Hygienic mask sheets

Abstract

To provide a sheet for a sanitary mask which has stretchability and can maintain high collectability of particles or the like in air before and after being stretched.SOLUTION: In a sanitary mask sheet having stretchability in at least one direction, a shrinkage ratio of the sheet at a position where a width in an axial direction orthogonal to the one direction is narrowest when elongated from an initial length by a length of 50% of the initial length in the one direction, is within 10%.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a sheet for a sanitary mask. [Background technology]

[0002] Sanitary masks are used to cover a person's mouth and nose to prevent airborne particles (such as dust, dirt, pollen, and droplets containing viruses) from entering from the outside. The purpose of using such sanitary masks also includes preventing droplets containing viruses, etc. from spreading from the mouth or nose to the outside. Various technologies have been proposed for such sanitary masks. For example, Patent Document 1 describes a face mask including an elastic sheet and a filtering web attached to the outer surface of the elastic sheet, the filtering web having folds parallel to the longitudinal direction of the face mask and vertical pleats that are expandable when the face mask is used. Patent Document 2 describes a mask body having a corrugated filtering structure with valleys and ridges and elastic bridge filaments. In the mask body, the elastic bridge filaments are arranged to bridge multiple ridges of the corrugated filtering structure, thereby suppressing local deformation of the ridges. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2015-527500 [Patent Document 2] Special Publication No. 2018-500467 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, conventional sanitary masks can have gaps between the mask and the skin when in use, and further improvements in fit are desired. To improve the fit, there are sanitary masks that have elasticity. However, the shape of the sanitary mask may change due to the elasticity, which may actually impair the fit. In particular, sanitary masks that have elasticity in the direction from the wearer's mouth to the ears are prone to deformation, such as a reduction in the width of the sanitary mask along the direction connecting the wearer's nose, mouth, and chin. The deformation of the sanitary mask leads to a reduction in the protection area for the wearer's nose and mouth, and there is room for improvement in terms of fully expressing the sanitary mask's function of collecting particles in the air. In addition, deformation of the sanitary mask due to stretching may cause changes in the filter structure that realizes the collection function of the sanitary mask. Therefore, it is strongly desired that the collection ability of the sanitary mask be maintained at a high level even before and after tensioning by stretching the sanitary mask.

[0005] In view of the above, the present invention relates to a sheet for sanitary masks that has stretchability while at the same time maintaining high collection ability for airborne particles and the like before and after tensioning. [Means for solving the problem]

[0006] The present invention provides a sheet for sanitary masks that has elasticity in at least one direction, and when stretched in said one direction by 50% longer than its initial length, the shrinkage rate at the position where the width in the axial direction perpendicular to said one direction is narrowest is within 10%.

[0007] The present invention also provides a sheet for sanitary masks, comprising a base sheet having elasticity in at least one direction and a nonwoven fabric having a ridge-and-groove pattern and a tensile modulus higher than that of the base sheet, the nonwoven fabric having ridges and grooves arranged alternately on the surface of the base sheet.

[0008] The present invention further provides a method for producing a sheet for a sanitary mask, in which a textured nonwoven fabric having alternating convex portions and concave portions arranged in a ridge-groove pattern and having a higher tensile modulus than that of a base sheet having elasticity in at least one direction is laminated on the surface of the base sheet, the method comprising the steps of: laminating a flat raw nonwoven fabric before the textured nonwoven fabric is formed into the textured shape, while stretching the base sheet along the stretch direction of the base sheet to between 40% and 99% of its breaking elongation rate; forming joints that integrate the base sheet and the raw nonwoven fabric in a direction perpendicular to the stretch direction at locations of the raw nonwoven fabric that will become the concave portions, the joints forming the joints between the base sheet and the raw nonwoven fabric; and shrinking the raw nonwoven fabric by returning the base sheet to its natural state, thereby forming a textured nonwoven fabric having alternating convex portions and concave portions formed in a ridge-groove pattern on the surface of the base sheet. Effect of the Invention

