TWI756493B - Absorbers and absorbent articles - Google Patents

Abstract

The absorber (4) of the present invention includes a fiber block (11) containing synthetic fibers (fibers 11F) and water-absorbent fibers (fibers 12F), and a plurality of fiber blocks (11) or each other or fiber blocks (11) and water-absorbent fibers (fibers 12F) are intertwined. The content mass ratio (fiber mass ratio) of the fiber lumps (11) to the water-absorbing fibers (fibers 12F) is smaller than the non-skin-opposing surface side (the surface sheet (2) side) of the absorber (4) side (back sheet (3) side). The fiber block (11) has a main body (110) divided by two opposing basic planes (111) and a skeleton plane (112) intersecting with the two basic planes (111).

Description

Absorbers and absorbent articles

The present invention relates to an absorbent which is used in direct or indirect contact with the skin and is preferably used as an absorbent for absorbent articles.

Generally speaking, absorbent articles such as disposable diapers and menstrual sanitary napkins include a front sheet disposed at a position relatively close to the wearer's skin, a back sheet disposed at a position relatively far from the wearer's skin, and Absorber between two sheets. Typically, the absorber is mainly composed of water-absorbent fibers such as wood pulp in many cases, and further contains water-absorbent polymer particles. Regarding the absorber used for an absorbent article, improvement of each characteristic, such as a softness|flexibility (cushioning property), a compression recovery property, and a shape retention property, is a big subject.

As an improvement technique of an absorber, for example, Patent Document 1 describes an absorber comprising a nonwoven sheet containing thermally fusible fibers and previously bonding fibers to give a three-dimensional structure, and water-absorbing fibers. The three-dimensionally structured non-woven fabric sheet is produced by pulverizing the non-woven fabric into fine pieces using a pulverizing method such as a chopper method. Due to the production method, the non-woven fabric has an indeterminate shape as described in FIGS. 1 and 3 of the document, and is not substantially Has a portion that is regarded as a plane. In Patent Document 1, as a preferable form of the absorber described in the document, one obtained by thermally fusing nonwoven fabric sheets to each other is described. According to the absorber described in Patent Document 1, since the non-woven fabric sheet has a three-dimensional structure, voids are formed in the absorber, and the recovery property when absorbing moisture is improved, and as a result, the water absorption performance is improved.

In addition, Patent Document 2 describes that it has relatively dense fine fiber cores And the microfiber web of fibers or fiber bundles extending outward from the core, and it is described that the microfiber web mixed with wood pulp or water-absorbing polymer particles can be used as an absorbent article. Use an absorber. This microfiber web is produced by tearing or peeling a raw material sheet such as a nonwoven fabric, and like the nonwoven fabric sheet described in Patent Document 1, it has an indeterminate shape and does not substantially have a portion that is regarded as a plane.

Moreover, in Patent Document 3, it is described that when the absorber contains a water-absorbent polymer, when the absorber absorbs liquid and swells, in order to solve the problem of the front sheet and the back sheet disposed above and below the absorber In order to prevent the swelling of the water-absorbent polymer due to the sealing of the material, a buffer layer with high compression/compression recovery and liquid permeability is interposed between the front sheet and the absorber, and it is also described that the buffer layer The layer is constituted as an aggregate of fine sheets of nonwoven fabric. In addition, it is described that the thickness of the buffer layer is 10 mm to 40 mm. In Patent Document 3, there is no specific description about the shape or the like of the fine sheet of the nonwoven fabric used for the buffer layer.

prior art literature Patent Literature

Patent Document 1: US Patent Application Publication No. 2010/0174259 Specification

Patent Document 2: Specification of US Patent No. 4813948

Patent Document 3: Japanese Patent Laid-Open No. 2003-52750

The absorption system of the present invention is used in direct or indirect contact with the skin, and has a skin-facing surface disposed relatively close to the user's skin during use, and a non-skin-facing surface disposed relatively far away from the user's skin . The present invention includes fiber blocks comprising synthetic fibers and water-absorbing fibers, and a plurality of the fiber blocks or the fiber blocks and the water-absorbing fibers are intertwined with each other. superior The mass ratio of the fiber mass relative to the water-absorbent fiber is smaller on the skin-facing surface side than on the non-skin-facing surface side.

Moreover, this invention is an absorbent article provided with the absorber of the said invention.

1: Menstrual pads

2: front sheet

3: back sheet

4: Absorber

4A: Absorber

5: Absorbent body

5W: Wings

6: Side Sheets

10bs: Sheet

11: Fiber Blocks

11A: Fiber Blocks

11B: Fiber Blocks

11F: Fiber

11P: Parts rich in fiber blocks

12F: Fiber

12P: The part rich in absorbent fibers

13: Water Absorbent Polymer

40: Absorbent core

41: Chip material

100: Assay table

100a: Bevel

101: Acrylic Sheet

110: body part

111: Fundamentals

111a: Short side

111b: Long side

112: Skeleton Surface

113: Extend the fiber part

113S: Extend the fiber bundle

A: Front area

B: Vertical central area

C: rear area

D1: 1st direction

D2: 2nd direction

L1: length

L1a: Interval

L2: length

L2a: Interval

S: Measurement object

T: Thickness

X: Portrait

Y: horizontal

Z: thickness direction

θ: angle

Fig. 1 is a plan view schematically showing a part of the skin-opposing surface side (surface sheet side) of an example of a menstrual sanitary napkin which is an embodiment of the absorbent article of the present invention.

Fig. 2 is a cross-sectional view schematically showing a section taken along the line I-I of Fig. 1 .

Fig. 3 is a cross-sectional view showing only the absorber shown in Fig. 2 in an enlarged manner.

Fig. 4 is a view (cross-sectional view) corresponding to Fig. 3 of another embodiment of the absorber of the present invention.

Fig. 5(a) and Fig. 5(b) are schematic perspective views of the main body in the fiber block of the present invention, respectively.

Fig. 6 is an explanatory diagram of a method for producing the fiber mass of the present invention.

Fig. 7(a) is an electron microscope photograph of an example of the fiber mass of the present invention (observation magnification: 25 times), and Fig. 7(b) is a schematic diagram showing the fiber mass of the electron micrograph as the absorber shown in Fig. 2. Diagram of the fibrous mass contained.

Fig. 8 is an explanatory diagram of a method for measuring the surface diffusion area.

The synthetic fiber aggregates contained in the absorbers described in Patent Documents 1 and 2 are indefinitely shaped as described above, and their shapes and sizes are completely inconsistent. Therefore, when mixed with wood pulp or the like, it may be difficult to obtain a uniform mixture of the two. There is a risk that the desired effect will not be obtained. Furthermore, it is presumed that the synthetic fiber aggregate system disclosed in these documents is produced by pulverizing a nonwoven fabric mainly composed of synthetic fibers into a fine sheet, or by tearing or peeling it, so that the surface becomes irregularly rough. In an absorbent body containing a plurality of such synthetic fiber aggregates with rough surfaces, a plurality of The synthetic fiber aggregates are entangled with each other with a relatively strong binding force over the entire surface, and as a result, the freedom of movement of each synthetic fiber aggregate is significantly restricted. Therefore, it is difficult to form a gap through which bodily fluids pass, and the fluid absorption property is poor. In addition, as shown in the preferred form of the absorber described in Patent Document 1, when all synthetic fiber aggregates contained in the absorber are thermally fused to each other, their own motions are restricted, and as a result, the absorber as a whole has a problem. There is a possibility that the hardness will increase and the liquid absorbability will further decrease.

In addition, when the synthetic fiber aggregates described in Patent Documents 1 and 2 are incorporated into the absorber, the inter-fiber distance between the constituent fibers becomes longer than that in a normal absorber not incorporating such a fiber aggregate. Therefore, there exists a possibility that the ease (liquid introduction property) of the introduction|transduction of the liquid existing on the absorber surface into the inside of an absorber may fall. Furthermore, when the buffer layer containing the synthetic fiber aggregate which has a considerable thickness as described in patent document 3 is arrange|positioned on an absorber, the problem of the said liquid absorption becomes more serious.

Therefore, the present invention is directed to providing an absorbent body with high cushioning properties, not easily twisted, excellent in liquid introduction properties, and improved wearing feeling when applied to an absorbent article, and an absorbent article using the absorbent body.

Hereinafter, the absorber of the present invention and the absorbent article of the present invention provided with the same will be described with reference to the drawings based on preferred embodiments thereof. 1 and 2 show a menstrual sanitary napkin 1 (hereinafter also referred to as "sanitary napkin 1") as one embodiment of the absorbent article of the present invention. The sanitary napkin 1 includes: an absorber 4 that absorbs and retains body fluids; a liquid-permeable surface sheet 2 that is disposed on the skin-opposite side of the absorber 4 so as to be in contact with the wearer's skin; and a liquid-impermeable surface sheet 2 The back surface sheet 3 is arrange|positioned at the non-skin facing surface side of this absorber 4. As shown in FIG. 1 , the sanitary napkin 1 has a longitudinal direction X corresponding to the front and rear directions of the wearer and extending from the wearer's abdomen to the back through the crotch portion, and a transverse direction Y perpendicular to it, and is divided in the longitudinal direction X. for 3 The area, that is, the longitudinal central area B including the excretion part opposing part (excretion point) opposite to the excretory part such as the wearer's vulva, is arranged on the wearer's ventral side (front side) rather than the excretion part opposing part. ) The front area A, and the rear area C which is arranged on the back side (rear side) of the wearer rather than the excretion part opposing part.

In this specification, the "skin-facing side" refers to the side of the absorbent article or its constituent members (such as the absorber 4) that faces the wearer's skin when the absorbent article is worn, that is, the side that is relatively close to the wearer's skin, The "non-skin-facing surface" refers to the surface of the absorbent article or its constituent members that faces the side opposite to the skin side when the absorbent article is worn, that is, the side relatively far from the wearer's skin. In addition, the term "wearing" here refers to a state in which a normally appropriate wearing position, that is, an accurate wearing position of the absorbent article is maintained.

As shown in FIG. 1 , the sanitary napkin 1 has an absorbent body 5 having a long shape in the longitudinal direction X, and each of the two sides along the longitudinal direction X of the longitudinal central region B in the absorbent body 5 is extended in the transverse direction Y. A pair of wing portions 5W and 5W extend from the outside. The absorbent body 5 is a part that constitutes the main body of the sanitary napkin 1, and includes the above-mentioned front sheet 2, back sheet 3, and absorber 4, and is divided into a front area A, a longitudinal center area B, and a rear area C in the longitudinal direction X. 3 areas.

Furthermore, the longitudinal center region in the absorbent article of the present invention refers to the longitudinal direction (the longitudinal direction, the X direction in the figure) of the absorbent article when the absorbent article has wing portions such as sanitary napkins. The area with the wings on the top, taking the sanitary napkin 1 as an example, is the area sandwiched between the root of one wing 5W along the longitudinal direction X and the root of the other wing 5W along the longitudinal X. Moreover, the longitudinal center area|region in the absorbent article which does not have a wing part is an intermediate area when the absorbent article is divided into three equal parts in the longitudinal direction.

In the sanitary napkin 1 , the absorber 4 includes a liquid-absorbent absorptive core 40 and a liquid-permeable core wrapping material 41 covering the outer surface of the absorptive core 40 . absorbent core 40 is the same as the absorptive body 5, and has a long shape in the longitudinal direction X in the plan view as shown in FIG. The width direction is consistent with the lateral direction Y of the sanitary napkin 1 . The absorptive core 40 and the core wrapping material 41 may be joined by an adhesive such as a hot-melt adhesive.

In this way, the absorber 4, which is one embodiment of the absorber of the present invention, is incorporated into an absorbent article such as the sanitary napkin 1 to indirectly contact the human skin, that is, through the surface sheet 2 and other members. The user is indirectly in contact with the skin and has a skin-opposing surface (opposite surface to the front sheet 2 ) disposed at a position relatively close to the skin of the user (the wearer of the sanitary napkin 1 ) during use, and It is arranged on the non-skin facing surface (the facing surface of the back sheet 3) that is relatively far away from the user's skin, and further has a longitudinal direction X corresponding to the front and rear directions of the wearer of the sanitary napkin 1 and a transverse direction orthogonal to it. Y is divided into three areas in the vertical direction X, namely, the front area A, the vertical center area B, and the rear area C. In addition, the absorber 4 may be used in a form of directly contacting the skin without interposing a member such as a separator, in addition to the form in which the absorber 4 is used in direct contact with the skin.

In the sanitary napkin 1, the core wrapping sheet 41 is a continuous sheet having a width of not less than 2 times and not more than 3 times the length of the transverse direction Y of the absorbent core 40, and as shown in FIG. 2, the absorbent core is covered. The entire area of the skin-facing surface of the body 40 extends from the two side edges of the absorptive core 40 along the longitudinal direction X to the outside of the lateral direction Y, and the extended portion is rolled under the absorptive core 40 to cover the absorbent core 40. The whole area of the non-skin facing surface of the core 40 . Furthermore, in the present invention, the core wrapping material may not be such a single sheet, and may include, for example, one skin-side core wrapping sheet covering the skin-opposing surface of the absorptive core 40, and the skin-side core wrapping sheet. The core wrapping sheet separately coats the non-skin-side sheet wrapping sheet of the absorptive core 40 and the two sheets of the non-skin-side core wrapping sheet.

As shown in FIG. 2 , the surface sheet 2 covers the entire area of the skin-facing surface of the absorber 4 . On the other hand, the back sheet 3 covers the entire area of the non-skin facing surface of the absorber 4, and self-absorbs Both side edges of the body 4 along the longitudinal direction X extend outward in the lateral direction Y, and form side flaps together with the side sheets 6 described below. The above-mentioned side flaps are the parts of the sanitary napkin 1 including members extending outward in the lateral direction Y from the absorber 4 . The back sheet 3 and the side sheets 6 are joined to each other by known joining means such as adhesive, heat sealing, ultrasonic sealing, etc. in the extending portions from both side edges of the absorber 4 along the longitudinal direction X. Each of the surface sheet 2 and the back sheet 3 and the absorber 4 may be joined by an adhesive. As the surface sheet 2 and the back sheet 3, various sheets conventionally used for absorbent articles such as menstrual napkins can be used without particular limitation. For example, as the surface sheet 2, a nonwoven fabric of a single-layer or multi-layer structure, an apertured film, or the like can be used. As the back sheet 3, a moisture-permeable resin film or the like can be used.

