T2 are calculated, and their difference is taken as T3. In addition, a load of 7.64 kPa is a measurement condition for detecting the presence of a clumped portion.

[0042]

The texture softness of the nonwoven fabric 10 is expressed as an average coefficient of friction, and a lower value means that the nonwoven fabric 10 has a better texture. As a rule, the value of the average coefficient of friction becomes smaller in the portion in which the fiber portion 7 is not located than in the portion in which the fiber portion 7 is located. However, in the nonwoven fabric 10 of this embodiment, a plurality of fibrous layers are superimposed on each other in the thickness direction and combined into one, thereby reducing the average coefficient of friction at the location where the clumping portion 7 is located. For reasons related to maintaining soft texture, the average coefficient of friction (Q1) of the nonwoven fabric 10 at the location where the bundle portion 7 is located is preferably 2.5 or less, more preferably 2.4 or less, and even more preferably 2 , 3 or less, and in practice 1.6 or more. In particular, the average coefficient of friction (Q1) of the nonwoven fabric 10 at the location where the bundled portion 7 is located is preferably 1.6 or more and 2.5 or less, more preferably 1.6 or more and 2.4 or less, and even more preferably 1.6 or more and 2.3 or less.

For reasons related to the preservation of soft texture, the difference Q3 (= Q1 - Q2) of the average coefficient of friction Q1 of the nonwoven fabric 10 at the location where the fiber portion 7 is located, and the average coefficient of friction Q2 of the nonwoven fabric 10 in the location where there is no the fiber aggregate is located, preferably 0.7 or less, more preferably 0.5 or less, even more preferably 0.32 or less, particularly preferably 0.3 or less, and most preferably 0 (zero).

[0043]

(Method for determining the average coefficient of friction)

A square with a side length of 15 cm is cut from the nonwoven fabric to be measured to determine the MIU (µ) values on the measured surface at the location where the bundled part is located and where the bundled part is not located , under SENS conditions: 2 × 5 and a load of 4.9 kPa using the KES-FB4 Surface Roughness Tester manufactured by Kato Tech Co., Ltd. The measurement is made at five points or more for each of two directions perpendicular to each other (typically for the MD direction and the CD direction), and their average values are taken as MIU (µ) values. The MIU (µ) value is the mean coefficient of friction, and a higher value indicates a rougher surface and a worse feel, and a lower value indicates a smoother surface and a better feel.

[0044]

The aggregate layer 8 mentioned above is preferably the outermost layer of the nonwoven fabric 10. In this case, the aggregate layer 8 may be present in a situation where the aggregate layer 8 is present on only one surface of the top and back surfaces of the nonwoven fabric. 10, or in a situation where the aggregate layer 8 is present on both the top and back surfaces of the nonwoven fabric 10. The aggregate layer 8 is a layer in the outermost layer of the nonwoven fabric 10, thereby maximizing the visual effect.

[0045]

For reasons related to maintaining the soft texture of the nonwoven fabric 10, the number of clumped portions 7 located in the nonwoven fabric 10 is preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less in terms of the average on each zone, which is a square with a side length of 10 cm, in a plan view of the upper and back surfaces of the nonwoven fabric 10 (in a plan view in a state in which the respective fibrous layers are superimposed on each other). On the other hand, for design reasons, the number of clumping portions 7 disposed in the nonwoven fabric 10 is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more in terms of the average on each zone, which is a square with a side length of 10 cm, in a plan view of the upper and back surfaces of the nonwoven fabric 10 (in a plan view in a state in which the respective fibrous layers are superimposed on each other). In particular, the number of fiber-aggregated portions 7 is preferably 5 or more and 50 or less, more preferably 10 or more and 40 or less, and even more preferably 20 or more and 30 or less in terms of the average per zone, which is a square with a side length of 10 cm, in a plan view of the upper and back surfaces of the nonwoven fabric 10 (in a plan view in a state in which the respective fibrous layers are superimposed on each other).

For reasons of reducing the possibility of contact between the skin and the clumping portion 7, the number of the clumping portions 7 in the fibrous layer serving as the skin-facing side of the absorbent article of the fibrous layers superimposed on each other is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less in terms of the average per area, which is a square with a side length of 10 cm, in a plan view of a fibrous layer serving as a surface side facing the skin. The number of the fiber-clumping portions 7 in the fibrous layer serving as the skin-facing surface of the absorbent article is preferably 1 or more. In particular, the number of portions 7 with an accumulation of fibers in the fibrous layer serving as the side of the surface of the absorbent article facing the skin is preferably 1 or more and 30 or less, more preferably 1 or more and 20 or less, and even more preferably 1 or more and 10 or less in terms of the average per zone, which is a square with a side length of 10 cm, in plan view of the fibrous layer serving as the skin-facing side of the surface.

For reasons related to the formation of a pattern on the thickness of the material, the number of portions 7 with accumulation of fibers in the fibrous layer serving as the side of the surface of the absorbent article not facing the skin of two layers superimposed on each other is preferably 3 or more, more preferably 8 or more, and even more preferably 15 or more in terms of the average per zone, which is a square with a side length of 10 cm, in plan view of the fibrous layer serving as the non-skin side of the surface ...

[0046]

For reasons related to maintaining the soft texture of the nonwoven fabric 10, the size (area) of a single clumped portion 7 in a plan view of the nonwoven fabric 10 is preferably 10 mm ² or less, more preferably 8 mm ² or less, and even more preferably 6 mm ² or less. On the other hand, for design reasons, the size of a single clumped portion 7 in a plan view of the nonwoven fabric 10 is preferably 1 mm ² or more, more preferably 2.5 mm ² or more, and even more preferably 4 mm. ² or more. In particular, the size (area) of a single fiber clumped portion 7 in a plan view of the nonwoven fabric 10 is preferably 1 mm ² or more and 10 mm ² or less, more preferably 2.5 mm ² or more and 8 mm ² or less. and even more preferably 4 mm ² or more and 6 mm ² or less.

The size of the clumping portion 7 of the fibrous layer serving as the skin side of the absorbent article in plan view of the nonwoven fabric 10 is preferably 9 mm ² or less, more preferably 7 mm ² or less, and even more preferably 5 mm ² or less.

For reasons related to the patterning of the thickness of the fabric, the size of the clumping portion 7 located in the fibrous layer serving as the non-skin side of the absorbent article of two layers superimposed on each other, in a plan view of a nonwoven material 10 is preferably 2 mm ² or more, more preferably 3 mm ² or more, and even more preferably 5 mm ² or more.

[0047]

For reasons related to maintaining the soft texture of the nonwoven fabric 10, the size (thickness) of a single clumped portion 7 in the thickness direction of the nonwoven fabric 10 is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. on the thickness of the nonwoven fabric 10. On the other hand, for reasons of feeling, the size (thickness) of a single clumped portion 7 in the direction of the thickness of the nonwoven fabric 10 is preferably as small (smaller) as possible in the range of sizes greater than 0% of the thickness of the nonwoven fabric 10. In particular, the size (thickness) of a single clumped portion 7 in the thickness direction of the nonwoven fabric 10 is preferably more than 0% and 50% or less, more preferably more than 0% and 40% or less and even more preferably more than 0% and 30% or less of the thickness of the nonwoven fabric 10.

For reasons related to the weakening of the feeling of hardness when the skin contacts the clumped portion 7 with multiple fibrous layers superimposed on each other and combined in one piece, the size of the clumped portion 7 located in the fibrous layer serves as a surface side of an absorbent article, facing the skin, of two fibrous layers superimposed on each other - in the direction of the thickness of the nonwoven fabric 10 is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less of the thickness of the nonwoven fabric 10 ...

For the same reasons as described above, the size (thickness) of a single clumped portion 7, measured in the thickness direction of the nonwoven fabric 10, is preferably 1 mm or less, more preferably 0.8 mm or less, and even more preferably 0. 5 mm or less, and is preferably as small as possible over a size range of more than 0 mm. In particular, the size (thickness) of a single clumped portion 7, measured in the thickness direction of the nonwoven fabric 10, is preferably greater than 0 mm and 1 mm or less, more preferably greater than 0 mm and 0.8 mm or less, and even more preferably more than 0 mm and 0.5 mm or less.

[0048]

(Method for determining the number of clumped parts, area and thickness)

A square with a side length of 10 cm was cut from the surface of the nonwoven fabric to be examined (for example, from surface 10A in the nonwoven fabric 10), and a photograph was taken using a microscope (VHX-900 manufactured by Keyence Corporation). The data from this photograph (jpeg) is processed through image analysis using image analysis software (NexusNewQube). Binarization is performed to determine the number and area of the clumped portions. In addition, all the clumped portions are cut in the thickness direction using a razor blade, and the sections are examined using the microscope described above to measure the thickness of the nonwoven fabric and the thickness of the clumped portion.

[0049]

The hot air bonded nonwoven fabric for an absorbent article according to the present invention is used as a constituent component of an absorbent article. Examples of an absorbent article include various articles for absorbing and retaining a body fluid, such as diapers, sanitary napkins, urological pads, and panty liners.

