JP2019022699A - Absorbent article including nonwoven sheet for absorber and manufacturing method for nonwoven sheet used for absorbent article - Google Patents

Abstract

To provide an absorbent article including a nonwoven sheet for an absorber excellent in a liquid diffusion property that does not use intensity application means by post-coating and the like of an adhesive having a risk of inhibiting the liquid diffusion property, and a manufacturing method for the nonwoven sheet used in an absorbent article.SOLUTION: An absorbent article includes: a liquid permeable front surface sheet; a liquid impermeable rear surface sheet; an absorber which is located between the front surface sheet and the rear surface sheet; and a nonwoven sheet for the absorber. The nonwoven sheet includes: a pulp fiber layer including pulp and having a first surface and a second surface; a first surface side fiber layer which is arranged at a first surface side of the pulp fiber layer and mainly contains hydrophilic fiber having a mean fiber length of 25 mm-64 mm; and a second surface side fiber layer which is arranged at a second surface side of the pulp fiber layer and mainly contains the hydrophilic fiber having a mean fiber length of 25 mm-64 mm.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an absorbent article including a nonwoven fabric sheet for an absorbent body, and a method for producing a nonwoven fabric sheet used for the absorbent article.

  Absorbent articles such as disposable diapers, sanitary napkins, and panty liners are generally a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber disposed between the top sheet and the back sheet. In particular, the core wrap covering the superabsorbent polymer particles inside the absorbent body securely holds the superabsorbent polymer particles even when dry or wet. There is a demand for a function of quickly diffusing body fluids such as urine and blood reaching the absorbent article over a wide range of the absorbent body so that the body fluid is quickly absorbed by the superabsorbent polymer particles.

For example, in Patent Document 1, in a substantially longitudinal absorbent article having a liquid-permeable surface material, a liquid-retaining absorbent, and a liquid-impermeable leak-proof material, the absorbent is diffusible. And (a) the diffusible absorbent sheet has a hydrophilicity (cos θ) of 0.5 to 1 and has a longitudinal Clem water absorption. (B) The absorption retention sheet is a sheet composed of a fiber assembly having a capillary osmotic pressure of 4000 to 15000 [dyn / cm ² ], and is a physiological saline solution. A high-absorption polymer having an absorption rate of 40 to 70 [g / g] and an absorption rate of 2 [ml / 0.3 g polymer · min] or more is sandwiched by 10 to 100% by weight with respect to the fiber assembly. It consists of laminated sheets Osamusei article is disclosed (see claim 1 and the like).

JP-A-4-89053

  In the absorbent article disclosed in Patent Document 1, in order to maintain the strength of the diffusible absorbent sheet of the absorber, each fiber is bonded using polyvinyl alcohol or the like as a binder, or by a spunbond method. Since it is formed by fusing fibers together, the liquid diffusibility may be hindered by the bonded portion or the fused portion.

  Therefore, the present invention provides an absorbent article including a nonwoven fabric sheet for an absorbent body excellent in liquid diffusibility, which does not use strength imparting means by post-coating of an adhesive that may impede liquid diffusibility, and the like It aims at providing the manufacturing method of the nonwoven fabric sheet for absorbers used for an absorbent article.

  The absorbent article of the present invention comprises a liquid-permeable top sheet, a liquid-impermeable back sheet, an absorber positioned between the top sheet and the back sheet, and a nonwoven sheet for the absorber. An absorbent article comprising: a nonwoven fabric sheet comprising pulp, disposed on a pulp fiber layer having a first surface and a second surface, and a first surface side of the pulp fiber layer; and an average fiber length of 25 mm to A first surface side fiber layer mainly containing hydrophilic fibers of 64 mm, and a second surface side fiber mainly disposed of hydrophilic fibers having an average fiber length of 25 mm to 64 mm arranged on the second surface side of the pulp fiber layer. And a layer.

  According to the absorbent article of the present invention, the nonwoven fabric sheet for an absorbent body composed of three or more layers including a pulp fiber layer, a first surface side fiber layer, and a second surface side fiber layer inhibits liquid diffusibility. Since the fibers are entangled with each other by a high-pressure water flow without using a strength imparting means such as post-coating of an adhesive with a fear, a liquid such as a body fluid can be used as the first surface side fiber layer and the first layer. Utilizing the capillary phenomenon of the fiber aggregate forming the two-side fiber layer, it can be diffused widely and quickly in the surface direction of the nonwoven fabric sheet. Furthermore, since the 1st surface side fiber layer and the 2nd surface side fiber layer are arrange | positioned at the both surfaces side of the pulp fiber layer, it was spread | diffused in the surface direction in the 1st surface side fiber layer and the 2nd surface side fiber layer. The liquid can be absorbed from both surfaces of the pulp fiber layer, the water retention amount of the nonwoven fabric sheet can be remarkably improved, and liquid diffusion in the surface direction in the nonwoven fabric sheet can be realized continuously.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the absorbent article containing the nonwoven fabric sheet for absorbers excellent in liquid diffusibility, and the nonwoven fabric sheet for absorbers used for the said absorbent article can be provided.

