JP6838015B2 - Absorbent article - Google Patents

Description

The present invention relates to absorbent articles, and more particularly to absorbent articles such as light incontinence pads, pantyliners, sanitary napkins, vaginal discharge pads, urine absorbing pads, and disposable diapers for adults and children.

Conventionally, an absorbent article including a liquid-permeable front surface sheet, a liquid-impermeable back surface sheet, and an absorber interposed between the front and back sheets is known. For example, Patent Document 1 discloses an absorbent article comprising an absorber containing wood pulp fibers that have not been delignin-treated.

Japanese Unexamined Patent Publication No. 56-53745

In the absorbent article disclosed in Patent Document 1, since the wood pulp fiber contained in the absorber is not delignin-treated, the wood pulp fiber has a natural color derived from natural wood, and the absorber is a surface sheet. When viewed through through, it is possible to give the wearer or the like the impression that the product is made of natural materials and is gentle on the skin and highly natural-oriented.

However, of the cellulose, hemicellulose, and lignin components mainly contained in wood or non-wood pulp, the cellulose component is highly hydrophilic, whereas lignin is low in hydrophilicity and can be said to be hydrophobic. Therefore, the pulp fibers that have not been delignin-treated are highly hydrophobic, and when the pulp fibers are distributed throughout the absorber, the body fluid cannot be drawn into the inside from the surface of the absorber to be absorbed and retained. ..

An object of the present invention is to provide an absorbent article which is an improvement of the conventional invention and has an absorbent body which has the natural color of wood and can quickly absorb and retain body fluid.

The present invention has a thickness direction, a liquid-permeable front sheet located on the skin-facing surface side, a liquid-impermeable back sheet located on the non-skin-facing surface side, and the front surface sheet and the back surface sheet. With respect to an absorbent article including an absorber located between and.

In the absorbent article according to the present invention, the absorber has a liquid-absorbent core and a core cover sheet that covers at least the skin-facing surface side of the liquid-absorbent core, and the core cover sheet is the same. It has a first coating portion that covers the skin-facing surface side of the liquid-absorbent core, and the first coating portion and the surface sheet are joined to each other via an adhesive, and the core cover sheet and the suction-absorbing core are bonded to each other. Each of the liquid cores contains pulp fibers, and the content of the lignin component due to the pulp fibers in the core cover sheet is higher than the content of the lignin component due to the pulp fibers in the liquid absorbent core, and the core cover. The sheet has a lignin component content of 2-10% and is characterized by having a plurality of concave portions continuously extending from at least the surface sheet to a part of the liquid absorbing core in the thickness direction. To do.

The absorbent article according to the present invention includes the following embodiments.
(1) The core cover sheet further has a second coating portion that covers the non-skin facing surface side of the liquid absorbing core, and the second coating portion and the back surface sheet are attached to each other via an adhesive. Be joined.
(2) The concave portion has a bottom, and a part of the surface sheet, the core cover sheet, and the liquid absorbing core is compressed, and the thin portion where the concave portion is located is the concave portion. The density is higher than that of the thick part where is not located.
(3) The concave portion is an opening that penetrates the surface sheet and the absorber in the thickness direction.
(4) The adhesive is a SIS-based hot melt adhesive.
(5) The core cover sheet has a plurality of high lignin regions in which the content of the lignin component is higher than that in the peripheral region and is scattered in a plan view.
(6) The crepe rate of the core cover sheet is 7 to 20%, and the formation index is 50 to 300.
(7) The surface sheet has a first portion and a second portion having a denser fiber density than the first portion, and the first portion is joined to the high lignin region to form the first portion. Two parts are joined to the peripheral area.
(8) The surface sheet has a multi-layer structure, and the layer located on the skin-facing surface side is mainly composed of cotton fibers.
( 9 ) The Krem water absorption of the surface sheet is lower than the Krem water absorption of the core cover sheet.

In at least one embodiment of the absorbent article according to the present invention, since the core cover sheet contains a relatively large amount of lignin component, it has a natural color derived from a natural material such as wood and has a surface in the thickness direction. Since it has a plurality of concave portions that continuously extend from the sheet to a part of the liquid absorbing core, it is possible to quickly absorb and retain the body fluid.

The drawings show specific embodiments of the invention and include not only the essential configurations of the invention, but also selective and preferred embodiments.
The plan view of the sanitary napkin in the 1st Embodiment of the absorbent article which concerns on this invention is seen from the surface side. Top view of the sanitary napkin as seen from the back side. Top view of the absorber. FIG. 3 is a sectional view taken along line IV of FIG. FIG. 4 is a cross-sectional view similar to FIG. 4 in an example of a modified example of the absorber. The plan view of the absorber of the sanitary napkin according to the 2nd Embodiment. A partially enlarged view of the area surrounded by the VII line in FIG. FIG. 4 is a cross-sectional view similar to FIG. 4 of the sanitary napkin according to the second embodiment. The plan view of the absorbent article which concerns on 3rd Embodiment.

<First Embodiment>
The following embodiments include selective and preferred configurations as well as essential configurations of the invention with respect to the absorbent articles shown in the accompanying drawings. Hereinafter, embodiments of a sanitary napkin 10, which is an example of an absorbent article according to the present invention, will be described with reference to the accompanying drawings. The sanitary napkin 10 has a vertical direction Y, a horizontal direction X, and a thickness direction Z.