As shown in FIG. 1 , the side flaps extend substantially outward in the longitudinal direction Y in the longitudinal central region B, whereby a pair of wing flaps 5W and 5W are extended on the left and right sides along the longitudinal direction X of the absorptive body 5 . The wing portion 5W has a substantially trapezoidal shape in which the lower bottom (side longer than the upper bottom) is located on the side of the absorbent body 5 in a plan view as shown in FIG. The wing portion 5W is fixed to a wing portion adhesive portion (not shown) of clothes worn such as shorts. The wing portion 5W is used by being folded back to the non-skin-facing surface (outer surface) side of the crotch portion of the clothes worn such as shorts. The said wing part adhesive part is covered with the release sheet (not shown) containing film, nonwoven fabric, paper, etc. before the use. In addition, the skin-facing surface of the absorbent body 5, that is, the skin-facing surface of the front sheet 2, is placed on both sides along the longitudinal direction X, so as to overlap with the left and right sides of the absorber 4 along the longitudinal direction X when viewed from above. In this way, a pair of side sheets 6 and 6 are arranged over substantially the entire length of the longitudinal direction X of the absorbent body 5 . The pair of side sheets 6 and 6 are respectively joined to other members such as the front sheet 2 by a well-known joining means such as an adhesive on a joining line not shown extending in the longitudinal direction X, respectively.

As one of the main characteristic parts of the sanitary napkin 1, the absorber 4, especially the absorptive core 40 which comprises the main body of the absorber 4 is mentioned. As shown in FIG. 2 , the absorptive core 40 further includes fibers including fibers (synthetic fibers) 11F in addition to water-absorbing fibers (fibers 12F). Aspects of block 11 are characterized. In the absorptive core 40, a plurality of water-absorbing fibers (fibers 12F) are not aggregated but exist independently, and can be taken out one by one from the absorptive core 40. In this state, the fiber mass 11 is a plurality of fibers. The fiber aggregate that 11F is intentionally aggregated into a block and integrated can exist in the absorptive core 40 in a state where the form as the fiber aggregate is always maintained. The fiber mass 11 mainly contributes to improving the softness, cushioning, compression recovery, shape retention, etc. of the absorbent core 40 . On the other hand, the water-absorbent fibers (fibers 12F) mainly contribute to the improvement of the liquid absorbency, shape retention, and the like of the absorbent core 40 . In addition, the absorptive core 40 can also be called the absorber 4 itself substantially, and the following description about the absorptive core 40 can be suitably used as the description of the absorber 4 unless otherwise specified. That is, the present invention includes the case where the absorber does not contain a core sheet and is formed of only the absorptive core, and in this case, the absorber and the absorptive core have the same meaning.

In this specification, the term "fiber mass" refers to a fiber aggregate in which a plurality of fibers are integrated into one. As a form of a fiber block, the sheet divided|segmented from the synthetic fiber sheet which has a certain size is mentioned, for example. It is particularly preferable to select a non-woven fabric as the synthetic fiber sheet, and select a non-woven fabric sheet cut out from the non-woven fabric in a specific size and shape as the fiber mass.

Thus, the sheet-like fiber block, which is a preferred embodiment of the fiber block of the present invention, is not constituted by agglomerating a plurality of fibers to form the sheet, but is formed by a fiber sheet having a size larger than that of the sheet (more It is preferably manufactured by cutting non-woven fabrics (refer to FIG. 6 ). The plurality of fiber blocks contained in the absorber of the present invention is a plurality of sheet-like fiber blocks having higher formability than those produced by the prior art such as Patent Documents 1 and 2.

Moreover, in the absorptive core 40, a plurality of fiber blocks 11 or fiber blocks 11 and water-absorbing fibers (fibers 12F) are intertwined with each other. In the absorptive core 40 of the present embodiment, the plurality of fiber blocks 11 are connected to the constituent fibers (fibers 11F, absorbent fibers, etc.) in the absorptive core 40. (fibers 12F)) are intertwined and bonded to form one continuous fiber mass. Moreover, a plurality of fiber blocks 11 may be intertwined with each other, and the fiber blocks 11 and the water-absorbing fibers (fibers 12F) may be intertwined and coupled. Furthermore, usually a plurality of water-absorbing fibers (fibers 12F) are also intertwined with each other. At least a part of the plurality of fiber blocks 11 contained in the absorbent core 40 is intertwined with other fiber blocks 11 or absorbent fibers (fibers 12F). In the absorbent core 40, all of the plurality of fiber blocks 11 contained therein may be intertwined with each other to form one continuous fiber block body, and there may be a case where a plurality of continuous fiber block bodies are mixed in a state where they are not bonded to each other. situation of existence.

The fiber mass 11 is excellent in flexibility and the like. In the absorptive core 40 of the present invention, in addition to containing such fiber blocks 11, the fiber blocks 11 or the fiber blocks 11 and the absorbent fibers (fibers 12F) are also bonded by mutual entanglement, so the absorptive core The body 40 is more responsive to external force, and has excellent flexibility, cushioning properties, and compression recovery properties. For example, when the absorbent core 40 of the present invention is incorporated into an absorbent article, it can be flexibly deformed against external forces (such as the body pressure of the wearer of the absorbent article) received from various directions, so that the absorbent core 40 can be flexibly deformed. Sexual articles adhere well to the wearer's body. Such excellent deformation-recovery characteristics of the absorbent core 40 can be exhibited not only when the absorbent core 40 is compressed, but also when twisted. That is, the absorbent core 40 incorporated in the sanitary napkin 1 is arranged in a state of being sandwiched between the two legs of the wearer when the sanitary napkin 1 is worn, so that the absorbent core 4 may be caused by the walking action of the wearer. In the case of twisting around the imaginary axis of rotation extending along the longitudinal direction X due to the movement of the two legs, even in this case, since the absorbent core 40 has high deformation-recovery characteristics, it is not suitable for promoting the The twisting external force of the leg is easily deformed and returned, so it is not easily twisted, and the sanitary napkin 1 can be provided with high conformability to the wearer's body.

In the absorptive core 40, the fiber blocks 11 or the fiber blocks 11 and the water-absorbing fibers (fibers 12F) are intertwined. In this case, the "intertwining" of the fiber blocks 11 and the like includes the following forms. A.

Form A: The form in which the fiber blocks 11 and the like are not fused, but combined by the entanglement of the constituent fibers (fibers 11F) of the fiber blocks 11 .

Form B: In the natural state of the absorptive core 40 (the state in which no external force is applied), the fiber blocks 11 and the like are not bonded to each other, but in the state where an external force is applied to the absorptive core 40, the fiber blocks 11 and the like can be A form in which constituent fibers (fibers 11F) are intertwined with each other. Here, "the state in which an external force is applied to the absorptive core 40" means, for example, a state in which a deforming force is applied to the absorptive core 40 during wearing of an absorbent article to which the absorptive core 40 is applied.

In this way, in the absorbent core 40, the fiber blocks 11 are combined by the other fiber blocks 11 or the absorbent fibers (fibers 12F) and the fibers intertwined with each other as in Form A, that is, "intertwined", and also in Form B. Generally, it exists in a state in which it can be combined with other fiber blocks 11 or absorbent fibers (fibers 12F) by intertwining, and the combination by the intertwining of fibers is to more effectively express the effect of the above-mentioned absorbent core 40. Important point. However, in terms of shape retention, it is preferred that the absorbent core has the "interlacing" of Form A.

It is not necessary that all the bonding modes through the fiber blocks 11 in the absorbent core 40 are "interlacing", and a part of the absorbent core 40 may include other bonding modes other than interlacing, such as bonding with an adhesive.

However, for example, the remainder after the "fusion through the fiber mass 11" formed in the absorbent core 40 as a result of being integrated with other members of the absorbent article such as known leak prevention grooves is removed from the absorbent core 40. In part, that is, in the absorbent core 40 itself, it is preferable that the bonding of the fiber blocks 11 or the bonding of the fiber blocks 11 and the absorbent fibers (fibers 12F) is performed only by "interlacing of fibers".

From the viewpoint of more surely expressing the effect of the above-mentioned absorbent core 40, In other words, the total number of the "fiber blocks 11 combined by intertwining" in the form A and the "fiber blocks 11 in a state that can be intertwined" in the form B is higher than the total number of the fiber blocks 11 in the absorbent core 40. It is preferably at least half, more preferably at least 70%, and still more preferably at least 80%.

From the same viewpoint, it is preferable that the number of the fiber lumps 11 having the "interlacing" of the form A is 70% or more of the total number of the fiber lumps 11 having a joint with other fiber lumps 11 or water-absorbing fibers (fibers 12F). , preferably more than 80%.

The sanitary napkin 1 is characterized not only in containing the fiber mass 11 but also in the arrangement of the fiber materials (the fiber mass 11 and the absorbent fibers (fibers 12F)) in the absorptive core 40 . That is, in the absorptive core 40, as shown in FIG.2 and FIG.3, the content mass ratio (henceforth "fiber lump ratio") of the fiber lump 11 with respect to the water-absorptive fiber (fiber 12F) is skin-facing The surface side (surface sheet 2 side) is smaller than the non-skin opposing surface side (back surface sheet 3 side). That is, in the absorptive core 40, the water absorbent fibers (fibers 12F) are concentrated on the skin-opposing surface side, and the fiber lumps 11 (synthetic fibers (fibers 11F)) are concentrated on the non-skin-opposing surface side.

In this way, the side of the absorbent core 40 that initially receives the bodily fluids excreted by the wearer of the sanitary napkin 1, that is, the skin-facing side of the absorbent core 40, is set to the side with a relatively low fiber mass ratio (including the fiber mass). ratio of 0 mass %), in other words, the "water-absorbent fiber-rich portion 12P" (see FIG. 3 ) that contains a larger amount of water-absorbent fibers (fibers 12F) than other portions of the absorptive core 40 (see FIG. 3 ), the absorptive core The liquid introduction force (capillary force) of the skin-opposing surface of 40 is improved, and the liquid absorbency of the absorptive core 40 is improved. On the other hand, the non-skin-facing surface side of the absorptive core 40 becomes a site where the ratio of fiber lumps is relatively high (including the case where no water-absorbent fibers are present but only fiber lumps), in other words, compared with other parts of the absorptive core 40 . The "fiber-mass-rich portion 11P" (refer to FIG. 3 ) in the portion containing a larger amount of the fiber mass 11 , so that the absorbent core 40 can sufficiently exert the effect of improving the cushioning property and the resistance to twisting, etc., mainly by the fiber mass 11 the resulting effect. Yu Fu In the site 11P containing the fiber lumps, it is preferable that the fiber lumps 11 are uniformly distributed throughout the site 11P at a high density from the viewpoint of making the site 11P more reliably exhibit the desired effect.

The aforementioned fiber mass ratio, that is, the content mass ratio of the fiber mass 11 with respect to the water-absorbent fibers (fibers 12F) was calculated as follows. For the measurement target site (eg, absorption) in the thickness direction of the absorber 4 (absorptive core 40 ), that is, in the direction perpendicular to the skin-facing surface or the non-skin-facing surface of the absorber 4 (absorptive core 40 ) body 4), measure the content (mass) of each of the fiber lumps 11 and the water-absorbent fibers (fibers 12F) present in the measurement target site, and divide the thus-measured content of the fiber lumps 11 by the water absorption The content of sexual fibers (fiber 12F) is expressed as a 100-point rate, and the obtained value is the fiber mass ratio of the measurement target site.

From the viewpoint of rapidly introducing bodily fluids into the inside of the absorptive core 40, the ratio of the fiber mass in the skin-facing surface side of the absorptive core 40, that is, in the portion 12P rich in water-absorbent fibers, is preferably 140 mass % or less, more preferably 70 mass % or less, still more preferably 30 mass % or less. The lower limit value of the fiber lump ratio in the water-absorbent fiber-rich portion 12P is preferably 10% by mass, more preferably 5% by mass, and still more preferably 0% by mass.

The non-skin-opposing surface side of the absorptive core 40, that is, the fiber mass ratio in the portion 11P rich in fiber mass is premised on being larger than the fiber mass ratio on the skin-opposing surface side, preferably 70% by mass or more, and more Preferably it is 140 mass % or more, More preferably, it is 170 mass % or more. In addition, there is no particular limitation on the upper limit of the fiber mass ratio on the non-skin-opposing surface side of the absorbent core 40, and the content of the water-absorbing fibers (fiber 12F) on the non-skin-opposing surface side may be 0. quality%. In this case, since the denominator in the calculation formula becomes zero, the fiber mass ratio becomes infinite numerically. In this case, in this specification, instead of the fiber mass ratio, it may be expressed as "only exists. "fiber lump", or the following fiber lump occupancy rate is 100% by mass.

As described above, the sanitary napkin 1 has water-absorbing fibers (fibers) in the absorbent core 40 12F) It is characteristic that the segregation exists on the skin-opposing surface side, and the fiber mass 11 (synthetic fiber (fiber 11F)) segregation exists on the non-skin-opposing surface side. The ratio of the mass of the fiber mass 11 to the total mass of the fiber mass 11 and the water-absorbent fibers (fibers 12F) can also be used as an index showing the characteristics related to the distribution of the fiber mass 11 (hereinafter also referred to as "fiber mass"). block occupancy") in place of the above-mentioned fiber block ratio.

The fiber mass occupancy rate was calculated as follows. For the measurement target site (eg, absorption) in the thickness direction of the absorber 4 (absorptive core 40 ), that is, in the direction perpendicular to the skin-facing surface or the non-skin-facing surface of the absorber 4 (absorptive core 40 ) body 4), the content (mass) of each of the fiber lumps 11 and the water-absorbent fibers (fibers 12F) present in the measurement target portion is measured, and the content mass of the fiber lumps 11 thus measured is divided by The total value of the content of the water-absorbent fibers (fibers 12F) and the fiber mass 11 is expressed as a 100-point rate, and the obtained value is the fiber mass occupancy rate of the measurement target site.

