JP2014025187A - Nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonwoven fabric that has soft touch and superior cushioning property, is superior in liquid permeability while suppressing the liquid diffusion, and improves smoothness on its surface.SOLUTION: A nonwoven fabric 10 with sheet form comprises a first protruded portion 11 protruded on a first surface side Z1 on a planarly viewed side and having an internal space 11K, and a second protruded portion 12 protruded on a second surface side Z2 opposite to the first surface side Z1 and having an internal space 12K. The fabric comprises a wall portion 11W with ring shape formed between an apex 11T of the first protruded portion 11 and an opening 11H of the internal space 11K. The first and second protruded portions 11 and 12 are alternatively and continuously positioned in different cross-sectional directions planarly viewed therefrom. The hydrophilicity of the fiber located on the first surface side Z1 is lower than the hydrophilicity of the fiber located on the second surface side Z2.

Description

  The present invention relates to a nonwoven fabric.

  Absorbent articles such as sanitary napkins, panty liners, disposable diapers, etc., depending on its function, those with a protruding part on one side of the sheet material, those with a protruding part, and many Products with small holes have been developed.

  Patent Document 1 discloses a multilayer nonwoven fabric in which streak-like convex portions and groove portions are alternately arranged in parallel on one side of a sheet material, and the cross-section thereof is a kamaboko (substantially semicircular) shape. The groove part and the convex part are formed by the movement of fibers by spraying gas. Therefore, the groove portion has a high content of laterally oriented fibers and a low fiber density and basis weight, and the side portion of the convex portion has a high content of longitudinally oriented fibers and a high fiber density and basis weight. Thereby, the liquid permeability in the groove portion is increased, and the convex portion has a porous structure to suppress the liquid retention, and the liquid residue hardly occurs. In addition, the contact area between the liquid and the skin is supposed to be small.

  Patent Document 2 discloses a fiber sheet having a concavo-convex structure, in which the top portion of the convex portion is hydrophobic and the other portion is less hydrophobic or hydrophilic than the top portion. This fiber sheet consists of two layers, and the lower layer consists of heat-shrinkable fibers. The convex portion is obtained by forming a concave portion by embossing, and then heat-shrinking the lower layer heat-shrinkable fiber at a non-embossed portion by heat treatment to make the upper layer bulky. Further, a hydrophobic oil agent is applied to the top of the convex portion. Thereby, the liquid quickly moves from the hydrophobic top to the hydrophilic bottom and the absorbency is improved. The liquid does not easily remain on the top, and the dry feeling is maintained without backflow.

  Patent Document 3 discloses a non-woven fabric that includes a heat-extensible conjugate fiber whose length is increased by heating and has a hydrophilic gradient in the thickness direction and the plane direction. As an embodiment of this non-woven fabric, a non-woven fabric in which one side of the non-woven fabric has an uneven shape by embossing and the hydrophilicity of the non-embossed portion is lower than the embossed portion is disclosed. This difference in hydrophilicity is caused by the hot air easily passing through the non-embossed portion having high air permeability during the hot air treatment, and the extensible fibers are elongated and the hydrophilicity is lowered. As a result, the remaining liquid amount, the liquid return amount, and the liquid flow amount are reduced.

JP 2008-25081 A JP 2006-183168 A JP 2010-168715 A

However, in the nonwoven fabric disclosed in Patent Document 1, since the fiber density of the convex portion is larger than that of the groove portion, the liquid accumulated in the groove portion hardly flows to the convex portion side, and there is a problem in improving the liquid passage speed. Further, since the groove portion is streaked along the convex portion, the liquid is likely to diffuse. Furthermore, since the convex portion is not easily crushed by the pressure at the time of wearing, the cushioning property is low.
Moreover, the fiber sheet disclosed in Patent Document 2 has a concavo-convex shape only on one side by embossing, and the convex part is filled with fibers up to the bottom part and has no internal space.
Furthermore, in the nonwoven fabric currently disclosed by patent document 3, it is the uneven | corrugated shape of only one side by embossing, and the convex part is satisfy | filled with the fiber to the bottom part, and does not have internal space.
The present invention relates to a non-woven fabric having a soft touch and excellent cushioning properties, excellent liquid permeability while suppressing liquid diffusion, and improved surface smoothness.

  The present invention has a first projecting portion projecting on the first surface side of the sheet-like nonwoven fabric in plan view and having an internal space, and projecting on the second surface side opposite to the first surface side and having an internal space. A second projecting portion, and a wall portion having an annular structure between a top portion of the first projecting portion and an opening portion of the inner space, and the first and second projecting portions are the nonwoven fabric. A non-woven fabric is provided which is alternately and continuously arranged in different directions crossing each other in plan view, and has a lower hydrophilicity of the fibers on the first surface side than the hydrophilicity of the fibers on the second surface side.

  The nonwoven fabric of the present invention has a soft touch and excellent cushioning properties, has excellent liquid permeability while suppressing liquid diffusion, can reduce soft stool adhesion, and can improve the smoothness of the surface. Has an effect.

It is the fragmentary sectional perspective view which showed typically the principal part which showed preferable one Embodiment of the nonwoven fabric of this invention. It is a longitudinal cross-sectional view of the 1st protrusion part, the 2nd protrusion part, and wall part of the nonwoven fabric of this invention. It is the plane arrangement | positioning figure which showed the example of arrangement | positioning of the 1st, 2nd protrusion part of the nonwoven fabric of this invention. It is explanatory drawing which showed one preferable embodiment of the manufacturing method of the nonwoven fabric of this invention, (1) shows the mode of blowing of a 1st hot air, (2) shows the fiber web by blowing a 1st hot air. The state is shown, and (3) shows the state of blowing the second hot air.

A preferred embodiment of the nonwoven fabric according to the present invention will be described below with reference to FIGS.
The nonwoven fabric 10 of the present invention is preferably applied to a surface sheet of an absorbent article such as a sanitary napkin or a disposable diaper. The first surface side Z1 is used with the skin surface side of the wearer, and the second surface side Z2 is used. Is preferably disposed on the absorbent body (not shown) side inside the absorbent article. Hereinafter, although it demonstrates considering the embodiment which uses the 1st surface side Z1 of the nonwoven fabric 10 shown in drawing toward a wearer's skin surface, this invention is limited to this and is not interpreted.

  As shown in FIG. 1, the nonwoven fabric 10 projects from the first surface side Z1 on the side of the sheet-like nonwoven fabric in plan view and has an internal space 11K, and the first surface side Z1 is on the opposite side of the first surface side Z1. It has the 2nd protrusion part 12 which protrudes in the 2nd surface side Z2 and has internal space 12K. These 1st, 2nd protrusion parts 11 and 12 are distribute | arranged alternately by each of the different direction which crosses planar view over the whole surface of the nonwoven fabric 10, for example. The different direction is, as a specific example, an X direction which is one direction of the different directions and a Y direction which is one direction of the different directions unlike the X direction. Here, the convex portion viewed from the first surface side Z <b> 1 is the first projecting portion 11, and the concave portion is the second projecting portion 12. Further, the convex portion viewed from the second surface side Z <b> 2 is the second projecting portion 12, and the concave portion is the first projecting portion 11. And the internal space 12K which the 2nd protrusion part 12 has is the space which the said recessed part which looked at the 2nd protrusion part 12 from the 1st surface side Z1 makes, and the 1st surface side Z1 extends from the top part of the 2nd protrusion part 12. It has the opening part 12H open | released toward. The internal space 11K of the first protrusion 11 is a space formed by the recess when the first protrusion 11 is viewed from the second surface side Z2, and from the top of the first protrusion 11 toward the second surface side Z2. It has the opening part 11H opened. A part of the first protrusion 11 and the second protrusion 12 is shared. The intersection angle between the x-axis and the y-axis is preferably 30 ° or more and 90 ° or less, and is 90 ° in this embodiment. The first surface side Z1 is the upper side in the z-axis direction, and the second surface side Z2 is the lower side in the z-axis direction.

  In this embodiment, the 1st, 2nd protrusion parts 11 and 12 are made into the truncated cone shape or hemisphere which rounded the top parts 11T and 12T. More specifically, the protruding shape of the first protruding portion 11 is somewhat hemispherical, while the protruding shape of the second protruding portion 12 is a cone or truncated cone shape with a round top. In addition, in this embodiment, the 1st, 2nd protrusion parts 11 and 12 are not limited to the said shape, What kind of protrusion form may be sufficient, for example, various cone shape (In this specification, cone shape is It is practical to include a cone, a truncated cone, a pyramid, a truncated pyramid, an oblique cone, etc.). In this embodiment, the 1st, 2nd protrusion parts 11 and 12 hold | maintain the frustoconical shape or hemispherical internal space 11K and 12K with the roundness in the top part similar to the external shape.

A wall 11W is provided between the top of the first protrusion 11 (hereinafter also referred to as the first protrusion 11) 11T and the opening 11H. The wall portion 11 </ b> W forms an annular structure in the first projecting portion 11. Moreover, it has the wall part 12W between the top part (henceforth the 2nd protrusion part top part) 12T of the 2nd protrusion part 12, and the opening part 12H. The wall portion 12 </ b> W forms an annular structure at the second projecting portion 12. The wall portion 12W is shared with the wall portion 11W.
The “annular” herein is not particularly limited as long as it has a series of endless shapes in plan view, and may be any shape such as a circle, an ellipse, a rectangle, or a polygon in plan view. In order to maintain the continuous state of the sheet suitably, a circle or an ellipse is preferable. Furthermore, speaking of “annular” as a three-dimensional shape, any ring structure such as a cylinder, an oblique cylinder, an elliptical column, a truncated cone, a truncated cone, a truncated elliptical cone, a truncated quadrangular pyramid, and a truncated oblique pyramid In order to realize a continuous sheet state, a cylinder, an elliptical column, a truncated cone, and a truncated elliptical cone are preferable.