[0009] The sheet for sanitary masks of the present invention has stretchability while at the same time maintaining high collection ability for airborne particles and the like before and after tension. According to the method for producing a sheet for sanitary masks of the present invention, the sheet for sanitary masks described above can be suitably produced. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1A is an exploded perspective view showing an apparatus for measuring particle collection efficiency, and FIG. 1B and FIG. 1C are cross-sectional perspective views of an upper jig and a lower jig in the apparatus shown in FIG. [Diagram 2] FIG. 1 is a perspective view showing an example of a preferred embodiment of a sheet for sanitary masks according to the present invention. [Diagram 3] 3A and 3B are perspective views showing an example of the behavior of the sheet for sanitary masks shown in FIG. 2 in a contracted state, and FIG. 3B shows the extended state. [Figure 4] FIG. 3 is an explanatory diagram showing an example of a stress-strain curve when the sheet for sanitary masks shown in FIG. 2 is stretched in the longitudinal direction. [Diagram 5]FIG. 3(A) is a cross-sectional view of the sheet for sanitary masks shown in FIG. 2, and FIG. 3(B) is a cross-sectional view showing a modified example of the sheet for sanitary masks shown in FIG. [Figure 6] 1(A) and (B) are explanatory diagrams showing a method for measuring the ratio of the surface area of ​​a rugged nonwoven fabric per unit area in a planar projection view of a sheet for a sanitary mask. [Figure 7] FIG. 2 is a perspective view showing an example of the arrangement of joints between a concave-convex nonwoven fabric and a base sheet. [Figure 8] FIG. 2 is a partially cutaway perspective view showing an example of a stretchable sheet used as a base sheet. [Figure 9] 9 is a plan view showing a biting stretched portion in the elastic sheet shown in FIG. 8. FIG. [Figure 10] FIG. 4 is a plan view showing another example of a stretchable sheet. [Figure 11] FIG. 3 is an explanatory diagram showing an example of a method for producing the sheet for sanitary masks shown in FIG. 2. [Figure 12] 1 is a graph showing the results of tensile tests of Examples and Comparative Examples. [Figure 13] 13 is a graph showing an enlarged portion of the test results shown in FIG. 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described below based on its preferred embodiments. The present invention relates to a sheet material used for a sanitary mask (hereinafter referred to as a sheet for a sanitary mask). In this specification, a "sanitary mask" refers to a member that is worn on a person's face for breathing, and filters air before it is inhaled into the person's respiratory organs, and filters the breath and droplets exhaled by the person before they are expelled to the outside. Therefore, the sheet for a sanitary mask according to the present invention preferably has a size and shape sufficient to cover at least a person's mouth and nose.

[0012] The sheet for sanitary masks of the present invention has elasticity in at least one direction. When the sheet for sanitary masks of the present invention is stretched in the one direction by 50% longer than the initial length, the shrinkage rate at the position where the width in the axial direction perpendicular to the one direction is narrowest (width shrinkage rate at 50% stretch) is within 10%. The shrinkage rate is defined by the following formula (S1). Shrinkage rate (%) = [{(axial length before elongation) - (axial length after elongation)} / (axial length before elongation)] × 100 (%) (S1)

[0013] As a result, the sheet for sanitary masks of the present invention has a structure that is difficult to shrink in a direction perpendicular to one direction in which it has elasticity. In other words, even if it is stretched by pulling in the one direction, the occurrence of width shrinkage in the direction perpendicular to the one direction is suppressed, so it is difficult to lose its shape and has excellent shape retention of the sheet surface.

