Absorbent article surface material

Abstract

To provide a surface material of an absorbent article which can exhibit efficient antibacterial effects.SOLUTION: A surface material of an absorbent article comprises: multiple fusion parts which are formed by heat seal of intersections of constitution fibers. The constitution fibers have on surfaces, a metal oxide antibacterial agent. In one constitution fiber, the constitution fiber has a linear part between two fusion parts, and the linear part includes a first portion extending from the fusion part. The fusion part includes a larger blending amount of the metal oxide antibacterial agent per a unit surface area, than that in the first portion.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a surface material for absorbent articles such as disposable diapers. [Background technology]

[0002] 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 prevent the occurrence of rashes, absorbent articles that use antibacterial agents have been proposed. For example, Patent Documents 1 and 2 describe absorbent articles in which an antibacterial agent is kneaded into the fibers constituting the surface material that comes into contact with the wearer's skin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-55187 A [Patent Document 2] Patent Publication No. 2021-52938 Summary of the Invention [Problem to be solved by the invention]

[0004] In absorbent articles that use antibacterial agents, there has been an issue that the antibacterial agent is poorly soluble in water, meaning that excretory liquids such as urine penetrate the surface sheet (surface material) before the antibacterial effect can be fully exerted, making it difficult to efficiently exert the antibacterial effect.

[0005] The present invention relates to a surface material for an absorbent article that is capable of exhibiting an efficient antibacterial effect. [Means for solving the problem]

[0006] The surface material of the absorbent article according to one embodiment of the present invention has a plurality of fused portions formed by thermally fusing intersections of constituent fibers. The constituent fibers have a metal oxide antibacterial agent on the surface. When focusing on one of the constituent fibers, the constituent fiber has a linear portion between the two fused portions, and the linear portion includes a first portion extending from the fused portion. The fused portion has a greater amount of the metal oxide antibacterial agent per unit surface area than the first portion.

[0007] An absorbent article according to one aspect of the present invention includes an absorbent body and a surface material of the absorbent article that is located on the skin side of the absorbent body. Effect of the Invention

[0008] The surface material of the absorbent article of the present invention can exhibit an efficient antibacterial effect. [Brief description of the drawings]

[0009] [Figure 1] 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 (surface material side) showing the state in which the elastic members of each part have been stretched and spread out flat. [Diagram 2] 2 is a schematic cross-sectional view of the absorbent article taken along line II-II in FIG. 1. [Diagram 3] 3(A) is a schematic enlarged view of the constituent fibers of a first example of a nonwoven fabric constituting a surface material that is part of the above-mentioned disposable diaper, (B) is a schematic cross-sectional view of the fused portion of the constituent fibers cut along line IIIB-IIIB in FIG. 3(A), and (C) is a schematic cross-sectional view of a first portion of the constituent fibers cut along line IIIC-IIIC in FIG. 3(A). [Figure 4] 4(A) is a schematic enlarged view of the constituent fibers of a second example of a nonwoven fabric constituting a surface material that is part of the above-mentioned disposable diaper, (B) is a schematic cross-sectional view of the fused portion of the constituent fibers cut along line IVB-IVB in FIG. 4(A), (C) is a schematic cross-sectional view of a first portion of the constituent fibers cut along line IVC-IVC in FIG. 4(A), and (D) is a schematic cross-sectional view of a second portion of the constituent fibers cut along line IVD-IVD in FIG. 4(A). [Diagram 5]FIG. 2 is a schematic cross-sectional view of an example of a surface material containing the above-mentioned constituent fibers, the surface material having a flat structure. [Figure 6] FIG. 2 is a perspective view of an example of a surface material containing the above-mentioned constituent fibers, the surface material having a skin side with an uneven structure. [Figure 7] FIG. 2 is a schematic cross-sectional view of an example of a surface material containing the above-mentioned constituent fibers, which is a two-layer structure and has a skin-side surface with an uneven structure. [Figure 8] FIG. 2 is a schematic diagram of a stretching device for explaining a production example of a nonwoven fabric containing the above-mentioned constituent fibers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Overall composition of disposable diapers> Hereinafter, an absorbent article provided with the surface material of the present invention will be described with reference to the drawings, taking a disposable diaper as an example.

[0011] The disposable diaper 1 of this embodiment shown in Fig. 1 is a so-called flat-type disposable diaper. However, the surface material of the present invention is not limited to flat-type disposable diapers, and can also be applied to pants-type disposable diapers. The disposable diaper 1 and each of the components constituting the disposable diaper 1 have a longitudinal direction X corresponding to the front-to-back direction of a wearer, and a transverse direction Y corresponding to the left-to-right direction of the wearer and perpendicular to the longitudinal direction X. Furthermore, the disposable diaper 1 and each of the components constituting the disposable diaper 1 have a thickness direction Z perpendicular to both the longitudinal direction X and the transverse direction Y. In this specification, the "skin side" of each component refers to the side that is closest to the wearer's skin when the disposable diaper is worn. The "non-skin side" of each component refers to the side that is opposite to the skin side of the wearer when the disposable diaper is worn. In addition, with respect to the thickness direction Z, the side that is closest to the wearer's skin when worn may be referred to as the "upper" side, and the side that is closest to the clothing may be referred to as the "lower" side. The disposable diaper 1 will be referred to as diaper 1 hereinafter.

[0012] As shown in FIG. 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 9 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) is provided on the non-skin side of the abdominal region A for adhering the fastening tape 9. The landing tape is made of a female member of a mechanical hook-and-loop fastener. The fastening tape 9 has a fastening portion 91 made of a male member of a mechanical hook-and-loop fastener. The crotch region C has leg openings that are narrower inward in the lateral direction Y than the ventral region A and the dorsal region B, 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.

[0013] 1 and 2, the diaper 1 comprises a surface material (top sheet) 2, a back material (back sheet) 3, an absorbent body 4, side sheets 5, a pair of fastening tapes 9, an intermediate sheet 7, and a leak-proof sheet 8. The diaper 1 has a configuration in which the back material 3, the leak-proof sheet 8, the absorbent body 4, the intermediate sheet 7, and the surface material 2 are laminated in the thickness direction Z. These components are joined together by known joining means such as a hot melt adhesive.

[0014] The absorbent body 4 extends along the longitudinal direction X, and is disposed between the front material 2 and the back material 3. That is, the absorbent body 4 is disposed on the non-skin side of the front material 2. The absorbent body 4 absorbs liquid excretions (hereinafter sometimes simply referred to as "liquid" or "excreted liquid") such as moisture contained in the wearer's urine and feces from the surface on the front material 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.

[0015] The surface material 2 is disposed so as to come into contact with the wearer's skin when the diaper 1 is worn. The surface material 2 is disposed on the skin side 4a side (upper side in the thickness direction Z) of the absorbent body 4, and constitutes, for example, the center in the lateral direction Y of the skin side of the diaper 1. The surface material 2 is configured as a liquid-permeable sheet material, and is formed of a nonwoven fabric made of synthetic or natural fibers, or the like. The surface material 2 has a skin side 2a and a non-skin side 2b.

[0016] An intermediate sheet 7 may be provided between the surface material 2 and the absorbent body 4. Nonwoven fabrics obtained by various manufacturing methods can be used for the intermediate sheet 7. The intermediate sheet 7 is arranged from the viewpoints of improving the permeability of liquid from the surface material 2 to the absorbent body 4, preventing liquid absorbed in the absorbent body 4 from returning to the surface material 2, etc.

[0017] The back surface material 3 is disposed on the non-skin side (lower in the thickness direction Z) of the absorbent body 4 and, for example, constitutes almost the entire non-skin side of the diaper 1 and constitutes the exterior of the diaper 1 when worn. The back surface material 3 is preferably leak-proof, and is formed, for example, from a sheet material having properties such as low liquid permeability, water vapor permeability, and water repellency.

[0018] The pair of side sheets 5 are disposed on the lateral sides in the lateral direction Y of the surface material 2, and constitute, for example, 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, for example, from a sheet material having 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 surface material 2, and the lateral sides in the lateral direction Y extend to the outside of the surface material 2 and are joined to the back surface material 3. In the diaper 1, the side sheets 5 have thread-like or strip-like elastic members 50 arranged thereon, thereby forming standing gather forming sheets.

[0019] The leak-proof sheet 8 is made of a liquid-impermeable or liquid-slightly permeable resin film, and covers the skin-facing side of the backing material 3 .

