JP6667047B1 - Air-through nonwoven fabric for absorbent articles - Google Patents

Abstract

An air-through nonwoven fabric (10) in which two or more fiber layers (1, 2) are laminated, and has at least one fiber layer (8) containing thermoplastic fibers and having a fiber lump portion (7). An air-through nonwoven fabric for absorbent articles (10).

Description

  The present invention relates to an air-through nonwoven fabric for absorbent articles.

The air-through nonwoven fabric is formed by blowing hot air by an air-through method to thermally fuse the intersections of the fibers, so that the air-through nonwoven fabric can be relatively thick and feel good. Therefore, it is often used as a constituent member of an absorbent article. Various proposals have been made on this air-through nonwoven fabric for absorbent articles.
For example, in Patent Literature 1, from the viewpoint of imparting aesthetics by a pattern without impairing the feel, the difference between the thickness of a portion with a small fiber mass and the thickness of a portion without a small fiber mass under a pressure of 7.64 kPa is set to 1 mm or less. An air-through nonwoven is described. As a method for producing this air-through nonwoven fabric, it is described that calendering is performed on a preliminary nonwoven fabric obtained by hot-air blowing. Patent Document 2 discloses an absorbent article provided with a nonwoven fabric having thermoplastic synthetic fibers and organic cotton fibers. In the nonwoven fabric, organic cotton fibers are arranged in a plurality of fiber masses. The organic cotton fibers are not heat-sealed, but are retained in the nonwoven fabric by the entanglement of the fibers.
Patent Literature 3 describes that a completed nonwoven fabric is subjected to pressure treatment between a pair of rolls at a specific linear pressure and temperature from the viewpoint of improving the texture of the nonwoven fabric.
Patent Literature 4 describes a processing method in which a fiber sheet wound in a roll shape is fed, hot air is blown by an air-through method, and calendering is performed at a specific linear pressure.

JP 2013-151774 A JP 2017-202265 A JP-A-60-126365 JP 2006-299480 A

  The present invention provides an air-through nonwoven fabric for an absorbent article, which is an air-through nonwoven fabric in which two or more fiber layers are laminated, and includes at least one fiber layer containing thermoplastic fibers and having a fiber lump. .

  The present invention also provides a fiber-spreading step of performing a fiber-spreading process on thermoplastic fibers a plurality of times to form a web, and laminating a plurality of single-layer webs obtained in the fiber-spreading step to form a laminated web. Subjecting the laminated web to air-through processing with hot air to obtain an air-through nonwoven fabric, and calendering the one or more selected from the single-layer web, the laminated web and the air-through nonwoven fabric using a pair of calender rolls. And a method for producing an air-through nonwoven fabric for an absorbent article.

  The above and other features and advantages of the present invention will become more apparent from the following description, appropriately referring to the accompanying drawings.

It is sectional drawing which shows typically one preferable embodiment of the air-through nonwoven fabric for absorbent articles of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows one preferable embodiment of the manufacturing method and manufacturing apparatus of the nonwoven fabric of this invention. It is a schematic structure figure showing another preferred embodiment of a heat treatment part which performs an air through process in this embodiment.

Detailed description of the invention

  The present invention relates to the provision of a patterned air-through nonwoven fabric for an absorbent article which is excellent in bulkiness and soft touch.

In the manufacturing process of the air-through nonwoven fabric, when the fibers are spread and formed into a web, the fibers may be entangled with each other to form a fiber mass partially. In particular, the smaller the fiber diameter, the more easily the fiber mass is generated. When the fiber mass is subjected to an air-through processing step using hot air as it is, the fiber mass is cured by heat fusion between the fibers.
On the other hand, conventionally, as described in Patent Documents 1, 3, and 4, calendering is performed on the completed nonwoven fabric to reduce the hardness. However, calendering is a process in which the air-through nonwoven fabric is pressed between a pair of rolls, and the air-through nonwoven fabric after the pressurization becomes thinner, so that there is room for improvement in bulkiness. Even if non-woven fabrics described in Patent Documents 1, 3 and 4 are subjected to hot air treatment after calendering, there is a limit to the recovery of the thickness of the non-woven fabric once collapsed, and there is room for further improvement. was there. In this respect, there is no suggestion in Patent Document 3 regarding the restoration of bulkiness.
In air-through nonwoven fabrics for absorbent articles, it is strongly desired that both the bulkiness and the soft touch be further improved, from the viewpoints of the absorbency and cushioning properties of the absorbent articles.

  On the other hand, the air-through nonwoven fabric for absorbent articles of the present invention is excellent in bulkiness and soft touch, and has a pattern. Further, according to the production method of the present invention, the air-through nonwoven fabric for absorbent articles can be produced with high accuracy.

Hereinafter, the air-through nonwoven fabric for absorbent articles of the present invention will be described with reference to the drawings.
The air-through nonwoven fabric for an absorbent article of the present invention can be applied to various absorbent articles that are attached to a body and absorb body fluid, and can be applied to various constituent members such as a surface sheet in the absorbent article.

In the present invention, unless otherwise specified, the side in contact with the human body is referred to as the skin side or the skin contact side or the front side, and the opposite side is referred to as the non-skin side or the non-skin contact side or the back side. .
In the present invention, the “air-through nonwoven fabric” is one in which heat-fusible fibers are heat-sealed at intersections and integrated. The air-through method is used for manufacturing this nonwoven fabric. The air-through method refers to a method in which hot air is blown onto a fibrous web containing heat-fusible fibers in a penetrating manner to fuse intersections of the webs to form a nonwoven fabric.

  The air-through nonwoven fabric for absorbent articles of the present invention is an air-through nonwoven fabric in which two or more fiber layers are laminated. The number of the fiber layers to be laminated may be two or three or more. Since the air-through nonwoven fabric for an absorbent article of the present invention has two or more layers, it becomes possible to obtain a bulky nonwoven fabric that exceeds manufacturing restrictions as compared with a case where a nonwoven fabric is formed with one layer.

  FIG. 1 shows an air-through nonwoven fabric 10 for an absorbent article (hereinafter simply referred to as a nonwoven fabric 10) in which two fiber layers (fiber layers 1 and 2) are laminated as a preferred embodiment of the air-through nonwoven fabric for an absorbent article of the present invention. ). The fiber layer 1 and the fiber layer 2 contain heat-fusible fibers, and the contact surfaces of both layers are joined over the entire area by fusion of the heat-fusible fibers. Therefore, the nonwoven fabric 10 does not have a region where the fiber layer 1 and the fiber layer 2 are separated from each other. That is, the nonwoven fabric 10 is a single sheet body in which the two layers are integrated.

  Although the nonwoven fabric of the present invention may have various surface shapes such as an uneven surface, like the nonwoven fabric 10 of the present embodiment shown in FIG. 1, both sides 10A and 10B (the surface of the fiber layer 1 and the fiber layer 2 Is preferably flat. The nonwoven fabric 10 is a laminate of a plurality of fiber layers and has a flat shape on both sides, so that both the smoothness of the surface and the cushioning feel are excellent, and the nonwoven fabric 10 is excellent. The flat shape refers to a material having a thickness difference of 1 mm or less between the concave portion and the convex portion on the surface of the nonwoven fabric. Specifically, the nonwoven fabric is cut in the thickness direction with a razor blade, and a photograph of a cross section is taken using a microscope (manufactured by Keyence Corporation, VHX-900). In the photograph, the thickness of the portion where the upper surface of the nonwoven fabric is located at the uppermost position, ie, the convex portion, and the portion where the upper surface of the nonwoven fabric is located at the lowermost position, ie, the thickness of the concave portion, are obtained by calculating the thickness difference. Can be Take the average of the three points.

  The nonwoven fabric 10 has at least one fiber layer 8 having a fiber mass 7. Hereinafter, the fiber layer 8 having the fiber lump 7 is referred to as a fiber lump layer 8. In FIG. 1, the fiber lump layer 8 is arranged on the fiber layer 1.

  In the present invention, the “fiber lump” refers to a node (a lump of yarn) formed by entanglement of fibers in a fiber layer. In the fiber mass portion, the density of the fiber is higher than that of the peripheral portion in the same fiber layer, and the density (brightness) of the color (mainly white) of the fiber is higher than that of the peripheral portion (granularity). ). The shape of the fiber mass is not particularly limited. In the present invention, the fiber mass has a flat shape crushed in the thickness direction of the nonwoven fabric in a cross section in the thickness direction of the nonwoven fabric, and preferably has a structure in which the surface of the fiber mass portion on the surface side of the nonwoven fabric is smooth. Thereby, the surface of the nonwoven fabric corresponding to the position where the fiber mass 7 is present becomes smooth, and the surface feel of the nonwoven fabric 10 is felt to be more excellent.

  The “fiber lump layer 8” refers to a layer having one or more fiber lump portions. The fiber lump layer 8 does not need to be filled with the fiber lump 7 and is preferably dispersed.

  The fiber lump layer 8 is not limited to the fiber layer 1 as shown in FIG. 1, but may be in the fiber layer 2 instead of the fiber layer 1 or in both layers. From the viewpoint of soft touch, it is preferable that any one layer be present. From the viewpoint of enhancing the visual effect of the pattern of the fiber lump 7 when the nonwoven fabric 10 is viewed in a plan view, it is preferable that both layers have the fiber lump layer 8. As a result, the pattern formed by the fiber clumps 7 appears to be dispersed not only in the plane direction but also in the thickness direction of the nonwoven fabric 10, and the concentration of the fiber clumps 7 seen in the thickness direction changes thinly as it is located on the lower layer side. You can see and see deeper patterns. When the fiber lump layer 8 is provided in both the fiber layer 1 and the fiber layer 2, it is preferable that the fiber lump 7 of the fiber layer 1 and the fiber lump 7 of the fiber layer 2 are arranged so as not to overlap in the thickness direction. The fiber lump layer 8 may be disposed on the entire fiber layer (fiber layer 1 or fiber layer 2) on which the fiber lump layer 8 is disposed, or may be disposed on a part thereof.