[0014] The "one direction" having the above-mentioned elasticity is preferably a direction connecting the mouth and the left and right ears of the wearer in the sanitary mask, i.e., a direction set as the horizontal direction of the sanitary mask. The "axial direction" perpendicular to this is preferably a direction that is the vertical central axis of the protective area of ​​the sanitary mask that covers the wearer's nose, mouth, and chin when applied to the sanitary mask. When the above-mentioned direction is used, the sanitary mask obtained from the sheet for sanitary masks of the present invention has elasticity in the horizontal direction connecting the wearer's mouth and the left and right ears, and when stretched, the width shrinkage in the vertical direction covering the wearer's nose, mouth and chin is suppressed. As a result, the obtained sanitary mask fits the wearer's face well and suppresses the occurrence of gaps. At the same time, the protective area for the nose and mouth can be sufficiently secured, and the sanitary mask's function of collecting particles in the air can be fully expressed.

[0015] The sheet for sanitary masks of the present invention is not limited to being stretchable in only one direction within the sheet plane, but may also be stretchable in other directions intersecting therewith, and may be stretchable in multiple directions including the one direction. When the sheet is stretchable in multiple directions within the sheet plane, the direction with the longest breaking elongation is defined as the "one direction" in which the sheet is stretchable, and this is set as the horizontal direction of the sanitary mask, and the direction perpendicular to this is the axial direction. Typically, when the sheet for sanitary masks of the present invention has a longitudinal direction and a transverse direction, and the longitudinal direction is the "one direction" in which the sheet is stretchable, the longitudinal direction is the transverse direction of the sanitary mask, and the transverse direction is the vertical direction of the sanitary mask. In the embodiment described below, the longitudinal direction of the sheet 10 for sanitary masks is the aforementioned stretchable direction, and the transverse direction is the axial direction. However, the present invention is not limited to this, and the stretchable direction and the axial direction perpendicular thereto can be appropriately set within the sheet plane.

[0016] (Method of measuring shrinkage rate) The shrinkage rate can be calculated by measuring the axial width before and after elongation by the following method and applying the obtained measured value to the above-mentioned formula (S1). First, cut a test piece from a sheet for a sanitary mask in its natural state to a size of 50 mm in one direction in which it has elasticity and 25 mm in the axial direction. When cutting a test piece from a sanitary mask to evaluate it, the direction in which it stretches the most, such as the vertical direction of the mask (from the nose to the chin) or the horizontal direction (from the mouth to the ears), is used as the pulling direction for evaluation. Set the test piece in the tensile tester so that the gauge length is 40 mm. For example, hold the upper end of the test piece 5 mm in the upper test piece chuck of the tensile tester, and the lower end 5 mm in the lower test piece chuck, and set it so that the gauge length is 40 mm. When setting, the direction in which the test piece has elasticity is the direction between the test piece chucks. A typical tensile tester can be used for the tensile test. The test is performed at a temperature of 23°C and a humidity of 50% RH. The tensile speed is set to 100 mm / min. Start the tensile test, and when the gauge length becomes 60 mm (when the specimen is stretched by 50% in one direction of elasticity), measure the width of the specimen at the position where the width in the axial direction of the specimen is narrowest. Any measuring means can be used as long as it can measure length. For example, a ruler can be used. If the measurement result shows that the shrinkage rate calculated using the above formula is 10% or less, it is determined that the shrinkage rate standard is met.

[0017] In the sheet for sanitary masks of the present invention, from the viewpoint of suppressing width shrinkage due to stretching and improving the shape retention of the sheet surface, the shrinkage rate at the position where the axial width is narrowest when stretched 50% in one stretchable direction is preferably 8% or less, and more preferably 5% or less. The smaller the axial shrinkage rate of the sheet for sanitary masks of the present invention is, the more preferable it is, and the lower limit thereof is 0%.

[0018] From the viewpoint of suppressing the width shrinkage and maintaining the shape of the sheet surface, the sheet for sanitary masks of the present invention preferably does not shrink in the axial direction when stretched 50% in one stretchable direction, i.e., it is preferable that the sheet is non-shrinkable in the axial direction when stretched 50% in one stretchable direction.

