JP2010063943A - Absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent article which gives no sticky feeling and can be comfortably used. <P>SOLUTION: The rectangular absorbent article 1 includes a surface sheet 10 on a skin contact face side. The surface sheet 10 is made of an unwoven fabric having furrow parts 20 and grooves 30 extending in the longitudinal direction of the absorbent article 1 alternately and has an opening 31 in the grooves 30. The contact angle of the constituent fiber of the unwoven fabric is 60-85°. On the skin non-contact face side of the surface sheet 10, a low density sheet 12 having a low fiber density compared to the grooves 30 is arranged adjacent to the surface sheet 10. It is preferable that the fiber density of the furrow part 20 is higher than that of the grooves 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an absorbent article such as a cage sheet (panty liner) and a sanitary napkin.

  Conventionally, bodily fluid absorbent articles such as cage sheets and sanitary napkins are composed of a liquid-permeable top sheet, a liquid-impervious back sheet, and a liquid-absorbent core interposed between these two sheets. . As the surface sheet, a nonwoven fabric or a perforated synthetic resin film is used. And as a surface sheet, the proposal which improves absorptivity is made by using what gave various shapes, such as a hole sheet which has a liquid introduction pipe, and a sheet which has a slotted structure (for example, patent documents). 1). Further, by arranging a hydrophilic fiber sheet between the surface sheet and the liquid-absorbent core, and applying a specific hydrophilic gradient to the surface sheet and the hydrophilic fiber sheet, the body fluid once absorbed is the surface sheet. Proposals have also been made to suppress the phenomenon of liquid reversion (liquid return) and liquid flow on the top sheet (see, for example, Patent Document 2).

JP 2007-175515 A Japanese Patent Laying-Open No. 2005-87659

  In Patent Document 1, as the top sheet, the top sheet protrudes upward from the liquid-absorbent core and extends in the first direction of the article, and is arranged at a given distance in the second direction of the article perpendicular to the first direction. A body fluid that employs a surface member having a plurality of protrusions, a plurality of recesses extending between the protrusions in the lateral direction, and a large number of apertures that can pass through the body fluid in the thickness direction. A treated article is described. However, the bodily fluid treatment article described in Patent Document 1 has high liquid diffusibility due to the fact that the convex portion extends in one specific direction of the article. It is easy to get into the top of the convex part which touches the wearer's skin at the time of wearing or the vicinity thereof. In addition, the high fiber density of the lower layer of the absorbent core located below the surface member facilitates the entry of the liquid into the top of the convex part. For this reason, the body fluid treatment described in Patent Document 1 The article has a problem that stickiness is likely to occur.

  In Patent Document 2, imparting higher hydrophilicity to the back side of the top sheet than the front side, and higher hydrophilicity to the surface of the hydrophilic fiber sheet on the liquid absorbent core side than the surface on the top sheet side. It is described that the degree is given. However, in the absorbent article described in Patent Document 2, the hydrophilic gradient is reversed between the upper side and the lower side in the thickness direction with the back surface side of the top sheet as a boundary ([0032] of Patent Document 2 and FIG. 3 and FIG. 3). In particular, there is a problem that movement of the body fluid having a relatively high viscosity such as menstrual blood in the thickness direction is hindered, and that the liquid spreads at the boundary and stickiness due to the liquid staying easily occurs. there were.

  An object of the present invention is to provide an absorbent article that does not feel sticky and can be used comfortably.

  The present invention relates to a vertically long absorbent article having a surface sheet on the skin contact surface side, wherein the surface sheet alternately has ridges and grooves extending in the longitudinal direction of the absorbent article and is opened in the groove. A low-density sheet comprising a non-woven fabric having holes, the contact angle of the constituent fibers of the non-woven fabric is 60 to 85 °, and the non-skin contact surface side of the top sheet is low in fiber density compared to the groove portion, The object is achieved by providing an absorbent article disposed adjacent to the top sheet.

  The absorbent article of the present invention has excellent liquid absorbency and can absorb and hold highly viscous body fluids such as menstrual blood so as not to cause discomfort to the wearer. The feeling of use is good.

FIG. 1 is a plan view showing a skin contact surface side (surface sheet side) of a cage sheet according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a cross section taken along line II in FIG. FIG. 3 is an enlarged schematic cross-sectional view showing a part of FIG. 2 in an enlarged manner. FIG. 4 is a view corresponding to FIG. 3 of another embodiment of the present invention. FIG. 5 is a perspective view schematically showing an enlarged main part of the top sheet used for the cage sheet shown in FIG. FIG. 6 is a schematic diagram of a cross section taken along line II-II in FIG. FIG. 7 is a view corresponding to FIG. 6 showing another cross-sectional state of the top sheet used in the cage sheet shown in FIG. FIG. 8 is a schematic view showing an example of an apparatus for producing the top sheet shown in FIG. FIG. 9 is a perspective view showing the fluid-permeable support in FIG. FIG. 10 is a schematic diagram showing a process of manufacturing a top sheet using the apparatus shown in FIG. FIG. 11 is a diagram for explaining a method of measuring a contact angle, and (a) and (b) are diagrams in which the contact angle is preferably measured. In addition, (a ') and (b') are figures which show the fiber after the droplet on a fiber evaporates, and are used in order to measure the tangent of the fiber surface in a boundary part with a water droplet.

  Hereinafter, the absorptive article of the present invention is explained based on the desirable embodiment with reference to drawings. FIG. 1 shows a plan view of a cage sheet, which is an embodiment of the absorbent article of the present invention, as seen from the topsheet side. FIG. 2 is a diagram schematically showing a cross section taken along line II in FIG.

  As shown in FIG. 1, the cage sheet 1 of the present embodiment has a vertically long shape in plan view, and a central portion in the longitudinal direction is bound inward as a whole. The cage sheet 1 includes a top sheet 10 positioned on the skin contact surface side and a back sheet 11 positioned on the non-skin contact surface side. On the non-skin contact surface side of the top sheet 10, a low-density sheet 12 described later is arranged adjacent to the top sheet 10. That is, the low density sheet 12 is disposed between the two sheets 10 and 11. The low density sheet 12 has a vertically long shape in plan view.

  The top sheet 10 and the back sheet 11 extend outward from the outer peripheral edge of the low-density sheet 12, and the extended sheets 10 and 11 are joined to each other by heat treatment to form a seal portion 15. ing. The seal portion 15 is formed over the entire outer peripheral edge of the cage sheet 1. An adhesive portion (not shown) for fixing the cage sheet 1 to the underwear is provided on the non-skin contact surface in the center region in the width direction of the cage sheet 1, that is, the surface of the back sheet 11. It is formed to extend in the longitudinal direction.

  In this specification, the “longitudinal direction” is a direction along the long sides of the absorbent article or various members constituting the absorbent article (the vertical direction in FIG. 1), and the “width direction” is orthogonal to the longitudinal direction. Direction (left and right direction in FIG. 1). Further, the “skin contact surface” is a surface directed to the skin side of the wearer when wearing the absorbent article in various members constituting the absorbent article or the absorbent article, and the “non-skin contact surface” It is a surface directed to the underwear side (the side opposite to the wearer's skin side) when the absorbent article is worn, in the absorbent article or various members constituting the absorbent article.

  FIG. 5 shows an enlarged view of a main part of the top sheet 10. 6 is a cross-sectional view taken along line II-II in FIG. In FIG. 5, the direction indicated by Y is the longitudinal direction of the raised sheet 1, and the direction indicated by X is the width direction of the raised sheet 1. The top sheet 10 shown in FIGS. 5 and 6 has a first surface 10a and a second surface 10b opposite to the first surface 10a. The 1st surface 10a is a surface which faces a wearer's skin side, when the surface sheet 10 is integrated in absorbent articles, such as a cage sheet, a sanitary napkin, and a disposable diaper. The second surface 10b is a surface facing the low density sheet 12 side. The top sheet 10 is made of a non-woven fabric having alternating ridges 20 and grooves 30 extending in the longitudinal direction Y of the cage sheet 1 and having openings 31 in the grooves 30. The eaves part 20 and the groove part 30 are alternately arranged over the direction X orthogonal to the direction Y in which they extend.

  The collar portion 20 is filled with the constituent fibers of the topsheet 10. That is, there is no cavity in the collar portion 20. Similarly, a portion of the groove portion 30 where an opening 31 described later is not formed is filled with constituent fibers of the topsheet 10. However, as will be described later, the fiber amount of the flange portion 20 is different from the fiber amount of the groove portion 30, and the fiber amount of the flange portion 20 is substantially larger than that of the groove portion 30.

  The flange portion 20 is configured from a relatively thick portion of the topsheet 10, and the groove portion 30 is configured from a relatively thin portion of the topsheet 10. As a result, the substantial thickness of the flange portion 20 is larger than the thickness of the groove portion 30. Here, the substantial thickness means not the length (apparent thickness) from the back surface of the top sheet 10 to each uppermost part, but the length of the portion where the fibers of the top sheet 10 are present.

  As shown in FIG. 6, in the cross section in the direction orthogonal to the extending direction (the direction indicated by X in the drawing), the flange portion 20 has a smooth curve that is convex upward on the first surface 10 a side. It has a contour to draw. The first surface 10a side of the flange portion 20 is raised higher than the second surface 10b side, and this is periodically continuous. Thus, the first surface 10a side has a waveform shape along the X direction. Therefore, when the 1st surface 10a side of the surface sheet 10 touches a wearer's skin, the top part of the collar part 20 and the area | region of the vicinity will contact partly, and the stickiness by the stuffiness resulting from a full surface contact Feeling and irritation caused by rubbing are reduced. Moreover, it becomes difficult for the liquid excreted from the wearer to adhere to the wearer's skin.