The hot air bonded nonwoven fabric for an absorbent article according to the present invention is used as various elements of an absorbent article according to its purpose, and is included in the absorbent article. For example, when the hot air bonded nonwoven is liquid permeable, the hot air bonded nonwoven is included in the absorbent article as a topsheet, and when the hot air bonded nonwoven is water repellent, the hot air bonded nonwoven is included in the absorbent article as a sidewall. sheet. The hot air bonded nonwoven is processed into a thinner and softer material and incorporated into an absorbent article as an outer material to improve texture on the outer side (garment side) of an absorbent article such as diapers.

However, for reasons related to promoting the feel of the nonwoven fabric as having very good bulk and soft texture to the skin and facilitating the visual recognition of the nonwoven fabric pattern, it is preferable that the hot air bonded nonwoven fabric for an absorbent article according to the present invention is placed in the outermost a layer on the skin side of the absorbent article and that the clumping layer 8 is located closer to the skin side of the surface. Examples of this include a topsheet and a sidesheet, and it is particularly preferable that the hot air bonded nonwoven fabric for an absorbent article of the present invention is placed in an absorbent article as a topsheet.

[0050]

Next, a preferred embodiment of a method for manufacturing a hot air bonded nonwoven fabric for an absorbent article according to the present invention will be described. Here, the embodiment has been described as a method for manufacturing the nonwoven fabric 10 according to the embodiment mentioned above. However, the fibrous layers to be stacked are not limited to two layers (fibrous layer 1 and fibrous layer 2), and may be layers formed by overlapping three or more fibrous layers.

[0051]

The manufacturing method of this embodiment includes the following step 501 and step 502.

Step 501: An opening step in which a loosening treatment is applied to thermoplastic fibers a plurality of times to form a web.

Step 502: A step in which a plurality of single-layer webs obtained in the opening step are stacked on top of each other to form a multilayer web, and hot air treatment by passing air is applied to the multi-layer web to obtain an air-bonded nonwoven fabric.

[0052]

In addition, the manufacturing method of this embodiment includes the following step 503.

Step 503: A calendering step in which calendering is applied to one or more of sheets selected from a single web, a multi-layer web, and a hot air bonded nonwoven using a pair of calender rolls.

Step 503 is performed on any one or more of the operations after step 501 and before step 502, during step 502, and after step 502.

[0053]

Fig. 2 shows a manufacturing apparatus 100 preferably used in the method for manufacturing the nonwoven fabric 10 of this embodiment. The production device 100 has - in the direction from the inlet side to the outlet side - devices 101 and 102 for loosening fibrous materials serving as raw materials for nonwoven fabric, cards 103 and 104 for forming fibrous webs, a device 105 for forming a multilayer canvas for for moving the single-layer carded webs and for superimposing the single-layer webs on top of each other; and a web calendering device 106 for performing pressure treatment on the multi-layer web and a heat treatment device 107 (air-through treatment device).

In the manufacturing apparatus 100, the step 501 described above is performed in the loosening devices 101 and 102 and the cards 103 and 104. The step 502 described above is performed in the laminate forming apparatus 105 and the curing apparatus 107.

In the manufacturing apparatus 100, step 503 described above is performed in the canvas calendering apparatus 106. The web calendering apparatus 106 is positioned between the web forming apparatus 105 and the curing apparatus 107, and step 503 described above is performed in the form of web calendering, which is performed on the multilayer web during step 502 described above.

[0054]

Each of the opening devices 101 and 102 has a device for opening the thermoplastic fibers serving as starting materials for the fibrous layers 1 and 2 and for supplying the resulting material to each of the subsequent cards 103 and 104. When using fine fibers and thick fibers, each of which has a certain fiber diameter as indicated above, the opening is preferably carried out separately for thin fibers and thick fibers. FIG. 2 shows that fibers (fine fibers) 71, constituting a starting material, are loaded into a loosening device 101 and loosened (arrow 171), and fibers (thick fibers) 72, constituting a starting material, are loaded into a loosening unit 102 and opened. (arrow 172).

[0055]

As the raw material fibers (fine fibers) 71 and the raw material fibers (thick fibers) 72, various thermoplastic fibers used for the hot air bonded nonwoven fabric can be used. Examples thereof include bicomponent fibers having a core and sheath structure in which the melting point of the polymer component of the sheath is lower than the melting point of the polymer component of the core.

[0056]

The cards 103 and 104 receive (arrows 173 and 174) the fibers opened in each of the openers 101 and 102 to form single-ply webs 81 and 82. In particular, the accumulation of fibers opened in the openers 101 and 102 is carded, and the resulting fibers are further loosened to form a sheet-like web. In the card 103, a single layer web 81 is formed from fibers (fine fibers) 71 constituting a starting material, and in a card 104, a single layer web 82 is formed from fibers (thick fibers) 72 constituting a starting material.

[0057]

Various cards commonly used to make hot air bonded nonwoven fabric can be used in cards 103 and 104 without particular limitation. Examples thereof include a parallel carding card, a semi-random carding card, a random carding card, and a machine in which the cross ply and the stretcher are combined with a carding machine to form a web with parallel arrangement of fibers. In addition, examples of the card include a machine provided with three kinds of rollers, namely a main cylindrical roller covered with a metal sawtooth wire, a work roller and a take-off roller. The accumulation of fibers is carded between the main cylindrical roller and the work roller and the take-off roller, whereby loosening can be performed. A plurality of sets of work rolls and take-off rolls are disposed around the main cylindrical roll, whereby the opening treatment can be performed a plurality of times in each card in the cards 103 and 104.

[0058]

As described above, the opening processing must be performed a plurality of times in both the opening devices 101 and 102 and the cards 103 and 104.

[0059]

In the manufacturing method of this embodiment, an opening step (step 501) is performed in which a loosening treatment is applied to the thermoplastic fibers a plurality of times to form a web in the openers 101 and 102 and the cards 103 and 104.

[0060]

Further, in the apparatus 105 for forming a multi-layer web, a single-layer web 82 formed in a card 104 is applied to a single-layer web 81 formed in a card 103 to form a multi-layer web 90.

In particular, the laminated web 81 is moved from the card 103 along the discharge belt 103A and is placed on the conveyor belt 105A. The conveyor belt 105A moves the single layer web 81 further down the line. The single layer web 82 moves from the card 104 along the discharge belt 104A and is applied to the single layer web 81 during transport. Thus, the formed multi-layer web 90 moves downstream along the conveyor belt 105A. The portions of the multi-layer canvas 90 corresponding to the single-layer canvases 81 and 82 are referred to simply as canvases 81 and 82.

[0061]

In the multilayer canvas 90, canvas 82 is formed from fibers (thick fibers) 72 as a raw material, and a canvas 81 is formed from fibers (thin fibers) 71 as a starting material. Consequently, the average fiber diameter of the web 82 is set to be greater than the average fiber diameter of the web 81. In this configuration, the web 81 is formed as a clumped layer 8 including fine fibers having the specified fiber diameter above, in the finished nonwoven fabric 10. The web 82 can be used as a layer 9 without fiber aggregation, including thick fibers having the specific fiber diameter given above in the finished nonwoven fabric 10. An increase in the basis weight of the layer 9 without fiber aggregation compared to the layer 8 with the accumulation of fibers in the finished nonwoven fabric 10 can be achieved by increasing the mass of fibers supplied from the opener 102 to the card 104 compared to the mass of fibers supplied from the opener 101 to the card 103.

[0062]

Thus, in the manufacturing method of this embodiment, it is preferable to use a plurality of kinds of fibers having different fiber diameters to form a multi-layer web. In particular, it is more preferred that the web 82 and the web 81 have different fiber diameters.

In the case of fibers having different fiber diameters, it is preferable that fine fibers having a fiber diameter of 1 dtex or more and 2.2 dtex or less are used. In addition, it is more preferable that the diameter of the fine fibers falls within the range of fiber diameters indicated above.

[0063]

The web calendering apparatus 106 calenders the web by positioning the movable web 90 between two calendering rolls 106A and 106B to apply pressure to the web 90 (hereinafter referred to simply as "calendering" in some cases). Thus, the surface of the canvas in the portion containing the lint portion 7 can be smoothed to reduce the hardness of the lint portion 7.