From the viewpoint of exhibiting the above-mentioned effects more reliably, the fiber mass occupancy rate in each part of the absorptive core 40 is preferably set as follows on the premise that the non-skin-opposing surface side is larger than the skin-opposing surface side. .

The skin-facing surface side of the absorptive core 40, that is, the fiber mass occupancy rate in the portion 12P rich in water-absorbent fibers is preferably 60% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass the following. In addition, the lower limit value of the fiber mass occupancy rate in the water-absorbent fiber-rich portion 12P is preferably 10% by mass, more preferably 5% by mass, and still more preferably 0% by mass.

The non-skin-facing surface side of the absorptive core 40, that is, the fiber mass occupancy rate in the fiber mass-rich portion 11P is preferably 50 mass % or more, more preferably 60 mass % or more, and still more preferably 70 mass % above, and preferably 100 mass % or less, more preferably 95 mass % or less, still more preferably 85 mass % or less.

The difference between the fiber mass occupancy rate of the fiber mass-rich site 11P and the fiber mass occupancy ratio of the water-absorbent fiber-rich site 12P is preferably 15% by mass or more, more preferably 50% by mass when the latter is subtracted from the former. mass % or more, more preferably 80 mass % or more.

Furthermore, the range of the "fiber mass occupancy rate" in the above-mentioned fiber mass-rich site 11P and the water-absorbent fiber-rich site 12P, and the "fiber mass-rich site 11P" and the water-absorbent fiber-rich site 12P " When the absorbent core 40 is integral as a whole, the absorbent core 40 is divided into two equal parts in the thickness direction, and the skin-facing side is used as the fiber-rich side. The part 11P of the block is used as the part 12P rich in water-absorbing fibers on the non-skin facing side.

Here, "the absorptive core is integrally formed as a whole" means that the absorptive core is integrally formed, and the structure of a plurality of absorptive core layers formed by lamination is excluded. The latter is constituted so that one absorbent core layer and another absorbent core layer can be separated, and the two layers are not inseparable and not integrated. As a specific example of the form in which the absorptive core body is integral as a whole, the form in which all the forming materials (fiber block 11, water-absorbing fiber (fiber 12F)) of the absorptive core body 40 are piled up at one time is mentioned. Although the absorptive core 40 in each of the absorber 4 shown in FIG. 3 and the absorber 4A shown in FIG. 4 described below has two positions (rich in water absorption) in which the fiber block occupancy and fiber block ratio are different from each other The fiber part 12P and the fiber block-rich part 11P), but at the interface between these two parts 12P and 11P, the absorbent fibers (fibers 12F) and the constituent fibers (fibers 11F) are intertwined with each other, so that the entire absorbent core is on unity. On the other hand, in the absorptive core 40 in the modified example of the absorber 4A described below, the absorbent fibers (fibers 12F) and the constituent fibers (fibers 11F) are substantially at the interface between the two parts 12P and 11P divided into layers. It is not intertwined, and the absorbent core is not integrated as a whole.

In the present invention, it is preferable that the portion 12P rich in water-absorbing fibers is composed of only water-absorbing fibers The form of fiber (fiber 12F) is excellent in that the effect of the fiber block 11 can be enhanced by the entire absorptive core 40 if the fiber block 11 is present in the portion 12P rich in water-absorbent fibers. . In particular, if the fiber mass 11 and the water-absorbent fiber (fiber 12F) are intertwined or intertwined in the water-absorbent fiber-rich portion 12P where the fiber mass 11 and the water-absorbent fiber (fiber 12F) are mixed, It is preferable that the absorbent fibers (fibers 12F) absorb body fluids such as menstrual blood at the absorbent fiber-rich site 12P first, and then supply the body fluid to the space within the fiber-rich site 11P. Furthermore, it is preferable that the fiber mass 11 and the water-absorbing fiber (fiber 12F) are intertwined in the portion 11P rich in the fiber mass to more easily exhibit the above-described effect.

In the absorptive core 40, as shown in FIG. 3, the fiber block occupancy rate and the fiber block ratio go from the skin-opposing surface side (surface sheet 2 side) to the non-skin-opposing surface side (back surface sheet 3 side) ) and gradually increase. In other words, in the absorptive core 40, the water-absorptive fibers (fibers 12F) gradually decrease from the skin-opposing surface side toward the non-skin-opposing surface side. That is, in the thickness direction of the absorptive core 40, on the skin-facing surface of the absorptive core 40 and its vicinity, the fiber lumps 11 do not exist, or the fiber lump occupancy rate in the absorptive core 40 is the lowest, the lowest The fiber block ratio exists in the absorptive core 40 with the highest fiber block occupancy rate and the highest fiber block ratio in the non-skin facing surface of the absorptive core 40 and its vicinity.

The arrangement of the fiber materials (fiber blocks 11, water-absorbing fibers (fibers 12F)) in the absorbent core 40 is not limited to the arrangement shown in FIG. The arrangement in which one surface side in the thickness direction of the core body 40 is gradually changed toward the other surface side can be appropriately changed within a range that does not deviate from the technical idea of the present invention. FIG. 4 shows a view corresponding to FIG. 3 of an absorber 4A which is another embodiment of the absorber of the present invention. In addition, about the absorber 4A, the structure part different from the said absorber 4 is demonstrated mainly, and the same code|symbol is attached|subjected to the same structure part, and description is abbreviate|omitted. Appropriate application of the relevant In the description of the absorber 4 (absorptive core 40).

In the absorber 4A shown in FIG. 4 , the absorber 4A is divided into two parts (the part 12P rich in water-absorbing fibers, the part 12P rich in water-absorbing fibers, the part 12P rich in water-absorbing fibers, the part 12P, the part rich in water-absorbing fibers, the part 12P, the part 12P, the part 12P, the part 12P, the part 12P, the part 12P, the part 12P, the part 12P, the part rich in water-absorbing fibers, the part 4A shown in FIG. 4 ). Parts rich in fibrous mass 11P). Moreover, among the two parts, the fiber mass occupancy rate and the fiber mass ratio of the site 12P rich in absorbent fibers on the skin-opposing side and the fiber mass-rich site 11P on the non-skin-opposing surface side can be found in The thickness direction of the absorber 4A is not fixed. Regarding each of the parts 11P and 12P, the difference in the fiber mass occupancy rate between the skin-opposing surface-side part and the non-skin-opposing surface-side part when divided into two equal parts in the thickness direction is preferably 30 mass % or less, more preferably It is 10 mass % or less. In the absorber 4A, it is preferable that the fiber block occupancy rate and the fiber block ratio vary greatly at the interface between the water-absorbent fiber-rich site 12P and the fiber block-rich site 11P. The interface between the two parts is the center in the thickness direction of the absorber 4A in the form shown in FIG. 4 , that is, the absorber 4A is divided into two parts in the thickness direction, the part 12P rich in water absorbent fibers and the part rich in fiber blocks. Part 11P, but the position of the interface can be set appropriately, and the thicknesses of the two parts can also be different from each other.

In the case where the absorber 4A shown in FIG. 4 is divided into layers 12P rich in absorbent fibers and 11P rich in fiber lumps in the absorbent core 40, the absorbent fiber rich part is 12P is preferably a position that spans 20-80% of the thickness of the absorbent core 40 from the skin of the absorbent core 40 facing the inner side of the absorbent core 40 in the thickness direction, more preferably spans the thickness 30~70% of the parts. In addition, the portion 11P rich in fiber blocks is preferably the non-skin-facing side of the absorptive core 40 facing the inner side in the thickness direction of the absorptive core 40 and 20-80% of the thickness of the absorptive core 40 part, more preferably a part spanning 30-70% of the thickness.

Moreover, like the absorber 4A shown in FIG. 4, in the absorptive core 40, it is divided into rich layers in the form of layers. In the case of the part 12P containing water absorbent fibers and the part 11P rich in fiber lumps, the thickness of each part 12P rich in water absorbent fibers and the part 11P rich in fiber lumps is preferably 0.5 mm or more, more preferably 1 mm The above, and preferably 10 mm or less, more preferably 5 mm or less, and still more preferably 4 mm or less.

The thickness of each part of the absorptive core 40 is measured by the following method. In addition, the thickness of the whole absorptive core 40 (absorber 4), the thickness of the sanitary napkin 1, etc. can also be measured according to the following method.

<Measurement method of thickness>

The absorbent core (absorber) is placed in a horizontal place without wrinkling or bending, and the measurement target portion (for example, the skin-facing side of the absorbent core or the non-skin side of the absorbent core) is cut out from the absorbent core. opposite side) as a measurement sample. Then, the thickness of the measurement sample under a load of 5 cN/cm ² was measured. Specifically, the thickness is measured using, for example, a thickness gauge PEACOCK DIAL UPRIGHT GAUGES R5-C (manufactured by OZAKI MFG.CO.LTD.). At this time, between the front end of the thickness gauge and the measurement sample, a circular or square flat plate (acrylic plate with a thickness of about 5 mm) whose size is adjusted so that the load becomes 5 cN/ ^cm2 in plan view (acrylic plate with a thickness of about 5 mm) is arranged, and the thickness is measured. . For the thickness measurement, 10 points were measured, and the average value thereof was calculated as the thickness.

In the absorber 4A, the portion 12P rich in water absorbent fibers and the portion 11P rich in the fiber mass are formed by the constituent fibers (the constituent fibers (fibers 11F) of the fiber mass 11 , the water absorbent fibers (the fibers 12F) at the interfaces thereof. ) are intertwined with each other and combined with each other. That is, at the interface between the two parts, the water-absorbent fibers (fibers 12F) of the water-absorbent fiber-rich part 12P on the skin-facing side and the fiber mass 11 ( The fibers 11F) are intertwined with each other, whereby the two parts are relatively well bonded, and the absorber 4A (absorptive core 40 ) is integrated as a whole.

Furthermore, as a modification example of the absorber 4A shown in FIG. 4 , there can be mentioned the unbonded portion 12P rich in water absorbent fibers on the skin-opposite side and the portion 11P rich in fiber blocks on the non-skin-opposite side. The form is also included in the present invention. The modification of the absorber 4A is manufactured by separately manufacturing a layer corresponding to the portion 12P rich in water-absorbent fibers and a layer corresponding to the portion 11P rich in fiber blocks separately first, and then separately manufacturing the two layers. Layers overlap. In the modified example of the absorbent body 4A obtained by this production method, there is almost no entanglement between the constituent fibers (fibers 11F) and the water-absorbent fibers (fibers 12F) at two locations, so that the absorptive core 40 does not as a whole. When integrated, it can be easily separated into a portion 12P rich in absorbent fibers and a portion 11P rich in fiber mass.

The advantages peculiar to the form in which the fiber block occupancy rate and fiber block ratio of the absorber 4 shown in FIG. 3 gradually change from one surface side to the other surface side in the thickness direction of the absorber include the following: The mixing ratio of the absorbent fibers and the fiber blocks changes smoothly in the thickness direction of the absorber, so even when an external force is applied to the absorber, it is easy to maintain the intertwined state of the intervening fiber blocks throughout the thickness direction, and it is easy to The cushioning property of the absorber is well maintained during use. Moreover, as the absorber 4A shown in FIG. 4, the advantages peculiar to the form in which the fiber mass occupancy ratio and the fiber mass ratio are different from each other in two positions in the thickness direction include the following: the skin of the absorber The opposite side and the non-skin facing side can be easily designed as independent functions.

The absorbers 4 and 4A (absorptive core 40) can be conventionally manufactured using a known fiber stacking device equipped with a rotating drum. (fibers 12F)) can be specified by appropriately adjusting the fiber stacking sequence of the fiber mass 11 or the water-absorbing fibers (fibers 12F) on the drum in the manufacturing method using the fiber stacking device.

The absorptive core 40 may contain other components other than the fiber mass 11 and the water-absorbent fibers (fibers 12F), and a water-absorbent polymer may be exemplified as the other components. Reference numeral 13 in the drawing is a water-absorbing polymer. As the water-absorbent polymer, generally, a particle-like one as shown in the figure is used, but a fibrous one may also be used. In the case of using a particulate water-absorbent polymer, the shape may be any of spherical, block, bag or indeterminate shapes. The average particle diameter of the water-absorbing polymer is preferably 10 μm or more, more preferably 100 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less. As the water-absorbing polymer, generally, a polymer or copolymer of acrylic acid or an alkali metal salt of acrylic acid can be used. Examples thereof include polyacrylic acid and salts thereof, and polymethacrylic acid and salts thereof.

In the absorptive core 40, as shown in FIG. 3, since the water-absorbent polymer 13 is contained in the skin-opposing surface side of the absorptive core 40, it is contained in the site|part 12P rich in water-absorbent fibers. In this way, the skin-opposite side of the absorptive core 40, which is particularly problematic in terms of liquid introduction properties, contains the water-absorbent polymer 13 having excellent water-absorption properties, and the skin-opposite side is rich in water-absorbent fibers. The site 12P, that is, the fiber block occupancy rate and the fiber block ratio are relatively low, and the liquid introduction property of the skin-facing surface of the absorptive core 40 can be further improved.

In the absorptive core 40, the water-absorbent polymer 13 may be contained in a portion other than the skin-opposite side (the portion 12P rich in water-absorbent fibers) of the absorptive core 40, that is, the portion rich in fiber lumps 11P . In particular, it can be said that the water-absorbent polymer 13 is actively It is basically meaningless to be contained in the non-skin-opposing surface side of the absorptive core 40 (part 11P rich in fiber lumps). In addition, if the water-absorbent polymer 13 is positively contained in the non-skin-opposing surface side (the portion 11P rich in fiber lumps) of the absorptive core 40, there is an effect of preventing the portion 11P rich in fiber lumps. There is a risk of the performance of the effect (buffering property or the effect of improving the distortion resistance, etc.). Considering the above situation, the skin-facing surface side (rich in absorbent core 40) The content of the water-absorbent polymer 13 in the part other than the part 12P of the water-based fiber, specifically, the part 11P rich in fiber lumps, is preferably less than that on the skin-opposite side, and may be zero.

