JP7516194B2 - Absorbent articles - Google Patents

Description

The present invention relates to absorbent articles such as disposable diapers.

When absorbent articles such as disposable diapers, sanitary napkins, panty liners (discharge sheets), and incontinence pads are worn, skin rashes may occur due to sweating, etc. Therefore, in order to impart a skin care effect and suppress the occurrence of rashes, absorbent articles containing skin care agents have been proposed.
For example, Patent Literature 1 describes an absorbent article that includes an absorbent body and a top sheet having projections and recesses that contain a hydrophobic skin care agent and a hydrophilic skin care agent. In this absorbent article, the relationship between the mass ratios of the hydrophobic and hydrophilic skin care agents in the recesses and projections of the top sheet is specified to improve the transfer of the hydrophobic and hydrophilic skin care agents to the skin.

JP 2019-170534 A

In general, when a hydrophilic skin care agent is used in the top sheet of an absorbent article, the skin care agent dissolves in the wearer's excrement liquid absorbed by the top sheet, and the skin care agent tends to migrate to the absorbent body along with the excrement liquid, while the skin care ingredients tend not to migrate to the skin. In addition, when a hydrophobic skin care agent is used in the top sheet, excrement liquid tends not to be absorbed by the top sheet.

In the topsheet in which such a skin care agent is used, it is desired that the skin care effect be sustained while the absorbent article is in use.
The present invention relates to an absorbent article capable of sustaining skin care effects during use.

An absorbent article according to one aspect of the present invention includes a topsheet and an absorbent body.
The top sheet is placed on the wearer's skin side.
The absorbent body is disposed on the non-skin side of the topsheet.
The top sheet has a first sheet positioned on the wearer's skin side and a second sheet positioned on the wearer's non-skin side.
The top sheet has a plurality of recesses formed by portions where the first sheet and the second sheet are partially fixed, and a plurality of protrusions protruding toward the wearer's skin formed by portions where the first sheet is not fixed to the second sheet.
The second sheet contains a skin care agent of a hydrophobic component.
The second sheet is more hydrophobic than the first sheet.

As described above, the absorbent article of the present invention makes it possible to maintain the skin care effect during use.

FIG. 1 is a diagram showing an example of a disposable diaper as one embodiment of an absorbent article of the present invention, and is a schematic plan view of the skin side (top sheet side) showing the state in which the elastic members of each part are stretched and spread out flat. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. FIG. 2 is a schematic perspective view showing an enlarged view of a portion of the topsheet of the disposable diaper. FIG. 4 is a schematic partially enlarged cross-sectional view of the topsheet for explaining the configuration of the protrusions of the topsheet. FIG. 2 is a schematic partially enlarged cross-sectional view of the top sheet, illustrating the mechanism of the skin care effect.

Hereinafter, the absorbent article of the present invention will be described with reference to the drawings, taking a disposable diaper as an example of one embodiment.
<Overall composition of disposable diapers>
As shown in FIG. 1, the disposable diaper 1 of this embodiment is a so-called open-type disposable diaper. The disposable diaper 1 has a vertical direction X corresponding to the front-rear direction of the wearer, and a horizontal direction Y corresponding to the left-right direction of the wearer and perpendicular to the vertical direction X. Furthermore, the disposable diaper 1 has a thickness direction Z perpendicular to both the vertical direction X and the horizontal direction Y. In this specification, the skin side of each structure refers to the side that is located on the skin side of the wearer when the disposable diaper is worn. The non-skin side of each structure refers to the side that is located opposite to the skin side of the wearer when the disposable diaper is worn. In addition, with regard to the thickness direction Z, the side that is closer to the wearer's skin when worn may be referred to as the top, and the side that is closer to the clothing may be referred to as the bottom. Hereinafter, the disposable diaper 1 will be referred to as diaper 1.

The diaper 1 is divided into a ventral region A located on the ventral side in the longitudinal direction X, a dorsal region B located on the dorsal side in the longitudinal direction X, and a crotch region C located between the ventral region A and the dorsal region B.
The back region B includes side portions protruding outward in the lateral direction Y from the crotch region C. Fastening tapes 6 are provided on the side edges of the side portions in the lateral direction Y. Similarly, the abdominal region A includes side portions protruding outward in the lateral direction Y from the crotch region C. A landing tape (not shown) for adhering the fastening tape 6 is provided on the non-skin side surface of the abdominal region A. When worn, the back region B and the abdominal region A are adhered to each other by the fastening tape 6 and are positioned together around the hips and waist of the wearer.
The crotch region C is narrower than the ventral region A and the dorsal region B, with leg openings narrowed inward in the lateral direction Y, and is positioned around the wearer's crotch area, including the urination area and anus, when worn.
It should be noted that "when worn" here refers to a state in which the normally expected appropriate wearing position is maintained.