[0064]

Specifically, in the manufacturing method of this embodiment, calendering is performed on the laminated web 90 before it is converted into a nonwoven fabric, and therefore, the areas between the fibers are not yet fused and fixed, and the fibers can move to a large extent. That is, in the calendering of this embodiment, there is no risk of peeling, tearing, or the like of the fibers in the fused portion between the fibers, and the fibers accumulated in the clumping portion 7 can be preferentially sampled (the spacing between the fibers increases) when while maintaining good condition of the fibers, and the clumping portion 7 can be flattened appropriately. Thus, the effect of decreasing the hardness of the filament portion 7 is increased. When pressure is applied in the thickness direction by calendering, the fibers bonded to each other in the bundle portion 7 are easily sampled in both webs 81 and 82 superimposed on each other, before converting the webs to nonwoven fabric, and the effect of reducing the hardness of the bundle portion 7 fiber increases in the multi-layer canvas 90 as a whole (hereinafter, the multi-layer canvas, subjected to the calendering of the canvas, in some cases, referred to as the multi-layer canvas 95). In the process flow, the blowing-through treatment mentioned later is performed after the calendering described above is performed, whereby the blowing-through treatment can be used as a nonwoven fabric thickness restoration treatment. That is, in this embodiment, the processing steps performed in this order are essential for restoring the thickness of the laminated web 95 in order to obtain a bulkier and softer texture material and for pattern formation.

[0065]

In the curing apparatus 107, hot air treatment by passing air is applied to the multi-layer web 95, the calendered web.

In particular, the heat treatment device 107 has a casing 107A and a conveyor belt 107B provided with an air-permeable mesh and circulating in the casing 107A. In the casing 107A, hot air is blown from above towards the conveyor belt 107B (arrow F in FIG. 2). The air-permeable mesh described above allows blown hot air to be blown through the conveyor belt 107B. The multi-layer web 95, which has been calendered to the web, is pushed into the calender 107 by rotating the rollers in the web calender 106. In the curing apparatus 107, the laminated web 95 is moved into the casing 107A by means of a conveyor belt 107B. Hot air heated to a predetermined temperature is blown towards the multi-layer web 95 in the casing 107A from above with respect to the multi-layer web 95 (namely, above the web 82) in the thickness direction by a transmission method. That is, the air-passing treatment is applied to the laminated web 95. Thus, in the laminated web 95, the fiber spacing in the clumping portion 7 is increased by the calendering of the web mentioned above, and the intersections of the fibers with each other are fused by blowing hot air while maintaining the fiber state in which the hardness of the fiber clumping portion 7 is reduced. Thus, the hot air-bonded nonwoven fabric 10 for the absorbent article of this embodiment is obtained.

[0066]

As described above, in the manufacturing method of this embodiment, step 502 described above and step 503 described above are performed on the single-layer webs 81 and 82 obtained by the opening operation in step 501 described above by the laminate forming apparatus 105. canvas, device 106 for calendering the canvas and device 107 for heat treatment. Specifically, step 502 is performed by the multi-layer web forming apparatus 105 and the heat-treating apparatus 107, and the calendering step (step 503) is performed by the web calendering apparatus 106 while the web is moving.

By performing these steps 501, 502, and 503, the hot air bonded nonwoven fabric 10 for the absorbent article of this embodiment mentioned above can be produced with a high degree of perfection. That is, even if the hot air bonded nonwoven fabric 10 comprises a fibrous layer 8 containing the fiber clump portion 7, the hot air bonded nonwoven fabric 10 for an absorbent article having a very good bulk and soft texture and having a pattern can be made with high degree of perfection. If necessary, the manufactured hot air bonded nonwoven fabric 10 for an absorbent article is wound onto a roll.

[0067]

In the manufacturing method of this embodiment, the calendering step (step 503) is performed on the multilayer canvas 90 before subjecting the canvas to an air passage treatment. However, the calendering step is not limited to this, and calendering may be performed separately on the single-layer canvas 81 and the single-layer canvas 82 before being superimposed, or calendering may be performed on the hot air bonded nonwoven after the air-through treatment. When calendering is performed on the hot air bonded nonwoven fabric to be processed, the hot air bonded nonwoven fabric to be processed serves as the hot air bonded nonwoven fabric as a starting material before being converted into the hot air bonded nonwoven fabric 10 for the absorbent article of this embodiment ...

[0068]

In the manufacturing method of this embodiment, by performing the calendering step (step 503), the clumped portion 7 is flattened with a calender, and the non-clumped portion 7 is also flattened by calendering to make it smooth. In the nonwoven fabric 10, the surface of which becomes smooth, the thicknesses of the plurality of fibrous layers are retained in the fabric forming one piece, and therefore, the resulting fabric is formed as a product made with such a thickness that the sensation of a foreign object (discomfort) is reduced. when the clumped portion 7 is in contact with the skin and is springable.

In the manufacturing method of this embodiment, the pulp / fiber aggregate may be collapsed / collapsed in the step of making a one-piece nonwoven fabric. Therefore, the need for a fiber accumulation control device used after the production of the nonwoven fabric is eliminated, whereby production costs can be reduced. The need for post-production inspection, subsequent calendering and hot air regeneration treatment is eliminated, and therefore, the efficiency of nonwoven fabrication can be improved.

[0069]

For reasons related to effectively reducing the hardness of the clumped portion 7, the calendering described above is preferably a web calendering performed on one or more sheets selected from a single layer web or a multi-layer web.

[0070]

Calendering is not limited to the case in which calendering is performed in only one step of a single-layer web calendering step, a multi-layer web calendering step and a hot air bonded nonwoven fabric calendering step, and may be performed in two or more of these steps. The calendering is not limited to a case in which the calendering is performed once in each step, and may be performed two or more times. For example, the calendering is not limited to the case in which the calendering on the multi-layer canvas 90 of this embodiment is performed only once, and may be performed two or more times.

[0071]

Linear pressure in the calendering step, namely line pressure applied to the multi-layer web 90, single-layer webs 81 and 82 and the hot air bonded nonwoven fabric (hot air bonded nonwoven fabric constituting the starting material) compressed between the calendering rolls 106A and 106B, preferably is the highest of the line pressures applied to single webs 81 and 82, multi webs 90 and 95, and hot air bonded nonwoven fabric 601 on the side of all shafts / rollers at all stages. The expression "all rolls / rolls" in this document means all rolls / rolls used in all processing operations other than the calender rolls 106A and 106B mentioned above. For example, the term encompasses a nip roll for conveying the nonwoven fabric after heat treatment, a nip roll or nip roll used during winding, a nip roll used during slitting after winding, and the like.

[0072]

In particular, in the calendering step, for reasons related to effectively reducing the hardness of the clumped portion 7 prior to performing thermal fusion, the line pressure (P) applied to the single-layer webs 81 and 82 and the multi-layer web 90 is preferably 20 N / cm or more. more preferably 100 N / cm or more, and even more preferably 180 N / cm or more. In addition, for reasons related to the ability to regain thickness after applying pressure, the line pressure (P) described above is preferably 700 N / cm or less, more preferably 500 N / cm or less, and even more preferably 250 N / cm or less. In particular, the line pressure (P) is preferably 20 N / cm or more and 700 N / cm or less, more preferably 100 N / cm or more and 500 N / cm or less, and even more preferably 180 N / cm or more and 250 N / cm or less.

[0073]

The two calendering rolls 106A and 106B used in the web calendering apparatus 106 are rolls having a smooth peripheral surface. As their material, various materials used for calendering can be used. In addition, the material of the calender roll 106A and the material of the calender roll 106B may be the same or different from each other.

Among other things, for reasons related to further enhancing the effect of reducing the hardness of the fiber bundle portion 7, the calender rolls used for calendering are preferably a combination of a resin roll and a steel roll. When calendering the web of this embodiment, a steel shaft is used as the calender roll 106A, which is a calender roll in contact with the web 82 of the multi-layer web 90 containing thick fibers, and as the calender roll 106B, which is a roll located in A resin roller is used in contact with the web 81 of the laminated web 90 containing fine fibers. However, the arrangement of the resin shaft and the steel shaft is not limited thereto, and an inverse combination may be provided.

[0074]

For reasons related to further enhancing the effect of decreasing the hardness of the fiber clumping portion 7, the hardness of the resin roll described above is preferably 20 units, more preferably 50 units or more, and even more preferably 80 units or more on the Shore D hardness scale. (JIS K 6253-3). For the same reasons as above, the hardness of the polymer roll is preferably 100 units or less, more preferably 95 units or less, and even more preferably 90 units or less on the Shore D hardness scale. (JIS K 6253-3). In particular, the hardness of the resin shaft described above is preferably 20 units or more and 100 units or less, more preferably 50 units or more and 95 units or less, and even more preferably 80 units or more and 90 units or less.

[0075]

The blowing air treatment preferably includes a plurality of blowing air treatments

3 shows an embodiment of a heat treating apparatus (apparatus for passing air treatment) having an apparatus 117 for a first blowing-through treatment and an apparatus 127 for a second treatment by passing air. In this embodiment, the blowing-through treatment is performed twice by the first blowing-through treatment and the second blowing-through treatment. However, the number of times of processing by passing air is not limited to two in FIG. 3, and may be three or more times. When the blowing-through treatment includes three or more blow-by-air treatments, the expression "air blowing treatment at a later stage" with respect to "initial blowing air treatment" means air blowing treatment in blowing air treatment a second time, and after processing by passing air a second time. In the blow-by-air treatment in FIG. 3, performed twice, "initial air-blow-through" means a first blow-through treatment, and "a later-stage blow-through treatment" means a second blow-through treatment. In the step of air passing treatment (air passing treatment performed twice) shown in FIG. 3, hot air is blown into the casing 107C in the first air blowing treatment apparatus 117 (arrow F1), and hot air is blown into the casing 107D into device 127 for the second treatment by passing air (arrow F2). In this case, the multi-layer web 95 subjected to the calendering of the web is continuously conveyed from the first treatment apparatus 117 by passing air into the second treatment apparatus 127 by passing air through the conveyor belt 107B. Thus, the first air passing treatment and the second air passing treatment are continuously applied to the multi-layer web 95.