Referring to FIGS. 1 to 3, the sanitary napkin 10 has a vertical center line P that bisects the dimension in the width direction and a horizontal center line Q that bisects the dimension in the length dimension thereof. Convex on the facing surface (inner surface) 2 side and the non-skin facing surface (outer surface) 3 side on the opposite side, the convex first and second edge edges 10a and 10b, and the central portion where the lateral center line Q is located. The first and second side edges 10c and 10d to be bent, the liquid-permeable front sheet 11 located on the skin-facing surface side, and the impermeable back sheet 12 located on the non-skin-facing surface side, both of these. Includes a liquid-absorbing absorber 20 located between the sheets 11 and 12. The surface sheet 11 and the absorber 20 are joined to each other by a known joining means such as a hot melt adhesive to form a liquid absorbing layer 13.

Although not shown, an intermediate sheet made of a relatively bulky fibrous non-woven fabric may be arranged between the surface sheet 11 and the absorber 20 in order to improve the flexibility of the sanitary napkin 10. Further, in order to suppress leakage of body fluid between the absorber 20 and the back surface sheet 12, a leak-proof sheet made of a liquid-impermeable fibrous non-woven fabric or a plastic film, which is preferably breathable, may be arranged. Good.

The absorber 20 extends in the longitudinal direction between the first edge 20a facing the first edge 10a, the second edge 20b facing the second edge 10b, and the first and second edge 20a, 20b. It has first and second side edges 20c and 20d. The front and back sheets 11 and 12 extend outward from the outer circumference of the absorber 20, and on the skin-facing surface side of the front sheet 11, a pair of side sheets extending in the vertical direction Y so as to face each other in the horizontal direction. 14 is arranged. The pair of side sheets 14 are joined to the surface sheet 11 via a side joint (not shown). Although not shown, an elastic material extending in the vertical direction Y may be arranged on the side sheet 14 so as to be contractible in the extended state in order to form a leak-proof wall that stands up to the body side in the worn state. Further, the side joint portion for fixing the side sheet 14 may be a seal line extending in the vertical direction Y having a design element such as a floral pattern or a geometric pattern.

The sanitary napkin 10 is formed from the front surface sheet 11, the back surface sheet 12, and the side sheet 14, and both ends extending in the lateral direction X outside the first and second edge portions 20a and 20b of the absorber 20 in the longitudinal direction Y. It has 16 and both side edges 17 extending in the vertical direction Y outside the first and second side edges 20c and 20d of the absorber 20 in the lateral direction X. At the central portion of the sanitary napkin 10 in the vertical direction Y, a wing portion 18 formed by a part of both side edge portions 17 which is convex outward in the horizontal direction X is located. The sheet 11, 12 and 14 which are stacked with each other, are joined together via the seal portion 19 located along the outer periphery of the sanitary napkin 10.

Referring to FIG. 2, a plurality of fastening regions 30 are arranged on the back surface side of the sanitary napkin 10. The plurality of fastening regions 30 are for fastening the sanitary napkin 10 to clothing such as underwear, and are formed of a plurality of line-shaped adhesives or pressure-sensitive adhesives extending in the vertical direction Y. Will be done. The anchoring region 30 has a central region 31 extending in the vertical direction Y in a region overlapping the absorber 20 and a side region 32 located in the wing portion 18. The anchorage area 30 is covered with a separator (not shown) made of a plastic film.

The surface sheet 11 can be formed from various liquid-permeable fibrous non-woven fabrics, for example, an air-through fibrous non-woven fabric having a mass of about 15 to 45 g / m ² , a porous plastic film, and a laminate sheet thereof. The back sheet 12 can be formed from a liquid-impermeable and moisture-permeable plastic film, a liquid-impermeable fibrous non-woven fabric, a laminated sheet thereof, and the like. As the side sheet 14, the same sheet material as the surface sheet 11 can be used. However, in order to effectively prevent lateral leakage of body fluid, it is preferable to use a sheet material having hydrophobicity or water repellency.

As the surface sheet 11, a sheet having an uneven surface side can also be used. The surface of the sheet is formed of a plurality of concave portions and a plurality of convex portions alternately arranged in the vertical direction Y or the horizontal direction X, and as a method for forming the plurality of convex portions and the concave portions. For example, a method of forming a bulky portion and a bulky portion by controlling the amount of fibers, a method of forming a concave portion by embossing / debossing, a method of shaping into an uneven shape, and the like can be considered. The fibers of the convex portion and the concave portion are arranged so that one is sparse and the other is dense so that the fiber densities are different from each other. The joint strength is increased by joining the portion where the fibers are sparsely arranged (first portion) and the high lignin region 52 of the core cover sheet 22 described later, while the portion where the fibers are densely arranged (the first portion). By joining the two portions) and the low lignin region 51, the liquid absorption property can be further enhanced.

Further, even when menstrual blood is repeatedly excreted in a relatively short time, by temporarily collecting menstrual blood in the recess, the surface of the surface sheet 11 and between the surface sheet 11 and the core cover sheet 22 It is possible to prevent menstrual blood from leaking sideways. Further, it is preferable that a part of the recesses of the surface sheet 11 is substantially (continuously or discontinuously) surrounded by a squeezed portion forming a squeezed groove, a compressed recess formed by embossing, or the like. .. In such a case, it is possible to prevent the body fluid accumulated in the recess from leaking in the horizontal direction X and the vertical direction Y. In addition, when the surface of the surface sheet is uneven, the light brown core cover sheet 22 is visually recognized darker in the concave portion than in the convex portion in the surface view, so that a decorative effect due to the color gradation is produced. ..