  As described above, the nonwoven fabric 10 is formed by fusing fibers at the layer interface in an entire region where the fiber layer 1 and the fiber layer 2 are in contact with each other and integrated. Therefore, even when the nonwoven fabric 10 includes the fiber lump layer 8 having the fiber lump 7, the entire nonwoven fabric 10 in which a plurality of fiber layers are integrated at the entire layer interface is felt to be thick, and the bulk and soft touch are felt. And it will be excellent. Then, when the nonwoven fabric 10 is viewed in a plan view, a pattern is provided by the difference in the shade of color between a portion having a fiber lump and a portion having no fiber lump. The nonwoven fabric 10 is provided with aesthetics by the pattern of the fiber lump 7, particularly the pattern of the fiber lump 7 having a flattened thickness.

  The nonwoven fabric 10 of the present 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 larger than the fine fibers. Thereby, the improvement of the soft touch of the nonwoven fabric by the fine fibers and the improvement of the bulkiness by the thick fibers can be compatible. Further, by having thick fibers, it is possible to contribute to improvement of the thickness recovery of the nonwoven fabric after pressurization, which is preferable.

  In addition, it is preferable that the fiber lump layer 8 contains the fine fibers. In this case, the fine fibers may be contained in the fiber lump 7 or may be contained in a portion other than the fiber lump 7. Thereby, the hardness around the fiber mass 7 felt when the nonwoven fabric 10 is touched is reduced by the presence of the fine fibers. In this case, in the nonwoven fabric 10, the fiber layer 1 having the fiber lump layer 8 containing the fine fibers is preferably arranged toward the skin contact surface side of the absorbent article.

  The fiber diameter of the fine fiber is more preferably 2 dtex or less, and further preferably 1.5 dtex or less, from the viewpoint of improving the soft touch of the nonwoven fabric 10. The fiber diameter of the fine fibers is more preferably 1 dtex or more, and further preferably 1.2 dtex or more, from the viewpoint of the spinning property of the card machine in the production of the nonwoven fabric. Specifically, the fiber diameter of the fine fiber is preferably from 1 dtex to 2 dtex, more preferably from 1.2 dtex to 1.5 dtex.

  The content of the fine fibers in the fiber mass layer 8 is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 100% by mass, from the viewpoint of improving the soft touch of the nonwoven fabric 10 as a mass ratio.

  In addition, the nonwoven fabric 10 of the present embodiment preferably has at least one fiber layer 9 having no fiber clump portion 7 (hereinafter, referred to as a non-fiber clump layer 9), in addition to the fiber clump layer 8 described above. For example, as shown in FIG. 1, there is a form in which the fiber layer 1 is a fiber lump layer 8 and the fiber layer 2 is a non-fiber lump layer 9.

  When the nonwoven fabric 10 has the fiber lump layer 8 and the non-fiber lump layer 9, it may have a thick fiber having a fiber diameter of more than 2.2 dtex and 7 dtex or less and a fine fiber having a smaller fiber diameter than the thick fiber. preferable. The fiber diameter of the fine fiber is preferably in the above range. Thereby, the improvement of the soft touch of the nonwoven fabric by the fine fiber and the improvement of the bulkiness by the thick fiber can be compatible, and can contribute to the improvement of the thickness recovery of the nonwoven fabric after pressurization, which is preferable.

  In addition, it is preferable that the non-fiber lump layer 9 includes the thick fibers. When the non-fiber lump layer 9 contains the thick fibers, the bulkiness can be improved and a cushion feeling can be imparted. In this case, the nonwoven fabric 10 is preferably such that the fiber layer 2 having the non-fiber lump layer 9 containing thick fibers is arranged toward the non-skin contact surface side of the absorbent article.

  The fiber diameter of the thick fiber is more preferably more than 2.2 dtex, and more preferably 4.4 dtex or more, from the viewpoint of improving the bulkiness and compression recovery of the nonwoven fabric 10. Further, the fiber diameter of the thick fiber is preferably 5.5 dtex or less, more preferably 5 dtex or less, from the viewpoint of the feeling from the fiber lump layer side. Specifically, the fiber diameter of the thick fiber is preferably more than 2.2 dtex and 5.5 dtex or less, more preferably 4.4 dtex or more and 5 dtex or less.

  The content of the thick fiber in the non-fiber lump layer 9 is preferably 50% by mass or more, more preferably 80% by mass or more, and more preferably 100% by mass, from the viewpoint of improving the bulkiness and compression recovery of the nonwoven fabric 10 as a mass ratio. % Is more preferred.

  In addition, the content of the thick fibers in the fiber lump layer 8 is preferably 50% by mass or less, more preferably 30% by mass or less, and more preferably 10% by mass or less in terms of mass ratio, from the viewpoint of improving the soft touch of the nonwoven fabric 10. Is more preferred.

(Method of measuring fiber diameter of fine fiber and thick fiber, method of measuring content of fine fiber in fiber lump layer 8, measurement method of content of thick fiber in non-fiber lump layer 9)
From any place of the nonwoven fabric, the fiber lump layer side and the non-fiber lump layer surface side are observed at three magnifications at 100 magnification using a scanning electron microscope (JCM-5100 manufactured by JEOL Ltd.).
Fiber diameter: 1 mm Measure the fiber diameter within a ² area range. The fiber diameter is measured at 20 points for each different fiber at one location, and the average value is defined as each fiber diameter. In addition, the fluctuation width of the fiber diameter in the nonwoven fabric for an absorbent article is usually such a small difference that it is difficult to confirm even when observed with the above-mentioned scanning electron microscope. For example, generally, the fluctuation width of the fiber diameter is about 6% according to the fiber standard. Therefore, each fiber diameter can be used as long as the average value is obtained by measuring 20 points as described above.
Fiber content: An OHP film is placed on a photograph within 1 mm ² enlarged and observed previously, and blacked out according to fiber diameter. This sheet is subjected to image analysis processing using image analysis software (NexusNewQube). Binarization processing is performed to determine the area. The area of each fiber is measured, and the ratio is defined as the content of each fiber.

(Measurement member sampling method)
In the above measurement, when a constituent member (for example, a surface material) to be measured is taken out from the absorbent article and evaluated and measured, it is obtained by the following method. That is, when the constituent member is fixed to another constituent member with an adhesive or the like, the adhesive is cooled by liquid nitrogen to facilitate peeling of the constituent member. When the component is fixed to another component by fusion or the like, the component is peeled off by hand, or the fusion portion is cut off with a cutter knife or the like and peeled off. This method is similarly used in other measurement methods.

  In the nonwoven fabric 10, the average fiber diameter of the non-fiber lump layer 9 is preferably larger than that of the fiber lump layer 8. Thereby, the fiber lump layer 8 becomes a layer for improving the soft touch of the nonwoven fabric 10, and the non-fiber lump layer 9 becomes a layer for improving the bulkiness and the thickness recovery of the nonwoven fabric 10. As a result, the fiber lump layer 8 and the non-fiber lump layer 9 can share the function of the non-woven cloth 10 in units of layers, and both layers cooperate in the thickness direction to improve the texture of the entire non-woven cloth 10. It can be. In this regard, it is preferable that the nonwoven fabric 10 has the fine fibers and the thick fibers, and the fiber lump layer 8 includes the fine fibers, since the action can be more clearly exhibited. In addition, it is more preferable that the non-fiber lump layer 9 contains the thick fiber from the same viewpoint.

  The difference V3 (= V1−V2) between the average fiber diameter V1 of the non-fiber lump layer 9 and the average fiber diameter V2 of the fiber lump layer 8 is preferably more than 0 dtex from the viewpoint of the above-mentioned function sharing in the nonwoven fabric, and is preferably 2.2 dtex. The above is more preferable, and 3dtex or more is further preferable. In addition, the difference V3 is preferably 5.6 dtex or less, more preferably 4 dtex or less, and still more preferably 3.5 dtex or less, from the same viewpoint as described above. Specifically, the difference V3 is preferably more than 0 dtex and not more than 5.6 dtex, more preferably not less than 2.2 dtex and not more than 4 dtex, further preferably not less than 3 dtex and not more than 3.5 dtex.

(Measurement method of average fiber diameter of fiber lump layer 8 and non-fiber lump layer 9)
The fiber obtained based on the above (method of measuring the fiber diameter of the fine fiber and the thick fiber, method of measuring the content of the fine fiber in the fiber lump layer 8, and measurement method of the content of the thick fiber in the non-fiber lump layer 9) The diameter is multiplied by the content, and the sum is defined as the average fiber diameter of each layer.

  In the nonwoven fabric 10, the basis weight of the non-fiber clump layer 9 is preferably larger than that of the fibrous clump layer 8. As a result, the non-fiber lump layer 9 becomes bulkier than the fiber lump layer 8, and the hardness of the fiber lump 7 becomes more difficult to perceive. In addition, the bulkiness of the non-fiber lump layer 9 acts to enhance the cushioning property of the entire nonwoven fabric 10, and further reduces the stress applied to the skin by the fiber lump 7 when the fibrous lump layer 8 is crushed in the thickness direction. As a result, good texture can be further improved. Along with this difference in basis weight, it is preferable that the nonwoven fabric 10 has the fine fibers and the thick fibers, and that the fiber lump layer 8 contains the fine fibers, since the above-mentioned action can be more clearly exhibited. In addition, it is more preferable that the non-fiber lump layer 9 contains the thick fiber from the same viewpoint. Furthermore, the nonwoven fabric 10 preferably has a larger average fiber diameter in the non-fiber clump layer 9 than in the fibrous clump layer 8.

  The difference Y3 (= Y1−Y2) between the basis weight Y1 of the non-fiber lump layer 9 and the basis weight Y2 of the fibrous lump layer 8 is 0 g / m2 from the viewpoint of improving the cushioning property of the entire nonwoven fabric and improving the feeling.²Super preferred, 3 g / m²More preferably, 5 g / m²The above is more preferred. The difference Y3 is 20 g / m2 from the viewpoint of improving the texture.²The following is preferable, and 15 g / m²The following is more preferred, and 10 g / m²The following are more preferred. The difference Y3 is specifically 0 g / m²Super 20g / m²The following is preferred, 3 g / m²More than 15g / m²The following is more preferred, and 5 g / m ²More than 10g / m²The following are more preferred.