[0019] In this specification, "elastic" refers to the property of being stretched in one direction by 50% longer than the initial length, and then shrinking to a length 10% longer than the initial length or less when the force of pulling in one direction is removed. In other words, when the initial length is taken as 100, the sheet is stretched in one direction to a length of 150 with respect to the reference length of 100, and then the force is removed to return to a length of 100 to 110. "Inelastic" refers to the property of not being able to stretch to a length of 150, or of not being able to return to a length of 100 to 110 when the force is removed even if the sheet can be stretched.

[0020] The sheet for sanitary masks of the present invention has a high collection rate for particles in the air as a material for forming a sanitary mask. As a filter structure with a high collection rate, the sheet for sanitary masks of the present invention preferably has a fiber sheet with a fiber network structure, a porous sheet using a polyurethane material, or a combination thereof. The sheet for sanitary masks of the present invention may be composed of a single layer or multiple layers. When the sheet for sanitary masks of the present invention includes the above-mentioned fiber sheet, it is advantageous to, for example, reduce the thickness of the fibers, thereby shortening the distance between the fibers. The fiber network structure in the fiber sheet is formed by entanglement or bonding of the fibers, or a combination thereof, thereby maintaining the shape of the sheet. Such a fiber sheet can improve the collection rate of fine particles in the air for the above-mentioned filtration by shortening the distance between fibers and complicating the passage of particles. The porous sheet can improve the collection rate of fine particles and the like in the air for the above-mentioned filtration due to the air bubble structure made of polyurethane material. The air filtering effect of the sheet for sanitary masks of the present invention is exerted by preventing the passage of foreign matter in the air as the air passes through the spaces defined by the fibers or polyurethane material that constitute the sheet.

[0021] As the fiber sheet, various materials that can be commonly used in sanitary masks can be used, such as nonwoven fabric. As the nonwoven fabric, various types can be used as long as the above-mentioned characteristics of the sheet for sanitary masks of the present invention are not impaired. For example, nonwoven fabrics obtained by the meltblown method (meltblown nonwoven fabric), nonwoven fabrics obtained by the electrospinning method (electrospinning nonwoven fabric), nonwoven fabrics obtained by the spunbond method (spunbond nonwoven fabric), nonwoven fabrics produced by the air-through method (air-through nonwoven fabric), nonwoven fabrics produced by the spunlace method (spunlace nonwoven fabric), or nonwoven fabrics produced by the needlepunch method (needlepunch nonwoven fabric), or laminates of two or more of these nonwoven fabrics, or laminates of these nonwoven fabrics with other nonwoven fabrics or other materials, etc. are mentioned. Among them, spunbond nonwoven fabrics and needlepunch nonwoven fabrics are preferred. These spunbond nonwoven fabrics and needlepunch nonwoven fabrics have higher strength and cushioning than other types of nonwoven fabrics, and are particularly preferred as protective materials that increase the strength of the sheet for sanitary masks of the present invention. The nonwoven fabric may also contain an elastic material as described below. The resin constituting these nonwoven fabrics is not particularly limited in type as long as it has fiber-forming ability. For example, polyolefin resin or polyester resin can be used. In addition, it is preferable to include thermoplastic fibers from the viewpoint of forming various fused parts such as the joining points 21 of the sanitary mask described later.

[0022] When the sheet for sanitary masks of the present invention includes the above-mentioned fiber sheet or porous sheet, the shrinkage rate in the axial direction is suppressed, so that the fiber network structure or the air bubble structure is less likely to be deformed or crushed. This allows the internal filter structure to be maintained before and after tensioning to stretch the sheet for sanitary masks of the present invention, and the above-mentioned collection ability can be maintained at a high level. In addition, by suppressing the axial shrinkage rate, it is possible to prevent unintended deformation of the sanitary mask shape, which could result in a small change in the coverage area of ​​the face, or a change in the adhesion of the sanitary mask to the skin.