The content of the water-absorbent polymer 13 in the absorbent core 40 is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 60% by mass relative to the total mass of the absorbent core 40 in the dry state % or less, more preferably 40 mass % or less.

The basis weight of the water-absorbent polymer 13 in the absorbent core 40 is preferably 10 g/m ² or more, more preferably 30 g/m ² or more, and preferably 100 g/m ² or less, more preferably 70 g/m ² the following.

As one of the main features of the absorptive core 40, the outer shape of the fiber mass 11 is mentioned. Two typical external shapes of the fiber mass 11 are shown in FIG. 5 . The fiber block 11A shown in FIG. 5( a ) has a quadrangular column shape, more specifically, a rectangular parallelepiped shape, and the fiber block 11B shown in FIG. 5( b ) has a disk shape. The fiber blocks 11A and 11B have two base planes 111 facing each other and a body plane 112 connecting the two base planes 111 in common. Both the base plane 111 and the skeleton plane 112 are considered to be substantially free of unevenness according to the grades applied when evaluating the degree of unevenness of the surface of an article mainly composed of such fibers.

The cuboid-shaped fiber block 11A shown in FIG. 5( a ) has six flat surfaces. At this time, two opposite surfaces with the largest area among the six surfaces are the base surfaces 111 , and the remaining four surfaces are the skeleton surfaces 112 respectively. The base plane 111 and the skeleton plane 112 intersect with each other, more specifically, they are orthogonal.

The disk-shaped fiber block 11B in FIG. 5( b ) has two opposite flat surfaces that are circular in plan view, and a curved peripheral surface connecting the two flat surfaces. In this case, the two flat surfaces are the basic surfaces, respectively. 111 , the peripheral surface is the skeleton surface 112 .

The fiber blocks 11A and 11B are also common in that the frame surface 112 has a quadrangular shape in plan view, more specifically, a rectangular shape.

The plurality of fiber blocks 11 contained in the absorbent core 40 are respectively as shown in FIG. 5 . The fiber blocks 11A and 11B are shown as "fixed-shaped fiber aggregates" having two opposing basic planes 111 and a skeleton plane 112 connecting the two basic planes 111. In this respect, it is related to the patent document as an amorphous fiber aggregate. The nonwoven sheets or microfiber webs described in 1 and 2 are different. In other words, when any one fiber block 11 in the absorbent core 40 is observed through perspective (for example, when observed with an electron microscope), the perspective shape of the fiber block 11 varies depending on the viewing angle. The block 11 has a plurality of perspective shapes, and the plurality of fiber blocks 11 in the absorbent core 40 respectively have a specific perspective shape having two basic planes 111 facing each other and a skeleton plane 112 connecting the two basic planes 111 as its plurality. One of the perspective shapes. The plurality of nonwoven sheets or microfiber webs contained in the absorbers described in Patent Documents 1 and 2 do not substantially have a "face" such as the base face 111 or the frame face 112, that is, have a widened portion, and have different external shapes. rather than "fixed".

In this way, if the plurality of fiber blocks 11 contained in the absorptive core 40 are "fixed-shaped fiber aggregates" formed by dividing the base plane 111 and the skeleton plane 112, it is different from the one described in Patent Documents 1 and 2. Compared with the case of the fixed fiber aggregate, the uniform dispersibility of the fiber mass 11 in the absorbent core 40 is improved. Therefore, by incorporating the fiber aggregate such as the fiber mass 11 into the absorbent core 40, stable Expected effects (improvement effects such as the softness of the absorber, cushioning properties, compression recovery properties, etc.) are exhibited. Moreover, especially in the case of the cuboid-shaped fiber block 11 as shown in Fig. 5(a), its outer surface includes 2 basic planes 111 and 6 planes of the 4 skeleton planes 112, so the same as Fig. 5(b) ), compared with the disk-shaped fiber block 11 with three outer surfaces shown in ), it can have relatively more contact opportunities with other fiber blocks 11 or water-absorbing fibers (fibers 12F), and the intertwining property is improved, and there are also Helps improve shape retention, etc.

In the fiber block 11 , it is preferable that the total area of the two basic surfaces 111 is greater than the total area of the skeleton surface 112 . That is, in the cuboid-shaped fiber block 11A of FIG. 5(a), the sum of the areas of the two basic planes 111 is larger than the sum of the areas of the four skeleton planes 112, and the In the disk-shaped fiber block 11B of 5(b), the sum of the areas of the two basic surfaces 111 is larger than the area of the skeleton surface 112 forming the peripheral surface of the disk-shaped fiber block 11B. In either of the fiber blocks 11A and 11B, the base plane 111 is the plane with the largest area among the plurality of planes of the fiber blocks 11A and 11B.

Such a fiber block 11 as a "fixed fiber aggregate" formed by dividing the two basic planes 111 and the skeleton plane 112 intersecting with the two basic planes 111 can be realized by making a manufacturing method different from that of the prior art. As shown in FIG. 6 , a preferred method for producing the fiber block 11 is to use a cutting mechanism such as a cutter to cut the raw fiber sheet 10bs (a sheet with the same composition as the fiber block 11 and a size larger than the fiber block 11 ) that becomes the raw material for shape. The shape and size of the plurality of fiber blocks 11 thus manufactured are more uniform in shape than those manufactured by the prior art such as Patent Documents 1 and 2. Fig. 6 is a diagram for explaining a method of manufacturing the cuboid-shaped fiber block 11A in Fig. 5(a) , and the broken line in Fig. 6 represents a cutting line. The absorptive core 40 is blended with a plurality of fiber blocks 11 of uniform shape and size obtained by cutting the fiber sheet in a fixed shape in this way. As described above, the raw fiber sheet 10bs is preferably a nonwoven fabric.

The cuboid-shaped fiber block 11A shown in Fig. 5(a) is obtained by aligning the raw fiber sheet 10bs in the first direction D1 and the first direction D1 intersecting (more specifically, orthogonal to) the first direction D1 as shown in Fig. 6 . It is produced by cutting to a predetermined length in the two directions D2. The two directions D1 and D2 are respectively a specific one direction in the surface direction of the sheet 10bs, and the sheet 10bs is cut along the thickness direction Z orthogonal to the surface direction. In this way, among the plurality of cuboid-shaped fiber blocks 11A obtained by cutting the raw fiber sheet 10bs into a so-called small square shape, the cut surface, ie, the sheet 10bs, is usually cut with a cutter or the like at the time of cutting the sheet 10bs. The surface that the mechanism contacts is the skeleton surface 112 , and the non-cut surface, that is, the surface that is not in contact with the cutting mechanism, is the base surface 111 . The basic surface 111 is the front and back surfaces of the sheet material 10bs (surfaces orthogonal to the thickness direction Z), and, as described above, is the surface with the largest area among the plurality of surfaces included in the fiber mass 11A.

Furthermore, the above description about the fiber block 11A is basically applicable to the disk-shaped fiber block 11B shown in FIG. 5( b ). The substantial difference from the fiber block 11A is only the cutting pattern of the raw fiber sheet 10bs. When the fiber block 11B is obtained by cutting the sheet 10bs in a fixed shape, the sheet should be cut according to the plan shape of the fiber block 11B. 10bs can be cut into a circular shape.

In addition, the outer shape of the fiber block 11 is not limited to that shown in FIG. 5 , the basic surface 111 and the skeleton surface 112 can be flat surfaces that are not curved like the surfaces 111 and 112 in FIG. 5( a ), or can be The frame surface 112 (the peripheral surface of the disk-shaped fiber block 11B) as shown in FIG. 5(b) is a curved surface. In addition, the basic surface 111 and the frame surface 112 may have the same shape and size as each other.

As described above, the two types of surfaces (the base surface 111 and the skeleton surface 112 ) possessed by the fiber block 11 ( 11A, 11B) are classified into the raw fiber sheets that are cut by a cutting mechanism such as a cutter when the fiber block 11 is produced. A cut surface (frame surface 112 ) formed by cutting the material 10bs, and a non-cut surface (basic surface 111 ) that is not in contact with the cutting mechanism, which is the surface originally possessed by the sheet material 10bs. Furthermore, depending on whether or not it is the cut surface, the skeleton surface 112 as the cut surface is characterized in that the number of fiber ends per unit area is larger than that of the base surface 111 as the non-cut surface. The term "fiber end portion" as used herein refers to the end portion in the longitudinal direction of the constituent fibers (fibers 11F) of the fiber mass 11 . Usually, fiber ends also exist in the basic plane 111 which is a non-cut surface, but since the skeleton surface 112 is a cut surface formed by cutting the raw fiber sheet 10bs, it includes the cutting surface formed by the cutting. A plurality of fiber ends constituting the cut ends of the fibers (fibers 11F) exist in the entire skeleton surface 112, that is, the number per unit area of the fiber ends is greater than that of the fiber ends per unit area of the basic plane 111. the quantity.

The fiber ends present on each surface (basic surface 111, skeleton surface 112) of the fiber block 11 are important for the connection between the fiber block 11 and other fiber blocks 11 or water-absorbent fibers (fibers 12F) contained in the absorbent core 40. It is useful to form a connection between them. Also, in general, the per unit area of the fiber end The larger the number, the more the entanglement can be improved, and thus the various properties such as the shape retention of the absorptive core 40 can be improved. Furthermore, as described above, the number of fiber ends per unit area on each surface of the fiber block 11 is not uniform. Regarding the number of fiber ends per unit area, the magnitude relationship of “frame surface 112 > base surface 111 ” Therefore, the entanglement of other fibers (other fiber clumps 11 , water-absorbing fibers (fibers 12F)) through the fiber block 11 differs depending on the surface of the fiber block 11 , and the entanglement of the skeleton surface 112 is higher than that of the base surface 111 . That is, the bonding force through the entanglement of the skeleton surface 112 and other fibers is stronger than the bonding force through the basic surface 111. In one fiber block 11, the basic surface 111 and the skeleton surface 112 are connected with other fibers. Binding strength may vary. Generally speaking, the stronger the bonding force, the more restricted the freedom of movement of the fibers to be bonded, and the overall strength (shape retention) of the absorbent core 40 is improved, but on the other hand, the flexibility is lowered. tendency.

In this way, in the absorbent core 40, each of the plurality of fiber blocks 11 contained therein is intertwined with other fibers (the other fiber blocks 11, the absorbent fibers (fibers 12F)) around the absorbent core 40 with two kinds of binding forces, thereby Therefore, the absorptive core 40 has moderate flexibility and strength (shape retention). Furthermore, when the absorbent core 40 having such excellent characteristics is conventionally used as an absorbent body of an absorbent article, a comfortable wearing feeling can be provided to the wearer of the absorbent article, and the wearer of the absorbent article can be effectively prevented from wearing It is a problem that the absorbent core 40 is destroyed by external force such as the wearer's body pressure.

In particular, as described above, the total area of the two basic surfaces 111 of the fiber block 11 ( 11A, 11B) shown in FIG. 5 is larger than the total area of the skeleton surface 112 . Therefore, it means that the total area of the base plane 111, which has relatively low entanglement with other fibers due to the relatively small number of fiber ends per unit area, is larger than the skeleton plane 112, which has the opposite properties. Therefore, the fiber block 11 (11A, 11B) shown in FIG. 5 is compared with the fiber block in which fiber ends are uniformly present on the entire surface, and the other fibers (other fiber blocks 11, water-absorbing fibers (fibers 12F)) in the periphery easy access In addition, even if it is intertwined with other fibers in the periphery, it is easy to intertwined with a relatively weak binding force, so that it is not easy to become a large lump, and excellent flexibility can be imparted to the absorptive core 40 .

On the other hand, the nonwoven sheets and microfiber webs described in Patent Documents 1 and 2 are produced by cutting the raw fiber sheet into an indefinite shape with a cutter such as a chopper as described above, and therefore do not become A sheet-like fiber block having a fixed shape such as the "face" of the basic plane 111 or the skeleton plane 112, and since the external force of the cutting process is applied to the entire fiber block during its manufacture, the entire fiber block is randomly formed. It is difficult for the fiber end portion of the fiber to sufficiently exhibit the above-mentioned effects produced by the fiber end portion.

From the viewpoint of more reliably exerting the above-mentioned effects of the fiber ends, the number N ₁ per unit area of the fiber ends of the basic plane 111 (non-cut plane) and the skeleton plane 112 (cut plane) The ratio of the number N ₂ per unit area of the fiber ends is based on the premise of N ₁ <N ₂ , and is calculated in terms of N ₁ /N ₂ , preferably 0 or more, more preferably 0.05 or more, and preferably 0.90 or less, More preferably, it is 0.60 or less. More specifically, N ₁ /N ₂ is preferably 0 or more and 0.90 or less, and more preferably 0.05 or more and 0.60 or less.

The number N ₁ per unit area of the fiber ends of the basic plane 111 is preferably 0 pieces/mm ² or more, more preferably 3 pieces/mm ² or more, and preferably 8 pieces/mm ² or less, more preferably 6 Pieces/ ^mm2 or less.

The number N ₂ per unit area of the fiber ends of the skeleton surface 112 is preferably 5 pieces/mm ² or more, more preferably 8 pieces/mm ² or more, and preferably 50 pieces/mm ² or less, more preferably 40 Pieces/ ^mm2 or less.

The number per unit area of the fiber ends of the basic plane 111 and the skeleton plane 112 was measured by the following method.