(Method of measuring basis weight of fiber lump layer 8 and non-fiber lump layer 9)
1) The value obtained by converting the mass of the nonwoven fabric to be measured per 1 m ^{2 is} defined as the total basis weight.
The mass (w) of the nonwoven fabric to be measured is measured, and the value calculated by the following equation is defined as the total basis weight (W).
W = (1,000,000 / LMD / LCD) w = 25w
LMD: length in the MD direction of the nonwoven fabric to be measured 250 mm
LCD: 160mm in the CD direction of the nonwoven fabric to be measured
If you can not collect in the size when taking samples from the product cuts within the range that can be harvested and converted per 1 m ^2.
2) Basis weight of each layer: Each layer of the nonwoven fabric to be measured is carefully peeled off, and the value obtained by converting the mass per 1 m ^{2 is} defined as the basis weight of each layer.
[Unit: Number of digits] g / m ² : Calculate to the first decimal place by rounding off the second decimal place.
[Number of Measurements] Three points are measured, and the average value is defined as each grammage.

The basis weight of the entire nonwoven fabric 10 is preferably 15 g / m ² or more from the viewpoint of having excellent bulkiness and soft touch and having good texture in a structure in which two or more fiber layers are laminated and integrated. Preferably, it is 18 g / m ² or more, more preferably 20 / m ² or more. The basis weight of the entire nonwoven fabric 10, from the viewpoint of spinning ability of the nonwoven fabric production, preferably 40 g / ^{m 2} or less, more preferably 30 g / ^{m 2} or less, 25 g / ^{m 2} or less is more preferable. The basis weight of the entire nonwoven fabric 10, specifically, preferably from 15 g / ^{m 2} or more 40 g / ^{m 2} or less, 18 g / ^m, more preferably ² or more 30 g / ^{m 2} or less, 20 / ^{m 2} or more 25 g / ^{m 2} or less Is more preferred. The basis weight of the entire nonwoven fabric 10 is measured according to the above-mentioned (method of measuring the basis weight of the fiber lump layer 8 and the non-fiber lump layer 9).

With respect to such a nonwoven fabric 10, the thickness of the nonwoven fabric 10 measured at a pressure of 7.64 kpa at the position where the fiber lump 7 is disposed is defined as T1, and at the position where the fiber lump 7 is not disposed under the same pressure. Assuming that the thickness of the nonwoven fabric 10 measured in the above is T2, the smaller the difference T3 in the thickness defined by T3 = T1−T2, the harder it is to perceive the hardness caused by the fiber mass 7. As a result, a cushion feeling accompanying bulkiness due to the lamination of a plurality of fiber layers is easily felt, and soft touch is easily perceived. In this respect, the thickness difference T3 is preferably equal to or less than 0.4 mm, more preferably equal to or less than 0.3 mm, still more preferably equal to or less than 0.2 mm, and most preferably 0 (zero) mm.
Here, the “position where the fiber mass portion is disposed” refers to the position of the fiber mass portion 7 on the surface of the nonwoven fabric 10 when viewed in plan from the surface on the pressing side of the front and back surfaces of the nonwoven fabric 10. Refers to a position at which the presence can be confirmed (hereinafter, the meaning is the same in the present specification). Further, the “position where the fiber lump portion is not arranged” means a position where the presence of the fiber lump portion 7 cannot be visually confirmed on the plane viewed from above (hereinafter, the same meaning in the present specification). ).

(Method of measuring thickness of nonwoven fabric under 7.64 kPa pressure)
Using a dial gauge thickness gauge (JIS B7503 (1997), UPAIGHT DIAL GAUGE 7.64 kPa pressure manufactured by PEACOCK Co., Ltd.) The thickness of the nonwoven fabric at the position where the fiber mass is arranged is measured using a flat disk with a Φ5 mm tip. At T1, the thickness T2 at the position where the fiber lump portion is not arranged in the nonwoven fabric under the same pressure is measured, and the thickness difference defined by T3 = T1−T2 is obtained. The measurement is performed at five or more points for T1 and T2. Then, the average value of T1 and the average value of T2 are calculated, and the difference between them is defined as T3. The load of 7.64 kpa is a measurement condition set in order to clarify the existence of the fiber mass.

The soft touch of the nonwoven fabric 10 is indicated by the value of the average friction coefficient, and the smaller the value, the better the touch. In general, the value of the average friction coefficient is smaller in a portion where the fiber mass 7 is not arranged than in a portion where the fiber mass 7 is arranged. However, the nonwoven fabric 10 of the present embodiment is formed by laminating a plurality of fiber layers in the thickness direction and integrating them, and the average friction coefficient is reduced at the position where the fiber mass 7 is disposed. The average coefficient of friction (Q1) at the position where the fiber mass 7 of the nonwoven fabric 10 is arranged is preferably 2.5 or less, more preferably 2.4 or less, and further preferably 2.3 or less, from the viewpoint of maintaining soft touch. Preferably, 1.6 or more is realistic. Specifically, the average friction coefficient (Q1) at the position where the fiber mass 7 of the nonwoven fabric 10 is arranged is preferably 1.6 or more and 2.5 or less, more preferably 1.6 or more and 2.4 or less. More preferably, it is from 0.6 to 2.3.
The difference Q3 (= Q1-Q2) between the average friction coefficient Q1 at the position where the fiber mass 7 of the nonwoven fabric 10 is arranged and the average friction coefficient Q2 at the position where the fiber mass 7 of the nonwoven fabric 10 is not arranged is: From the viewpoint of maintaining soft touch, it is preferably 0.7 or less, more preferably 0.5 or less, still more preferably 0.32 or less, particularly preferably 0.3 or less, and most preferably 0 (zero).

(Method of measuring average friction coefficient)
Using a KES-FB4 surface tester manufactured by Kato Tech Co., Ltd., the nonwoven fabric to be measured is cut into a 15 cm square, and the fiber mass portion is arranged on the measurement surface under the conditions of SENS: 2 × 5, load 4.9 kPa. The MIU value at the set position and at the position where the fiber mass portion is not arranged is measured. The measurement is performed at five or more points in each of two orthogonal directions (typically, the MD direction and the CD direction), and the average value is obtained. The MIU value is an average friction coefficient. The larger the value, the worse the surface is rough and the texture is poor. The smaller the MIU value, the smoother the texture and the better the texture.

  The above-mentioned fiber mass layer 8 is preferably the outermost layer of the nonwoven fabric 10. In this case, the fiber lump layer 8 may be provided only on one of the front and back surfaces of the nonwoven fabric 10 or the fiber lump layer 8 may be provided on both the front and back surfaces of the nonwoven fabric 10. Since the fiber mass layer 8 is the outermost layer of the nonwoven fabric 10, the visual effect is maximized.

From the viewpoint of maintaining the soft touch of the nonwoven fabric 10, the number of the fiber mass portions 7 disposed on the nonwoven fabric 10 is 10 cm square when the front and back surfaces of the nonwoven fabric 10 are viewed in plan (in a plan view in a state where the respective fiber layers are stacked). Is preferably 50 or less, more preferably 40 or less, and even more preferably 30 or less. On the other hand, from the viewpoint of providing a pattern, the number of fiber lump portions 7 arranged on the nonwoven fabric 10 is a 10 cm square area when the front and back surfaces of the nonwoven fabric 10 are viewed in a plan view (in a plan view in a state where the respective fiber layers are stacked). The average for each is preferably 5 or more, more preferably 10 or more, and even more preferably 20 or more. The number of the fiber mass portions 7 is, specifically, an average of 5 or more and 50 or less for each 10 cm square area when the front and back surfaces of the nonwoven fabric 10 are viewed in a plan view (in a plan view in a state where the respective fiber layers are stacked). It is preferably from 10 to 40, more preferably from 20 to 30.
In addition, from the viewpoint of reducing the chance of contact between the skin and the fiber lump 7, the number of the fiber lump 7 in the fiber layer on the skin side of the absorbent article in the laminated fiber layers is The average of each side of the fiber layer on a 10 cm square area in plan view is preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. The number of fiber lump portions 7 in the fiber layer on the skin side of the absorbent article is preferably one or more. The number of fiber clumps 7 in the fiber layer on the skin surface side of the absorbent article is, specifically, an average of 1 to 30 or less as an average for each area of 10 cm square in a plan view of the fiber layer on the skin surface side. Is preferably 1 or more and 20 or less, more preferably 1 or more and 10 or less.
Further, from the viewpoint of forming a deep pattern, the number of fiber clumps 7 arranged in the fiber layer on the non-skin surface side of the absorbent article is the non-skin surface side of the two laminated layers. As an average for each area of 10 cm square in a plan view of the fiber layer, 3 or more is preferable, 8 or more is more preferable, and 15 or more is further preferable.

Individual fiber agglomerations portion 7 of the nonwoven fabric 10 when viewed in plan size (area), from the viewpoint of maintaining the soft touch of the nonwoven fabric 10 is preferably 10 mm ² or less, 8 mm ² or less, more preferably, is 6 mm ² or less More preferred. On the other hand, the magnitude of the time of the nonwoven fabric 10 of the individual fiber agglomerations unit 7 viewed from above, from the viewpoint of imparting a pattern, preferably 1 mm ² or more, more preferably 2.5 mm ² or more, 4 mm ² or more is more preferable. Size when viewed from above the nonwoven fabric 10 of the individual fiber agglomerations section 7 (area), specifically, preferably 1 mm ² or more 10 mm ² or less, more preferably 2.5 mm ² or more 8 mm ² or less, 4 mm ² or 6 mm ² or less is more preferable.
The size of the time of the nonwoven fabric 10 of the fiber mass portion 7 disposed in the fiber layer to be a skin face side of the absorbent article is viewed in plane is preferably 9 mm ² or less, more preferably 7 mm ² or less, 5 mm ² or less Is more preferred.
Further, from the viewpoint of forming a deep pattern, the size of the nonwoven fabric 10 of the fiber lump 7 arranged in the fiber layer on the non-skin side of the absorbent article among the two laminated layers when viewed in plan. Saga, 2 mm ² or more, more preferably 3 mm ² or more, 5 mm ² or more is more preferable.