As shown in Figures 1 and 2, the diaper 1 has a top sheet 2, a back sheet 3, an absorbent body 4, side sheets 5, a pair of fastening tapes 6, an intermediate sheet 7, and a leak-proof sheet 8. The diaper 1 has a configuration in which the back sheet 3, the leak-proof sheet 8, the absorbent body 4, the intermediate sheet 7, and the top sheet 2 are laminated in the thickness direction Z. These components are joined together by known joining means such as a hot melt adhesive.

The absorbent body 4 extends along the longitudinal direction X, and is disposed between the top sheet 2 and the back sheet 3. That is, the absorbent body 4 is disposed on the non-skin side of the top sheet 2. The absorbent body 4 absorbs liquid excrement (hereinafter sometimes simply referred to as "liquid") such as urine of the wearer from the surface on the top sheet 2 side, and retains the liquid by diffusing it internally.
The absorbent body 4 has an absorbent core 40 and a core wrap sheet 41 .
The absorbent core 40 is mainly composed of an absorbent material capable of retaining liquid. Specifically, the absorbent core 40 has a structure in which a hydrophilic fiber stack is supported with an absorbent polymer, or a structure made of only a water-absorbent polymer, or the like.
The core wrap sheet 41 covers the absorbent core 40 and has a function of, for example, maintaining the shape of the absorbent core 40. The core wrap sheet 41 is formed of, for example, a thin, soft paper such as tissue paper or a liquid-permeable nonwoven fabric.

The top sheet 2 is placed on the skin side of the wearer. The top sheet 2 is placed on the skin side (upper in the thickness direction Z) of the absorbent body 4, and constitutes, for example, the central part in the lateral direction Y of the skin side of the diaper 1. The top sheet 2 is configured as a liquid-permeable sheet material, and is formed of a nonwoven fabric made of synthetic or natural fibers. Details of the top sheet 2 will be described later.

The intermediate sheet 7 is placed between the top sheet 2 and the absorbent body 4. The intermediate sheet 7 can be made of nonwoven fabric obtained by various manufacturing methods. The intermediate sheet 7 is placed from the viewpoint of improving the permeability of liquid from the top sheet 2 to the absorbent body 4 and preventing liquid absorbed by the absorbent body 4 from returning to the top sheet 2.

The back sheet 3 is disposed on the non-skin side (lower in the thickness direction Z) of the absorbent 4, and constitutes, for example, almost the entire non-skin side of the diaper 1, forming the exterior of the diaper 1 when worn. The back sheet 3 is preferably leak-proof, and is formed, for example, from a sheet material that has properties such as low liquid permeability, water vapor permeability, and water repellency.

The pair of side sheets 5 are disposed on the lateral sides of the top sheet 2 in the lateral direction Y, and, for example, constitute the lateral sides in the lateral direction Y of the skin side of the diaper 1. The side sheets 5 are desirably leak-proof, and are formed of a sheet material having, for example, properties such as poor liquid permeability, water vapor permeability, and water repellency. The pair of side sheets 5 are disposed such that the central sides in the lateral direction Y overlap the top sheet 2, and the lateral sides in the lateral direction Y extend to the outside of the top sheet 2 and are joined to the back sheet 3.
In the diaper 1, the side sheets 5 form a sheet for forming three-dimensional gathers. The side end portions of the side sheets 5 at the center in the lateral direction Y are free ends that are not joined to the top sheet 2 or the like, at least in the crotch region C, and are provided with elastic members 51. The elastic members 51 extend in the longitudinal direction X in the crotch region C, and may extend, for example, to parts of the abdominal region A and the dorsal region B. The provision of the elastic members 51 forms three-dimensional gathers.
Elastic members 52 that stretch in the vertical direction X, for example, are disposed near the side ends of the side sheets 5 on the outer side in the horizontal direction Y, thereby forming leg gathers that fit snugly around the legs of the wearer when worn.
The elastic members 51 and 52 are thread-like or band-like elastic members that are stretchable in the longitudinal direction X.

The pair of fastening tapes 6 have fastening parts 61 made of male members of a mechanical hook-and-loop fastener. A landing tape made of a female member of a mechanical hook-and-loop fastener is provided on the non-skin side of the abdominal region A of the diaper 1. The fastening parts 61 of the fastening tapes 6 can be removably attached to the landing tape.

The leak-proof sheet 8 is made of a liquid-impermeable or liquid-difficult-to-permeate resin film and covers the skin side of the back sheet 3.

