Patent Publication Number: US-2021169707-A1

Title: Absorbent article

Description:
TECHNICAL FIELD 
     The present invention relates to an absorbent article mainly used for products such as sanitary napkins, pantiliners, incontinence pads, and toiletries. 
     BACKGROUND ART 
     There is a known absorbent article where an absorber formed of, for example, cotton pulp is disposed between an impermeable back-side sheet such as a polyethylene sheet or a polyethylene-sheet-laminated nonwoven fabric and a permeable upper-side sheet such as a nonwoven fabric or a permeable plastic sheet. 
     A slim absorbent article including a thin absorber has such advantages that wearing discomfort can be reduced and that the bumps of the absorbent article are less noticeable from the outside of clothes when the absorbent article is worn (i.e., the absorbent article has less influence on the outer appearance), and is therefore popular in the market. 
     However, because the absorber is thin, the absorption capacity per unit area is small; and because the fluid retaining capacity in the thickness direction is low, the body fluid is likely to diffuse in the plane direction. For this reason, the related-art absorbent article has a disadvantage that the body fluid tends to leak particularly from a lateral edge of the absorber (side leakage). This in turn causes the wearer to feel insecure about the leakage and causes inconvenience such as having to replace absorbent articles frequently. 
     There is a known technology for preventing such side leakage in which compressed grooves are formed along the longitudinal direction on sides of an area corresponding to a body fluid discharge part of the wearer by denting the absorbent article from the skin side of the upper-side sheet toward the non-skin side, and there are many documents related to this technology. For example, Patent Document 1 discloses an absorbent article where a reference mark, which is a continuous or discontinuous contour line surrounding a predetermined area of a fluid receiving part, is provided in a position visible from the front side. 
     Also, Patent Document 2 discloses an absorbent article including an absorber where multiple compressed parts are formed by compressing an upper-side sheet and the absorber in the thickness direction of the absorbent article. The compressed parts include dot-shaped central compressed parts that are intermittently formed and disposed in a central area including the center of an excretion opening contact area facing an excretion opening of a wearer, and longitudinal compressed parts that are disposed outside of the central area in the width direction of the absorbent article and extend in the longitudinal direction of the absorbent article. The longitudinal compressed parts are depressed from the upper-side sheet toward the back-side sheet, and the central compressed parts are depressed from the back-side sheet toward the upper-side sheet. 
     RELATED-ART DOCUMENTS 
     [Patent Documents] 
     [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-126140 
     [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2013-034525 
     DISCLOSURE OF INVENTION 
     Problems to be Solved by the Invention 
     However, because the absorbent article described in Patent Document 1 does not use a thin absorber, the absorbent article is likely to cause the wearer to feel discomfort and tends to influence the outer appearance. Also, although the absorbent article described in Patent Document 2 includes multiple dot-shaped central compressed parts, the central compressed parts are provided to prevent the upper-side sheet from being damaged by heat and to draw in a body fluid discharged from the wearer by the upper-side sheet, and do not have much effect in reducing the thickness of the absorber. Thus, the absorbent article of Patent Document 2 also has disadvantages similar to those of the absorbent article of Patent Document 1. 
     Thus, Patent Documents 1 and 2 are not directed to an absorbent article using a thin absorber, and therefore do not teach problems of a thin absorber that has a small absorption capacity per unit area and where a body fluid tends to diffuse in the plane direction and side leakage tends to occur. 
     A main object of the present invention is to provide a slim absorbent article that uses a thin absorber and where the diffusion of a body fluid in the plane direction is suppressed. 
     Means for Solving the Problems 
     To solve the above problems, an aspect of the present invention provides an absorbent article including an absorber disposed between a permeable upper-side sheet and an impermeable back-side sheet. A core press depressed toward the back-side sheet is formed on at least a surface of the absorber facing the upper-side sheet such that the thickness of the absorber is reduced in the thickness direction, right and left compressed grooves are formed along the longitudinal direction of the absorbent article on at least the sides of an area corresponding to a body fluid discharge part of a wearer, and a high absorption part having a greater absorption capacity per unit area than other parts is formed at least between the right and left compressed grooves of the absorber. 
     Advantageous Effect of the Invention 
     As described above, the present invention makes it possible to suppress the diffusion of a body fluid in the plane direction in a slim absorbent article using a thin absorber and to particularly prevent side leakage of the body fluid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially-cutaway view of a sanitary napkin  1  according to the present invention; 
         FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 ; 
         FIG. 3  is a plan view of an absorber  4 ; 
         FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 3 ; 
         FIG. 5  is a plan view of an absorber  4  according to a variation; 
         FIG. 6  is a plan view of an absorber  4  according to a variation; 
         FIG. 7  is a plan view of an absorber  4  according to a variation; 
         FIG. 8  is a cross-sectional view of a sanitary napkin  1  according to another embodiment; and 
         FIG. 9  is a cross-sectional view of a sanitary napkin  1  according to another embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention are described below with reference to the drawings. 