[0076]

In the blow-by-air processing step described above, it is preferable that the hot air flow rate of the air-blow-through treatment at a later stage is higher than the hot air flow rate of the initial air-blowing treatment, that is, the initial air-blowing treatment is performed at a lower air flow rate. Thus, the decrease in bulk caused by the air pressure in the air-blowing treatment apparatus is suppressed, and the "restorative" effect of the hot air is exerted, resulting in a high bulk of the canvas. In particular, when calendering is performed on the multi-layer web 90 or single-layer webs 81 and 82 before they are converted to a nonwoven fabric as described in this embodiment, the processing described above, which is post-treatment by passing air, is effective.

[0077]

Specifically, the hot air supply speed S1 in the initial air blowing treatment is preferably 0.2 m / s or more, more preferably 0.25 m / s or more, and even more preferably 0.4 m / s or more. The hot air supply speed S1 in the initial air blowing treatment is preferably 1.2 m / s or less, more preferably 0.8 m / s or less, and even more preferably 0.5 m / s or less. In particular, the air supply speed S1 is preferably 0.2 m / s or more and 1.2 m / s or less, more preferably 0.25 m / s or more and 0.8 m / s or less, and even more preferably 0.4 m / s or more and 0.5 m / s or less. Thus, flattening of the canvas is suppressed, and the effect of restoring thickness is exhibited.

[0078]

The hot air supply speed S2 in the air blowing treatment at a later stage is preferably 0.8 m / s or more, more preferably 0.9 m / s or more, and even more preferably 1.2 m / s or less. The hot air blowing speed S2 in the air blowing treatment at a later stage is preferably 1.6 m / s or less, more preferably 1.4 m / s or less, and even more preferably 1.3 m / s or less. In particular, the air supply speed S2 is preferably 0.8 m / s or more and 1.6 m / s or less, more preferably 0.9 m / s or more and 1.4 m / s or less, and even more preferably 1.2 m / s or more and 1.3 m / s or less. Thus, air flows evenly through the web and heat energy is efficiently supplied to the nonwoven fabric structure.

[0079]

The difference S3 (= S2 - S1) of the hot air supply speed S1 in the initial air blowing treatment and the hot air blowing speed S2 in the air blowing treatment at a later stage is preferably greater than 0 m / s, more preferably 0.4 m / s or more, and even more preferably 0.8 m / s or more. The difference S3 (= S2 - S1) of the hot air supply speed S1 in the initial blowing-through treatment and the hot air blowing speed S2 in the air-blowing treatment at a later stage is preferably 1.4 m / s or less, more preferably 1.2 m / s or less, and even more preferably 1 m / s or less. In particular, the difference S3 (= S2 - S1) of the hot air supply speed S1 in the initial blowing-through treatment and the hot air supply speed S2 in the air-blowing treatment at a later stage is preferably more than 0 m / s and 1.4 m / s or less, more preferably 0.4 m / s or more and 1.2 m / s or less, and even more preferably 0.8 m / s or more and 1 m / s or less. Thus, both bulk recovery and nonwoven fabrication can be more effectively achieved.

[0080]

In the air-through-treatment step described above, the temperature of the hot air in the air-through-treatment at a later stage is preferably higher than in the initial air-through treatment. Thus, the fusion of the fibers occurs gradually to efficiently effect the regeneration of the web in the air-through treatment apparatus. In particular, when calendering is performed on the multi-layer web 90 or single-layer webs 81 and 82 before they are converted to a nonwoven fabric as described in this embodiment, the effect described above and provided by the post-processing through air passage is enhanced.

[0081]

In particular, the temperature P1 of the hot air in the initial treatment by passing air is preferably 85 ° C or more, more preferably 90 ° C or more, and even more preferably 100 ° C or more. The temperature P1 of the hot air in the initial air-passing treatment is preferably 134 ° C or less, more preferably 115 ° C or less, and even more preferably 105 ° C or less. In particular, the temperature P1 of the hot air in the initial treatment by passing air is preferably 85 ° C or more and 134 ° C or less, more preferably 90 ° C or more and 115 ° C or less, and even more preferably 100 ° C or more, and 105 ° C or less. Thus, the recovery ability of the canvas in the air-passing treatment apparatus can be effectively manifested.

[0082]

The temperature P2 of the hot air in the treatment by passing air at a later stage is equal to or greater than the melting point of the component on the surface of the fibers to be used (for example, the sheath component in core-sheath bicomponent fibers) and is preferably 145 ° C or less, more preferably 137 ° C or less, and even more preferably 134 ° C. In particular, the temperature P2 of the hot air in the treatment by passing air at a later stage is preferably equal to or greater than the melting point of the component on the surface of the fibers to be used and is 145 ° C. or less, more preferably equal to or greater than the melting point of the component on the surface of the fibers. to be used and is 137 ° C or less, and even more preferably is equal to or more than the melting point of the component on the surface of the fibers to be used and is 134 ° C or less. Thus, the nonwoven fabric having a good-feeling texture can be produced.

[0083]

The difference P3 (= P2 - P1) of the temperature P1 of hot air in the initial processing by passing air and the temperature P2 of hot air in processing by passing air in a later stage is preferably greater than 0 ° C, more preferably 20 ° C or more, and even more preferably 30 ° C or more. The difference P3 (= P2 - P1) of the temperature P1 of hot air in the initial processing by passing air and the temperature P2 of hot air in processing by passing air in a later stage is preferably 60 ° C or less, more preferably 40 ° C or less and more. preferably 35 ° C or less. In particular, the difference P3 (= P2 - P1) of the temperature P1 of hot air in the initial processing by passing air and the temperature P2 of hot air in processing by passing air in a later stage is preferably more than 0 ° C and 60 ° C or less, more preferably 20 ° C or more, 40 ° C or less, and even more preferably 30 ° C or more and 35 ° C or less. Thus, the production of a bulky nonwoven fabric having a good feel can be carried out.

[0084]

As described below, in the method for manufacturing a hot air bonded nonwoven fabric for an absorbent article of this embodiment, it is preferable that unnecessary parts such as scraps / cuttings / pieces generated in processing steps are caught / collected and returned again to the opening step (step 504 ).

At this step 504, the method includes one or both of the step of capturing the cross-end portions of the web in the card used in the opening step described above and the step of partially collecting the hot air bonded nonwoven fabric described above and cutting and loosening portions of the collected hot air bonded nonwoven fabric. The captured / collected web described above and the cut and loosened portion of the hot air bonded nonwoven fabric are fed to the opening step described above. The expression "cut and loosened portion of the hot air bonded nonwoven fabric" means a portion including scraps of cross-end portions, and, without limitation, a product formed during the adjustment of the processing mode or a product that does not meet specifications and formed during the nonwoven fabric manufacturing step.

[0085]

2 shows a specific example of step 504 described above. Suction and trapping of the lateral end (not shown) portions of the single-layer webs 81 and 82 formed in the card of cards 103 and 104 (arrows 181 and 182) is provided. The hot air-bonded nonwoven fabric 10 obtained by performing the air-blowing treatment in the curing apparatus 107 is partially collected (arrow 183). In this case, a portion of the collected hot air bonded nonwoven fabric cannot be used "as is," and therefore, the portion is cut and loosened in the cutting and loosening apparatus 108 to return it to fibrous form.

The collected / trapped web and the cut and loosened portion of the hot air bonded nonwoven fabric are returned to the looser 101 and again loosened and used as a web to form a web (arrow 184). In this case, the material can be returned either to the loosening device 101 or to the loosening device 102, or to both of them. Fig. 2 shows a process in which the material is to be returned to the loosening device 101. When the material is returned to the loosening device 101, it is preferable to properly adjust the amount of new fibers (fine fibers) 71 being loaded, constituting the starting material so that the proportion of fine fibers in the canvas 81 to be formed, it can be kept constant or higher, and so that the content of thick fibers is limited to values of a few percent (for example, remains within 5%). Thus, by forming the clumping portion 7 of the web 81, the nonwoven fabric 10 contains a large amount of fine fibers, and a soft texture on the surface 10A side of the nonwoven fabric 10 can be provided.

The return of material described above is not limited to the embodiment of FIG. 2. For example, the return may take place in an embodiment in which material collected / captured from card 103 is returned to opener 101 and material collected / captured from card 104 is returned to opener 102. It is sometimes preferable to return the cut and open portion the hot-air bonded nonwoven material into the loosening device 102.

