Absorber, method for producing absorber, and absorbent article

Abstract

To provide an absorber having multiple absorption functions at a low cost.SOLUTION: An absorber comprises: a first liquid-permeable sheet which forms one surface of the absorber and has liquid permeability; a first SAP layer containing SAP particles, which are composed of superabsorbent polymers; a sheet-shaped base layer having liquid permeability; a second SAP layer containing SAP particles which are identical in a composition to the SAP particles included in the first SAP layer, are also identical in a production method, and have a value calculated by dividing the surface area by volume that differs from that of the SAP particles included in the first SAP layer; and a second liquid-permeable sheet which forms the other surface of the absorber and has liquid permeability, wherein these are laminated in the thickness direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an absorber, a method for manufacturing the absorber, and an absorbent article.

Background Art

[0002] Absorbent articles such as diapers are known (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An absorbent article has an absorber and absorbs liquid generated from the human body. The absorber is required to have an absorption performance for quickly absorbing the inflowing liquid. In addition to this, there are also additional performances for improving convenience. Such additional performances include, for example, not allowing the internal liquid to flow back to the skin surface even when a strong pressure is applied after liquid absorption, and continuously absorbing the liquid that flows in repeatedly over a long period of time. Which of these performances is emphasized depends on the situation in which the wearer is placed. Therefore, it is desirable to provide an absorbent article having an optimal absorber for each required additional performance. However, if a plurality of types of absorbers are prepared for each required performance, there is a problem that the provision cost becomes high.

[0005] An object of the present invention is to provide an absorber having a plurality of absorption performances at low cost.

Means for Solving the Problems

[0006] The absorber according to one aspect of the present invention includes a first liquid-permeable sheet that forms one surface of the absorber and has liquid permeability, a first SAP layer containing SAP particles that are superabsorbent polymers, a sheet-like base layer having liquid permeability, and a second SAP layer containing SAP particles that are made of the same components and by the same manufacturing method as the SAP particles contained in the first SAP layer and have a value obtained by dividing the surface area by the volume different from that of the SAP particles contained in the first SAP layer, and a second liquid-permeable sheet that forms the other surface of the absorber and has liquid permeability, which are laminated in the thickness direction.

Advantages of the Invention

[0007] According to the present invention, an absorber having a plurality of absorption performances can be provided at low cost.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

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Figure 4

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Figure 8

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Figure 13

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, with reference to the drawings, the absorber according to the embodiment of the present invention will be described. Note that the configurations of the following embodiments are examples, and the present invention is not limited to the configurations of these embodiments.

[0010] <First Embodiment> In the present embodiment, for a tape-type disposable diaper (hereinafter simply referred to as "diaper"), which is an example of an absorbent article to which the absorber is assembled, the longitudinal direction is defined as the direction connecting the front body portion disposed to face the abdomen of the wearer and the back body portion disposed to face the back. Between these front body portions (one side in the longitudinal direction) and the back body portions (the other side in the longitudinal direction) (at the center in the longitudinal direction), there is a crotch portion disposed under the crotch of the wearer (opposite to the crotch). Further, in the state where the diaper is worn by the wearer (hereinafter abbreviated as "worn state"), the side facing the wearer's skin (the inner side in the worn state) is defined as the skin side, and the opposite side of the skin side (the outer side in the worn state) is defined as the non-skin side. Furthermore, the direction connecting the skin side and the non-skin side is defined as the thickness direction, and the direction orthogonal to both the longitudinal direction and the thickness direction is defined as the width direction. In addition, viewing from the thickness direction is defined as a plan view. Also, the front, rear, left, and right of the diaper 1 mean the directions that coincide with the front, rear, left, and right of the wearer in the state where the diaper 1 is worn by the wearer. For example, when referring to the left-right direction in the present application, it means the direction that coincides with the left and right of the wearer in the state where the diaper 1 is worn by the wearer, and when referring to the front-rear direction in the present application, it means the direction that coincides with the front and rear of the wearer in the state where the diaper 1 is worn by the wearer.

[0011] FIG. 1 is a perspective view of a diaper according to the present embodiment. The diaper 1 has a length along the longitudinal direction and a length along the width direction perpendicular to the longitudinal direction. The diaper 1 has a crotch region 1B, which is a region corresponding to the crotch of the wearer covering the pubic area of ​​the wearer when worn, a front body region 1F, which is located in front of the crotch region 1B and corresponds to the front body of the wearer, and a back body region 1R, which is located behind the crotch region 1B and corresponds to the back body of the wearer. Tapes 2L and 2R that can be attached to a front patch 2F provided on the non-wearer side surface of the front body region 1F are provided on both left and right edges of the back body region 1R. When the tapes 2L and 2R are attached to the front patch 2F with the front body region 1F arranged on the wearer's abdomen and the back body region 1R arranged on the wearer's back, the diaper 1 is fixed to the wearer's body in a state of surrounding the wearer's waist circumference and thighs. Since the diaper 1 is fixed to the wearer's body in this manner, the wearer can stand and walk around while wearing the diaper 1.

[0012] In the diaper 1, an absorbent capable of absorbing and retaining liquid is mainly arranged in the crotch region 1B. In addition, in order to prevent the formation of gaps between the diaper 1 and the wearer's skin that serve as a liquid outflow path, the diaper 1 is provided with leg gathers 3AL, 3AR in the area surrounding the wearer's legs (thighs), leak-proof walls 3BL, 3BR are provided on the inner side of the leg gathers 3AL, 3AR in the width direction of the diaper 1, and a waist gather 3R is provided in the area surrounding the wearer's abdominal circumference. The leg gathers 3AL, 3AR, the leak-proof walls 3BL, 3BR, and the waist gather 3R are brought into close contact with the wearer's skin by the contraction force (elastic force) of the elastic member. Therefore, liquid discharged from the wearer's private parts is absorbed into the absorbent of the diaper 1 without leaking out of the diaper 1. The elastic member may be selected from thread-like rubber (thread rubber) or strip-like rubber, etc., as appropriate.