[0020] <Component fibers that make up the surface material> The surface material 2 is a nonwoven fabric composed of a plurality of constituent fibers. Concerning the constituent fibers of the surface material 2, constituent fibers 60A of a first example will be described with reference to Fig. 3, and constituent fibers 60B of a second example will be described with reference to Fig. 4. Each of the constituent fibers 60A and 60B is a fiber containing a metal oxide antibacterial agent in which the metal oxide antibacterial agent 6 is unevenly distributed so that a relatively large amount of the metal oxide antibacterial agent 6 is located in the fused portion 63 formed by heat fusion with the other constituent fiber when focusing on one constituent fiber. Hereinafter, the constituent fiber 60A will be referred to as the fiber containing a metal oxide antibacterial agent 60A, and the constituent fiber 60B will be referred to as the fiber containing a metal oxide antibacterial agent 60B. When there is no need to particularly distinguish between 60A and 60B, they will be referred to as the fiber containing a metal oxide antibacterial agent 60. The metal oxide antibacterial agent 6 will be described later.

[0021] Here, absorbent articles such as diapers are designed to prevent leakage, and therefore the inside of the diaper is a hot and humid environment due to moisture from sweat, urine, etc. As such, the inside of the diaper is an environment in which the skin becomes steamy and macerated, which tends to weaken the skin's barrier function, and also in which bacteria can easily grow inside the diaper after urination or defecation. Feces also contain enzymes such as proteolytic enzymes and lipolytic enzymes, as well as intestinal bacteria such as Escherichia coli and Staphylococcus aureus. Staphylococcus aureus is a bad bacterium that has a negative effect on the skin. When urination occurs, the urea contained in the urine is broken down by Staphylococcus aureus and converted into ammonia, creating an alkaline environment inside the diaper. When the diaper becomes an alkaline environment, the activity of Staphylococcus aureus becomes active, and Staphylococcus aureus produces toxins that cause skin problems such as inflammation, eczema, and skin rashes. In addition, if there is feces in the diaper, the alkaline environment inside the diaper activates the enzymes in the feces, irritating the skin, which has been macerated and has a weakened barrier function, and is prone to causing skin problems.

[0022] In contrast, in the present invention, the surface material 2 that comes into contact with the wearer's skin uses metal oxide antibacterial agent-containing fiber 60 that contains a metal oxide antibacterial agent 6, so that the antibacterial effect can be achieved from the early stage of excretion. Moreover, in the present invention, the metal oxide antibacterial agent-containing fibers 60 used in the surface material 2 are configured to be distributed so that a relatively large amount of the metal oxide antibacterial agent 6 is located in the fused parts 63. This makes it possible to obtain a more efficient and effective antibacterial effect, inhibit the proliferation of bacteria caused by the wearer's excrement from the early stages of excretion, and maintain a good balance of normal bacteria on the skin, resulting in an absorbent article that is less likely to cause skin troubles. A more detailed explanation will be given below by giving a first example and a second example.

[0023] [Example 1] As shown in FIG. 3(A), the first example of the fiber 60A containing the metal oxide antibacterial agent contains the metal oxide antibacterial agent 6, and more specifically, as shown in FIG. 3(B) and (C), the fiber is formed by kneading the metal oxide antibacterial agent 6 into the fiber. The fiber 60A containing the metal oxide antibacterial agent has a plurality of fused parts 63 formed by heat-sealing the intersections of the fibers 60A containing the metal oxide antibacterial agent. When focusing on one fiber 60A containing the metal oxide antibacterial agent, the fiber 60A containing the metal oxide antibacterial agent has a plurality of fused parts 63 heat-sealed at the intersections with other fibers 60A containing the metal oxide antibacterial agent, and a linear part 65 located between two adjacent fused parts 63. In the example shown in FIG. 3(A), the linear part 65 is formed from the first part 61.

[0024] As shown in FIG. 3(A), in fiber 60A containing a metal oxide antibacterial agent, the amount of metal oxide antibacterial agent 6 contained per unit area is greater in fused portions 63 than in first portions 61. In this specification, the "amount of metal oxide antibacterial agent per unit surface area" refers to the amount of metal oxide antibacterial agent located on the fiber surface per unit surface area.

[0025] The inter-fiber distance between the linear portions 65 is wider than the inter-fiber distance near the fused portions 63. Therefore, in the surface material 2 of the absorbent article formed using the metal oxide antibacterial agent-containing fiber 60A, when excrement such as urine or feces is supplied, the excrement is more likely to accumulate in the fused portions 63. As described above, in the fiber 60A containing the metal oxide antibacterial agent, the amount of the metal oxide antibacterial agent 6 is greater in the fused portions 63 than in the first portions 61, so that the metal oxide antibacterial agent 6 can be brought into contact with excrement efficiently and frequently, enabling efficient antibacterial action. On the other hand, the amount of the metal oxide antibacterial agent 6 is relatively smaller in the linear portions 65, where excrement is less likely to accumulate than in the fused portions 63, so that the overall amount of the metal oxide antibacterial agent 6 in the surface material 2 can be reduced, and the balance of normal bacteria on the skin can be well maintained.

[0026] Thus, the surface material 2 using the fiber 60A containing the metal oxide antibacterial agent of the present invention is excellent in preventing skin troubles. An example of a manufacturing method for manufacturing the fiber 60A containing the metal oxide antibacterial agent 6, in which a large amount of the metal oxide antibacterial agent 6 is located in the fused portion 63, as shown in Fig. 3(A) will be described later.

[0027] The distribution of the metal oxide antibacterial agent 6 located on the surface of a single fiber 60A containing the metal oxide antibacterial agent can be confirmed by subjecting the fiber 60A containing the metal oxide antibacterial agent to SEM-EDX analysis and element mapping. That is, the analysis can confirm that the agent on the fiber surface is zinc oxide (metal oxide antibacterial agent), and can also confirm the amount of zinc oxide contained per unit surface area in each part of the fiber surface (first part, fused part).

[0028] The metal oxide antibacterial agent-containing fiber may be, for example, a single fiber made of one type of synthetic resin (thermoplastic resin) or a blend polymer made by mixing two or more types of synthetic resins, or it may be a composite fiber. The composite fiber referred to here is a synthetic fiber (thermoplastic fiber) obtained by combining two or more types of synthetic resins with different components in a spinneret and spinning them simultaneously, and each of the multiple components has a structure that is continuous in the length direction of the fiber and is mutually bonded within the single fiber. The form of the composite fiber may be a core-sheath type, a side-by-side type, etc.

[0029] From the viewpoint of efficient expression of the antibacterial effect, it is preferable that the metal oxide antibacterial agent 6 is exposed on the surface of the fiber blended with the metal oxide antibacterial agent. From the viewpoint of efficiently exposing the metal oxide antibacterial agent 6 to the fiber surface, it is particularly preferable that the metal oxide antibacterial agent-containing fiber 60A is a sheath-core fiber as shown in Figures 3(A) to 3(C). Moreover, it is preferable that the sheath-core fiber is a concentric sheath-core type in which the sheath and the core are concentrically arranged.

[0030] 3(A) to 3(C), fiber 60A containing a metal oxide antibacterial agent has a core 60C and a sheath 60S. Metal oxide antibacterial agent 6 is contained only in sheath 60S. By containing metal oxide antibacterial agent 6 only in sheath 60S in this way, it is possible to easily expose metal oxide antibacterial agent 6 on the fiber surface with a small content of metal oxide antibacterial agent 6.

[0031] The metal oxide antibacterial agent-containing fiber may be a core-sheath type fiber in which the metal oxide antibacterial agent is kneaded into the sheath portion, or may have the following fiber configuration, for example: That is, the surface of a constituent fiber made of a single fiber or composite fiber may be treated with a hydrophilic oil agent containing the metal oxide antibacterial agent 6 to adhere the metal oxide antibacterial agent 6 to the fiber surface, thereby forming a metal oxide antibacterial agent-containing fiber in which the amount of the metal oxide antibacterial agent per unit surface area in the fused portion is greater than that in the first portion. In order to more effectively prevent the metal oxide antibacterial agent 6 from falling off the fibers, it is more preferable that the metal oxide antibacterial agent 6 is kneaded into the fibers. By kneading the metal oxide antibacterial agent 6 into the fibers, the metal oxide antibacterial agent 6 is less likely to migrate to other layers together with excreted liquid and is more likely to remain in the facing material 2, making it easier to obtain an efficient and effective antibacterial effect.

[0032] As shown in FIGS. 3(B) and (C), in the metal oxide antibacterial agent-containing fiber 60A, the fiber diameter (diameter d63) of the fused portion 63 is preferably larger than the fiber diameter (diameter d61) of the first portion 61. More specifically, the diameter dc63 of the core portion 60C at the fused portion 63 is approximately the same as or slightly larger than the diameter dc61 of the core portion 60C at the first portion 61, and the thickness ds63 of the sheath portion 60S at the fused portion 63 is thicker than the thickness ds61 of the sheath portion 60S at the first portion 61. The metal oxide antibacterial agent-blended fiber 60A having such a configuration can be manufactured by a drawing process described later.