     &lt;Basic Structure of Sanitary Napkin&gt; 
     As illustrated in  FIGS. 1 and 2 , a sanitary napkin  1  according to the present invention includes an impermeable back-side sheet  2  formed of, for example, a polyethylene sheet, a permeable upper-side sheet  3  that allows, for example, menstrual blood and a vaginal discharge (which are hereinafter collectively referred to as a “body fluid”) to smoothly pass through, an absorber  4  formed of, for example, cotton pulp or synthetic pulp and disposed between the sheets  2  and  3 , and side nonwoven fabrics  7  that are provided on the lateral sides of a skin-contact surface and extend along substantially the entire length in the longitudinal direction. In the periphery of the absorber  4 , at the edges in the longitudinal direction of the absorber  4 , the outer edges of the back-side sheet  2  and the upper-side sheet  3  are bonded together with an adhesive such as a hot melt or a bonding method such as heat sealing or ultrasonic sealing. Also, at the side edges of the absorber  4 , portions of the back-side sheet  2  and the side nonwoven fabrics  7  extending laterally beyond the absorber  4  are bonded together with an adhesive such as a hot melt or a bonding method such as heat sealing or ultrasonic sealing. A pair of right and left wing flaps W are formed at the absorber side positions that correspond to an area 
     H corresponding to a body fluid discharge part in the longitudinal direction. In the illustrated example, to keep the shape of the absorber  4  and improve its diffusivity, the absorber  4  is enveloped in an enveloping sheet  5  formed of, for example, crepe paper or a nonwoven fabric. However, the enveloping sheet  5  may be omitted. Also, although not shown, a second sheet formed of, for example, a hydrophilic nonwoven fabric and having substantially the same shape as the upper-side sheet  3  may be provided adjacent to the non-skin side of the upper-side sheet  3 . 
     Below, the structure of the sanitary napkin  1  is described in more detail. The back-side sheet  2  may be made of a sheet material such as polyethylene having at least water impermeability. The back-side sheet  2  is preferably formed of a material having moisture permeability to prevent stuffiness. As the water-impermable and moisture-permeable sheet, a microporous sheet is preferably used. A microporous sheet is obtained by melt-mixing an inorganic filler with an olefin resin such as polyethylene or polypropylene to form a sheet, and by stretching the sheet uniaxially or biaxially. On the non-skin side (outer surface) of the back-side sheet  2 , one or more streaks of adhesive layers (not shown) are formed along the napkin longitudinal direction to fix the sanitary napkin  1  to underwear when the sanitary napkin  1  is worn on the body. The back-side sheet  2  may also be made of a polyethylene-laminated nonwoven fabric (a nonwoven fabric laminated with a polyethylene film) that is formed by stacking a plastic film and a nonwoven fabric. 
     The permeable upper-side sheet  3  is preferably made of a porous or nonporous nonwoven fabric or a porous plastic sheet. Examples of fiber materials of the nonwoven fabric include synthetic fibers formed of olefin such as polyethylene or polypropylene, polyester, or polyamide, regenerated fibers such as rayon and cupra, and natural fibers such as cotton. The nonwoven fabric may be produced by any appropriate production method such as spunlacing, spunbonding, thermal bonding, melt-blowing, or needle punching. Among these production methods, spunlacing has an advantage in terms of flexibility and draping characteristics, and thermal bonding has an advantage in terms of bulkiness and compression restoration. When a large number of through holes are formed in the upper-side sheet  3 , the sanitary napkin  1  can quickly absorb a body fluid and its dry touch property is improved. Although either long fibers or short fibers may be used for the nonwoven fabric, short fibers are preferably used to give a texture of a towel cloth. Also, to facilitate embossing, olefin fibers made of, for example, polyethylene or polypropylene with a relatively low melting point are preferably used. Also, bicomponent fibers may be used for the nonwoven fabric. 
     Examples of bicomponent fibers include a core-in-sheath fiber including a high-melting-point fiber as a core and a low-melting-point fiber as a sheath, a side-by-side fiber, and a split fiber. 
     As illustrated in the transverse sectional view of  FIG. 2 , the width of the upper-side sheet  3  is slightly longer than the width of the absorber  4 , and the upper-side sheet  3  merely covers the absorber  4  within a predetermined section that includes the area H corresponding to the body fluid discharge part and extends in the napkin longitudinal direction. The side nonwoven fabrics  7  different from the upper-side sheet  3  are provided outside of the absorber  4 . The side nonwoven fabrics  7  are formed of a non-woven fabric material on which a water repellent treatment or a hydrophilic treatment is performed depending on a purpose such as preventing penetration of menstrual blood or a vaginal discharge or improving the feel. 
     The side nonwoven fabrics  7  may be produced using natural fibers, synthetic fibers, or regenerated fibers as a material according to any appropriate production method. A nonwoven fabric having a reduced basis weight and breathability is preferably used to reduce coarseness and prevent stuffiness. Specifically, a nonwoven fabric produced to have a basis weight of 13-23 g/m 2  is preferably used. Also, a water-repellent nonwoven fabric coated with a silicone-based, paraffin-based, or alkylchromic chloride-based water repellent is preferably used to effectively prevent permeation of a body fluid. 
     As illustrated in  FIG. 2 , an outer portion of each of the side nonwoven fabrics  7  located outside of a middle portion in the width direction is bonded with an adhesive such as a hot melt across a section from a predetermined inner position to an outer edge of the back-side sheet  2  to form a predetermined flap at a predetermined position. The flaps form a pair of right and left wing flaps W on the sides positions that correspond to the area H corresponding to the body fluid discharge part in the longitudinal direction. Adhesive layers (not shown) are provided on the outer surface of the back-side sheet  2  at positions corresponding to the wing flaps W. When the sanitary napkin  1  is attached to shorts, the wing flaps W are folded back toward the opposite side along folding lines RL ( FIG. 1 ) at their base ends and are wound around the crotch of the shorts to fix the sanitary napkin  1 . On the other hand, the inside portions of the side nonwoven fabrics  7  are stacked on the skin side of the upper-side sheet  3  and bonded to the absorber  4  (the skin side of the upper-side sheet  3 ). 
     &lt;Absorber&gt; 
     The absorber  4  disposed between the back-side sheet  2  and the upper-side sheet  3  is formed of, for example, pulp and a superabsorbent polymer. The superabsorbent polymer is mixed in the pulp constituting the absorber in the form of, for example, granular powder. The pulp may be made of cellulose fibers such as chemical pulp or dissolving pulp made from wood, or synthetic cellulose fibers such as rayon or acetate. In terms of the function and the price, softwood pulp with a long fiber length is more preferable than hardwood pulp. 