  In addition, the 1st protrusion part top part 11T, the wall part 11W, and the 2nd protrusion part top part 12T are basically the upper part P1 which divided the nonwoven fabric thickness into three equal parts, the first protrusion part top part 11T, and the intermediate part P3 is the wall part 11W. (12W), let the lower part P2 be the 2nd protrusion top part 12T (refer FIG. 2). In addition, when the thickness of the nonwoven fabric as viewed from the side is thin and the thickness of the nonwoven fabric is large, or when the kurtosis or the curvature of each apex is different, the apex of the second protrusion adjacent to the first protrusion 11Tp in the cross section It is a curved surface obtained by rotating an orthogonal line on the first protruding portion vertex 11Tp side with respect to the straight line at each position obtained by dividing the straight line up to 12 Tp into three equal parts around a line parallel to the z axis passing through the first protruding portion vertex 11Tp. The upper part of the divided nonwoven fabric is divided by a curved surface obtained by rotating an orthogonal line on the first protruding portion apex 11T and the second protruding portion apex 12Tp around a line parallel to the z axis passing through the second protruding apex 12Tp. The lower part of the non-woven fabric may be the second projecting part top part 12T, and the space between the first projecting part top part 11T and the second projecting part top part 12T may be the wall part 11W (wall part 12W) (see FIG. 2). Or it is good also considering the part which became linear in the cross section as a wall part, and each area | region which curves and rounds from there as each protrusion part. Furthermore, the 1st protrusion part 11 contains the 1st protrusion part top part 11T and the wall part 11W, the 2nd protrusion part 12 contains the 2nd protrusion part top part 12T and the wall part 12W, and the wall parts 11W and 12W are shared.

  The walls 11W and 12W can also be defined as side walls that separate the internal space 11K and the internal space 12K. Specifically, the nonwoven fabric portions sandwiched between the opening 12H of the internal space 12K and the opening 11H of the internal space 11K are the wall portions 11W and 12W. In this case, the opening 12H is an annular shape formed by connecting the position closest to the second protrusion 12 of the ridge formed so as to connect the tops 11T of the first protrusion 11 surrounding the inner space 12K. Part. The opening 11H is an annular portion formed by connecting the positions of the ridges that are formed so as to connect the tops 12T of the second protrusions that surround the periphery of the internal space 11K to the first protrusion 11 side.

The nonwoven fabric 10 having the first and second projecting portions 11 and 12 arranged as described above does not have a bent portion, and has a double-sided concavo-convex structure composed entirely of a curved surface.
Thus, it is preferable that the said nonwoven fabric 10 has a structure continuous in the surface direction. This “continuous” means that there are no intermittent portions or small holes. However, fine holes such as gaps between fibers are not included in the small holes. The small hole is defined as, for example, a hole having a diameter equivalent to a circle of 1 mm or more.

  The fiber material that can be used for the nonwoven fabric 10 of the present invention is not particularly limited. For example, the following fibers are specifically mentioned. Polyolefin fibers such as polyethylene (PE) fibers and polypropylene (PP) fibers; fibers using a thermoplastic resin such as polyethylene terephthalate (PET) and polyamide alone; composite fibers having a structure such as a core-sheath type and a side-by-side type, such as A core-sheath structure fiber in which the sheath component is polyethylene or low-melting-point polypropylene is preferable, and representative examples of the core / sheath structure fiber include PET (core) and PE (sheath), PP (core) and PE (core). Sheath), fibers of core-sheath structure such as PP (core) and low melting point PP (sheath). More specifically, the constituent fibers preferably include polyolefin fibers such as polyethylene fibers and polypropylene fibers, polyethylene composite fibers, and polypropylene composite fibers. Here, the composite composition of the polyethylene composite fiber is polyethylene terephthalate and polyethylene, and the composite composition of the polypropylene composite fiber is preferably polyethylene terephthalate and low-melting polypropylene, and more specifically, PET (core). And PE (sheath), PET (core), and low melting point PP (sheath). These fibers may be used alone to form a nonwoven fabric, but may be used in combination of two or more.

  In the nonwoven fabric 10, the hydrophilicity of the fiber on the first surface side Z1 is lower than the hydrophilicity of the fiber on the second surface side Z2. Here, the difference in hydrophilicity is not only the difference between the surface of the first surface side Z1 and the surface of the second surface side Z2, but also the first surface side to the second surface side within the layer thickness of the sheet. On the other hand, it is preferable that the hydrophilicity is relatively low. Furthermore, it is preferable that there is a hydrophilic gradient that increases from the first surface side Z1 toward the second surface side Z2. The term “gradient” means not only a continuously increasing hydrophilic gradient, but also includes a state in which the hydrophilicity is increased from the first surface side Z1 to the second surface side Z2 even intermittently or in multiple stages. .

The degree of hydrophilicity is indicated by the contact angle of water with respect to the fiber, and the smaller the contact angle, the higher the hydrophilicity. The difference in the contact angle of water with respect to the fibers on the first surface side Z1 and the second surface side Z2 is preferably 7 degrees or more, and more preferably 8 degrees or more. The upper limit is preferably 10 degrees or less, and more preferably 9 degrees or less. The mobility of a liquid improves by setting it as the said minimum or more. The difference in contact angle refers to the difference between the contact angle of the fiber on the first surface side Z1 surface and the contact angle of the fiber on the second surface side Z2 surface.
In addition, the contact angle of water with the fibers near the first surface is preferably 74 ° or more, more preferably 76 ° or more, from the viewpoint of reducing liquid residue and allowing liquid to permeate quickly. The upper limit is preferably 80 degrees or less. On the other hand, the contact angle of water with respect to the fibers in the vicinity of the second surface is preferably 64 degrees or more from the viewpoint of suitable drawing of the liquid, and the upper limit is preferably 73 degrees or less, 71 More preferably, it is less than or equal to the degree.

<Measurement method of contact angle>
The contact angle is measured by the following method.
As a measuring device, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. Distilled water is used for contact angle measurement. The amount of liquid ejected from an ink jet system water droplet ejection section (manufactured by Cluster Technology Co., Ltd., pulse injector CTC-25 having a pore diameter of 25 μm) is set to 20 picoliter, and water droplets are dripped just above the fibers. The state of dripping is recorded on a high-speed recording device connected to a horizontally installed camera. The recording device is preferably a personal computer incorporating a high-speed capture device from the viewpoint of image analysis or image analysis later. In this measurement, an image is recorded every 17 msec. In the recorded video, the first image of water droplets on the fiber is attached to the attached software FAMAS (software version is 2.6.2, analysis method is droplet method, analysis method is θ / 2 method, image processing algorithm Is non-reflective, the image processing image mode is frame, the threshold level is 200, and the curvature is not corrected). Image analysis is performed to calculate the angle between the surface of the water droplet that touches the air and the fiber, and the contact angle And
In addition, the sample for measurement (fiber obtained by taking out from a nonwoven fabric) cut | disconnects the 1st surface side fiber and the 2nd surface part side fiber from the surface layer by fiber length 1mm, and mounts this fiber on the sample stand of a contact angle meter. The contact angle is measured at two different positions for each of the fibers. In each of the above-mentioned parts, N = 5 contact angles are measured to one decimal place, and a total of 10 measured values (rounded to the second decimal place) is calculated as the contact angle at each part. Define. The measurement is performed in an environment of room temperature 20 ° C. and humidity 60%, and distilled water and a measurement sample to be used are used after storage for 1 day or more in the environment.

It is preferable that the difference in hydrophilicity between the first surface side Z1 and the second surface side Z2 occurs in any of the first projecting portion 11, the second projecting portion 12, and the wall portion 11W (12W). It is preferable that the hydrophilic difference is generated at least in the first protrusion 11. Thereby, when there is contact with the liquid on the first surface side, even if the liquid has a high viscosity, the liquid hardly stays in the fibers on the first surface side Z1, and increases to the second surface side Z2. Due to the hydrophilicity of the fiber, the liquid is quickly drawn to the second surface side (see arrows a _{1 to} a _{4 in} FIG. 2).