[0033] 3(A), four first regions 61 are located around the fused portion 63, and each first region 61 extends from the fused portion 63. The fused portion 63 becomes a relatively rigid region due to thermal fusion, but the first regions 61, which have a relatively small fiber diameter, are located around the fused portion 63, resulting in a nonwoven fabric with an improved soft texture and feel.

[0034] Here, the first portion 61 is a thin and elongated portion that protrudes from the fused portion 63, and the boundary between the first portion 61 and the fused portion 63 corresponds to the base portion of the first portion 61 extending from the fused portion 63. When viewed in a plan view, the fused portion 63 has a region where the cores of the one fiber of interest and the other fibers overlap, and other regions. In the other regions of the fused portion 63, the portion where the core of the one fiber of interest exists is cut in a cross section perpendicular to the longitudinal direction of the core, and the diameter of the fiber and the thickness of the sheath are respectively defined as the fiber diameter d63 of the fused portion 63 and the thickness ds63 of the sheath 60S of the fused portion 63. In the cross section of the fused portion 63, the core and sheath are not necessarily concentric. Therefore, in a cross section perpendicular to the longitudinal direction of the core, four straight lines are drawn at equal intervals in the rotation direction around the center of the core 60C so as to pass through the center of the core and the contour of the cross section, and the lengths between two intersections of each of the four straight lines and the contour of the cross section are measured, and the average value is taken as the fiber diameter d63 of the fused portion 63 in the fiber of interest. In addition, in the cross section, the thickness of the sheath 60S around the core 60C is measured at four points at equal intervals in the rotation direction around the center of the core 60C, and the average value is taken as the thickness ds63 of the sheath 60S of the fused portion 63 in the fiber of interest.

[0035] In addition, in the fiber 60A containing the metal oxide antibacterial agent, the thickness ds61 of the sheath 60S in the first region 61 is preferably larger than the diameter of the metal oxide antibacterial agent 6. With this configuration, the metal oxide antibacterial agent 6 is not excessively exposed on the surface of the sheath 60S in the first region 61, and the amount of the metal oxide antibacterial agent 6 contained in the first region 61 per unit surface area can be reliably made smaller than that in the fused region 63. This makes it possible to obtain an efficient and effective antibacterial effect by the metal oxide antibacterial agent 6, while maintaining a good balance of bacteria normally present on the skin, resulting in a surface material 2 that is excellent in preventing skin troubles.

[0036] From the standpoint of a good feel on the skin and an efficient antibacterial effect, the thickness ds61 dimension of the sheath portion 60S of the first portion 61 is larger than the diameter of the metal oxide antibacterial agent 6, and the ratio (d61 / d63) of the fiber diameter d61 of the first portion 61 to the fiber diameter d63 of the fused portion 63 is preferably 0.63 or more, more preferably 0.66 or more, and preferably 0.88 or less, and more preferably 0.85 or less, specifically, preferably 0.63 or more and 0.88 or less, and more preferably 0.66 or more and 0.85 or less. Specifically, the fiber diameter d63 of the fused portion 63 is preferably 13 μm or more, more preferably 17 μm or more, and particularly preferably 20 μm or more, and preferably 53 μm or less, more preferably 49 μm or less, and particularly preferably 45 μm or less, and specifically, preferably 13 μm or more and 53 μm or less, more preferably 17 μm or more and 49 μm or less, and particularly preferably 20 μm or more and 45 μm or less. Specifically, the fiber diameter d61 of the first portion 61 is preferably 10 μm or more, more preferably 13 μm or more, and particularly preferably 15 μm or more, and preferably 33 μm or less, more preferably 31 μm or less, and particularly preferably 28 μm or less, and specifically, preferably 10 μm or more and 33 μm or less, more preferably 13 μm or more and 31 μm or less, and particularly preferably 15 μm or more and 28 μm or less.

[0037] Specifically, the diameter dc63 of the core 60C of the fused portion 63 is preferably 6 μm or more, more preferably 8 μm or more, particularly preferably 11 μm or more, and preferably 41 μm or less, more preferably 38 μm or less, particularly preferably 35 μm or less, specifically, preferably 6 μm or more and 41 μm or less, more preferably 8 μm or more and 38 μm or less, particularly preferably 11 μm or more and 35 μm or less. Specifically, the diameter dc61 of the core 60C of the first portion 61 is preferably 6 μm or more, more preferably 8 μm or more, and particularly preferably 10 μm or more, and preferably 27 μm or less, more preferably 25 μm or less, and particularly preferably 23 μm or less, and specifically, preferably 6 μm or more and 27 μm or less, more preferably 8 μm or more and 25 μm or less, and particularly preferably 10 μm or more and 23 μm or less. Specifically, the thickness ds63 of the sheath portion 60S of the fusion portion 63 is preferably 1.0 μm or more, more preferably 1.4 μm or more, and particularly preferably 1.7 μm or more, and preferably 11.2 μm or less, more preferably 8.8 μm or less, and particularly preferably 6.4 μm or less, and specifically, preferably 1.0 μm or more and 11.2 μm or less, more preferably 1.4 μm or more and 8.8 μm or less, and particularly preferably 1.7 μm or more and 6.4 μm or less. Specifically, the thickness ds61 of the sheath portion 60S of the first portion 61 is preferably 0.8 μm or more, more preferably 1.1 μm or more, and particularly preferably 1.3 μm or more, and preferably 7.0 μm or less, more preferably 5.5 μm or less, and particularly preferably 4.0 μm or less, and specifically, preferably 0.8 μm or more and 7.0 μm or less, more preferably 1.1 μm or more and 5.5 μm or less, and particularly preferably 1.3 μm or more and 4.0 μm or less. The method for measuring the dimensions of each component, such as the fiber diameter of the fibers, will be described later.

[0038] [Example 2] In the first example described above, the linear portion 65 of the fiber 60A containing the metal oxide antibacterial agent has a fiber diameter that does not change substantially between one fused portion 63 and the other fused portion 63 of a pair of fused portions 63 that are located with the linear portion 65 interposed therebetween (the linear portion 65 is composed of the first portion 61), but the linear portion 65 may have a portion with a relatively different fiber diameter, as in the fiber 60B containing the metal oxide antibacterial agent in the second example. Note that "fiber diameter does not change substantially" refers to a range in which the ratio (d2 / d1) of the minimum dimension d2 (minimum fiber diameter) to the maximum dimension d1 (maximum fiber diameter) in the width direction relative to the longitudinal direction of the linear portion 65 is greater than 0.9 and less than 1.

[0039] The fiber 60B containing a metal oxide antibacterial agent will be described with reference to Fig. 4. In the following, differences from the first example will be mainly described, and the same components as those in the first example will be given the same reference numerals and description thereof may be omitted. The fiber 60B containing a metal oxide antibacterial agent is also a fiber containing a metal oxide antibacterial agent 6 like the fiber 60A containing a metal oxide antibacterial agent in the first example, and is a core-sheath type fiber in which the metal oxide antibacterial agent is kneaded only in the sheath portion.

[0040] As shown in Figure 4 (A), when focusing on one fiber 60B containing a metal oxide antibacterial agent, the fiber 60B containing a metal oxide antibacterial agent has a plurality of fused parts 63 and a linear part 65 located between two fused parts 63. Furthermore, the linear part 65 has a first part 61B and a second part 62B having relatively different fiber diameters. As shown in Figures 4 (A), (B), and (C), the first part 61B has a smaller fiber diameter than the second part 62B, and the first part 61B can be said to be a small diameter part and the second part 62B can be said to be a large diameter part. As shown in FIG. 4(A), a first portion 61B having a relatively small fiber diameter is located adjacent to a fused portion 63, and a second portion 62B having a relatively large fiber diameter is located between the two first portions 61B.

[0041] 4(A), the fused portion 63 has a greater amount of the metal oxide antibacterial agent 6 per unit surface area than the first portion 61B and the second portion 62B. Furthermore, the second portion 62B has a greater amount of the metal oxide antibacterial agent 6 per unit surface area than the first portion 61B. In other words, when focusing on one fiber 60B containing the metal oxide antibacterial agent, the amount of the metal oxide antibacterial agent 6 per unit surface area is the greatest in the fused portion 63, followed by the second portion 62B, and the least in the first portion 61B. In the second example, as in the first example, the distribution of the metal oxide antibacterial agent 6 located on the surface of a single metal oxide antibacterial agent-containing fiber 60B of interest can be confirmed by subjecting the metal oxide antibacterial agent-containing fiber 60B to SEM-EDX analysis and elemental mapping.