The size (thickness) of the individual fiber mass portions 7 in the thickness direction of the nonwoven fabric 10 is preferably 50% or less, more preferably 40% or less, as a percentage of the thickness of the nonwoven fabric 10 from the viewpoint of maintaining the soft touch of the nonwoven fabric 10. It is preferably at most 30%. On the other hand, the size (thickness) of the individual fiber mass portions 7 in the thickness direction of the nonwoven fabric 10 is preferably as small as possible within a range of more than 0% as a percentage of the thickness of the nonwoven fabric 10 from the viewpoint of the feeling. Specifically, the size (thickness) of the individual fiber mass portions 7 in the thickness direction of the nonwoven fabric 10 is preferably more than 0% and not more than 50%, more preferably more than 0% and not more than 40% as a ratio to the thickness of the nonwoven fabric 10. Is more preferable, and more than 0% and 30% or less is still more preferable.
In addition, from the viewpoint of reducing the hardness felt when the skin touches the fiber lump portion 7 with the plurality of laminated fiber layers, the fiber of the two layers laminated on the skin surface side of the absorbent article The size in the thickness direction of the nonwoven fabric 10 of the fiber lump 7 arranged in the layer is preferably 50% or less, more preferably 40% or less, and still more preferably 30% or less, as a percentage of the thickness of the nonwoven fabric 10.
Furthermore, the size (thickness) of the individual fiber mass portions 7 in the thickness direction of the nonwoven fabric 10 is preferably 1 mm or less, more preferably 0.8 mm or less, still more preferably 0.5 mm or less, from the same viewpoint as described above. Further, it is more preferable that the diameter is smaller than 0 mm. Specifically, the size (thickness) of the individual fiber mass portions 7 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 further preferably greater than 0 mm and 0.5 mm or less. preferable.

(Method of measuring the number, area and thickness of fiber mass)
A photograph is taken using a microscope (manufactured by Keyence Corporation, VHX-900) from the observation target surface of the nonwoven fabric cut into a 10 cm square (for example, surface 10A in nonwoven fabric 10). The image data (jpeg) is subjected to image analysis processing using image analysis software (NexusNewQube). A binarization process is performed to determine the number and area of the lumps. Further, the entire lump is cut in the thickness direction with a razor blade, and the cross section is observed with the microscope to measure the thickness of the nonwoven fabric and the thickness of the fiber lump.

The air-through nonwoven fabric for an absorbent article of the present invention is used as a component of an absorbent article. Examples of the absorbent articles include various articles having a function of absorbing and retaining human excreted liquid, such as diapers, sanitary napkins, urine absorbing pads, and panty liners.
The air-through nonwoven fabric for an absorbent article of the present invention is used as various members of the absorbent article according to its function, and is incorporated into the absorbent article. For example, when it has liquid permeability, it is incorporated as a topsheet, and when it has water repellency, it is incorporated as a sidesheet. Moreover, it is made thinner and softer, and is incorporated as an exterior material for improving the feel on the outside (clothing side) of an absorbent article such as a diaper.
Among them, the air-through non-woven fabric for absorbent articles of the present invention has an absorption property from the viewpoint of facilitating the feel of the non-woven fabric excellent in bulk and soft touch with the skin, and facilitating visual recognition of the pattern of the non-woven fabric. It is preferable to arrange the outermost layer on the skin side of the sexual article and arrange the fiber lump layer 8 toward the skin side. For example, a surface sheet and a side sheet are mentioned, and it is particularly preferable to arrange the air-through nonwoven fabric for an absorbent article of the present invention on the absorbent article as the surface sheet.

  Next, a preferred embodiment of the method for producing an air-through nonwoven fabric for absorbent articles of the present invention will be described. Here, a method for manufacturing the nonwoven fabric 10 of the above embodiment will be described. However, the fiber layers to be laminated are not limited to two layers (the fiber layer 1 and the fiber layer 2), and may be a layer in which three or more fiber layers are laminated.

The manufacturing method of this embodiment includes the following steps 501 and 502.
Step 501: a fiber-spreading step of performing a fiber-spreading process on thermoplastic fibers a plurality of times to form a web.
Step 502: a step of laminating a plurality of single-layer webs obtained in the opening step to form a laminated web, and subjecting the laminated web to air-through processing with hot air to obtain an air-through nonwoven fabric.

In addition, the manufacturing method of the present embodiment includes the following step 503.
Step 503: a calendering step of using one pair of calender rolls for one or more selected from the single-layer web, the laminated web, and the air-through nonwoven fabric.
Step 503 is performed after step 501, before step 502, during step 502, and / or after step 502.

FIG. 2 shows a manufacturing apparatus 100 suitably used in the method for manufacturing the nonwoven fabric 10 of the present embodiment. The production apparatus 100 is obtained by carding, from the upstream side to the downstream side, the fiber-spreading units 101 and 102 of the fiber material amount used as the raw material of the nonwoven fabric, the carding units 103 and 104 forming the fiber web. The apparatus includes a laminated web forming section 105 for conveying and laminating a single-layer web, a web calender section 106 for performing a pressure treatment on the laminated web, and a heat treatment section (air through processing section) 107.
In the manufacturing apparatus 100, the step 501 is performed in the opening units 101 and 102 and the carding units 103 and 104. The step 502 is performed in the laminated web forming unit 105 and the heat treatment unit 107.
In the manufacturing apparatus 100, the step 503 is performed in the web calender unit 106. The web calender section 106 is disposed between the laminated web forming section 105 and the heat treatment section 107, and performs the step 503 as web calendering of the laminated web in the middle of the step 502.

  Each of the opening units 101 and 102 has a device for opening thermoplastic fibers serving as a raw material of the fiber layers 1 and 2 and sending the opened thermoplastic fibers to the next carding units 103 and 104, respectively. In the case of using the fine fibers and the thick fibers having the specific fiber diameters described above, it is preferable to open the fibers separately for the fine fibers and the thick fibers. In FIG. 2, a raw fiber (thin fiber) 71 is input to the opening unit 101 to open the fiber (arrow 171), and a raw fiber (thick fiber) 72 is input to the opening unit 102 to open the fiber (arrow). 172).

  As the raw fiber (fine fiber) 71 and the raw fiber (thick fiber) 72, various thermoplastic fibers used for the air-through nonwoven fabric can be used. For example, a composite fiber having a core-sheath structure in which the resin component of the sheath has a lower melting point than that of the resin component of the core may be used.

  The carding portions 103 and 104 receive the fibers spread in the fiber spreading portions 101 and 102, respectively (arrows 173 and 174), and form single-layer webs 81 and 82. Specifically, the aggregate of the fibers spread in the fiber-spreading units 101 and 102 is combed and further spread to form a sheet-like web. The carding section 103 forms a single layer web 81 based on the raw fibers (fine fibers) 71, and the carding section 104 forms a single layer web 82 based on the raw fibers (thick fibers) 72.

  In the carding sections 103 and 104, various card machines generally used for manufacturing an air-through nonwoven fabric can be used without any particular limitation. For example, a parallel card machine, a semi-random card machine, a random card machine, a parallel card machine combined with a cross layer and a drafter, and the like can be mentioned. In addition, the card machine includes one provided with three types of rolls of a main cylinder roll, a worker roll, and a stripper roll covered with a saw-toothed metallic wire. The fiber aggregate can be broken between the main cylinder roll, the worker roll, and the stripper roll to perform fiber opening. By arranging a plurality of pairs of worker rolls and stripper rolls with respect to the main cylinder roll, it is possible to perform the fiber opening process a plurality of times in each of the carding units 103 and 104 in the card machine.

  As described above, both of the opening units 101 and 102 and the carding units 103 and 104 perform the opening operation a plurality of times.

  In the manufacturing method of the present embodiment, a spreading step of forming a web by applying a plurality of spreading processes to the thermoplastic fibers in the above-described opening sections 101 and 102 and carding sections 103 and 104 (step 501). I do.

Next, in the laminated web forming section 105, the laminated web 90 is formed by laminating the single-layer web 82 formed in the carding section 104 on the single-layer web 81 formed in the carding section 103.
Specifically, the single-layer web 81 is carried out from the carding section 103 along the carry-out belt 103A and is placed on the carrying belt 105A. The transport belt 105A transports the single-layer web 81 downstream. In addition, the single-layer web 82 is carried out from the carding along the carry-out belt 104A, guided to the transport belt 105A, and stacked on the single-layer web 81 being transported. The laminated web 90 thus formed is transported further downstream along the transport belt 105A. In the laminated web 90, portions corresponding to the single-layer webs 81 and 82 are simply referred to as webs 81 and 82.

  In the laminated web 90, the web 82 is formed from raw fibers (thick fibers) 72, and the web 81 is formed from raw fibers (fine fibers) 71. Therefore, the average fiber diameter of the web 82 is larger than the average fiber diameter of the web 81. From this, the web 81 becomes the fiber mass layer 8 containing the fine fibers having the specific fiber diameter in the completed nonwoven fabric 10. The web 82 can be the non-fiber lump layer 9 containing the thick fibers having the specific fiber diameter in the completed nonwoven fabric 10. In addition, increasing the basis weight of the non-fibrous lump layer 9 in the completed nonwoven fabric 10 compared to the fibrous lump layer 8 can reduce the supply mass of the fiber from the spreader 102 to the carding unit 104 from the spreader 101. This can be realized by increasing the supply mass of the fiber to the carding portion 103.

Thus, in the manufacturing method of the present embodiment, it is preferable to form a laminated web using a plurality of types of fibers having different fiber diameters. In particular, it is more preferable to use different fiber diameters for the web 82 and the web 81.
As the fibers having different fiber diameters, it is preferable that the above-mentioned fine fibers having a fiber diameter of 1 dtex or more and 2.2 dtex or less are used. Further, the fiber diameter of the fine fiber is more preferably in the range of the fiber diameter described above.

  The web calender 106 performs web calendering by pressing the conveyed laminated web 90 between a pair of calender rolls 106A and 106B (hereinafter, may be simply referred to as “calendering”). This makes it possible to smooth the web surface at a certain portion of the fiber lump 7 and reduce the hardness of the fiber lump 7.

  In particular, in the production method of the present embodiment, since the laminated web 90 before being formed into a nonwoven fabric is subjected to calendering, the fibers are not yet fixed by fusion, and the fibers can be largely moved. . That is, in the calendering according to the present embodiment, there is no possibility that the fibers are separated or broken at the fused portion of the fibers, and the fibers gathering in the fiber lump 7 are preferably separated while maintaining the state of the fibers in a good state. (The distance between the fibers is widened), and the fiber lump 7 can be satisfactorily crushed. Thereby, the effect of reducing the hardness of the fiber mass 7 is enhanced. Further, in the thickness direction by calendering, the fibers of the fiber lump 7 are easily separated from each other in any of the laminated webs 81 and 82 before forming the nonwoven fabric, and the fiber lump 7 (Hereinafter, a laminated web subjected to web calendering may be referred to as a laminated web 95). Further, in a series of manufacturing steps, by performing an air-through process described later after the calendering process, the air-through process can be used as a process for recovering the thickness of the nonwoven fabric. That is, in the present embodiment, the processing steps performed in this order are significant for recovering the thickness of the laminated web 95, forming a bulkier and softer touch, and forming a pattern.