<Surface sheet>
(Structure of surface sheet)
2 to 4, in the diaper 1 of this embodiment, the topsheet 2 is constructed by laminating a first sheet 21 located on the wearer's skin side and a second sheet 22 located on the wearer's non-skin side. The topsheet 2 has a skin side 2a and a non-skin side 2b. The skin side 2a is constructed by the first sheet 21 and has an uneven shape. The non-skin side 2b is constructed by the second sheet 22 and has a substantially flat shape.
The topsheet 2 has a plurality of protrusions 23 and a plurality of recesses 24 .
The recesses 24 are joints formed by partially embossing the first sheet 21 and the second sheet 22 and pressing them together, and then bonding and fixing them by thermal fusion. In each of the first sheet 21 and the second sheet 22, the recesses 24, which are the joints, are denser than the other portions. The recesses 24 are located between the protrusions 23.
The protrusions 23 are formed by portions of the first sheet 21 that are not fixed to the second sheet 22. The protrusions 23 protrude in a dome shape toward the wearer's skin. The inside of the protrusions 23 is hollow.
The convex portions 23 and concave portions 24 are arranged alternately in rows in one direction (vertical direction X in FIG. 3), and such rows are formed in multiple rows in a direction perpendicular to the one direction (horizontal direction Y in FIG. 3).
As shown in FIG. 4, the first sheet 21 has a skin side 21a and a non-skin side 21b opposite to the skin side 21a.

The first sheet 21 and the second sheet 22 are each made of a sheet-like material of a fibrous material. This sheet-like material is substantially non-stretchable. As the sheet-like material, various nonwoven fabrics such as nonwoven fabrics produced by a carding method, spunbond nonwoven fabrics, meltblown nonwoven fabrics, spunlace nonwoven fabrics and needlepunch nonwoven fabrics, and meltblown nonwoven fabrics, spunlace nonwoven fabrics and needlepunch nonwoven fabrics can be used.
Each of the first sheet 21 and the second sheet 22 is made of a nonwoven fabric of a plurality of fibers, and has heat-sealed parts 25 formed by heat-sealing the fibers to each other. In FIG.
As the raw material fibers for the first sheet 21 and the second sheet 22, core-sheath fibers, side-by-side fibers, etc. can be preferably used, with core-sheath fibers being particularly preferred. A representative fiber has a core component of PET (polyethylene terephthalate) and a sheath component of PE (polyethylene), and the core-sheath ratio is preferably 20/80 to 80/20 by mass. The fiber fineness is preferably 1.5 dtex or more and 5.0 dtex or less. The core-sheath ratio refers to the mass ratio (core/sheath) of the resins constituting the core and the sheath, respectively.

(First and second sheets)
The second sheet 22 contains at least a skin care agent containing a hydrophobic component (hereinafter, a skin care agent containing a hydrophobic component is referred to as a hydrophobic skin care agent.) More preferably, the second sheet 22 contains a hydrophilic skin care agent and a polyhydric alcohol having 2 to 4 carbon atoms in addition to the hydrophobic skin care agent.
The second sheet 22 is treated with a treatment agent that contains a hydrophobic skin care agent. In this embodiment, the treatment agent includes, in addition to a hydrophobic skin care agent, a hydrophilic skin care agent and a polyhydric alcohol. "Treated with a treatment agent" includes both a form in which fibers coated with a treatment agent are made into a nonwoven fabric, and a form in which fibers are made into a nonwoven fabric and then the treatment agent is applied to the nonwoven fabric.
A "skin care agent" is an agent that provides a skin care effect to the wearer. The "skin care effect" refers to the general efficacy of normalizing the condition of the skin, such as preventing skin rashes, reducing inflammation, preventing scratches, and providing antibacterial properties. Skin care agents and polyhydric alcohols will be described later.

The second sheet 22 is more hydrophobic than the first sheet 21. In other words, the first sheet 21 is more hydrophilic than the second sheet 22, and has higher liquid permeability.
The second sheet 22 is more hydrophobic than the first sheet 21 and contains a hydrophobic skin care agent, so that the top sheet 2 can have an improved durability of the skin care effect. The mechanism thereof will be described with reference to FIG. 5.

As shown in FIG. 5A, in the topsheet 2 at the initial stage of wear before urination, the second sheet 22 contains a hydrophobic skin care agent 11 .
Next, when excrement such as urine is supplied to the topsheet 2, as shown in Figure 5 (B), the second sheet 22, which has a higher hydrophobicity than the first sheet 21, causes the liquid 12 that passes through the first sheet 21 to be temporarily stored in the hollow convex portions 23 before transferring to the absorbent body 4. The skin care agents, including the hydrophobic skin care agent 11 contained in the second sheet 22, are then easily dispersed in the liquid 12 stored in the convex portions 23.
5(C), the liquid 12 in the convex portions 23 is absorbed into the absorbent body 4, and the hydrophobic skin care agent 11 dispersed in the liquid migrates to the first sheet 21. In this way, the hydrophobic skin care agent 11 present in the second sheet 22 at the beginning of wearing migrates to the first sheet 21, becoming more easily transferred to the wearer's skin, and a skin care effect is efficiently imparted to the wearer's skin.
In addition, when the wearer applies pressure while in a sitting position or other such position, the portion of the first sheet 21 forming the convex portion 23 comes into contact with the second sheet 22, and the hydrophobic skin care agent 11 contained in the second sheet 22 transfers to the first sheet 21.
In this way, while the diaper 1 is being worn, the hydrophobic skin care agent 11 contained in the second sheet 22 continues to migrate to the skin due to excretion and changes in posture of the wearer, thereby sustaining the skin care effect.