The difference in hydrophilicity between the first surface side and the second surface side has the following excellent effects in combination with the above-described double-sided uneven structure.
Specifically, for example, when the nonwoven fabric 10 is used as a surface sheet of an absorbent article and the first surface side Z1 thereof is arranged toward the skin surface side, the first protrusion 11 that is closest to the skin within the nonwoven fabric 10 and makes point contact. At the top portion 11T, the excretory fluid is quickly drawn into the internal space 11K on the second surface side and delivered to the absorber (see arrows a ₁ and a _{2 in} FIG. 2). This reduces liquid residue and reduces the burden on the skin.
Moreover, since the whole nonwoven fabric is a continuous uneven | corrugated structure, a liquid transfers to the 2nd protrusion part 12 quickly from the top part 11T of each 1st protrusion part 11 through the cyclic | annular structure wall part 11W (12W), and keeps away from skin. (See arrow b _{1 in} FIG. 2). The transferred liquid is captured in the internal space 12K without diffusing. At this time, also in the 2nd protrusion part 12 containing a wall part, a liquid is rapidly drawn in from the 1st surface side Z1 to the 2nd surface side Z2 by the difference in hydrophilicity, and is handed over to the internal space 11K thru | or an absorber. (See arrows a ₃ and a _{4 in} FIG. 2). This further improves the absorption rate of the liquid and reduces the burden on the skin.
Furthermore, since the hydrophilicity of the first surface side Z1 is lower than that of the second surface side Z2, the liquid once drawn into the internal space 11K is difficult to return, and does not give the wet touch to the skin that is in contact with the first protrusion. Similarly, the liquid does not easily return to the first surface side Z1 in the second projecting portion 12 that makes point contact with the absorber or the intermediate sheet on the second surface side Z2, and the contact between the skin and the liquid is suppressed. it can.
As described above, the nonwoven fabric of the present invention suppresses liquid diffusion and draws in liquid quickly due to the interaction between the unique concavo-convex structure on both sides and hydrophilicity, and effectively suppresses liquid residue and liquid return. The smoothness of the surface can be improved.

The nonwoven fabric 10 demonstrated by the said embodiment has the following effects further.
The nonwoven fabric 10 (see FIG. 1) has excellent cushioning properties.
Since the nonwoven fabric 10 of this embodiment has the part which protruded not only on the single side | surface of a front and back but on both surfaces, the cushioning characteristic peculiar to the structure is expressed. For example, streak-like projections or single-sided projections will inevitably exhibit elasticity as lines or surfaces. However, according to this embodiment, the two-dimensional movement is well followed and supported by points on both sides. Has a three-dimensional cushioning. Further, by having the fiber orientation described later in the direction in which the wall portion 11W (12W) stands up, a firm stiffness is born in the wall portion 11W (12W), and the fiber is not crushed in the thickness direction. Has moderate cushioning properties. Furthermore, due to the fiber orientation in the wall portion 11W (12W), even if the nonwoven fabric 10 is crushed by receiving a pressing force, the shape restoring force is large, and the initial cushioning force is maintained even if the packing state and wearing are continued. Easy to be. That is, the first and second projecting portions 11 and 12 are not easily crushed and can be easily recovered even if deformation occurs.
Since the space for temporarily holding the liquid can be secured by the action due to the above-mentioned good cushioning properties, the absorption speed can be maintained fast, and the pressure applied to the absorber is appropriately dispersed, so the amount of liquid returned from the absorber Is reduced. Moreover, since the shape restoring force is large, the stability of the absorption performance is also ensured.

The nonwoven fabric 10 (see FIG. 1) is excellent in touch.
The nonwoven fabric 10 of this embodiment has the 1st, 2nd protrusion parts 11 and 12 in a double-sided direction, and the top part 11T is rounded. Therefore, the surface on the 1st protrusion part 11 side is made into the skin surface side, and the favorable touch which a surface sheet contacts softly with respect to skin is implement | achieved. In addition, the point of contact with the pressure at the time of wearing increases and decreases in a planar shape, and the shape deformation of the entire topsheet against pressure can be suppressed while improving the touch, and shape restoration from pressure deformation can also be achieved Easy to do. There also exists an effect | action resulting from said favorable cushioning property, and a unique favorable touch is obtained combined with the dynamic effect | action by double-sided point contact. Moreover, the point contact mentioned above has an effect also when excretion etc. are received, and the smooth touch is implement | achieved. Complementing this smooth touch (absorbing effect), it has a fiber orientation described later in the direction in which the wall portion 11W (12W) stands up, so that it is oriented in the thickness direction of the wall portion 11W (12W). The fibers flow smoothly through the fibers and quickly move from the second protrusion 12 to the absorbent body disposed on the lower surface of the nonwoven fabric 10, and the difference in hydrophilicity between the first surface side and the second surface side. As a result, there is little liquid return and a smooth touch is realized. Further, the nonwoven fabric 10 itself is excellent in air permeability by maintaining the above-described structure, and helps prevent fogging by the effect of point contact.

The nonwoven fabric 10 (see FIG. 1) is excellent in excretion capturing ability.
In the nonwoven fabric 10 of this embodiment, since it has internal space 11K and 12K inside each of the 1st, 2nd protrusion parts 11 and 12 which protrude on both surfaces, it is various according to the physical property of excretion liquid and excrement. These can be captured and dealt with in various forms. For example, when the first surface side Z1 of the nonwoven fabric 10 is described as the skin surface side, if it is excrement having high viscosity and low permeability, the excrement is temporarily stored in the internal space 12K without passing through the surface sheet of the nonwoven fabric 10. The water and a part thereof are absorbed by the absorber (not shown) through the second protrusion 12. On the other hand, if the excretory liquid has a low viscosity and is easily permeable, the liquid is mainly trapped in the internal space 11K after passing through the first protrusion 11. In any of these cases, the portion that first hits the skin surface is the first protruding portion top portion 11T, and the captured excretory fluid or excrement is made difficult to come into contact with the skin. As a result, after the excretion of urine, feces, menstrual blood, and spillage, a very good and smooth feeling can be sustained widely.

(Fiber density (first protrusion <second protrusion))
In addition to the above, regarding the fiber density of the nonwoven fabric 10, the fiber density (r ₁ ) of the first protrusions 11 is preferably smaller than the fiber density (r ₂ ) of the second protrusions 12.
Thereby, when excrement is supplied from the 1st surface side Z1 of a nonwoven fabric, fluid penetration resistance is reduced in the 1st projection part 11, and the excrement (not shown) is rapidly led to internal space 11K. At the same time, the liquid moves along the wall portion to the second projecting portion 12 by the capillary force due to the difference in fiber density. This, combined with the above-described effect due to the difference in hydrophilicity, quickly pulls the liquid away from the skin and quickly delivers it to the absorber (not shown). As a result, the excrement becomes difficult to adhere to the skin, and the occurrence of redness, rash, pressure ulcer, etc. of the wearer can be prevented.
Furthermore, in the 1st protrusion part 11, it does not give the feeling which is crushed moderately with respect to a press, and can achieve favorable skin contact. On the other hand, the 2nd protrusion part 12 is hard to be crushed, is excellent in preserving formation after excrement is collected, and is excellent in a good cushioning property and prevention of diffusion of the collected product without collapsing.

The fiber density here is a fiber density near the center of the thickness of each protrusion, and is evaluated by measuring the number of fibers per 1 mm ² . For example, the fiber density of the first protrusion 11 is preferably 30 fibers / mm ² or more, more preferably 50 fibers / mm ² or more, and preferably 130 fibers / mm ² or less. 120 / mm ² or less is more preferable. On the other hand, the fiber density of the second protrusion 12 is preferably 250 fibers / mm ² or more, more preferably 270 fibers / mm ² or more, and preferably 500 fibers / mm ² or less. More preferably, it is 480 pieces / mm ² or less. The difference between the fiber density of the first protrusion 11 and the fiber density of the second protrusion 12 is preferably 150 / mm ² or more, and more preferably 300 / mm ² or more. This difference is preferably as large as possible, but the upper limit is about 700 / mm ² .

<Measurement method of fiber density>
The fiber density can be measured, for example, by the following method.
The cut surface of the nonwoven fabric is magnified using a scanning electron microscope (adjusted to a magnification capable of measuring 30 to 60 fiber cross sections (150 to 500 times), the number of fiber cross sections is measured, and the cut surface per fixed area is measured. The number of cross-sections of the fibers cut by the above is counted, and the center of observation is near the center of the layer thickness TL1 of the top portion 11T for the first projecting portion 11, and in the sheet thickness direction for the wall portion 11W (12W). In the vicinity of the center of the layer thickness TL3 near the center, the second protrusion is in the vicinity of the center of the layer thickness TL2 of the top portion 12T, and then converted into the number of fiber cross-sections per 1 mm ² , which is the fiber density (main / mm ²⁾ to. the measurement was conducted three places, the average of the fiber density of the sample. the scanning electron microscope, Mochiiruko a JEOL Co., Ltd. of JCM-5100 (trade name) Can.

(Fiber density (first surface side <second surface side))
Also, the fiber density of the first surface side fiber density of z1 _{(r 11a)} and the second surface side z2 of the first projecting portion 11 _{(r 11b),} but is preferably in the relationship of _r 11a _{<r 11b.} Thereby, the softness | flexibility and the shape maintenance property in the part are compatible. These effects are usually difficult to achieve in this type of nonwoven fabric. However, by providing the above-mentioned specific fiber density, a structure deformation portion and a structure maintenance portion with respect to external pressure are formed at that portion. Thus, the above-described action can be obtained. If it says, since the fiber of the 2nd surface side Z2 is "dense" in the top part 11T of a 1st protrusion part, a relatively hard part will become on an arch and the function of a pier is fulfilled, and the 1st Since the surface side Z1 is soft and does not become rigid as a whole and maintains sufficient flexibility, it feels soft when touched. Furthermore, the above-described fiber density structure is different in the behavior with respect to the pressure on the rough first surface side Z1 and the dense second surface side Z2, and the fibers are densely stacked along the shape of the first protrusion. The second surface side Z2 that is considered to have a cushioning property due to the structural deformation of the entire first protrusion contributes to a quick restoration of the structure.
In addition, since the fiber density on the second surface side Z2 is higher than the fiber density on the first surface side Z1 at the top portion 11 of the first protrusion, the body fluid is quickly brought into contact with the second surface due to the difference in hydrophilicity described above. The skin that moves to the side Z2 and is in contact with the first surface side Z1 is kept dry.