  On the other hand, the second surface 10b side has a contour that draws a smooth and gentle curve convex downward. Therefore, the part located in the collar part 20 among the opposed surfaces of the top sheet 10 to the low density sheet 12 comes into contact with the low density sheet 12 disposed on the lower side of the top sheet 10 by the surface. . As a result, the liquid excreted in the topsheet 10 can pass through the flange 20 in the topsheet 10 and smoothly transition to the low-density sheet 12. As a result, the first surface 10a of the topsheet 10 has a smooth and dry feeling.

  The shape of the collar portion 20 is not limited to the above-described shape. For example, as shown in FIG. 7A, the second surface 10b side has a contour that draws a smooth and gentle curve upward. Alternatively, as shown in FIG. 7B, the second surface 10b side may be flat. Such a difference in shape mainly depends on the manufacturing conditions of the topsheet 10.

  As shown in FIG. 6, the flange portion 20 has a top portion 21 on the first surface 10 a side in the cross section in the X direction, and the substantial thickness is the largest at this portion. Then, with respect to the X direction, the substantial thickness gradually decreases as the distance from the top portion 21 increases. Therefore, when the surface sheet 10 is seen along the X direction, the substantial thickness is periodically changed. Although not shown in the drawing, the flange portion 20 has substantially the same thickness at the top portion 21 at any position in the extending direction (in FIG. 6, the direction orthogonal to the paper surface). In the topsheet 10 of the present embodiment, there is no clear boundary between the flange portion 20 and the groove portion 30, and in general, a portion having the smallest substantial thickness located between the two top portions 21 adjacent to each other in the X direction and A portion in the vicinity thereof becomes the groove 30. When the boundary between the flange portion 20 and the groove portion 30 is clearly defined, the position of the apparent thickness at the top portion 21 of the flange portion 20 is defined as the boundary portion between the flange portion 20 and the groove portion 30.

  The apparent thickness of the collar portion 20 is preferably 0.3 to 5 mm, more preferably 0.5 to 2.5 mm, from the viewpoint of improving the touch of the topsheet 10. The height difference D (see FIG. 6) between the flange portion 20 and the groove portion 30 is preferably 0.1 to 3 mm from the viewpoint of enhancing the cushioning property and air permeability of the topsheet 10 and controlling the diffusion of the liquid. 3-2 mm is more preferable. The thickness and height difference D of the flange part 20 and the groove part 30 are measured by using a microscope VH-8000 (manufactured by Keyence) and observing the cross section of the topsheet 10 at 50 to 200 times. The cross section is obtained by cutting the top sheet 10 using a feather razor (part number FAS-10, manufactured by Feather Safety Razor Co., Ltd.).

  The width of the heel portion 20 in the X direction of the topsheet 10 is preferably 1 to 10 mm, and more preferably 2 to 5 mm, from the viewpoint of touch and absorbency. From the same viewpoint, the width of the groove 30 in the X direction of the topsheet 10 is preferably 0.5 to 7 mm, and preferably 1 to 3 mm. In the present embodiment, the flange portion 20 and the groove portion 30 are formed with the same width. However, the present invention is not limited to this. For example, the width of the flange portion 20 in the central region in the X direction of the topsheet 10 is set to the flange portion in the side region. The width may be wider than 20. Or it can be set as a desired form, such as making the width | variety of the collar part 20 and the groove part 30 random.

  The substantial thickness of the collar portion 20 is preferably 60 to 100%, particularly 70 to 100% of the apparent thickness. It is preferable that the substantial thickness itself of the collar portion 20 is 0.2 to 4 mm, particularly 0.3 to 3 mm, at the largest portion (top portion 21). When the collar portion 20 has such a thickness, the collar portion 20 is unlikely to fall down, the cushioning property of the topsheet 10 is improved, and the liquid absorbability (liquid passage property) is further improved. Further, when the substantial thickness of the collar portion 20 is thinner than the apparent thickness, specifically, when it is 90% or less, even when the cage sheet 1 is deformed into a curved shape when the cage sheet 1 is used, A gap generated between the top sheet 10 and the low density sheet 12 is prevented from becoming large. Moreover, the surface sheet 10 fits a wearer's skin flexibly. In addition, the substantial thickness of the groove part 30 is 0.1-1 mm.

  The brim portion 20 and the groove portion 30 have different substantial basis weights. In other words, the amount of fiber is different between the flange 20 and the groove 30. Specifically, the amount of fibers is substantially larger in the flange portion 20 than in the groove portion 30. Since the heel part 20 and the groove part 30 are formed in this way, the heel part 20 is not easily crushed against compression behavior in the thickness direction such as wearing pressure, and the compression pressure by the wearer's thigh is It is possible to flexibly deform the bending behavior in the width direction by the flexibility of the groove portion 30.

When the fiber weight of the collar part 20 and the groove part 30 is expressed by basis weight, the basis weight of the collar part 20 is preferably 30 to 150 g / m < ² >, particularly preferably 40 to 100 g / m < ² >. On the other hand, the basis weight of the groove part 30 (excluding the opening 31) is preferably 10 to 70 g / m ² , particularly preferably 15 to 50 g / m ² . The basis weight as a whole of the top sheet 10 (including the opening 31) is preferably 20 to 80 g / m ² , particularly preferably 30 to 80 g / m ² from the viewpoints of flexibility and nonwoven fabric strength. The basis weight of the collar part 20 is determined from the weight and area of the collar part 20 from which the groove part 30 is removed. When the width of the opening 31 and the width of the groove 30 are approximately the same, the boundary between the flange 20 and the groove 30 is determined by the position when a plurality of end portions in the width direction of the opening 31 are viewed in series. When the width of the groove portion 30 is wider than the width of the opening 31, the inflection point is set as a reference point (priority) based on the cross-sectional shape of the topsheet 10 to be measured, as in the case of apparent thickness measurement. The reference position is the tilt position of °. The top sheet 10 is cut along a straight line connecting the two upper and lower reference points to obtain the flange 20 and its weight is measured. The weight of the groove portion 30 is obtained from the difference between the weight of the top sheet 10 before cutting and the weight of the flange portion 20.

  As shown in FIG. 5, a large number of apertures 31 are formed in the groove 30. The apertures 31 are regularly formed at regular intervals along the direction in which the groove 30 extends. Therefore, the top sheet 10 has a row of holes formed of a large number of apertures 31 arranged at regular intervals along the Y direction (longitudinal direction of the cage sheet 1). It is in the state formed in multiple rows over the width direction of the cage sheet 1. The pitch of the arrangement of the apertures 31 in all aperture rows is the same. In two adjacent rows of apertures, the apertures 31 are located at the same position in the X direction of the topsheet 10. The opening 31 is arranged so that there is always a portion where the opening 31 is not formed when the entire sheet is viewed along the X direction of the sheet 10. Further, when viewed from the top sheet 10 as a whole, the apertures 31 are distributed and arranged so as to form a multi-row row in the X direction of the sheet 10 and a multi-row row also in the Y direction. By arranging the apertures 31 in this way, the apertures 31 can be efficiently formed by dividing the fibers as compared with the case where the apertures 31 are arranged in a staggered pattern, for example. Can do.

  The opening 31 is formed by separating the constituent fibers of the topsheet 10. In the vicinity of the end of the opening 31, a film-like structure resulting from the thermal deformation of the fiber is not formed. Due to this, the vicinity of the end portion of the opening 31 has low rigidity, and is excellent in flexibility and shape restoration property against deformation. Further, since the liquid passes through the structure, the liquid does not collect near the end of the opening 31. When viewed as the entire surface sheet, the constituent fibers are basically entangled between the fibers or the fibers are fused. Thereby, the form of the nonwoven fabric is maintained.

The opening 31 can take various shapes in a plan view of the topsheet 10. For example, a shape such as a circle, an oval, an ellipse, a triangle, a quadrangle, a hexagon, or a combination thereof can be given. What is necessary is just to determine suitably the shape and magnitude | size of the opening 31 according to the specific use of an absorbent article. The size of the opening 31 is preferably about 0.5 to ⁵ mm ² in terms of the projected area of the top sheet 10 in plan view from the viewpoint of liquid permeability and maintaining the strength of the top sheet 10. The size of the opening 31 is measured using an image analysis device. Specifically, a light source [Sunlight SL-230K2; manufactured by LPL Co., Ltd.], stand [copy stand CS-5; manufactured by LPL Co., Ltd.], lens [24 mm / F2.8D Nikkor lens], CCD camera [(HV-37; manufactured by Hitachi Electronics Co., Ltd.) F-mount connection with lens] and video board [Spectra 3200; manufactured by Canopus Co., Ltd.] take in. The captured image is binarized by the image analysis software NEW QUEBE (ver. 4.20) manufactured by NEXTUS. The average value of the individual areas obtained from the binarized image is taken as the size of the aperture.