The degree of hydrophilicity or hydrophobicity of the first and second sheets 21 and 22 is indicated by a contact angle measured by a measuring method described later.
From the viewpoint of further achieving the above-mentioned effects, the contact angle of the first sheet 21 is 60° or more, preferably 65° or more, and 90° or less, preferably 85° or less, more specifically, it is preferable that it is 60° or more and 90° or less, and more preferably, it is 65° or more and 85° or less. The contact angle of the second sheet 22 is 75° or more, preferably 80° or more, and 130° or less, preferably 125° or less, more specifically, it is preferable that it is 75° or more and 130° or less, and more preferably, it is 80° or more and 125° or less.

In addition to the hydrophobic skin care agent, the second sheet 22 preferably contains a skin care agent with hydrophilic components (hereinafter, skin care agents with hydrophilic components are referred to as hydrophilic skin care agents) and a polyhydric alcohol. By using a hydrophobic skin care agent and a hydrophilic skin care agent, it is possible to achieve a balance between the ease of liquid spreading and the speed at which liquid drains off in the second sheet 22, resulting in a second sheet 22 with good liquid absorption and little liquid remaining on the sheet. This makes it easier for liquid to quickly transfer to the absorbent body 4.

The second sheet 22 is treated with a treatment liquid containing a hydrophilic skin care agent, a hydrophobic skin care agent, and a polyhydric alcohol. More specifically, the fibers constituting the second sheet 22 are coated with a hydrophilic oil agent (fiber treatment agent), and the second sheet 22 contains a hydrophilic oil agent, a hydrophilic skin care agent, a hydrophobic skin care agent, and a polyhydric alcohol. The hydrophilic oil agent is a fiber treatment agent that hydrophilizes the fiber surface. The hydrophilic oil agent is typically a hydrophilic surfactant.
The second sheet 22 may be produced by forming fibers coated with a treatment liquid containing a hydrophilic oil agent, a hydrophilic skin care agent, a hydrophobic skin care agent, and a polyhydric alcohol into a nonwoven fabric, or by applying a treatment liquid containing a hydrophilic skin care agent, a hydrophobic skin care agent, and a polyhydric alcohol to a nonwoven fabric formed from fibers coated with a hydrophilic oil agent.
The hydrophobic skin care agent and the polyhydric alcohol are preferably liquid or have high fluidity at 36°C. In particular, it is preferable that the hydrophilic skin care agent and the hydrophobic skin care agent have high fluidity in terms of migration to the skin. In this case, by using a hydrophilic oil agent that is solid or semi-solid at 36°C, a hydrophobic skin care agent that is liquid at 36°C or a hydrophilic skin care agent using a polyhydric alcohol as a solvent (for example, a plant extract described later) can be stably attached to the fibers, which is preferable in that it is possible to suppress the above-mentioned components from migrating excessively from the top sheet 2 to other members constituting the absorbent article in the scene of use. In particular, in the case of the above-mentioned liquid skin care agent or the mixture containing a liquid skin care agent, it is preferable in that if the migration of the skin care agent from the top sheet 2 to other members constituting the absorbent article in the scene of use is suppressed, the amount of the skin care agent migrating to the wearer's skin is easily maintained.

The first sheet 21 preferably contains a hydrophilic skin care agent, and since the first sheet 21 is located on the side of the top sheet 2 that contacts the wearer's skin, the hydrophilic skin care agent is easily transferred to the skin. This allows the skin care effect to be exerted from the initial stage of wearing the diaper 1. As described above, while the diaper 1 is being worn, the hydrophobic skin care agent 11 contained in the second sheet 22 continues to transfer to the skin due to excretion and changes in posture of the wearer, and since the first sheet 21 contains a hydrophilic skin care agent, the skin care effect can be maintained for a long period of time from the initial stage of wearing the diaper 1.
Furthermore, since the top sheet 2 contains both hydrophilic and hydrophobic skin care agents, the timing at which the skin care effect is exerted can be shifted according to the dry state before urination, changes in the degree of wetness due to urination or sweating, etc., and changes in the wearer's posture, etc., and the skin care effect can be efficiently maintained while the diaper 1 is being worn.