FIG. 1 is a perspective view (schematic diagram) of a disposable diaper that is an embodiment of the absorbent article of the present invention. FIG. 2 is a plan view of the disposable diaper of FIG. 1 in a developed state. FIG. 3 is a cross-sectional view in the width direction along the line III-III ′ of FIG. 2. FIG. 4 is a cross-sectional view (schematic diagram) of a nonwoven fabric sheet according to an embodiment of the present invention.

  Hereinafter, preferred embodiments of the absorbent article of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view (schematic diagram) of a disposable diaper which is an embodiment of the absorbent article of the present invention, and FIG. 2 is a plan view of a state in which the disposable diaper of FIG. 1 is developed. As shown in FIG.1 and FIG.2, the disposable diaper 1 which is one Embodiment of this invention is the front part 11 applied to a wearer's abdomen, the intermediate part 12 applied to a wearer's crotch part, and a wearer. And a rear surface portion 13 applied to the back portion and / or the back portion. As shown in FIG. 1, in the joint portions 14 a and 14 b, the side portions 111 a and 111 b of the front surface portion 11 and the both side portions 131 a and 131 b of the rear surface portion 13 are joined to each other. A waist opening is formed by the end portion 132 of the surface portion 13, and leg openings are formed by both side portions 121 a and 121 b of the intermediate portion 12, and the disposable diaper 1 has a pants-type shape. .

  As shown in FIGS. 1 and 2, the disposable diaper 1 includes a top sheet 2 made of a liquid-permeable non-woven sheet, a plastic film, etc., a back sheet 3 made of a liquid-impermeable polyethylene film, and the like, and a top sheet 2. And an absorbent body 4 provided between the back sheet 3, a liquid-impermeable cover sheet 5, and elastic members 61, 62, 63, 64. The cover sheet 5 provided on the skin surface side surface of the top sheet 2 has an opening 51 formed at substantially the center, and a part of the top sheet 2 (a part of the arrangement region of the absorber 4) is It is exposed from the opening 51 of the cover sheet 5 and forms the skin surface side surface of the disposable diaper 1 together with the cover sheet 5.

  Further, as shown in FIGS. 1 and 2, elastic members 61, 62, 63, and 64 are provided between the back sheet 3 and the cover sheet 5 that are hourglass shapes having substantially the same dimensions. A waist gather is formed in the waist opening due to the elastic contraction force of the elastic members 61 and 62, and a leg gather (a cuff on the leg side) is formed in the leg opening due to the elastic contraction force of the elastic members 63 and 64. ) Is formed. Leakage of excrement from the leg opening can be prevented by this leg gather. In addition, in this specification, the width direction X refers to the width direction (short direction) in planar view in the disposable diaper 1 (absorbent article) in the unfolded state, and the longitudinal direction Y is the disposable in the unfolded state. In the diaper 1 (absorbent article), it refers to the longitudinal direction (front and rear direction of the wearer) in plan view, and the width direction X and the longitudinal direction Y are orthogonal to each other in plan view.

  Hereinafter, the absorber used for the disposable diaper (absorbent article) which concerns on one Embodiment of this invention and the nonwoven fabric sheet for this absorber are demonstrated in detail. FIG. 3 is a cross-sectional view in the width direction along the line III-III ′ in FIG. 2. As shown in FIG. 3, the absorbent body 4 in this embodiment includes an absorbent core 7 made of a water-absorbing material, an absorbent nonwoven fabric sheet 8 disposed on the back sheet 3 side of the absorbent core 7, and the absorbent body. A core wrap (not shown) that wraps the core 7 and the nonwoven fabric sheet 8. In the present invention, the nonwoven fabric sheet may be disposed in the core wrap sheet that wraps the absorbent core, or may be disposed outside the core wrap so as to contact the core wrap, but the nonwoven fabric sheet wraps the absorbent core. Since it is advantageous for absorbing and diffusing liquids such as body fluids, the nonwoven fabric sheet is preferably disposed in a core wrap sheet that wraps the absorbent core. In the present specification, “for absorber” means an absorber including an absorbent core and a core wrap that wraps the absorbent core, or is disposed so as to be in contact with the absorbent core, or is in contact with the core wrap outside the core wrap. Means something to arrange. In the present invention, in order to further improve the diffusibility of a liquid such as a body fluid that has passed through the surface sheet, a liquid diffusive sheet different from the nonwoven fabric sheet or the nonwoven fabric sheet is also provided on the surface sheet side of the absorbent core. You may arrange.

  Although the said absorption core is not restrict | limited in particular, For example, what carried out dispersion | distribution holding | maintenance of the superabsorbent polymer in fiber aggregates, such as a fluff pulp and a nonwoven fabric, can be used. The superabsorbent polymer has a three-dimensional network structure in which a water-soluble polymer is appropriately cross-linked, and can absorb 20 times or more of its own weight. Examples of such superabsorbent polymers include starch polymers, crosslinked carboxylmethylated cellulose, acrylic acid polymers such as polymers or copolymers of acrylic acid and alkali metal acrylates, and amino acid polymers. It is done.

  In this invention, the nonwoven fabric sheet for absorbers contains a pulp, is arrange | positioned at the 1st surface side of the pulp fiber layer which has a 1st surface and a 2nd surface, and the said pulp fiber layer, and average fiber length is 25 mm-64 mm The first surface side fiber layer mainly including the hydrophilic fiber and the second surface side fiber layer mainly disposed on the second surface side of the pulp fiber layer and having an average fiber length of 25 mm to 64 mm. Including three or more layers.