  The opening 31 may have an end projecting toward the second surface 10b of the topsheet 10 to form a liquid introduction pipe including the projecting portion. As described above, since the end portion of the opening 31 has low rigidity, the cushioning property of the topsheet 10 is further enhanced by forming the protruding portion. Moreover, since the contact between the topsheet 10 and the low-density sheet 12 can be maintained regardless of the structure of the low-density sheet 12 located on the lower side of the topsheet 10 by forming the protruding portion, it is excreted from the wearer. The liquid is efficiently transferred from the top sheet 10 to the low density sheet 12.

  As one of the main features of the cage sheet 1 of the present embodiment, the contact angle of the constituent fibers of the surface sheet 10 (nonwoven fabric) having the grooved structure as described above is 60 to 85 °, and the non-surface sheet 10 The low-density sheet 12 with a low fiber density compared with the groove part 30 of the surface sheet 10 is arranged adjacent to the surface sheet 10 on the skin contact surface side. Here, the contact angle is an index indicating the level of hydrophilicity of the fiber, and is an angle between a water droplet on the fiber and the fiber surface, which is measured by a measurement method described later. The smaller the contact angle, the more the fiber. It can be judged that the hydrophilicity of is high. Usually, the contact angle of the constituent fibers of the surface sheet of this type of absorbent article is 50 ° or less, and it can be said that the fibers having a contact angle of 30 ° or less have high hydrophilicity. The fibers having a contact angle of 60 to 85 ° are fibers having low hydrophilicity, and the surface sheet 10 including such low hydrophilic fibers has low surface hydrophilicity.

  In general, when the surface sheet has high surface hydrophilicity, the liquid permeates into the inside from the contact portion with the surface sheet and moves inside the inside according to a capillary force gradient or the like. In addition, when the surface of the surface sheet is hydrophobic, the liquid hardly penetrates into the inside even if it comes into contact with the surface sheet, and moves between the surface sheet and the body or between the buttocks and the buttocks. . On the other hand, the surface sheet 10 according to the present embodiment having a low surface hydrophilicity is not so high in capillary force that the liquid in contact with the sheet 10 easily penetrates into the sheet 10. Since the water repellency is not so high that it is repelled from the surface and moves between the sheet 10 and the body, the liquid in contact with the sheet 10 is difficult to move in a plane. Furthermore, since the surface sheet 10 has a ridge groove structure, the space formed between the heel portions 20 and 20 is maintained between the wearer's body and the surface sheet 10 when wearing the cage sheet. Liquid diffusion due to decrease is also difficult to occur.

  For this reason, the cage sheet 1 includes the surface sheet 10 having such a groove structure and low surface hydrophilicity, and the low-density sheet 12 disposed directly below the surface sheet 10. Excellent absorbency for liquids with relatively high viscosity. That is, the liquid excreted from the body first adheres to the ridge groove structure (the ridge portion 20 and the groove portion 30) of the surface sheet 10, and as described above, the surface of the surface sheet 10 has low hydrophilicity. The liquid adhering to the top portion 21 of the flange portion 20 and the vicinity thereof is not absorbed (penetrated) at these portions, and moves to the groove portion 30 along the inclined surface of the flange portion 20. The movement of the liquid from the flange portion 20 to the groove portion 30 is mainly caused by poor adhesion between the top sheet 10 and the wearer's skin, and a gap is formed between the two. When the properties are good and there are almost no gaps, most of the excreted liquid adheres directly to the groove 30. The liquid adhering to the surface of the groove part 30 is pushed into the groove part 30 by the wearer's body pressure or the like applied in the thickness direction from the skin contact surface side of the sheet 1 when worn, and further disposed directly below the groove part 30. It is pushed into the low density sheet 12 and absorbed.

  When the liquid is pushed into the inside from the surface of the groove portion 30, the flange portion 20 and the groove portion 30 are formed so as to extend in the longitudinal direction of the lift sheet 1, so that the width direction of the liquid discharge sheet 1 is formed. Is prevented from spreading, thereby preventing side leakage. Moreover, the pushing of the liquid from the groove part 30 to the low density sheet 12 is smoothly performed because the fiber density of the low density sheet 12 is lower than that of the groove part 30. Such an absorption behavior of the liquid is easily manifested particularly when the viscosity of the liquid is medium (the viscosity at a liquid temperature of 25 ° C. is about 50 to 300 mPa · s). When the excreted liquid is highly viscous (the viscosity at a liquid temperature of 25 ° C. is approximately 300 mPa · s or more), the absorption behavior is substantially the same as the above-mentioned medium viscosity, but the highly viscous liquid Tends to remain on the surface of the top sheet 10 for a long time compared to the medium-viscous liquid. Therefore, after the high-viscosity liquid adheres to the surface of the groove 30, the liquid of the sheet 1 along the groove 30 It moves to the low density sheet 12 while diffusing in the longitudinal direction. Further, when the excreted liquid has a low viscosity and a low viscosity (viscosity at a liquid temperature of 25 ° C. is less than about 50 mPa · s), there is a strong tendency to be quickly absorbed at the site where the liquid has adhered, and the groove 30 Not only the buttocks 20 absorbs the liquid. Menstrual blood is usually a medium to high viscosity liquid. The viscosity is measured using a Brookfield viscometer.

  Such a phenomenon in the surface sheet 10 (nonwoven fabric) can be explained by using the following Lucas-Washburn formula used for analyzing the penetration of the liquid into the porous material. In the following formula, l is the penetration depth (diffusion distance), r is the capillary radius, γ is the surface tension of the liquid, θ is the contact angle, η is the viscosity, and t is time. According to the Lucas-Washburn equation, the liquid movement control factor in the nonwoven fabric (capillary structure) is r derived from the structure of the capillary structure, and θ indicating the contact state between the surface of the capillary structure and the liquid. Yes, the greater the capillary radius, the higher the surface wettability, the longer the diffusion distance. Here, in the low-viscosity liquid, the viscosity term (η), which is a denominator component, is small, and the capillary force factor due to the wettability term (cos θ) with the fiber surface (nonwoven fabric surface) and the size term (r) of the fiber space of the nonwoven fabric. The influence of (molecular component) is large. For this reason, the low-viscosity liquid diffuses in the capillary structure by capillary force. On the other hand, in the high viscosity liquid, the influence of the viscosity term (η) becomes strong and the influence of the wettability term (cos θ) which is one of the capillary force factors becomes small. Becomes smaller and diffusion in the capillary structure is less likely to occur. However, the influence of the size term (r) of the fiber space of the nonwoven fabric is large, and the liquid easily moves from the coarse fiber portion (groove portion 30) or the opening 31 having a large r. That is, the top sheet 10 according to the present embodiment is less likely to diffuse the highly viscous liquid in the interior thereof than the low viscous liquid, but the high viscous liquid passes through the coarse fiber portion such as the groove 30 and the opening 31. It can be said that the structure is easy to flow.

  The contact angle of the constituent fibers of the topsheet 10 (nonwoven fabric) is 60 to 85 °, preferably 70 to 80 °, as described above. If the contact angle is less than 60 °, the hydrophilicity becomes high, so that the fiber surface tends to get wet and may give an unpleasant sensation to the wearer. If the contact angle exceeds 85 °, the hydrophobicity becomes high. As a result, it is difficult for the liquid to move to the low-density sheet 12 adjacent to the top sheet 10, and leakage may occur. Here, the “contact angle of the constituent fibers of the top sheet (nonwoven fabric)” means the contact angle of the constituent fibers having the lowest contact angle among the plurality of constituent fibers of the top sheet. . Control of the fiber contact angle can be performed by selecting a surfactant or the like or a resin constituting the fiber. A surfactant or the like is usually used by kneading into a fiber or applying to a fiber surface. The contact angle is measured as follows. When the contact angle according to the following measurement method is 50 ° or less, it is hydrophilic, when it is greater than 60 ° and less than 90 °, it is low hydrophilic, and when it is 90 ° or more, it is hydrophobic.

(Measurement method of fiber contact angle)
The contact angle of the fiber is performed in the same manner as the contact angle measurement method described in Japanese Patent Application Laid-Open No. 2006-183168 relating to the previous application of the applicant. Specifically, a KEYENCE microscope VH-8000 was used with a medium-magnification zoom lens (with illumination ring) tilted at 90 °, and the condition was set to 500 times. As the measurement sample, a surface sheet (web) cut into a size of 70 mm in the longitudinal direction and 40 mm in the width direction was used. In the measurement sample, the longitudinal direction is the MD direction / width direction of the web is the CD direction, the measurement environment is 20 ° C./50% RH, and the measurement sample is the web with the measurement surface facing upward. It was set on the measurement stage so that it could be observed from the CD direction. In the measurement sample, the depth is preferably about 0.5 to 2 mm in order to minimize out-of-focus fibers. The reason for observing the web from the CD direction is that the fibers of the web are generally oriented in the MD direction, and the possibility that the fibers are arranged in the width direction of the measurement screen increases. By setting in this way, the lens is observed from a direction perpendicular to the fiber length direction.

  Next, water droplets are attached to the fiber surface with a spray bottle filled with ion exchange water (using a tool that makes the fog state as fine as possible) to the set measurement sample, and within 5 seconds (2 to the best possible). 3 seconds). The reason why it is necessary to capture an image in a short time after the attachment is to prevent the attached water droplet from evaporating due to the light emitted from the measurement unit of the microscope and to prevent the contact angle from being changed by the oil agent. The contact angles at five observation results with clear focal points at both ends or one end of the water droplet were measured, and the average value thereof was defined as “contact angle”. As shown in FIG. 11, the contact angle is measured by drawing a tangent line to the fiber of the water droplet and image analysis or a protractor. The contact angle can be measured by taking out the constituent fibers instead of the top sheet.