<Measurement method of the number of fiber ends per unit area of each side of the fiber block>

For the member (fiber block) containing the fiber to be measured, use paper double-sided tape (Nicetack NW-15 by Nichiban Co., Ltd.) The measurement sheet was attached to the sample stage. Next, platinum coating was performed on the measurement piece. For the coating, an ion sputtering apparatus E-1030 (trade name) manufactured by Hitachi Naka Precision Co., Ltd. was used, and the sputtering time was set to 120 seconds. For the cut surface of the measurement piece, the fundamental surface and the skeleton surface were observed at a magnification of 100 times using a JCM-6000 electron microscope manufactured by JEOL Co., Ltd. In the observation screen with a magnification of 100 times, a rectangular area with a length of 1.2 mm and a width of 0.6 mm is set at any position on the measurement object surface (basic surface or skeleton surface), and the area of the rectangular area accounts for the area of the observation screen. Adjust the viewing angle, etc. in a manner of 90% or more, and then measure the number of fiber ends contained in the rectangular area. However, in the observation screen with a magnification of 100 times, when the measurement object surface of the fiber block is smaller than 1.2 mm × 0.6 mm, and the ratio of the area of the above-mentioned rectangular area to the entire observation screen does not reach 90%, the use of After the observation magnification was greater than 100 times, the number of fiber ends contained in the rectangular region of the measurement object surface was measured in the same manner as described above. Here, the "fiber end portion" that is the object of the number measurement is the end portion in the longitudinal direction of the constituent fibers of the fiber mass, even if the portion other than the end portion in the longitudinal direction of the constituent fiber (the middle portion in the longitudinal direction) extends from the surface to be measured, The intermediate portion in the longitudinal direction is also not subject to the number measurement. Next, the number per unit area of the fiber end of the measurement object surface (basic surface or skeleton surface) of the fiber block was calculated according to the following formula. For each of 10 fiber lumps, according to the procedure described above, the number of fiber ends per unit area of each of the basic plane and the skeleton plane was measured, and the average value of the plurality of measured values was taken as the fiber end of the measurement target plane. quantity per unit area.

The number of fiber ends per unit area (number/mm ² ) of the measurement object surface (basic surface or skeleton surface) of the fiber block = the number of fiber ends contained in the rectangular area (1.2×0.6mm)/ The area of the rectangular area (0.72mm ² )

On the fundamental plane 111 of the fiber block 11, the fiber block 11A shown in FIG. When viewed in a rectangular shape, from the viewpoint of improving the uniform dispersibility of the fiber blocks 11 in the absorbent core 40, the short sides 111a of the rectangular shape and the fiber blocks 11 ( 11A ) containing the fiber blocks are preferable. The thickness of the absorbent core 40 is the same or shorter. The ratio of the length of the short side 111a to the thickness of the absorptive core 40 is the former/the latter, preferably 0.03 or more, more preferably 0.08 or more, and more preferably 1 or less, more preferably 0.5 or less.

The thickness of the absorptive core 40 is preferably 1 mm or more, more preferably 2 mm or more, more preferably 15 mm or less, more preferably 10 mm or less, and still more preferably 6 mm or less. The thickness of the absorptive core 40 is measured by the above-mentioned method.

It is preferable to set the dimension etc. of each part of the fiber block 11 (11A, 11B) as follows. The size of each part of the fiber block 11 can be measured based on an electron microscope photograph or the like during a specific operation of the outer shape of the fiber block 11 described below.

When the basic plane 111 is in the shape of a rectangle in plan view as shown in FIG. 5(a), the length L1 of the short side 111a is preferably 0.3mm or more, more preferably 0.5mm or more, and preferably 10mm or less, more preferably Preferably, it is 6 mm or less. The length L2 of the long side 111b of the basic surface 111 of the rectangular shape in plan view is preferably 0.3 mm or more, more preferably 2 mm or more, and preferably 30 mm or less, more preferably 15 mm or less.

Furthermore, when the basic plane 111 is the plane with the largest area among the plurality of planes of the fiber block 11 as shown in FIG. The maximum span length is consistent with the diameter of the basic surface 111 of the circular shape in plan view of the disk-shaped fiber block 11B.

The ratio of the length L1 of the short side 111a to the length L2 of the long side 111b is calculated as L1/L2, preferably 0.003 or more, more preferably 0.025 or more, and preferably 0.5 or less.

The thickness T of the fiber block 11, that is, the length T between the two opposing basic surfaces 111 is preferably 0.1 mm Above, more preferably 0.3 mm or more, more preferably 10 mm or less, more preferably 6 mm or less.

Moreover, it is preferable that the absorptive core 40 is mechanically isotropic so that the effect by the presence of the fiber mass 11 is easily exhibited on all surfaces of the absorptive core 40 . Therefore, it is preferable that the fiber mass 11 is uniformly distributed in the whole of the absorptive core 40 at a high density. From this viewpoint, it is preferable that the overlapping portion of the plurality of fiber blocks 11 exists in an arbitrary 10 mm square unit area under projection observation in two directions of the absorptive core 40 which are orthogonal to each other. As the "projection observation in two directions orthogonal to each other" here, typically, projection observation in the thickness direction of the absorptive core (absorber) (that is, the skin-facing surface of the absorptive core or the The case where the non-skin facing surface is viewed), and the projection observation in the direction orthogonal to the thickness direction (that is, the case where the absorbent core is viewed from the side thereof).

FIG. 7( a ) shows an electron micrograph of an example of the fiber mass of the present invention, and FIG. 7( b ) shows a diagram schematically showing the fiber mass 11 based on the electron micrograph. As shown in FIG. 7 , the plurality of fiber blocks 11 contained in the absorbent core 40 may include a body portion 110 , and fibers 11F extending outward from the body portion 110 and having a fiber density lower than that of the body portion 110 . The part 110 (the number of fibers per unit area is less) extends out of the fiber part 113 . In addition, in the absorptive core 40, the fiber block 11 which does not have the extended fiber part 113, ie, the fiber block 11 which consists only of the main body part 110, may be included. The extended fiber portion 113 is one of the fiber end portions existing on each surface (basic surface 111, skeleton surface 112) of the above-mentioned fiber block 11, and is the fiber extending from the outer side of each surface of the fiber block 11 in the fiber end portion. Ends.

The main body portion 110 is a portion formed by dividing the two basic planes 111 facing each other and a skeleton plane 112 connecting the two basic planes 111 . The main body portion 110 is the part that constitutes the main body of the fiber block 11 and forms the fixed outer shape of the fiber block 11. The high flexibility, cushioning, and compression recovery properties of the fiber block 11 basically originate from the main body portion. 110 and therefore larger. the other party On the other hand, the extended fiber portion 113 mainly contributes to improving the intertwining properties of the plurality of fiber blocks 11 contained in the absorptive core 40 or the fiber blocks 11 and the absorbent fibers (fibers 12F), and is directly related to the absorptive core. The improvement of the shape retention property of 40 also affects the uniform dispersibility of the absorbent core 40 of the fiber block 11, etc., and can indirectly reinforce the effect produced by the main body portion 110.

Compared with the extending fiber portion 113 , the main body portion 110 has a higher fiber density, that is, the number of fibers per unit area is larger. In addition, the fiber density of the main body portion 110 itself is generally uniform. The ratio of the body portion 110 to the total mass of the fiber mass 11 is usually at least 40 mass % or more, preferably 50 mass % or more, more preferably 60 mass % or more, and still more preferably 85 mass % or more. The main body portion 110 and the extended fiber portion 113 can be distinguished by the following specific operations of the external shape.

The work of specifying the outer shape of the body portion 110 of the fiber block 11 contained in the absorbent core 40 can be performed by focusing on the difference in fiber density in the absorbent core 40 (how many fibers per unit area). It is performed by checking the "boundary" between the main body portion 110 and other parts, or the difference in the type of fiber and the diameter of the fiber. The fiber density of the main body portion 110 is higher than that of the extending fiber portion 113 existing around it, and generally, synthetic fibers and water-absorbing fibers (fibers 12F) (typically cellulose-based fibers) constituting the main body portion 110 are fibers. ) are different in quality and/or size, so even in the absorbent core 40 in which a plurality of fiber lumps 11 and water-absorbing fibers (fibers 12F) are mixed, the above-mentioned boundary can be easily confirmed by focusing on the above-mentioned aspects. . The boundary confirmed in this way is the periphery (edge) of the basic plane 111 or the skeleton plane 112 , and the basic plane 111 and the skeleton plane 112 are specified by the boundary checking operation, and the main body 110 is specified. This boundary confirmation operation can be implemented by observing the object (absorber 4 ) at a plurality of observation angles as necessary using an electron microscope. In particular, when the fiber blocks 11 contained in the absorbent core 40 are those of the fiber blocks 11A and 11B shown in FIG. Especially when the base surface 111 becomes the surface with the largest area of the fiber block 11, it can be It is relatively easy to specify the basic surface 111 with a large area, so that the specific operation of the outer shape of the main body portion 110 can be smoothly performed.

As shown in FIG. 7 , the extending fiber portion 113 includes the constituent fibers (fibers 11F) of the main body portion 110 extending outward from at least one of the base surface 111 and the skeleton surface 112 forming the outer surface of the main body portion 110 . 7( b ) is a plan view of the fiber block 11 from the side of the basic plane 111 (the plane with the largest area among the plurality of planes of the fiber block 11 ), and a plurality of fibers 11F extend from the skeleton plane 112 intersecting with the basic plane 111 Thus, the extended fiber portion 113 is formed.

The form of the extended fiber portion 113 is not particularly limited. The extended fiber portion 113 may include a single fiber 11F, and may include a plurality of fibers 11F as in the extended fiber bundle portion 113S described below. In addition, the extending fiber portion 113 includes the lengthwise ends of the fibers 11F extending from the main body portion 110, but may include portions other than the lengthwise ends of the fibers 11F in addition to such fiber ends (length the middle part of the direction). That is, in the fiber mass 11, both ends in the longitudinal direction of the constituent fibers (fibers 11F) exist in the main body part 110, and the other part, that is, the intermediate part in the longitudinal direction, extends annularly from the main body part 110 to the outside ( protruding), and the extending fiber portion 113 in this case includes the annular protruding portion of the fiber 11F.

One of the main functions of the extended fiber portion 113 is, as described above, to entangle the plurality of fiber blocks 11 contained in the absorptive core 40, or the fiber blocks 11 and the absorbent fibers (fibers 12F) with each other. Generally speaking, if the extension length of the extended fiber portion 113 from the main body portion 110 becomes longer, or the thickness of the extended fiber portion 113 becomes thicker, or the number of the extended fiber portion 113 in one fiber block 11 increases When the number of objects is increased, the connection between the objects intertwined through the extending fiber portion 113 becomes stronger, and it is difficult to release the intertwining, so that the specific effect of the present invention is more stably exhibited.

When the fiber mass 11 is obtained by cutting the raw fiber sheet 10bs in a fixed shape as shown in FIG. 6 , the extended fiber portion 113 is relatively large in the bone which is the cut surface. On the other hand, the frame surface 112 does not exist at all on the base surface 111 which is a non-cut surface, or even if it exists, the number of the frame surface 112 is smaller than that of the frame surface 112 . The reason why the extended fiber portions 113 are distributed in the frame surface 112 as the cut surface is that most of the extended fiber portions 113 are "fluff" generated by cutting the raw fiber sheet. That is, the skeleton surface 112 formed by cutting the raw fiber sheet 10bs is rubbed as a whole by a cutting mechanism such as a cutter when it is cut, so that the fluff including the constituent fibers (fibers 11F) of the sheet 10bs is easily formed , prone to so-called fluff. Although it also depends on the type of the raw fiber sheet, if the interval between the cutting lines is shortened or the cutting speed is slowed down, the extended fiber portion 113 can be easily formed, and its length can be adjusted. On the other hand, since the basic surface 111 which is a non-cut surface does not have friction with such a cutting mechanism, it is difficult to form fluff, that is, to extend the fiber portion 113 .

Regarding the interval L1a (interval in the first direction, see FIG. 6 ) and interval L2a (interval in the second direction, see FIG. 6 ) between the cutting lines at the time of cutting the raw fiber sheet 10bs, the above-mentioned extending fiber portion 113 is promoted. From the viewpoint of formation, etc., and the viewpoint of making the fiber mass 11 exhibit a specific effect and securing the required size, it is preferably 0.3 mm or more, more preferably 0.5 mm or more, and more preferably 30 mm or less, more preferably 15mm or less.

As shown in FIG. 7 , the fiber block 11 has an extended fiber bundle portion 113S including a plurality of fibers 11F extending outward from the main body portion 110 , more specifically, from the frame surface 112 , as one of the extended fiber portions 113 . At least one of the extended fiber portions 113 of the fiber block 11 may be the extended fiber bundle portion 113S. The extended fiber bundle portion 113S is formed by gathering a plurality of fibers 11F extended from the skeleton surface 112 , and is characterized in that the extended length from the skeleton surface 112 is longer than the extended fiber portion 113 . The extended fiber bundle portion 113S can also exist on the base plane 111 , typically, as shown in FIG. . The reason for this is that the extended fiber portion 113 mainly exists as a The reason for the skeleton surface 112 of the cut surface is the same as described above.

By making the fiber blocks 11 have such a longer and thicker extended fiber bundle portion 113S, which should also be called the large extended fiber portion 113, the fiber blocks 11 or each other or the fiber blocks 11 and the water-absorbing fibers (fibers 12F) are formed. The entanglement is further strengthened, and as a result, the specific effect of the present invention due to the presence of the fiber mass 11 is exhibited more stably. The extended fiber bundle portion 113S can be easily formed by performing the cutting of the raw fiber sheet 10bs (see FIG. 6 ) under the above-described conditions that are prone to fluff.

The extension length of the extended fiber bundle portion 113S from the main body portion 110, that is, the extension length from the skeleton surface 112 (cut surface) is preferably 0.2 mm or more, more preferably 0.5 mm or more, and preferably 7 mm or less, More preferably, it is 4 mm or less. The extended length of the extended fiber bundle portion 113S can be measured in the above-mentioned specific operation (boundary confirmation operation) of the outer shape of the fiber block 11 . Specifically, for example, using a microscope manufactured by Keyence (50 magnification), attach a double-sided tape manufactured by 3M Co., Ltd. to the surface of the transparent acrylic sample stage, and place the fiber block 11 on it and fix it. In the specific operation, after the outer shape of the fiber block 11 is specified, the length of the extension amount in the fibers 11F extending from the outer shape is measured, and the measured extension amount is used as the extension fiber bundle portion 113S. the extension length.