  In the present invention, “mainly containing hydrophilic fibers” means containing hydrophilic fibers in a proportion of more than 50% by mass with respect to the total mass. Therefore, in other words, it means that the hydrophilic fiber is contained in an amount of more than 50% by mass and less than 100% by mass and other components (for example, hydrophobic fiber etc.) of 0% by mass to less than 50% by mass.

  FIG. 4 is a cross-sectional view (schematic diagram) of a nonwoven fabric sheet according to an embodiment of the present invention. The nonwoven fabric sheet 8 in this embodiment includes a pulp fiber layer 81 having a first surface and a second surface, a first surface side fiber layer 82 disposed on the first surface side of the pulp fiber layer 81, and the pulp fibers. It is comprised by the laminated body of 3 layer structure containing the 2nd surface side fiber layer 83 arrange | positioned at the 2nd surface side of a layer.

  The pulp fiber layer in the present invention mainly contains pulp that is generally a cellulosic fiber having a fiber length of 1 to 10 mm (that is, it contains more than 50% by mass), preferably 100% by mass of pulp. It is configured. In addition, the type of pulp is not particularly limited, and any pulp such as wood pulp, non-wood pulp, and waste paper pulp can be used, but diffused in the first surface side fiber layer and the second surface side fiber layer. It is particularly preferable to use fluff pulp in that it has a high ability to absorb a liquid such as body fluid from the first surface side fiber layer and the second surface side fiber layer.

It is preferable that the said pulp contains a pulp with a Kajaani average fiber length of 2-3 mm from points, such as water absorption, water retention, a softness | flexibility, and ease of handling. “Kajaani average fiber length” is the value of JAPAN TAPPI paper pulp test method no. 52: 2000 refers to the length-weighted average fiber length measured by a Kajaani fiber length measuring instrument manufactured by Kajaani Automation. The basis weight of the pulp is not particularly limited, water retention, flexibility, from the viewpoint of bulkiness, preferably of about 5 to 60 g / m ^2, and more is of the order of 15 to 40 g / m ² preferable.

  The 1st surface side fiber layer and the 2nd surface side fiber layer in this invention mainly contain the hydrophilic fiber whose average fiber length is 25 mm-64 mm (namely, more than 50 mass% is included), Preferably it is 70 mass. % Or more. The hydrophilic fiber is not particularly limited, but from the viewpoint of liquid diffusibility, strength, flexibility, versatility, and the like, for example, cellulosic fibers, and more specifically, natural fibers such as cotton, Examples thereof include regenerated fibers such as rayon and cupra. Moreover, the rayon fiber which performed the hydrophilic process on the surface can also be used. Among these, rayon fibers can be particularly preferably used in terms of liquid diffusibility, strength after entanglement, ease of handling, versatility, and the like.

  In the present invention, the hydrophilic fiber preferably has an average fiber length in the range of 25 mm to 64 mm. When the average fiber length is within this range, the discharged body fluid or the like can be used for the nonwoven fabric sheet by utilizing the capillary phenomenon of the fiber assembly forming the first surface side fiber layer and the second surface side fiber layer. It can be diffused quickly and widely in the surface direction, and the diffused liquid can be easily delivered to the pulp fiber layer disposed between the first surface side fiber layer and the second surface side fiber layer. . In addition, “average fiber length” is measured on a glass plate with a scale of “A7.1.1 A method (standard method)” in “A7.1 Measurement of fiber length” in Annex A of JIS L 1015: 2010. The average fiber length measured in accordance with “Method of Measuring Fiber Length”. The above method is a test method corresponding to ISO 6989 issued in 1981.

  Further, the form of the hydrophilic fiber is not particularly limited, and may be one having a general circular cross section, or one having an irregular cross section such as a Y shape, a cross shape, or a hollow shape. These may be used in combination. If the hydrophilic fiber includes a fiber having an irregular cross section, the fiber having the irregular cross section has a large surface area and excellent liquid absorbency. Therefore, the liquid of the fiber assembly forming the first surface side fiber layer and the second surface side fiber layer is used. The diffusibility can be further improved.

  In the present invention, the first surface side fiber layer and the second surface side fiber layer have a component other than the hydrophilic fiber in a mass ratio that is less than the hydrophilic fiber (that is, a proportion of less than 50 mass%). ), Preferably 30% by mass or less. Examples of the other components include hydrophobic fibers, heat-fusible fibers, various treatment agents, fillers, and the like. Depending on the desired liquid diffusibility, strength, flexibility, water retention, production cost, etc. They can be used alone or in combination.

  As the hydrophobic fiber, for example, thermoplastic fibers such as polyethylene, polypropylene, nylon, polyester, or composite fibers combining these thermoplastic fibers can be used. However, strength, bulkiness, and flexibility when wet are used. In view of the above, it is preferable to use polyester fibers such as polyethylene terephthalate.