[0042] 4(B) to (D), the fiber diameter d63 of the fused portion 63 is larger than the fiber diameter d61B of the first portion 61B and the fiber diameter (diameter d62B) of the second portion 62B. Furthermore, the fiber diameter d62B of the second portion 62B is larger than the fiber diameter d61B of the first portion 61B. More specifically, the diameter dc63 of the core 60C in the fused portion 63 and the diameter dc62B of the core 60C in the second portion 62B are substantially the same, and the diameter dc63 of the core 60C in the fused portion 63 and the diameter dc62B of the core 60C in the second portion 62B are larger than the diameter dc61B of the core 60C in the first portion 61B. In addition, the thickness ds63 of the sheath 60S in the fused portion 63 is thicker than the thickness ds61B of the sheath 60S in the first portion 61B and the thickness ds62B of the sheath 60S in the second portion 62B. Furthermore, the thickness ds61B of the sheath 60S in the first portion 61B is thinner than the thickness ds62B of the sheath 60S in the second portion 62B. The metal oxide antibacterial agent-blended fiber 60B having such a configuration can be manufactured by a drawing process described later. The boundary between the first region 61B and the second region 62B is a region where the fiber diameter changes suddenly.

[0043] As in the first example, in the fiber 60B containing a metal oxide antibacterial agent, the inter-fiber distance between the linear portions 65 is wider than the inter-fiber distance near the fused portions 63. Therefore, when excrement such as urine or feces is supplied to the surface material 2 of an absorbent article formed using the fiber 60B containing a metal oxide antibacterial agent, the excrement is more likely to accumulate in the fused portions 63. As described above, in the fiber 60B containing the metal oxide antibacterial agent, the fused portion 63 contains a greater amount of the metal oxide antibacterial agent 6 than the first portion 61B and the second portion 62B, and therefore the metal oxide antibacterial agent 6 can be brought into contact with excrement efficiently and frequently, enabling efficient antibacterial action. On the other hand, the amount of the metal oxide antibacterial agent 6 is relatively smaller in the linear portion 65, which is less likely to accumulate excrement than the fused portion 63, and therefore the total amount of the metal oxide antibacterial agent 6 in the surface material 2 can be reduced, and the balance of normal bacteria on the skin can be well maintained. Moreover, in the fiber 60B containing the metal oxide antibacterial agent, the linear portion 65 has a second portion 62B containing a larger amount of the metal oxide antibacterial agent 6 than the first portion 61B, so that the surface material 2 using the fiber 60B containing the metal oxide antibacterial agent of the second example has the metal oxide antibacterial agent 6 distributed over the entire surface of the surface material 2, compared to the surface material using the fiber 60A containing the metal oxide antibacterial agent of the first example. This makes it easier for the antibacterial effect to be exhibited uniformly within the surface, regardless of the distribution of the amount of excrement supplied to the surface material 2.

[0044] Thus, the surface material 2 using the metal oxide antibacterial agent-containing fiber 60B of the present invention has an excellent effect of preventing skin troubles. An example of a manufacturing method for manufacturing the metal oxide antibacterial agent-containing fiber 60B shown in Fig. 4(A), in which the metal oxide antibacterial agent 6 is located in a large amount in the fused portion 63, will be described later.

[0045] Also, as in the first example, from the standpoint of efficient antibacterial effect and maintaining a good balance of normal bacteria on the skin, it is preferable that in the metal oxide antibacterial agent-containing fiber 60B, the thickness ds61B dimension of the sheath portion 60S of the first portion 61B is larger than the diameter dimension of the metal oxide antibacterial agent 6.

[0046] Referring to Figures 4(B) to (D), in fiber 60B containing a metal oxide antibacterial agent, the ratio (d61B / d62B) of the fiber diameter d61B of the first portion 61B to the fiber diameter d62B of the second portion 62B is preferably 0.5 or more, more preferably 0.55 or more, and preferably 0.8 or less, even more preferably 0.7 or less, specifically, preferably 0.5 or more and 0.8 or less, more preferably 0.55 or more and 0.7 or less. Specifically, from the viewpoint of improving the feel on the skin, the fiber diameter d61B of the first portion 61B is preferably 5 μm or more, more preferably 6.5 μm or more, particularly preferably 7.5 μm or more, and preferably 26 μm or less, more preferably 24 μm or less, particularly preferably 22 μm or less, specifically, preferably 5 μm or more and 26 μm or less, more preferably 6.5 μm or more and 24 μm or less, particularly preferably 7.5 μm or more and 22 μm or less. Specifically, the thickness ds61B of the sheath portion 60S of the first portion 61B is preferably 0.4 μm or more, more preferably 0.5 μm or more, and particularly preferably 0.7 μm or more, and preferably 5.6 μm or less, more preferably 4.4 μm or less, and particularly preferably 3.2 μm or less; specifically, it is preferably 0.4 μm or more and 5.6 μm or less, more preferably 0.5 μm or more and 4.4 μm or less, and particularly preferably 0.7 μm or more and 3.2 μm or less. Specifically, the diameter dc61B of the core 60C of the first portion 61B is preferably 3 μm or more, more preferably 4 μm or more, and particularly preferably 5 μm or more, and preferably 22 μm or less, more preferably 20 μm or less, and particularly preferably 18 μm or less, and specifically, preferably 3 μm or more and 22 μm or less, more preferably 4 μm or more and 20 μm or less, and particularly preferably 5 μm or more and 18 μm or less. The specific fiber diameter d63 of the fused portion 63, the diameter dc63 of the core portion 60C, and the thickness ds63 of the sheath portion 60S of the fiber 60B containing the metal oxide antibacterial agent of the second example are similar to those of the fused portion 63 of the fiber 60A containing the metal oxide antibacterial agent of the first example described above. The fiber diameter d62B of the second portion 62B of the fiber 60B containing the metal oxide antibacterial agent of the second example, the diameter dc62B of the core portion 60C, and the thickness ds62B of the sheath portion 60S of the fiber 60B containing the metal oxide antibacterial agent of the second example are similar to the fiber diameter d61 of the first portion 61 of the fiber 60A containing the metal oxide antibacterial agent of the first example described above. The ratio (d62B / d63) of the fiber diameter d62B of the second portion 62B to the fiber diameter d63 of the fused portion 63 of the second example of the metal oxide antibacterial agent-containing fiber 60B is similar to the ratio (d61 / d63) of the fiber diameter d61 of the first portion 61 to the fiber diameter d63 of the fused portion 63 of the first example of the metal oxide antibacterial agent-containing fiber 60A described above. The method for measuring the dimensions of each component, such as the fiber diameter of the fibers, will be described later.

[0047] [Metal oxide antibacterial agents] As the metal oxide antibacterial agent 6, zinc oxide, silver oxide, aluminum oxide, calcium oxide, magnesium oxide, copper oxide, etc. can be used. These metal oxide antibacterial agents may be used alone or in combination of two or more. Among these, it is preferable to use zinc oxide in terms of antibacterial properties, safety, and cost.

[0048] The metal oxide antibacterial agent is preferably poorly soluble or insoluble in water so that the metal oxide antibacterial agent is less likely to migrate to other layers. Here, an example will be given in which poorly water-soluble zinc oxide is used as a metal oxide antibacterial agent. There are various theories about the antibacterial mechanism of zinc oxide. For example, one theory is that zinc ions destabilize the cell membrane of bacteria, inducing cell death, and another is that zinc oxide reacts with water, producing hydrogen peroxide that suppresses the action of bacteria.

[0049] Zinc oxide is poorly soluble in water and therefore does not easily migrate to other layers such as the absorbent body 4 along with the excreted liquid that moves through the surface material 2 in the thickness direction Z, and is therefore likely to remain in the surface material 2. In addition, in the examples shown in Figures 3 and 4, zinc oxide is kneaded into the fibers, and is therefore more likely to remain in the surface material 2.

[0050] The particle size of the metal oxide antibacterial agent 6 is appropriately set in consideration of the thickness of the fibers to which the metal oxide antibacterial agent is mixed and the ease of kneading the metal oxide antibacterial agent into the fibers. In general, the average particle size of the metal oxide antibacterial agent is determined by the volume cumulative particle size D at a cumulative volume of 50% by volume as measured by a laser diffraction / scattering particle size distribution measurement method. 50 It is expressed as 1.0 μm or more and 7 μm or less.