In the heat treatment unit 107, the laminated web 95 subjected to the web calendering is subjected to air through processing by hot air.
Specifically, the heat treatment section 107 has a hood 107A and a conveyor belt 107B provided with a gas permeable net that circulates in the hood 107A. In the hood 107A, hot air is blown from above toward the conveyor belt 107B (arrow F shown in FIG. 2). In the conveyor belt 107B, the blown hot air blows through the air permeable net. The web 95 subjected to web calendering is extruded to the heat treatment unit 107 by the rotation of the roll of the web calender unit 106. In the heat treatment unit 107, the laminated web 95 is transported into the hood 107A by the conveyor belt 107B. Hot air heated to a predetermined temperature is blown from above the laminated web 95 (that is, from above the web 82) to the laminated web 95 in the hood 107A by a penetration method. That is, air through processing is performed on the laminated web 95. Thereby, in the laminated web 95, the interval between the fibers in the fiber lump 7 is widened by the web calendering process described above, and the intersection of the fibers is blown by blowing hot air in a fiber state in which the hardness of the fiber lump 7 is relaxed. Are fused. Thereby, the air-through nonwoven fabric 10 for an absorbent article of the present embodiment is obtained.

As described above, in the manufacturing method of the present embodiment, the single-layer webs 81 and 82 obtained through the opening step of the step 501 are subjected to the laminating web forming section 105, the web calender section 106, and the heat treatment section 107. Step 502 and Step 503 are performed. Specifically, a process 502 by the laminated web forming unit 105 and the heat treatment unit 107 and a calendering process (process 503) by the web calender unit 106 on the way are performed.
By performing these steps 501, 502, and 503, the above-described air-through nonwoven fabric 10 for an absorbent article of the present embodiment can be accurately manufactured. That is, even if the fiber layer 8 having the fiber lump 7 is included, the air-through nonwoven fabric 10 for an absorbent article having a pattern that is excellent in bulkiness and soft touch and has a pattern can be manufactured with high accuracy. The manufactured air-through nonwoven fabric 10 for an absorbent article is wound into a roll as required.

  In the manufacturing method of the present embodiment, the calendering step (step 503) is performed on the laminated web 90 before the air-through processing. However, the present invention is not limited thereto, and the single-layer web 81 and the single-layer web 82 before lamination may be individually calendered, or the air-through nonwoven fabric after the air-through processing may be calendered. . When calendering is performed on the air-through nonwoven fabric, the air-through nonwoven fabric to be processed is a raw material air-through nonwoven fabric before becoming the air-through nonwoven fabric 10 for an absorbent article of the present embodiment.

In the manufacturing method of the present embodiment, when the calendering step (step 503) is performed, the fiber lump 7 is crushed by the calender, and portions other than the fiber lump 7 are smoothed and smoothed by calendering. . Since the nonwoven fabric 10 having a smooth surface is integrated while maintaining the thickness of the plurality of fiber layers, the thickness and the cushion are such that the feeling of foreign matter (discomfort) that touches the skin of the fiber mass 7 is reduced. It will have the nature.
In addition, in the manufacturing method of the present embodiment, the fiber mass can be crushed in a consistent manufacturing process of the nonwoven fabric. Therefore, it is not necessary to introduce a fiber lump inspection device after the production of the nonwoven fabric, and the production cost can be reduced. Further, since the post-manufacturing inspection process, the post-calendering process, and the hot-air recovery process are not required, the production efficiency of the nonwoven fabric can be improved.

  From the viewpoint of effectively reducing the hardness of the fiber mass portion 7, the above calendering is preferably a web calendering performed on one or a plurality of webs selected from a single-layer web or a laminated web.

  The calendering is not limited to being performed in only one of the single-layer web stage, the laminated web stage, and the air-through nonwoven fabric stage, but may be performed in two or more stages. Further, the calendar processing is not limited to being performed once in each stage, but may be performed two or more times. For example, the present invention is not limited to the case where the calendar processing is performed only once on the laminated web 90, and may be performed two or more times.

  The linear pressure in the calendering process, that is, the linear pressure applied to the laminated web 90, the single-layer webs 81 and 82, and the air-through nonwoven fabric (raw air-through nonwoven fabric) sandwiched by the calender rolls 106A and 106B increases the single-layer web in all processes. Of the linear pressures applied by all the rolls on 81, 82, laminated webs 90, 95 and air-through nonwoven 601, the highest is preferred. The term "all rolls" as used herein means all rolls used in all manufacturing steps, in addition to the above-described calender rolls 106A and 106B. For example, a nip roll for conveying the nonwoven fabric after the heat treatment, a nip roll and a press roll for winding, and a press roll for slitting thereafter are applicable.

  In particular, in the calendering step, the linear pressure (P) applied to the single-layer webs 81 and 82 and the laminated web 90 is set to 20 N / p from the point of effectively reducing the hardness of the fiber mass 7 before heat fusion. cm or more, more preferably 100 N / cm or more, even more preferably 180 N / cm or more. In addition, the linear pressure (P) is preferably 700 N / cm or less, more preferably 500 N / cm or less, and further preferably 250 N / cm or less, from the viewpoint of the recovery of the thickness after pressing. Specifically, the linear pressure (P) is preferably from 20 N / cm to 700 N / cm, more preferably from 100 N / cm to 500 N / cm, even more preferably from 180 N / cm to 250 N / cm.

A pair of calender rolls 106A and 106B used in the web calender unit 106 are smooth rolls. Various materials used for calendering can be used as the material. Further, the material of the calendar roll 106A and the material of the calendar roll 106B may be the same or different.
Among them, the calender roll used for calendering is preferably a combination of a resin roll and a steel roll from the viewpoint of further increasing the effect of reducing the hardness of the fiber mass 7. In the web calendering process of the present embodiment, the calender roll 106 </ b> A is assumed to be in contact with the web 82 including the thick fiber of the laminated web 90, and the steel roll is used as the calender roll 106 </ b> B. A resin roll is used to abut on 81. However, the arrangement of the resin roll and the steel roll is not limited to this, and may be a reverse combination.

  The hardness of the resin roll is preferably 20 degrees or more, more preferably 50 degrees or more, and still more preferably 80 degrees or more in D hardness (JIS K6253-3) from the viewpoint of further enhancing the effect of reducing the hardness of the fiber mass 7. . From the same viewpoint as above, the hardness of the resin roll is preferably 100 degrees or less, more preferably 95 degrees or less, and further preferably 90 degrees or less in D hardness (JIS K6253-3). Specifically, the hardness of the resin roll is preferably from 20 to 100 degrees, more preferably from 50 to 95 degrees, and still more preferably from 80 to 90 degrees.

Further, the air-through processing preferably includes a plurality of air-through processings.
FIG. 3 shows an aspect of a heat treatment section (air through processing section) having a first air through processing section 117 and a second air through processing section 127. In this embodiment, the air through processing is performed twice, that is, the first air through processing and the second air through processing. However, the number of air-through processes is not limited to two in FIG. 3, but may be three or more. When the air-through processing includes three or more air-through processings, the “post-stage air-through processing” with respect to the “first air-through processing” means the second and subsequent air-through processings. In the two air-through processings shown in FIG. 3, “first air-through processing” is a first air-through processing, and “subsequent air-through processing” means a second air-through processing. In the air-through process (two air-through processes) shown in FIG. 3, hot air is blown on the hood 107C of the first air-through processing unit 117 (arrow F1), and hot air is blown on the hood 107D of the second air-through processing unit 127 (arrow). F2). At this time, the laminated web 95 subjected to the web calendering is continuously conveyed from the first air-through processing section 117 to the second air-through processing section 127 by the conveyor belt 107B. Thus, the first air-through processing and the second air-through processing are continuously performed on the laminated web 95.

  In the air-through process, it is preferable that the air velocity of the hot air is higher in the subsequent air-through processing than in the first air-through processing, that is, the initial air-through processing is performed at a low air velocity. Thereby, the collapse of the bulk due to the wind pressure in the air-through processing section is suppressed, the hot air recovery effect is exhibited, and the web becomes bulky. In particular, when calendering is performed on the laminated web 90 or the single-layer webs 81 and 82 before being formed into a nonwoven fabric as in the present embodiment, the above-described processing in the subsequent air-through processing is effective.

  Specifically, the wind speed S1 of the hot air in the first air-through processing is preferably 0.2 m / sec or more, more preferably 0.25 m / sec or more, and even more preferably 0.4 m / sec or more. The wind speed S1 of the hot air in the first air-through processing is preferably 1.2 m / sec or less, more preferably 0.8 m / sec or less, and even more preferably 0.5 m / sec or less. Specifically, the wind speed S1 is preferably from 0.2 m / sec to 1.2 m / sec, more preferably from 0.25 m / sec to 0.8 m / sec, and more preferably from 0.4 m / sec to 0.5 m / sec. / Sec or less is more preferable. Thereby, the collapse of the web is suppressed, and the effect of recovering the thickness is exhibited.

  The wind speed S2 of the hot air in the subsequent air-through processing is preferably 0.8 m / sec or more, more preferably 0.9 m / sec or more, and even more preferably 1.2 m / sec or more. The wind speed S2 of the hot air in the subsequent air-through processing is preferably 1.6 m / sec or less, more preferably 1.4 m / sec or less, and still more preferably 1.3 m / sec or less. Specifically, the wind speed S2 is preferably 0.8 m / sec or more and 1.6 m / sec or less, more preferably 0.9 m / sec or more and 1.4 m / sec or less, and 1.2 m / sec or more and 1.3 m or less. / Sec or less is more preferable. This allows air to penetrate the web evenly, effectively providing thermal energy, resulting in a nonwoven fabric structure.

  The difference S3 (= S2-S1) between the wind speed S1 of the hot air in the first air through process and the wind speed S2 of the hot air in the subsequent air through process is preferably more than 0 m / sec, more preferably 0.4 m / sec or more, and more preferably 0.4 m / sec or more. 8 m / sec or more is more preferable. The difference S3 (= S2-S1) between the wind speed S1 of the hot air in the first air-through process and the wind speed S2 of the hot air in the subsequent air-through process is preferably 1.4 m / sec or less, more preferably 1.2 m / sec or less, It is more preferably 1 m / sec or less. Specifically, the difference S3 (= S2-S1) between the wind speed S1 of the hot air in the first air-through process and the wind speed S2 of the hot air in the subsequent air-through process is preferably more than 0 m / sec and 1.4 m / sec or less, 0.4 m / sec or more and 1.2 m / sec or less are more preferable, and 0.8 m / sec or more and 1 m / sec or less are still more preferable. Thereby, both the recovery of the bulk and the nonwoven fabric can be effectively realized.