[0013] FIG. 2 is an exploded perspective view of the diaper 1. FIG. 3 is a cross-sectional view of the diaper 1 in a non-worn state, cut along the center in the longitudinal direction along the width direction. FIG. 4 is a plan view of the diaper 1 in an extended state, seen from the skin side. In FIG. 4, the illustration of the expansion and contraction members 4C, 4SL, and 4SR is omitted. The diaper 1 has a cover sheet 4 that forms the outer surface in the worn state. The cover sheet 4 is a sheet-like member having a substantially rectangular appearance with gathers 4KL and 4KR provided at a portion corresponding to the long side, and forms the exterior surface of the diaper 1. The gathers 4KL and 4KR are provided at the portions where the wearer's thighs are located (the leg-around regions 10L and 10R shown in FIG. 4). The cover sheet 4 is provided for reinforcing the back sheet 5 and improving the touch described later. For example, in order to suppress leakage of excrement, a non-woven fabric made of a liquid-impermeable thermoplastic resin can be used as the material. Examples of the liquid-impermeable thermoplastic resin include polyethylene (PE) and polypropylene (PP). The cover sheet 4 is not limited to a single-layer structure, and may have a multi-layer (two-layer) structure having an inner cover sheet and an outer cover sheet. Note that the cover sheet 4 forms the outer peripheral shape (outer shape) of the absorbent pad 1. The cover sheet 4 forms an exterior surface in which the front body region 1F, the crotch region 1B, and the back body region 1R are continuously provided.

[0014] The diaper 1 has a backsheet 5 (an example of the "non-skin side sheet" in the present disclosure), an absorber 6, and a topsheet 7 (an example of the "skin side sheet" in the present disclosure), which are laminated in this order on the skin side of the cover sheet 4. The backsheet 5, the absorber 6, and the topsheet 7 are all sheet-like members having a substantially rectangular appearance, and are laminated on the cover sheet 4 in a state where the longitudinal direction coincides with the longitudinal direction of the cover sheet 4. The backsheet 5 is a sheet formed of a water-impermeable thermoplastic resin as a material, like the cover sheet 4, to suppress leakage of excrement. The backsheet 5 is preferably composed of a material having moisture permeability to suppress stuffiness in the worn state. The topsheet 7 is a sheet-like member disposed on the skin side of the wearer. The topsheet 7 has liquid permeability in part or all of it. Therefore, in the worn state of the diaper 1, the liquid excreted from the wearer enters the absorber 6 through the topsheet 7 that can come into contact with the wearer's skin and is absorbed there. For example, woven fabric, non-woven fabric, and porous film can be used as the material of the topsheet 7. The topsheet 7 may have hydrophilicity. The basis weight of the topsheet 7 is, for example, 16~35 g / m 2 ². The topsheet 7 may have intermittent squeezing grooves. By providing the squeezing grooves, the granular feeling of the contents of the absorber 6 can be reduced.

[0015] The backsheet 5, the absorber 6, and the topsheet 7 all extend from the front crotch region 1F to the rear crotch region 1R. Therefore, when the crotch of the wearer is covered with the cover sheet 4 on which the backsheet 5, the absorber 6, and the topsheet 7 are laminated, both longitudinal ends of the backsheet 5, the absorber 6, and the topsheet 7 are positioned on the ventral side and the dorsal side of the wearer. That is, the crotch of the wearer is covered with the absorber 6 from the ventral side to the dorsal side of the wearer. Therefore, no matter whether the wearer discharges the liquid out of the body in a posture with the belly down or a posture with the back down, the discharged liquid comes into contact with the absorber 6 through the topsheet 7. The topsheet 7 and the backsheet 5 are longer in the longitudinal direction than the absorber 6 and extend to the respective ends of the front crotch region 1F and the rear crotch region 1R of the diaper 1.

[0016] Further, the diaper 1 is provided with expansion and contraction members 4SL and 4SR for forming the above-described leg gathers 3AL and 3AR so as to expand and contract in the longitudinal direction of the diaper 1 between the cover sheet 4 and the back sheet 5. The expansion and contraction members 4SL and 4SR are provided in an appropriate number (three in this embodiment) determined according to the elastic force (contracting force) required in the design of the diaper 1 and the like. As shown in FIG. 4, the leg gathers 3AL and 3AR are arranged to include the leg circumferential regions which are the portions where the wearer's thighs are located at both ends in the width direction of the crotch region 1B. The leg circumferential regions 10L and 10R are arranged at both ends in the width direction of the crotch region 1B. Further, the leg gathers 3AL and 3AR are formed in the arrangement regions of the expansion and contraction members 4SL and 4SR.

[0017] The diaper 1 also has long and narrow strip-shaped side sheets 8L and 8R (a pair of leakage-preventing sheets). The side sheets 8L and 8R are sheets having non-water permeability (liquid impermeability) provided at the long side portions of the top sheet 7. Similar to the cover sheet 4, the side sheets 8L and 8R are provided with constrictions 8KL and 8KR at the portions where the wearer's thighs are located (the leg circumferential regions 10L and 10R shown in FIG. 4). And expansion and contraction members 8EL and 8ER for forming leakage-preventing walls 3BL and 3BR are arranged along the longitudinal direction of the diaper 1 on the side sheets 8L and 8R. When the diaper 1 is in the worn state, that is, when the diaper 1 is in a U-shaped form in side view, the side sheets 8L and 8R are drawn in the longitudinal direction by the contracting force of the expansion and contraction members 8EL and 8ER and rise from the top sheet 7 to become leakage-preventing walls 3BL and 3BR that prevent the outflow of liquid.

[0018] Note that an expansion and contraction member 4C for preventing a gap from being formed between the diaper 1 and the wearer's abdominal circumference is provided along the longitudinal direction of the diaper 1 inside the width direction of the diaper 1 rather than the expansion and contraction members 4SL and 4SR. The expansion and contraction member 4C is provided according to the elastic force (contracting force) required in the design of the diaper 1 and the like.