[0051] From the viewpoint of achieving a more pronounced effect of preventing skin rash (skin trouble) caused by feces for a long period of time, the metal oxide antibacterial agent 6 is preferably poorly soluble in water. The solubility in water can be evaluated based on the solubility obtained by the solubility measurement method described below. The solubility of the metal oxide antibacterial agent is preferably 0.01 g / 100 ml or more and 0.5 g / 100 ml or less, more preferably 0.03 g / 100 ml or more and 0.3 g / 100 ml or less, and even more preferably 0.05 g / 100 ml or more and 0.2 g / 100 ml or less.

[0052] (Method for measuring the solubility of metal oxide antibacterial agents) Add 5 g of the metal oxide antibacterial agent to 100 ml of water and stir at 300 rpm for 30 minutes at room temperature (25° C.). Separately, measure the mass of the filter paper and use the measured mass as the initial mass of the filter paper. The stirred solution is filtered using the filter paper whose mass has been measured, and the filter paper is dried in a dryer at 40°C for 2 hours. The mass of the dried filter paper is measured, and the measured mass is regarded as the dried mass of the filter paper. The solubility is then calculated using the following formula. Solubility (g) = 5 (g) - {(mass of dried filter paper) (g) - (initial mass of filter paper) (g)} A higher solubility calculated in this manner indicates a higher solubility in water, and a lower solubility indicates a lower solubility in water.

[0053] [Method for measuring fiber diameter, etc. of fibers containing metal oxide antibacterial agents] The surface material of the measurement object is cut with a razor (e.g., a single-edged razor manufactured by Feather Safety Razor Co., Ltd.) to obtain a measurement piece having a rectangular shape in plan view. When cutting the measurement object, care must be taken so that the structure of the cut surface of the measurement piece formed by the cutting is not destroyed by the pressure during cutting. A preferred method for cutting the measurement object is to place the measurement object in liquid nitrogen prior to cutting and thoroughly freeze it, and then cut it. The test piece is attached to the sample stage using double-sided paper tape (Nichiban Co., Ltd., Uchistack NW-15). The test piece is then platinum-coated. An ion sputtering device E-1030 (product name) manufactured by Hitachi Naka Seiki Co., Ltd. is used for the coating, and the sputtering time is 30 seconds. The cut surface of the test piece is observed at a magnification of 1000 times using a Hitachi S-4000 field emission scanning electron microscope. Using the electron microscope images, the fiber diameters of each of the 10 different constituent fibers at each site (fused portion, first site, and second site) were measured in the width direction relative to the longitudinal direction of the fiber, and the average value of the measured values ​​of the 10 constituent fibers for each site was calculated and used as the fiber diameter for that site. In addition, the diameter of the core and the thickness of the sheath at each portion are measured using electron microscope images of cross sections cut at a plane perpendicular to the longitudinal direction of each portion (fused portion, first portion, and second portion) of each of the 10 different constituent fibers, and the average values ​​of the measured values ​​of the 10 constituent fibers at each portion are calculated and used as the diameter of the core and the thickness of the sheath at each portion. As described above, in the fused portion 63, the core and the sheath are not necessarily concentric in the cross section of a single fiber of interest, so the fiber diameter of the fused portion and the thickness of the sheath at the fused portion of each of the 10 fibers are calculated using the method described above. From the electron microscope image of the cross section of the fiber, it is possible to grasp not only the cross-sectional outline of the fiber but also the fiber structure, for example, whether the fiber is a core-sheath type fiber or a single fiber structure. Furthermore, from the electron microscope image, it is possible to confirm that the metal oxide antibacterial agent is disposed in the sheath portion and that the metal oxide antibacterial agent is exposed on the fiber surface.

[0054] [Relationship between hydrophilicity of fused part and first part] In the fibers 60A and 60B containing the metal oxide antibacterial agent, the fused portion 63 is preferably more hydrophilic than the first portions 61 and 61B. With this configuration, in the surface material 2 including the fiber 60 containing the metal oxide antibacterial agent, excrement is more likely to remain in the fused portion 63, which contains a relatively large amount of the metal oxide antibacterial agent 6, and the metal oxide antibacterial agent 6 can come into contact with the excrement more efficiently and frequently, enabling efficient antibacterial treatment.

[0055] As a method for making the fused portion 63 into a nonwoven fabric having higher hydrophilicity than the first portions 61 and 61B, for example, there is a method of coating the nonwoven fabric with a hydrophilic oil (fiber treatment agent). The hydrophilic oil is a fiber treatment agent that makes the fiber surface hydrophilic. The hydrophilic oil is typically a hydrophilic surfactant. Since the distance between fibers is shorter in the vicinity of the fused portion 63, which is the intersection point between the constituent fibers, the hydrophilic oil is more likely to accumulate in the fused portion 63. By drying the fused portion 63 in a state where a large amount of hydrophilic oil is present, the hydrophilicity of the fused portion 63 can be made higher than that of the first portions 61 and 61B. Furthermore, when the nonwoven fabric is subjected to the stretching process described below, the resin components constituting the sheath portion that were located in the linear portion 65 before the processing are more likely to move and gather at the fused portion 63 due to the stretching process, so that the hydrophilic oil adhering to the resin components gathers at the fused portion 63, thereby further enhancing the hydrophilicity of the fused portion 63.

[0056] The contact angle can be used as an index of hydrophilicity. It can be determined that the smaller the contact angle, the higher the hydrophilicity (lower hydrophobicity), and the larger the contact angle, the lower the hydrophilicity (higher hydrophobicity). In general, the contact angle θ of fibers classified as hydrophilic is 90° or less (preferably 88° or less; the smaller the angle, the higher the hydrophilicity), and the contact angle θ of fibers classified as hydrophobic is more than 90° (preferably more than 90° to 140°).

[0057] (Method of measuring hydrophilicity) The measurement device used is an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. Distilled water is used for contact angle measurement. The amount of liquid discharged from the inkjet type water droplet discharge part (CTC-25 pulse injector manufactured by Cluster Technology Co., Ltd. with a discharge part hole diameter of 25 μm) is set to 20 picoliters, and the water droplets are dropped directly onto the fiber (measurement sample). The dropping state is recorded by a high-speed recording device connected to a camera installed horizontally. From the viewpoint of later image analysis, it is preferable that the recording device be a personal computer equipped with a high-speed capture device. In this measurement, images are recorded every 17 msec. In the recorded video, the first image of the water droplet landing on the fiber is analyzed using the attached software FAMAS (software version 2.62, analysis method is the droplet method, analysis method is the θ / 2 method, image processing algorithm is non-reflective, image processing image mode is frame, threshold level is 200, curvature correction is not performed), and the angle between the surface of the water droplet that is in contact with the air and the fiber is calculated, which is the contact angle. The measurement sample is a fiber obtained by taking it out from the surface material 2. The fiber is placed on the sample stage of the contact angle meter and maintained horizontally, and the contact angle is measured at two different positions for each fiber, at the fusion part and the first part. At the measurement target part, the contact angles of N=5 pieces are measured to one decimal place, and the average value of the measured values ​​at a total of 10 positions (rounded off to two decimal places) is defined as the contact angle at the measurement target part.

[0058] [Examples of materials containing metal oxide antibacterial agents] The raw fiber material for the core-sheath type metal oxide antibacterial agent-blended fiber 60 may have a core 60C made of PET (polyethylene terephthalate) or PP (polypropylene), and a sheath 60S made of PE (polyethylene) kneaded with a metal oxide antibacterial agent (zinc oxide), with a core-sheath ratio of 20 / 80 to 80 / 20 by mass. The core-sheath ratio refers to the mass ratio (core / sheath) of the resins constituting the core and the sheath.

[0059] The manufacturing method will be described later, but the surface material 2 containing the metal oxide antibacterial agent-containing fiber 60 is manufactured, for example, as follows. The raw fibers are used to form a fiber web using a carding machine, and then hot air is blown onto the fiber web using an air-through method to form an air-through nonwoven fabric having fused parts formed by thermal fusion of the intersections of the entangled fibers. The air-through nonwoven fabric is locally stretched using a stretching method described below to produce a surface material 2 having fibers 60 containing a metal oxide antibacterial agent. In the case where the air-through nonwoven fabric is subjected to the stretching process in this manner, it is preferable that the constituent fibers of the air-through nonwoven fabric contain high elongation fibers. The constituent fibers may contain other fibers in addition to the high elongation fibers, but it is preferable that the constituent fibers are composed only of inelastic fibers, and it is more preferable that the constituent fibers are composed only of high elongation fibers.