(Fiber orientation of the wall)
Further, the fibers constituting the wall 11W of the first protrusion 11 are oriented in the direction connecting the first protrusion top 11T and the edge of the opening 11H at any location over the entire circumference of the wall 11W. It is preferable to have properties. In other words, the fibers constituting the wall portion 11W are oriented so as to converge toward the first protruding portion top portion 11, and have fiber orientation in the standing direction. Further, the fibers constituting the wall portion 12W of the second protruding portion 12 are oriented in the direction connecting the second protruding portion top portion 12T and the edge of the opening portion 12H at any location over the entire circumference of the wall portion 12W. It is preferable to have properties. The fiber orientation of the wall portion 12W is similar to the fiber orientation of the wall portion 11W in the common portion with the above-described wall portion 11W. Thereby, both-sides uneven | corrugated shape is easy to be maintained, and the more excellent cushioning property is obtained.
In the conventional general air-through nonwoven fabric, when the nonwoven fabric is usually produced, the fibers are oriented in the MD direction and are fused as they are. Therefore, the fibers of the wall portion in the MD cross section are oriented in the standing direction. In the cross section in the CD direction, since the fibers are oriented in a direction perpendicular to the standing direction, such fiber orientation is not present. MD is also referred to as a machine direction, and is a fiber web feeding direction during the production of a nonwoven fabric, and is an abbreviation for “Machine Direction”. The CD is a direction orthogonal to the MD and is an abbreviation of “Cross Direction”.

The fiber orientation is a concept consisting of an orientation angle and orientation strength of fibers. The fiber orientation angle is a concept that indicates in which direction a plurality of fibers having various directions are oriented as a whole, and the shape of the fiber aggregate is quantified. The orientation strength of the fiber is a concept indicating the amount of fibers exhibiting an orientation angle. The orientation strength is less than 1.05 and is hardly oriented, and it can be said that the orientation strength is 1.05 or more. However, in this embodiment, the fiber orientation changes depending on the part. That is, the orientation strength is changed during the transition from a part having a certain orientation angle to a part having a different orientation angle (while the fiber is changing from a state in which the orientation strength is strong in one direction to a part having a strong strength in a different orientation). It has various states such as a weak state and a high state due to reorientation. Therefore, it is preferable that the orientation angle of the fiber is changed between the part showing a strong orientation angle and the part showing a strong orientation angle in another direction even if the orientation strength of the fiber is weak, and the orientation strength is high. Is more preferable.
An example of the orientation angle and orientation strength is shown in this embodiment. The orientation angle is preferably 50 ° or more and 130 ° or less, more preferably 60 ° or more and 120 with respect to the curved surface structure of the wall portion 11W of the first protrusion 11. The orientation strength is preferably 1.05 or more, and more preferably 1.10 or more. Since the orientation direction of the fibers of the wall portion 11W is the direction toward the center of each apex portion, cushioning properties are expressed. Moreover, when the nonwoven fabric 10 is used as a surface sheet of an absorbent article, the nonwoven fabric 10 has sufficient compression resistance even under high pressure due to the fiber orientation of the wall portion 11W, and the first protrusion 11 of the nonwoven fabric 10 Prevent crushing. As a result, a sufficient capture space can be ensured, and the effect of reducing the skin contact area, high air permeability, a large amount of liquid, solid content, highly viscous liquid, etc. can be sufficiently captured and the effect of suppressing leakage can be sufficiently exhibited.
In the present invention, unless otherwise specified, the direction along the sheet thickness direction is an orientation angle of 90 °, and in the state shown in FIG. 1, the Z-axis (Z1-Z2) direction corresponds to this.

<Measurement method of fiber orientation (orientation angle, orientation strength)>
Fiber orientation (orientation angle and orientation strength) can be measured by the following method.
First, using a scanning electron microscope JCM-5100 (trade name) manufactured by JEOL Ltd., the sample is allowed to stand so that the z-axis direction in FIG. An image photographed from the vertical direction (adjusted to a magnification capable of measuring 10 or more fibers to be measured; 70 to 300 times) is printed, and the fibers are traced on a transparent PET sheet. The said image is taken in in a personal computer and the said image is binarized using the NexusNewQube [brand name] (stand-alone version) image processing software made from Nexus Corporation. Next, the binarized image was subjected to Fourier transform using Fiber Orientation Analysis 8.13 Single software (trade name), which is a fiber orientation analysis program, to obtain a power spectrum, and from an elliptical distribution map, an orientation angle was obtained. And get the orientation strength.
The orientation angle indicates the angle at which the fibers are most oriented, and the orientation strength indicates the strength at the orientation angle. In the measurement of the wall and the first protrusion, the value of the orientation angle closer to 90 ° indicates that the fiber is oriented in the direction toward the top 12T of the second protrusion 12, and is 60 to 120 °. If there is, it is determined that the fibers are oriented toward the top 12T of the second protrusion 12. Moreover, it represents that the direction of a fiber has gathered, so that the value of orientation strength is large. The case where the orientation strength is 1.05 or more is assumed to be oriented. The measurement is performed at three places, and the average is taken as the orientation angle and orientation strength of the sample.

Next, the dimension specification in the nonwoven fabric 10 of this embodiment is demonstrated below.
Regarding the thickness of the sheet, the total thickness when viewed from the side of the nonwoven fabric 10 is the sheet thickness TS, and the local thickness of the sheet curved in the unevenness is the layer thickness TL (see FIG. 1). The sheet thickness TS may be adjusted as appropriate depending on the application, but when used as a surface sheet for diapers, sanitary products, etc., 1 mm to 7 mm is preferable, and 1.5 mm to 5 mm is more preferable. By setting it as the range, the body fluid absorption speed at the time of use is high, the liquid return from an absorber is suppressed, and also moderate cushioning property is realizable. The layer thickness TL may be different in each part in the sheet, and may be appropriately adjusted depending on the application. When used as a top sheet for diapers, sanitary products, etc., the layer thickness TL1 of the first protrusion top 11T is preferably 0.1 mm to 3 mm, more preferably 0.4 mm to 2 mm. The preferable range of the layer thickness is the same for the layer thickness TL2 of the second protrusion top 12T and the layer thickness TL3 of the wall 11W (12W). The relationship between the layer thicknesses TL1, TL2, and TL3 is preferably TL1>TL3> TL2. Thereby, in the 1st protrusion part 11, especially on the skin surface side, fiber density is low and can implement | achieve favorable skin contact. On the other hand, the second protrusion 12 has a high fiber density, is not easily crushed, and can be made of a nonwoven fabric excellent in cushioning properties and liquid absorption speed without being deformed.
What is necessary is just to adjust suitably the space | interval of the said 1st protrusion part 11 and the 2nd protrusion part 12 according to a use, and when using as surface sheets, such as a diaper and sanitary goods, 1 mm-15 mm are preferable, and 3 mm-10 mm are more preferable. The basis weight of the nonwoven fabric 10 is not particularly limited, but is preferably 15 to 50 g / ^{m 2} the average value of the entire sheet, 20 to 40 g / ^{m 2} is more preferable.

Next, a preferred planar arrangement example of the first and second projecting portions 11 and 12 will be described with reference to FIG.
As shown in FIG. 3, the example of arrangement | positioning is the 1st surface part Z1 which protruded in the 1st surface side Z1 (front side toward FIG. 3) of the side which planarly viewed the sheet-like nonwoven fabric, and the 1st surface side Z1. The first direction X and the second direction as different directions in which the second protruding portion 12 protruding to the second surface side Z2 (the back side as viewed in FIG. 3) opposite to the plane intersects the entire surface of the nonwoven fabric 10 in plan view. The two directions Y are arranged alternately and continuously. Accordingly, when viewed in one direction, the first projecting portions 11 and the second projecting portions 12 project alternately in opposite directions with respect to the sheet surface. The crossing angle between the first direction X and the second direction Y is preferably 30 ° or more and 90 ° (orthogonal) or less, for example, 90 °. The same number of second projecting portions 12 as the first projecting portions 11 projecting on the first surface side Z1 are arranged so as to project on the second surface side Z2. And the 1st ridge part 16 which connects the 1st protrusion part 11 adjacent to each is formed. On the other hand, although not shown, a second ridge 17 that connects the second protrusions 12 adjacent to each other is formed when viewed from the second surface side Z2.

  The internal spaces 11K and 12K are separated from each other by the wall portions 11W and 12W with the first ridge portion 16 and the second ridge portion 17 as a boundary, and are configured as spaces that are not substantially continuous. This “ridge portion” refers to a boundary line between two surfaces having an inclination and a convex section, and in this case, the first ridge portion 16 is an intersecting portion of the surface of the internal space 12K of the adjacent second protrusion 12. (Boundary line). In other words, along a ridge line that passes between the second protrusions 12 so as to surround the second protrusions 12 from the adjacent first protrusions 11 via the second protrusions 12 to another first protrusion 11B. Refers to the part. The “ridge line” is a line obtained by continuously connecting the highest positions in the vertical longitudinal section viewed continuously with respect to the line connecting the top portions 11T of the nearest first projecting portion 11. Say.