[0019] Further, the elastic member 9ER for forming the waist gather 3R described above is disposed in a waist sheet 9R provided between the back sheet 5 and the top sheet 7 at a position further dorsal than the end of the absorber 6. The waist sheet 9R is disposed at a position on the front end side (the rear end side of the diaper 1) rather than the end on the back waist region 1R side of the absorber 6, away from the absorber 6, and between the top sheet 7 and the back sheet 5, and is a sheet-like member extending wider in the width direction than the absorber 6. The waist sheet 9R is formed by laminating two nonwoven sheets, and the elastic member 9ER is adhered in an extended state in the width direction of the diaper 1 between the two nonwoven sheets. The elastic member 9ER is disposed in the waist sheet 9R with the longitudinal direction, which is the stretching direction, in the left-right direction of the diaper 1. For this reason, the waist sheet 9R has shrinkability in the width direction of the diaper 1 and functions as a belt-like elastic member together with the elastic member 9ER. When the tapes 2L and 2R provided on both the left and right sides of the waist sheet 9R are adhered to the front patch 2F on the ventral side of the wearer, the elastic member 9ER exerts a contracting force to bring the diaper 1 into close contact with the wearer, preventing a gap from being formed between the diaper 1 and the wearer's abdominal circumference.

[0020] Also, a waist sheet 9F is provided between the back sheet 5 and the top sheet 7 at a position further ventral than the end of the absorber 6. The waist sheet 9F is disposed at a position on the front end side (the front end side of the diaper 1) rather than the end on the front waist region 1F side of the absorber 6, away from the absorber 6, and between the top sheet 7 and the back sheet 5, and is a sheet-like member extending wider in the width direction than the absorber 6. The waist sheet 9F is formed by laminating two nonwoven sheets in the same manner as the waist sheet 9R. Note that no elastic member is disposed in the waist sheet 9F, and thus the waist sheet 9F has no shrinkability. Note that the basis weight of the waist sheets 9F and 9R is 7 to 20 g / m 2 and, as an example, is 15 g / m 2 is.

[0021] In the present application, the state where the sheets overlap is not limited to the form in which the overlapping sheets are in contact with each other entirely, but is a concept including the form in which a part of the sheets overlaps. Further, the state where the sheets are adhered to each other is a concept including the form in which another sheet is interposed between the sheets and the sheets are adhered to each other through the other sheet.

[0022] <Absorbent body> Next, the detailed structure of the absorbent body 6 will be described. FIG. 5 is a diagram showing the structure of the absorbent body. As described above, the absorbent body 6 has an absorbent core 6C and a core wrap sheet 6W. The core wrap sheet 6W is a liquid-permeable sheet. The core wrap sheet 6W covers the absorbent core 6 C to prevent collapse and suppress the leakage of the SAP particles described later.

[0023] In the example of this figure, the core wrap sheet 6W is composed of two sheets, an upper core wrap sheet 6WA that covers one surface of the absorbent body 6 and a lower core wrap sheet 6WB that covers the other surface of the absorbent body 6. The upper core wrap sheet 6WA and the lower core wrap sheet 6WB are preferably made of the same material. For example, a fine-fiber air-through nonwoven fabric excellent in water permeability can be used. Note that different materials may be used for the upper core wrap sheet 6WA and the lower core wrap sheet 6WB. The upper core wrap sheet 6WA is an example of the first liquid-permeable sheet in the present disclosure. The lower core wrap sheet 6WB is an example of the second liquid-permeable sheet in the present disclosure.

[0024] In this embodiment, the absorption core 6C has a SAP layer composed of SAP particles. The SAP layer contains an absorbent resin such as SAP (Super Absorbent Polymer), which is a hydrophilic polymer having a cross-linked structure capable of absorbing and retaining water. The SAP particles of this embodiment refer to those obtained by granulating a resin composition containing SAP. The "resin composition containing SAP" as mentioned here is a concept encompassing both a composition consisting only of SAP and a composition having SAP as the main component and containing other substances to such an extent that it does not adversely affect water absorption. Examples of the "other substances" include additives (such as surface modifiers added for the purpose of hydrophobizing the particle surface) and unreacted monomers remaining during the synthesis of SAP, etc.

[0025] Among the SAP particles, there are those not fixed inside the absorption core 6C. Also, the absorption core 6C does not contain short fibers that would prevent the movement of SAP particles. The core wrap sheet 6W has the role of suppressing the collapse of the absorption core 6C and suppressing the dissipation of SAP particles.

[0026] The absorption core 6C includes a sheet-like base layer 6I having liquid permeability. The base layer 6I is a fiber sheet such as a non-woven fabric for example. On one side of the base layer 6I, a first SAP layer 6A is disposed, and on the other side sandwiching the base layer 6I, a second SAP layer 6B is disposed. The SAP particles constituting the first SAP layer 6A and the second SAP layer are formed of the same material by the same manufacturing method and are of the same composition, but their particle sizes are different. For example, the SAP particles constituting the first SAP layer 6A are larger in particle size than the SAP particles constituting the second SAP layer 6B. Since the second SAP layer has SAP particles with a small particle size, the surface area per volume of the SAP particles is larger for the SAP particles constituting the second SAP layer than for the SAP particles constituting the first SAP layer. In other words, in the example of this figure, it can be said that the value obtained by dividing the average surface area of the SAP particles contained in the first SAP layer 6A by the average volume is smaller than the value obtained by dividing the average surface area of the SAP particles contained in the second SAP layer 6B by the average volume.

[0027] To calculate the surface area per unit, the upper core wrap sheet 6WA and the lower core wrap sheet 6WB are removed from the absorber 6, and the SAP particles are detached from each of the first SAP layer which is the upper SAP and the second SAP layer which is the lower SAP using an adhesive tape. Next, the SAP particles are measured with a microscope to obtain the particle diameter. Since it is difficult to measure the surface area of the SAP particles, the SAP particles are approximated as spheres to calculate the surface area of the SAP particles and the volume of the SAP particles. From the calculated volume of the SAP particles, the number of particles per unit volume can be calculated, and from the surface area and volume of the SAP, the surface area per unit volume of the SAP can be calculated. These operations are performed multiple times to calculate the average value.

[0028] FIG. 6 is a table showing the measurement of the particle diameter of the SAP particles collected in the first SAP layer, approximating the SAP particles as spheres, and calculating the number of particles per unit volume and the surface area per unit volume. FIG. 7 is a table showing the measurement of the particle diameter of the SAP particles collected in the second SAP layer, approximating the SAP particles as spheres, and calculating the number of particles per unit volume and the surface area per unit volume. In FIGS. 6 and 7, the particle diameter, surface area, and volume are calculated for 30 SAP particles each constituting the first SAP layer and the second SAP layer, and the average value of each value is obtained.