[0060] Here, the term "high elongation fiber" refers not only to fibers that have high elongation at the stage of raw fiber, but also to fibers that have high elongation at the stage of manufactured nonwoven fabric. Examples of "high elongation fiber" include, except for elastic fibers that have elasticity (elastomer) and stretch, heat-stretchable fibers in which the crystal state of the resin changes due to heating and the length is extended by heating and / or shrinking without stretching, as described in paragraph

[0033] of JP 2010-168715 A, obtained by melt spinning at a low speed to obtain a composite fiber, or fibers manufactured at a relatively low spinning speed using resins such as polypropylene or polyethylene, or fibers manufactured by dry-blending polyethylene with polyethylene-polypropylene copolymer or polypropylene with a low crystallinity and spinning the mixture. Among these fibers, the high elongation fiber is preferably a heat-sheath-core type fiber that is heat-sealable. The sheath-core fiber may be a concentric sheath-core type, an eccentric sheath-core type, a side-by-side type, or an irregular type, but is particularly preferably a concentric sheath-core type. Regardless of the form of the fiber, from the viewpoint of producing a nonwoven fabric or the like that is soft and comfortable to the touch, the fineness of the high elongation fiber in the raw material stage is preferably 1.0 dtex or more, more preferably 2.0 dtex or more, and preferably 10.0 dtex or less, more preferably 8.0 dtex or less, and specifically, preferably 1.0 dtex or more and 10.0 dtex or less, more preferably 2.0 dtex or more and 8.0 dtex or less.

[0061] The elongation of the high elongation fiber in the raw material stage is preferably 100% or more, more preferably 200% or more, even more preferably 250% or more, and is preferably 800% or less, more preferably 500% or less, and even more preferably 400% or less, specifically, it is preferably 100% or more and 800% or less, more preferably 200% or more and 500% or less, and even more preferably 250% or more and 400% or less. By using a high elongation fiber having an elongation in this range, the fiber can be successfully stretched in a stretching device described later, and the fiber is less likely to be broken during stretching.

[0062] The elongation of high elongation fibers is measured in accordance with JISL-1015, based on the following standard conditions: temperature and humidity of the measurement environment is 20±2°C, 65±2% RH, grip interval of the tensile tester is 20 mm, and the tensile speed is 20 mm / min. When fibers are taken from an already manufactured nonwoven fabric to measure elongation, etc., if the length of the fiber to be measured is insufficient to set the grip interval to 20 mm, the grip interval is set to 10 mm or 5 mm and the measurement is made.

[0063] In the high elongation fiber, the resin component constituting the core portion 60C has a higher melting point than the resin component constituting the sheath portion 60S. The resin component constituting the core portion 60C is a component that exhibits thermal extensibility of the fiber, and the resin component constituting the sheath portion 60S is a component that exhibits thermal fusion properties. The resin component constituting the sheath portion 60S includes a polyethylene resin. The resin component constituting the sheath portion 60S is preferably a polyethylene resin alone, but may include other resins. The resin component constituting the core portion 60C may be a resin component having a higher melting point than the polyethylene resin constituting the resin component constituting the sheath portion 60S, such as polypropylene, polyethylene terephthalate, or polybutylene terephthalate. In order to facilitate the production of the nonwoven fabric, it is preferable that the difference between the melting point of the resin component constituting the core and the melting point of the resin component constituting the sheath (the former - the latter) be 20°C or more and 150°C or less.

[0064] Furthermore, in the high elongation fiber, a dispersing material may be contained in the sheath portion 60S. This prevents the metal oxide antibacterial agent 6 kneaded into the sheath portion 60S from locally agglomerating in the sheath portion 60S. By containing a dispersing material, the metal oxide antibacterial agent 6 is uniformly distributed in the sheath portion 60S in the metal oxide antibacterial agent-blended fiber 60 even after the stretching process is performed, and the amount of the metal oxide antibacterial agent per unit surface area in the fused portion 63 can be easily adjusted to be greater than that in the first portions 61 and 61B.

[0065] <Proportion of metal oxide antibacterial agent in surface material> From the viewpoint of efficiently and effectively exerting the skin trouble prevention effect of the metal oxide antibacterial agent 6 and further maintaining the balance of normal bacteria on the skin to suppress skin troubles, the proportion (content) of the metal oxide antibacterial agent in the entire surface material is preferably 0.015 mass% or more and 2.0 mass% or less, and more preferably 0.04 mass% or more and 0.75 mass% or less. A method for calculating the content of the metal oxide antibacterial agent in the surface material will be described below.

[0066] [Method of calculating the content of metal oxide antibacterial agent in surface material] Weigh out 1g of the surface material, chop it into as small pieces as possible, and place it in a 300ml beaker. Add 200ml of ion-exchanged water to the beaker and stir with a magnetic stirrer so that the fibers are completely in contact with the water. While stirring the liquid, gradually add 3ml of concentrated hydrochloric acid (about 10M), and stir for another hour to elute the metal oxide antibacterial agent present on the surface of the fibers that make up the second layer. Next, add 6ml of 5.1M sodium hydroxide aqueous solution to neutralize the liquid, and then add 10ml of a pH 10.7 buffer solution (containing 54.7ml of 28% NH3 aqueous solution and 0.535g of NH4Cl dissolved in ion-exchanged water) to fine-tune the pH. Next, Eriochrome Black T reagent (0.125 g of Eriochrome Black T powder and 1.125 g of hydroxylamine hydrochloride dissolved in 25 ml of absolute ethanol) is added as an indicator to make the liquid pale pink. Titration is performed using 0.0002 M EDTA·2Na as the titrant, and the amount (ml) of titrant added when the liquid changes from pink to pale blue to green is taken as the titration value A. Then, the mass of the metal oxide antibacterial agent is calculated using the following formula. In the formula below, "5000000" means the volume (ml) of titrant per 1 mol. Mass of metal oxide antibacterial agent (g) = titration value A × mass per 1 mol of metal oxide antibacterial agent / 5,000,000 The mass of the metal oxide antibacterial agent calculated as above is the mass of the metal oxide antibacterial agent contained in 1 g of the surface material. Therefore, the calculated mass of the metal oxide antibacterial agent multiplied by 100 is the content of the metal oxide antibacterial agent in the surface material.

[0067] In addition, in the core-sheath type metal oxide antibacterial agent-blended fiber 60 in which the metal oxide antibacterial agent is kneaded only into the sheath portion, the metal oxide antibacterial agent 6 is exposed on the fiber surface, so that the skin trouble prevention effect of the metal oxide antibacterial agent 6 is efficiently and effectively exerted, and from the viewpoint of maintaining a good balance of normal bacteria on the skin, the proportion of the metal oxide antibacterial agent 6 in the resin constituting the sheath portion 60S is preferably 0.1 mass% or more and 5.0 mass% or less, more preferably 0.2 mass% or more and 4.0 mass% or less.

[0068] <Example of overall surface material composition> An example of the form of the surface material 2 used in the diaper 1 will be described. The surface material 2 is configured to include fibers 60 containing a metal oxide antibacterial agent.

[0069] The facing 2 may have an overall flat shape, with the skin side 2a and the non-skin side 2b being flat surfaces, as shown in Fig. 5. In Fig. 5 and Fig. 7 described later, small circles with white outlines inside are schematic representations of fused portions 63 between fibers. In this specification, "flat" means that the surface is flat without any irregularities macroscopically, and the presence of relatively small irregularities that may occur due to the fiber structure is acceptable. For example, irregularities in which the difference between the top of the protrusion and the bottom of the recess in the thickness direction is less than 0.3 mm are acceptable.

[0070] Also, as in the surface material 2 shown in Fig. 6, the skin side surface 2a and the non-skin side surface 2b may have an uneven structure. In the example shown in Fig. 6, the skin side surface 2a has alternating ridge-like convex streaks and groove-like concave streaks extending in one direction, and the skin side surface 2a has an uneven structure having convex portions 33 and concave portions 34. The convex portions 33 are formed to protrude toward the skin side, and concave portions 34 that are concave toward the non-skin side are formed between the convex portions 33. The non-skin side surface 2b has groove-like concave portions corresponding to the convex streaks of the skin side surface 2a, and ridge-like convex streaks corresponding to the concave portions of the skin side surface 2a, and the non-skin side surface 2b also has an uneven structure.