The outer peripheral sealing portion 19 can be bonded by an adhesive, ultrasonic welding, heat welding, laser welding, high frequency welding or the like by known welding means, or by embossing alone or in combination. Further, the sheets 11, 12, and 14 laminated in the thickness direction Z are joined to each other via an adhesive such as a hot melt adhesive. Examples of the hot melt adhesive coating method include various known coating methods such as spiral coating, coater coating, curtain coater coating, and spray coating.

With reference to FIGS. 3 and 4, the absorber 20 is a liquid absorbing core 21 formed by mixing superabsorbent polymer particles (SAP) and cellulosic fibers such as fluff wood pulp and rayon fiber into a predetermined shape. And a liquid-permeable core cover sheet 22 that covers the entire liquid-absorbing core 21 in order to improve its shape retention and liquid diffusivity.

The dimension of the core cover sheet 22 in the vertical direction Y is larger than the dimension of the liquid absorbing core in the vertical direction Y, and the side edge portions 22a and 22b of the core cover sheet 22 absorb the entire liquid absorbing core 21. The liquid core 21 is located so as to overlap each other on the bottom surface side in the central portion in the lateral direction X. By folding both side edge portions 22a and 22b together, a superposed portion 23 in which both side edge portions 22a and 22b extending in the vertical direction are laminated with each other is formed in the central portion of the absorber 20 in the lateral direction X. To.

The core cover sheet 22 has a first covering portion 25 that covers the skin facing surface side of the liquid absorbing core 21, and a second covering portion 26 that covers the non-skin facing surface side of the liquid absorbing core 21. In the present embodiment, the core cover sheet 22 is formed of one continuous sheet, but the first core cover sheet forming the first covering portion 25 and the first core cover sheet are separate bodies. , May be composed of a second core cover sheet forming the second covering portion 26.

The core cover sheet 22 is formed of various known fibrous nonwoven fabrics or tissues, and is mainly composed of pulp fibers. The pulp fibers of the core cover sheet 22 include bleached pulp fibers that have been delignin-treated and unbleached pulp fibers that have not been delignin-treated. Here, the pulp fiber includes a non-wood pulp fiber made of linter, Manila hemp, kenaf, straw, bamboo, and banana as a raw material, in addition to a wood pulp fiber obtained from a coniferous tree or a broadleaf tree as a raw material.

Further, the core cover sheet 22 has, for example, a first layer (upper layer or lower layer) composed of regenerated cellulose fibers such as rayon fibers and hydrophilic fibers such as semi-synthetic cellulose fibers, and unbleached unbleached without delignin treatment. It may have a multi-layer structure composed of a second layer (lower layer or upper layer) composed of pulp fibers 42. In such a case, as described later, even when the second layer has a sea-island structure composed of a low lignin region 51 and a high lignin region 52 described later, the body fluid can be sufficiently diffused in the first layer. Therefore, uneven diffusion of body fluid in the entire core cover sheet 22 can be suppressed. Thereby, even after absorption of body fluids over a plurality of times, it is possible to suppress a decrease in the bonding strength between the topsheet 11 can be maintained a suitable absorbent.

Since the core cover sheet 22 has unbleached pulp fibers, it has a light brown color (wood color) derived from a plant material such as wood as a whole. Since the sheets 11, 12, and 14 other than the core cover sheet have an overall white color by kneading a white pigment such as titanium dioxide into the constituent fibers, the core cover sheet 22 is the sanitary napkin 10. In front view and / or back view, it is easily visible through the other sheets 11, 12, and 14.

Pulp fibers are generally subjected to a cooking step (first step of delignin treatment) in which a chemical is added to the raw material chips and boiled at high temperature and high pressure to evaporate lignin after the raw material chip processing step. By going through a screen process to remove foreign substances, an oxygen exposure process to decompose lignin remaining in the cooking process with oxygen (second stage of lignin treatment), and a bleaching process to bleach pulp using multiple types of chemicals. It becomes bleached bleached pulp fiber. Of these steps, the unbleached pulp fiber has undergone only the cooking step and the screen step, which are the first steps of the delignin treatment, and has been subjected to a certain degree of delignin treatment.

The lignin content of the unbleached pulp fibers contained in the core cover sheet 22 is 0.2 to 10.0%.

The lignin content with the unbleached pulp fiber was measured by the following method.

<Measurement method of lignin content>
ADF Quantitative Reagent: Acid Detergent Solution 10 g of cetyltrimethylammonium bromide (hexadecyltrimethylammonium bromide) dissolved in 500 mL of 1N sulfuric acid.
acetone
Decahydronaphthalene as an antifoaming agent (optional)
<Measurement procedure>
300 g of the sample was weighed, placed in a 50 mL Erlenmeyer flask, and 30 mL of acidic dadgen and solution were added. The lid was covered with aluminum foil, and the Erlenmeyer flask was placed in boiling water and decomposed for 60 minutes. After disassembly, it was transferred to a goochill pot lined with glass fiber filter paper (GA-200), suction-filtered, and the residue was washed with hot water and acetone. After air drying, it was heat dried. The weight of ADF is the weight obtained by constant weight after drying and subtracting the ash content, but the ash content after lignin quantification cannot be used for this.