[0029] Although it takes a certain amount of time for the moisture reaching the SAP layer to be absorbed by the SAP particles, the absorption time depends on the surface area of the SAP particles. Since the surface area per volume of the SAP particles constituting the second SAP layer 6B is larger than the surface area per volume of the SAP particles constituting the first SAP layer 6A, the moisture that has penetrated into the second SAP layer is absorbed faster than the first SAP layer. For example, when the first SAP layer is arranged on the skin side and the second SAP layer is arranged on the non-skin side, the exudate generated from the human body and infiltrated from the skin side reaches the second SAP layer 6B without being much absorbed by the first SAP layer 6A, and is preferentially absorbed by the SAP particles arranged in the second SAP layer 6B with a larger surface area in terms of volume ratio. Since the second SAP layer is far from the skin surface, even if pressure is applied due to a change in body position or the like at the timing after absorption, it is possible to suppress the reverse flow of the exudate to the skin side. Therefore, the comfort of the wearer is maintained.

[0030] It is also possible to arrange the second SAP layer 6B on the skin side and the first SAP layer 6A on the non-skin side. When the SAP particles come into contact with moisture, they expand and gelate. When the gelled SAP particles are arranged in the liquid flow path, a so-called gel blocking phenomenon occurs in which the gelled SAP particles block the liquid flow path. If the gel blocking phenomenon occurs in the SAP layer arranged on the skin side, the inflow of the exudate to the SAP layer arranged on the non-skin side is inhibited. In this state, even if there is absorption capacity in the SAP layer arranged on the non-skin side, the exudate cannot reach the non-skin side. In this state, the exudate is likely to ooze out to the skin side, so the wearing feeling is likely to deteriorate.

[0031] Here, the particle size of the SAP particles constituting the second SAP layer 6B is smaller than the particle size of the SAP particles constituting the first SAP layer 6A. Therefore, the degree of swelling of the SAP particles constituting the second SAP layer 6B is smaller than the degree of swelling of the SAP particles constituting the first SAP layer 6A. When the second SAP layer 6B is disposed on the skin side, even if the SAP particles constituting the second SAP layer 6B absorb water and swell, gaps remain between the particles. For this reason, the discharged liquid can flow into other layers having absorption capacity without causing a so-called gel blocking phenomenon. Thus, by disposing the second SAP layer 6B on the skin side, it is possible to provide the absorber 6 that is less likely to have a reduced absorption capacity even when worn for a long time and repeatedly receiving the inflow of discharged liquid.

[0032] The base layer 6I may be composed of natural fibers such as pulp fibers, but it is more preferably composed of synthetic fibers made of a thermoplastic resin. For example, when pulp fibers are used as the base layer 6I, since the base layer 6I itself absorbs and retains moisture, the discharged liquid does not flow smoothly to the SAP layer disposed on the non-skin side of the base layer 6I. Since synthetic fibers do not retain moisture as compared with natural fibers, the discharged liquid that has flowed into the absorber 6, passed through the SAP layer disposed on the skin side of the base layer 6I, and reached the base layer 6I flows smoothly to the SAP layer disposed on the non-skin side of the base layer 6I and is absorbed there, so that the absorption rate can be increased as a whole. The base layer 6I may be composed of, for example, a bulky air-through nonwoven fabric.

[0033] Among the SAP particles, there are non-crushed products (pearl products) having a substantially spherical shape and crushed products having complex corners. Although either of them can be used for the absorber according to the present embodiment, it is more preferable to use crushed products. When a sheet formed of fibers is used as the base layer 6I and crushed products are used as the SAP particles, the SAP particles bite into the base layer 6I. In the absorber according to the present embodiment, each SAP layer does not contain short fibers or the amount of short fibers contained is less than that in the past, and the SAP cannot be sufficiently fixed by the short fibers. Instead, it is composed of fibers By providing the base layer 6I and using crushed products as SAP particles, the position of the SAP can be fixed. Such an absorber 6 contains no short fibers or has a small amount of short fibers, so it is thin, and since the SAP particles are fixed, it is less likely to lose its shape. On the other hand, when using non-crushed products, even if they spill out of the absorber 6, there is an advantage that they are less likely to cause irritation to the wearer's skin surface or other structures.

[0034] Here, the inter-fiber spacing Ra, which is the inter-fiber void size of the base layer 6I, when the sheet thickness (μm) is Ta, the fineness (dtex) of the fibers constituting the sheet is da, the basis weight (g / m 2 ) of the sheet is Wa, and the average single fiber diameter (μm) of the fibers constituting the sheet is Da, Ra = (100 × Ta × da) / (Wa × Da) - Da ··· Equation (1) is a numerical value obtained thereby, and more specifically, it is 380 μm. The inter-fiber void size of the base layer is preferably in the range of 330 μm to 390 μm with a margin from this numerical value.

[0035] In this embodiment, the average particle diameter of the SAP particles arranged in the first SAP layer 6A was 427 μm as shown in FIG. 6. For the first SAP layer 6A, if the average particle diameter of the SAP particles is 381 μm to 450 μm or less, the SAP particles can appropriately penetrate into the base layer 6I. In this embodiment, the average particle diameter of the SAP particles arranged in the second SAP layer 6B was 308 μm as shown in FIG. 7. For the second SAP layer, if the average particle diameter of the SAP particles is 280 μm to 380 μm, the SAP particles can appropriately penetrate into the base layer 6I. Note that the average particle diameter of the SAP particles arranged in the first SAP layer 6A may be 350 μm or more and 1000 μm or less. Also, the average particle diameter of the SAP particles arranged in the second SAP layer 6B can be 50 μm or more and 350 μm or less.