     The sanitary napkin  1  is a thin slim napkin using the absorber  4  with a low basis weight. The basis weight of the pulp is 50-300 g/m 2 , and is preferably 80-220 g/m 2 . The basis weight of the superabsorbent polymer is 30-180 g/m 2 , and is preferably 50-160 g/m 2 . The basis weights of the pulp and the superabsorbent polymer are not necessarily constant, and may be changed depending on the portions of the absorber. For example, as described later in detail, a high absorption part  15  where the basis weights of the pulp and the superabsorbent polymer are high may be formed in an area corresponding to the area H that corresponds to the body fluid discharge part of the wearer. 
     Synthetic fibers may also be added to the absorber  4 . The synthetic fibers may be made of, for example, polyolefin such as polyethylene or polypropylene, polyester such as polyethylene terephthalate or polybutylene terephthalate, polyamide such as nylon, or a copolymer of these polymers. Also, a mixture of two types of synthetic fibers may be used. Also, bicomponent fibers may be used. Examples of bicomponent fibers include a core-in-sheath fiber including a high-melting-point fiber as a core and a low-melting-point fiber as a sheath, a side-by-side fiber, and a split fiber. When using hydrophobic fibers as the synthetic fibers, the hydrophobic fibers are preferably surface-treated with a hydrophilic agent to have an affinity to the body fluid. 
     As illustrated in  FIGS. 3 and 4 , a core press  10  depressed toward the back-side sheet  2  (non-skin side) is formed in at least a surface (skin side surface) of the absorber  4  facing the upper-side sheet  3 . The core press  10  is formed to reduce the thickness of the absorber  4  in the thickness direction. The core press  10  is formed by compressing the absorber  4  in a predetermined pattern at predetermined intervals instead of compressing the entire surface of the absorber  4 . Because core-press-formed portions of the absorber  4  where the core press  10  is formed are compressed in the thickness direction, fibers in portions where the core press  10  is not formed are drawn by the core-press-formed portions, and the portions where the core press  10  is not formed are influenced and compressed to some extent. As a result, the thickness of the entire absorber  4  is reduced in the thickness direction. The “thickness of the absorber  4 ” indicates the thickness of the entire absorber  4 , and indicates the maximum thickness measured at the thickest portion of the absorber  4 . 
     When the thickness of the absorber  4  before forming the core press  10  is t 0  and the thickness of the absorber  4  after forming the core press  10  is t, the ratio t/t 0  of the thickness after being reduced by forming the core press  10  is preferably about 1/10 to about 7/10. If the ratio is less than 1/10, the absorber becomes hard and the wearing comfort is reduced. On the other hand, if the ratio is greater than 7/10, the effect of compression by the core press  10  becomes small and the thickness of the absorber  4  increases. The ratio may be changed by adjusting, for example, the compression depth of the core press  10 , the interval between adjacent core presses, and the plane pattern of the core press  10 . 
     In the illustrated example, the core press  10  is formed by compressing the absorber  4  only from the skin side (the surface facing the upper-side sheet  3 ). As a result, U-shaped recesses are formed on the skin side of the absorber  4 , and the non-skin side (the surface facing the back-side sheet  2 ) of the absorber  4  becomes substantially flat. Such processing may be performed by passing the absorber through a gap between a patterned roller having multiple protrusions on its surface and an anvil roller having a flat surface. On the other hand, although not shown, U-shaped recesses may be formed on both of the skin side and the non-skin side of the absorber  4  by compressing the absorber  4  from both of the skin side and the non-skin side. Such processing may be performed by passing the absorber  4  through a gap between a first patterned roller having multiple protrusions on its surface and a second patterned roller having protrusions formed at positions corresponding to the protrusions of the first patterned roller. When at least the skin side of the absorber  4  is compressed, a body fluid entering through the upper-side sheet  3  flows into the recesses of the core press  10 , can smoothly diffuse along the core press  10 , and can be absorbed by the absorber  4  while diffusing. 
     As illustrated in  FIG. 3 , the core press  10  is preferably formed in the same pattern on substantially the entire absorber  4 . That is, the core press  10  is also formed in the area H corresponding to the body fluid discharge part of the wearer in the same pattern as in the other areas. This makes it possible to reduce the thickness of the entire absorber  4 , to effectively reduce the wearing discomfort, and to effectively reduce the influence on the outer appearance. 
     The core press  10  can be formed in any pattern as long as the thickness of the absorber  4  can be reduced in the thickness direction. However, as illustrated in  FIG. 3 , the core press  10  preferably includes multiple linear pressed parts  11  that are continuous or intermittent in a predetermined portion and formed between edges of the absorber  4 . The linear pressed parts  11  are not formed in a middle portion that does not reach the outer edges of the absorber  4 . Instead, each linear pressed part  11  is formed between one of the front, rear, right, and left edges of the absorber  4  and another one of the front, rear, right, and left edges. Forming the linear pressed parts  11  between the edges of the absorber  4  makes it possible to compress the entire absorber  4  and to effectively reduce its thickness. 
     The core press  10  preferably includes a grid-like pattern composed of first linear pressed parts  11   a  that are inclined to one side in the width direction and arranged in the longitudinal direction at predetermined intervals and second linear pressed parts  11   b  that are inclined to the other side in the width direction to intersect the first linear pressed parts  11   a  and arranged in the longitudinal direction at predetermined intervals. 
     Forming the core press  10  in a grid-like pattern makes it possible to more effectively reduce the thickness of the absorber  4 , and to more effectively reduce the wearing discomfort and suppress the influence on the outer appearance. The first linear pressed parts  11   a  and the second linear pressed parts  11   b,  respectively, are preferably arranged at substantially the same interval such that a large number of rectangular cells having a square or rhombic shape and defined by the linear pressed parts  11   a  and  11   b  are arranged. Although the substantially rectangular cells surrounded by the linear pressed parts  11   a  and  11   b  are not directly compressed, their thickness is influenced by the linear pressed parts  11   a  and  11   b  and is made smaller than the original thickness. 