  In the nonwoven fabric 10 of the above-described arrangement example, the first protrusions 11 are connected via the first ridges 16, and the first protrusions 11 are parallel to the first ridges 16 while the first protrusions 11 are connected. It is connected through. Further, the second protrusions 12 are connected in parallel between the series of the first protrusions 11 and the series of other first protrusions 11. Since it is such an arrangement | positioning form, it has a capture | acquisition space (internal space 12K of a 2nd protrusion part) between the 1st protrusion parts 11 in a row. In addition, the capture space becomes a liquid transfer path, and the series of the first protrusions 11 prevents the liquid from leaking sideways. Note that the second protrusions 12 are also connected via the second ridges 17 on the second surface side Z2, and an internal space 11K is provided between the connections.

  In the above arrangement example, when the crossing angle between the first direction X and the second direction Y is 60 °, the first protrusions 11 and the second protrusions 12 are adjacent to each other. However, as long as a continuous sheet state is formed as a whole, the arrangement of such a form is also different in the first and second directions X and Y as the different directions intersecting in plan view. Since the second protrusions 11 and 12 are alternately and continuously arranged, it is included in the meaning that the first protrusions 11 and the second protrusions 12 are arranged “alternately”.

  As described above, the first protrusion 11 and the second protrusion 12 arranged in the first direction (X direction) and the second direction (Y direction) in plan view are in a state where the whole is continuous with a curved surface, The nonwoven fabric 10 is comprised. In addition, the arrangement | sequence form of the said 1st protrusion part 11 and the 2nd protrusion part 12 is not limited above, What is necessary is just a form which can be arrange | positioned by the arrangement | sequence which can be continued. For example, the arrangement may be such that six second projecting portions 12 are arranged at the apexes of the hexagon with the first projecting portion 11 as the center, and the pattern extends in the plane. In addition, four second protrusions 12 are arranged at the apexes of the square with the first protrusion 11 as the center, and further, the second protrusions 12 are arranged at the centers between the apexes, for a total of eight second protrusions. 12 may be arranged, and the pattern may extend in the plane.

Next, a preferred embodiment of the method for producing the nonwoven fabric 10 will be described below with reference to FIG.
What is necessary is just to employ | adopt a general manufacturing method suitably for the manufacturing method of the above-mentioned nonwoven fabric 10. FIG.
As an example of the support of the manufacturing apparatus, the support 110 having the configuration shown in FIG. The support 110 has a large number of protrusions 111 corresponding to positions where the second protrusions 12 are shaped, and holes 112 are arranged corresponding to positions where the first protrusions 11 are shaped. Yes. That is, the support 110 has an uneven shape, and the protrusions 111 and the holes 112 are alternately arranged in different directions. For example, the protrusions 111 and the holes 112 are alternately arranged in the X direction and the Y direction, respectively. It is arranged.
When a web (also referred to as a fiber web) 50 is arranged on the support 110 and the first hot air W1 is blown toward the web 50, as shown in FIG. The first protrusion 11 is shaped correspondingly, and the second protrusion 12 is shaped corresponding to the position of the protrusion 111. Accordingly, the first projecting portion 11 projecting to the first surface side Z1 on the side in plan view and having the internal space 11K, and the second projecting portion projecting to the second surface side Z2 opposite to the first surface side Z1 and having the internal space 12K. The protrusions 12 are alternately and continuously arranged in different X and Y directions that intersect in plan view, and the first sheet 11 is shaped. In this case, the fiber density of the 1st protrusion part 11 shape | molded along the flow of the hot air W1 corresponding to the hole 112 becomes lower than the 2nd protrusion part 12 shape | molded corresponding to the processus | protrusion 111. FIG.
The arrows in the drawing schematically show the flow of the first hot air W1.

Specific examples of this production method include the following embodiments.
The webs 51 and 52 before being fused are respectively supplied from a card machine (not shown) to a device for shaping the web so as to have a predetermined thickness. In the manufacturing apparatus, the webs 51 and 52 are first transported and fixed in a stacked state on the support 110 (hereinafter, the stacked state is referred to as the web stack 50 or the web 50). The web 51 is on the support 110 side of the shaping apparatus, and the web 52 is laminated on the web 51. The web 51 becomes the first surface side of the nonwoven fabric 10 after shaping.

The webs 51 and 52 are fiber aggregates made of the above-described fiber material before being made into a non-woven fabric, and are in a state where fibers are entangled very loosely. The webs 51 and 52 are obtained by attaching a hydrophilizing agent to the surface of the fiber material.
As said hydrophilizing agent, what is used for this kind of goods can be used arbitrarily. For example, various surfactants can be mentioned as typical ones, and anionic, cationic, zwitterionic and nonionic surfactants can be used.
Preferred surfactants or surfactant combinations include alkyl phosphate potassium salts, polyoxyethylene alkylamides and alkylbetaines, alkyl phosphate potassium salts and alkylsulfonate sodium salts, polyoxyethylene alkylamines and polyglycerol monoalkylates, Polyoxyethylene alkylamide and stearyl phosphate potassium salt, polyoxyethylene alkylamide and polyglycerol monoalkylate, alkylsulfonate sodium salt and stearyl phosphate potassium salt, alkyl ether phosphate potassium salt and polyglycerol fatty acid ester, polyoxy Ethylene alkylamide and dialkylsulfosuccinate sodium salt, polyoxy Ethylene polyoxypropylene modified silicone and dialkyl sulfosuccinate, polyglycerol fatty acid ester and dialkyl sulfosuccinate sodium salt, sorbitan fatty acid ester and dialkyl sulfosuccinate sodium salt, polyoxyethylene alkylamide and polyglycerol fatty acid ester, polyoxyethylene alkyl Amide and sorbitan fatty acid ester, polyoxyethylene alkylamine and sorbitan fatty acid ester, polyoxyethylene polyoxypropylene modified silicone and polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene modified silicone and polyglycerin fatty acid ester, polyoxyethylene polyoxy Propylene-modified silicone and so Tail fatty acid esters, sorbitan fatty acid esters and polyoxyethylene alkyl ethers, polyglycerol fatty acid esters and sorbitan fatty acid esters, polyglycerol fatty acid esters and polyoxyethylene alkyl ethers, and the like. These preferable surfactants and preferable combinations of surfactants only need to contain these surfactants, and may further contain other surfactants and the like.

The web 51 and the web 52 are made different in hydrophilicity from each other in advance, or different in hydrophilicity by a subsequent hot air treatment.
Various combinations of fiber assemblies having different hydrophilicities in advance can be used. Further, even if the same fiber material is used, different hydrophilic agents can be attached to form a fiber assembly having different hydrophilicity. For example, a nonionic surfactant having low hydrophilicity can be added to the web 51 and hydrophilic. A highly functional anionic surfactant or the like can be attached to the web 52. In this case, the hydrophilizing agent may be used in combination with another hydrophilizing agent.

  On the other hand, in order to make the web 51 and the web 52 different in hydrophilicity by the hot air treatment in the subsequent step, when the web 50 is made of the nonwoven fabric 10, the heat-extensible fibers are unevenly distributed on the first surface side. Can be obtained. This is due to the fact that the hydrophilic property is lowered when the heat stretchable fiber is stretched by hot air. The “uneven distribution” of the heat-extensible fibers refers to an aspect in which more heat-extensible fibers are contained on the first surface side than on the second surface side in the nonwoven fabric 10, and the heat-extensible properties on the second surface side. There may be a region where no fiber is contained, and an aspect in which the content of the heat-extensible fiber is gradually reduced from the first surface side to the second surface side, an aspect in which the content is intermittently or multistagely reduced, etc. Including. Typically, a form in which the heat-extensible fibers are contained in the web 51 and not in the web 52, a form in which the web 51 contains more heat-extensible fibers than the web 52, and the like can be given. At least, the content ratio of the heat-extensible fiber in the web 51 is preferably 30% or more, and more preferably 50% or more. By setting it to the above lower limit or more, the contact angle of the fibers on the first surface side Z1 of the nonwoven fabric 10 formed on the web 51 is large, which is preferable because the hydrophilicity is lowered. Thereby, hydrophilic property can be varied between the web 51 and the web 52 by hot air treatment.

  The heat-extensible fiber is a fiber whose length is extended by heating, and examples thereof include a core-sheath type composite fiber that spontaneously extends by changing the crystal state of the resin by heating (hereinafter referred to as heat-extensible fiber). This is called composite fiber.) A preferable heat-extensible conjugate fiber has a first resin component that constitutes a core portion and a second resin component that comprises a polyethylene resin and constitutes a sheath portion, and the first resin component is a second resin component. Has a higher melting point. A 1st resin component is a component which expresses the heat | fever extensibility of this fiber, and a 2nd resin component is a component which expresses heat-fusibility. The 2nd resin component which comprises a sheath part should just exist at least one part of the fiber surface continuously in a length direction.

  The melting points of the first resin component and the second resin component were determined by thermal analysis of a finely cut fiber sample (sample weight 2 mg) using a differential scanning calorimeter (DSC6200 manufactured by Seiko Instruments Inc.) at a heating rate of 10 ° C./min. The melting peak temperature of each resin is measured and defined by the melting peak temperature. When the melting point of the second resin component cannot be clearly measured by this method, the resin is defined as “resin having no melting point”. In this case, the temperature at which the second resin component is fused to such an extent that the strength of the fusion point of the fiber can be measured is used as the temperature at which the molecular flow of the second resin component begins, and this is used instead of the melting point.