[0036] Also, the particle size of the SAP particles disposed in the second SAP layer 6B is smaller than the fiber-to-fiber spacing Ra of the base layer 6I. Therefore, the SAP particles disposed in the second SAP layer 6B can pass through the base layer 6I. Due to this property, for example, SAP particles with a small particle size that constitute the second SAP layer 6B are first mixed in the first SAP layer 6A and then placed on the base layer 6I, and by applying pressure thereto, only the SAP particles with a small particle size can be passed through to form the second SAP layer 6B. Also, at this time, when a crushed type is used as the SAP particles, the SAP particles are entangled with the fibers of the base layer 6I. By being entangled with the fibers of the base layer 6I, the SAP particles are fixed and the collapse of the mold is suppressed.

[0037] Thus, in the diaper 1 according to the present embodiment, in the manufacturing process, the absorber 6 can be placed in an inverted manner. And when the first SAP layer 6A is placed so as to come to the skin side, an effect can be obtained that the absorbed discharged liquid does not easily flow back, and when the second SAP layer 6B is placed so as to come to the skin side, even if the discharged liquid is repeatedly introduced, the absorption performance hardly decreases and an effect that wearing can be performed for a long time can be obtained. In this way, according to the performance required for the diaper, by placing the absorber 6 having different effects on the front and back in an inverted manner, it is not necessary to incorporate a plurality of types of absorbers into the diaper 1 according to the absorption performance. Therefore, it is possible to supply the diaper 1 that meets a plurality of demands while reducing the manufacturing cost.

[0038] FIG. 8 is a cross-sectional view when the center in the width direction of the diaper 1 in the non-wearing state is cut along the longitudinal direction. As shown in FIG. 8, the core wrap sheet 6W is non-adhesive on the skin side and the non-skin side at the end side in the longitudinal direction of the diaper 1. The reason for this non-adhesion will be described later. Also, the waist sheets 9F, 9R are adhered to the topsheet 7 on the skin side and adhered to the backsheet 5 on the non-skin side. For this adhesion, for example, a hot melt adhesive is used.

[0039] When the absorbent core is formed of pulp, the SAP particles are entangled with the fibers of the pulp and absorb It is difficult to fall off from the absorption core. However, in the present embodiment, the absorption core 6C does not contain pulp. In the absorber 6 having such a configuration, the SAP particles do not get entangled with fibers or the like, and the SAP particles are likely to fall off at the end portions in the width direction and the longitudinal direction of the absorber 6.

[0040] In addition, the diaper 1 according to the present embodiment may contain unfixed SAP particles. If no countermeasures are taken for the diaper, these SAP particles may leak to the outside of the diaper. For example, if a gap is formed between the topsheet and the backsheet, the SAP particles that have fallen off from the absorber may spread to the end portion side in the longitudinal direction of the diaper and may leak out from between the topsheet and the backsheet.

[0041] Therefore, the diaper 1 according to the present embodiment includes waist sheets 9F and 9R disposed on the end side in the longitudinal direction of the absorber 6. Further, the top sheet 7 and the back sheet 5 are weakly adhered or non-adhered to each other on the end side of the absorber 6, that is, between the absorber 6 and the waist sheets 9F and 9R. More specifically, in the regions within D1 and D2 shown in FIG. 8, the top sheet 7 and the back sheet 5 are weakly adhered or non-adhered. Note that D1 is the distance between the absorber 6 and the waist sheet 9R on the back waist region 1R side. D2 is the distance between the absorber 6 and the waist sheet 9F on the front waist region 1F side. The specific lengths of D1 and D2 are omitted. Here, the weak adhesion means an adhesive force that allows the sheets adhered to each other to be peeled off without breaking them, and it is an adhesive force assumed to be peeled off naturally by, for example, the contraction force of the elastic member when the diaper 1 is worn. By making the top sheet 7 and the back sheet 5 non-adhered or weakly adhered in the regions within D1 and D2, the SAP particles fall off from the first SAP layer 6A and the second SAP layer 6B, enter between the top sheet 7 and the back sheet 5, and peel them off from each other, thereby forming a space (hereinafter, may be referred to as the "SAP accommodation space") between the top sheet 7 and the back sheet 5, and the SAP particles can be accommodated in the SAP accommodation space. Further, since the waist sheets 9F and 9R are disposed on the end side in the longitudinal direction rather than the SAP accommodation space, the movement of the SAP particles to the end side rather than the waist sheets 9F and 9R is suppressed. Since the waist sheets 9F and 9R are relatively strongly adhered to the top sheet 7 and the back sheet 5, it is possible to prevent the SAP accommodation space from communicating with the outside of the diaper 1 and suppress the leakage of the SAP particles to the outside. Further, since the waist sheets 9F and 9R are wider than the absorber 6, even if the SAP particles leaked into the SAP accommodation space move in the width direction, the waist sheets 9F and 9R can suppress the leakage of the SAP particles.

[0042] Also, in the region within D2, when the topsheet 7 and the backsheet 5 are non - adhered, no hot - melt adhesive is applied between the topsheet 7 and the backsheet 5. When the topsheet 7 and the backsheet 5 are weakly adhered, a small amount of hot - melt adhesive is applied between them. Therefore, the region within D2 has relatively low rigidity and is easy to bend. Here, when the hook portions of the tapes 2L and 2R in the worn state of the diaper 1 are adhered to the loop portion of the front patch 2F and the front (ventral) ends of the tapes 2L and 2R overlap the region within D2 in the thickness direction, the diaper 1 is more likely to bend on the non - skin - side in front of the front end. In this way, the diaper 1 can block the SAP particles at the bent portion when the topsheet 7 and the backsheet 5 bend on the non - skin - side in the region within D2 in the worn state.

[0043] Also, the waist sheets 9F and 9R have a thickness larger than the average particle diameter of the SAP particles. For example, the average particle diameter of the SAP particles is 350 μm and is sized to be in the range of 150 - 650 μm. The waist sheets 9F and 9R are thicker than the particle diameter of the SAP particles, for example, 0.8 mm or more. Even if the SAP particles move into the SAP accommodation space, since the SAP accommodation space is located between the absorber 6 and the waist sheets 9F and 9R, due to the thickness of the absorber 6 and the waist sheets 9F and 9R, the SAP particles in the SAP accommodation space can be prevented from touching the wearer's skin surface through the topsheet 7 Thereby, the diaper 1 can prevent giving the wearer the thickness and foreign - body sensation of the SAP particles that have moved into the SAP accommodation space.