The preferred content per unit area of the skin care agent contained in the second sheet 22 is as follows.
The hydrophobic skin care agent is preferably present in an amount of from 1 x ^10-4% by mass to 0.5% by mass, relative to the fiber mass, from the viewpoint of obtaining the effects of the present invention, and in particular, from 2 x ^10-4 % by mass to 0.1% by mass, which is more preferred as it makes it easier to balance the effects of the present invention with the feel during use.
The amount of the hydrophilic skin care agent is preferably from 0.1% by mass to 150% by mass of the fiber from the viewpoints of improving the liquid permeability of the sheet and suppressing liquid residue, and from the viewpoint of a balance with the feeling of use, preferably from 0.2% by mass to 50% by mass.
The amount of polyhydric alcohol is preferably 3× ^10-4 % by mass or more and 1.0% by mass or less based on the fiber mass from the viewpoints of improving the liquid permeability of the sheet and suppressing liquid residue, and more preferably 8× ^10-4 % by mass or more and 0.5% by mass or less from the viewpoint of a balance with the feeling of use.

The preferred content per unit area of the hydrophilic skin care agent contained in the first sheet 21 is as follows.
The hydrophilic skin care agent is preferably present in an amount of 0.1% by mass or more and 150% by mass or less relative to the fiber mass from the viewpoint of a balance between good liquid permeability and the expression of skin care effects, and more preferably 0.2% by mass or more and 50% by mass or less from the viewpoint of a balance with usability.

The skin care agent and the polyhydric alcohol will be described below.
(Hydrophobic skin care agent)
The hydrophobic skin care agent is a skin care agent containing a hydrophobic component that is not water-soluble or water-dispersible or has extremely low solubility, and is a composition or compound that has efficacy such as protection, healing, etc. for the wearer's skin. More specifically, the hydrophobic component refers to a component that dissolves in an amount of less than 1 g when 10 g of the component is mixed in 1 L of ion-exchanged water and then left to stand for 24 hours, preferably a component that dissolves in an amount of 0.1 g or less, and particularly preferably a component that does not dissolve at all.
Examples of hydrophobic skin care agents include fatty acids having a carbon chain length of 12 to 28 or ester compounds of such fatty acids with glycerin, wax, petrolatum, etc., and it is particularly preferable that the agent contains an unsaturated fatty acid having a carbon chain length of 12 to 28 or a glycerin ester compound of such unsaturated fatty acid. The glycerin ester is a monoester, diester, or triester of glycerin and the above-mentioned unsaturated fatty acid, and it is particularly preferable that the glycerin ester is a triester. As an agent containing a fatty acid or a fatty acid compound, it is preferable to use natural product extracts such as argan oil and shea butter.
In particular, argan oil, a hydrophobic vegetable oil containing unsaturated fatty acids, maintains the balance of moisture and oil in the skin, preventing dryness and functioning as a skin care agent. Argan oil also contains a lot of unsaturated fatty acids such as oleic acid and linoleic acid, and has a strong ability to remove active oxygen, which can reduce skin damage caused by, for example, sunburn.

(hydrophilic skin care agent)
A hydrophilic skin care agent is a skin care agent containing a hydrophilic component that is water-soluble or water-dispersible, and is preferably capable of suppressing the occurrence of rash or inflammation, and, if rash or inflammation occurs, suppressing the progression of the rash or inflammation or alleviating the rash or inflammation. More specifically, a hydrophilic component refers to a component that has a dissolution or dispersion amount of 1 g or more when 10 g of the component is mixed in 1 L of ion-exchanged water and left to stand for 24 hours, preferably a dissolution or dispersion amount of 5 g or more, more preferably a dissolution amount of 1 g or more, even more preferably a dissolution amount of 5 g or more, and most preferably a dissolution amount of 1 g or more.
As the hydrophilic skin care agent, natural extracts such as peach leaf extract and witch hazel extract, polyethylene glycol, hydrophilic compounds having skin care functions, etc. can be used.
Among these, peach leaf extract (hydrophilic extract), which is a plant extract, is preferred because it has antibacterial and anti-inflammatory properties. The peach leaf extract, which is a hydrophilic component, dissolves in the liquid supplied to the top sheet 2 and transfers to the skin, thereby providing a skin care effect.
Furthermore, when a plant extract is included as a hydrophilic skin care agent, it is preferable to include peach leaf extract, witch hazel extract, bamboo leaf extract, etc., which have skin care effects. The plant extract, which is a hydrophilic component, dissolves or disperses in the liquid, such as urine, supplied to the top sheet 2, and transfers to the skin, thereby providing a skin care effect. In particular, peach leaf extract is preferable, since it has antibacterial and anti-inflammatory effects and functions as a hydrophilic skin care agent.