[0023] Such a sheet for sanitary masks of the present invention exhibits a high collection efficiency for airborne particles, and preferably has a collection efficiency for particles having a particle diameter of more than 1 μm of 85% or more. By having a particle collection rate of 85% or more for particles with a particle size of more than 1 μm, it is possible to effectively prevent people from inhaling dust, dirt, pollen, droplets containing viruses, etc. At the same time, by having the above-mentioned high collection rate, the sheet for sanitary masks of the present invention can effectively prevent people from diffusing exhaled breath and droplets to the outside. From the viewpoint of further enhancing the above-mentioned effect, the collection rate is preferably 88% or more, and more preferably 90% or more. The higher the particle collection rate, the higher the collection performance, and a rate of 100% or less is realistic.

[0024] (Method for measuring collection efficiency of particles with a particle size of 1 μm or more) Using a handheld airborne particle counter (MET ONE HHPC6+ manufactured by Beckman Coulter, Inc.), the sheet to be evaluated is fixed so that the measurement terminal of the counter is blocked by the sheet. At this time, it is necessary to seal the gap between the measurement terminal and the sheet so that air does not leak from the gap, and the measurement is performed using a dedicated jig as shown in Fig. 1(A) to (C). The jig shown in the figure has a jig 601 and a jig 602. A rubber packing 603 is placed between the jig 601 and the jig 602, and the sheet 100 to be measured is placed between the rubber packing 603 and the jig 601. The jig 601 has an air intake port 601A in the center. The intake port 601A has the same diameter as the measurement terminal and is a through hole that extends from the upper surface to the lower surface of the jig 601. The jig 602 has an insertion port 602A for the measurement terminal in the center. The insertion opening 602A for the measurement terminal is a through hole extending from the lower surface to the upper surface of the jig 602. Using these jigs 601 and 602, the number of particles P1 that pass through the sheet 100 is measured for particles (particle diameter 1.0 μm or more) in the air at 25° C. and 50% RH. Separately, the number of particles P2 is measured without the sheet 100. From the measured numbers of particles P1 and P2, the fine particle collection rate (%) is calculated based on the following formula (S2). A higher fine particle collection rate means a higher fine particle collection performance of the mask sheet. The size of the sheet used for the measurement is 40 mm x 40 mm, and the collection rate is measured for each of 10 sheets, and the average of these measured values ​​is taken as the collection rate. Particulate collection rate (%)=100(%)×(P2-P1) / P2 (S2)

[0025] Next, a preferred embodiment of the sheet structure of the sheet for sanitary masks of the present invention will be described.

[0026] The sheet 10 for sanitary masks (hereinafter also referred to as sheet 10) shown in FIG. 2 has a nonwoven fabric 8 in which a plurality of convex portions 1 and concave portions 2 are arranged alternately in a ridge-like shape in a natural state, and a base sheet 9 having elasticity in at least one direction. The nonwoven fabric 8 has a higher tensile modulus of elasticity than the base sheet 9, and is laminated on the surface of the base sheet 9. The tensile direction of this tensile modulus of elasticity is the stretch direction of the base sheet 9. In the ridge-like nonwoven fabric 8, the direction in which the convex portions 1 and concave portions 2 are arranged alternately is preferably the stretch direction of the base sheet 9, and is preferably the longitudinal direction X of the sheet 10 for sanitary masks. A specific configuration in this regard will be described later. Here, the term "natural state" refers to a state in which the sheet for sanitary masks of the present invention is left unfolded without applying any stretching force to the sheet surface. The tensile modulus can be measured by the method described below.

[0027] Since the uneven nonwoven fabric 8 has a grooved ridge-like uneven structure, even if the base sheet 9 is stretched until the uneven shape is deformed into a straight state by tension, the uneven nonwoven fabric 8 is not stretched in the same way as the base sheet 9, and the width shrinkage of the entire sheet 10 for hygienic masks in the axial direction perpendicular to the stretching direction is suppressed.