[0071] The surface material 2 may also be constructed by laminating a plurality of nonwoven fabric layers, and may have a laminated structure of an upper layer UL and a lower layer LL, for example, as shown in Fig. 7. The surface material 2 shown in Fig. 7 can be manufactured by overlapping a nonwoven fabric that serves as the upper layer UL and is composed of fibers 60 containing a metal oxide antibacterial agent, and a nonwoven fabric that serves as the lower layer LL and is composed of fibers 70 having a plurality of fused portions 71 that do not contain an antibacterial agent, and partially bonding these nonwoven fabrics. In the surface material 2 shown in Fig. 7, the upper layer UL constituting the skin side surface 2a is a nonwoven fabric layer having an uneven structure, and has recesses 34 and protrusions 33. The uneven structure of the upper layer UL may be in a form in which ridge-like protrusions and groove-like recesses are alternately arranged as shown in Fig. 6, or in a form in which a plurality of protrusions 33 and a plurality of recesses 34 are formed in a staggered pattern, and the shapes and arrangements of the protrusions 33 and recesses 34 are not particularly limited. The lower layer LL constituting the non-skin side 2b is a generally flat nonwoven fabric layer as shown in FIG. In the surface material 2 shown in FIG. 7, the upper layer UL is a layer that contacts the wearer's skin and is a layer to which excrement is directly supplied. Therefore, by forming the upper layer UL from the fiber 60 containing a metal oxide antibacterial agent and forming the lower layer LL from the fiber 70 containing no antibacterial agent, the metal oxide antibacterial agent 6 can be efficiently and frequently brought into contact with excrement even with a small amount of the metal oxide antibacterial agent 6 overall, enabling efficient antibacterial treatment and maintaining a good balance of resident bacteria. In addition, costs can be reduced. Furthermore, in the recesses 34 of the upper layer UL, the recessed shape makes it easy for excrement to remain, so that the metal oxide antibacterial agent 6 can be brought into contact with excrement more efficiently and frequently. The surface material 2 may be configured by laminating a plurality of generally flat nonwoven fabric layers, or may be configured by laminating a plurality of nonwoven fabric layers having an uneven structure.

[0072] In this way, the surface material 2 can take various forms, and it is sufficient that at least the skin side 2a of the surface material 2 contains the metal oxide antibacterial agent-containing fiber 60. By containing the metal oxide antibacterial agent-containing fiber 60 on the skin side 2a of the surface material 2 that contacts the wearer's skin, an antibacterial effect can be exerted from the early stage of excretion, and the proliferation of bacteria caused by the wearer's excrement is suppressed from the early stage of excretion, thereby suppressing skin troubles.

[0073] In addition, as shown in Figures 6 and 7, by making the skin side 2a that comes into contact with the wearer's skin when worn, an uneven structure, the stickiness and stuffiness caused by the skin side 2a coming into full contact with the skin, and the irritation caused by chafing are reduced, further suppressing skin problems such as inflammation, eczema, and skin rashes.

[0074] <Method of manufacturing surface material> A manufacturing example of a fiber 60 containing a metal oxide antibacterial agent in which the metal oxide antibacterial agent 6 is distributed relatively more in the fused portion 63 will be described below.

[0075] [Manufacturing method example 1] A nonwoven fabric including metal oxide antibacterial agent-containing fibers 60 in which the metal oxide antibacterial agent 6 is distributed in a large amount locally (specifically, in the fused portion) can be manufactured, for example, as follows. First, a nonwoven fabric is formed by the air-through method using raw fibers having a core-sheath structure in which the metal oxide antibacterial agent 6 is kneaded only in the sheath portion. The air-through nonwoven fabric has a plurality of fused portions 63 formed by thermal fusion at the intersections of the fibers. Next, as shown in Fig. 8, the air-through nonwoven fabric is sandwiched between two intermeshing uneven rolls 11 and 12 having uneven shapes on their peripheral surfaces of a stretching device 20. This causes the air-through nonwoven fabric to be intermittently stretched (stretching process), and a nonwoven fabric having an appearance such as that shown in Fig. 6 can be obtained. The uneven roll 11 is formed with large diameter convex portions 13 and small diameter concave portions 15 alternately arranged in the circumferential direction of the roll. The uneven roll 12 is formed with large diameter convex portions 14 and small diameter concave portions 16 alternately arranged in the circumferential direction of the roll. The uneven rolls 11 and 12 are capable of meshing with each other and are configured to be heatable. As shown in Fig. 8, the nonwoven fabric 10 after the stretching process has the tops 21 of the convex portions 33 that protrude upward, the bottoms 22 of the concave portions 34 that are recessed downward, and the wall portions 23 located between the tops 21 and the bottoms 22. The wall portions 23 are the areas that are mainly stretched by the stretching process, while the tops 21 and the bottoms 22 are areas that are not stretched very much. In this way, the air-through nonwoven fabric is partially stretched in the stretching process.

[0076] Here, the fused portion 63 is a portion that is difficult to stretch by the stretching process due to being thermally fused. Therefore, of the linear portion 65 located between the two fused portions 63 before the stretching process, the portion adjacent to the fused portion 63 is easily tensioned by the stretching process and is easily stretched. Therefore, in the nonwoven fabric 10 after the stretching process, in the fiber in the region stretched by the stretching process, the portion of the linear portion 65 adjacent to the fused portion 63 is stretched to form the first portions 61 and 61B, and the component resin of the sheath of this stretched portion (resin in which the metal oxide antibacterial agent is kneaded) moves to gather at the fused portion 63. As a result, the first portions 61 and 61B with a relatively thin sheath are formed, and the thickness of the sheath of the fused portion 63 becomes thick, and the fiber 60 containing the metal oxide antibacterial agent becomes a fiber in which the metal oxide antibacterial agent 6 is distributed relatively more in the fused portion 63. In this way, the stretching process can provide fiber 60 containing a metal oxide antibacterial agent, in which metal oxide antibacterial agent 6 is distributed relatively more in fused portions 63. Furthermore, in the fiber in the region stretched by the stretching process, the length of linear portion 65 becomes longer than before the process, and therefore nonwoven fabric 10 can be obtained with improved breathability and liquid permeability.

[0077] In addition, the shape of the linear portion 65 may be adjusted by adjusting the number of fused portions in the air-through nonwoven fabric before processing or the stretch ratio during stretch processing. For example, by increasing the number of fused portions 63 in the air-through nonwoven fabric before stretching, the distance between two fused portions 63 can be shortened, and the air-through nonwoven fabric in this state can be stretched at a high stretch ratio to easily obtain a fiber 60A containing a metal oxide antibacterial agent having linear portions 65 having only first portions 61 without second portions 62B as shown in Figure 3(A). On the other hand, by reducing the number of fused parts 63 of the air-through nonwoven fabric before stretching, the distance between two fused parts 63 is increased, and the air-through nonwoven fabric in this state is stretched at a general stretch ratio to easily obtain a metal oxide antibacterial agent-containing fiber 60B having a linear part 65 having a first part 61B and a second part 62B as shown in Fig. 4(A). The first part 61B is a part that has been stretched by stretching. The second part 62B is a part that has not been stretched by stretching, and has the same fiber diameter as the linear part 65 before stretching. In addition, since the fused parts of the air-through nonwoven fabric are not regularly positioned but are formed in a mesh shape of random size, not all of the stretched regions of the nonwoven fabric 10 after the stretching process necessarily have the form of the fiber 60A containing the metal oxide antibacterial agent of the first example or the fiber 60B containing the metal oxide antibacterial agent of the second example, and both may be mixed. Also, as in the fiber 60B containing the metal oxide antibacterial agent of the second example shown in Fig. 4(A), the fiber may have a form including a linear portion 65 including three first portions 61B and two second portions 62B, and a linear portion 65 including two first portions 61B and one second portion 62B. However, by adjusting the number of fused parts in the air-through nonwoven fabric and the stretch ratio during stretching, it is possible to make adjustments such as making a nonwoven fabric having a higher overall content of metal oxide antibacterial agent-containing fiber 60A as in the first example, or making a nonwoven fabric having a higher overall content of metal oxide antibacterial agent-containing fiber 60B as in the second example.

[0078] During the stretching process, the uneven rolls 11 and 12 may or may not be heated, but it is more preferable to heat the uneven rolls 11 and 12. By heating, the resin component of the sheath portion in which the metal oxide antibacterial agent 6 is disposed, which was in the linear portion 65 before the stretching process, melts and moves in even greater amount to the fused portion 63, so that more of the metal oxide antibacterial agent 6 is positioned in the fused portion 63.

[0079] From the viewpoint of facilitating drawing of the high elongation fibers contained in the constituent fibers, the heating temperature when heating the uneven rolls 11, 12 is preferably set to a temperature equal to or higher than the glass transition point of the resin with the highest glass transition point in the high elongation fibers and equal to or lower than the melting point of the resin with the lowest melting point in the high elongation fibers, more preferably, equal to or higher than a temperature 10°C higher than the glass transition point of the fibers and equal to or lower than a temperature 10°C lower than the melting point, and even more preferably, equal to or higher than a temperature 20°C higher than the glass transition point of the fibers and equal to or lower than a temperature 20°C lower than the melting point.