  Further, in the air through step, it is preferable that the temperature of the hot air is higher in the subsequent air through processing than in the first air through processing. As a result, the fusion of the fibers proceeds in a stepwise manner, whereby the recovery of the web in the air-through processing portion is effectively exhibited. In particular, when calendering is performed on the laminated web 90 or the single-layer webs 81 and 82 before forming the nonwoven fabric as in the present embodiment, the above-described effect in the subsequent air-through processing is higher.

  Specifically, the temperature P1 of the hot air in the first air-through treatment is preferably 85 ° C. or higher, more preferably 90 ° C. or higher, even more preferably 100 ° C. or higher. The temperature P1 of the hot air in the first air-through treatment is preferably 134 ° C. or lower, more preferably 115 ° C. or lower, and further preferably 105 ° C. or lower. Specifically, the temperature P1 of the hot air in the first air-through treatment is preferably from 85 ° C to 134 ° C, more preferably from 90 ° C to 115 ° C, and still more preferably from 100 ° C to 105 ° C. Thereby, the recoverability of the web in the air-through processing section can be effectively exhibited.

  The temperature P2 of the hot air in the subsequent air-through treatment is equal to or higher than the melting point of the component of the fiber surface used (for example, the sheath portion in the core-sheath composite fiber), preferably 145 ° C or lower, more preferably 137 ° C or lower, and 134. C. or lower is more preferable. More specifically, the temperature P2 of the hot air in the subsequent air-through treatment is preferably from the melting point of the component on the fiber surface to be used to 145 ° C or less, more preferably from the melting point of the component on the fiber surface to be used to 137 ° C or less. The temperature is more preferably from the melting point of the surface component to 134 ° C. As a result, it is possible to produce a nonwoven fabric having a good texture and a soft touch.

  The difference P3 (= P2-P1) between the temperature P1 of the hot air in the first air-through process and the temperature P2 of the hot air in the subsequent air-through process is preferably higher than 0 ° C., more preferably 20 ° C. or higher, and further preferably 30 ° C. or higher. . The difference P3 (= P2−P1) between the temperature P1 of the hot air in the first air-through processing and the temperature P2 of the hot air in the subsequent air-through processing is preferably 60 ° C. or lower, more preferably 40 ° C. or lower, even more preferably 35 ° C. or lower. . Specifically, the difference P3 (= P2-P1) between the temperature P1 of the hot air in the first air-through processing and the temperature P2 of the hot air in the subsequent air-through processing is preferably more than 0 ° C and 60 ° C or less, and 20 ° C or more and 40 ° C or more. The temperature is more preferably 30 ° C or more and 35 ° C or less. This makes it possible to produce a bulky nonwoven fabric having a good texture.

Furthermore, in the method for manufacturing an air-through nonwoven fabric for absorbent articles according to the present embodiment, as described below, it is preferable to temporarily collect unnecessary portions such as cut pieces generated in the manufacturing process and return to the fiber opening process again (step 504). ).
In this step 504, a step of recovering the widthwise end of the web in the carding machine used in the opening step, and a step of partially collecting the air-through nonwoven fabric and cutting and opening the collected air-through nonwoven portion And one or both of fibering steps. The collected web and the portion of the air-through nonwoven fabric cut and opened are subjected to the opening step. The portion of the air-through nonwoven fabric to be cut and opened includes a cut portion at an end in the width direction, and is not limited to this, and refers to a processed condition-adjusted product or a nonstandard product generated in the nonwoven fabric manufacturing process.

FIG. 2 shows a specific example of the step 504. With respect to the single-layer webs 81 and 82 formed in the carding machine of the carding sections 103 and 104, the ends (not shown) in the width direction are collected by suction (arrows 181 and 182). Further, the air-through nonwoven fabric 10 obtained by performing the air-through processing in the heat treatment unit 107 is partially collected (arrow 183). In this case, since the collected air-through nonwoven fabric cannot be reused as it is, it is cut at the cutting / spreading unit 108 and spread to return to a fibrous state.
The collected web and the portion of the air-through nonwoven fabric cut and opened are returned to the opening section 101, opened again, and used as a material for forming a web (arrow 184). At this time, it is possible to return to either of the fiber opening part 101 and the fiber opening part 102. FIG. 2 shows that the fiber is returned to the fiber opening unit 101. When returning to the fiber opening section 101, a new raw material fiber (fine fiber) is used so that the ratio of the fine fiber in the formed web 81 is maintained at a certain level or more and the content of the thick fiber is kept within several% (for example, within 5%). It is preferable to appropriately adjust the input amount of the (fiber) 71. Thus, the web 81 contains a large amount of fine fibers while forming the fiber mass portion 7, and a soft touch on the surface 10 </ b> A side of the nonwoven fabric 10 can be realized.
Further, the return of the material is not limited to the embodiment shown in FIG. For example, a mode in which the material collected from the carding unit 103 is returned to the opening unit 101 and the material collected from the carding 104 is returned to the opening unit 102 may be adopted. At that time, it is preferable to return the cut-off and opened air-through nonwoven fabric portion to the opening portion 102.

  As described above, according to the manufacturing method of the present embodiment, the patterned nonwoven fabric 10 having excellent bulkiness and soft touch can be suitably manufactured. In particular, the nonwoven fabric having the physical properties indicated by the thicknesses T1, T2 and the difference T3 (= T1−T2) under the above-mentioned 7.64 kPa pressure, and the average friction coefficients Q1, Q2 and the difference Q3 (= Q1−Q2). 10 can be suitably manufactured. In addition, the nonwoven fabric 10 is provided with aesthetics due to the pattern of the fiber lump 7, particularly the pattern of the flat fiber lump 7.

The obtained air-through nonwoven fabric for an absorbent article of the present invention is incorporated as a predetermined constituent member in the absorbent article according to the purpose in the manufacturing process of the absorbent article (incorporation step). The incorporation step is preferably, for example, the following step. That is, the obtained air-through nonwoven fabric for an absorbent article of the present invention is prepared by cutting it into a size or a shape according to the purpose, and is placed at a predetermined position with respect to other constituent members. Next, if necessary, the member is rotated and folded together with other members, and is joined and incorporated into an absorbent article. As described above, the target absorbent article is manufactured through the step of incorporating the air-through nonwoven fabric for the absorbent article of the present invention in the manufacturing step of the absorbent article.
Above all, the air-through nonwoven fabric for absorbent articles of the present invention achieves both bulkiness and soft touch, and has a pattern that can be visually appealed to the user. It is preferably a step of incorporating the outermost layer member (for example, a topsheet or a sidesheet) on the skin side. In particular, it is preferable to incorporate the absorbent article into the absorbent article as a surface sheet that touches the skin and is most noticeable. In that case, it is preferable that the air-through nonwoven fabric for an absorbent article of the present invention has a configuration in which the fiber layer having the fiber lump is the outermost layer of the nonwoven fabric. It is more preferable that the air-through nonwoven fabric for an absorbent article of the present invention is arranged on the outermost layer on the skin side of the absorbent article, and the fiber layer having the fiber mass is arranged toward the skin side of the absorbent article. .

  With respect to the above-described embodiments, the present invention further discloses the following air-through nonwoven fabric for absorbent articles and a method for producing the air-through nonwoven fabric for absorbent articles.

<1>
An air-through nonwoven fabric for an absorbent article, which is an air-through nonwoven fabric in which two or more fiber layers are laminated, wherein the air-through nonwoven fabric contains thermoplastic fibers and has at least one fiber layer having a fiber mass portion.

<2>
The air-through nonwoven fabric for absorbent articles has a fiber diameter of 1 dtex or more and 2.2 dtex or less, preferably 1 dtex or more, more preferably 1.2 dtex or more, preferably 2 dtex or less, more preferably 1.5 dtex or less, Having a thick fiber with a larger fiber diameter than the fine fiber,
The air-through nonwoven fabric for an absorbent article according to <1>, wherein the fiber layer having the fiber mass portion includes the fine fibers.
<3>
The air-through for an absorbent article according to <2>, wherein the content of the fine fibers in the fiber layer having the fiber mass portion is 50% by mass or more, preferably 80% by mass or more, and more preferably 100% by mass. Non-woven fabric.

<4>
The air-through nonwoven fabric for absorbent articles according to any one of <1> to <3>, wherein the air-through nonwoven fabric has at least one fiber layer having no fiber lump portion.
<5>
The air-through nonwoven fabric for absorbent articles has a fiber diameter of more than 2.2 dtex and 7 dtex or less, preferably more than 2.2 dtex, more preferably 4.4 dtex or more, preferably 5.5 dtex or less, more preferably 5 dtex or less. And, having a fine fiber having a smaller fiber diameter than the thick fiber,
The air-through nonwoven fabric for an absorbent article according to <4>, wherein the fiber layer having no fiber mass portion includes the thick fiber.
<6>
The absorbent article according to <5>, wherein the content of the thick fiber in the fiber layer having no fiber mass portion is 50% by mass or more, preferably 80% by mass or more, and more preferably 100% by mass. For air-through non-woven fabric.
<7>
<5> or <6>, wherein the content of the thick fiber in the layer having the fiber mass portion is 50% by mass or less, preferably 30% by mass or less, more preferably 10% by mass or less. Air-through nonwoven fabric for absorbent articles.
<8>
The air-through nonwoven fabric for an absorbent article according to any one of <4> to <7>, wherein the average fiber diameter of the fiber layer having no fiber lump is greater than the fiber layer having the fiber lump.
<9>
The difference between the average fiber diameter of the fiber layer having no fiber lump and the average fiber diameter of the fiber layer having the fiber lump is more than 0 dtex and 5.6 dtex or less, preferably 2.2 dtex or more, more preferably The air-through nonwoven fabric for an absorbent article according to <8>, wherein the air-through nonwoven fabric is at least 3 dtex, preferably at most 4 dtex, more preferably at most 3.5 dtex.
<10>
The air-through nonwoven fabric for an absorbent article according to any one of <4> to <9>, wherein the basis weight of the fiber layer having no fiber lump is greater than the fiber layer having the fiber lump.
<11>
The difference between the basis weight of the fiber layer having no fiber mass portion and the basis weight of the fiber layer having the fiber mass portion is more than 0 g / m ^{2 and} 20 g / m ² or less, preferably 3 g / m ² or more, The air-through nonwoven fabric for absorbent articles according to <10>, wherein the air-through nonwoven fabric is more preferably 5 g / m ² or more, preferably 15 g / m ² or less, and more preferably 10 g / m ² or less.
<12>
The basis weight of the air-through nonwoven fabric for absorbent articles is 15 g / m ² or more and 40 g / m ² or less, preferably 18 g / m ² or more, more preferably 20 / m ² or more, and preferably 30 g / m ² or less. The air-through nonwoven fabric for absorbent articles according to any one of the above items <1> to <11>, more preferably 25 g / m ² or less.