It is preferable that the extended fiber bundle part 113S thermally fuses the plurality of constituent fibers (fibers 11F) to each other. The thermally fused portion of the extended fiber bundle portion 113S generally has a span length in a direction orthogonal to the longitudinal direction of the extended fiber bundle portion 113S compared with other parts (non-thermally fused portion) of the extended fiber bundle portion 113S (Diameter when the cross section of the thermally welded portion is circular) is longer. By providing the extended fiber bundle portion 113S with such a thermal fusion portion, which can also be called a large diameter portion, the strength of the extended fiber bundle portion 113S itself is improved, whereby the fiber blocks 11 intertwined by the extended fiber bundle portion 113S are formed. The entanglement of each other or the fiber mass 11 and the water-absorbing fibers (fibers 12F) is further strengthened. In addition, if the extended fiber bundle portion 113S has a thermal fusion portion, there is an advantage that not only the extended fiber bundles When the bundle portion 113S is in a dry state, and when it absorbs moisture and becomes a wet state, the strength, shape retention, and the like of the extended fiber bundle portion 113S itself are improved. Furthermore, with this advantage, when the absorbent core 40 is applied to an absorbent article, it goes without saying that the absorbent core 40 is in a dry state, even if it absorbs body fluids such as urine or menstrual blood excreted by the wearer. In the case of being in a wet state, the above-mentioned effect due to the presence of the fiber mass 11 can be stably exhibited. Such an extended fiber bundle portion 113S having a thermally fused portion can be obtained by using the "fabricated fiber bundle portion 113S" in the manufacturing step of the fiber block 11 shown in FIG. 6, that is, the cutting step of the raw fiber sheet 10bs of the fiber block 11. The fiber sheet of the thermally fused portion between fibers" was produced as the raw fiber sheet 10bs.

The constituent fibers (fibers 11F) of the fiber mass 11 include synthetic fibers. The synthetic fiber used as the fiber 11F is preferably one whose water absorption is lower than that of the water-absorbing fiber (fiber 12F) (low water absorption), and is particularly preferably a non-water-absorbing synthetic fiber. The constituent fibers (fibers 11F) of the fiber mass 11 may include fiber components other than synthetic fibers (for example, natural fibers), by making the constituent fibers (fibers 11F) of the fiber mass 11 include weakly hydrophilic fibers, preferably non-absorbent fibers , not only when the absorptive core 40 is in a dry state, but also when it absorbs moisture (body fluids such as urine or menstrual blood) and is in a wet state, the above-mentioned effect due to the presence of the fiber mass 11 is stably exerted (Improvement effects of shape retention, softness, cushioning, compression recovery, and resistance to distortion). The content of synthetic fibers constituting fibers (fibers 11F) in the fiber mass 11 is preferably 90 mass % or more, and more preferably 100 mass % with respect to the total mass of the fiber mass 11 , that is, the fiber mass 11 is composed of only synthetic fibers form. In particular, when the synthetic fibers constituting the fibers (fibers 11F) are non-water-absorbent, the above-mentioned effects due to the presence of the fiber lumps 11 are more stably exhibited.

In the present specification, the term "water absorption" means something that can be easily understood by a trader as, for example, pulp can be said to be water absorptive. Similarly, it is also easy to understand that thermoplastic fibers are weakly absorbent Water (especially non-absorbent). On the other hand, the degree of water absorption of the fiber can be compared with the relative difference of the water absorption according to the value of the moisture content measured by the following method, and a better range can also be specified. The larger the value of the moisture content, the stronger the water absorption of the fiber. As a water-absorbent fiber, the moisture content is preferably 6% or more, more preferably 10% or more. On the other hand, the moisture content of the synthetic fiber is preferably less than 6%, more preferably less than 4%. Furthermore, when the moisture content is less than 6%, the fiber can be judged as a non-absorbent fiber.

<Measurement method of moisture content>

The moisture content was calculated by the moisture content test method of JIS P8203. That is, after the fiber sample was left to stand for 24 hours in a test chamber at a temperature of 40°C and a relative humidity of 80% RH, the weight W (g) of the fiber sample before absolute drying was measured in the chamber. After that, it was left to stand in an electric dryer (for example, manufactured by Isuzu Co., Ltd.) at a temperature of 105±2° C. for 1 hour to perform absolute drying treatment of the fiber sample. After the absolute drying treatment, the fiber samples were wrapped with Saran Wrap (registered trademark) manufactured by Asahi Kasei Co., Ltd. in a standard laboratory at a temperature of 20±2°C and a relative humidity of 65±2%. Silica gel (for example, Toyota Chemical Co., Ltd.) is put into a glass dryer (for example, manufactured by Tech jam Co., Ltd.), and it is left to stand until the fiber sample has a temperature of 20±2°C. Then, the constant weight W'(g) of the fiber sample was weighed, and the moisture content of the fiber sample was calculated|required by the following formula. Moisture rate (%)=(W-W'/W')×100

Also, similarly, from the viewpoint of showing excellent effects in terms of shape retention, softness, cushioning properties, compression recovery properties, and resistance to twisting, etc., in either a dry state or a wet state of the absorbent core 40 In other words, the fiber block 11 preferably has a three-dimensional structure in which a plurality of thermoplastic fibers are thermally fused to each other.

Furthermore, in order to obtain such a fiber mass in which a plurality of thermally fused portions are dispersed three-dimensionally 11. The synthetic fibers used as the constituent fibers (fibers 11F) of the fiber mass 11 are preferably thermoplastic fibers. In addition, as described above, the extended fiber bundle portion 113S preferably has a thermal fusion portion, and by making the constituent fibers (fibers 11F) of the fiber block 11 thermoplastic fibers, the extended fiber bundle portion 113S can also be obtained with a relatively high ratio. good form.

In order to obtain a fiber mass 11 in which a plurality of thermally fused portions are three-dimensionally dispersed, the raw fiber sheet 10bs (see FIG. 6 ) may be configured in the same manner. Moreover, such a raw fiber in which a plurality of thermally fused portions are three-dimensionally dispersed The sheet 10bs can be produced by subjecting a fiber web or a nonwoven fabric mainly composed of thermoplastic fibers to heat treatment such as hot air treatment as described above.

Examples of non-water-absorbent synthetic resins (thermoplastic resins) that are preferable as the material of the constituent fibers (fibers 11F) of the fiber mass 11 include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and the like. ; Polyamides such as nylon 6 and nylon 66; polyacrylic acid, polyalkyl methacrylate, polyvinyl chloride, polyvinylidene chloride, etc.; can be used alone or in combination of two or more. In addition, the fiber 11F may be a single fiber composed of one kind of synthetic resin (thermoplastic resin) or a blended polymer in which two or more kinds of synthetic resins are mixed, or may be a composite fiber. The term "conjugated fiber" here refers to a synthetic fiber (thermoplastic fiber) obtained by compounding two or more kinds of synthetic resins with different components using a spinning head and spinning simultaneously, and refers to a plurality of components in the longitudinal direction of the fiber. The above continuous structures are connected to each other within the single fiber. The form of the conjugate fiber includes a core-sheath type, a side-by-side type, and the like, and is not particularly limited.

Moreover, it is preferable that the contact angle of the fiber mass 11 and water is less than 90 degrees, especially 70 degrees or less, from a viewpoint of further improving the introduction property of the bodily fluid in the initial excretion. Such fibers are obtained by conventionally treating the above-mentioned non-water-absorbing synthetic fibers with a hydrophilizing agent. As the hydrophilizing agent, a usual surfactant can be used.

<Measuring method of contact angle>

The fiber was taken out from the measurement object (absorbent core), and the contact angle of water with respect to the fiber was measured. As a measuring apparatus, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. was used. Deionized water was used for the measurement of the contact angle. The amount of liquid ejected from an ink jet water droplet ejection unit (CTC-25, a pulse ejector with a diameter of 25 μm in the ejection unit, manufactured by Cluster Technology) was set to 20 picoliters, and the water droplets were dropped directly above the fibers. The dripping condition was recorded on a high-speed recording device connected to a horizontally arranged camera. From the viewpoint of subsequent image analysis, the video recording device is preferably a personal computer incorporating a high-speed capture device. In this measurement, images were recorded every 17 msec. In the recorded images, use the attached software FAMAS (the software version is set to 2.6.2, the analysis method is set to droplet method, the analysis method is set to θ/2 method, the image processing algorithm is set to no reflection, and the image The processing image mode is set to the frame, the critical level is set to 200, and no curvature correction is performed.) Perform image analysis on the initial image of the water droplet falling on the fiber, and calculate the angle formed by the surface of the water droplet in contact with the air and the fiber, as Contact angle. The fiber taken out from the object to be measured was cut to a fiber length of 1 mm, and the fiber was placed on the sample stage of the contact angle meter and maintained horizontally. For each fiber, the contact angles at two different locations were measured. Measure the contact angle of N=5 pieces to 1 decimal place, average the measured values of 10 places in total, and define the obtained value (rounded up to the second decimal place) as the contact angle between the fiber and water . The measurement environment was set at a room temperature of 22±2°C and a humidity of 65±2%RH.

Furthermore, when the absorber (absorptive core) to be measured is used as a constituent member of other articles such as absorbent articles, and the absorber is taken out for evaluation and measurement, the absorber is subjected to adhesive, fusion, etc. When it is fixed to other structural members, within the range that does not affect the contact angle of the fibers, the adhesive force is removed by blowing cold air with cold spray to the fixed part and then taken out. This procedure is common to all assays in this specification.

As the water-absorbent fiber (fiber 12F), the water-absorbent fiber previously used as a forming material of an absorber of such an absorbent article can be used. Examples of water-absorbing fibers include natural fibers such as wood pulp such as conifer pulp and hardwood pulp, and non-wood pulp such as cotton pulp and hemp pulp; modified pulp such as cationized pulp and mercerized pulp; recycled materials such as cupro, rayon, etc. Fibers, etc.; one of these can be used alone or two or more of them can be used in combination. As described above, in view of the fact that the main function of the absorbent fibers (fibers 12F) is to improve the liquid absorbency of the absorber 4, as the absorbent fibers (fibers 12F), natural fibers, regenerated fibers (cellulose fibers) are preferred. ).

In the absorber 4, the content mass ratio of the fiber mass 11 and the water-absorbing fiber (fiber 12F) is not particularly limited, as long as the content of the fiber mass 11 (synthetic fiber; fiber 11F) and the water-absorbing fiber (fiber 12F) are determined. The type and the like can be appropriately adjusted. For example, when the constituent fibers (fibers 11F) of the fiber mass 11 are thermoplastic fibers (non-water-absorbent synthetic fibers) and the water-absorbent fibers (fibers 12F) are cellulose-based water-absorbent fibers, the present invention can be more reliably exerted. From the viewpoint of a specific effect, the content ratio of the fiber mass 11 and the water-absorbent fiber (fiber 12F) is preferably 20/80 to 80 in terms of the former (fiber mass 11)/the latter (water-absorbent fiber (fiber 12F)). /20, more preferably 40/60~60/40.

The content of the fiber lumps 11 in the absorber 4 is preferably 20% by mass or more, more preferably 40% by mass or more, preferably 80% by mass or less, more preferably 80% by mass or less, relative to the total mass of the absorber 4 in the dry state. 60 mass % or less.

The content of the water-absorbent fibers (fibers 12F) in the absorber 4 is preferably 20% by mass or more, more preferably 40% by mass or more, and preferably 80% by mass or less with respect to the total mass of the absorber 4 in a dry state , more preferably 60 mass % or less.

The basis weight of the fiber mass 11 in the absorber 4 is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and preferably 640 g/m ² or less, more preferably 480 g/m ² or less.

The basis weight of the absorbent fibers (fibers 12F) in the absorber 4 is preferably 32 g/m ² or more, more preferably 80 g/m ² or more, and preferably 640 g/m ² or less, more preferably 480 g/m ² the following.

The absorber 4 can be manufactured in the same manner as an absorber containing such a fibrous material. As described above, the fiber block 11 is shown in FIG. 6 , and the raw fiber sheets (sheets whose composition is the same as that of the fiber block 11 and whose size is larger than that of the fiber block 11 ) can be separated into each other by using a cutting mechanism such as a cutter. It is produced by cutting in two intersecting (orthogonal) directions, and the plurality of fiber blocks 11 thus produced are "fixed-shaped fiber aggregates" of uniform shape and size (for example, the main body 110 has a rectangular parallelepiped shape). The absorber 4 containing the fiber mass 11 and the water-absorbing fibers (fibers 12F) can be conventionally produced using, for example, a known fiber stacking device provided with a rotating drum. Typically, the fiber accumulation device includes a drum having a concave portion for accumulation formed on the outer peripheral surface thereof, and a drum inside which has a raw material (fiber mass 11, water-absorbing fiber (fiber 12F)) for conveying the absorbent core 40 to the concave portion for accumulation. The duct of the flow path, while rotating the drum around the rotation axis in the circumferential direction of the drum, makes the air flow (vacuum air) generated in the flow path by suction from the inner side of the drum. The conveyed raw material is accumulated in the concave portion for accumulation. The fiber accumulation formed in the concave portion for accumulation by this fiber accumulation step is the absorptive core 40 .

The basis weight of the absorber 4 may be appropriately adjusted depending on the application and the like. For example, when the use of the absorber 4 is an absorber of absorbent articles such as disposable diapers or menstrual sanitary napkins, the basis weight of the absorber 4 is preferably 100 g/m ² or more, more preferably 200 g/m ² or more, And it is preferably 800 g/m ² or less, more preferably 600 g/m ² or less. Furthermore, as described above, the basis weight of the absorbent body 4 shown here can be directly applied to the absorbent core 40 .

As mentioned above, although this invention was demonstrated based on the embodiment, this invention is not limited to the said embodiment, It can change suitably.

For example, in the above-described embodiment, the absorber 4 includes the absorptive core 40 and the core wrap covering the absorptive core 40 Sheet 41, but may not include core sheet 41.

In addition, not all the fiber blocks (synthetic fiber aggregates) contained in the absorptive core of the present invention may be fiber aggregates having a fixed shape such as the fiber blocks 11, as long as they are within the scope of not departing from the gist of the present invention. In addition to the fixed fiber aggregates, a very small amount of amorphous fiber aggregates may be further contained.