[0080] In this way, by locally stretching the air-through nonwoven fabric by stretching processing, it is possible to obtain a nonwoven fabric 10 having metal oxide antibacterial agent-blended fibers 60 in which the metal oxide antibacterial agent 6 is distributed in relatively large amounts in the above-mentioned fused portions 63, and this nonwoven fabric 10 can be used to form a surface material 2.

[0081] For example, as shown in FIG. 7, a surface material 2 can be formed by laminating and partially joining a nonwoven fabric 10 having a concave-convex structure that has been subjected to a stretching process as an upper layer UL and a nonwoven fabric having a flat structure as a lower layer LL. 5, the nonwoven fabric 10 having been given an uneven shape by the stretching process may be stretched into a flat shape to form the surface material 2. Even when stretched into a flat shape in this manner, the shape of the metal oxide antibacterial agent-blended fiber 60 in which the metal oxide antibacterial agent 6 is distributed relatively more in the fused portion 63 is maintained. Moreover, the nonwoven fabric 10 having the uneven shape formed by the above-mentioned stretching process may be used alone as the surface material 2, as shown in Fig. 6. However, from the viewpoint of maintaining the uneven shape of the surface material 2 in a good condition, it is preferable to use a configuration in which the uneven nonwoven fabric layer (upper layer UL in Fig. 7) is supported by another nonwoven fabric layer (lower layer LL in Fig. 7) as shown in Fig. 7.

[0082] As described above, it is preferable that the thicknesses ds61 and ds61B of the sheath portion 60S of the first portions 61 and 61B are larger than the diameter dimension of the metal oxide antibacterial agent 6, and this configuration can be achieved by adjusting the stretch ratio during the stretching process.

[0083] [Manufacturing method example 2] Another example of the production of a metal oxide antibacterial agent-containing fiber in which the metal oxide antibacterial agent 6 is distributed relatively more in the fused portion 63 will be described.

[0084] An air-through nonwoven fabric is formed by an air-through manufacturing method using raw fibers with a core-sheath structure that do not contain a metal oxide antibacterial agent 6. The air-through nonwoven fabric has multiple fused parts where the intersections between the fibers are thermally fused. A hydrophilic oil agent (fiber treatment agent) containing a metal oxide antibacterial agent is applied to the air-through nonwoven fabric. The applied hydrophilic oil agent is concentrated in the fused parts due to the capillary force of the fibers. By drying this, a nonwoven fabric for a surface material can be produced that contains fibers containing a metal oxide antibacterial agent, in which the metal oxide antibacterial agent 6 is distributed relatively in large amounts on the surface of the fused parts.

[0085] <Other embodiments> 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.

[0086] 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, for example, a urine pad, a panty liner, a sanitary napkin, etc., and the surface material of the present invention can be used as the surface material of these absorbent articles. Absorbent articles are generally composed of a liquid-permeable surface material, a liquid-impermeable backing material, and a liquid-retentive absorbent interposed between the two sheets.

[0087] In each of the above-mentioned embodiments, the metal oxide antibacterial agent-containing fiber may contain antibacterial agents other than the metal oxide antibacterial agent, such as surfactants and organic compounds.

[0088] The metal oxide antibacterial agent-containing fiber may also contain a skin care agent. As the skin care agent, a hydrophobic skin care agent, a hydrophilic skin care agent, etc. can be used.

[0089] A hydrophobic skin care agent is a hydrophobic component that is not water-soluble or water-dispersible or has extremely low solubility, and is a composition or compound that has protective, healing, etc. effects on the wearer's skin. More specifically, a hydrophobic component is one 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 left to stand for 24 hours, preferably one that dissolves in an amount of 0.1 g or less, and particularly preferably one that does not dissolve at all. Examples of hydrophobic skin care agents include fatty acids with a carbon chain length of 12 to 28 or ester compounds of the fatty acids and glycerin, wax, petrolatum, etc., and in particular, it is preferable to contain unsaturated fatty acids with a carbon chain length of 12 to 28 or glycerin ester compounds of the unsaturated fatty acids. The glycerin ester is a monoester, diester, or triester of glycerin and the above-mentioned unsaturated fatty acid, and in particular, it is preferable to use a triester. As agents containing fatty acids or fatty acid compounds, natural product extracts such as argan oil and shea butter can be preferably used. In particular, argan oil, which is a hydrophobic vegetable oil containing unsaturated fatty acids, maintains the balance between moisture and oil in the skin, prevents dryness, and functions as a skin care agent. In addition, argan oil contains a lot of unsaturated fatty acids such as oleic acid and linoleic acid, and has a strong ability to remove active oxygen, and can reduce skin damage caused by, for example, sunburn.

[0090] On the other hand, a hydrophilic skin care agent is 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 is one that dissolves or disperses in an 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 one that dissolves or disperses in an amount of 5 g or more, more preferably one that dissolves in an amount of 1 g or more, even more preferably one that dissolves in an amount of 5 g or more, and most preferably one that dissolves completely. As the hydrophilic skin care agent, natural product extracts such as peach leaf extract and witch hazel extract, polyhydric alcohols having 2 to 4 carbon chains, 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 surface material and transfers to the skin, providing a skin care effect. A polyhydric alcohol having 2 to 4 carbon chains is a hydrophilic component, typically 1,3-butylene glycol. The use of 1,3-butylene glycol improves moisturizing effect and lubricity. The improved lubricity reduces friction between the skin and the nonwoven fabric, suppressing damage to the skin. 1,3-butylene glycol is a moisturizing liquid water-soluble base component that has a smooth feel and is less sticky, and keeps the skin moist. 1,3-butylene glycol is used as a moisturizing agent and also as a solvent. For example, when peach leaf extract is used as a skin care agent, 1,3-butylene glycol can be used as a solvent for peach leaf extract. Here, 1,3-butylene glycol is taken as an example, but any polyhydric alcohol having 2 to 4 carbon chains will have the same effect, and for example, propylene glycol may be used. Propylene glycol can also be used as an extraction solvent for peach leaf extract (hydrophilic extract). [Explanation of symbols]

[0091] 1...Disposable diapers (absorbent articles) 2...Surface material (surface material of absorbent articles) 6. Metal oxide antibacterial agents 60, 60A, 60B...Metal oxide antibacterial agent blended fiber (constituent fiber) 61, 61B…Part 1 63...Fusion part 65...Linear area

Claims

1. A surface material for an absorbent article having a plurality of fused portions formed by heat-sealing intersections of constituent fibers, The constituent fibers have a metal oxide antibacterial agent on the surface thereof, When one of the constituent fibers is focused on, the constituent fiber has a linear portion between two of the fused portions, and the linear portion includes a first portion extending from the fused portion, The fused portion has a larger amount of the metal oxide antibacterial agent per unit surface area than the first portion. Surface material for absorbent articles.

2. The proportion of the metal oxide antibacterial agent blended in the surface material is 0.015% by mass or more and 2.0% by mass or less. The surface material of the absorbent article according to claim 1.

3. The metal oxide antibacterial agent is kneaded into the constituent fibers. The surface material of the absorbent article according to claim 1.

4. The constituent fibers are core-sheath fibers having a core and a sheath, the metal oxide antibacterial agent is blended in the sheath, and the metal oxide antibacterial agent is exposed on the surface of the constituent fibers. The surface material of the absorbent article according to claim 1.

5. The thickness of the sheath portion of the first portion of the constituent fiber is greater than the diameter of the metal oxide antibacterial agent. The surface material of an absorbent article according to claim 4.

6. The hydrophilicity of the fused portion is higher than the hydrophilicity of the first portion. The surface material of the absorbent article according to claim 1.

7. The linear portion is The first portion; a second region having a larger blending amount of the metal oxide antibacterial agent per unit surface area than the first region; have The surface material of the absorbent article according to claim 1.

8. The fused portion has a larger amount of the metal oxide antibacterial agent per unit surface area than the second portion. The surface material of an absorbent article according to claim 7.

9. Has an uneven surface on the skin side The surface material of the absorbent article according to claim 1.

10. The metal oxide antimicrobial agent is zinc oxide. The surface material of the absorbent article according to claim 1.

11. It has a skin side, The constituent fibers containing the metal oxide antibacterial agent are present at least on the skin side. The surface material of the absorbent article according to claim 1.

12. An absorber; a surface material of the absorbent article according to any one of claims 1 to 11, which is located on the skin side of the absorbent body; An absorbent article comprising:

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