[0086]

As described above, according to the manufacturing method of this embodiment, the nonwoven fabric 10 having a very good bulk and soft texture and having a pattern can be preferably produced. In particular, a nonwoven fabric 10 can be advantageously made obtained with physical properties characterized by a thickness T1 and T2 and a difference T3 (= T1 - T2) at a pressure of 7.64 kPa described above and an average friction coefficient Q1 and Q2 and a difference Q3 (= Q1 - Q2). The nonwoven fabric 10 is made with aesthetic characteristics provided by the pattern formed by the fiber portions 7, in particular by the pattern formed by the fiber portion 7 having a reduced thickness.

[0087]

The thus obtained hot air bonded nonwoven fabric for an absorbent article according to the present invention is incorporated as a predetermined component into an absorbent article according to its intended use (inclusion step) in the step of manufacturing the absorbent article. The activation step is preferably a step such as described below. That is, the thus obtained hot-air bonded nonwoven fabric for an absorbent article according to the present invention is cut to a predetermined size or cut to a predetermined shape or the like according to a function for preparing a predetermined material, and the predetermined material is placed in a predetermined position relative to other components. ... In doing so, the resulting material is rotated and folded together with other elements, if necessary, and the resulting material is attached and incorporated into the absorbent article. Thus, the desired absorbent article is manufactured by the step of including the hot air bonded nonwoven fabric for an absorbent article according to the present invention into the absorbent article in the step of making the absorbent article.

Since, inter alia, the hot air bonded nonwoven fabric for an absorbent article of the present invention satisfies both bulk and soft texture requirements and is designed with a pattern that can be visually pleasing to the wearer, it is preferable that the inclusion step described above was the step of incorporating the material into the outermost layer forming member (eg, topsheet or sidesheet) on the skin side of the surface of the absorbent article. In particular, it is preferable that this step is a step of including the nonwoven material in the absorbent article as a topsheet that is in contact with the skin and most attracts the attention of the wearer. It is preferable that the hot air bonded nonwoven fabric for an absorbent article according to the present invention is configured in which a fibrous layer containing a bundle portion is used as the outermost layer of the nonwoven fabric. More preferably, the hot air bonded nonwoven fabric for an absorbent article of the present invention is positioned in the outermost layer on the skin-facing surface of the absorbent article, and that the fibrous layer containing the aggregate portion described above is located closer to the side the surface of the absorbent article facing the skin.

[0088]

In view of the above embodiments, the present invention further discloses hot-air bonded nonwoven fabrics for an absorbent article and methods for manufacturing a hot-air bonded nonwoven fabric for an absorbent article described below.

[0089]

<1> A hot air bonded nonwoven fabric for an absorbent article in which two or more fibrous layers are superimposed on each other, comprising at least one fibrous layer containing thermoplastic fibers and a fiber aggregate portion.

[0090]

<2> The hot air bonded nonwoven fabric for the absorbent article described in the above <1>,

wherein the hot air bonded nonwoven fabric for an absorbent article has fine fibers having a fiber diameter of 1 dtex or more and 2.2 dtex or less, preferably 1 dtex or more, and more preferably 1.2 dtex or more, and preferably 2 dtex or less and more preferably 1.5 dtex or less, and thick fibers having a fiber diameter that is greater than that of the fine fibers, and

wherein the fibrous layer containing the fiber-clumping portion includes fine fibers.

<3> The hot air bonded nonwoven fabric for an absorbent article described in the above <2>, in which the fine fiber content of the fibrous layer containing the aggregate portion is preferably 50 mass%. or more, more preferably 80% of the mass. or more, and even more preferably 100% of the mass.

[0091]

<4> The hot air bonded nonwoven fabric for an absorbent article described in any of the above <1> to <3>, which contains at least one fibrous layer free of a fiber clump portion.

<5> The hot air bonded nonwoven fabric for the absorbent article described in the above <4>,

wherein the hot air bonded nonwoven fabric for an absorbent article has thick fibers having a fiber diameter of more than 2.2 dtex and 7 dtex or less, preferably more than 2.2 dtex and more preferably 4.4 dtex or more and preferably 5.5 dtex or less, and more preferably 5 dtex or less, and fine fibers having a fiber diameter that is less than that of the thick fibers, and

wherein the fibrous layer not containing the fiber-clumping portion includes thick fibers.

<6> The hot air bonded nonwoven fabric for an absorbent article described in the above <5>, in which the thick fiber content of the fibrous layer not containing the aggregate portion is preferably 50 mass%. or more, more preferably 80% of the mass. or more, and even more preferably 100% of the mass.

<7> The hot air bonded nonwoven fabric for an absorbent article described in <5> or <6> above, in which the thick fiber content of the fibrous layer containing the aggregate portion is preferably 50 mass%. or less, more preferably 30% of the mass. or less, and even more preferably 10% of the mass. or less.

<8> The hot air bonded nonwoven fabric for an absorbent article described in any of the above <4> to <7>, in which the average fiber diameter in the fibrous layer not containing the bundled portion is greater than the average fiber diameter in the fibrous layer, containing a portion with an accumulation of fibers.

<9> The hot air bonded nonwoven fabric for an absorbent article described in <8> above, in which the difference between the average fiber diameter of the fibrous layer not containing the aggregate portion and the average fiber diameter of the fibrous layer containing the aggregate portion is greater than 0 dtex and 5.6 dtex or less, preferably 2.2 dtex or more, and more preferably 3 dtex or more, and preferably 4 dtex or less, and more preferably 3.5 dtex or less.

<10> A hot air bonded nonwoven fabric for an absorbent article described in any of the above <4> to <9>, in which the basis weight of the fibrous layer not containing the aggregate portion is greater than the basis weight of the fibrous layer containing the aggregate portion fibers.

<11> The hot air bonded nonwoven fabric for an absorbent article described in <10> above, in which the difference between the basis weight of the fibrous layer not containing the aggregate portion and the basis weight of the fibrous layer containing the aggregate portion is greater than 0 g / m ² and 20 g / m ² or less, preferably 3 g / m ² or more, and more preferably 5 g / m ² or more, and preferably 15 g / m ² or less and more preferably 10 g / m ² or less.

<12> The hot air bonded nonwoven fabric for an absorbent article described in any of <1> to <11> above, wherein the basis weight of the total hot air bonded nonwoven fabric for an absorbent article is 15 g / m ^2, or more and 40 g / m ² or less, preferably 18 g / m ² or more, and more preferably 20 g / m ² or more, and preferably 30 g / m ² or less, and more preferably 25 g / m ² or less.

[0092]

<13> The hot air bonded nonwoven fabric for an absorbent article described in any of the above <1> to <12>, in which, in the case where the thickness of the hot air bonded nonwoven fabric for an absorbent article, measured at a pressure of 7.64 kPa in the location where the fiber portion is located is taken as T1 and the thickness of the hot air bonded nonwoven fabric for the absorbent article measured under the same pressure in the place where the fiber portion is not located is taken as T2, the difference T3 in thickness defined by the equation: T3 = T1 - T2 is 0.4 mm or less, preferably 0.3 mm or less, more preferably 0.2 mm or less, and even more preferably 0 (zero) mm.

<14> The hot air bonded nonwoven for an absorbent article described in any of <1> to <13> above, wherein the average coefficient of friction of the hot air bonded nonwoven for the absorbent article at the location where the portion with fiber accumulation is 1.6 or more and 2.5 or less, preferably 1.6 or more, and preferably 2.4 or less, and more preferably 2.3 or less.

<15> The hot air bonded nonwoven for an absorbent article described in <14> above, wherein the difference in the average coefficient of friction of the hot air bonded nonwoven for the absorbent article at the location where the fiber portion is located and the middle the coefficient of friction of the hot air bonded nonwoven fabric intended for an absorbent article, at a location where the filamentous portion is not located, is 0.7 or less, preferably 0.5 or more, more preferably 0.32 or less, even more preferably 0.3 or more, and particularly preferably 0 (zero).

[0093]

<16> The hot air bonded nonwoven fabric for an absorbent article described in any of the above <1> to <15>, in which the fiber portion is formed with a collapsed shape in which the fibers are collapsed in the direction of the thickness of the nonwoven when viewed from a cross-section of the nonwoven fabric taken in the thickness direction, and the surface of the filamentous portion on the surface side of the nonwoven fabric has a smooth structure.

[0094]

<17> The hot air bonded nonwoven fabric for an absorbent article described in any of the above <1> to <16>, wherein the fibrous layer containing the fiber-aggregated portion is the outermost layer of the hot air bonded nonwoven fabric for an absorbent article ...

<18> An absorbent article comprising a hot air bonded nonwoven fabric for an absorbent article described in any of the above <1> to <17>.

<19> An absorbent article in which the hot air bonded nonwoven fabric for an absorbent article described in <17> above is disposed in the outermost layer on the skin-facing surface of the absorbent article and a fibrous layer containing a fiber-aggregated portion, located closer to the side of the surface facing the skin.