[0028] (Method for measuring tensile modulus) The tensile modulus of elasticity of the uneven nonwoven fabric 8, the base sheet 9, and the combined sheet 10 for a sanitary mask can be calculated from a stress-strain diagram obtained by the following method. The tensile test is started in the same manner as in the above-mentioned (Method of Measuring Shrinkage Ratio), and is continued until the load reaches the breaking point at which it suddenly drops. The stress and strain are calculated using the following formulas. Stress (kPa) = tensile load (N) / axial width of test piece (mm) / thickness of test piece (mm) × 1000 (σ1) Strain (%) = Pulled distance (mm) / Gauge length (mm) (ε1) Here, the tensile modulus of elasticity is represented by the gradient of the tangent to the stress-strain curve, and is calculated from the gradient of the line connecting two points at 0.5% strain intervals. Specifically, the slope of the stress-strain curve is calculated for every 5% strain up to the breaking point. Tensile modulus (MPa) = (σ2-σ1) / (ε2-ε1) Thereafter, the tensile modulus at the peak position obtained from the tensile modulus-strain curve is regarded as the tensile modulus obtained from the stress-strain curve.

[0029] The sheet 10 for sanitary masks of this embodiment has a first side 1S on which the uneven nonwoven fabric 8 is arranged and a second side 1R on which the base sheet 9 is arranged, and in a plan view has a longitudinal direction X and a lateral direction Y perpendicular to the longitudinal direction X. On the first side 1S of the sheet 10 for sanitary masks, the convex portions 1 of the uneven nonwoven fabric 8 protrude outward in the thickness direction in a natural state.

[0030] The base sheet 9 has stretchability in the longitudinal direction X. That is, the longitudinal direction X is the aforementioned one direction in which the base sheet 9 has stretchability, and the transverse direction Y is the aforementioned axial direction. The longitudinal direction X, which exhibits elasticity, is preferably oriented in a horizontal direction from the mouth of the wearer of the sanitary mask to the left and right ears of the wearer, and the transverse direction Y is preferably oriented in a vertical direction along the midline connecting the nose, mouth, and chin of the wearer of the sanitary mask.

[0031] In the uneven nonwoven fabric 8, when the sheet 10 for sanitary masks is in its natural state, the protrusions 1 and recesses 2 each extend continuously in the short direction Y, and are arranged alternately in the long direction X. This provides the sheet 10 for sanitary masks with a ridge-like uneven structure on the first surface 1S. The convex portions 1 and the concave portions 2 are each continuously arranged in a direction perpendicular to the stretch direction of the base sheet 9. As a result, even if the base sheet 9 is stretched by tension in the longitudinal direction X until the concave-convex shape is deformed into a straight state, the concave-convex nonwoven fabric 8 is not stretched in the same way as the base sheet 9, and the above-mentioned effect of suppressing width contraction in the axial direction becomes more evident (FIGS. 3(A) and (B)). Furthermore, when the base sheet 9 is an elastic sheet 96 described below, the multiple elastic filaments 95 arranged along the longitudinal direction X are arranged at a distance in the transverse direction Y without intersecting with each other, so that even if the elastic filaments are stretched in the longitudinal direction, a force pulling adjacent elastic filaments in the transverse direction is less likely to act, further enhancing the effect of suppressing the width shrinkage in the axial direction described above. As a result, the shape of the sanitary mask sheet 10 in the short side direction Y is easily maintained, and when the sanitary mask sheet 10 is stretched due to the elasticity of the base sheet 9, the width contraction in the short side direction Y is suppressed (FIGS. 3(A) and (B)). This results in the suppressed shrinkage rate in the axial direction as described above. Furthermore, by suppressing the shrinkage rate, unintended deformation is suppressed in a sanitary mask using the sanitary mask sheet 10, the face coverage area can be properly maintained, and the adhesion between the sanitary mask and the skin can be properly maintained. In addition, the uneven nonwoven fabric 8 has an undulating structure that can be stretched in the longitudinal direction X by alternately arranging the convex portions 1 and the concave portions 2 in the longitudinal direction X (FIGS. 3(A) and (B)). Therefore, when the sheet for sanitary masks 10 stretches in the longitudinal direction due to the elasticity of the base sheet 9, the uneven nonwoven fabric 8 exhibits a behavior in which the undulations of the ridges and grooves are stretched, and no load is applied to the internal structure. This prevents the sheet for sanitary masks 10 from deforming the filter structure (e.g., a fiber network structure, a bubble structure made of polyurethane material) that realizes the above-mentioned collection rate, and the collection function itself can be maintained unchanged. In addition, in FIG. 3(A) and (B), the height of the convex portions 1 is slightly exaggerated and shown diagrammatically in order to more clearly show the change in the unevenness due to stretching.