     The intersecting angle between the first linear pressed parts  11   a  and the second linear pressed parts  11   b  is substantially a right angle in the illustrated example. However, the intersecting angle may be between about 30 degrees and about 150 degrees. The first linear pressed parts  11   a  and the second linear pressed parts  11   b  are preferably inclined with respect to the width direction of the sanitary napkin  1 . With this configuration, when the right and left legs are moved back and forth during, for example, walking and a force is applied to the sanitary napkin  1  in a torsional direction due to a pressure from the inside of the groin, the absorber  4  can smoothly deform in an oblique direction along the linear pressed parts  11   a  and  11   b  and can smoothly follow the movement of the body. Also, because a body fluid flows in the width direction of the sanitary napkin  1  along the linear pressed parts  11   a  and  11   b , this configuration can prevent side leakage compared with a case where linear pressed parts are formed to extend in a direction parallel to the width direction. To facilitate deformation in the oblique direction and prevent side leakage as described above, the linear pressed parts  11   a  and  11   b  are preferably inclined at an angle greater than or equal to 30 degrees with respect to the width direction of the sanitary napkin  1 . 
     To effectively reduce the thickness of the absorber  4 , as illustrated in the  FIG. 3 , a length “a” of each side of the cells defined by the first linear pressed parts  11   a  and the second linear pressed parts  11   b  is preferably between 4 mm and 10 mm. If the length “a” is less than 4 mm, the distance between the linear pressed parts  11   a  and  11   b  becomes too close. As a result, the absorber  4  becomes hard, and the wearing comfort is reduced. On the other hand, if the length “a” is greater than 10 mm, the central portion of each cell bulges toward the skin side, and the thickness of the entire absorber  4  cannot be sufficiently reduced. The width of each of the linear pressed parts  11   a  and  11   b  is preferably between 0.5 mm and 3 mm. 
     To effectively reduce the thickness of the absorber  4 , as illustrated in  FIGS. 3 and 4 , a central pressed part  16  shaped like, for example, a circular or polygonal dot may be formed in the central portion of each cell which is apart from the linear pressed parts  11   a  and  11   b . This configuration makes it possible to suppress the central portion of each cell from bulging toward the skin side, and makes it possible to effectively reduce the thickness of the entire absorber  4  without much increasing the hardness of the absorber  4 . Also, a body fluid penetrated into each cell can smoothly diffuse toward the central pressed part  16  with high density due to capillary action. This in turn makes it possible to improve the diffusivity and to quickly absorb the body fluid. When the central pressed part  16  is formed, the length “a” of each side of the cell may be made greater than the length in a case where the central pressed part  16  is not formed. For example, even if the length “a” is increased up to about 15 mm, the thickness of the absorber  4  can be reduced without problem. 
     The planar shape of each cell defined by the core press  10  may be a polygon having five or more sides instead of a quadrangle such as a square or a rhombus described above. In the above embodiment, the linear pressed parts  11   a  and  11   b  are formed as continuous lines. However, the linear pressed parts  11   a  and  11   b  may be formed as discontinuous lines composed of multiple dots arranged at intervals. 
     As illustrated in  FIGS. 3 and 4 , on the surface of the absorber  4  facing the upper-side sheet  3 , in addition to the core press  10 , right and left compressed grooves  12  are formed along the longitudinal direction of the sanitary napkin  1  on at least the sides of the area H corresponding to the body fluid discharge part of the wearer. Forming the compressed grooves  12  makes it possible to block the body fluid diffusing in the width direction of the sanitary napkin  1  from the area H corresponding to the body fluid discharge part of the wearer through the core press  10 , and to change the direction of the flow to a direction along the longitudinal direction of the sanitary napkin  1  in which the compressed grooves  12  extend. This in turn makes is possible to prevent the body fluid from diffusing to the lateral edges of the absorber  4 , and to reliably prevent the side leakage. 
     Similarly to the core press  10 , the compressed grooves  12  may be composed of U-shaped recesses that are formed only on the skin side of the absorber  4  by compressing the absorber  4  only from the skin side, or composed of U-shaped recesses formed on both of the skin side and the non-skin side of the absorber  4  by compressing the absorber  4  from the skin side and the non-skin side. 
     In the embodiment illustrated in  FIG. 3 , the compressed grooves  12  are formed on the sides of the area H corresponding to the body fluid discharge part of the wearer to extend in the longitudinal direction. That is, the compressed grooves  12  are composed of arc lines that are disposed apart from each other in the width direction on the right and left sides of the central portion of the sanitary napkin  1 . The compressed grooves  12  extend in the longitudinal direction on the sides of the area H corresponding to the body fluid discharge part of the wearer and have a length that is substantially the same as the area H corresponding to the body fluid discharge part. Each of the compressed grooves  12  preferably has a curved shape that protrudes to the outermost position in the width direction at the center in the longitudinal direction. 
     As a variation, as illustrated in  FIG. 5 , the compressed groove  12  may be formed as an annular line that surrounds the area H corresponding to the body fluid discharge part of the wearer. This configuration makes it possible to suppress the diffusion in the longitudinal direction in addition to the diffusion in the width direction, and therefore makes it possible to effectively prevent the leakage from the lateral and longitudinal edges of the absorber  4 . In this case, the compressed groove  12  preferably has a circular, elliptical, or oblong planar shape. 