The absorbent article of the present invention widely includes articles for absorbing body fluids (urine, soft stool, menstrual blood, sweat, etc.) discharged from the human body, and in addition to the above-mentioned menstrual sanitary napkins, also includes menstrual shorts, so-called unfolding type disposables with fixing belts Diapers, shorts-type disposable diapers, incontinence pads, etc. With regard to the above-described embodiments of the present invention, the following additional notes are further disclosed.

<1> An absorber, which is used in direct or indirect contact with the skin, and has a skin-facing surface disposed at a position relatively close to the user's skin during use, and a non-contact surface disposed at a position relatively far from the user's skin The skin-opposite surface contains a fiber mass containing synthetic fibers and a water-absorbent fiber, and a plurality of the fiber mass or the fiber mass and the water-absorbent fiber are intertwined with each other, and the content of the fiber mass relative to the water-absorbent fiber. The ratio is smaller than the above-mentioned non-skin-opposing surface side.

<2> The absorber according to the above <1>, wherein the mass ratio of the fiber mass relative to the water absorbent fiber gradually increases from the skin-opposing surface side toward the non-skin-opposing surface side.

<3> An absorber which is used in direct or indirect contact with the skin, and has a skin-facing surface disposed relatively close to the user's skin during use, and a non-contact surface disposed relatively far from the user's skin The face opposite to the skin contains fiber blocks comprising synthetic fibers and water-absorbing fibers, and a plurality of the fiber blocks or the fiber blocks and the water-absorbing fibers are intertwined with each other, and the content of the fiber blocks is relative to the above-mentioned fiber blocks and The combination of the above absorbent fibers The ratio in terms of mass content is that the above-mentioned skin-opposing surface side is smaller than the above-mentioned non-skin-opposing surface side (that is, the above-mentioned non-skin-opposing surface side is larger than the above-mentioned skin-opposing surface side).

<4> The absorber according to the above <3>, wherein the ratio of the mass content of the fiber mass to the total mass content of the fiber mass and the water-absorbing fiber goes from the skin-opposing surface side toward the non-skin The opposite side gradually increases.

<5> The absorber according to any one of the above <1> to <4>, wherein the ratio of the mass of the fiber mass to the total mass of the fiber mass and the water-absorbing fiber is opposite to the skin The surface side is 0 mass % or more and 60 mass % or less, and the non-skin opposing surface side is 50 mass % or more and 100 mass % or less, and the difference between the two is 15 mass % or more.

<6> The absorber as described in said <5> whose said difference is 80 mass % or more.

<7> The absorber according to any one of the above <1> to <6>, wherein the fiber block has a main body portion divided by two opposing base planes and a skeleton plane intersecting the two base planes.

<8> The absorber according to the above <7>, wherein the total area of the two basic planes is larger than the total area of the skeleton planes.

<9> The absorber according to the above <7> or <8>, wherein the base surface has a rectangular shape in plan view, and the short side of the rectangular shape is equal to or shorter than the thickness of the absorber.

<10> The absorber according to the above <9>, wherein the length of the short side of the basic surface is 0.3 mm or more, preferably 0.5 mm or more, and 10 mm or less, preferably 6 mm or less.

<11> The absorber according to the above <9> or <10>, wherein the length of the long side of the basic surface is 0.3 mm or more, preferably 2 mm or more, and 30 mm or less, preferably 15 mm or less.

<12> The absorber according to any one of the above <7> to <11>, wherein the number per unit area of the fiber ends present in each of the basic surface and the skeleton surface is greater than that of the skeleton surface the fundamentals.

<13> The absorber according to any one of the above <7> to <12>, wherein the number N ₁ per unit area of the fiber ends present on the basic plane and the fiber ends present on the skeleton plane The ratio N ₁ /N ₂ of the number N ₂ per unit area is 0 or more and 0.90 or less, preferably 0.05 or more and 0.60 or less.

<14> The absorber according to any one of the above <7> to <13>, wherein the number per unit area of the fiber ends present in the basic plane is 0 or more and 8 or less, preferably 3 or more and 6 or less.

<15> The absorber according to any one of the above <7> to <14>, wherein the number per unit area of the fiber ends present on the skeleton surface is 5 or more and 50 or less, preferably 8 or more and 40 or less.

<16> The absorber according to any one of the above <7> to <15>, wherein the fiber block has an extended fiber portion including fibers extending outward from the body portion and the fibers The density is lower than the body portion.

<17> The absorber according to the above <16>, wherein at least one of the extending fiber portions is an extending fiber bundle portion including a plurality of fibers extending outward from the frame surface.

<18> The absorber according to any one of the above <1> to <17>, wherein the skin-facing surface side contains a water-absorbent polymer.

<19> The absorber according to any one of the above <1> to <18>, wherein the mass ratio of the fiber mass to the water-absorbent fiber is 20/80 to 80/20 in terms of the former/the latter.

<20> The absorber according to any one of the above <1> to <19>, wherein the fiber The synthetic fibers contained in the dimensional block are non-absorbent.

<21> The absorber according to any one of the above <1> to <20>, wherein the water-absorbent fiber is a cellulose-based water-absorbent fiber.

<22> The absorber according to any one of the above <1> to <21>, wherein the contact angle between the fiber mass and water is less than 90 degrees, preferably 70 degrees or less.

<23> The absorber according to the above <22>, wherein the fiber mass is treated with a hydrophilizing agent.

<24> The absorber according to any one of the above <1> to <23>, wherein the absorber includes an absorptive core and a core wrapping material.

<25> The absorber according to any one of the above <1> to <24>, wherein in the absorber, the fiber block is not only bonded to other fiber blocks or the water-absorbing fibers by intertwining in the absorber, but also to It can exist in a state of being intertwined with other fiber blocks or the above-mentioned absorbent fibers.

<26> The absorber according to the above <25>, wherein the total number of the fiber blocks bonded by the intertwining and the fiber blocks in the state capable of being intertwined is greater than the total number of the fiber blocks in the absorber. It is preferable to account for more than half, more preferably more than 70%, and still more preferably more than 80%.

<27> The absorber according to any one of the above <1> to <26>, wherein the total number of the fiber blocks having the bonding portion with the other fiber blocks or the water-absorbent fibers is preferably 70% or more , More preferably, 80% or more of the junction is formed by the intertwining of fibers.

<28> The absorber according to any one of the above <1> to <27>, wherein the fiber mass is derived from a nonwoven fabric.

<29> An absorbent article comprising the absorber according to any one of the above <1> to <28>.

Example

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

[Example 1]

A menstrual sanitary napkin having the same basic structure as the sanitary napkin 1 shown in FIG. 1 was produced.

A hot air non-woven fabric with a basis weight of 30 g/m ² was used as the front sheet, and a polyethylene resin film (FL-KDJ100nN, manufactured by Daika Industry Co., Ltd.) with a basis weight of 37 g/m ² was used as the back sheet. The absorbent system used fiber mass and absorbent fibers as the fiber material of the absorbent core, and then used a separately prepared core wrapping material containing toilet paper with a basis weight of 16 g/m ² , and was conventionally manufactured using a known fiber stacking device. Manufacture of the fiber block was manufactured by cutting the raw fiber sheet into small squares according to FIG. 6 . The arrangement of the fiber materials (fiber blocks, water-absorbing fibers) in the absorber of Example 1 is the same as that of the absorber 4 shown in FIG. An arrangement that gradually increases toward the non-skin-opposing surface side toward the face side.

As the raw fiber sheet of the fiber mass, a non-water-absorbent thermoplastic fiber containing polyethylene and polyethylene terephthalate resin treated with the following composition A (contact angle with water 68 degrees) was used as A hot-air nonwoven fabric with a basis weight of 21 g/m ² constituting fibers (fiber sheet having thermally fused portions constituting fibers). As the water-absorbent fiber, conifer bleached kraft pulp (NBKP) was used. The fiber block (shaped synthetic fiber aggregate) used in the absorber has a main body portion in the shape of a cuboid as shown in FIG. The thickness T is 0.6 mm. Further, the number per unit area of the fiber ends of the base surface 111 was 3.2 pieces/mm ² , and the number per unit area of the fiber ends of the skeleton surface 112 was 19.2 pieces/mm ² .

(Composition of Composition A)

‧Potassium Alkyl Phosphate (Potassium Hydroxide Neutralized by Kao Co., Ltd. Gripper 4131): 25% by mass

‧Sodium salt of dialkyl sulfosuccinate (Pelex OT-P manufactured by Kao Co., Ltd.): 10% by mass

‧Alkyl (stearyl) betaine (Amphitol 86B manufactured by Kao Co., Ltd.): 15% by mass

‧Polyoxyethylene (addition molar number: 2) stearylamide (Amisol SDE manufactured by Kawaken Fine Chemicals): 30% by mass

‧Polyoxyethylene, polyoxypropylene modified polysiloxane (X-22-4515 manufactured by Shin-Etsu Chemical Co., Ltd.): 20% by mass

[Example 2]

The arrangement of the fiber material (fiber block, water-absorbing fiber) in the absorber is the same as that of the absorber 4A shown in FIG. 4 , and the fiber block occupancy rate in the thickness direction and the fiber block ratio are set at two positions different from each other. In addition to the configuration of the above, menstrual sanitary napkins were produced in the same manner as in Example 1, as Example 2. That is, the skin-facing side of the absorbent system in the menstrual sanitary napkin of Example 2 is the part 12P rich in absorbent fibers, the non-skin-opposing side is the part 11P rich in fiber lumps, and the two parts 12P, 11P The interfaces between them are bonded to each other by the entanglement of the constituent fibers, and the interface is located in the center of the thickness direction of the absorber.

[Example 3]

In Example 2, the fiber mass occupancy rate of the site 12P rich in water-absorbent fibers was set to 0 mass %, that is, the content of water-absorbent fibers on the skin-facing side of the absorber was set to 100 mass %, and The fiber block occupancy rate of the site 11P of the fiber block was set to 100 mass %, that is, the water-absorbent fiber occupancy rate of the non-skin-facing surface side of the absorber was set to 0 mass %, and the same was used except that Absorber, the menstrual sanitary napkin of Example 3 was produced.

[Example 4]

In Example 3, the fiber block was changed to one whose short side 111a of the basic plane 111 was 0.8 mm, the long side 111b was 5.0 mm, and the thickness was 0.6 mm. In this modified fiber block, the number of fiber ends per unit area was set to be the same as in Example 2. Except for the above points, a menstrual sanitary napkin including the same absorber as in Example 3 was produced, and it was set as Example 4.

[Comparative Example 1]

The absorber of a commercially available menstrual sanitary napkin (manufactured by Unicharm Co., Ltd., trade name "Tanom Pew Slim 23cm") was used as Comparative Example 1 as it was. In the absorption system of Comparative Example 1, a synthetic fiber and a cellulosic fiber (water-absorbing fiber) were mixed, and the fiber lump was not included.

[Comparative Example 2]

A menstrual sanitary napkin was produced in the same manner as in Example 1, except that the absorber was changed to the following with reference to Patent Document 1, and it was referred to as Comparative Example 2.

The absorbent system used in Comparative Example 2 used an amorphous non-woven fabric sheet as a fiber block in the absorbent core, and the absorbent core was covered with a core wrap material and then hot-air processing was performed to make the absorbent core contained in the absorbent core. The non-woven fabric sheets were the same as the absorber used in Example 1 except that they were thermally fused to each other. In the hot air step performed on the above-mentioned absorber, the mixed aggregate (length 210mm×width 66mm) of the non-woven fabric sheet and pulp fiber was left for 600 seconds in an electric dryer (for example, manufactured by Isuzu Manufacturing Co., Ltd.) at a temperature of 150°C. , so that the non-woven fabric sheets are thermally fused to each other. The used unshaped non-woven fabric sheet was produced by tearing the same hot air non-woven fabric used in Examples 1 and 2 in any direction, and its span length in a plan view was about 25 mm.

[Performance evaluation]

For the menstrual sanitary napkins of the respective Examples and Comparative Examples, the compression work (w-WC), twist rate, and surface diffusion area in a wet state were measured by the following methods, respectively. In addition, regarding Example 4, the recovery work (d-WC') in the dry state and the compressive strain rate (d-ΔT/T ₀ ) in the dry state were also measured by the following methods, respectively. The results are shown in Table 1 below.

<Measurement method of compression work (WC)>

Generally speaking, the compression work (WC) of a known sample can be expressed by the measured value obtained by KES (Kawabata Evaluation System) manufactured by Kato Tech Co., Ltd. (Reference: Standardization and Analysis of Texture Evaluation (2nd Edition)) , Author Kawabata Yoshio, published July 10, 1980). Specifically, the compression work (WC) and the compression recovery ratio (RC) were measured using an automatic compression test apparatus KES-G5 manufactured by Kato Tech Co., Ltd. The measurement procedure is as follows.

The "absorbent article with an absorbent body (menstrual sanitary napkin)" as a sample was mounted on the test bench of the compression test apparatus. Next, the sample was compressed between steel plates having a circular plane with an area of 2 cm ² . The compression speed was set to 0.02 cm/sec, and the maximum compression load was set to 490 mN/cm ² . The reply process is also measured at the same speed. The compression work (WC) is represented by the following formula, and the unit is “mN·cm/cm ² ”. In the formula, T _m , T ₀ and Pa represent the thickness under _a load of 490 mN/cm ² , the thickness under a load of 4.9 mN/cm ² , and the load (mN/cm ² ) during measurement (compression process).

The compression work thus calculated is the compression work (w-WC) in the wet state of the sample. As the value of w-WC is larger, it is judged that the cushioning property is higher and the evaluation is higher.

"The absorbent article provided with the absorber in a wet state" which is the measurement object of the said measurement method was adjusted by the following method. First, the absorbent article before being injected with defibrillated horse blood was placed for 24 hours in an environment with an air temperature of 23°C and a relative humidity of 50% RH, and adjusted for drying. state of absorbent articles. The absorbent article in the dry state was placed horizontally so that the surface sheet side (skin-opposing surface side) became the upper side, and an oval injection port (long diameter 50 mm, short diameter 23 mm) was placed on the front sheet, 3.0 g of defibrillated horse blood was injected through the injection port, and after standing for 1 minute, 3.0 g of defibrillated horse blood was injected, and the state was maintained for 1 minute after injection to obtain an absorbent article having an absorber in a wet state. In addition, the defibrillated horse blood injected into the measurement object was the same as that prepared in the following <Method for Measuring Surface Diffusion Area>.