[0044] In addition, when the distances D1 and D2 between the absorber 6 and the waist sheets 9F and 9R are set to 10 mm or less, since the skin surfaces of the wearer's abdomen and back are curved, it is difficult for the skin to touch the top sheet 7 in the SAP accommodation space. In order not to give the wearer a foreign body sensation of SAP even when body pressure is applied to the diaper 1, the absorber 6 and the waist sheets 9F and 9R preferably have a thickness of 1 mm or more. By setting the absorber 6 and the waist sheets 9F and 9R to a thickness of 1 mm or more, the wearer's skin is brought into contact with the absorber 6 and the waist sheets 9F and 9R, and the wearer's skin is prevented from touching the SAP in the SAP accommodation space. Therefore, the diaper 1 can suppress giving the wearer a discomfort caused by the contact of the SAP particles.

[0045] Also, the distances D1 and D2 in the longitudinal direction of the diaper 1 between the absorber 6 and the waist sheets 9F and 9R are preferably at least twice the average particle diameter of the SAP particles. More preferably, the distances D1 and D2 are at least ten times the average particle diameter of the SAP particles. When the SAP particles fall off from the first SAP layer 6A and the second SAP layer 6B and a SAP accommodation space is formed between the top sheet 7 and the back sheet 5, by setting the distances between the absorber 6 and the waist sheets 9F and 9R as described above, the force that the SAP particles peel off the top sheet 7 and the back sheet 5 can be prevented from acting on the adhesion between the waist sheets 9F and 9R and the top sheet 7 and the back sheet 5. Therefore, the diaper 1 can prevent the waist sheets 9F and 9R from peeling off from the top sheet 7 and the back sheet 5, and can suppress the leakage of the SAP particles.

[0046] Also, the waist sheet 9F on the front body region 1F side has no shrinkability. For this reason, on the front body region 1F side, since no shrinkage force in the width direction is applied to the core wrap sheet 6W, the core wrap sheet 6W is suppressed from opening in the thickness direction. In addition, when a shrinkage force is applied to the absorber 6, the SAP particles are likely to fall off from the first SAP layer 6A and the second SAP layer 6B. However, on the front body region 1F side, no shrinkage force is applied to the absorber 6, and the SAP particles are less likely to fall off.

[0047] Note that the crotch region side of the waist sheet 9F and the back sheet 5 may be weakly adhered or non - adhered. As a result, a storage space for SAP is also formed between the crotch region side of the waist sheet 9F and the back sheet 5. When SAP particles are stored in the storage space, the waist sheet 9F is arranged closer to the skin side than the storage space, so that the skin contact (foreign body sensation) of the SAP particles in the storage space can be reduced. Also, as described above, when the top sheet 7 and the back sheet 5 are bent to the non - skin side in the region within D2 in the worn state, the skin contact of the SAP particles in the storage space can be further reduced.

[0048] Also, as shown in FIG. 4, the leakage - preventing walls 3BL and 3BR formed by the side sheets 8L and 8R and the elastic members 8EL and 8ER are arranged along the width - direction ends of the top sheet 7 and extend in the longitudinal direction of the diaper 1. The side sheets 8L and 8R are joined to the width - direction end sides of the top sheet 7. A hot - melt adhesive is used for this joining. The side sheets 8L and 8R are adhered to the top sheet 7 and the cover sheet 4 outside the width direction from the folding lines 30L and 30R extending in the longitudinal direction, and are not adhered to the top sheet 7 inside the folding lines 30L and 30R. Therefore, in the worn state of the diaper 1, due to the contraction force of the elastic members 8EL and 8ER provided on the side sheets 8L and 8R in the state of being extended in the longitudinal direction of the diaper 1, the inside of the side sheets 8L and 8R from the folding lines 30L and 30R stands up to the skin side, and thereby, the leakage - preventing walls 3BL and 3BR are formed.

[0049] When the leakage-preventing walls 3BL and 3BR stand up, the fixing parts 31L and 31R serving as the longitudinal starting points of this standing are formed. Note that in FIG. 4, the fixing parts 31L and 31R are shown filled in. The fixing parts 31L and 31R are inside the width direction of the diaper 1 rather than the folding lines 30L and 30R, and are formed on the longitudinal end sides of the absorber 6. The fixing parts 31L and 31R are formed on both sides of the front body region 1F and the rear body region 1R, and each fixing part 31L and 31R is arranged across the absorber 6 and the waist sheets 9F and 9R in the thickness direction. The fixing parts 31L and 31R are formed by applying a hot melt adhesive between the non-skin sides of the side sheets 8L and 8R and the top sheet 7. The side sheets 8L and 8R are also fixed to the top sheet 7 by the fixing parts 31L and 31R.

[0050] Here, no non-adhesive regions are provided between the fixing parts 31L and 31R, between the top sheet 7 and the absorber 6, and between the top sheet 7 and the waist sheets 9F and 9R. The interlayer means between each sheet. On the non-skin side of the fixing parts 31L and 31R, the top sheet 7 is adhered to the absorber 6, and the top sheet 7 is adhered to the waist sheets 9F and 9R. The rigidity of the longitudinal end sides of the absorber 6 is increased by the fixing parts 31L and 31R. Also, since the fixing parts 31L and 31R are arranged across the waist sheet 9F having no shrinkage force, the shrinkage of the absorber 6 is suppressed on the front body region 1F side. Therefore, it is possible to suppress the falling off of the SAP particles from the first SAP layer 6A and the second SAP layer 6B on the front side of the absorber 6. Further, even when the fixing parts 31L and 31R are arranged across the waist sheet 9R having shrinkage force, the rigidity of the absorber 6 on the rear body region 1R side can be increased, so that it is possible to suppress the sagging of the rear end of the absorber 6. Note that the fixing parts 31L and 31R are preferably formed by overlapping the absorber 6 on the end sides in the width direction of the absorber 6 in order to suppress the sagging of the absorber 6.

[0051] Even if the SAP particles leak outside the folding lines 30L and 30R and the SAP particles enter between the side sheets 8L and 8R and the top sheet 7 or the back sheet 5, this SAP can be contained in the SAP accommodation space, and the waist sheets 9F and 9R can prevent the SAP particles from leaking to the outside.