<13>
The thickness of the air-through nonwoven fabric for an absorbent article measured at a pressure of 7.64 kPa at the position where the fiber lump is disposed is T1, and the thickness is measured at the position where the fiber lump is not disposed at the same pressure. When the thickness of the air-through nonwoven fabric for an absorbent article thus obtained is T2, the difference T3 in thickness defined by T3 = T1-T2 is 0.4 mm or less, preferably 0.3 mm or less, more preferably 0.1 mm or less. The air-through nonwoven fabric for an absorbent article according to any one of the above <1> to <12>, which is 2 mm or less, more preferably 0 (zero) mm.
<14>
The average friction coefficient of the air-through nonwoven fabric for the absorbent article at the position where the fiber mass is disposed is 1.6 or more and 2.5 or less, preferably 1.6 or more, preferably 2.4 or less, more preferably. The air-through nonwoven fabric for absorbent articles according to any one of <1> to <13>, which is 2.3 or less.
<15>
The difference between the average friction coefficient of the air-through nonwoven fabric for the absorbent article at the position where the fiber lump is arranged and the average friction coefficient at the position where the fiber lump is not arranged is 0.7 or less, preferably 0 or less. The air-through nonwoven fabric for absorbent articles according to <14>, wherein the air-through nonwoven fabric is at most 0.5, more preferably at most 0.32, still more preferably at most 0.3, particularly preferably 0 (zero).

<16>
<1> to <15, wherein the fiber lump has a flat shape crushed in the thickness direction of the nonwoven fabric in a cross section in the thickness direction of the nonwoven fabric, and the fiber lump surface on the nonwoven fabric surface side has a smooth structure. > The air-through nonwoven fabric for absorbent articles according to any one of <1> to <3>.

<17>
The air-through nonwoven fabric for an absorbent article according to any one of <1> to <16>, wherein the fiber layer having the fiber lump portion is an outermost layer of the air-through nonwoven fabric for the absorbent article.
<18>
An absorbent article having the air-through nonwoven fabric for an absorbent article according to any one of <1> to <17>.
<19>
An absorbent article in which the air-through nonwoven fabric for an absorbent article according to <17> is arranged on the outermost layer on the skin side of the absorbent article, and the fiber layer having the fiber lump is arranged toward the skin side.
<20>
The absorbent article according to <18> or <19>, having the air-through nonwoven fabric for absorbent article as a surface sheet.

<21>
A fiber-spreading step of performing a web-spreading process on the thermoplastic fibers a plurality of times to form a web,
Laminating a plurality of single-layer webs obtained in the fiber opening step to form a laminated web, and performing an air-through process by hot air on the laminated web to obtain an air-through nonwoven fabric,
A method for producing an air-through nonwoven fabric for an absorbent article, comprising: a calendering step of applying one or more of the single-layer web, the laminated web and the air-through nonwoven fabric using a pair of calender rolls.
<22>
In all steps of the manufacturing method of the air-through nonwoven fabric for absorbent articles,
The method for producing an air-through nonwoven fabric for absorbent articles according to <21>, wherein the linear pressure in the calendering step is the highest among the linear pressures applied to the single-layer web, the laminated web, and the air-through nonwoven fabric.
<23>
The method for producing an air-through nonwoven fabric for absorbent articles according to <21> or <22>, wherein the calendering step is a web calendering step performed on one or more selected from the single-layer web and the laminated web. .
<24>
In the web calendering step, a linear pressure applied to the single-layer web or the laminated web is 20 N / cm or more and 700 N / cm or less, preferably 100 N / cm or more, more preferably 180 N / cm or more, and preferably 500 N / cm. The method for producing an air-through nonwoven fabric for an absorbent article according to <23>, wherein the non-woven fabric is at most 250 N / cm or less.
<25>
The method for producing an air-through nonwoven fabric for absorbent articles according to any one of <21> to <24>, wherein the pair of calender rolls used in the calendering step is a combination of a resin roll and a steel roll.
<26>
<25> The resin roll according to <25>, wherein the resin roll has a D hardness of 20 or more and 100 or less, preferably 50 or more, more preferably 80 or more, preferably 95 or less, and more preferably 90 or less. A method for producing an air-through nonwoven fabric for absorbent articles.

<27>
The absorbent article according to any one of <21> to <26>, wherein the air-through processing has a plurality of air-through processings, and a later-stage air-through processing has a higher velocity of hot air than a first air-through processing. Manufacturing method of air-through nonwoven fabric.
<28>
The wind speed of the hot air in the first air-through treatment is 0.2 m / sec or more and 1.2 m / sec or less, preferably 0.25 m / sec or more, more preferably 0.4 m / sec or more, and preferably 0.8 m / sec or more. The method for producing an air-through nonwoven fabric for absorbent articles according to <27>, wherein the air-through nonwoven fabric is not more than 0.5 sec / sec, more preferably not more than 0.5 m / sec.
<29>
The wind velocity of the hot air in the latter air-through treatment is 0.8 m / sec or more and 1.6 m / sec or less, preferably 0.9 m / sec or more, more preferably 1.2 m / sec or more, and preferably 1.4 m / sec or more. The method for producing an air-through nonwoven fabric for absorbent articles according to the item <27> or <28>, wherein the air-through nonwoven fabric is not more than sec, more preferably not more than 1.3 m / sec.
<30>
The difference between the wind speed of the hot air in the first air-through process and the wind speed of the hot air in the subsequent air-through process is more than 0 m / sec and 1.4 m / sec or less, preferably 0.4 m / sec or more, and more preferably 0.1 m / sec or more. The method for producing an air-through nonwoven fabric for an absorbent article according to any one of the above items <27> to <29>, which is at least 8 m / sec, preferably at most 1.2 m / sec, more preferably at most 1 m / sec.
<31>
The absorbent article according to any one of <21> to <30>, wherein the air-through processing has a plurality of air-through processings, and the temperature of hot air is higher in a later-stage air-through processing than in an initial air-through processing. Manufacturing method of air-through nonwoven fabric.
<32>
The temperature of the hot air in the first air-through treatment is 85 ° C. or more and 134 ° C. or less, preferably 90 ° C. or more, more preferably 100 ° C. or more, preferably 115 ° C. or less, and more preferably 105 ° C. or less. The method for producing an air-through nonwoven fabric for absorbent articles according to <1>.
<33>
The temperature of the hot air in the subsequent air-through treatment is not less than the melting point of the component on the fiber surface used and not more than 145 ° C., preferably not less than the melting point of the component on the fiber surface used, preferably not more than 137 ° C., more preferably not more than 134 ° C. The method for producing an air-through nonwoven fabric for an absorbent article according to <31> or <32>, wherein
<34>
The difference between the temperature of the hot air in the first air through process and the temperature of the hot air in the subsequent air through process is more than 0 ° C. and 60 ° C. or less, preferably 20 ° C. or more, more preferably 30 ° C. or more, and preferably 40 ° C. or less. The method for producing an air-through nonwoven fabric for an absorbent article according to any one of the above <31> to <33>, which is preferably at most 35 ° C.

<35>
A step of collecting the width direction end of the web in the carding machine used in the opening step, and a step of partially collecting the air-through nonwoven fabric and cutting and opening the collected air-through nonwoven portion. Have one or both,
The method for producing an air-through nonwoven fabric for absorbent articles according to any one of <21> to <34>, wherein the collected web and the cut and opened portion of the air-through nonwoven fabric are subjected to the opening process.

<36>
The method for producing an air-through nonwoven fabric for absorbent articles according to any one of <21> to <35>, wherein the laminated web has a plurality of types of fibers having different fiber diameters.
<37>
The laminated web has fine fibers having a fiber diameter of 1 dtex or more and 2.2 dtex or less, preferably 1 dtex or more, more preferably 1.2 dtex or more, preferably 2 dtex or less, more preferably 1.5 dtex or less. The method for producing an air-through nonwoven fabric for an absorbent article according to any one of <21> to <36>.

<38>
A method for manufacturing an absorbent article, comprising a step of incorporating the air-through nonwoven fabric for an absorbent article manufactured by the manufacturing method according to any one of <21> to <37> into the absorbent article.
<39>
The method for producing an absorbent article according to <38>, further comprising a step of incorporating the air-through nonwoven fabric for an absorbent article as a surface sheet into the absorbent article.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not construed as being limited thereto. In the table below, “←” means the same as the description on the left.

(Example 1)
Using the manufacturing apparatus shown in FIG. 2, a nonwoven fabric sample of Example 1 was produced as shown below at a processing speed of 10 m / min.
First, as a raw material fiber (fine fiber) 71 forming the fiber layer 1, a core-sheath type thermoplastic fiber having a fiber diameter of 1.4 dtex (core is polyethylene terephthalate resin, sheath is polyethylene resin) was used. Using this raw material fiber 71, the fiber opening processing was performed a plurality of times in the fiber opening part 101 and the carding part 103 to produce a single-layer web 81 having a basis weight of 10 g / m ² .
As the raw material fiber (thick fiber) 72 forming the fiber layer 2, a thermoplastic fiber of a core-sheath type having a fiber diameter of 4.4 dtex (core is polyethylene terephthalate resin, sheath is polyethylene resin) was used. The raw fiber 72 was subjected to multiple opening processing in the opening section 102 and the carding section 104 to produce a single-layer web 82 having a basis weight of 15 g / m ² .
Next, in the laminated web forming unit 105, the laminated web 90 was formed by laminating the single-layer web 82 on the single-layer web 81. In the web calender section 106, the laminated web 90 was subjected to web calendering. In the web calender part 106, the linear pressure was set to 200 N / cm using a calender roll 106A of a steel body on the upper layer side and a resin roll 106B (D hardness: 90 degrees) of the lower layer side.
The laminated web 95 subjected to the web calendering was subjected to the air-through processing in which the air-through processing shown in FIG. The wind speed and temperature of the first air-through process and the second air-through process were as shown in Table 1. Thus, a nonwoven fabric sample of Example 1 was produced.
In the above-described production method, the widthwise end of the formed web and a part of the nonwoven fabric were not recovered and returned to the fiber opening step. Therefore, the fiber diameter of the raw fiber (fine fiber) 71 was the average fiber diameter of the fiber layer 1, and the fiber diameter of the raw fiber (thick fiber) 72 was the average fiber diameter of the fiber layer 2.