  In addition, the hydrophobic fiber is preferably a fiber that has been subjected to a hydrophilic treatment on the surface with a hydrophilic oil or the like from the viewpoint of liquid diffusibility, and more preferably a polyester fiber that has been subjected to a hydrophilic treatment. preferable. Although it does not restrict | limit especially as a hydrophilic oil agent used for a hydrophilic process, For example, an alkyl phosphate ester salt, an alkyl phosphate metal salt, etc. are mentioned. Furthermore, in the present invention, since the first surface side fiber layer, the pulp fiber layer, and the second surface side fiber layer are integrated by a high-pressure water flow such as a water jet as will be described later, it does not flow down by the high-pressure water flow. It is particularly preferable that the surface of the hydrophobic fiber is subjected to a hydrophilic treatment using a hydrophilic oil having durability (durable hydrophilic oil). Such durable hydrophilic oils are not particularly limited, but examples include polyether esters, ether nonions, polyether-modified silicones, sulfosuccinates, polyoxyethylene amide ethers, alkyl imidazoline type cations, polyglycerin polyesters, carbon numbers. Is a mixture of an alkyl phosphate ester salt of 10 to 30 with a betaine compound, sulfate ester salt or sulfonate salt having 10 to 30 carbon atoms, or a mixture of an alkyl phosphate ester salt and a polyether-modified silicone, etc. And a mixed oil.

  The heat-fusible fiber includes a thermoplastic resin having a low melting point such as polyethylene resin or low-melting polypropylene at least on its surface. For example, a single-component fiber of polyethylene resin; a single-component fiber of polypropylene resin A core-sheath type composite synthetic fiber having a core part made of polyethylene terephthalate resin and a sheath part made of polyethylene resin; a core-sheath type composite synthetic fiber having a core part made of polypropylene resin and a sheath part made of polyethylene resin; Is a core-sheath type composite synthetic fiber having a high melting point polypropylene resin and a sheath part having a low melting point polypropylene resin; a side-by-side type composite synthetic fiber comprising a polyethylene terephthalate resin and a polyethylene resin; a side-by-side type synthetic fiber comprising a polypropylene resin and a polyethylene resin Examples include composite synthetic fibers.

  When the first surface side fiber layer and the second surface side fiber layer contain heat-fusible fibers, the first surface side fiber layer, the pulp fiber layer, and the second surface side fiber layer are water jets as described later. After the non-woven sheet is integrated by high-pressure water flow, the low-melting resin of the heat-fusible fiber is melted and fused to other fibers by heat-treating the non-woven sheet, and the strength of the non-woven sheet In particular, the strength when wet can be improved. In addition, since the heat-fusible fiber is contained in a smaller proportion than the hydrophilic fiber by mass ratio, the liquid diffusibility of the nonwoven fabric sheet can be improved even if the fusion part is formed by the heat-fusible fiber. The strength of the nonwoven fabric sheet can be supplementarily reinforced without hindering.

  For the first surface side fiber layer and the second surface side fiber layer, a fiber web formed by a method such as an airlaid method can be used, but at least one of the first surface side fiber layer and the second surface side fiber layer is used. The fiber layer is preferably a card web formed using a card machine. By using the card web, even if the fiber length of the constituent fibers is long, the first surface side fiber layer, the pulp fiber layer and the second surface side fiber layer are integrated by a high-pressure water flow such as a water jet described later. In this case, the fibers in each fiber layer and the fibers in each fiber layer can be sufficiently entangled. The form of the card web is not particularly limited, and may be any form such as a parallel web, a cross web, and a random web.

  In addition, the 1st surface side fiber layer and 2nd surface side fiber layer in this invention are different structures, even if it is a fiber layer of the same structure (namely, the fiber layer, the compounding rate, and the structure of a layer are the same). Fiber layers (that is, fiber layers in which at least one of fiber types, blending ratios, and layer structures is different) may be used.

  Next, the manufacturing method of the nonwoven fabric sheet for absorbers used for the absorbent article of this invention is demonstrated. The non-woven fabric sheet includes a step of supplying at least a fiber web for a second surface side fiber layer containing hydrophilic fibers, and a step of supplying a pulp for a pulp fiber layer containing hydrophilic fibers on the fiber web; Supplying a fiber web for the first surface-side fiber layer containing hydrophilic fibers on the pulp, obtaining a laminate, and subjecting each fiber layer to high-pressure water flow treatment from both sides of the laminate. And a step of entanglement of the fibers. More specifically, the above-mentioned constituent fibers such as hydrophilic fibers are mixed as they are or in a predetermined blending ratio, and then processed by a card machine or the like to be used for a second web layer fiber layer such as a card web. Then, while conveying the produced fiber web, a pulp for a pulp fiber layer containing hydrophilic fibers such as fluff pulp is supplied onto the fiber web by air lay, etc. After supplying a fiber web for the first surface side fiber layer containing hydrophilic fibers such as a web to obtain a laminate, by applying high-pressure water flow treatment such as a water jet from both sides of the laminate, at least each The nonwoven fabric sheet which the said 1st surface side fiber layer, the said pulp fiber layer, and the said 2nd surface side fiber layer integrated can be obtained by making the fiber between fiber layers entangle. In addition, when the first surface side fiber layer and the second surface side fiber layer contain heat-fusible fibers, the nonwoven fabric sheet obtained as described above is further heat-treated to enhance the sheet strength. A non-woven sheet can be obtained.