<20> The absorbent article described in the above <18> or <19>, containing a hot-air bonded nonwoven fabric for an absorbent article as a topsheet.

[0095]

<21> A method of making a hot air bonded nonwoven fabric for an absorbent article, comprising:

a loosening step in which a loosening treatment is applied to the thermoplastic fibers a plurality of times to form a web;

a step in which a plurality of single-layer webs obtained in the opening step are stacked on top of each other to form a multi-layer web, and hot air treatment by passing air is applied to the multi-layer webs to obtain an air-bonded nonwoven fabric; and

a calendering step in which calendering is applied to one or more of sheets selected from a single-layer web, a multi-layer web, and a hot air bonded nonwoven fabric using a pair of calender rolls.

<22> The method of making a hot air bonded nonwoven fabric for an absorbent article as described in <21> above, wherein the line pressure in the calendering step is the highest of the line pressures applied to the single layer web, the laminated web, and the hot air bonded nonwoven fabric in all the steps of a method for making a hot air bonded nonwoven fabric for an absorbent article.

<23> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in <21> or <22> above, wherein the calendering step is a web calendering performed on one or more sheets selected from a single-layer web and a multi-layer web ...

<24> The method for manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in <23> above, wherein in the step of calendering the canvas, the line pressure applied to the single-ply web or multi-layer web is 20 N / cm or more and 700 N / cm or less, preferably 100 N / cm or more, and more preferably 180 N / cm or more, and preferably 500 N / cm or less, and more preferably 250 N / cm or less.

<25> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article described in any of the above <21> to <24>, wherein the pair of calender rolls used for the calendering step is a combination of a resin roll and a steel roll.

<26> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in <25> above, wherein the hardness of the resin roll is 20 units or more and 100 units or less, preferably 50 units or more, and more preferably 80 units or more and preferably 95 Shore D or less, and more preferably 90 Shore D or less.

[0096]

<27> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article described in any of the above <21> to <26>,

in which the treatment by passing air includes a plurality of treatments by passing air, and

and the rate of supply of hot air in the processing by passing air at a later stage is greater than the rate of supply of hot air during the initial processing by passing air.

<28> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in <27> above, wherein the hot air flow rate in the initial air blowing treatment is 0.2 m / s or more and 1.2 m / s or less, preferably 0.25 m / s or more, and more preferably 0.4 m / s or more, and preferably 0.8 m / s or less, and more preferably 0.5 m / s or less.

<29> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in <27> or <28> above, wherein the hot air flow rate in the air blowing treatment at a later stage is 0.8 m / s or more and 1.6 m / s or less, preferably 0.9 m / s or more, and more preferably 1.2 m / s or more, and preferably 1.4 m / s or less, and more preferably 1.3 m / s or less.

<30> The method for manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in any of the above <27> to <29>, wherein the difference in the flow rate of the hot air in the initial blowing-through treatment and the flow rate of the hot air in the blow-by treatment air at a later stage is more than 0 m / s and 1.4 m / s or less, preferably 0.4 m / s or more and more preferably 0.8 m / s or more, and preferably 1.2 m / s or less, and more preferably 1 m / s or less.

<31> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article described in any of the above <21> to <30>,

in which the treatment by passing air includes a plurality of treatments by passing air, and

and the temperature of the hot air in the air-blowing treatment at a later stage is higher than the temperature of the hot air in the initial air-blowing treatment.

<32> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in <31> above, wherein the temperature of the hot air in the initial treatment by passing air is 85 ° C or more and 134 ° C or less, preferably 90 ° C or more and more preferably 100 ° C or more, and preferably 115 ° C or less, and more preferably 105 ° C or less.

<33> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in <31> or <32> above, in which the temperature of the hot air in the air passing treatment at a later stage is equal to or greater than the melting point of the component on the surface of the fibers, to be used and is 145 ° C or less, preferably equal to or greater than the melting point of the component on the surface of the fibers to be used, and is preferably 137 ° C or less, and more preferably 134 ° C or less.

<34> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article described in any of the above <31> to <33>, wherein the difference in temperature of the hot air during initial processing by passing air and the temperature of hot air during processing by passing air to the later stage is more than 0 ° C and 60 ° C or less, preferably 20 ° C or more, and more preferably 30 ° C or more, and preferably 40 ° C or less, and more preferably 35 ° C or less.

[0097]

<35> A method of manufacturing a hot air bonded nonwoven fabric for an absorbent article described in any of the above <21> to <34>, comprising one or both of:

a step of capturing the cross-end portions of the web in the card used in the opening step, and

a step in which the hot air bonded nonwoven fabric is partially collected and a portion of the collected hot air bonded nonwoven fabric is cut and opened,

the collected web and the cut and loosened portion of the hot air-bonded nonwoven are fed to the opening step.

[0098]

<36> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article described in any of the above <21> to <35>, wherein the multilayer web contains a plurality of fibers having different fiber diameters.

<37> The method of manufacturing a hot air bonded nonwoven fabric for an absorbent article as described in any of the above <21> to <36>, wherein the multilayer web comprises fine fibers having a fiber diameter of 1 dtex or more and 2.2 dtex or less , preferably 1 dtex or more, and more preferably 1.2 dtex or more, and preferably 2 dtex or less, and more preferably 1.5 dtex or less.

[0099]

<38> A method of manufacturing an absorbent article, comprising the step of including a hot air bonded nonwoven fabric for an absorbent article made by the manufacturing method described in any of the above <21> to <37> into an absorbent article.

<39> The method of manufacturing an absorbent article as described in the above <38>, comprising the step of including a hot air bonded nonwoven fabric for an absorbent article in an absorbent article as a topsheet.

EXAMPLES

[0100]

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. An arrow pointing to the left ʺ ← ячейки means that the contents of the table cell are the same as those shown in the left column pointed to by the arrow.

[0101]

(Example 1)

A nonwoven sample of Example 1 was produced using the manufacturing apparatus shown in FIG. 2 as shown below at a processing speed of 10 m / min.

First of all, core-sheathed thermoplastic fibers (core: polyethylene terephthalate, sheath: polyethylene) having a fiber diameter of 1.4 dtex were used as fibers (fine fibers) 71 constituting the starting material for forming the fibrous layer 1. Fibers 71 were used as a starting material, and the opening treatment was applied thereto a plurality of times in the opener 101 and card 103 to obtain a single layer web 81 having a basis weight of 10 g / m ² .

In addition, core-sheathed thermoplastic fibers (core: polyethylene terephthalate, sheath: polyethylene) having a fiber diameter of 4.4 dtex were used as the fibers (thick fibers) 72 constituting the starting material for forming the fibrous layer 2. Were used fibers 72 as a starting material, and the opening treatment was applied to them many times in the opener 102 and the card 104 to obtain a single layer canvas 82 having a basis weight of 15 g / m ² .

Next, in the web calendering apparatus 105, a single layer web 82 was applied to a single web 81 to form a web 90. In a web calendering apparatus 106, web calendering was applied to a web 90. The web calendering apparatus 106 used a steel calender roll 106A from the side the upper layer and polymer roll 106B (90 Shore D) on the lower layer side, and the line pressure was adjusted to 200 N / cm.

In the heat-treating apparatus 107, an air-passing treatment in which the air-blowing treatment operation shown in FIG. 3 is performed twice was applied to the calendered laminated web 95. The air flow rate and temperature in the first air passing treatment and the second air passing treatment were adjusted to the values shown in Table 1. Thus, a nonwoven fabric sample was prepared in Example 1.

In addition, in the manufacturing method described above, the operation of collecting / capturing the laterally end portions of the forming web and the nonwoven fabric portion to return the collected materials to the opening step was not performed. Therefore, as a result, the average fiber diameter of the fibrous layer 1 determined by the diameter of the fibers (fine fibers) 71 constituting the starting material was obtained, and the average fiber diameter of the fibrous layer 2 determined by the diameter of the fibers (thick fibers) 72 constituting the starting material was obtained.

[0102]

(Examples 2-7)

Samples of nonwoven fabrics in Examples 2-7 were prepared in the same way as in Example 1, except that the temperature and air flow rate in the first treatment by passing air were adjusted to the values shown in Table 1.

[0103]

(Example 8)

The nonwoven sample in Example 8 was prepared in the same manner as in Example 1, except that no web calendering was performed, and the nonwoven fabric calendering shown in Table 1 was performed on the nonwoven fabric after being blown through.

[0104]

(Example 9)

A nonwoven sample in Example 9 was prepared in the same manner as in Example 1, except that the diameter of the fibers (fine fibers) constituting the starting material for forming fibrous layer 1 was adjusted to 2.0 dtex, and the temperature and the air flow rate in the first air-blowing treatment was adjusted to the values shown in Table 1.

[0105]

(Example 10)

The nonwoven sample in Example 10 was prepared in the same manner as in Example 9, except that the diameter of the fibers 72, which is the starting material for forming the fibrous layer 2, was adjusted to 2.0 dtex.