(Polyhydric alcohol)
As the polyhydric alcohol, an alcohol having 2 to 4 carbon atoms can be used. Typically, it is 1,3-butylene glycol. By using 1,3-butylene glycol, the moisturizing effect and lubricity are improved. By improving the lubricity, the friction between the skin and the nonwoven fabric can be reduced, and damage to the skin can be suppressed. 1,3-butylene glycol is a moisturizing liquid water-soluble base component, which has a smooth feel and is less sticky, keeps the skin moist, and functions as a hydrophilic skin care agent. In addition to being used as a moisturizing agent, 1,3-butylene glycol is also used as a solvent. For example, when peach leaf extract is used as a hydrophilic skin care agent, 1,3-butylene glycol can be used as a solvent for the peach leaf extract. 1,3-butylene glycol promotes the compatibility of each component. As a result, in a nonwoven fabric manufactured using a treatment agent containing a hydrophobic skin care agent, a hydrophilic skin care agent, and a polyhydric alcohol, such as the second sheet 22 of this embodiment, phase separation and peeling of the hydrophobic skin care agent such as argan oil is suppressed, so that the hydrophilic skin care agent, hydrophobic skin care agent, and polyhydric alcohol constituting the treatment agent can be uniformly and stably attached to the nonwoven fabric. Note that, although 1,3-butylene glycol is given as an example here, any polyhydric alcohol having 2 to 4 carbon atoms will have the same effect, and for example, propylene glycol may also be used. Propylene glycol can also be used as an extraction solvent for hydrophilic extracts.

The above-mentioned various skin care agents may be used alone or in combination. In the second sheet 22 of this embodiment, it is sufficient that at least a hydrophobic skin care agent is included. Furthermore, from the viewpoint of uniformly and stably attaching the hydrophobic skin care agent to the nonwoven fabric, improving the liquid permeability of the sheet, and suppressing residual liquid, it is more preferable that the second sheet 22 includes a hydrophilic skin care agent and a polyhydric alcohol in addition to the hydrophobic skin care agent.

It is preferable to use natural product extracts in skin care agents. For example, the skin of infants who wear the diaper 1 is thinner and has a poorer barrier function than that of adults, so the use of natural product extracts can suppress the occurrence of allergic reactions, etc. In addition, the use of natural product extracts makes it less likely that skin problems such as redness will occur on the skin inside the diaper.

(Method of manufacturing the top sheet)
An example of a method for producing the topsheet 2 will now be described .
The second sheet 22 is produced by coating fibers with a treatment agent consisting of a mixture containing a hydrophilic oil agent (fiber treatment agent), a hydrophilic skin care agent, a hydrophobic skin care agent, and a polyhydric alcohol, and then forming the fibers into a nonwoven fabric using an air-through method.
The fibers are coated with a treatment agent consisting of a mixture containing a hydrophilic oil agent (fiber treatment agent) and a hydrophilic skin care agent, and then made into a nonwoven fabric by an air-through process to produce the first sheet 21. The treatment agent may contain a polyhydric alcohol as a solvent for the hydrophilic skin care agent.
The multilayer top sheet having projections and recesses (top sheet 2 in this embodiment) can be manufactured according to conventional methods, but typically can be produced by overlapping and joining a first sheet having projections and recesses formed thereon and a flat second sheet in accordance with JP 2004-174234 A.

(Other surface sheet examples)
The first sheet 21 constituting the topsheet 2 may contain more hydrophilic skin care agent on the skin side 21a than on the non-skin side 21b. In this manner, the first sheet 21 may be configured so that the hydrophilic skin care agent is distributed in the thickness direction so that the hydrophilic skin care agent is more concentrated on the side closer to the wearer's skin.
Even with such a configuration, the hydrophilic skin care agent can be efficiently transferred to the skin when the diaper 1 is worn, and the skin care effect can be exhibited from the initial stage of wearing the diaper 1.
Such a first sheet 21, which contains more hydrophilic skin care agent on the skin side 21a than on the non-skin side 21b, can be produced by forming fibers coated with a hydrophilic oil agent (fiber treatment agent) into a nonwoven fabric, and then applying a liquid containing the hydrophilic skin care agent to the skin side of the nonwoven fabric by spray coating, coater coating, etc. Thereafter, for example, according to JP 2004-174234 A, the top sheet 2 can be produced by overlapping and bonding the uneven first sheet 21 and a flat second sheet 22 together.