  The nonwoven fabric sheet thus obtained has a structure in which the fibers in each fiber layer and the fibers in each fiber layer are entangled with each other by a high-pressure water flow such as a water jet, so that it has excellent sheet strength and liquid diffusibility. While it has, the delivery to the said pulp fiber layer of the liquid diffused in the surface direction of the nonwoven fabric sheet in the said 1st surface side fiber layer and the said 2nd surface side fiber layer can be accelerated | stimulated. Moreover, since the said 1st surface side fiber layer and the said 2nd surface side fiber layer after delivering a liquid to the said pulp fiber layer can absorb a liquid again and can be spread | diffused in a surface direction, in a nonwoven fabric sheet In this case, the cycle of absorption of liquid, diffusion in the surface direction, and delivery to the pulp fiber layer can be repeatedly executed, and the amount of liquid retained in the liquid diffusion region and the nonwoven fabric sheet by the continuous diffusion of liquid Can be significantly increased.

  Furthermore, the structure has a structure in which a part of the constituent fibers in at least one of the first surface side fiber layer and the second surface side fiber layer has penetrated into the pulp fiber layer by the high pressure water flow such as the water jet. In this case, the liquid diffused in the surface direction of the nonwoven fabric sheet in the first surface side fiber layer and the second surface side fiber layer can be easily transferred to the pulp fiber layer. The cycle of diffusion in the surface direction and delivery to the pulp fiber layer can be performed more rapidly, and as a result, the liquid diffusion rate and diffusion region (diffusion area) in the nonwoven fabric sheet can be further increased.

  In the present invention, the absorbent sheet has a liquid absorption height of 110 mm or more, more preferably 120 mm or more, still more preferably 130 mm or more, in a water absorption test by the Klemm method described later. It is. The nonwoven fabric sheet has a water absorption ratio in the water absorption test of preferably 2.0 times or more, more preferably 2.4 times or more, and still more preferably 3.0 times or more. When the liquid absorption height and the water absorption ratio are in these ranges, the liquid such as body fluid can be diffused quickly and widely in the surface direction of the nonwoven fabric sheet, and the liquid can be combined with the high liquid permeability. It can be quickly trapped inside the pulp fiber layer.

  In the present invention, the nonwoven fabric sheet preferably has a liquid absorption height of at least one of the first surface side fiber layer and the second surface side fiber layer higher than the liquid absorption height of the pulp fiber layer. . When the liquid absorption height in each fiber layer has such a relationship, in the above-described cycle, the first surface side fiber layer or the second surface side fiber layer has not yet absorbed the liquid in the pulp fiber layer, or water retention. Since it becomes easy to deliver a liquid to the area | region which is not carried out, the spreading | diffusion of a liquid can be implement | achieved more continuously and more rapidly, and the spreading | diffusion area | region of a liquid and a water retention amount in a nonwoven fabric sheet can be increased further.

  The water absorption test according to the Krem method can be measured in accordance with the water absorption test method according to JIS P 8141: 2004, and the specific procedure will be described in the examples described later.

In the present invention, the basis weight of the nonwoven fabric sheet preferably has a basis weight of 15 to 100 g / m ² from the viewpoint of liquid diffusibility, sheet strength, liquid permeability, and the like, and has a basis weight of 20 to 80 g / m ² . More preferably, it has a basis weight of 30 to 60 g / m ² . The basis weight of each fiber layer constituting the nonwoven fabric sheet is 10-60 g / m ^{2 for the} pulp fiber layer in terms of the entangled formation state between the fibers, liquid diffusibility, sheet strength, liquid permeability, and the like. It is preferable that the first side fiber layer and the second side fiber layer are within a range of about 5 to 50 g / m ² .

In addition, the density of the nonwoven fabric sheet is preferably 50 to 300 mg / cm ³ , more preferably 50 to 200 mg / cm ³ , considering the formation state of the capillaries necessary for liquid diffusion, sheet strength, and the like. More preferably, it is 60-150 mg / cm < ³ >.

  In this invention, the said nonwoven fabric sheet can be used as a member which can contact the absorber of an absorbent article, for example, the diffusion arrange | positioned in the said absorber in the surface sheet side and / or back surface sheet side of an absorption core. It can be used as an adhesive sheet or a core wrap that covers the absorbent core. When the nonwoven fabric sheet is used for such a member, liquids such as discharged body fluid are diffused in a wide range in the nonwoven fabric sheet, so that the liquid can be absorbed in a wide area of the absorbent core adjacent to the nonwoven fabric sheet. Furthermore, when the nonwoven fabric sheet is disposed on the back sheet side of the absorbent core, the amount of rewet in the absorbent article can be significantly reduced (for example, reduced by 20% or more).

  The present invention can be applied to various absorbent articles such as an incontinence pad, a sanitary napkin, and a panty liner, in addition to the disposable diaper of the above-described embodiment. In addition, the absorbent article of the present invention is not limited to the above-described embodiment and the following examples, and can be appropriately changed without departing from the object and spirit of the present invention.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is limited to this and is not interpreted.