[0052] Figure 9 is a diagram showing an overview of the SAP fixation rate test. Figure 9 is a device for examining to what extent SAP particles are fixed to the absorber 6. A pole stands vertically from the base 32, and a guide rail 31 with a length of 10 cm is installed vertically above the pole. Inside the guide rail 31, a dropping rod 30 is arranged. When the experimenter lifts the dropping rod 30 to the upper end of the guide rail 31 and releases the hand, the dropping rod 30 freely falls 10 cm along the guide rail 31 and stops at the lower end of the guide rail.

[0053] The absorber 6 cut into two pieces at the central part in the longitudinal direction is arranged on the dropping rod 30. Immediately below the dropping rod 30, an electronic balance 33 for weighing the dropped SAP particles is provided. Among the SAP particles contained in the absorber 6 that are not fixed, they fall from the absorber 6 to the electronic balance 33 due to the impact of the fall. In this state, the dropping operation is repeated 20 times to weigh the unfixed SAP particles. When the amount of the dropped SAP is DR and the amount of the SAP formulated in the absorber 6 in design is DF, the fixation rate (%) of the SAP can be obtained by the formula (1 - DR / DF) × 100.

[0054] Figure 10 is a diagram showing another example of the SAP fixation rate test. The overview of the test apparatus and the test method are the same as those shown in Figure 9. However, in the example shown in Figure 10, the absorber 6 is arranged in the test apparatus in a state covered with a resin bag 34. The bag 34 is made of polyethylene, for example. In the example shown in Figure 9, the SAP particles separated from the absorber 6 due to the impact of the fall of the dropping rod 30 accumulate at the bottom of the bag 34 instead of the electronic balance 33. Then, after the completion of the 20 dropping operations, the contents of the bag 34 are weighed with a separately prepared electronic balance to obtain the amount of the unfixed SAP particles.

[0055] In the experimental method shown in FIG. 10, the absorber 6 is covered with the bag 34. Although the SAP particles may scatter to locations other than under the experimental apparatus due to the impact of falling, covering the absorber 6 with the bag 34 enables the scattered SAP particles to be surely captured, and the amount of SAP particles not fixed to the absorber 6 can be measured more accurately. The content of the calculation formula for the fixing rate (%) of SAP is the same as that described above.

[0056] As a result of this experiment, the fixing rate of the SAP particles was 97%. It can be seen that even in the absorber 6 containing SAP particles at a content ratio that cannot be fixed by the short fibers due to the crushed SAP particles biting into the base layer 6I, the SAP particles can be sufficiently fixed.

[0057] FIG. 11 is a diagram showing a method for manufacturing an absorber according to an embodiment. The manufacturing process proceeds from FIG. 11(A) to FIG. 11(D). In FIG. 11(A), first, the lower core wrap sheet 6WB, which is a core wrap sheet for forming the other surface of the absorber 6, is disposed, and on the lower core wrap sheet 6WB, the base layer 6I composed of fibers is disposed. This process corresponds to the base layer placing process referred to in the present application. In FIG. 11(B), the first SAP layer 6A is disposed on the base layer 6I. At this time, the first SAP layer 6A contains the SAP particles constituting the second SAP layer 6B. This process corresponds to the SAP placing process referred to in the present application. In FIG. 11(C), the upper core wrap sheet 6WA, which is a core wrap sheet for forming one surface of the absorber 6, is disposed on the first SAP layer 6A. This process corresponds to the covering process referred to in the present application.

[0058] In Fig. 11(D), for the completed laminate, a press roll is used to press the upper surface of the upper core wrap sheet 6WA and the bottom surface of the lower core wrap sheet 6WB. At this time, among the SAP particles contained in the first SAP layer 6A, those with a small particle diameter that can pass through the fibers of the base layer 6I pass through the base layer 6I due to the pressing force and form a second SAP layer 6B between the base layer 6I and the lower core wrap sheet 6WB. This process corresponds to the pressing process in the present application. Fig. 11(E) is a cross-sectional view showing the structure of the absorber 6 manufactured by these processes. By going through such a process, an absorber 6 having a first SAP layer 6A with a large particle diameter and a second SAP layer 6B containing SAP particles having a smaller particle diameter than the SAP particles contained in the first SAP layer can be manufactured.

[0059] Fig. 12 is a view of the pressing process seen from the side. The completed laminate advances toward the press roll R and is pressed by the press roll R. Fig. 12(A) shows a state where the laminate is advancing toward the press roll R. Fig. 12(B) shows a state where the laminate is pressed by the press roll R and has passed through the press roll R. Among the SAP particles contained in the first SAP layer 6A, those with a small particle diameter that can pass through the fibers of the base layer 6I pass through the base layer 6I due to the pressing of the press roll when passing through the press roll. These SAP particles with a small particle diameter form the second SAP layer 6B. Note that the pressing does not necessarily have to be performed by a press roll and may be realized by sandwiching between press plates.

[0060] The fiber interstice size of the base layer 6I is 330 μm to 390 μm as described above. When observing the particle diameter of SAP particles suitable for such manufacturing, the average particle diameter was 320 μm to 380 μm. When using SAP particles with such a particle diameter, it can be said that the SAP particles are likely to bite into and be fixed to the base layer, and a part of them is likely to move from the first SAP layer 6A to the second SAP layer 6B under the pressure of the press roll.

[0061] <Second Embodiment> Next, a second embodiment will be described. FIG. 13 is a diagram showing an absorbent pad according to the second embodiment. In the first embodiment, the absorber 6 was incorporated into a tape-type disposable diaper. In contrast, the absorbent pad 40 shown in the second embodiment is obtained by incorporating the absorber 6 into an absorbent pad to be disposed between the diaper and the skin surface of the wearer. The absorbent pad 40 is used to absorb exudate by being disposed between the diaper and the skin surface of the wearer, thereby reducing the frequency of diaper changes.

[0062] The absorbent pad 40 has a structure in which both sides in the thickness direction of the absorber 6 are sandwiched by a water-permeable top sheet 7. Also, the absorbent pad 40 does not have a back sheet. For this reason, the absorbent pad 40 can absorb exudate from both sides in the thickness direction. It is preferable to use a core wrap sheet 6W that is excellent in liquid permeability in both directions.