[0106]

(Example 11)

A sample of nonwoven fabric in Example 11 was prepared in the same manner as in Example 10, except that the diameter of the fibers (fine fibers) constituting the starting material for forming the fibrous layer 1 and the diameter of the fibers 71 constituting the starting material for the formation of the fibrous layer 2 (bottom layer) were brought to a value of 1.4 dtex.

[0107]

(Example 12)

The nonwoven fabric sample in Example 12 was prepared in the same way as in Example 11, except that the temperature and air flow rate in the first air-through treatment were adjusted to the values shown in Table 2.

[0108]

(Example 13)

The nonwoven sample in Example 13 was prepared in the same manner as in Example 12, except that no web calendering was performed, and the nonwoven fabric calendering shown in Table 2 was performed on the nonwoven fabric after being blown through.

[0109]

(Comparative example 1)

The nonwoven fabric sample in Comparative Example 1 was prepared in the same manner as in Example 1, except that no web calendering was performed.

[0110]

(Comparative example 2)

The nonwoven fabric sample in Comparative Example 2 was prepared in the same manner as in Comparative Example 1, except that the diameter of the fibers 71 constituting the starting material for forming the fibrous layer 2 (bottom layer) was adjusted to 1.4 dtex.

[0111]

(Trials)

[1] Volume

(1) Thickness of a nonwoven fabric sample under a load of 0.05 kPa

The measurement was performed using a laser sensor (model number: ZS – LD80) and a controller (model number: ZS – LDC11) manufactured by OMRON Corporation as a laser thickness gauge.

In measuring the thickness, a weight (applying a pressure of 0.05 kPa) was placed between the end of the laser sensor and the nonwoven sample to be measured, and the thickness was measured in that state with the applied pressure. The measurement was respectively carried out at 5 or more points, and the average value was taken as the thickness. In addition, 0.05 kPa is the load assumed for the apparent thickness of the nonwoven fabric to avoid reducing the thickness of the nonwoven fabric as much as possible.

(2) Thickness of 7.64 kPa nonwoven fabric sample

The thickness (T1) of each nonwoven fabric sample at the location where the bundled portion was located and the thickness (T2) where the bundled portion was not located, respectively, were measured based on the method described in (Thickness Measurement Method non-woven fabric at 7.64 kPa) above. The difference in thickness was calculated (T3 = T1 - T2).

[2] Friction

The MIU (µ) (Q1) value for each nonwoven sample at the location where the bundled portion was located and the MIU (µ) (Q2) value in the location where the bundled portion was not located were respectively determined based on the method described in (Method for determining the average coefficient of friction) above. The difference between Q3 values MIU (µ) (= Q1 - Q2) was calculated.

[3] Figure

The presence or absence of the clumped portion was visually confirmed for each nonwoven sample.

[0112]

[Table 1]

Table 1

Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex.6 Ex. 7 Ex. 8 Technical characteristics of nonwoven fabric Fiber composition Fibrous layer 1 PET / PE
1.35 dtex
100% ← ← ← ← ← ← ← Fibrous layer 2 PET / PE
4.4 dtex
100% ← ← ← ← ← ← ← Surface density
(Fiber layer 1 / Fiber layer 2 g / m ² 10/15 10/15 10/15 10/15 10/15 10/15 10/15 10/15 Processing conditions Canvas calendering
Upper: Steel shaft
Bottom: Polymer shaft D-hardness: 90 N / cm 200 200 200 200 200 200 200 0 Temperature during first treatment by passing air ° C 136 136 115 105 105 105 85 136 Air flow rate for first treatment by passing air m / s 1,2 0,4 0,4 1,2 0.8 0,4 0,4 1,2 Temperature in the second treatment by passing air ° C 136 136 136 136 136 136 136 136 Air flow rate for second treatment by passing air m / s 1,2 1,2 1,2 1,2 1,2 1,2 1,2 1,2 Calendering nonwoven fabric
Upper: Steel shaft
Bottom: Polymer shaft, D-hardness: 90 N / cm 0 0 0 0 0 0 0 200 Fiber opening treatment has been done multiple times * 1 YES YES YES YES YES YES YES YES Processing speed m / min ten ten ten ten ten ten ten ten

Notes: “Ex.” Means Example according to the present invention.

Note * 1: "YES" means that the fiber opening treatment has been performed multiple times.

Table 1 (continued - 1)

Ex. 9 Ex. 10 Comp. Ex. 1 Technical characteristics of nonwoven fabric Fiber composition Fibrous layer 1 PET / PE
2.0 dtex
100% PET / PE
2.0 dtex
100% PET / PE
1.35 dtex
100% Fibrous layer 2 PET / PE
4.4 dtex
100% PET / PE
2.0 dtex
100% PET / PE
4.4 dtex
100% Surface density
(Fiber layer 1 / Fiber layer 2 g / m ² 10/15 10/15 10/15 Processing conditions Canvas calendering
Upper: Steel shaft
Bottom: Polymer shaft, D-hardness: 90 N / cm 200 200 0 Temperature during first treatment by passing air ° C 105 105 136 Air flow rate for first treatment by passing air m / s 0,4 0,4 1,2 Temperature in the second treatment by passing air ° C 136 136 136 Air flow rate for second treatment by passing air m / s 1,2 1,2 1,2 Calendering nonwoven fabric
Upper: Steel shaft
Bottom: Polymer shaft, D-hardness: 90 N / cm 0 0 0 Fiber opening treatment has been done multiple times * 1 YES YES YES Processing speed m / min ten ten ten

Notes: “App.” Means Example according to the present invention, and “Cf. pr. means Comparative example.

Note * 1: "YES" means that the fiber opening treatment has been performed multiple times.

Table 1 (continued - 2)

Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex.6 Ex. 7 Ex. 8 Volume Non-woven fabric thickness
(0.05 kPa) mm 1.80 2.03 2.08 1.74 2.19 2.18 2.16 1.23 Thickness (T2) of the nonwoven fabric where the bundled portion was not located (7.64 kPa) mm 0.13 0.17 0.17 0.17 0.16 0.15 0.15 0.13 Thickness (T1) of the nonwoven fabric where the clumping portion was located (7.64 kPa) mm 0.33 0.39 0.37 0.35 0.35 0.39 0.39 0.33 T3 = T1 - T2 mm 0.20 0.22 0.20 0.18 0.19 0.24 0.24 0.20 Sensation Average coefficient of friction (Q2) of the nonwoven fabric in the place where the fiber bundle was not located MIU
(µ) 2.00 2.10 2.03 2.10 2.13 2.11 2.06 2.03 Average coefficient of friction (Q1) of the nonwoven fabric at the location where the bundled portion was located MIU
(µ) 2.31 2.30 2.26 2.30 2.34 2.31 2.30 2.30 Q3 = Q1 - Q2 MIU
(µ) 0.31 0.20 0.23 0.20 0.21 0.20 0.24 0.27 Drawing The presence or absence of a part with an accumulation of fibers There is There is There is There is There is There is There is There is The place where there was a part with an accumulation of fibers Fiber layer 1 Fiber layer 1 Fiber layer 1 Fiber layer 1 Fiber layer 1 Fiber layer 1 Fiber layer 1 Fiber layer 1

Notes: “Ex.” Means Example according to the present invention.

Table 1 (continued - 3)

Ex. 9 Ex. 10 Wed Ex. 1 Volume Non-woven fabric thickness
(0.05 kPa) mm 2.12 1.29 2.92 Thickness (T2) of the nonwoven fabric where the bundled portion was not located (7.64 kPa) mm 0.17 0.14 0.16 Thickness (T1) of the nonwoven fabric where the clumping portion was located (7.64 kPa) mm 0.32 0.32 0.57 T3 = T1 - T2 mm 0.15 0.18 0.41 Sensation Average coefficient of friction (Q2) of the nonwoven fabric in the place where the fiber bundle was not located MIU
(µ) 2.05 1.98 2.22 Average coefficient of friction (Q1) of the nonwoven fabric at the location where the bundled portion was located MIU
(µ) 2.16 2.16 3.05 Q3 = Q1 - Q2 MIU
(µ) 0.11 0.18 0.83 Drawing The presence or absence of a part with an accumulation of fibers There is There is There is The place where there was a part with an accumulation of fibers Fibrous layer 1 Fibrous layer 1 Fibrous layer 1

Notes: “App.” Means Example according to the present invention, and “Cf. pr. means Comparative example.