Example 1
A rayon fiber (manufactured by Daiwabo Rayon Co., Ltd.) is prepared as a hydrophilic fiber, and a polyethylene terephthalate (PET) fiber (manufactured by Toyobo Co., Ltd.) having a hydrophilic surface treated with a durable hydrophilic oil is prepared as a hydrophobic fiber. After blending the PET fibers so that rayon fibers / PET fibers = 70% by mass / 30% by mass, a card web is prepared using a card machine so that the basis weight is 12.0 g / m ^2. This was used as the second surface side fiber layer. While transporting the produced card web, a fluff pulp for pulp fiber layer (NB416 made by Weyerhaeuser) was continuously put on the card web so that the basis weight was 21.0 g / m ^2. The pulp fiber layer was formed on the second surface side fiber layer. Next, a card web prepared in the same manner as the second surface side fiber layer is supplied onto the pulp fiber layer to form a first surface side fiber layer, and the first surface side fiber layer, the pulp fiber layer, and the first A laminate composed of a two-side fiber layer was obtained. While conveying the laminate thus obtained at a conveyance speed of 10 m / min, water jets (water pressure on the first surface side fiber layer side: 2 to 5 MPa, second surface side fiber layer side from the both surface sides of the laminate) The first surface side fiber layer is entangled between constituent fibers in each fiber layer and between each fiber layer by applying a high-pressure water flow treatment with a water pressure of 3 MPa, nozzle diameter: 92 μm, nozzle pitch: 0.5 mm, two rows) A nonwoven fabric sheet having a three-layer structure in which the pulp fiber layer and the second surface side fiber layer were integrated was obtained.

Example 2
A fluff pulp for the pulp fiber layer was produced in the same manner as in Example 1 except that the basis weight was supplied onto the card web so that the basis weight was 26.0 g / m ² to obtain a nonwoven fabric sheet having a three-layer structure. It was.

Example 3
Each card web forming the first surface side fiber layer and the second surface side fiber layer was manufactured in the same manner as in Example 2 except that it was produced without using hydrophobic fibers (PET fibers), and three layers were produced. A non-woven sheet having a structure was obtained.

Comparative Example 1
A rayon fiber (manufactured by Daiwabo Rayon Co., Ltd.) is prepared as a hydrophilic fiber, and a polyethylene terephthalate (PET) fiber (manufactured by Toyobo Co., Ltd.) whose surface is subjected to a hydrophilic treatment with a hydrophilic oil as a hydrophobic fiber is prepared. After blending PET fibers so that rayon fibers / PET fibers = 30% by mass / 70% by mass, a card web is prepared using a card machine so that the basis weight is 22.5 g / m ² , This was made into the fiber layer corresponding to the 2nd surface side fiber layer of this invention. While conveying the produced card web, a card web produced in the same manner as the fiber layer corresponding to the second surface side fiber layer is supplied onto the card web, and the card web is supplied to the first surface side fiber layer of the present invention. Corresponding fiber layers were formed to obtain a laminate composed of two fiber layers. While conveying the laminate obtained in this manner at a conveyance speed of 10 m / min, by applying a high-pressure water flow treatment using the same water jet as in Example 1 from both sides of the laminate, each fiber layer and each fiber layer The constituent fibers were entangled with each other to obtain a nonwoven fabric sheet having a two-layer structure in which the fiber layer corresponding to the first surface side fiber layer and the fiber layer corresponding to the second surface side fiber layer were integrated.

Comparative Example 2
The card web forming each fiber layer was manufactured in the same manner as in Comparative Example 1 except that it was prepared by blending so that rayon fiber / PET fiber = 50% by mass / 50% by mass. A nonwoven sheet was obtained.

Comparative Example 3
A card web forming each fiber layer was produced in the same manner as in Comparative Example 1 except that it was prepared by blending so that rayon fiber / PET fiber = 70% by mass / 30% by mass. A nonwoven sheet was obtained.

About each nonwoven fabric sheet of Examples 1 to 3 and Comparative Examples 1 to 3 obtained as described above, basis weight (g / m ² ), thickness (mm), density (g / cm ³ ), by the Krem method. The liquid absorption height (mm) after 5 minutes and the transport amount per unit mass (g / g) were measured by the measurement method described later. Moreover, the mixing ratio of the rayon fiber and the PET fiber in the first surface side fiber layer and the second surface side fiber layer is measured by a measuring method described later using each card web produced in the manufacturing process of the above-mentioned nonwoven fabric sheet. did. These measurement results are shown in Table 1.

  As shown in Table 1, the nonwoven fabric sheets of Examples 1 to 3 have a liquid absorption height of 120 mm or more and a transport amount of 3 g / g or more, which is extremely high compared to the nonwoven fabric sheets of Comparative Examples 1 to 3. The height and the transport amount were shown, and it was found that the liquid had excellent liquid diffusibility. Further, from the comparison of Examples 1 to 3, the higher the mixing ratio of the rayon fibers in the first surface side fiber layer and the second surface side fiber layer, the higher the liquid absorption height and the transport amount. It turned out that the liquid diffusibility of a nonwoven fabric sheet improves according to a ratio.

  The measurement method for each measurement item is as follows.

[Basis weight]
Ten samples having a size of 100 mm × 100 mm are collected, and the mass of each sample is measured. Next, the basis weight (g / m ² ) of each sample is calculated by dividing the mass (g) of each sample by the area (m ² ) of each sample. The average value of the basis weight of a total of 10 samples is calculated, and the average value is adopted as the basis weight.