[0063] As already described, the absorber 6 includes a first SAP layer 6A and a second SAP layer 6B with a base layer 6I interposed therebetween. Also, the particle diameter of the SAP particles constituting the first SAP layer 6A is larger than the particle diameter of the SAP particles constituting the second SAP layer 6B. For this reason, the absorption performance changes depending on whether the first SAP layer 6A side or the second SAP layer 6B side is disposed on the skin surface side. When the first SAP layer, which is one side, is disposed on the skin surface side, the SAP particles on the second SAP layer side, which is the non-skin surface side, absorb the exudate first. Even if a strong pressure is applied to the absorbent pad 40 in this state, the flow of the exudate to the skin surface side is inhibited by the base layer 6I and the first SAP layer 6A, so that backflow can be suppressed and a comfortable absorbent pad 40 can be realized.

[0064] On the other hand, when the second SAP layer, which is the other side, is disposed on the skin surface side, since the particle diameter of the SAP particles constituting the second SAP layer is small, the gaps between the particles are maintained even when the SAP particles absorb moisture. For this reason, even if the absorber 6 repeatedly absorbs exudate, a so-called gel blocking phenomenon does not occur, and the absorption performance can be maintained for a long time.

[0065] In this way, the absorbent pad 40 according to the present embodiment can obtain different absorption performances by making the surface on the skin side selectable, and the wearer or caregiver can select which absorption performance to prioritize. Therefore, on each absorption surface of the absorbent pad 40, characteristics when liquid is injected into the absorption surface are displayed. In the example shown in FIG. 13, on the top sheet 7 which is the outermost surface on the side of the first SAP layer 6A, since backflow can be suppressed, the character 6FA of "comfortable" is displayed. On the top sheet 7 which is the outermost surface on the side of the second SAP layer 6B, since the flow of the discharged liquid is not inhibited even when the repeatedly discharged liquid flows in and absorption can continue, the character 6FB of "long time" is displayed. Note that the characters 6FA and 6FB are not limited to this and may be other expressions. For example, they may be expressions imaging the effects or various figures imaging the effects. Further, the color of the top sheet 7 constituting the outermost side of each surface may be changed in combination with the display. The display method is not particularly limited, and for example, it may be by embossing or thermal embossing, or it may be by printing.

[0066] In this way, by disposing each surface with the respective surface on the skin side and displaying the characteristics when moisture is injected, the wearer or caregiver can easily identify what characteristics the surface has. And the wearer or caregiver can easily select which surface having which characteristics to dispose on the skin side.

[0067] Although each embodiment has been described above, the content of the present invention is not limited to the above embodiments. In the above embodiments, a tape-type disposable diaper and an absorbent pad have been described as examples, but the present invention is not limited to this, and the present invention is also applicable to absorbent articles such as pants-type disposable diapers.

[0068] The features included in each of the embodiments disclosed above can be combined with each other.

Explanation of Reference Numerals

[0069] 1 ··· Diaper 1B ·· Crotch area 1F ·· Front body area 1R ·· Rear body area 2L, 2R ·· Elastic body 3BL, 3BR ·· Leakage prevention wall 4 ·· Cover sheet 5 ·· Back sheet 6 ·· Absorbent body 6A ·· First SAP layer 6B ·· Second SAP layer 6C ·· Absorbent core 6FA ·· Character 6FB ·· Character 6W ·· Core wrap sheet 6WA ·· Upper core wrap sheet 6WB ·· Lower core wrap sheet 7 ·· Top sheet 8L, 8R ·· Side sheet 30 ·· Movable bar 31 ·· Guide rail 32 ·· Test bench 33 ·· Electronic balance 34 ·· Bag 40 ·· Absorbent pad SAP ·· SAP

Claims

1. A first liquid-permeable sheet that forms one surface of the absorber and has liquid permeability, A first SAP layer containing SAP particles that are superabsorbent polymers, A sheet-like base layer having liquid permeability, A second SAP layer containing SAP particles that are of the same component and the same manufacturing method as the SAP particles contained in the first SAP layer, and whose value obtained by dividing the surface area by the volume is different from that of the SAP particles contained in the first SAP layer, A second liquid-permeable sheet that forms the other surface of the absorber and has liquid permeability, Are laminated in the thickness direction, Absorber.

2. The absorber according to claim 1, wherein characteristics when water is injected from each surface are displayed on the outermost sides of the one surface and the other surface. The absorber according to claim 1.

3. The absorber according to claim 1, wherein the SAP particles constituting the first SAP layer and the SAP particles constituting the second SAP layer are formed of the same material. The absorber according to claim 1.

4. The absorber according to claim 1, wherein the SAP particles contained in the first SAP layer and the second SAP layer are of a crushed type, The base layer is a fiber sheet. The absorber according to claim 1.

5. The fiber interstice size of the base layer is 330 μm to 390 μm, The average particle diameter of the SAP particles contained in the first SAP layer is 381 μm to 450 μm, The average particle diameter of the SAP particles contained in the second SAP layer is 280 μm to 380 μm, The absorber according to any one of claims 1 to 4.

6. The absorber according to any one of claims 1 to 4, wherein the base layer is formed of synthetic fibers. The absorber according to any one of claims 1 to 4.

7. An absorbent article having the absorber according to any one of claims 1 to 4. Absorbent article.

8. A base layer placing step of placing a base layer composed of fibers on a second liquid-permeable sheet having liquid permeability, A SAP placing step of placing SAP particles on the base layer, A covering step of placing a first liquid-permeable sheet having liquid permeability on the SAP particles, A pressing step of applying pressure between the second liquid-permeable sheet and the first liquid-permeable sheet, A method for manufacturing an absorber, including.

9. The method for manufacturing an absorber according to claim 8, wherein the base layer is a fiber sheet having a fiber interstice size of 330 μm to 390 μm, The average particle diameter of the SAP particles is 320 μm to 380 μm. The method for manufacturing an absorber according to claim 8.

10. The method for manufacturing an absorber according to claim 9, wherein the SAP particles are of a crushed type. The method for manufacturing an absorber according to claim 9.

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