When the first resin component and the second resin component have the following orientation index values, the heat-extensible conjugate fiber is stretched by heating. The orientation index is an index of the degree of orientation of the polymer chain of the resin constituting the fiber.
The preferred orientation index of the first resin component in the heat-stretchable conjugate fiber is naturally different depending on the resin used. For example, in the case of a polypropylene resin, the orientation index is preferably 60% or less, more preferably 40% or less. More preferably, it is 25% or less. When the first resin component is polyester, the orientation index is preferably 25% or less, more preferably 20% or less, and still more preferably 10% or less. On the other hand, the second resin component preferably has an orientation index of 5% or more, more preferably 15% or more, and still more preferably 30% or more.

The orientation index of the first resin component and the second resin component is expressed by the following formula (1), where A is the birefringence value of the resin in the heat-extensible conjugate fiber, and B is the intrinsic birefringence value of the resin. expressed.
Orientation index (%) = A / B × 100 (1)
Intrinsic birefringence refers to birefringence in the state where the polymer polymer chains are perfectly oriented. The values are, for example, the first edition of “Plastic Materials in Molding”, and the typical plastic materials used in molding processes (plastics). Edited by the Japan Society for Molding and Processing, Sigma Publishing, published on February 10, 1998).
The birefringence in the heat-extensible composite fiber is measured under polarization in a direction parallel to and perpendicular to the fiber axis by attaching a polarizing plate to an interference microscope. As the immersion liquid, a standard refraction liquid manufactured by Cargille is used. The refractive index of the immersion liquid is measured with an Abbe refractometer. From the interference fringe image of the composite fiber obtained by the interference microscope, the refractive index in the direction parallel and perpendicular to the fiber axis is obtained by the calculation method described in the following document, and the birefringence that is the difference between the two is calculated.
“Fiber structure formation in high-speed spinning of core-sheath type composite fiber”, page 408 (Journal of the Fiber Society, Vol. 51, No. 9, 1995)

The core-sheath type heat-extensible conjugate fiber may be a concentric core-sheath type, an eccentric core-sheath type, a side-by-side type, or a concentric core-sheath type.
The 2nd resin component which comprises a sheath part contains a polyethylene resin. The polyethylene resin that constitutes the sheath part imparts heat-fusibility to the core-sheath-type composite fiber and plays the role of incorporating the aforementioned hydrophilizing agent during heat treatment. As the polyethylene resin, low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), etc. can be used, but the density is 0.935 to 0.965 g / cm ^3. It is preferably a density polyethylene. The resin component constituting the sheath is preferably a polyethylene resin alone, but other resins can also be blended. Other resins to be blended include polypropylene resin, ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl alcohol copolymer (EVOH), and the like. However, as for the resin component which comprises a sheath part, it is preferable that 50 mass% or more in the resin component of a sheath part is 70-100 mass% especially polyethylene resin.
The polyethylene resin constituting the sheath part preferably has a crystallite size of 100 to 200 mm. When the crystallite size is 100 mm or more, the hydrophilizing agent is easily taken into the fiber from the surface during heat treatment, and the selection of the hydrophilizing agent to be used is wide. Thereby, the hydrophilic property of desired parts, such as this fiber and a web obtained using this, a nonwoven fabric, etc. can be reduced easily.
From the viewpoint of reliably causing a change in the hydrophilicity of the fiber surface, the crystallite size is preferably 100 to 200 mm, and more preferably 115 to 180 mm. The upper limit value of 200 mm of the crystallite size is determined from the viewpoint of mechanical properties such as tensile strength and elongation at break. If the crystallite size is within 200 mm, the number of crystals is not reduced and the mechanical properties are not lowered.

[Method for measuring crystallite size of polyethylene resin]
The crystallite size is calculated from the half width measured by the powder X-ray diffraction method by the Serrer equation. As a calculation method, RINT-2500 manufactured by Rigaku Corporation is used, and the peak of the plane index (110) of PE is calculated by the attached crystallite size calculation program JADE 6.0. Specific conditions are a CuKα ray (wavelength 0.154 nm) as a radiation source, a generated voltage and current of 40 kV · 120 mA, and a sweep rate of 10 ° / min. The sample is placed at the time of measurement by attaching a fiber bundle so as to be parallel to the length direction of the slit of the sample holder, and making the fiber bundle perpendicular to the incident direction of X-rays.

A core part is a part which provides intensity | strength to a core-sheath-type composite fiber, As a 1st resin component which comprises a core part, the resin component whose melting | fusing point is higher than a polyethylene resin can be especially used without a restriction | limiting. Examples thereof include polyolefin resins such as polypropylene (PP) (excluding polyethylene resins), polyester resins such as polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). Furthermore, a polyamide-type polymer, the copolymer of 2 or more types of the resin component mentioned above, etc. can be used.
Of these combinations, it is preferable to use polypropylene (PP) or polyethylene terephthalate (PET). A plurality of types of resins can be blended and used. In this case, the melting point of the core is the melting point of the resin having the highest melting point.
Moreover, it becomes easy to manufacture a nonwoven fabric that the difference between the melting point of the first resin component constituting the core part and the second resin component constituting the sheath part (the former-the latter) is 20 ° C. or more. This is preferable. The difference in melting points is preferably within 150 ° C.

In this production example, the first hot air W1 is then blown onto the web laminate 50 on the support 110 (the state shown in FIG. 4 (1)). That is, the 1st hot air W1 is sprayed with respect to the web laminated body 50 from the side used as the 2nd surface in the nonwoven fabric 10. FIG. And the web laminated body 50 is shaped so that it may follow the shape of the support body 110 (state of FIG. 4 (2)). The temperature of the first hot air W1 at this time is 0 ° C. to 70 ° C. lower than the melting point of the thermoplastic fiber constituting the web laminate 50 in consideration of a general fiber material used in this type of product. Is preferable, and it is more preferable that it is 5 to 50 degreeC low. Although the wind speed of the 1st hot air W1 is based also on the height of the processus | protrusion 111 of the support body 110, it sets to 20-150 m / s from a viewpoint of shaping property and texture, Preferably it sets to 30-100 m / s. Is done. When the wind speed is slower than this lower limit, the film is not sufficiently shaped, and the effects of cushioning properties, excrement stock properties and breathability are not fully exhibited. If the wind speed exceeds this upper limit value, an opening will occur in the top portion 12T of the second projecting portion 12, it will be easily crushed, and the effects of cushioning, excrement stocking and breathability will not be fully exhibited. Furthermore, it becomes easy for excrement to go back through the opening.
In this way, the web laminate 50 is shaped into an uneven shape.

  In addition, the height of the protrusion 111 of the support 110 is appropriately determined depending on the thickness of the entire sheet to be shaped and the layer thickness of the sheet. For example, it is set to 1 mm to 10 mm, preferably 2 mm to 8 mm, and more preferably 2 mm to 8 mm.

Next, as shown in FIG. 4 (3), the fibers of the web laminate 50 are fused by blowing the second hot air W2 at a temperature at which the fibers can be appropriately fused. Also in this case, similarly to the first hot air W1, the second hot air W2 is blown from the side that becomes the second surface of the nonwoven fabric 10 to the web laminate 50. The temperature of the second hot air W2 at this time is 0 ° C. or more and 70 ° C. or less with respect to the melting point of the thermoplastic fiber constituting the web laminate 50 in consideration of a general fiber material used for this type of product. It is preferably high in the range, and more preferably high in the range of 5 ° C or higher and 50 ° C or lower.
Although the wind speed of the 2nd hot air W2 is based also on the height of the protrusion 111 of the support body 110, it is set to 1 m / s or more and 10 m / s or less, Preferably it is set to 3 m / s or more and 8 m / s or less. If the wind speed of the second hot air W2 is too slow, heat cannot be transferred to the fibers, the fibers are not fused together, and the uneven shape is insufficiently fixed. On the other hand, if the wind speed is too high, the fiber will be too hot and the texture will tend to be poor.

  As the thermoplastic fiber, the fiber described above is used. For example, when a composite fiber containing a low melting point component and a high melting point component is used as the thermoplastic fiber, the temperature of the second hot air W2 sprayed on the web laminate 50 is not less than the melting point of the low melting point component and less than the melting point of the high melting point component. It is preferable that More preferably, the temperature is at least 10 ° C lower than the melting point of the high melting point component, more preferably at least 5 ° C higher than the melting point of the low melting point component, and more preferably at least 20 ° C lower than the melting point of the high melting point component. .

  The nonwoven fabric 10 is produced as described above. The convex part formed by moving the web fibers through the holes 112 to form the first protruding part 11 of the nonwoven fabric 10, and the convex part formed along the protruding part 111 is the nonwoven fabric 10. It becomes the 2nd protrusion part 12. FIG. The lower surface in FIG. 4 is the first surface side, and the opposite surface is the second surface side. That is, in the nonwoven fabric 10, the 1st surface side is the side by which the said support body was distribute | arranged, and the 2nd surface side is the side by which the said hot air was sprayed.

  In the manufacturing method, considering continuous production, the manufacturing apparatus (not shown) is a conveyor type or drum type capable of transporting the support 110, and the first sheet on which the uneven shape is fixed on the support. An example is a mode in which 11 is peeled off from the support and then wound up in a roll shape (not shown).