Lignin Quantitative Reagent: 72% Sulfuric Acid <Measurement Procedure>
After adding a few drops of 72% sulfuric acid to the above-dried goochill pot to moisten the whole, about twice the amount of ADF was added to the sulfuric acid, and the mixture was left to stand for 3-4 hours with appropriate addition of sulfuric acid every hour. Then, it was suction-filtered and washed with hot water until the furnace liquid became no longer acidic. After air-drying, heat-dry and constant volume. The guchill pot was incinerated at 550 ° C. to determine the ash content.

Since the core cover sheet 22 has unbleached pulp fibers, the core cover sheet 22 has a light brown color derived from a plant material in terms of surface appearance as compared with the case of using a core cover sheet made of only bleached pulp fibers, and is worn by the wearer or worn. It can give the assistant the image that it is a skin-friendly product using natural materials. Further, since the core cover sheet 22 has a light brown color, the redness of the menstrual blood is suppressed when the excreted menstrual blood permeates the surface sheet 11 and is absorbed and retained by the absorber 20. As a result, it is possible to suppress the disgust caused by directly visually recognizing menstrual blood, and to alleviate the mental anxiety caused by visually recognizing the redness of menstrual blood, for example, for the wearer in the early stage of menstruation. .. In addition, since the lignin component has an antibacterial effect, it is possible to suppress the growth of various germs after use and dispose of it hygienically.

In order for the core cover sheet 22 to exhibit such a natural appearance, suppression of redness of menstrual blood, and a certain antibacterial effect, the content of the lignin component of the core cover sheet 22 must be 2-10%. preferable. When the content of the lignin component of the core cover sheet 22 is less than 2%, the light brown color of the core cover sheet 22 becomes so thin that it is visually indistinguishable from the other sheets 11, 12, and 14 having white color. There is a risk. On the other hand, when the content of the lignin component in the core cover sheet 22 exceeds 10%, the color due to the lignin component may become darker, which may impair the natural appearance of the natural material and the redness of menstrual blood. It may be difficult to see and the amount of menstrual blood may not be accurately grasped.

Referring to FIGS. 3 and 4 , the liquid absorbing layer 13 is located between the first and second end regions 13A and 13B facing each other in the vertical direction Y and the first end region 13A and the second end region 13B. It has an intermediate region 13C and the like. The liquid absorbing layer 13 further includes a plurality of concave portions 60 that are concave from the front surface sheet 11 toward the back surface sheet 12, and a squeezed groove 70 that extends discontinuously in an annular shape so as to surround the plurality of concave portions 60. Have.

The squeezed groove 70 includes a curved first outer groove 71 located in the first end region 13A, a curved second outer groove 72 located in the second end region 13B, and a first outer groove 71. The third outer shell groove 73 located in the intermediate region 13C between the second outer shell groove 72 and the second outer shell groove 72, the first inner shell groove 74 located in the first outer shell groove 71, and the second outer shell groove It has a second inner groove groove 75 located in the groove 72.

The concave portion 60 has a bottom and continuously extends from the surface sheet 11 to a part of the liquid absorbing core 21, and is located apart from each other in the vertical direction Y and the horizontal direction X in a plan view. There is. The concave portion 60 includes a first concave portion 60a located in an area surrounded by the first and second inner groove grooves 74 and 75 and the third outer groove groove 73, and the first outer groove groove 71 and the first inner portion. The second concave portion 60b arranged in the area surrounded by the groove 74, and the third concave portion 60c arranged in the area surrounded by the second outer groove 72 and the second inner groove 75. And have.

The first concave portion 60a has a substantially circular shape, whereas the second and third concave portions 60b and 60c have a substantially cross shape unlike the first concave portion 60a. The first concave portion 60a is arranged more densely than the second and third concave portions 60b and 60c. The concave portion 60 may have various known shapes such as a circle, an ellipse, a triangle, and a rectangle in addition to the illustrated embodiment. As various dimensions of the first concave portion 60a, for example, when it has a substantially circular shape, the diameter is 1.0 to 1.5 mm, the pitch in the horizontal direction X is 3.0 to 5.0 mm, and the pitch in the vertical direction Y is Y. The pitch is 5.0 to 7.0 mm. Here, the pitch means the distance between the center points of the first concave portion 60a.

By forming the plurality of concave portions 60 in the liquid absorbing layer 13, it is possible to suppress twisting and deformation of the absorber 20 during wearing. In particular, since the region where the first concave portion 60a is arranged is a portion of the absorber 20 that faces the excretion port of the wearer and is thicker than the other regions, the first concave portion 60a should be arranged. This can increase the rigidity and effectively prevent twisting and deformation during wearing. Further, by forming the squeezed groove 70 extending in a ring shape in the vertical direction Y in the entire area of the absorber 20, the body fluid can be rapidly diffused through the squeezed groove 70, and the absorber 20 can be spread on the body. It can be deformed into a curved shape as a whole along the shape.

The concave portion 60 of the liquid absorbing layer 13 can be formed, for example, by pressure heat treatment. Specifically, in a known embossing process, it can be formed by pressing a heated emboss spin from the surface sheet 11 side of the liquid absorbing layer 13 and compressing the absorber 20 together with the surface sheet 11.

Usually, the core cover sheet is preferably a hydrophilic sheet because it has a role of absorbing and diffusing body fluid that has permeated the surface sheet and transferring it to the liquid-absorbent core in addition to retaining the shape of the liquid-absorbent core. Although used, the unbleached pulp fibers contained in the core cover sheet 22 according to the present embodiment have a low degree of hydrophilicity and are hydrophobic because of the high content of the lignin component, and menstrual blood that has permeated the surface sheet 11. Cannot be sufficiently absorbed and retained, and cannot be rapidly transferred to the liquid absorbing core 21.