[Thickness]
The thickness of the nonwoven fabric is measured using THICKNESS GAUGE UF-60 manufactured by Daiei Kagaku Seiki Seisakusho. In UF-60, the diameter of a measurement surface is 44 mm, the pressure of 0.3 kPa is applied to a nonwoven fabric, and the thickness is measured.

[density]
The density of the nonwoven fabric is calculated by dividing the basis weight of the nonwoven fabric by its thickness.

[Liquid absorption height and transport volume]
The liquid absorption height and transport amount after 5 minutes by the Krem method are measured in accordance with the water absorption test method according to JIS P 8141: 2004 as follows.
(1) The sample is cut into a size of 230 mm × 25 mm (length × width), a mark is drawn at a position 30 mm from the end in the length direction, and the initial mass (W ₀ ) of the test piece is measured. .
(2) The artificial urine is filled to a height of 35 mm in a rectangular parallelepiped immersion container of 170 mm × 90 mm × 40 mm (length × width × depth). The artificial urine is prepared by dissolving 200 g of urea, 80 g of sodium chloride, 8 g of magnesium sulfate, 3 g of calcium chloride, and about 1 g of pigment: Blue No. 1 in 10 L of ion-exchanged water.
(3) The test piece is fixed to a hanging tool so that the mark line is on the lower side, immersed in artificial urine up to the mark line, and left for 5 minutes.
(4) After standing for 5 minutes, the height of the artificial urine rising from the mark is measured as the liquid absorption height (mm).
(5) Next, the test piece is removed from the hanging tool, the 30 mm-long portion (the portion below the marked line) that has been immersed in the artificial urine is cut, and the mass (W ₁ ) of the remaining 200-mm portion. ).
(6) The transport amount (X) (g / g) is calculated according to the following formula.
X = {(W ₁ × 230/200) −W ₀ } / W ₀
(7) Repeat the above test 5 times and adopt the average value.

[Combination ratio of rayon fiber and PET fiber]
The blending ratio of rayon fibers and PET fibers in the card web is determined by measuring the blending ratio of rayon fibers according to the following procedure.
(1) A fiber web containing rayon fibers and PET fibers is prepared as a measurement sample.
(2) About 0.2 g of the fiber web is cut into a size enough to enter a 100 mL beaker, and the mass (g) of the cut fiber web (sample initial mass W _A ) is measured.
(3) The cut fiber web and 30 g of hexafluoroisopropanol are put into a 100 mL beaker and stirred at a rotation speed of 300 rpm for 1 hour.
(4) The contents of the beaker are filtered using filter paper whose mass (g) (filter paper initial mass W _F ) has been measured in advance.
(5) The residue on the filter paper is left in the draft chamber together with the filter paper, and dried there for 1 hour.
(6) Measure the mass (g) of the residue after drying and the filter paper.
(7) the sample initial weight W _A and the sum of the initial mass W _F of the filter paper, by dividing the mass of residue and the filter paper after the drying, the mass of the rayon fibers of the fiber in the web (g) (Rayon The fiber mass W _R ) is calculated.
(8) from the calculated rayon fiber mass and the sample initial weight W _A, according to the following equation to calculate the blend of rayon fibers ratio F _{A (wt%).}
F _A = (W _R / W _A ) × 100

  Below, the aspect of this invention assumed is illustrated.

  One aspect (aspect 1) of the present invention is a liquid-permeable top sheet, a liquid-impermeable back sheet, an absorber positioned between the top sheet and the back sheet, and a nonwoven sheet for the absorber And the non-woven fabric sheet includes pulp, a pulp fiber layer having a first surface and a second surface, and an average fiber length disposed on the first surface side of the pulp fiber layer. Is disposed on the second surface side of the pulp fiber layer, and mainly includes hydrophilic fibers having an average fiber length of 25 mm to 64 mm. It is the said absorbent article containing a surface side fiber layer.

  Moreover, in another aspect (aspect 2) of this invention, in the absorbent article of the aspect 1, at least one fiber layer of the first surface side fiber layer and the second surface side fiber layer is in a mass ratio. , Further comprising a smaller amount of hydrophobic fibers than hydrophilic fibers.

  Furthermore, in another aspect (Aspect 3) of the present invention, in the absorbent article according to Aspect 2, the hydrophobic fiber includes a thermoplastic fiber.

  Furthermore, in another aspect (Aspect 4) of the present invention, in the absorbent article according to Aspect 3, the thermoplastic fiber is a polyester fiber that has been subjected to a hydrophilic treatment.

  Furthermore, in another aspect (aspect 5) of the present invention, in the absorbent article according to any one of aspects 1 to 4, the hydrophilicity in at least one of the first surface side fiber layer and the second surface side fiber layer is determined. Fiber has a modified cross section.

  Furthermore, in another aspect (aspect 6) of the present invention, in the absorbent article according to any one of aspects 1 to 5, the hydrophilicity in at least one of the first surface side fiber layer and the second surface side fiber layer is determined. The functional fiber includes a cellulosic fiber.

  Furthermore, in another aspect (Aspect 7) of the present invention, in the absorbent article according to any one of Aspects 1 to 6, the pulp in the pulp fiber layer contains fluff pulp.

  Furthermore, in another aspect (Aspect 8) of the present invention, in the absorbent article according to any one of Aspects 1 to 7, the pulp in the pulp fiber layer contains a pulp having a Kajaani average fiber length of 2 to 3 mm.