  From the viewpoint of reliably operating the liquid absorption system according to the present invention described above, it is preferable that the flange portion 20 has a higher fiber density than the groove portion 30. That is, it is preferable that the fiber density of each part in the cage sheet 1 decreases in the order of the collar part 20, the groove part 30, and the low density sheet 12 (among these, the fiber density of the collar part 20 is the highest). With such a configuration, viscous liquid such as menstrual blood is prevented from being absorbed by the heel part 20, and liquid permeability from the groove part 30 to the low density sheet 12 due to body pressure or the like is further improved. Excellent liquid absorbability can be obtained. If viscous liquid such as menstrual blood is absorbed at the apex 21 of the heel part 20 or in the vicinity thereof, it may cause stickiness.

The fiber density of the heel part 20 is preferably 0.02 to 0.1 g / cm ³ , more preferably 0.04 to 0.08 g / cm ³ . The fiber density of the groove part 30 is preferably 0.01 to 0.08 g / cm ³ , more preferably 0.02 to 0.07 g / cm ³ . The fiber density of the low density sheet 12 is preferably 0.005 to 0.08 g / cm ³ , more preferably 0.01 to 0.05 g / cm ³ . When the low-density sheet 12 has a multilayer structure in which two or more layers having different fiber densities are laminated in the thickness direction, the “fiber density of the low-density sheet” is a layer adjacent to the top sheet 10 (the highest density). It means the fiber density of the upper layer.

  Moreover, the ratio of the fiber density of the heel part 20 and the fiber density of the groove part 30 (the ridge part / groove part) is preferably 1.3 to 5, and more preferably 1.5 to 3. The ratio of the fiber density of the groove part 30 to the fiber density of the low density sheet 12 (groove part / low density sheet) is preferably 1.2 to 10, more preferably 1.5 to 5. The fiber density of each of the flange portion 20, the groove portion 30, and the low density sheet 12 is measured by the following method.

(Measurement method of fiber density of ridge and groove)
Obtaining each basis weight of the collar and groove obtained as a result of measuring the substantial basis weight of the collar and groove described above, and each area of the collar and groove obtained from the cross-sectional shape of the surface sheet, The fiber density is calculated. First, a description will be given of a method for measuring each area of the ridge and the groove from the cross-sectional shape of the surface sheet. An absorbent article in which the surface sheet to be measured is incorporated and no load is applied is used as a measurement sample. The cross section in the MD direction is observed using an image analysis device, and the cross-sectional areas of the flange portion and the groove portion of the surface sheet are measured. As the image analysis device, the same image analysis device as that used for the measurement of the size of the opening 31 described above can be used. The measurement target portion in the measurement of the cross-sectional area is a portion that does not have the opening portion (opening 31). Next, when holes are formed in the top sheet, the opening ratio of the top sheet is measured by an image analyzer or the like, and the weight and cross-sectional area of the top sheet are measured. Next, the sample is separated into a flange portion and a groove portion, the weight and cross-sectional area of the flange portion are measured, and the weight and cross-sectional area of the flange portion are subtracted from the weight and cross-sectional area of the original topsheet, respectively. Obtain the weight and cross-sectional area, respectively. The fiber density of each part is calculated from the weight and cross-sectional area of each of the collar part and the groove part thus obtained and the length of the top sheet. Moreover, the basic weight of each part is calculated from the weight of each part obtained and the total width of each part obtained from the cross-sectional image in the image analysis. In the groove portion, the actual basis weight and the actual fiber density are also calculated by subtracting the area corresponding to the opening.

(Measurement method of fiber density of low density sheet)
The low-density sheet is sandwiched between two acrylic plates (vertical 10 cm × width 10 cm × thickness 5 mm), and in this state, the cross-section of the low-density sheet is observed using an optical microscope. The average cross-sectional thickness (substantial thickness) of the density sheet is obtained, and the fiber density of the low density sheet is calculated from the substantial thickness and the basis weight of the low density sheet obtained in advance.

  However, when the top sheet 10 and the low density sheet 12 are embossed integrally, or when the low density sheet 12 is provided with irregularities by embossing or the like, the low density sheet 12 is visually identified. In the case where the possible high-density recesses are formed, when determining the fiber density of the low-density sheet, such recesses are ignored from the whole sheet, and the average cross-sectional thickness (apparent thickness) is determined. The apparent density of the low-density sheet is calculated from the apparent thickness and the basis weight of the low-density sheet obtained in advance, and the apparent density is regarded as the fiber density of the low-density sheet in which high-density recesses are formed. . Specifically, the apparent density is measured as follows. When the low density sheet is a flat sheet without irregularities, the substantial thickness and the apparent thickness are substantially equal.

(Measurement method of apparent density of low density sheet)
Do not crush the flat parts (or convex parts) of the low-density sheet in which the concave parts are formed across the concave parts with two acrylic plates (10 cm long x 10 cm wide x 2 mm thick). In this state, the cross section of the low-density sheet is observed using an optical microscope, and the average distance between the two acrylic plates is visually determined from the cross-sectional image to obtain the apparent thickness. The apparent density of the low density sheet is calculated from the basis weight of the low density sheet obtained in advance.

When the opening 31 is formed in the groove portion 30 as in the present embodiment, the excreted high-viscosity liquid is first guided to the opening 31 by an external force such as body pressure, and then moves to the low-density sheet 12. . At this time, if the low-density sheet 12 has a lower density than the flange portion 20 of the top sheet 10, the liquid easily moves to the low-density sheet 12, and the low-density sheet 12 is more than the substantial fiber density of the grooves 30 of the top sheet 10. If the density is low, it is easy to prevent the topsheet 10 from getting wet. The substantial fiber density is calculated excluding the opening 31 of the groove portion 30 of the topsheet 10. The real fiber density of the groove part 30 is preferably 0.02 to 0.12 g / cm ³ , more preferably 0.03 to 0.10 g / cm ³ , and the real fiber density of the groove part 30 and the fibers of the low density sheet 12 The difference from the density (fiber density difference) is preferably 0.02 or more, particularly preferably 0.03 or more. In addition, instead of forming the opening 31 in the groove portion 30, a portion having a relatively high fiber density and a portion having a low fiber density may be formed in the groove portion 30, and the fiber density is thus formed in the groove portion 30. In this case, substantially the same effect as the case where the opening 31 is formed is produced.

  In addition, from the viewpoint of reliably operating the liquid absorption system according to the present invention described above, the collar portion 20 has a top portion 21 in the cross section in the width direction X of the cage sheet 1 as shown in FIG. It is preferable that the width is increased toward the lower portion from the top portion 21. More specifically, the cross-sectional shape of the collar portion 20 is preferably a triangular shape, a mountain shape, a semicircular shape, or the like. Since the flange portion 20 has such a cross-sectional shape, the viscous liquid attached to the top portion 21 of the flange portion 20 and the vicinity thereof moves to the groove portion 30 along the inclined surface of the flange portion 20. Therefore, the above-described liquid absorption system according to the present invention works more reliably. Moreover, the inconvenience that a liquid adheres and remains on the surface of the surface sheet 10 by applying pressure such as body pressure can be suppressed.

  On the other hand, as shown in FIG. 4, when the top portion 21 of the flange portion 20 is flat and is not curved convexly upward as shown in FIG. 3, the liquid is applied to the flat top portion 21. It is difficult for the liquid to move to the groove portion 30 as described above with the adhesion. Therefore, the cross-sectional shape as shown in FIG. 4, specifically, the trapezoidal shape, the convex shape, the square shape, the rectangular shape, etc. has a cross-sectional shape as shown in FIG. It is inferior in liquid absorbency as compared with the liquid and tends to remain on the surface sheet.

  Although the topsheet 10 shown in FIGS. 1 and 2 has a single-layer structure, the topsheet 10 may have a multilayer structure of two or more layers instead. However, when the topsheet 10 has a multilayer structure, there is a possibility that liquid absorption may be inhibited at the interface of each layer. For this reason, the surface sheet 10 preferably has a single layer structure as shown in FIGS.

In the above-described liquid absorption system according to the present invention, the low-density sheet 12 serves as a liquid holding layer, and a space (a gap between fibers) in which a certain amount or more of liquid can be stored. Is preferably formed. From such a viewpoint, the low-density sheet 12 has a basis weight of 20 to 100 g / m ² , particularly 30 to 80 g / m ² , and fiber density (a concave portion that can be visually identified is formed on the surface of the low-density sheet. apparent density if any) is 0.005~0.06g / m ^3, it is particularly preferably 0.007~0.04g / m ^3. Further, the thickness of the low density sheet 12 under no load is preferably 0.2 to 3.0 mm, more preferably 0.5 to 1.mm, from the viewpoint of achieving both a soft feeling due to cushioning and a comfortable wearing feeling. 5 mm. Further, the low density sheet 12 is preferably a flat sheet without unevenness, that is, a sheet in which the fiber density and the apparent density show substantially the same numerical values.