  In the above manufacturing method, the thickness of each sheet is appropriately determined depending on the height of the protrusion 111 and the wind speed. For example, when the height of the protrusion 111 is increased, the thickness of the sheet is increased, and when it is decreased, the thickness of the sheet is decreased. On the other hand, when the wind speed is increased, the thickness of the sheet is increased, and when the wind speed is decreased, the thickness of the sheet is decreased. Further, when the height of the protrusion 111 is increased, the fiber density of the sheet is decreased, and when it is decreased, the fiber density of the sheet is increased. On the other hand, when the wind speed is increased, the fiber density of the sheet is decreased, and when it is decreased, the fiber density of the sheet is increased.

Under any of the above-described wind speed conditions, the hot air passes through the holes 112 of the support 110, whereby the web laminate 50 becomes bulky at the same time as shaping. In particular, the fiber of the web 51 on the support side is in a coarse fiber density state due to the influence of hot air blown through.
Furthermore, when the method of adding a hydrophilic property difference by including a heat-extensible fiber in the web 51 is adopted, the inter-fiber distance of the portion is widened by the thermal extension of the fiber, resulting in a coarser fiber density state. Accordingly, the fiber density of the first surface side z1 of the first projecting portion 11 _{(r 11a)} and the fiber density of the second surface side z2 _{(r 11b),} but a relationship of _r 11a _{<r 11b.}

The nonwoven fabric 10 of the present invention can be used for various other applications. For example, it can be suitably used as a surface sheet for absorbent articles such as disposable diapers for adults and infants, sanitary napkins, panty liners, urine absorption pads and the like. Furthermore, since the both surfaces of the nonwoven fabric 10 are excellent in air permeability, liquid diffusibility, deformation characteristics at the time of pressing force, etc. due to the concavo-convex structure, between the surface sheet such as diapers and sanitary products and the absorbent body It can also be used as a sub-layer interposed between them, an absorbent covering sheet (core wrap sheet), and the like. In addition, the form utilized as a surface sheet, gathers, an exterior sheet, and a wing of an absorbent article is also mentioned. Furthermore, the form utilized as a covering sheet | seat of a wiping wipe sheet | seat, a cleaning sheet | seat, a filter, and a heating tool is also mentioned.
The following nonwoven fabrics and the like are further disclosed with respect to the above-described embodiment.

<1> A first projecting portion projecting on the first surface side of the sheet-like nonwoven fabric in plan view and having an internal space, and a second projecting surface projecting on the second surface side opposite to the first surface side and having an internal space. Two projecting portions, and having a wall portion of an annular structure between the top portion of the first projecting portion and the opening portion of the internal space, and the first and second projecting portions are made of the nonwoven fabric. A non-woven fabric that is continuously arranged alternately in different directions intersecting in plan view, and the hydrophilicity of the fibers on the first surface side is lower than the hydrophilicity of the fibers on the second surface side.

<2> The nonwoven fabric according to <1>, wherein the first surface side has a relatively low hydrophilicity within the layer thickness of the sheet with respect to the second surface side.
<3> The nonwoven fabric according to <1> or <2>, wherein there is a hydrophilic gradient that increases from the first surface side toward the second surface side.
The difference of the contact angle of the water with respect to the fiber in <4> said 1st surface side and said 2nd surface side is 7 to 10 degree | times, Any one of said <1>-<3>. Non-woven fabric.
<5> The difference in the contact angle of water with respect to the fibers on the first surface side and the second surface side is 8 degrees or more and 9 degrees or less, according to any one of the above items <1> to <4>. Non-woven fabric.
<6> The nonwoven fabric according to any one of <1> to <5>, wherein a contact angle of water with respect to fibers in the vicinity of the surface of the first surface is 74 degrees or greater and 80 degrees or less.
<7> The nonwoven fabric according to any one of <1> to <6>, wherein a contact angle of water with respect to fibers in the vicinity of the surface of the second surface is 64 degrees or greater and 73 degrees or less.
<8> The nonwoven fabric according to any one of <1> to <7>, wherein the fiber density (r1) of the first protrusion is lower than the fiber density (r2) of the second protrusion.
<9> the first projecting portion of the fiber density 30 yarns / mm ² or more 130 present / mm ² or less is the <1> to <8> nonwoven fabric according to any one of the.
<10> The nonwoven fabric according to any one of <1> to <9>, wherein the fiber density of the second protrusion is from 250 / mm ^{2 to} 500 / mm ² .
<11> The nonwoven fabric according to any one of <1> to <10>, wherein a difference between a fiber density of the first protrusion and a fiber density of the second protrusion is 150 pieces / mm ² or more.
<12> The fiber constituting the wall of the first protrusion is fiber-oriented in the direction connecting the top of the first protrusion and the edge of the opening at any location over the entire circumference of the wall. The nonwoven fabric according to any one of <1> to <11>, which has
<13> The fiber constituting the wall portion of the second protrusion is fiber-oriented in the direction connecting the top of the second protrusion and the edge of the opening at any location over the entire circumference of the wall portion. The nonwoven fabric according to any one of <1> to <12>, which has
<14> The nonwoven fabric according to any one of <1> to <13>, wherein hydrophilic agents having different hydrophilicity are attached to the fibers on the first surface side and the fibers on the second surface side.
<15> The nonionic surfactant according to any one of <1> to <14>, wherein the nonionic surfactant is attached to the first surface side fiber, and the anionic surfactant is attached to the second surface side fiber. Non-woven fabric.
<16> The nonwoven fabric according to any one of <1> to <15>, wherein the heat-extensible fibers are unevenly distributed on the first surface side.
<17> The nonwoven fabric according to <16>, wherein the second surface side has a region containing no heat-extensible fibers.
<18> The nonwoven fabric according to <16> or <17>, wherein the content of the heat-extensible fiber is gradually reduced from the first surface side to the second surface side.
<19> The nonwoven fabric according to <1> to <18>, wherein the nonwoven fabric is a nonwoven fabric produced by disposing a support on the first surface side and blowing hot air from the second surface side.
<20> An absorptive article using the nonwoven fabric according to any one of <1> to <19> as a skin surface side.
<21> An infant diaper that uses the non-woven fabric according to any one of <1> to <19> as a skin surface side.
<22> The method for producing a nonwoven fabric according to <1> to <18>, wherein a web is provided from a card machine on a support in which a number of protrusions and holes are alternately arranged in different directions, and the nonwoven fabric is provided. The manufacturing method of the nonwoven fabric which shape | molds by blowing a 1st hot air from the side used as the 2nd surface in this, and also fuse | melts fibers by blowing a 2nd hot air.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is limited and interpreted by these Examples.

[Example 1]
(1) Preparation of surface sheet As the web 51 and the web 52, a non-woven fabric specimen c1 was prepared using a 2.4 dtex × 51 mm core-sheath type composite fiber having a core made of polyethylene terephthalate and a sheath made of polyethylene. For the core-sheath composite fibers used for the webs 51 and 52, the hydrophilizing agent was adjusted so that the contact angle became the value in the table. The web 51 and the web 52 were supplied from the card machine to the shaping device so that the basis weight was 15 g / m ² . In the shaping apparatus, the web 51 and the web 52 were laminated in this order on the support 110 having a large number of protrusions and air permeability, and fixed as a web laminate 50. The MD pitch in the plan view of the protrusion 111 of the support 110 was 8 mm, the CD pitch was 5 mm, and the height of the protrusion 111 was 7.5 mm. Moreover, the hole diameter of the hole 112 in the support body 110 was 2.8 mm.
Next, the web laminate 50 was shaped along the protrusions 111 on the support 110 by blowing the first hot air W1 (temperature 130 ° C., wind speed 50 m / s) onto the web laminate 50 on the support 110. . Next, it switched to the 2nd hot air W2 of the temperature of 145 degreeC, and the wind speed of 1.1 m / s, the fibers of each core-sheath structure were fused together, and the shaping shape was fixed. The processing speed was 50 m / min. In this way, a nonwoven fabric test body c1 was produced.
The basis weight of the nonwoven fabric test body c1 of Example 1 was 30.1 g / m ² , and the sheet thickness was 3.9 mm. Moreover, the contact angle of the fiber on the first surface side was 76.7 degrees, and the contact angle of the fiber on the second surface side was 68.5 degrees. Fiber density of the nonwoven fabric specimen c1 is first protrusion 92 present / mm ^2, the second protruding portion was 446 present / mm ^2. In addition, the said contact angle and fiber density were measured with the above-mentioned measuring method.
(2) Preparation of diapers The surface sheet is removed from a commercially available baby diaper (trade name “Merry's Sarah Air-Through M Size” 2012) manufactured by Kao Corporation. An infant diaper for evaluation was obtained by fixing.

[Example 2]
In Example 2, the resin composition of the core-sheath composite fiber used for the webs 51 and 52 was the same as that in Example 1, but the hydrophilizing agent was adjusted so that the contact angle became the value in the table. Other than that, the nonwoven fabric test body c2 was produced on the conditions similar to the said Example 1. FIG. The basis weight of the nonwoven fabric test body c2 of Example 2 was 29.7 g / m ² , and the sheet thickness was 4.0 mm. Moreover, the contact angle of the fiber on the first surface side was 78.0 degrees, and the contact angle of the fiber on the second surface side was 70.7 degrees. Fiber density of the nonwoven fabric specimen c2, the first protrusion 93 present / mm ^2, the second protruding portion was 441 present / mm ^2.
The diaper was produced using the nonwoven fabric specimen c2 instead of the nonwoven fabric specimen c1 of the example.