In the present embodiment, by having a plurality of concave portions 60 extending to the inside of the liquid absorbing core 21, menstrual blood can be directly retained in the concave portions 60, via the surface sheet 11 and the core cover sheet 22. The surface area of the liquid-absorbent core 21 that indirectly contacts menstrual blood is increased, and the liquid-absorbent core 21 can rapidly absorb and retain body fluid via both sheets 11 and 22.

Since the core cover sheet 22 has unbleached pulp fibers and therefore has lower diffusivity than the core cover sheet made of ordinary tissue, the menstrual blood that has entered the concave portion 60 is not diffused and is not diffused. Since it is held at the bottom and the peripheral wall of the 60, the body fluid can be absorbed in a spot at the arrangement portion of the plurality of concave portions 60. Therefore, it is possible to prevent menstrual blood from adhering to the body through the side sheet 14 by diffusing the body fluid to both side edges of the liquid absorbing core 21.

Further, at the bonding interface between the surface sheet 11 and the core cover sheet 22 via the hot melt adhesive, the bleached pulp fibers may absorb menstrual blood and swell, and the bonded portion may peel off to reduce the bonding strength. is there. Since the unbleached pulp fiber is less hydrophilic and hydrophobic than the bleached pulp fiber 41, it absorbs menstrual blood and is difficult to swell, and the joint portion does not peel off. Therefore, since the core cover sheet 22 contains the bleached pulp fibers and the unbleached pulp fibers, it is possible to suppress the peeling and lifting of the surface sheet 11 during wearing. Further, when the amount of adhesive is increased in order to increase the bonding strength of both sheets 11 and 22, the sheet rigidity may increase and the flexibility and liquid permeability may decrease, but the content of unbleached pulp fibers It can be said that the joint strength can be controlled without causing such a disadvantage by adjusting the above.

The second covering portion 26 of the core cover sheet 22 is joined to the back surface sheet 12 via a hot melt adhesive. Since the core cover sheet 22 contains unbleached pulp fibers, the back surface sheet 12 and the core cover sheet 22 are joined via a hot melt adhesive as compared with the core cover sheet made of only bleached pulp fibers. It is difficult to peel off at the interface and has the required bonding strength. Therefore, it is not necessary to increase the mass of the hot melt adhesive in order to prevent the sheet from peeling off, and by increasing the mass of the hot melt adhesive, the rigidity of the sheet is increased and the followability to the absorber 20 is lowered. There is nothing to do.

The first coating portion 25 and the front surface sheet 11 of the core cover sheet 22, and the second coating portion 26 and the back surface sheet 12 are bonded to each other via a rubber-based adhesive, for example, a SIS-based hot melt adhesive. Is preferable. By joining the sheets 11, 12, and 22 to each other via a SIS-based adhesive, the volatile organic compound (VOC) value can be reduced as compared with an EVA resin-based adhesive or the like using an organic solvent. It can be used more gently on the skin and safely.

The thin portion (bottom of the concave portion 60) 61 of the absorber 20 where the concave portion 60 is located has a higher density than the thick portion 62 where the concave portion 60 located around the concave portion 60 is not located. .. Since the thin portion 61 where the concave portion 60 is located has a high density, menstrual blood that has entered the concave portion 60 is quickly absorbed and diffused by the thin portion 61.

The texture index of the core cover sheet 22 is preferably 50 to 300. If the texture index of the core cover sheet 22 is less than 50, the pulp fibers are densely and uniformly arranged, so that the liquid permeability is lowered, and menstrual blood cannot be rapidly transferred to the liquid-absorbing core 21. On the other hand, when the formation index exceeds 300, an extremely poor formation portion is formed, the tensile strength is lowered, and a part may be broken during use.

<Measurement method of formation index>
The formation index of the core cover sheet 22 was measured using a formation tester FMT-MIII manufactured by Nomura Shoji Co., Ltd. The measurement area was 250 mm × 180 mm, the measurement time was 3 seconds / sample, and the texture indexes on both surfaces of the three samples were measured, and the average value was used as the measured value. The formation index means that the smaller the measured value, the less the formation unevenness.

Since the unbleached pulp fiber has higher rigidity than the bleached pulp fiber, when the core cover sheet 22 is formed only from the unbleached pulp fiber, the flexibility becomes relatively low, and the surface sheet 11 has a relatively low flexibility. The core cover sheet may peel off from the surface sheet 11 because it cannot follow the movement, but the inclusion of the bleached pulp fiber does not significantly impair the flexibility. Therefore, the core cover sheet 22 has the required flexibility, and specifically, the crepe rate of the core cover sheet 22 is 7 to 20%. When the crepe ratio of the core cover sheet 22 is less than 7%, the rigidity of the core cover sheet 22 becomes relatively high and the movement of the surface sheet 11 cannot be followed. On the other hand, when the crepe ratio exceeds 20%, the core cover sheet 22 becomes too flexible, and there is a risk that the sheet may be torn during manufacturing or use.