[0113]

[Table 2]

table 2

Ex 11 Ex 12 Ex.13 Wed Ex. 2 Specifications of nonwoven fabric Fiber composition Fibrous layer 1 PET / PE
1.35 dtex
100% ← ← PET / PE
1.35 dtex
100% Fibrous layer 2 PET / PE
1.35 dtex
100% ← ← PET / PE
1.35 dtex
100% Surface density
(Fiber layer 1 / Fiber layer 2 g / m ² 10/15 10/15 10/15 10/15 Processing conditions Canvas calendering
Upper: Steel shaft
Bottom: Polymer shaft, D-hardness: 90 N / cm 200 200 0 0 Temperature during first treatment by passing air ° C 105 136 136 136 Air flow rate for first treatment by passing air m / s 0,4 1,2 1,2 1,2 Temperature in the second treatment by passing air ° C 136 136 136 136 Air flow rate for second treatment by passing air m / s 1,2 1,2 1,2 1,2 Calendering nonwoven fabric
Upper: Steel shaft
Bottom: Polymer shaft, D-hardness: 90 N / cm 0 0 200 0 Fiber opening treatment has been done multiple times * 1 YES YES YES YES Processing speed m / min ten ten ten ten

Notes: “App.” Means Example according to the present invention, and “Cf. pr. means Comparative example.

Note * 1: "YES" means that the fiber opening treatment has been performed multiple times.

Table 2 (continued - 1)

Ex 11 Ex 12 Ex.13 Wed Ex. 2 Volume Non-woven fabric thickness
(0.05 kPa) mm 1.15 0.97 0.80 2.57 Thickness (T2) of the nonwoven fabric where the bundled portion was not located (7.64 kPa) mm 0.17 0.14 0.12 0.15 Thickness (T1) of the nonwoven fabric where the clumping portion was located (7.64 kPa) mm 0.36 0.35 0.34 0.58 T3 = T1 - T2 mm 0.19 0.21 0.22 0.43 Sensation Average coefficient of friction (Q2) of the nonwoven fabric in the place where the fiber bundle was not located MIU
(µ) 1.83 1.69 1.94 2.26 Average coefficient of friction (Q1) of the nonwoven fabric at the location where the bundled portion was located MIU
(µ) 2.28 2.30 2.30 3.02 Q3 = Q1 - Q2 MIU
(µ) 0.45 0.61 0.36 0.76 Drawing The presence or absence of a part with an accumulation of fibers There is There is There is There is The place where there was a part with an accumulation of fibers Fiber layers 1 and 2 Fiber layers 1 and 2 Fiber layers 1 and 2 Fiber layers 1 and 2

Notes: “App.” Means Example according to the present invention, and “Cf. pr. means Comparative example.

[0114]

As shown in Tables 1 and 2, in Examples 1-13, the difference T3 between the thickness T1 at the location where the clumped portion was located and the thickness T2 where the clumped portion was not located under a pressure of 7.64 kPa was less, and the bulk of the nonwoven overall was better than Comparative Examples 1 and 2. Specifically, in Examples, the heat-treated nonwoven after web calendering was obtained as a nonwoven that was thicker and gave a better feel. in the fiber clumping portion than the material calendered after the nonwoven was formed.

In Examples 1 to 3, when confirming the presence of a pattern formed by the portions with an accumulation of fibers, all indicators representing the average coefficient of friction Q1 in the place where the portion with the accumulated fibers was located, the average coefficient of friction Q2 in the place where the portion was not located with accumulation of fibers, and the difference Q3 of both coefficients of friction were smaller and a softer texture of the nonwoven fabric as a whole was provided compared to Comparative Examples 1 and 2.

As described above, in Examples 1-13, the nonwovens were formed with very good bulk and soft texture, and were also made with the aesthetic characteristics provided by the pattern.

[0115]

The invention has been described in connection with these embodiments, aspects and Examples, and it is intended that the invention should not be limited by any of the details in the description unless otherwise stated, but rather should be construed broadly within its spirit and scope as given. in the accompanying claims.

DESCRIPTION OF REFERENCE POSITIONS

[0116]

1 Fibrous layer

2 Fibrous layer

3 Part with clumped fibers

8 Clumping layer (fibrous layer containing the clumped portion)

9 Non-agglomerated layer (fibrous layer not containing the aggregate portion)

10 Hot air bonded nonwoven fabric for absorbent article

100 Device for making hot air bonded nonwoven fabric for absorbent article

101, 102 Loosening device

103, 104 Card

105 Device for forming a multilayer canvas

106 Canvas calendering device

106A, 106B Calender roll

107 Heat treatment device (air treatment device)

117 Device for first treatment by passing air

127 Device for the second treatment by passing air

108 Cutting and loosening device

71, 72 Raw material fibers

81, 82 Single layer canvas (or canvas)

90 Layered Canvas

95 Multi-layer canvas, calendered canvas

Claims (31)

1. A hot air bonded nonwoven fabric for an absorbent article, in which two or more fibrous layers are superimposed on each other, comprising at least one fibrous layer containing thermoplastic fibers and a fibrous portion formed by thermoplastic fibers. 2. The hot air bonded nonwoven fabric for an absorbent article according to claim 1, wherein the fiber-clumping portion is heat-fused. 3. A hot air bonded nonwoven fabric for an absorbent article, in which two or more fibrous layers are superimposed on each other, comprising at least one fibrous layer containing thermoplastic fibers and a fiber aggregate portion, while, in the case where the thickness of the hot-air bonded nonwoven fabric for an absorbent article measured at a pressure of 7.64 kPa at the location where the fiber portion is located is T1, and the thickness of the hot-air bonded nonwoven fabric for an absorbent article measured at under the same pressure in a place where the part with an accumulation of fibers is not located is taken as T2, the difference T3 of the thicknesses, determined by the equation: T3 = T1 - T2, is 0.3 mm or less. 4. A hot air bonded nonwoven fabric for an absorbent article in which two or more fibrous layers are superimposed on each other, comprising at least one fibrous layer containing thermoplastic fibers and a fiber aggregate portion, wherein the fibrous layer containing the aggregate portion is the outermost layer of the hot air bonded nonwoven for an absorbent article, and the hot air bonded nonwoven for an absorbent article is disposed in the outermost layer on the skin-facing side of the surface of the absorbent article. 5. Bonded by hot air nonwoven fabric for an absorbent article according to any one of claims. 1-4, which contains at least one fibrous layer that does not contain a portion with an accumulation of fibers, wherein the areal density of the fibrous layer not containing the aggregate portion is greater than the areal density of the fibrous layer containing the aggregate portion, and the difference between the areal density of the fibrous layer not containing the aggregate portion and the areal density of the fibrous layer containing the aggregate portion is more than 0 g / m ² and 20 g / m ² or less. 6. Bonded by hot air non-woven material for an absorbent article according to any one of paragraphs. 1-5, in which the average coefficient of friction at the location where the bundled portion is located is 1.6 or more and 2.5 or less. 7. The hot air bonded nonwoven fabric for an absorbent article according to claim 6, wherein the difference between the average coefficient of friction at the location where the fiber portion is located and the average coefficient of friction where the fiber portion is not located is 0 , 7 or less. 8. Bonded by hot air non-woven material for an absorbent article according to any one of claims. 1-7, wherein the hot air bonded nonwoven fabric for an absorbent article has fine fibers having a fiber diameter of 1 dtex or more and 2.2 dtex or less, and thick fibers having a fiber diameter that is larger than that of the fine fibers, and wherein the fibrous layer containing the aggregate portion contains fine fibers, and the content of fine fibers in the fibrous layer containing the clumped portion is preferably 50 wt%. or more. 9. Absorbent product containing a hot air bonded nonwoven material for an absorbent product according to any one of claims. 1-8. 10. A method of making a hot air bonded nonwoven fabric for an absorbent article, comprising: a loosening step in which a loosening treatment is applied to the thermoplastic fibers a plurality of times to form a web; a step in which a plurality of single-layer webs obtained in the opening step are stacked on top of each other to form a multi-layer web, and hot air treatment by passing air is applied to the multi-layer web to obtain a hot-air bonded nonwoven fabric; and a canvas calendering step in which the canvas is calendered on one or more sheets selected from the single-layer canvas and the multi-layer canvas. 11. A method of making a hot air bonded nonwoven fabric for an absorbent article, comprising: a loosening step in which a loosening treatment is applied to the thermoplastic fibers a plurality of times to form a web; a step in which a plurality of single-layer webs obtained in the opening step are stacked on top of each other to form a multi-layer web, and hot air treatment by passing air is applied to the multi-layer web to obtain a hot-air bonded nonwoven fabric; and a calendering step in which calendering is applied to one or more of sheets selected from a single-layer web, a multi-layer web and a nonwoven fabric bonded with hot air using a pair of calender rolls, wherein the air-through treatment includes a plurality of air-through treatments. 12. A method of manufacturing a hot air bonded nonwoven fabric for an absorbent article according to claim 10 or 11, in which the treatment by passing air includes a plurality of treatments by passing air, and and the rate of supply of hot air in the processing by passing air at a later stage is greater than the rate of supply of hot air during the initial processing by passing air. 13. A method of manufacturing a hot air bonded nonwoven fabric for an absorbent article according to any one of claims. 10-12, in which the treatment by passing air includes a plurality of treatments by passing air, and and the temperature of the hot air in the air-blowing treatment at a later stage is higher than the temperature of the hot air in the initial air-blowing treatment.

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