[0032] In the uneven nonwoven fabric 8, the shape in which the protrusions 1 extend in the short direction Y is not limited to continuous as shown in Fig. 2, but may be intermittent. The direction in which the protrusions 1 extend is not limited to completely parallel to the short direction Y, but may be a direction having some angle with the short direction Y as long as the effect of suppressing the width shrinkage described above is not hindered. In this case, the intersection angle between the extension direction of the protrusions 1 and the short direction Y is 0° or more and preferably 45° or less, and more preferably 30° or less. The shape in which the protrusions 1 extend is not limited to linear, but may be curved or meandering.

[0033] Either the first surface 1S or the second surface 1R may be the surface that comes into contact with the skin in the sanitary mask. When the first surface 1S of the sheet 10 for sanitary masks from which the convex portions 1 protrude is used as the surface contacting the skin in the sanitary mask, it is preferable that the uneven nonwoven fabric 8 is disposed on the outermost layer of the sheet 10 for sanitary masks, and that the outermost layer is used as the surface facing the skin. In this case, when the sheet 10 for sanitary masks is used in a sanitary mask, the contact area between the sheet and the skin can be reduced, and friction with the skin can be reduced to provide a gentle fit. In addition, when the second surface 1R of the sheet 10 for sanitary masks is used as the surface contacting the skin in the sanitary mask, it is preferable that the base sheet 9 is disposed on the outermost layer of the sheet 10 for sanitary masks, and that the outermost layer is used as the surface facing the skin. In this case, when the sheet 10 for sanitary masks is applied to a mask, the possibility of outside air entering through gaps in the unevenness can be further reduced.

[0034] The uneven nonwoven fabric 8 preferably includes a filter nonwoven fabric A made of fibers having an average fiber diameter of 50 nm or more and 3000 nm or less. This can increase the collection efficiency. In the example shown in Figure 2, the uneven nonwoven fabric 8 is made of only the filter nonwoven fabric A.

[0035] By using the above-mentioned filter nonwoven fabric A as the uneven nonwoven fabric 8, the mesh (spacing) between the fibers in the fiber network structure can be a filter layer with extremely fine (for example, nanometer order). This allows the sheet for sanitary masks of the present invention to achieve high collection performance. For example, it is possible to more effectively collect pollen and droplets that are generally considered to have a particle size of 3 μm to 5 μm, and even particles with a smaller particle size (for example, viruses themselves). In addition, since the filter nonwoven fabric A is made of extremely fine fibers, the mesh between the fibers can be made smaller, and high collection performance can be achieved with a thinner sheet for sanitary masks. Furthermore, the thinner thickness of the sheet for sanitary masks makes it easier to breathe and highly flexible, and further improves the gentle feel and good fit to the skin surface. From this viewpoint, the average fiber diameter of the filter nonwoven fabric A is more preferably equal to or less than 2000 nm, and further preferably equal to or less than 1000 nm. In addition, the average fiber diameter of the filter nonwoven fabric A is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 200 nm or more, from the viewpoint of ensuring appropriate breathability and making it easier for the user of the sanitary mask sheet to breathe.