     As illustrated in the  FIG. 6 , the compressed groove  12  preferably includes multiple longitudinal compressed grooves  12   a  on each side of the area H corresponding to the body fluid discharge part of the wearer. The longitudinal compressed grooves  12   a  extend in the longitudinal direction and are apart from each other in the width direction. In the example illustrated in  FIG. 6 , two longitudinal compressed grooves  12   a,  which are apart from each other in the width direction, are formed on each side of the area H corresponding to the body fluid discharge part of the wearer. One of the two longitudinal compressed grooves  12   a  located on the outer side is implemented by a longitudinally-extending portion of the annular line surrounding the area H corresponding to the body fluid discharge part of the wearer, and another one of the two longitudinal compressed grooves  12   a  located on the inner side is implemented by one of arc lines that are disposed apart from each other in the width direction on the right and left sides of the central portion of the sanitary napkin  1 . This configuration makes it possible to more reliably prevent the diffusion of the body fluid in the width direction. 
     The multiple longitudinal compressed grooves  12   a  are preferably arranged concentrically around substantially the center of the area H corresponding to the body fluid discharge part of the wearer, and preferably have substantially parallel curved shapes that protrude outward. To prevent the diffusion of the body fluid in the width direction, the compressed grooves  12   a  in the innermost positions in the width direction are preferably positioned on the sides of an area that substantially corresponds to the vaginal opening of the wearer. 
     In this case, the longitudinal compressed groove  12   a  disposed in the laterally-outer position preferably extends in the forward and backward longitudinal directions longer than the longitudinal compressed groove  12   a  disposed in the laterally-inner position. With this configuration, the body fluid diffusing outward in the width direction around an end of the longitudinal compressed groove  12   a  disposed in the laterally-inner position can be blocked by the longitudinal compressed groove  12   a  disposed in the laterally-outer position, and the diffusion of the body fluid in the laterally-outward direction can be prevented more reliably. 
     Also, as illustrated in  FIG. 7 , the longitudinal compressed grooves  12   a  disposed in the laterally-inner positions may be implemented by longitudinally-extending side portions of a circular annular line disposed to surround an area corresponding to the vaginal opening of the wearer. That is, the compressed grooves may be formed in a pattern composed of double annular lines where a compressed groove  12  formed of a circular annular line surrounding an area corresponding to the vaginal opening is disposed inside of a compressed groove  12  formed of an elliptical annular line that is long in the longitudinal direction and surrounds the area H corresponding to the body fluid discharge part. 
     As illustrated in  FIG. 7 , one or more front lateral compressed grooves  12   b  and one or more rear lateral compressed grooves  12   b  may be formed in front of and behind the area H corresponding to the body fluid discharge part of the wearer. The front and rear lateral compressed grooves  12   b  extend in the width direction of the sanitary napkin  1  and are spaced in the longitudinal direction. Providing the front and rear lateral compressed grooves  12   b  extending in the width direction makes it possible to prevent the diffusion of the body fluid in the longitudinal direction and to prevent the leakage from the front and rear ends of the absorber  4 . Also, when the sanitary napkin  1  is worn, the front and rear lateral compressed grooves  12   b  function as bending guide lines that guide the absorber  4  to deform along the front and rear round portions of the body. The front and rear lateral compressed grooves  12   b  may be implemented by portions of the annular line extending in the width direction, or may be implemented by independent arc lines extending in the width direction and disposed apart from each other in the longitudinal direction of the sanitary napkin  1 . Also, as in the illustrated example, multiple lateral compressed grooves  12   b,  “four” in this example, may be formed by combining an annular line and arc lines. When four lateral compressed grooves  12   b  are formed on each of the front and rear sides as in the illustrated example, the outermost lateral compressed groove  12   b  is preferably implemented by a portion of an elliptical annular line extending in the width direction, the innermost lateral compressed groove  12   b  is preferably implemented by a portion of a circular annular line extending in the width direction, and two lateral compressed grooves  12   b  in the middle are preferably implemented by independent arc lines. With this configuration, the innermost annular compressed groove can suppress the diffusion of the body fluid in the vicinity of the vaginal opening; when the body fluid sufficiently diffuses to saturate the area and diffuses outside of the area, the middle arc-shaped lateral compressed grooves  12   b  can suppress the outward diffusion of the body fluid in the longitudinal direction; and the body fluid can be reliably retained in an area surrounded by the outermost annular compressed groove. 
     As illustrated in  FIGS. 3 and 5-7 , the core press  10  is preferably omitted in positions where the core press  10  overlaps the compressed grooves  12  and in the vicinity of the compressed grooves  12  such that non-pressed parts  14  with a predetermined width are formed around the compressed grooves  12 . That is, the core press  10  is not formed in areas corresponding to the compressed grooves  12  and in areas with a predetermined with around the compressed grooves  12  so that non-pressed areas (non-pressed parts  14 ) are formed between the compressed grooves  12  and the core press  10 . With the non-pressed parts  14  formed around the compressed grooves  12 , the body fluid diffused along the core press  10  is temporarily retained in the non-pressed parts  14  before reaching the compressed grooves  12 . This configuration makes it possible to quickly lower the diffusion rate of the body fluid diffusing along the core press  10 , and enables the body fluid to smoothly change its direction and flow along the compressed grooves  12 . Also, because even the outer sides of the compressed grooves  12  are not connected to the core press  10 , the body fluid diffusing along the compressed grooves  12  is prevented from diffusing outward along the core press  10 , and the body fluid can be reliably kept within the area surrounded by the compressed grooves  12 . 
     The non-pressed part  14  is formed around the entire periphery of each compressed groove  12  so that the compressed groove  12  and the core press  10  are not directly connected to each other. The width of the non-pressed part  14  is preferably between 0.5 mm and 5 mm to ensure its function as a body fluid buffer zone and prevent the thickness of the absorber  4  from increasing. 