  Furthermore, in another aspect (Aspect 9) of the present invention, the absorbent article according to any one of Aspects 1 to 8 includes a structure in which fibers between fiber layers are entangled by the action of water flow.

  Furthermore, in another aspect (aspect 10) of the present invention, in the absorbent article according to any one of aspects 1 to 9, at least one of the first surface side fiber layer and the second surface side fiber layer is a card. Including the web.

  Furthermore, in another aspect (aspect 11) of the present invention, in the absorbent article according to any one of aspects 1 to 10, fibers in at least one of the first surface side fiber layer and the second surface side fiber layer. Includes a structure in which a part of the inside penetrates into the pulp fiber layer.

  Furthermore, in another aspect (aspect 12) of the present invention, in the absorbent article according to any one of the aspects 1 to 11, the first surface side fiber layer and the second surface side fiber layer in a water absorption test by the Krem method. The liquid absorption height of at least one of the fiber layers is higher than the liquid absorption height of the pulp fiber layer.

  Furthermore, in another aspect (aspect 13) of the present invention, in the absorbent article according to any one of aspects 1 to 12, the absorbent body includes an absorbent core, and the nonwoven fabric sheet includes at least the back sheet and the absorbent core. Between.

  Furthermore, in another aspect (aspect 14) of the present invention, there is provided a method for producing a nonwoven fabric sheet for an absorbent body used in the absorbent article according to any one of aspects 1 to 13, wherein the second surface side includes hydrophilic fibers. A step of supplying a fiber web for a fiber layer, a step of supplying a pulp for a pulp fiber layer containing hydrophilic fibers on the fiber web, and a first surface side fiber containing hydrophilic fibers on the pulp Supplying the fiber web for the layer to obtain a laminate, and performing a high-pressure water flow treatment from both sides of the laminate to entangle the fibers at least between the fiber layers. It is.

DESCRIPTION OF SYMBOLS 1 Disposable diaper 2 Top sheet 3 Back sheet 4 Absorber 5 Cover sheet 61-64 Elastic member 7 Absorption core 8 Nonwoven fabric sheet

Claims (14)

An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back sheet, an absorbent body positioned between the top sheet and the back sheet, and a nonwoven sheet for the absorbent body. ,
The nonwoven fabric sheet is
A pulp fiber layer comprising pulp and having a first side and a second side;
A first surface side fiber layer that is disposed on the first surface side of the pulp fiber layer and mainly contains hydrophilic fibers having an average fiber length of 25 mm to 64 mm;
The said absorbent article including the 2nd surface side fiber layer which is arrange | positioned at the 2nd surface side of the said pulp fiber layer, and mainly contains the hydrophilic fiber whose average fiber length is 25 mm-64 mm.   2. The absorption according to claim 1, wherein at least one of the first surface side fiber layer and the second surface side fiber layer further includes a smaller amount of hydrophobic fibers than the hydrophilic fibers by mass ratio. Sex goods.   The absorbent article according to claim 2, wherein the hydrophobic fiber includes a thermoplastic fiber.   The absorptive article according to claim 3 in which said thermoplastic fiber is a polyester system fiber by which hydrophilic treatment was carried out.   The absorbent article as described in any one of Claims 1-4 in which the hydrophilic fiber in at least one fiber layer of the said 1st surface side fiber layer and the said 2nd surface side fiber layer has a deformed cross section.   The absorbent article as described in any one of Claims 1-5 in which the hydrophilic fiber in at least one fiber layer of the said 1st surface side fiber layer and the said 2nd surface side fiber layer contains a cellulosic fiber.   The absorbent article as described in any one of Claims 1-6 in which the pulp in the said pulp fiber layer contains a fluff pulp.   The absorbent article as described in any one of Claims 1-7 in which the pulp in the said pulp fiber layer contains a pulp with a Kajaani average fiber length of 2-3 mm.   The absorbent article as described in any one of Claims 1-8 containing the structure where the fiber of each fiber layer was entangled by the effect | action of a water flow.   The absorbent article as described in any one of Claims 1-9 in which at least one fiber layer of the said 1st surface side fiber layer and the said 2nd surface side fiber layer contains a card web.   11. The structure according to claim 1, comprising a structure in which a part of fibers in at least one of the first surface side fiber layer and the second surface side fiber layer enters the pulp fiber layer. Absorbent article according to item.   The water absorption height of at least one of the first surface side fiber layer and the second surface side fiber layer is higher than the liquid absorption height of the pulp fiber layer in a water absorption test by the Krem method. Absorbent article as described in any one of 1-11.   The absorptive article according to any one of claims 1 to 12 in which said absorber includes an absorptive core and said nonwoven fabric sheet is arranged at least between said back sheet and said absorptive core. It is a manufacturing method of the nonwoven fabric sheet for absorbers used for the absorptive article according to any one of claims 1 to 13,
Supplying a fiber web for the second surface side fiber layer containing hydrophilic fibers;
Supplying pulp for a pulp fiber layer containing hydrophilic fibers on the fiber web;
Supplying a fiber web for the first surface side fiber layer containing hydrophilic fibers on the pulp to obtain a laminate;
Applying the high-pressure water flow treatment from both sides of the laminate to entangle the fibers between at least the fiber layers.

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