  Further, the constituent fibers of the low-density sheet 12 are oriented in the thickness direction (Z-axis direction) of the sheet, so that the liquid that has passed through the surface sheet 10 is quickly taken in, and the space between the surface sheet 10 and the low-density sheet 12 is This is preferable in that it is easy to suppress liquid diffusion at the inside and liquid diffusion inside the low density sheet 12. From such a viewpoint, the orientation angle of the constituent fibers of the low density sheet 12 is preferably 50 to 130 °, more preferably 60 to 120 °, and still more preferably 70 to 110 °. The orientation angle of the constituent fibers is measured by the following method. When the orientation angle of the sheet according to the following measuring method is in the range of 50 to 130 °, it can be said that the constituent fibers of the sheet are oriented in the thickness direction of the sheet. In addition, when the measurement result of an orientation angle is obtained in the range of 180-360 degrees, it converts into 0-180 degrees and calculates by subtracting 180 degrees from the obtained orientation angle specifically.

(Measurement method of orientation angle of constituent fibers)
When measuring the orientation angle of the constituent fibers, cross-sectional observation with a microscope is necessary, and it is necessary to capture and measure the shape in which the fibers extend, and it is necessary to evaluate the orientation of the ridge and groove structure in the topsheet Therefore, the cross section inclined by 45 degrees from the MD direction was observed in the surface sheet, and the cross section in the MD direction was observed from the CD direction side in the low-density sheet in the same manner as the contact angle measurement method described above. The depth of the measurement sample is 2 mm or less in the case of a KEYENCE microscope VH-8000 with a medium magnification zoom lens, but generally 5 mm or less when an electron microscope (SEM) having a deep focal depth is used. In the present invention, JCM-5100 manufactured by JEOL Ltd. was used. A cross-sectional photograph taken by cross-sectional observation with a microscope is converted into image processing software [Image-PRO PLUS Ver., Manufactured by Nippon Roper Media Cybernetics Co., Ltd.]. 6.2 (Japanese version)], binarize the fiber, perform discrete two-dimensional Fourier transform, and perform XY graphing to obtain a power spectrum. This power spectrum becomes an ellipse when the fiber is oriented, and becomes an ellipse with a large flatness when the fiber is strong, and becomes closer to a perfect circle as the orientation of the fiber is randomized. Here, the orientation angle of the fiber is the inclination of the major axis of the ellipse on the X axis, and the ratio of the major axis to the minor axis is the orientation strength. The method described in “Abstracts of the 26th Annual Meeting of the Cultural Properties Preservation and Restoration Society, 44-45 (2004)” may be performed after the above-described XY graphing by Fourier transform, or the method may be The orientation angle and orientation angle strength may be obtained from image processing. In addition, the orientation angle and orientation angle strength of the constituent fibers in the surface sheet 10 are such that the surface sheet 10 has an uneven shape (groove groove structure), so that the groove portion 30 extends from the top portion 21 of the flange portion 20 in the width direction. Measurement is performed at a portion that is divided into 3 to 4 and does not include the flange 20 and the groove 30. The orientation angle strength is a value indicating the regularity of fiber orientation. If the numerical value exceeds 1, the fiber orientation is considered to be high.

  As a method for adjusting the orientation angle of the constituent fibers of the sheet within the above range, that is, orienting the constituent fibers of the sheet in the thickness direction, for example, production of a low-density sheet by an airlaid method is exemplified. As is well known, the airlaid method is a method for manufacturing a nonwoven fabric including a step of forming a web by dropping and depositing fibers placed on an airflow onto a net. As another method, a sheet in which constituent fibers are substantially oriented in a direction orthogonal to the thickness direction of the sheet (sheet surface direction) and the fiber orientation of the sheet is changed by mechanical means. Is mentioned. The sheet in which the constituent fibers are substantially oriented in the surface direction of the sheet is, for example, a fiber sheet forming method in which fiber entanglement is performed like a needle punch method after forming a web by a card method without any special device. It is obtained by a method of changing the fiber orientation of the fiber sheet having a small fiber orientation by mechanical means. The change of the fiber orientation by such mechanical means can be performed as follows, for example. That is, slits (cuts) extending in one direction and not penetrating in the thickness direction of the sheet are formed at a predetermined interval in a direction orthogonal to the one direction in the sheet in which the constituent fibers are substantially oriented in the surface direction of the sheet. And a plurality of sheets (fiber assemblies) positioned between adjacent slits are rotated by approximately 90 degrees with the one direction (the direction in which the slits extend) as the rotation axis direction. The orientation angle of the constituent fibers can be adjusted to the above range. Moreover, after cutting | disconnecting in a slit position, it can also obtain by sticking a different sheet material with an adhesive agent etc. and rotating 90 degrees similarly.

  The low-density sheet 12 shown in FIGS. 1 and 2 has a single-layer structure, but the low-density sheet 12 may have a multilayer structure of two or more layers instead. When the low-density sheet 12 has a two-layer structure including, for example, an upper layer adjacent to the top sheet 10 and a lower layer laminated on the non-skin contact surface side of the upper layer, the lower layer is lower in layer than the upper layer. It is preferable to increase the fiber density. That is, the low-density sheet 12 having a preferable multilayer structure is formed by sequentially laminating an upper layer and a lower layer from the surface sheet 10 side, and the upper layer has a lower fiber density than the lower layer. According to such a low-density sheet having a two-layer structure, the collection ability and the suppression of diffusion by separating the water in the viscous material after drawing the highly viscous liquid is improved. The fiber density is measured according to the measurement method described above. The fiber density can be controlled by the fiber thickness, fiber resin material, or the like. The basis weight ratio (upper layer / lower layer) of the upper layer and the lower layer is preferably 1 to 5, and more preferably 1.5 to 3.

  As described above, in the present embodiment, the seal portion 15 is formed by joining the top sheet 10 and the back sheet 11 to each other by heat treatment over the entire outer peripheral edge of the cage sheet 1. As described above, since the topsheet 10 has a groove structure composed of groove grooves extending in the longitudinal direction, when the groove structure is heat-treated to form a uniform thickness seal portion, the vicinity of the seal portion There is a possibility that a large step is generated between the groove structure located in the groove and the seal portion, which may lead to discomfort during wearing. In particular, as shown in FIG. 1, when a constricted portion is present in the central portion in the longitudinal direction of the cage sheet, such a problem is likely to occur in the seal portion located in the constricted portion. Therefore, from the viewpoint of reducing the level difference due to the adoption of such a gutter groove structure and obtaining a better wearing feeling, the seal portion 15, particularly the longitudinal center portion of the vaginal discharge sheet 1 or the excretion portion of the wearer is provided. It is preferable that the seal part 15 located in the constriction part which exists in the opposite excretion part opposing part is decreasing in thickness as it goes to the outer periphery from the inner periphery. The seal part 15 having such a thickness distribution is a part that becomes an outer peripheral edge from a part that becomes the inner peripheral edge of the seal part 15 in both sheets 10 and 11 when the top sheet 10 and the back sheet 11 are heat-treated as usual. The pressure is obtained in multiple stages toward the surface, and the pressure in each stage is increased as it goes toward the outer peripheral portion.

  From the above viewpoint, it is preferable that the seal portion 15 is formed in a linear shape in a direction generally along the appearance shape of the cage sheet 1. Further, from the viewpoint of stabilizing the sealing portion 15 while improving the flexibility of the cage sheet 1, the sealing portion 15 includes a plurality of sealing portions that do not intersect with each other in a plan view (top view) as shown in FIG. From the viewpoint of making it difficult to leak, the line (compressed portion of the surface sheet) constituting the seal portion is preferably formed on the surface sheet in plan view. It is preferable to have a part which overlaps with a collar part. Moreover, it is preferable from the viewpoint of the strength of the seal portion 15 that the seal portion 15 includes an adhesive.

  Next, constituent materials and the like of the cage sheet 1 according to the present embodiment will be described. As the back sheet 11, those used in this type of conventional absorbent article can be used without any particular limitation. As the back sheet 11, a liquid-impermeable or water-repellent material, for example, a film made of a thermoplastic resin, or a laminate of a nonwoven fabric can be used. A spunbond-meltblown-spunbond (SMS) nonwoven fabric or a spunbond-meltblown-meltblown-spunbond (SMMS) nonwoven fabric can also be used. The back sheet 11 may have moisture permeability. Examples of the back sheet having moisture permeability include a porous film obtained by extruding a resin composition containing a thermoplastic resin and fine particles incompatible with the thermoplastic resin into a film shape and uniaxially or biaxially stretching, and the above-described SMS nonwoven fabric. It is done.

  As a constituent fiber of the surface sheet 10 (nonwoven fabric), fibers conventionally used in the technical field such as natural fibers, semi-natural fibers, and synthetic fibers can be used without particular limitation. From the viewpoint of imparting flexibility to the topsheet 10 without causing clogging between fibers, it is preferable to use synthetic fibers. The blending amount of the synthetic fiber is preferably 50% by weight or more, more preferably 70% by weight or more of the entire surface sheet. Of course, you may comprise the surface sheet 10 from 100% of synthetic fiber. When the topsheet 10 is made of 100% synthetic fiber, the grooving structure is not easily crushed even under the condition where the body pressure of the wearer is applied, so that the air permeability along the groove 30 is good.

  As a synthetic fiber used for the surface sheet 10, the core-sheath structure fiber and the side-by-side type fiber which are self-bonding fibers are mentioned, for example. In addition, single fibers and composite fibers such as polyethylene, polypropylene, and polyester can be used. From the viewpoint of the groove-shaped structure and the formability of the aperture shape, it is preferable to use a core-sheath structure fiber having polyethylene as a sheath component and a side-by-side fiber having a polyethylene portion. The (average) fineness of the fiber is preferably in the range of 1 to 6 dtex.