(Examples 2 to 7)
The nonwoven fabric samples of Examples 2 to 7 were produced in the same manner as in Example 1 except that the temperature and the wind speed of the first air-through treatment were as shown in Table 1.

(Example 8)
A nonwoven fabric sample of Example 8 was produced in the same manner as in Example 1 except that the nonwoven fabric after air-through processing was subjected to the nonwoven fabric calendering processing shown in Table 1 without performing web calendering.

(Example 9)
Example 1 was repeated in the same manner as in Example 1 except that the fiber diameter of the raw material fibers (fine fibers) forming the fiber layer 1 was 2.0 dtex, and the temperature and wind speed of the first air-through treatment were as shown in Table 1. Nine nonwoven fabric samples were prepared.

(Example 10)
A nonwoven fabric sample of Example 10 was produced in the same manner as in Example 9, except that the fiber diameter of the raw material fiber 72 forming the fiber layer 2 was 2.0 dtex.

(Example 11)
The same procedure as in Example 10 was carried out except that the fiber diameter of the raw fibers (fine fibers) forming the fiber layer 1 and the fiber diameter of the raw fibers 71 forming the fiber layer 2 (lower layer) were 1.4 dtex. Eleven nonwoven fabric samples were prepared.

(Example 12)
A nonwoven fabric sample of Example 12 was produced in the same manner as in Example 11, except that the temperature and the wind speed of the first air-through treatment were as shown in Table 2.

(Example 13)
A nonwoven fabric sample of Example 13 was prepared in the same manner as in Example 12, except that the nonwoven fabric after air-through processing was subjected to the nonwoven fabric calendaring shown in Table 2 without performing web calendering.

(Comparative Example 1)
A nonwoven fabric sample of Comparative Example 1 was prepared in the same manner as in Example 1 except that the calendering was not performed.

(Comparative Example 2)
A nonwoven fabric sample of Comparative Example 2 was produced in the same manner as in Comparative Example 1, except that the fiber diameter of the raw material fiber 71 forming the fiber layer 2 (lower layer) was 1.4 dtex.

(test)
[1] Bulkiness (1) Thickness of nonwoven fabric sample under 0.05 kPa load Measured using a laser sensor (model number ZS-LD80) and a controller (model number ZS-LDC11) manufactured by OMRON Corporation as a laser-type thickness gauge.
When measuring the thickness, a weight (0.05 kpa) was placed between the tip of the laser sensor and the nonwoven fabric sample to be measured, and the thickness in such a pressurized state was measured. The measurement was performed at five or more points, and the average value was obtained. Note that 0.05 kPa is a load assuming the apparent thickness of the nonwoven fabric so as not to crush the thickness as much as possible.
(2) Thickness of nonwoven fabric sample under 7.64 kPa pressure Based on the method described in (Method of measuring thickness of nonwoven fabric under 7.64 kPa pressure), the position of the fiber mass portion of each nonwoven fabric sample was determined. The thickness (T1) and the thickness (T2) at the position where the fiber lump was not arranged were measured. Further, the difference in thickness (T3 = T1-T2) was calculated.
[2] Friction Based on the method described in the above (Method for measuring average friction coefficient), MIU value (Q1) at the position where the fiber lump portion of each nonwoven fabric sample was placed, the position where the fiber lump portion was not placed , And the MIU value (Q2) was measured. Furthermore, the difference Q3 (= Q1-Q2) of the MIU values was calculated.
[3] Pattern For each nonwoven fabric sample, the presence or absence of a fiber lump was visually confirmed.

As shown in Tables 1 and 2, in Examples 1 to 13, compared to Comparative Examples 1 and 2, the thickness T1 at the position where the fiber lump was disposed under the pressure of 7.64 kPa and the fiber lump were not disposed. The difference T3 from the thickness T2 at the position was small, and the bulkiness of the entire nonwoven fabric was excellent. In particular, among the examples, the non-woven fabric subjected to the heat treatment after the web calender was thicker than the non-woven fabric calendered after the non-woven fabric, and had a good texture of the fiber mass portion.
In Examples 1 to 13, the average friction coefficient Q1 at the position where the fiber lump was arranged and the position where the fiber lump was not arranged were compared with Comparative Examples 1 and 2, while the pattern of the fiber lump was confirmed. , The average friction coefficient Q2 and the difference Q3 between the two were small, and soft touch was realized in the entire nonwoven fabric.
As described above, Examples 1 to 13 were excellent in bulkiness and soft touch, were provided with a pattern, and were excellent in aesthetics.

  Although the invention has been described in conjunction with its embodiments and examples, we do not intend to limit our invention in any detail of the description unless otherwise specified, and the spirit and scope of the invention as set forth in the appended claims. It should be interpreted broadly without violating the scope.

Reference Signs List 1 fiber layer 2 fiber layer 7 fiber lump 8 fiber lump layer (layer having fiber lump)
9 Non-fiber lump layer (layer without fiber lump)
Reference Signs List 10 Air-through nonwoven fabric for absorbent article 100 Air-through nonwoven fabric manufacturing apparatus for absorbent article 101, 102 Spreading unit 103, 104 Carding unit 105 Laminated web forming unit 106 Web calender unit 106A, 106B Calendar roll 107 Heat treatment unit (Air-through processing unit) )
117 First air-through processing unit 127 Second air-through processing unit 108 Cutting / spreading units 71, 72 Raw fibers 81, 82 Single-layer web (or web)
90 laminated web 95 laminated web processed by web calendering

Claims (13)

An air-through nonwoven fabric for an absorbent article in which two or more fiber layers are laminated,
An air-through nonwoven fabric for an absorbent article, comprising a thermoplastic fiber and having at least one fiber layer having a fiber mass formed of the thermoplastic fiber.   The air-through nonwoven fabric for an absorbent article according to claim 1, wherein the fiber mass and the fiber are thermally fused. An air-through nonwoven fabric for an absorbent article in which two or more fiber layers are laminated,
Including thermoplastic fiber, and has at least one fiber layer having a fiber mass portion,
The thickness of the air-through nonwoven fabric for an absorbent article measured at a pressure of 7.64 kPa at the position where the fiber lump is disposed is T1, and the thickness is measured at the position where the fiber lump is not disposed at the same pressure. When the thickness of the air-through nonwoven fabric for an absorbent article thus obtained is T2, the difference T3 in thickness defined by T3 = T1−T2 is equal to 0. An air-through nonwoven fabric for absorbent articles having a size of 3 mm or less. An air-through nonwoven fabric for an absorbent article in which two or more fiber layers are laminated,
Including thermoplastic fiber, and has at least one fiber layer having a fiber mass portion,
An absorbent article, wherein the fiber layer having the fiber lump portion is the outermost layer of the air-through nonwoven fabric for the absorbent article, and the air-through nonwoven fabric for the absorbent article is disposed on the outermost layer on the skin side of the absorbent article. For air-through non-woven fabric. Before SL least one layer has a no fiber layer fibrous mass portion,
The basis weight of the fiber layer without the fiber lump is greater than the fiber layer with the fiber lump,
The difference between the basis weight of the fiber layer having no fiber lump and the basis weight of the fiber layer having the fiber lump is more than 0 g / m ^{2 and} 20 g / m ² or less . The air-through nonwoven fabric for absorbent articles according to claim 1 .   The air-through nonwoven fabric for an absorbent article according to any one of claims 1 to 5, wherein an average coefficient of friction at a position where the fiber mass portion is arranged is 1.6 or more and 2.5 or less.   The air-through for an absorbent article according to claim 6, wherein a difference between an average friction coefficient at a position where the fiber mass portion is arranged and an average friction coefficient at a position where the fiber mass portion is not arranged is 0.7 or less. Non-woven fabric. The air-through nonwoven fabric for absorbent articles has a fine fiber whose fiber diameter is 1 dtex or more and 2.2 dtex or less, and a thick fiber whose fiber diameter is larger than the fine fiber.
The fiber layer having the fiber mass portion contains the fine fibers,
The air-through nonwoven fabric for absorbent articles according to any one of claims 1 to 7, wherein the content of the fine fibers in the fiber layer having the fiber lump portion is 50% by mass or more.   An absorbent article comprising the air-through nonwoven fabric for an absorbent article according to any one of claims 1 to 8. A fiber-spreading step of performing a web-spreading process on the thermoplastic fibers a plurality of times to form a web,
Laminating a plurality of single-layer webs obtained in the fiber opening step to form a laminated web, and performing an air-through process by hot air on the laminated web to obtain an air-through nonwoven fabric,
A web calendering step for one or more selected from the single-layer web and the laminated web. A fiber-spreading step of performing a web-spreading process on the thermoplastic fibers a plurality of times to form a web,
Laminating a plurality of single-layer webs obtained in the fiber opening step to form a laminated web, and performing an air-through process by hot air on the laminated web to obtain an air-through nonwoven fabric,
A calendering step of using a pair of calender rolls for one or more selected from the single-layer web, the laminated web and the air-through nonwoven fabric,
A method for producing an air-through nonwoven fabric for absorbent articles, wherein the air-through processing has a plurality of air-through treatments. The method for producing an air-through nonwoven fabric for absorbent articles according to claim 10 or 11, wherein the air-through processing includes a plurality of air-through processings, and the air velocity of a hot air is higher in a later-stage air-through processing than in an initial air-through processing. The air-through nonwoven fabric for an absorbent article according to any one of claims 10 to 12, wherein the air-through processing has a plurality of air-through processings, and the temperature of hot air is higher in a later-stage air-through processing than in an initial air-through processing. Manufacturing method.

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