<Measurement method of crepe rate>
The crepe ratio of the core cover sheet 22 was measured by the underwater elongation method. The core cover sheet 22 is cut into 100 mm × 100 mm to prepare a measurement sample, the measurement sample is immersed in water for 10 seconds and then pulled up, and the crepe rate is calculated from the amount of change in dimensions by the following formula. The measurement is performed three times (n = 3), and the average value is taken as the measured value.
Crepe rate (%) = {(dimensions after immersion in water) / (dimensions before immersion in water) -1} x 100

As the surface sheet 11, a hydrophilic sheet containing cotton fibers (including organic cotton) can be used. When such a sheet is used as the surface sheet 11, it is excellent in cushioning property, touch property and liquid absorption property. Further, by forming a liquid absorbing layer by the surface sheet 11 containing cotton fibers and the core cover sheet 22 having a high lignin region 52, the core cover sheet 22 has a relatively small liquid retention of the constituent fibers, while the surface surface. Since the sheet has high hygroscopicity, the moisture in the absorber 20 can be absorbed by the surface sheet 11. Thereby, the generation of moisture between the sanitary napkin and the body can be suppressed, and the internal stuffiness can be suppressed.

The Krem water absorption of the core cover sheet 22 is preferably higher than the Krem water absorption of the surface sheet 11 containing cotton fibers. Since the Krem water absorption of the core cover sheet 22 is higher than the Krem water absorption of the surface sheet 11 located on the skin facing surface side, the core cover sheet 22 draws in the menstrual blood absorbed and diffused in the surface sheet 11. It can be absorbed into the liquid absorbing core 21 and quickly transferred to the liquid absorbing core 21, and the liquid residue on the surface sheet 11 can be effectively suppressed.

<Measurement method of Krem water absorption>
The Krem water absorption of the core cover sheet 22 was measured in accordance with the Krem water absorption test (JIS-L1907, P8141). A ruler, a stopwatch, a plastic container, and artificial urine (colored with blue No. 1) were used as measuring instruments. A sheet cut from the core cover sheet 22 to a size of 25 mm in width and 150 mm in length was used as a sample (N = 3). First, artificial urine was placed in a plastic container until the depth of the artificial urine was 10 mm or more. Next, the collected test piece was fixed with a fixing chuck and set so as to be immersed in artificial urine at a depth of 5 mm from the tip of the sample. This was left as it was for 120 seconds (environment: temperature 20 ° C./humidity 60%). The artificial urine climbed up the sample, and the suction distance on the sample was measured from the surface of the artificial urine. The longer the suction distance, the higher the Krem water absorption.

Further, the surface sheet 11 may have a multi-layer structure, and in that case, it is preferable that the layer (upper layer) located on the skin-facing surface side is substantially formed of cotton fibers. In such a case, the cotton fiber can absorb moisture more efficiently in the portion close to the skin.

Further, the surface sheet 11 has a multi-layer structure, and the layer (upper layer) located on the skin facing surface side is mainly cotton fiber, and the layer (lower layer) located on the non-skin facing surface side is mainly hydrophobic synthetic resin fiber. It can also be formed from each. In such a case, although the surface sheet 11 contains water-absorbent cotton fibers on the skin side, the Krem water absorption of the surface sheet 11 is lower than the Krem water absorption of the core cover sheet 22. By lowering the Krem water absorption of the surface sheet 11 to the Krem water absorption of the core cover sheet 22, the core cover sheet 22 which is closer to the absorber 20 without diffusing the body fluid on the surface of the sanitary napkin 10 The body fluid can be diffused, and the body fluid absorbed by the absorber 20 can be prevented from returning to the surface side (rewetback).

As described above, the liquid-absorbent core 21 optionally has cellulosic fibers including semi-synthetic cellulose fibers such as acetate and regenerated cellulose fibers such as rayon, in addition to cellulosic fibers such as cotton and pulp fibers. Like the liquid-absorbent core 21, the core cover sheet 22 has a high affinity because it has cellulosic fibers composed of bleached pulp fibers and unbleached pulp fibers. When the core 21 and the core 21 are welded to each other, the bonding strength is improved.

Further, the liquid absorbing core 21 may be formed only from SAP particles. In such a case, the absorber 20 is composed of a liquid absorbing core 21 composed of only SAP particles and a core cover sheet 22 covering the liquid absorbing core 21. In such a case, the core cover sheet 22 has a low lignin region 51 described later, so that the liquid retention property is relatively low, while the liquid absorption core 21 is formed only of SAP particles having a high liquid absorption capacity. As a result, the absorber 20 as a whole can exhibit an appropriate liquid absorption property.

The liquid-absorbent core 21 may have a plurality of functional particles formed of activated carbon, zeolite, or the like and having a function of adsorbing an odor of a body fluid such as menstrual blood. Since the liquid-absorbent core 21 has an odor-adsorbing property, the sanitary napkin 10 can be used and disposed of more hygienically and cleanly in combination with the antibacterial property of the core cover sheet 22.

With reference to FIGS. 3 and 4 , a superposed portion 23 in which both side edge portions 22a and 22b of the core cover sheet 22 are laminated with each other is located at the central portion of the absorber 20 in the lateral direction X. Since the overlapping portion 23 is a portion where the core cover sheet 22 is folded, the light brown color due to the unbleached pulp fibers is visually recognized darker than the other portions of the absorber 20, and extends in the vertical direction Y in appearance. It can be a design accent as a line. Further, the line extending in the vertical direction Y can be regarded as a mark indicating the central portion of the absorber 20 and used for positioning when the sanitary napkin 10 is attached to underwear or the like. Further, even when the liquid-absorbent core 21 absorbs a large amount of menstrual blood and exudes menstrual blood from both end edges, hydrophobic unbleached pulp fibers are compared outside the longitudinal direction Y of both end edges. By locating the superposed portion 23 containing a large amount of blood, it is possible to effectively prevent menstrual blood from exuding outward from both side edges 20c and 20d of the absorber 20.