     The non-pressed parts  14  are preferably formed also around the longitudinal compressed grooves  12   a  and the lateral compressed grooves  12   b.  Hereinafter, the term “compressed groove(s)  12 ” may also encompass the longitudinal compressed grooves  12   a  and the lateral compressed grooves  12   b.    
     As illustrated in  FIG. 3 , a groove width A of the compressed groove  12  is preferably greater than a groove width B of the linear pressed part  11  of the core press  10  (A&gt;B). This configuration makes the body fluid diffusing along the compressed groove  12  less likely to move to the core press  10 , and makes it possible to suppress the body fluid from diffusing outside of the compressed groove  12 . The ratio A/B between the groove widths A and B is preferably between 1.5 and 3. 
     In forming the core press  10  and the compressed grooves  12  on the absorber  4 , the core press  10  and the compressed grooves  12  may be simultaneously formed using a patterned roll on which protrusions corresponding to the core press  10  and the compressed grooves  12  are formed. Alternatively, the compressed grooves  12  may be formed after forming the core press  10 . 
     In the sanitary napkin  1 , as illustrated in  FIGS. 3 and 4 , the high absorption part  15 , which has an absorption capacity per unit area greater than that of other parts, is formed at least between the right and left compressed grooves  12  of the absorber  4 . The area between the right and left compressed grooves  12  includes the area H corresponding to the body fluid discharge part of the wearer. As illustrated in the  FIG. 3 , when the compressed grooves  12  implemented by independent arc lines are disposed on the right and left sides, the high absorption part  15  is formed in an area that includes the area sandwiched between the compressed grooves  12 . Also, as illustrated in  FIG. 5 , when the compressed groove  12  is implemented by an annular line formed to surround the area H corresponding to the body fluid discharge part, the high absorption part  15  is formed in an area surrounded by the compressed groove  12 . Further, as illustrated in  FIGS. 6 and 7 , when compressed grooves are formed inside of a compressed groove implemented by an annular line formed to surround the area H corresponding to the body fluid discharge part of the wearer, the high absorption part  15  is formed within an area surrounded by the outermost compressed groove  12 . Forming the high absorption part  15  at least between the right and left compressed grooves  12  indicates that when the independent arc-shaped compressed grooves  12  are formed on the right and left sides as illustrated in  FIG. 3 , the high absorption part  15  may be formed to extend to one or both of areas before and after the area sandwiched between the compressed grooves  12 . In the illustrated example, the high absorption part  15  is formed to extend to both of the areas. The high absorption part  15  is formed in at least a part of the area between the right and left compressed grooves  12 , and is preferably formed in the entire area. As illustrated in  FIGS. 5 through 7 , when the compressed groove  12  is implemented by an annular line surrounding the area H corresponding to the body fluid discharge part of the wearer, the high absorption part  15  is preferably formed in substantially the entire area surrounded by the compressed groove  12 . 
     The high absorption part  15  has a greater absorption capacity per unit area than other parts. Providing the high absorption part  15  in the area H corresponding to the body fluid discharge part of the wearer makes it possible to sufficiently absorb and retain a discharged body fluid by the high absorption part  15 , and makes it possible to suppress the body fluid from diffusing out of the high absorption part  15 . This configuration also makes it possible to prevent the area surrounded by the compressed groove  12  from becoming out of capacity (saturated) and prevent the body fluid from flowing and diffusing out of the area. 
     The absorption capacity per unit area is measured as described below.
     (1) While the napkin is in a taut state (a state where the napkin is spread along a plane and has no wrinkle or fold), the napkin is cut into the high absorption part  15  and other parts, and the areas of these parts are measured. Before this step, the back-side sheet  2  and the upper-side sheet  3  are removed. (2) The parts are placed in separate mesh bags, and the mouths of the mesh bags are closed. Then, the mesh bags are immersed in a 0.9 wt % physiological saline solution and left for 30 minutes.   (3) The parts are dehydrated with a centrifugal dehydrator ( 10 G) for 3 minutes.   (4) The absorption capacity per unit area of each of the parts is calculated according to the following formula.   

     absorption capacity per unit area (g/cm 2 )=((weight after dehydration (g)−(weight before immersion in liquid (g))/area of part (cm 2 )) 
     The absorption capacity per unit area of the high absorption part  15  measured as described above is preferably between 0.3 g/cm 2  and 2.0 g/cm 2 , and preferably between 0.3 g/cm 2  and 1.0 g/cm 2 . Also, the absorption capacity per unit area of the high absorption part 15 is 1.5 to 5 times, preferably 1.5 to 2.5 times, greater than the absorption capacity per unit area of other parts. 
     The absorption capacity per unit area may be increased, for example, by increasing the basis weight of the pulp and the superabsorbent polymer or by changing the type of the superabsorbent polymer to one having a greater absorption amount. In the case where the basis weight of the pulp and the superabsorbent polymer is increased, if only the basis weight of the superabsorbent polymer is increased, the corresponding area becomes hard, and the wearer is likely to feel the graininess of the superabsorbent polymer. Therefore, it is preferable to also increase the basis weight of the pulp by substantially the same ratio as the increased ratio of the superabsorbent polymer. The increased basis weight of the pulp and the superabsorbent polymer in the high absorption part 15 is 1.5 to 5 times, preferably 1.5 to 2.5 times, greater than that of other areas. As a result of increasing the basis weight of the pulp and the superabsorbent polymer, the thickness of the high absorption part  15  increases compared to other areas. However, because the core press  10  is also formed in the high absorption part  15 , even if the thickness slightly increases, the wearing comfort is not influenced. Specifically, although it varies depending on the thickness of the entire absorber  4 , the difference between the thickness of the high absorption part  15  and the thickness of other areas is preferably less than or equal to 1 mm. 