<Measurement method of response work (WC')>

The recovery work (WC') of the sample can be measured using the above-mentioned KES. Specifically, the recovery work (WC') was measured using an automatic compression test apparatus KES-G5 manufactured by Kato Tech Co., Ltd. The measurement procedure is as follows.

The "absorbent article with an absorbent body (menstrual sanitary napkin)" as a sample was mounted on the test bench of the compression test apparatus. Next, the sample was compressed between steel plates having a circular plane with an area of 2 cm ² . The compression speed was set to 0.2 cm/sec, and the maximum compression load was set to 2450 mN/cm ² . The reply process is also measured at the same speed. The response work (WC') is expressed by the following formula, and the unit is "mN·cm/cm ² ". In the formula, T _m , T ₀ and P _b respectively represent the thickness under a load of 2450 mN/cm ² , the thickness under a load of 4.9 mN/cm ² , and the load (mN/cm ² ) during measurement (recovery process).

Furthermore, the response power (WC') will not be displayed on the measurement result screen of KES-G5, but displayed on the measurement result screen is the compression response rate ( RC). In this case, use the parameters (WC, RC) displayed in the measuring device, The reply work (WC') was calculated from the following formula.

[Equation 3] WC' = RC × WC ÷100

The above "recovery work in dry state (d-WC')" was carried out by using "absorbent article in dry state (menstrual sanitary napkin)" as the sample in the above <Measurement method of recovery work (WC')>. Determination. The absorbent system contained in the absorbent article in the dry state is not used and does not absorb liquid, and is in a dry state. According to the present inventors, the larger the value of d-WC' is, the higher the compression recovery property in the dry state of the absorber is judged to be, and the evaluation becomes higher.

<Measurement method of compressive strain rate (ΔT/T ₀ )>

The compressive strain rate (ΔT/T ₀ ) of the sample can be measured using the above-mentioned KES. Specifically, the compressive strain rate (ΔT/T ₀ ) was measured using an automated compression test apparatus KES-G5 manufactured by Kato Tech Co., Ltd. The measurement procedure is as follows.

The "absorbent article with an absorbent body (menstrual sanitary napkin)" as a sample was mounted on the test bench of the compression test apparatus. Next, the sample is compressed between steel plates having a circular plane with an area of 2 cm ² , and the load at the time of compression is gradually increased, and the measurement object is measured at the time point at which the load reaches a specific maximum value (maximum load). The thickness (compressed thickness) T _m . Make sure that the measurement object is not wrinkled or bent. The measurement conditions of the compression tester are as follows.

‧Compression speed: 0.2mm/sec

‧Maximum load: 2450mN/cm ²

‧SENS: 10

‧DEF: 20

In addition, the initial thickness (T ₀ ) of the object to be measured was defined as the thickness at the time point when the above-mentioned load was 103.9 mN/cm ² . The compressive strain rate (%) was calculated from the following formula.

Compressive strain rate (ΔT/T ₀ )={(T ₀ -T _m )/T ₀ )}×100

The above "compressive strain rate in dry state (d-ΔT/T ₀ )" is obtained by using "Dry absorbent articles (menstrual sanitary napkins ₎ ")" was measured as a sample. The absorbent system contained in the absorbent article in the dry state is not used and does not absorb liquid, and is in a dry state. According to the present inventors, as the value of d-ΔT/T ₀ is larger, it is judged that the softness of the absorber in a dry state is higher, and the evaluation becomes higher.

The measurement conditions of the above-mentioned d-WC' and d-ΔT/T ₀ were respectively set to 10 times the speed of the general conditions of KES-G5. According to the inventors and others, the measurement conditions can further reflect the actions of the wearer such as walking and sitting.

<Measurement method of twist ratio>

The twist rate of menstrual napkins was evaluated using a powered female lower body mannequin. First, the center width of the sanitary napkin (the horizontal length of the vertical center of the sanitary napkin) (the center width before walking) was measured, and the sanitary napkin was attached to shorts and worn on a female mannequin. Next, the mannequin was made to walk at a speed of 100 steps/min for 30 minutes. During the walking of the mannequin, 1.5 g of defibrillated horse blood was injected into the sanitary napkin in the wearing state for 15 seconds after walking for 3 minutes, and the operation was repeated. This was performed 6 times, and a total of 9 g of defibrillated horse blood was injected into the sanitary napkin. Next, the sanitary napkin was removed from the shorts, the center width (center width after walking) was measured, and the twist rate (%) was calculated from the center width before walking and the center width after walking according to the following formula. The smaller the numerical value of the twist rate, the less easily the sanitary napkin is twisted, and the higher the evaluation becomes. In addition, the defibrillated horse blood injected into the measurement object was the same as that prepared in the following <Method for Measuring Surface Diffusion Area>.

Twist rate=[{(central width before walking)-(central width after walking)}÷(central width before walking) Center width)]×100

<Measurement method of surface diffusion area>

On an inclined surface having an angle of 45° with respect to the horizontal plane, the measurement object (menstrual sanitary napkin) was fixed with its skin-opposing surface facing the inclined surface, and the following operations were performed, that is, the skin-opposing surface of the measurement object was subjected to the following operations for 23 seconds. 1.5 g of defibrillated horse blood was injected, and after standing for 3 minutes, the same amount of defibrated horse blood was injected into the same injection site for the same time. This operation of injecting and leaving the defibrated horse blood was repeated 6 times, and a total of 9 g of the defibrated horse blood was injected into the measurement object. After the injection operation was completed, the diffusion area of the defibrillated horse blood on the skin-opposite surface of the measurement object was measured and set as the surface diffusion area of the measurement object.

Referring to FIG. 8 to supplement the above-mentioned <Method for Measuring Surface Diffusion Area>, the measurement object S (menstrual sanitary napkin) was set to have a quadrilateral shape in plan view of 240 mm×75 mm. The measurement table 100 used for measurement has an inclined surface 100a whose angle θ with the horizontal surface is 45°. The measurement object S is placed on the inclined surface 100a so that its skin-opposing surface faces the inclined surface 100a, and the acrylic plate 101 having an area larger than the thickness of the measurement object S by 3 mm is placed on the measurement object S. The defibrillated horse blood line injected as simulated blood into the measurement object S was measured using a B-type viscometer (model TVB-10M manufactured by Toki Sangyo Co., Ltd., measurement conditions: rotor No. 19, 30 rpm, 25° C., 60 seconds). The resulting viscosity becomes 8mPa·s. As such defibrillated horse blood, for example, defibrillated horse blood manufactured by Nippon Bio-test Laboratories Co., Ltd. can be used, and the viscosity can be adjusted to the above-mentioned specific range by adjusting the ratio of blood cells and plasma as necessary. The injection position of the defibrillated horse blood in the measurement object S was set at the center of the skin-opposing surface of the measurement object S (the part indicated by the arrow in FIG. 8 ), and a microtube pump (Tokyo RIKEN Co., Ltd., which is not shown in the figure) was used. Ltd.) injection. A pipe (not shown) is connected to the pump, and the end of the pipe is connected to the opposite side of the connection side of the pump. The measurement object S is attached to the inclined surface 100a, and the defibrillated horse blood is injected into the measurement object S through the tube. The diffusion area of the defibrillated horse blood on the skin-opposing surface of the measurement object S can be measured by drawing the distribution area of the defibrillated horse blood of the measurement object S on the OHP sheet, and using the image analysis software NexusNewQube( Nexus Corporation) conventionally processed the OHP sheet.

As shown in Table 1, in each example, a plurality of fiber blocks or fiber blocks and water-absorbing fibers are intertwined, and the relationship between the size of the fiber block occupancy rate "non-skin-opposing surface side>skin-opposing surface side" is established. , therefore, compared with Comparative Examples 1 and 2 that do not satisfy these requirements, the value of the compression work w-WC in the wet state is larger, so the cushioning property is excellent, and the twist rate is smaller, so it is not easy to twist, and because of the size Therefore, the liquid introduction property is excellent. In particular, from the comparison of each Example and Comparative Example 2, it can be seen that in order to obtain a product that has a large compression work and excellent cushioning properties even in a wet state. In the absorber, it is effective to set the fiber blocks in a fixed shape and to bind the fiber blocks to each other by intertwining.

[Industrial Availability]

The absorber of the present invention has high cushioning properties and is not easy to be twisted, and has excellent liquid introduction properties, and can improve wearing feeling when applied to absorbent articles.

Moreover, since the absorbent article of this invention is provided with this high-quality absorber, it is excellent in wearing feeling and leak-proofness.

1: Menstrual pads

2: front sheet

3: back sheet

4: Absorber

5: Absorbent body

6: Side Sheets

11: Fiber Blocks

11F: Fiber

12F: Fiber

13: Water Absorbent Polymer

40: Absorbent core

41: Chip material

Y: horizontal

Claims (28)

An absorbent body, which is used in direct or indirect contact with the skin, and has a skin-facing surface arranged at a position relatively close to the user's skin during use, and a non-skin-facing surface arranged at a position relatively far away from the user's skin noodle, Containing fiber blocks comprising synthetic fibers and water-absorbent fibers, and a plurality of the fiber blocks or the fiber blocks and the water-absorbent fibers are intertwined with each other, and The content-mass ratio of the said fiber lump with respect to the said water-absorbent fiber is smaller than the said non-skin-opposing surface side of the said skin-opposing surface side. The absorber according to claim 1, wherein the mass ratio of the fiber mass relative to the water-absorbent fiber gradually increases from the skin-opposing surface side toward the non-skin-opposing surface side. An absorbent body, which is used in direct or indirect contact with the skin, and has a skin-facing surface arranged at a position relatively close to the user's skin during use, and a non-skin-facing surface arranged at a position relatively far away from the user's skin noodle, Containing fiber blocks comprising synthetic fibers and water-absorbent fibers, and a plurality of the fiber blocks or the fiber blocks and the water-absorbent fibers are intertwined with each other, and The ratio of the content mass of the fiber mass to the total content mass of the fiber mass and the water-absorbing fiber is larger on the non-skin-opposing surface side than on the skin-opposing surface side. The absorbent body according to claim 3, wherein the ratio of the mass content of the fiber mass to the total mass content of the fiber mass and the water-absorbing fiber gradually increases from the skin-opposing surface side toward the non-skin-opposing surface side . The absorbent body according to claim 1 or 3, wherein the ratio of the mass of the fiber mass to the total mass of the fiber mass and the water-absorbent fiber is 0 mass % or more and 60 mass % or less on the skin-opposing surface side , and it is 50 mass % or more and 100 mass % or less on the said non-skin opposing surface side, and the difference between both is 15 mass % or more. The absorber according to claim 5, wherein the difference is 80% by mass or more. The absorbent body according to claim 1 or 3, wherein the above-mentioned fiber block has a main body portion formed by dividing two basic planes facing each other and a skeleton plane intersecting with the two basic planes. The absorbent body of claim 7, wherein the total area of the above-mentioned two basic planes is greater than the total area of the above-mentioned skeleton planes. The absorbent body according to claim 7, wherein the base surface has a rectangular shape in plan view, and the short side of the rectangular shape is equal to or shorter than the thickness of the absorbent body. The absorbent body of claim 7, wherein the number per unit area of the fiber ends present in each of the above-mentioned basic surface and the above-mentioned skeleton surface is that the skeleton surface is larger than the basic surface. The absorbent body according to claim 7, wherein the ratio N ₁ /N of the number N ₁ per unit area of the fiber ends existing in the above-mentioned basic surface and the number N ₂ per unit area of the fiber ends existing in the above-mentioned skeleton surface ₂ is 0 or more and 0.90 or less. The absorber of claim 11, wherein the ratio N ₁ /N ₂ is 0.05 or more and 0.60 or less. The absorbent body according to claim 7, wherein the number of fiber ends present in the above-mentioned basic surface per unit area is 0 or more and 8 or less. The absorbent body according to claim 7, wherein the number of fiber ends present in the above-mentioned skeleton surface per unit area is 5 or more and 50 or less. The absorbent body according to claim 7, wherein the fiber block has an extended fiber portion, and the extended fiber portion includes fibers extending outward from the main body portion and has a lower fiber density than the main body portion. The absorbent body according to claim 15, wherein at least one of the extending fiber portions is an extending fiber bundle portion including a plurality of fibers extending outward from the frame surface. The absorber according to claim 1 or 3, wherein the skin-opposing surface side contains a water-absorbent polymer. The absorbent body according to claim 1 or 3, wherein the mass ratio of the fiber mass to the water-absorbent fiber is 20/80 to 80/20 in terms of the former/the latter. The absorbent body according to claim 1 or 3, wherein the synthetic fibers contained in the above-mentioned fibrous mass are non-absorbent. The absorbent body according to claim 1 or 3, wherein the water-absorbent fibers are cellulose-based water-absorbent fibers. The absorbent body of claim 1 or 3, wherein the contact angle of the above-mentioned fibrous mass with water is less than 90 degrees. The absorbent body of claim 21, wherein the above-mentioned fibrous mass is treated with a hydrophilizing agent. The absorbent body according to claim 1 or 3, wherein the absorbent body comprises an absorbent core and a core wrap. The absorbent body according to claim 1 or 3, wherein the fibrous mass in the absorbent body can be intertwined with other fibrous mass or the aforementioned absorbent fiber in addition to being combined with other fibrous mass or the aforementioned absorbent fiber by intertwining in the aforementioned absorbent body state exists. The absorbent body according to claim 24, wherein the total number of fiber blocks bonded by intertwining and the fiber blocks in a state capable of being intertwined accounts for more than half of the total number of fiber blocks in the absorbent body. The absorbent body according to claim 1 or 3, wherein 70% or more of the total number of the fiber blocks having a bond with the other fiber blocks or the water-absorbent fibers are those that form the bond by intertwining fibers. The absorbent body according to claim 1 or 3, wherein the above-mentioned fibrous mass is from non-woven fabric. An absorbent article provided with the absorber according to claim 1 or 3.

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