FIG. 5 is a cross-sectional view similar to FIG. 4 in an example of a modification of the absorber 20. In this modification, a plurality of concave portions 60 formed in the liquid absorbing layer 13 are formed from openings penetrating the surface sheet 11 and the absorber 20. Such an opening can be formed by hollowing out the entire thickness dimension of the liquid absorbing layer 13. Since the impermeable back sheet 12 is located on the bottom surface of the concave portion 60, the body fluid accumulated on the bottom surface does not leak to the outside and is absorbed and held by the absorber 20 from the peripheral wall of the opening. ..

<Second Embodiment>
6 is a plan view of the absorber 20 of the sanitary napkin 10 according to the second embodiment, FIG. 7 is a partially enlarged view of the region surrounded by the VII line of FIG. 6, and FIG. 8 is the second embodiment. It is the same cross-sectional view as FIG. 4 of the said sanitary napkin.

In the present embodiment, the first coating portion 25 of the core cover sheet 22 has a low lignin region (low lignin content region) 51 in which the content of the lignin component is relatively low, and a content of the lignin component higher than that of the low lignin region 51. Has a high lignin region (high lignin content region) 52. The low lignin region 51 is mainly formed by assembling bleached pulp fibers 41, and the high lignin region 52 is mainly formed by assembling unbleached pulp fibers 42. In the plan view of the first covering portion 25 of the core cover sheet 22, the low lignin region 51 is a peripheral region located in a relatively wide range on the outer surface of the core cover sheet 22, whereas the high lignin region 52 Are arranged so as to be scattered with respect to the low lignin region 51. Further, since it has such an arrangement mode, it can be said that the first covering portion 25 of the core cover sheet 22 has a sea-island structure in which the low lignin region 51 is the sea and the high lignin region 52 is an island.

The core cover sheet 22 according to the present embodiment is formed in the form of a sheet by entwining a mixture of bleached pulp fibers 41 and unbleached pulp fibers 42 in the papermaking process, and the low lignin region 51 is mainly formed. Since the bleached pulp fibers 41 and the high lignin region 52 are mainly formed by arranging the unbleached pulp fibers 42, the boundary between the two regions 51 and 52 is unclear and cannot be clearly distinguished. Further, as a method for forming the high lignin region 52 scatteredly in the low lignin region 51 on the entire outer surface of the core cover sheet 22, for example, a mixing method and a mixing ratio of the pulp fibers 41 and 42 are used. It is conceivable to appropriately adjust the transport speed of the transport conveyor at the time of manufacturing, the nozzle diameter when the pulp fibers 40 are deposited on the conveyor via the air injected from a plurality of nozzles, the air volume of the blown air, the wind speed, and the like. ..

Since both regions 51 and 52 are formed by adjusting various conditions in the manufacturing process, unbleached pulp fibers 42 are contained in a part of the low lignin region 51 and bleached pulp fibers 41 are contained in the high lignin region 52, respectively. It can be said that it may be done. Therefore, the low lignin region 51 and the high lignin region 52 are not formed only from the bleached pulp fiber 41 and the unbleached pulp fiber 42, respectively, and may also contain fibers other than the pulp fiber. For example, the content of the bleached pulp fiber 41 in the pulp fiber in the low lignin region 51 is 50 to 100%, and the content of the unbleached pulp fiber 42 in the pulp fiber in the high lignin region 52 is 50 to 100%.

Since the high lignin region 52 means a region in which the content of the lignin component is higher than the low lignin region 51, which is the peripheral region in the core cover sheet 22, the bleached pulp fiber 41 and the unbleached pulp fiber 42 are not used. Can also be formed. For example, a high lignin region 52 having a higher content of the lignin component than the peripheral region can be formed by infiltrating the liquid containing the lignin component into a fibrous nonwoven fabric sheet made of rayon fiber or synthetic fiber in a scattered manner.

Referring to FIG. 8, since the first covering portion 25 of the core cover sheet 22 has a low lignin region 51 and a plurality of high lignin regions 52 scattered around the low lignin region 51, both regions 51, 52 appear alternately in the lateral direction X. Since the high lignin region 52 is scattered in the low lignin region 51, the low lignin region 51 and the high lignin region 52 are alternately arranged not only in the horizontal direction X but also in the vertical direction Y. It can be said that there is.

As described above, in the cross-sectional view of the first covering portion 25, the low lignin region 51 and the high lignin region 52 are alternately located in the horizontal direction X and the vertical direction Y, so that the menstrual blood that has permeated the surface sheet 11 is hydrophilic. It can be absorbed in the low lignin region 51 of the above, and rapidly transferred to the liquid absorbing core 21 to be absorbed and retained, and has a required absorption rate.

Since the low lignin region 51 and the high lignin region 52 are formed by the bleached pulp fiber 41 and the unbleached pulp fiber 42, the shape of the boundary line between them is unclear, and at least in a plan view, the shape of the boundary line is unclear. It has a wavy shape that looks like a meander rather than a straight line. Therefore, the required absorption area can be maintained per unit width (for example, 1.0 mm) near the boundary between the low lignin region 51 and the high lignin region 52.