  It is preferable to use crimped fibers as the synthetic fibers used for the topsheet 10 because the cushioning properties of the topsheet 10 are further improved. As the crimped fiber, either a two-dimensionally crimped fiber or a coiled three-dimensionally crimped fiber can be used. In particular, it is preferable that the surface sheet 10 includes fibers that are three-dimensionally crimped in a coil shape by application of heat. Such a fiber can be included in the topsheet 10 by using latent crimped fibers as a raw material. The latent crimped fiber is composed of, for example, an eccentric core-sheath type composite fiber or a side-by-side type composite fiber containing two types of thermoplastic resins having different shrinkage rates as components. Examples thereof include those described in JP-A-9-296325 and Japanese Patent No. 2759331.

  As the synthetic fiber used for the topsheet 10, it is preferable to use a fiber that is elongated by application of heat because the cushioning property of the topsheet 10 is further enhanced. This is because clogging between fibers due to heat applied during the manufacture of the topsheet 10 is prevented. As such a fiber, for example, WO2007 / 66599 according to the previous application of the present applicant can be mentioned.

  When any of the above-described crimped fibers and heat-extensible fibers is used, it is preferable that those fibers are mixed in the surface sheet 10 in a total amount of 30 to 70% by weight.

  As the low density sheet 12, for example, an air-through nonwoven fabric, a needle punched nonwoven fabric, a spunbonded nonwoven fabric or the like is used. Among these, in order to use as an upper layer (a layer adjacent to the topsheet 10) in the low-density sheet having a single-layer structure or the low-density sheet having a two-layer structure, an air-through nonwoven fabric is preferable from the viewpoint of cushioning properties and bulkiness.

  As the constituent fibers of the low density sheet 12, natural fibers, semi-natural fibers, various synthetic fibers, and the like can be used. Among these, a synthetic fiber having a heat-fusible component and a component having a higher melting point than the heat-fusible component is preferable from the viewpoint of easy formation of a low-density structure due to bulkiness, nonwoven fabric strength, and good cushioning properties. .

  The cage sheet 1 of the present embodiment is used by being fixed to the inner surface of the undergarment through an adhesive portion (not shown) disposed on the surface of the back sheet 11. The cage sheet 1 of the present embodiment is excellent in liquid absorbency due to the action of the liquid absorption system described above, not only for low viscosity liquids such as urine, but also for body fluids with relatively high viscosity such as menstrual blood, Since it can be absorbed and held in the inside of the sheet 1 without leaving it on the top sheet, stickiness hardly occurs and the feeling of use such as wearing feeling is good.

  Next, the suitable manufacturing method of the cage sheet 1 of this embodiment is demonstrated. First, the manufacturing method of the surface sheet 10 shown in FIG. 5 is demonstrated. The topsheet 10 is manufactured by the fluid entanglement method using the apparatus shown in FIG. In the manufacturing method using this apparatus, (a) a fiber assembly is supplied, and the fiber assembly is formed on a fluid-permeable support for forming a wavy structure in a direction orthogonal to the supply direction of the fiber assembly. (B) a step of spraying a fluid to the fiber assembly located on the support to separate the constituent fibers so as to form a slotted groove structure and an opening; and (c) subsequently on the support. There is a step of spraying a fluid again on the fiber assembly positioned to make the fiber assembly in which the groove structure and the opening are formed into a nonwoven fabric.

  The apparatus 40 shown in FIG. 8 includes a fluid permeable support 50, a first injection nozzle 51, and a second injection nozzle 52. As shown in FIG. 8, the fluid-permeable support 50 is a roll, and its peripheral surface is made of a fluid-permeable material such as a mesh. On the peripheral surface of the support 50, convex portions and concave portions extending along the rotation direction of the roll are alternately formed in the axial direction of the roll. Thereby, a wave-like structure can be formed in the fiber assembly 53 which is a raw material of the topsheet 10 in a direction orthogonal to the supply direction. Projections 54 formed intermittently along the rotation direction of the roll are located on the tops of the protrusions. The protrusions 54 are arranged at regular intervals along the rotation direction of the roll. And when it sees along the axial direction of a roll, the projection part 54 is arrange | positioned so that it may be located on a straight line.

  The 1st injection nozzle 51 and the 2nd injection nozzle 52 are arrange | positioned so that the surrounding surface of the support body 50 may be opposed. Each of the nozzles 51 and 52 has a structure capable of ejecting fluid over the entire width of the support 50. In the nozzles 51 and 52, the first injection nozzle 51 is located on the upstream side and the second injection nozzle 52 is located on the downstream side in the supply direction of the fiber assembly 53 that is the raw material of the topsheet 10.

  In the step (a), the fiber assembly 53 is supplied to the fluid permeable support 50 rotating in the direction of the arrow in FIG. 8 and conveyed while being held by the peripheral surface of the support 50. Is done. Next, in the step (b), the fluid ejected from the first ejection nozzle 51 is sprayed onto the fiber assembly 53 on the peripheral surface of the support 50. Due to the pressure of this fluid spraying, the fiber assembly 53 is displaced from the constituent fibers at the position of the convex portion 55 formed on the peripheral surface of the support 50 as shown in FIGS. 10 (a) and 10 (b). Dividing occurs. By this separation, the constituent fibers move into the concave portions 56 located between the convex portions 55. That is, fiber distribution occurs.

  Further, in the case where the protrusion 54 is formed on the top of the convex portion 55, as shown in FIG. 10C, the separation of the constituent fibers is further promoted, and the fiber assembly located on the protrusion 55 A hole is formed at 54. This hole becomes the opening 31 in the topsheet 10.

  As the fiber assembly, there can be used those in which fibers such as card web are not bonded or entangled, or the degree thereof is low, or those in which fibers such as nonwoven fabric are bonded or entangled. In particular, as a non-woven fabric, a non-woven fabric containing fibers having a fiber length of 30 mm or less and having no binder component itself, specifically, a dry type in which fibers between pulp fibers are fixed by a binder (adhesive component). It is preferable to use a pulp sheet.

  As the fluid used in this step, a liquid such as water and a gas such as air can be used. The type of fluid is selected according to the fiber assembly guided on the support 50. For example, when using a fiber assembly that is not bonded or entangled like a card web, it is preferable to use an air flow or a water vapor flow (steam jet). In the case of using a fiber assembly having bonds at fiber intersections, such as an air-through nonwoven fabric, it is preferable to use a water stream or a steam stream (steam jet). In the latter case, the grooving structure and the opening can be formed by the movement of the fiber while partly peeling the bond at the fiber intersection and keeping the degree of fiber entanglement low. In addition, it is possible to prevent clogging between the fibers. As described above, this step mainly forms the groove structure and the opening by the movement of the fiber, and the degree of the entanglement of the fiber is kept low.

  The above-mentioned water flow means a complete liquid flow such as water. A water vapor stream (steam jet) refers to a fluid stream of water that is not in a liquid state. When a liquid water flow or a water vapor flow (steam jet) is used, the fiber entanglement progresses as the fiber is located in the vicinity of the protrusion 55, and the fiber density of the portion tends to increase. In particular, when a nonwoven fabric is used as the fiber assembly (that is, re-nonwoven fabric), since the fiber 55 is hardly entangled with the convex portion 55, the cushion feeling inherent to the nonwoven fabric is maintained. On the other hand, the fibers located in the vicinity of the concave portion 56 and the protruding portion 55 are entangled, and the capillary gradient (density gradient) is relatively large with respect to the fibers located in the convex portion 55.

  When the groove structure and the opening are formed by spraying the fluid from the first injection nozzle 51 which is the step (b), then fiber entanglement is performed by spraying the fluid from the second injection nozzle 52 which is the step (c). And the fiber assembly is made into a nonwoven fabric (when a nonwoven fabric is used as the fiber assembly, it is made into a non-woven fabric). As the fluid used in this case, it is preferable to use a liquid water stream or a water vapor stream. By using these fluids, fiber entanglement can be performed efficiently. The above-mentioned re-non-woven fabric refers to the re-melting of the fiber from which the cut or fused portion of the fiber was peeled off in the previous step of forming the groove structure and the opening when the non-woven fabric was used as the fiber assembly. It means that the form as a nonwoven fabric is maintained by wearing or entanglement again.

  When the fluid sprayed to the fiber assembly 53 in the step (b) and the step (c) is concentrated on the convex portion 55 of the support body 50, the fluid pressure of the convex portion 55 is increased compared to the concave portion 56 of the support body 50. Therefore, it is preferable because the openability is improved. Moreover, it is preferable at the point which can make the fiber density of the edge part vicinity of a hole higher.