     When the absorption capacity per unit area is increased by increasing the basis weight of the pulp and the superabsorbent polymer, the rigidity of the high absorption part  15  becomes relatively high and the rigidity of other parts becomes relatively low. This achieves an effect that while the area H corresponding to the body fluid discharge part of the wearer is in close contact with the body, other parts can smoothly follow the movement of the body. 
     When the absorption capacity per unit area is increased by changing the types of superabsorbent polymers, a superabsorbent polymer with a large water absorption amount measured according to JIS K7223 may be used for the high absorption part  15 . 
     When multiple longitudinal compressed grooves  12   a  are formed at least on each side of the area H corresponding to the body fluid discharge part of the wearer as illustrated in  FIG. 6 , the absorption capacity per unit area of the absorber in the inner area inside of the longitudinal compressed grooves  12   a  may be made higher than that in the outer area outside of the longitudinal compressed grooves. By gradually lowering the absorption capacity per unit area from the inner area toward the outer area bordered by the longitudinal compressed grooves  12   a,  the body fluid is sufficiently absorbed in the inner area before diffusing to the outer area. Thus, this configuration makes it possible to further suppress the diffusion of the body fluid and to more reliably prevent the side leakage. In the example illustrated in  FIG. 6 , two longitudinal compressed grooves  12   a  are formed on each side. A central portion between the inner longitudinal compressed grooves  12   a  is set as a high absorption part  15   a  with the highest absorption capacity per unit area, an annular portion between the outer longitudinal compressed grooves  12   a  and the inner longitudinal compressed grooves  12   a  is set as a middle absorption part  15   b  that has an absorption capacity per unit area lower than that of the high absorption part  15   a  in the center, and a portion outside of the outer longitudinal compressed grooves  12   a  (the compressed groove  12 ) is set as a low absorption part with the lowest absorption capacity per unit area. 
     In the sanitary napkin  1  configured as described above, the thickness of the absorber  4  is reduced in the thickness direction by forming the core press  10  on the absorber  4 . Thus, the sanitary napkin  1  is made as a slim napkin that does not much affect the outer appearance. However, depending on the use condition, the body fluid may diffuse along the core press  10  and may particularly leak from the lateral edges. For this reason, the left and right compressed grooves  12  are formed along the longitudinal direction of the sanitary napkin  1  on at least the sides of the area H corresponding to the body fluid discharge part of the wearer to block the body fluid diffusing toward the lateral edges of the absorber  4 . Also, the high absorption part  15  with an absorption capacity per unit area higher than that of other parts is formed at least between the right and left compressed grooves  12  of the absorber  4  so that a discharged body fluid can be prevented from diffusing in the plane direction and can be absorbed and retained in the absorber  4 . 
     OTHER EMBODIMENTS 
     In the above embodiment, as illustrated in  FIG. 2 , the compressed grooves  12  are formed by compressing only the absorber  4  or both of the enveloping sheet  5  and the absorber  4  from the skin side of the absorber  4 , and the skin side of the compressed grooves  12  is covered by the upper-side sheet  3  such that spaces are formed in the compressed grooves  12 . Alternatively, as illustrated in  FIG. 8 , the compressed grooves  12  may be formed by compressing the upper-side sheet  3  and the absorber  4  together from the skin side of the upper-side sheet  3  in a state where the upper-side sheet  3  is placed on the skin side of the absorber  4  so that the upper-side sheet  3  is present on the side surface and the bottom of each compressed groove  12 . With the configuration where the compressed groove  12  is formed by compressing the upper-side sheet  3  and the absorber  4  together, the body fluid flowing outward in the width direction on the surface of the upper-side sheet  3  enters the recess of the compressed groove  12  and is absorbed by the absorber  4  through the compressed groove  12 . This configuration makes it possible to prevent side leakage caused by the lateral flow of the body fluid on the surface. Also, by compressing the upper-side sheet  3  and the absorber  4  together, the upper-side sheet  3  and the absorber  4  between the right and left compressed grooves  12  are united and closely contact the body fluid discharge part of the wearer. This in turn makes it possible to improve the fit on the body, improve the body fluid absorption capability, and improve the wearing comfort. 
     Also, as illustrated in  FIG. 9 , after forming the right and left compressed grooves  12  by compressing only the absorber  4  or both of the enveloping sheet  5  and the absorber  4  from the skin side of the absorber  4  and stacking the upper-side sheet  3  on the skin side of the absorber  4 , compressed grooves  13  may be formed by compressing the upper-side sheet  3  and the absorber  4  together from the skin side of the upper-side sheet  3  such that the upper-side sheet  3  is present on the side surface and the bottom of each compressed groove  13 . The compressed grooves  13  are disposed outside of and apart from the compressed grooves  12  in the width direction. 
     Providing the compressed grooves  13  formed by compressing the upper-side sheet  3  and the absorber  4  together at positions outside of the compressed grooves  12  formed by compressing only the absorber  4  makes it possible to further improve the leakage prevention effect. 
     Preferred embodiments of the present invention are described below as appendices. 
     (Appendix 1) 
     According to an embodiment of Appendix 1, an absorbent article includes an absorber disposed between a permeable upper-side sheet and an impermeable back-side sheet. A core press depressed toward the back-side sheet is formed on at least a surface of the absorber facing the upper-side sheet such that a thickness of the absorber is reduced in a thickness direction, right and left compressed grooves are formed along the longitudinal direction of the absorbent article on at least the sides of an area corresponding to a body fluid discharge part of a wearer, and a high absorption part having a greater absorption capacity per unit area than other parts is formed at least between the right and left compressed grooves of the absorber. 