As yet another example, the topsheet 2 may be configured so that on the uneven skin side 2 a of the topsheet 2 , the hydrophilic skin care agent is present in greater amounts in the protrusions 23 than in the recesses 24 .
When the diaper 1 is worn, the convex portions 23 are mainly in contact with the wearer's skin, and since the convex portions 23 have a relatively larger amount of hydrophilic skin care agent than the concave portions 24 on the skin side 2a, the hydrophilic skin care agent is efficiently transferred to the skin, and the skin care effect is exhibited from the beginning of wearing. Furthermore, the concave portions 24 have a higher fiber density than the convex portions 23, and are more likely to draw in liquid and have a higher liquid absorbency. Therefore, the hydrophilic skin care agent located in the concave portions 24 tends to dissolve in liquid and transfer to the absorbent body 4 together with the liquid. However, in this embodiment, the amount of hydrophilic skin care agent in the concave portions 24 on the skin side 2a is relatively smaller than that in the convex portions 23, and therefore transfer to the absorbent body 4 is suppressed. In this way, a topsheet 2 with good usage efficiency of the skin care agent can be obtained.
Such a topsheet 2 in which the hydrophilic skin care agent is present in greater amounts in the protrusions 23 than in the recesses 24 on the skin side 2a of the topsheet 2 having recesses and projections can be manufactured as follows.
A first sheet 21 is prepared by forming a nonwoven fabric from fibers coated with a hydrophilic oil agent (fiber treatment agent). Next, for example, according to JP 2004-174234 A, the first sheet 21 with the unevenness formed thereon and a flat second sheet 22 are overlapped and joined to produce a laminated sheet. Next, a liquid containing a hydrophilic skin care agent is applied to the uneven skin side 2a of the laminated sheet by spray coating, coater coating, or the like, to produce the top sheet 2.
By spraying or coating the uneven skin side 2a with a liquid containing a hydrophilic skin care agent in this manner, the mixed liquid is concentrated in the convex portions 23 rather than in the concave portions 24. As a result, the surface sheet 2 has a skin side 2a with unevenness in which more of the hydrophilic skin care agent is present in the convex portions 23 than in the concave portions 24. Furthermore, the first sheet 21 of the surface sheet 2 produced in this manner contains more hydrophilic skin care agent on the skin side 21a than on the non-skin side 21b.

<Additional explanation>
[Method for confirming that the first and second sheets contain a skin care agent or the like]
The first sheet and the second sheet are separated from the top sheet, and a sample of a predetermined size (for example, 50 mm in the vertical direction × 50 mm in the horizontal direction) is cut out from the separated first sheet or second sheet.
The sample is placed in a container with a small opening at the bottom. Then, the fiber is held down with a lid, the fiber is pushed to the bottom of the container, and the lid is removed. 10 cc of ether or 10 cc of a mixed solution of ethanol/methanol (volume ratio 1:1) is poured therein and left to stand for 10 minutes. Ether is a solvent mainly intended for the extraction of hydrophobic skin care agents, and the mixed solvent of ethanol/methanol is a solvent intended for the extraction of hydrophilic skin care agents and polyhydric alcohols. Then, the lid is placed again and the fiber containing the solution is pressed hard to squeeze out the liquid (ether or ethanol/methanol component) contained in the fiber, and the squeezed liquid is poured into a weighing dish. Then, the weighing dish is heated to remove the solvent, and the weight of this weighing dish is measured, and the amount of the skin care agent is measured from the difference with the weight of the original weighing dish before the liquid was poured. Since the skin care agent can be measured in this way, it can be confirmed that the first sheet or the second sheet contains a hydrophobic skin care agent, a hydrophilic skin care agent, and a polyhydric alcohol.
The content of the skin care agent per unit area in the first or second sheet can be measured as follows. The amount of the skin care agent in three samples is measured as described above, and the average is taken as the skin care agent content. The amount of the skin care agent per unit area can then be calculated from the area of the sample and the skin care agent content. In a sample of the above size, the area is 2500 mm2 for the substantially flat second sheet. In calculating the area of the first sheet having a plurality of convex portions, the cross section is observed under magnification (e.g., 150 to ⁵⁰⁰ times magnification) using a scanning electron microscope (e.g., JCM-5100 (product name) manufactured by JEOL Ltd.), and the dimensions of the concaves and convexes are measured from the cross-sectional image, and the area of the concave-convex surface of the first sheet is calculated based on this.
In addition, hydrophobic skin care agents may be extracted into the ethanol/methanol extraction solvent. When the hydrophilic skin care agent, hydrophobic skin care agent, and polyhydric alcohol are all extracted with ethanol/methanol, this means that each component has polarity, which is advantageous in terms of affinity with the wearer's skin surface, and is therefore preferable.

Furthermore, the presence of a greater amount of hydrophilic skin care agent on the skin side of the first sheet than on the non-skin side can be confirmed by the following method.
The first sheet and the second sheet are separated from the top sheet. A predetermined amount (e.g., 2 g) of the fibers located on the outermost layers of each of the skin side and non-skin side of the separated first sheet is collected, and the skin care agent is extracted with an ethanol/methanol mixed solution in the same manner as described above, and the amount of the skin care agent is measured. The measurement results allow confirmation of the difference in the amount of hydrophilic skin care agent present on each of the skin side and non-skin side of the first sheet.

Furthermore, the presence of more hydrophilic skin care agent in the convex areas than in the concave areas on the skin side of the topsheet can be confirmed by the following method.
A predetermined amount (e.g., 2 g) of fibers located on the outermost layer of each of the convex and concave portions on the skin side of the topsheet is collected, and the skin care agent is extracted with an ethanol/methanol mixed solution in the same manner as described above, and the amount of the skin care agent is measured. From the measurement results, it is possible to confirm the difference in the amount of hydrophilic skin care agent present in each of the convex and concave portions.