  When a steam flow is used as the fluid in the step (c), the steam flow from the second injection nozzle 52 is set to a relatively low temperature of 100 to 150 ° C. (a temperature lower than the fiber fusion temperature on the web). Thus, only fiber entanglement is performed. Since the water vapor stream has lower energy (injection pressure) than the liquid water stream (the dispersion of the fluid stream is large), it is preferable to use it when spraying the web rather than using a nonwoven fabric as the fiber assembly. This is because the movement of the fiber is easier in the web than in the non-woven fabric. However, even when a nonwoven fabric is used as the fiber assembly, the jet pressure that results in a weak fiber entangled state that does not recover the shape of the groove structure and the opening formed by the step (b) is caused by the steam flow. Can be given. Furthermore, in the case where the temperature of the water vapor flow is about 160 to 200 ° C., which is higher than the fiber fusion temperature on the web, even if the temperature is 20 ° C. or more higher than the fiber fusion temperature, the fibers in the fiber assembly The amount of heat applied is not so great that the resin constituting the fiber melts and flows strongly, and the flow of the resin does not always occur at the intersection of all fibers, so that the entire fiber assembly is not melted. It does not solidify. Therefore, even when the jet pressure of the water vapor flow is high and the fibers are in close proximity to each other, it is possible to perform fusion at the fiber intersection without causing fiber clogging.

  Since this fusion is performed by the water vapor flow blown from the second injection nozzle 52, a stronger pressure is applied to the fiber assembly in a short time compared to the air-through method, which is a known nonwoven fabric manufacturing technique. Therefore, the pressure is removed before the fusion at the fiber intersection is stabilized, that is, before the outflow of the fiber sheath component resin that spreads on the surface of each fiber and becomes a strong fusion point is fixed. As a result, the fibers are separated to form a bridge structure. Such a bridging structure is estimated to be formed by melting and solidifying the sheath component resin of one of the two fibers. This is because, although this fusion process is in a state of causing fiber fusion, the application of heat is completed in a relatively short time, so the resins constituting the fibers that cause fiber fusion fuse together to form a resin. This is because it is considered that there is an interface between the resins constituting each fiber that causes fiber fusion rather than a state in which the interface between them disappears. In addition, if elongation occurs near the interface between the resin, which is the fusion part that has caused fiber fusion, the interface is pulled, the fusion part is reduced, and the resins are separated at the interface. Because it is. For this reason, the bridging structure has a portion where the area of the joint portion is large but the resin is stretched and thinned. As a result, the obtained surface sheet 10 is improved in the degree of freedom of its constituent fibers, and the flexibility and cushioning properties are improved. On the other hand, since it is manufactured under a pressure stronger than that of the air-through method, it is easier to make a multi-intersection of more than two fibers. With such a structure, the strength of the topsheet 10 is improved.

  When a liquid water stream is used in step (b) and / or step (c), the surfactant used for imparting hydrophilicity may flow down from the fiber surface, so that the surface activity into the fiber may occur. It is preferable to use a kneaded agent or a natural / semi-natural hydrophilic fiber. Or it is preferable to apply | coat surfactant in a post process. On the other hand, when the water vapor flow is used, there is an advantage that the surfactant on the surface of the fiber is less likely to flow down and the surfactant can be easily collected at a part where the fiber density is high. As a result, when the water vapor flow is used, the fiber density of the portions located in the concave portions 56 and the projections 54 of the support 50 in the fiber assembly 53 is increased, so that the hydrophilicity of these portions can be inevitably increased. As an application example of this effect, there is a technique in which two or more kinds of surfactants to be applied to the fiber surface or surfactants kneaded into the fiber are used, and the water resistance of the surfactant is made different. This method is advantageous because the hydrophilic gradient can be designed more easily.

  In order to further control the fiber density of the obtained surface sheet 10, it is also preferable to subject the nonwoven fabric after the step (c) to a hot air treatment step. The hot air treatment has an effect of promoting the formation of a nonwoven fabric (bonding the fibers of the fiber assembly) and / or eliminating clogging between the fibers. In other words, in the step (c), from the viewpoint of preventing clogging, the fluid spraying condition may be weakened, and the hot air treatment step may be applied to compensate for the lack of fiber entanglement or fiber fusion resulting therefrom. preferable. Moreover, it is preferable to attach to the hot-air treatment process in order to recover the bulk of the nonwoven fabric in which clogging has occurred in the process (c) or to develop fiber deformation (crimping or stretching). In particular, when the steam flow is used in the step (c), the second spray nozzle 52 is used, so that the heat application step is completed in a shorter time than the air-through method. Therefore, from the viewpoint of stabilizing the heat-sealed state, it is desirable to perform a hot air treatment process at about 80 to 120 ° C. as a subsequent process of the process (c). Or it is preferable to perform the stabilization process which does not raise | generate a rapid temperature fall as a post process of the process of (c). The hot air treatment may be performed in one stage, or the hot air treatment for promoting the formation of a nonwoven fabric and the hot air treatment for restoring the bulk of the nonwoven fabric may be performed in a plurality of stages.

  When only the web is used as the fiber assembly in this production method, it is preferable to use an air flow or a water vapor flow in the step (b) and use a water vapor flow in the step (c). This is because clogging between fibers can be prevented, a flexible structure can be formed by forming a nonwoven fabric by fusing the fiber intersections, and the fiber density at the periphery of the apertures 31 can be easily increased. Further, when an air flow is used in the step (b), it becomes easy to form a liquid introduction pipe in the opening 31, and parts other than the opening 31 are also likely to have the shape of FIG. Improves. On the other hand, when the water vapor flow is used in the step (b), the scattering of the fibers is suppressed and the fluid pressure can be easily made higher than the air flow. It becomes easy to improve flexibility such as cushioning. Even if the water vapor flow is used in the step (b), it is possible to achieve both the liquid guide tube structure and the cross-sectional shape of FIG. 6 by adjusting the fluid pressure in the opening 31.

  In this production method, when a water stream is used in the steps (b) and (c), it is preferable to use a nonwoven fabric having a fusion point at the fiber intersection. The reason for this is that fiber clogging can be prevented by the movement of fibers (formation of a density-enhanced portion) by the separation portion at the fiber intersection and the remaining fusion point. In this case, in the step (b), the nonwoven fabric is adapted to the shape of the support by applying a water flow so as to be substantially uniform over the entire nonwoven fabric, and in the step (c), the grooves 30 including the openings 31 are It is preferable from the viewpoint of facilitating re-entanglement by facilitating peeling of the fusion point and making the water pressure in the step (c) higher than (b) by facilitating entanglement by blowing a stronger water flow than the part 20. Further, when a method of supplying a fiber assembly 53 by using a laminate of a web and a nonwoven fabric as a fiber assembly 53 or by laminating both webs and a nonwoven fabric while supplying the fiber assembly 53, (B) and ( Integration of the two can be promoted in step c). The nonwoven fabric produced in this way has a structure (integrated structure) that can easily guide the liquid from the top portion 21 of the collar portion 20 to the end portion of the opening 31. In this case, it is preferable to use a nonwoven fabric from the viewpoint of preventing fiber clogging in the web and the nonwoven fabric from which water is directly sprayed. Thus, when a water flow is used in the steps (b) and (c), it becomes easy to obtain a cross-sectional shape as shown in FIG.

  When a non-woven fabric is used as the fiber assembly 53 and the non-woven fabric is separately guided onto the support before the step (b), the flexibility and cushioning properties of the resulting non-woven fabric can be improved. In addition, when using a nonwoven fabric as the fiber assembly 53, if the fibers are strongly bonded or entangled in the nonwoven fabric, fiber movement in the step (b) may be difficult to occur, so before the step (b), It is also preferable to subject the non-woven fabric to a portion to be positioned in the concave portion 56 of the support 50.

  The sheet thus obtained is placed on a separately manufactured low-density sheet 12, and the top sheet and the like are processed according to a conventional method together with the back sheet 11 to obtain the target cage sheet 1. .

As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, an absorber may be interposed between the low density sheet 12 and the back sheet 11. As the absorber, paper; a pulp layer including wood fluff pulp; a polymer sheet (for example, an absorbent polymer disposed between fiber sheets such as two sheets of paper) and the like can be used. The pulp layer may contain an absorptive polymer usually used in the technical field, and the whole pulp layer may be covered with tissue paper. The basis weight of the absorber is preferably 50 to 300 g / m ² , and the thickness under no load is preferably 0.5 to 1.0 mm.

  Further, a leak-proof cover sheet may be disposed on the top sheet 10 in the left and right side regions of the cage sheet 1. Further, a pair of wings extending outward in the width direction may be provided on both side edges in the longitudinal direction of the napkin 1. Moreover, in the said embodiment, although the sheet | seat (panty liner) was mentioned as one of the application examples of the absorbent article of this invention, For example, it can apply also to absorbent articles, such as a sanitary napkin and an incontinence pad. Each structure mentioned above can be combined suitably.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to such examples.

[Example 1]
Using a 2.2 dtex × 38 mm core-sheath structure fiber of sheath component polyethylene / core component polyester, a nonwoven fabric is formed by a steam flow according to the above-described method for producing the top sheet, and the groove structure and opening as shown in FIGS. The surface sheet of Example 1 having 40 g / m ² having holes was obtained. The obtained top sheet was 3 mm in width of the ridge part, 2 mm in width of the groove part, and 1.2 mm in thickness (apparent thickness at the top part of the ridge part). For the thickness, the top sheet was heated to 60 ° C. It was adjusted to 0.7 mm by inserting between press rolls and compressing. The groove part of the surface sheet had an elliptical opening having substantially the same width as the groove part, and the opening ratio after compression was 8%. In addition, a low-density sheet (nonwoven fabric) having a basis weight of 40 g / m ² and having no irregularities on the surface is obtained by using a 2.2 dtex × 51 mm core-sheath structure fiber of sheath component polyethylene / core component polyester to produce a nonwoven fabric by the air-through method. It was. Using the thus obtained top sheet, low density sheet, and back sheet (polyethylene resin film having a basis weight of 22 g / m ² ), a sheet having a cross-sectional shape as shown in FIG. The sample of Example 1 was used. The sheets in the sample are bonded by a hot melt adhesive spiral method (adhesive application amount 5 g / m ² ). The outer shape of the obtained sample was a violin type having a length of 150 mm in the longitudinal direction and a length of 60 mm in the width direction. The thickness of the sample was about 1.2 mm.