<Third Embodiment>
FIG. 9 is a plan view of the absorbent article according to the third embodiment of the present invention, and the absorber 20 is used for the disposable diaper (absorbent article) 80. The disposable diaper 80 is shown in a state in which the side seams joining the both side edges of the front and rear waist panels 84 and 85 are peeled off and extended in the horizontal and vertical directions.

The disposable diaper 80 has a front waist area 81, a rear waist area 82, and a crotch area 83 located between the front and rear waist areas 81 and 82. Further, the diaper 80 includes a front waist panel 84 that defines a part of the front waist area 81 and a crotch area 83, a rear waist panel 85 that defines a part of the rear waist area 82 and the crotch area 83, and a front and rear waist. A liquid absorbing structure 86 extending in the vertical direction is provided on the skin facing surface side of the panels 84 and 85, and the front and rear waist panels 84 and 85 are spaced apart from each other in the vertical direction in a state where both side edges thereof are overlapped with each other. A waist opening and a pair of leg openings are defined by being joined to each other via a plurality of arranged seams. The absorber 20 extends from the crotch region 83 to the front and rear waist regions 81 and 82 in the liquid absorbing structure 86.

The diaper 80 is a so-called pants type in which both front and rear waist regions 81 and 82 are joined in advance, and like the sanitary napkin 10, the absorber 20 covers the liquid absorbing core 21 and the diaper 80. It is composed of a core cover sheet 22, and the core cover sheet 22 contains unbleached pulp fibers 42, and a plurality of concave portions 60 are formed in the liquid absorbing layer 13. The light brown color of the core cover sheet 22 is seen through the inside view and / or the outside view of the diaper 80, so that the absorber 20 gives a natural product image using a natural material, has excellent antibacterial properties, and urinates. Body fluids such as loose stools and loose stools can be rapidly transferred from the core cover sheet 22 to the liquid-absorbent core 21 via the plurality of concave portions 60. The absorbent article according to the present invention may be not only a pants-type diaper but also an open-type diaper.

In each embodiment, a separate sheet that is bulky and has excellent cushioning properties may be arranged between the surface sheet 11 and the core cover sheet 22. Since the separate sheet is joined to the surface sheet 11, it can be said that it is substantially a part of the surface sheet 11.

Unless otherwise specified, the constituent members of the absorbent articles 10 and 80 include various known materials commonly used in this field, in addition to the materials described herein. The material can be used without limitation. In addition, the terms "first" and "second" used in the present specification and the claims are used only for distinguishing similar elements, positions, and the like.

2 Skin facing surface 3 Non-skin facing surface 10 Sanitary napkin (absorbent article)
11 Front sheet 12 Back sheet 20 Absorber 21 Liquid-absorbent core 22 Core cover sheet 25 First coating 26 Second coating 40 Pulp fiber 41 Unbleached pulp fiber 42 Unbleached pulp fiber 51 Low lignin region 52 High lignin region 60 Concave Part 60a First concave part 60b Second concave part 60c Third concave part 80 Disposable diaper (absorbent article)

Claims (10)

Between the liquid-permeable front surface sheet having a thickness direction and located on the skin-facing surface side, the impermeable back sheet located on the non-skin-facing surface side, and the front surface sheet and the back surface sheet. In absorbent articles, including located absorbers,
The absorber has a liquid-absorbent core and a core cover sheet that covers at least the skin-facing surface side of the liquid-absorbent core.
The core cover sheet has a first covering portion that covers the skin-facing surface side of the liquid-absorbent core.
The first coating portion and the surface sheet are bonded to each other via an adhesive.
The core cover sheet and the liquid-absorbent core each contain pulp fibers and contain pulp fibers.
The content of the lignin component of the pulp fiber in the core cover sheet is higher than the content of the lignin component of the pulp fiber of the liquid absorbing core.
The content of the lignin component of the core cover sheet is 2-10%,
The absorbent article having a plurality of concave portions continuously extending from at least the surface sheet to a part of the liquid absorbing core in the thickness direction. The core cover sheet further has a second coating portion that covers the non-skin facing surface side of the liquid absorbing core, and the second coating portion and the back surface sheet are bonded to each other via an adhesive. The absorbent article according to claim 1. The concave portion has a bottom, and a part of the surface sheet, the core cover sheet, and the liquid-absorbing core is compressed, and the thin portion where the concave portion is located has the concave portion located. The absorbent article according to claim 1 or 2, which has a higher density than a thick portion that is not thickened. The absorbent article according to any one of claims 1-3, wherein the concave portion is an opening that penetrates the surface sheet and the absorber in the thickness direction. The absorbent article according to any one of claims 1-4, wherein the adhesive is a SIS-based hot melt adhesive. The absorbent article according to any one of claims 1-5, wherein the core cover sheet has a content of a lignin component higher than that of the peripheral region and has a plurality of high lignin regions scatteredly located in a plan view. The absorbent article according to any one of claims 1-6, wherein the core cover sheet has a crepe ratio of 7 to 20% and a formation index of 50 to 300. The surface sheet has a first portion and a second portion having a denser fiber density than the first portion, the first portion being joined to the high lignin region, and the second portion The absorbent article according to claim 6, which is joined to the peripheral area. The absorbent article according to any one of claims 1-8, wherein the surface sheet has a multi-layer structure, and the layer located on the skin-facing surface side is mainly composed of cotton fibers. The absorbent article according to claim 9, wherein the Krem water absorption of the surface sheet is lower than the Krem water absorption of the core cover sheet.

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