     In the embodiment of Appendix 1, the thickness of the absorber is reduced in the thickness direction by forming the core press on the absorber. In an absorber with a core press, the body fluid may diffuse along the core press where the density of fibers is increased by compression, and leakage (side leakage) from the lateral edges may occur depending on the use condition. However, in the present invention, right and left compressed grooves are formed along the longitudinal direction of the absorbent article on at least the sides of the area corresponding to the body fluid discharge part of the wearer to block the diffusion of the body fluid to the lateral edges of the absorber, and a high absorption part having a greater absorption capacity per unit area than other parts is formed at least between the right and left compressed grooves of the absorber. This configuration makes it possible to prevent the diffusion of a discharged body fluid in the plane direction and to absorb and retain the body fluid in the absorber. 
     Accordingly, this embodiment makes it possible to provide a slim absorbent article that uses a thin absorber and where the diffusion of a body fluid in the plane direction, particularly in the width direction, is suppressed. 
     (Appendix 2) 
     An embodiment of Appendix 2 provides the absorbent article described in Appendix 1 where the compressed grooves are formed to surround the area corresponding to the body fluid discharge part of the wearer. 
     According to the embodiment of Appendix 2, the compressed grooves are formed to surround the area corresponding to the body fluid discharge part of the wearer. This embodiment makes it possible to suppress the diffusion in the longitudinal direction in addition to the diffusion in the width direction, and thereby makes it possible to reliably prevent the leakage from the edges of the absorber. 
     (Appendix 3) 
     An embodiment of Appendix 3 provides the absorbent article described in Appendix 1 or 2 where multiple compressed grooves are formed at least on each side of the area corresponding to the body fluid discharge part of the wearer, and the absorption capacity per unit area of the absorber in an inner area inside of the compressed grooves is greater than the absorption capacity per unit area of the absorber in an outer area outside of the compressed grooves. 
     In the embodiment of Appendix 3, when multiple compressed grooves are formed on each side, the absorption capacity per unit area is changed gradually in areas bordered by the compressed grooves. This configuration makes it possible to further suppress the diffusion of the body fluid and more reliably prevent the side leakage. The absorption capacity per unit area can be adjusted by changing the basis weight of the pulp and the superabsorbent polymer or by changing the types of superabsorbent polymers. 
     (Appendix 4) 
     An embodiment of Appendix 4 provides the absorbent article described in any one of Appendices 1-3 where the core press includes multiple linear pressed parts that are formed between edges of the absorber and are continuous or omitted in the compressed grooves. 
     In the embodiment of Appendix 4, the core press includes the linear pressed parts formed between the edges of the absorber. This makes it possible to reliably reduce the thickness of the absorber. 
     (Appendix 5) 
     An embodiment of Appendix 5 provides the absorbent article described in Appendix 4 where the core press includes multiple first linear pressed parts that are arranged at predetermined intervals in the longitudinal direction and inclined to one side in a width direction, and multiple second linear pressed parts that are arranged in the longitudinal direction at predetermined intervals, inclined to another side in the width direction, and intersect the first linear pressed parts. 
     In the embodiment of Appendix 5, the core press is formed in a grid-like pattern including the first linear pressed parts and the second linear pressed parts inclined in different directions. With this configuration, the body fluid diffuses along the first linear pressed parts and the second linear pressed parts. This in turn makes it possible to suppress the diffusion in the width direction, and enables the absorber to smoothly deform in an oblique direction along the first linear pressed parts and the second linear pressed parts and to smoothly follow the movement of the body when the absorber is twisted. 
     (Appendix 6) 
     An embodiment of Appendix 6 provides the absorbent article described in Appendix 4 or 5 where the groove width of the compressed grooves is greater than the groove width of the linear pressed parts. 
     In the embodiment of Appendix 6, the groove width of the compressed grooves is made greater than the groove width of the linear pressed parts so that the body fluid reaching the compressed grooves flows along the compressed grooves instead of the core press disposed adjacent to the outer side of the compressed grooves and the diffusion of the body fluid to the outside of the compressed grooves is suppressed. 
     (Appendix 7) 
     An embodiment of Appendix 7 provides the absorbent article described in any one of Appendices 1-6 where front and rear compressed grooves are formed along the width direction of the absorbent article in front of and behind the area corresponding to the body fluid discharge part of the wearer. 
     In the embodiment of Appendix 7, the front and rear compressed grooves are formed along the width direction of the absorbent article in front of and behind the area corresponding to the body fluid discharge part of the wearer to suppress the diffusion of the body fluid in the longitudinal direction and improve the effect of preventing leakage from the front and rear ends of the absorber. Also, the front and rear compressed grooves function as bending guide lines that guide the absorber to deform along the front and rear round portions of the body. 
     (Appendix 8) 
     An embodiment of Appendix 8 provides the absorbent article described in any one of Appendices 1-7 where the core press is omitted in positions where the core press overlaps the compressed grooves and in a vicinity of the compressed grooves such that a non-pressed part with a predetermined width is formed around each of the compressed grooves. 
     In the embodiment of Appendix  8 , the non-pressed part is formed around each compressed groove so that the body fluid diffused along the core press is temporarily retained in the non-pressed part before reaching the compressed groove. This in turn makes it possible to lower the diffusion rate of the body fluid and enables the body fluid to smoothly diffuse along the compressed groove. 
     The present application is based on and claims priority to Japanese Patent Application No. 2018-038352 filed on Mar. 5, 2018, the entire contents of which are hereby incorporated herein by reference. 
     EXPLANATION OF REFERENCE NUMERALS 
       1  . . . sanitary napkin,  2  . . . back-side sheet,  3  . . . upper-side sheet,  4  . . . absorber,  5  . . . enveloping sheet,  7  . . . side nonwoven fabric,  10  . . . core press,  11  . . . linear pressed part,  11   a  . . . first linear pressed part,  11   b  . . . second linear pressed part,  12  . . . compressed groove,  12   a  . . . longitudinal compressed groove,  12   b  lateral compressed groove,  13  . . . compressed groove,  14  . . . non-pressed part,  15  . . . high absorption part,  16  . . . central pressed part