[Example 2]
In Example 1, a non-woven fabric having a basis weight of 80 g / m ² was used as the low-density sheet in the same manner as in Example 1 to produce a sheet, which was used as the sample of Example 2. The thickness of the sample of Example 2 was about 4.7 mm.

Example 3
In Example 1, a plurality of slits (cuts) extending in one direction and not penetrating in the thickness direction of the sheet were formed in the obtained low density sheet at a pitch of 2 mm in a direction perpendicular to the one direction. A sheet was prepared in the same manner as in Example 1 except that the cut surface of the slit was fixed to the back sheet, and this was used as the sample of Example 3. The orientation angle of the constituent fibers of the low density sheet in Example 3 is different from that in Example 1 due to the formation of the slits and the fixation with the back sheet. The thickness of the sample of Example 3 was about 2.7 mm.

Example 4
In Example 1, a sheet was prepared in the same manner as in Example 1 except that the surface sheet was not compressed and used with a thickness of 1.2 mm, and this was used as a sample of Example 4. The thickness of the sample of Example 4 was about 1.7 mm. Moreover, the groove part of the surface sheet had an elliptical opening having substantially the same width as the groove part, and the opening ratio was 10%.

[Comparative Example 1]
In Example 1, a sheet was prepared in the same manner as in Example 1 except that a nonwoven fabric having a basis weight of 30 g / m ² having no groove structure and no openings was used as the top sheet, and this was used as a comparative example. One sample was used. The nonwoven fabric (surface sheet) was produced by making a nonwoven fabric by an air-through method using 2.2 dtex × 51 mm core-sheath structure fiber of sheath component polyethylene / core component polyester. The thickness of the sample of Comparative Example 1 was about 1 mm.

[Comparative Example 2]
In Example 1, except that a low-density sheet was not used, a sheet was produced in the same manner as in Example 1, and this was used as a sample of Comparative Example 2. The thickness of the sample of Comparative Example 2 was about 0.7 mm.

[Comparative Example 3]
A commercially available cage sheet (trade name “Laurier F Panty Liner” manufactured by Kao Corporation) was used as a sample of Comparative Example 3. The surface sheet in this sample has a two-layer structure of an upper layer and a lower layer. In Table 1 below, each characteristic value when the lower layer is regarded as a low-density sheet is described. The thickness of the sample of Comparative Example 3 was about 1.2 mm.

[Comparative Example 4]
In Example 1, a sheet was prepared in the same manner as in Example 1 except that the following were used as the top sheet and the low density sheet, and this was used as a sample of Comparative Example 4. The thickness of the sample of Comparative Example 4 was about 1.4 mm. Using a 2.2 dtex × 38 mm core-sheath structure fiber of sheath component polyethylene / core component polyester, fibers are arranged by air flow and made into a non-woven fabric by hot air, and a gutter groove structure and an opening as shown in FIG. to obtain a surface sheet of Comparative example 4 in m ^2. The obtained surface sheet had a flange width of 3 mm, a groove width of 2 mm, and a thickness (apparent thickness at the top of the flange) of 1.1 mm. Moreover, the low-density sheet | seat (nonwoven fabric) with a basic weight of 20 g / m < ² > was obtained by making into a nonwoven fabric by the air through method using the sheath component polyethylene / core component polyester 2.2 dtex * 51 mm core-sheath structure fiber.

[Performance evaluation]
For the cage sheets obtained in Examples and Comparative Examples, the fiber density of each part of the surface sheet and the contact angle of the constituent fibers of the surface sheet, and the fiber density of the low-density sheet, the orientation angle and orientation of the constituent fibers by the method described above. The angular strength was evaluated, and the density and basis weight of the low density sheet were further evaluated. Moreover, the liquid spreading, stickiness, and smoothness were evaluated by the following methods, respectively. These results are shown in Table 1 below.

<Liquid spreading>
Evaluation was performed using a highly viscous liquid. As the highly viscous liquid, suspected soft stool prepared by the following method was used. 0.5 g of the highly viscous liquid is gently dropped using a dropper while touching the top sheet of the sample, and the spread after 10 seconds is measured. When 30 seconds have elapsed since the high-viscosity liquid was dropped, an acrylic plate of 50 × 50 mm thickness 5 mm is placed on the center of the surface sheet where the high-viscosity liquid is diffusing, and is further applied to the high-viscosity liquid by a weight. The load is adjusted to 20 g / m ² . The weight and acrylic plate are removed after 1 minute of pressurization, and the spread area of the liquid after pressurization is determined. The diffusivity is obtained by using a value obtained by dividing the difference between the liquid spreading areas before and after pressurization by the liquid spreading area before pressurization as a percentage. It can be evaluated that the lower the diffusivity is, the less the liquid spreads and the liquid is transferred to the lower layer side (low density sheet side) than the top sheet. The diffusivity is preferably 30% or less, more preferably 15% or less, and most preferably a negative value.

  The suspected loose stool was prepared as follows. 100 g of skim milk [Snow Brand Milk Products Co., Ltd.] and 100 g of wheat flour [Nisshin Flour Milling Co., Ltd.] were sufficiently mixed in a container, and gradually added to 500 g of ion-exchanged water while stirring with a stirrer. Further, 500 g of ion-exchanged water was added to completely disperse these, and then the vessel was placed in a 90 ° C. water bath and stirred for 90 minutes (stirring speed: 32 rpm). After the stirring, the whole container was cooled with ice water, and 3.6 g of preservative (Proxel XL-2) was added after the inside of the container became 50 ° C. or lower. Furthermore, after sufficiently stirring with a spatula, it was put in a refrigerator and allowed to stand until the next day to obtain a stock solution. In use, ion-exchanged water was added to the stock solution to adjust the viscosity at a liquid temperature of 25 ° C. to 300 mPa · s. The viscosity of the suspected soft stool was measured with a Brookfield viscometer (manufactured by Tokyo Keiki Co., Ltd.).

<Stickiness>
In the evaluation of <Liquid Spread>, the surface state (the remaining amount of the liquid) of the surface sheet after removing the weight and the acrylic plate after 1 minute of pressure was visually observed, and the pressurized part was touched with a finger. The tactile sensation is confirmed, and the stickiness is evaluated comprehensively from both results. As for the surface state, the remaining state of the high-viscosity liquid is evaluated in three stages. If the remaining high-viscosity liquid is less than 10% of the spread portion, ◯ is 10% or more and 30% or less. When exceeding, it is set as x. The remaining amount of the liquid is preferably determined based on the presence or absence of gloss. On the other hand, the tactile sensation is ◯ when the surface of the top sheet is not wet when touched with a finger, and x when the surface is wet.

<Smoothness>
When the surface sheet of the sample is touched with a finger along both the width direction and the longitudinal direction and no roughness is felt, ◯ is given. The less the roughness, the better the fit.

  As shown in Table 1, Examples 1-4 have a low diffusivity (liquid spreading) as compared with Comparative Examples 1-4, and are excellent in a remaining liquid state after pressurization, particularly a sticky feeling. Moreover, since Examples 1-3 use the surface sheet which adjusted thickness, it is excellent in the smoothness of a surface sheet, and the feeling of mounting | wearing has improved further. In addition, when the diffusivity (liquid spreading) is 20% or less as in Examples 1 to 4, the contact angle of the constituent fibers of the surface sheet is hydrophilic but weakly hydrophilic. As shown in Example 3, especially when the diffusivity is a negative value, the surface sheet is less likely to become dirty and the liquid is quickly reduced. It has moved to the density sheet.

1 Origami sheet (absorbent article)
DESCRIPTION OF SYMBOLS 10 Top sheet 11 Back sheet 12 Low density sheet 15 Seal part 20 Gutter part 21 Gutter part top part 30 Groove part 31 Opening

Claims (5)

In a vertically long absorbent article having a surface sheet on the skin contact surface side,
The surface sheet is made of a nonwoven fabric having alternately flanges and grooves extending in the longitudinal direction of the absorbent article and having openings in the grooves, and the contact angle of the constituent fibers of the nonwoven fabric is 60 to 85 °. ,
An absorbent article in which a low-density sheet having a fiber density lower than that of the groove is disposed adjacent to the surface sheet on the non-skin contact surface side of the surface sheet.   The absorbent article according to claim 1, wherein the flange has a fiber density higher than that of the groove.   The absorption according to claim 1 or 2, wherein, in the cross section in the width direction of the absorbent article, the flange portion has a top portion that is convexly curved upward and a width that increases from the top portion toward the lower portion. Sex goods.   The absorbent article according to any one of claims 1 to 3, wherein an orientation angle of constituent fibers of the low-density sheet is 50 to 130 °.   The absorbent article according to any one of claims 1 to 4, wherein the low-density sheet is formed by sequentially laminating an upper layer and a lower layer from the top sheet side, and the upper layer has a fiber density lower than that of the lower layer.

Images