[Contact angle measurement method]
The contact angle can be measured as follows.
A medium-magnification zoom lens (with illumination ring) was used on a Keyence microscope VH-8000 in a state where it was inclined at 90°, and the measurement was performed under conditions of 500x magnification. The measurement sample was a surface sheet cut to a size of 150 mm in the vertical direction x 70 mm in the horizontal direction. The measurement environment was 20°C/50% RH, and the measurement sample was set on the measurement stage with the measurement surface facing up so that it could be observed from the CD direction of the web (nonwoven fabric). Next, 2 μl of ion-exchanged water (hereinafter simply referred to as "water") was attached to the set measurement sample with a micropipette, and an image was captured within 5 seconds of attachment (preferably 2 to 3 seconds). The reason why it is necessary to capture the image shortly after attachment is that the attached water droplets are evaporated by the light emitted from the measurement unit of the microscope and to prevent the contact angle from changing due to the oil agent. The contact angle was measured at 10 observation points where both ends or one end of the water drop were clearly in focus, and the average of these was taken as the "contact angle." The contact angle was measured by drawing a tangent to the water drop fiber on an image or printed photograph, and using image analysis or a protractor.

The contact angle with water is an index showing the degree of hydrophilicity/hydrophobicity of the components such as the first and second sheets. The larger the contact angle, the more hydrophobic the component is determined to be. Therefore, the contact angle can be used to confirm that the second sheet is more hydrophobic than the first sheet. In general, the contact angle θ of components classified as hydrophilic is 90° or less (preferably 85° or less; the smaller the angle, the higher the hydrophilicity), and the contact angle θ of components classified as hydrophobic is greater than 90° (preferably greater than 90° to 140°).

In measuring the contact angle of the first sheet in a top sheet of a laminated structure having a first sheet and a second sheet, the first sheet and the second sheet are separated, and then the measurement is performed using the skin side and non-skin side of the first sheet as the measurement surfaces, respectively. The contact angles of the skin side and non-skin side of the first sheet indicate the degree of hydrophilicity/hydrophobicity of the first sheet.
On the other hand, the contact angle of the second sheet is measured by using the skin side of the second sheet as the measurement surface. The measurement result is the contact angle of the second sheet. The measurement result indicates the degree of hydrophilicity/hydrophobicity of the second sheet.
The second sheet being more hydrophobic than the first sheet means that the contact angle of the skin side of the second sheet is greater than the contact angle of each of the skin side and non-skin side of the first sheet.

<Other configuration examples>
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, a disposable diaper is shown as an example of an absorbent article, but the absorbent article is not limited thereto. The absorbent article of the present invention may be a urine pad, a panty liner, a sanitary napkin, etc. Absorbent articles are generally configured to have a liquid-permeable top sheet, a liquid-impermeable back sheet, and a liquid-retentive absorbent interposed between the two sheets.

1... Disposable diapers (absorbent articles)
Reference Signs List 2: Top sheet 4: Absorbent body 11: Hydrophobic skin care agent 21: First sheet 22: Second sheet 23: Convex portion 24: Concave portion

Claims (7)

An absorbent article comprising a top sheet arranged on the skin side of a wearer and an absorbent body arranged on the non-skin side of the top sheet,
The top sheet has a first sheet positioned on the skin side of the wearer and a second sheet positioned on the non-skin side of the wearer,
the top sheet has a plurality of recesses formed by portions where the first sheet and the second sheet are partially fixed, and a plurality of protrusions formed by portions where the first sheet is not fixed to the second sheet, the protrusions protruding toward the skin side of a wearer,
The first sheet does not contain a skin care agent having a hydrophobic component,
the second sheet contains a skin care agent having a hydrophobic component;
The second sheet is more hydrophobic than the first sheet. 2. The absorbent article of claim 1, wherein the second sheet is treated with a treatment agent that includes the hydrophobic skin care agent, the hydrophilic skin care agent, and a polyhydric alcohol. The absorbent article of claim 2 , wherein the hydrophobic component skin care agent comprises an unsaturated fatty acid or an unsaturated fatty acid compound. The absorbent article according to claim 2 or 3, wherein the polyhydric alcohol has 2 to 4 carbon atoms. The absorbent article according to claim 2 , wherein the first sheet comprises a skin care agent having a hydrophilic component. The absorbent article of claim 5 , wherein the first sheet has a greater amount of the hydrophilic skin care agent on the skin side than on the non-skin side. The absorbent article according to claim 5 or 6, wherein the skin care agent having a hydrophilic component is present in a greater amount in the protrusions than in the recesses on the skin side of the topsheet.

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