[Example 3]
In Example 3, as the web 51, a core / sheath composite fiber of 2.4 dtex × 51 mm whose core is made of polyethylene terephthalate and whose sheath is made of polyethylene is 50%, whose core is made of polypropylene (PP) and whose sheath is made of polyethylene (PE). A fiber material mixed with 50% extensible core-sheath type composite fiber was used. On the other hand, as the web 52, a fiber material of 2.4 dtex × 51 mm 100% core-sheath type composite fiber in which the same core used for the web 51 is made of polyethylene terephthalate and the sheath is made of polyethylene was used. For the core-sheath composite fibers used for the webs 51 and 52, the hydrophilizing agent was adjusted so that the contact angle became the value in the table. Otherwise, a nonwoven fabric specimen c3 was produced under the same conditions as in Example 1 above. The basis weight of the nonwoven fabric test body c3 of Example 3 was 29.9 g / m ² , and the sheet thickness was 3.5 mm. Further, the contact angle of the fiber on the first surface side was 76.5 degrees, and the contact angle of the fiber on the second surface side was 67.9 degrees. Fiber density of the nonwoven fabric specimen c3, the first protrusion 59 present / mm ^2, the second protruding portion was 426 present / mm ^2.
The diaper was produced using the nonwoven fabric test body c3 instead of the nonwoven fabric test body c1 of the example.

[Example 4]
In Example 4, as the web 51, a core / sheath composite fiber of 2.4 dtex × 51 mm whose core is made of polyethylene terephthalate and whose sheath is made of polyethylene is 70%, whose core is made of polypropylene (PP), and whose sheath is made of polyethylene (PE). A fiber material mixed with 30% extensible core-sheath type composite fiber was used. For the core-sheath composite fibers used for the webs 51 and 52, the hydrophilizing agent was adjusted so that the contact angle became the value in the table. Otherwise, a nonwoven fabric specimen c4 was produced under the same conditions as in Example 3. The basis weight of the nonwoven fabric test body c4 of Example 4 was 30 g / m ² , and the sheet thickness was 3.7 mm. Moreover, the contact angle of the fiber on the first surface side was 74.6 degrees, and the contact angle of the fiber on the second surface side was 67.4 degrees. Fiber density of the nonwoven fabric specimen c4, the first protrusion 66 present / mm ^2, the second protruding portion was 433 present / mm ^2.
The diaper was produced using the nonwoven fabric test body c4 instead of the nonwoven fabric test body c1 of the example.

[Comparative Example 1]
In Comparative Example 1, a non-woven fabric test body having a streak-like uneven shape was produced by the manufacturing method described in Example 1 of JP-A-2008-25081 (Patent Document 1). The basis weight of the nonwoven fabric test body d1 of Comparative Example 1 was 27 g / m ² and the sheet thickness was 1.3 mm. Moreover, the contact angle of the fiber on the first surface side was 84.5 degrees, and the contact angle of the fiber on the second surface side was 79.4 degrees. The fiber density part of the convex part of the nonwoven fabric test body d1 was 65 / mm < ² >, and the opening was formed in the recessed part.
The diaper was produced using the nonwoven fabric test body d1 instead of the nonwoven fabric test body c1 of the example.

[Comparative Example 2]
Comparative Example 2 was a non-woven fabric having no irregularities, and a non-woven fabric test body d2 having different hydrophilicity on both surfaces was prepared. Specifically, a web sheet having the same fiber configuration as in Example 1 was prepared and heat-treated with hot air at 139 ° C. and a wind speed of 1.5 m / sec.
The basis weight of the nonwoven fabric test body d2 of Comparative Example 2 was 29.6 g / m ² , and the sheet thickness was 2.3 mm. Further, the contact angle of the fiber on the first surface side was 76.5 degrees, and the contact angle of the fiber on the second surface side was 68.4 degrees. The fiber density part of the nonwoven fabric test body d2 was 244 fibers / mm ² .
The diaper was produced using the nonwoven fabric test body d2 instead of the nonwoven fabric test body c1 of the example.

[Comparative Example 3]
In Comparative Example 3, a nonwoven fabric specimen was produced by the method described in Example 1 of JP-A-03-137258. The basis weight of the nonwoven fabric test body d3 of Comparative Example 3 was 27 g / m ² , and the sheet thickness was 5.5 mm. Moreover, the contact angle of the fiber on the first surface side was 76.9 degrees, and the contact angle of the fiber on the second surface side was 76.3 degrees. The fiber density part of the convex part of the nonwoven fabric test body d3 was 80 / mm < ² >, and the opening was formed in the recessed part.
The diaper was produced using the nonwoven fabric test body d3 instead of the nonwoven fabric test body c1 of the example.

  Next, the evaluation method will be described. The following measurement test was performed using a nonwoven fabric test body or a diaper.

<Measurement of basis weight>
The basis weight of each nonwoven fabric specimen was measured by the following method. First, the nonwoven fabric test body was cut into a size of 250 mm × 200 mm, and this was used as a measurement piece. The measurement piece was placed on an electronic balance (regardless of manufacturer). The weight in this state was measured, and the weight was divided by the area to obtain the basis weight (g / m ² ). As measured values, three points were measured and the average value was adopted.

<Measurement of sheet thickness>
Using a KES compression tester (KES FB-3, manufactured by Kato Tech Co., Ltd.), each nonwoven fabric test specimen was evaluated for compression characteristics up to 5.0 × 10 ³ Pa in the normal mode, and at a minute pressure (0. The thickness of 05 × 10 ³ Pa) was read from the chart. As measured values, three points were measured and the average value was adopted.

<Measurement of soft stool adhesion and stool expansion area>
Place a baby diaper (test body) horizontally, pressurize in the center (urination point) without pressure, artificial loose stool (bentonite: glycerin: water: emulgen 130K (trade name, surfactant manufactured by Kao Corporation) = 28: 14: 114: 14 was mixed, and the viscosity was adjusted to 300 mPa · s) at a rate of 2 g / second, and 10 g was injected and allowed to stand for 5 minutes. Thereafter, the transparent PET sheet was gently placed on the surface of the surface sheet, and a weight was placed on the transparent PET sheet so as to be 3.5 × 10 ³ Pa and pressed for 5 minutes. Thereafter, the weight is removed, the transparent PET sheet is taken out, and the weight of the pseudo PET attached to the transparent PET sheet is calculated by measuring the weight of the transparent PET sheet before and after pressurization. did. Moreover, the area where the pseudo-soft stool after pressurization spread was measured and defined as the soft stool diffusion area.

<Measurement of strike-through>
The liquid strike-through indicates the time (seconds) required for a predetermined amount of physiological saline to pass from the front surface to the back surface of the sheet. Measured based on the test method “153.0-02 REPEATED LIQUID STRIKE-THROUGH TIME” defined by EDANA (European Disposables And Nonwovens Association) using a tester LISTER (trade name) manufactured by LENZING . Specifically, ten sheets of dedicated filter paper were placed on the pedestal of the testing machine, and the nonwoven fabric test specimen was placed thereon. Next, a strike-through plate having electrodes was placed on the non-woven fabric specimen, and 5 ml was added from a liquid inlet connected to the plate. The tester was then turned on. The test machine measured the time from when the liquid touched the electrode until the liquid passed through the non-woven fabric and its water level dropped and was not in contact with the electrode. This measurement was performed N = 3 times, and the average value was recorded as a strike-through measurement value.

  Table 1 shows the measurement results and evaluation results for each of the above evaluation items.

  As is clear from the evaluation results shown in Table 1, the non-woven fabric specimens c1 to c3 of Examples 1 to 4 have a reduced amount of loose stool and a stool diffusion area compared to the specimens d1 to d3 of the comparative example. And it turned out that it is excellent in the passage speed of a liquid.

DESCRIPTION OF SYMBOLS 10 Nonwoven fabric 11 1st protrusion part 11T 1st protrusion part top part 11K Internal space 11H Opening part 11W Wall part 12 2nd protrusion part 12T 2nd protrusion part top part 12K Internal space 12H Opening part 12W Wall part 16 1st edge part 17 2nd Edge Z1 1st surface side Z2 2nd surface side

Claims (5)

  A first projecting portion projecting on the first surface side of the sheet-like nonwoven fabric in plan view and having an internal space, and a second projecting portion projecting on the second surface side opposite to the first surface side and having an internal space And having a wall portion of an annular structure between the top of the first protrusion and the opening of the internal space, the first and second protrusions intersecting the nonwoven fabric in plan view The nonwoven fabric is arranged alternately and continuously in different directions, and the hydrophilicity of the fibers on the first surface side is lower than the hydrophilicity of the fibers on the second surface side. The nonwoven fabric according to claim 1, wherein the fiber density (r ₁ ) of the first protrusion is lower than the fiber density (r ₂ ) of the second protrusion.   The nonwoven fabric according to claim 1, wherein the heat-extensible fibers are unevenly distributed on the first surface side.   The nonwoven fabric according to any one of claims 1 to 3, wherein the nonwoven fabric is a nonwoven fabric produced by disposing a support on the first surface side and blowing hot air from the second surface side.   The absorbent article which uses the nonwoven fabric of any one of Claims 1-4 as the skin surface side as the 1st surface side.

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