[0036] Filter nonwoven fabric A has a density of 0.05 g / cm 3This is preferable. This allows the sheet 10 for sanitary masks to more effectively capture pollen, droplets, and even particles smaller than these, and also improves the strength of the filter nonwoven fabric A. From this viewpoint, the density of the filter nonwoven fabric A is 0.1 g / cm 3 More preferably, 0.15 g / cm 3 The above is more preferable. The density of the filter nonwoven fabric A is set to 0.6 g / cm from the viewpoints of ensuring a suitable degree of breathability to allow the user of the sanitary mask sheet to breathe easily, reducing compression elasticity, and achieving a soft feel. 3 Less than 0.55 g / cm is preferred. 3 Less than 0.5 g / cm is more preferable. 3 The following is even more preferred:

[0037] The average fiber diameter and density of the filter nonwoven fabric A can be measured by the following method.

[0038] (Average fiber diameter of filter nonwoven fabric A) The average fiber diameter of the filter nonwoven fabric A can be measured by measuring the maximum diameter of the fiber cross section perpendicular to the fiber length direction using a scanning electron microscope (SEM). The specific procedure is as follows. Carefully peel off the sheet for the sanitary mask to confirm how many layers it has, and then select the layer with the smallest fiber diameter (the layer that functions as a filter material) as the fiber layer to be measured. From the two-dimensional image obtained by SEM observation, 500 fibers are randomly selected, excluding defects such as fiber clumps, intersections between fibers, and polymer droplets, and the length of a line drawn perpendicular to the longitudinal direction of the fiber is directly read as the fiber diameter. From the frequency distribution (histogram) of the measured fiber diameters, the median fiber diameter with a cumulative frequency of 50% of the total is obtained, and this is the average fiber diameter of the fibers that make up the fiber layer to be measured.

[0039] (Method for measuring density of nonwoven filter fabric A) The density of the filter nonwoven fabric A can be measured by the following method. Specifically, the nonwoven fabric structure is left to stand in a natural state without external force, and the nonwoven structure is cut using a single-edged blade (product number FAS-10) manufactured by Feather Safety Razor Co., Ltd. to form a cross section of the nonwoven structure. Next, the cut cross section is magnified and observed using a scanning electron microscope (model number JCM-5100) manufactured by JEOL Ltd., a microscope, etc. The magnified cross section is used as image data or a printout, and the thickness of the filter nonwoven fabric A under no load is measured. The fuzzy fibers that are inevitably present on the surface of the nonwoven structure are excluded from the measurement. The thickness of the nonwoven structure is the average value of the thicknesses in the images magnified and observed by the above-mentioned method. Note that the above "thickness of the filter nonwoven fabric A" does not mean the height of the unevenness (the apparent thickness in the thickness direction between the first surface 1S side and the second surface 1R side of the filter nonwoven fabric A), but the thickness of the fiber layer itself that follows the unevenness. The nonwoven structure that has been left in its natural state is then cut to a predetermined area (e.g., 2 cm x 2 cm), and fiber layers other than the filter nonwoven fabric A are removed. The mass of the filter nonwoven fabric A and the surface area S1 of the irregularities measured by the method described below (Method of measuring the ratio of S1 to S0) are measured, and the basis weight is calculated by dividing the mass by the area. The basis weight is then divided by the thickness to calculate the density. Note that the above-mentioned "predetermined area" to be cut means the area along the undulations of the irregularities (or the area when the irregularities are stretched flat).

[0040] From the viewpoint of increasing the above-mentioned collection rate and making the filtration performance uniform, it is preferable that the filter nonwoven fabric A has a certain basis weight or more. 2 More than 2.5 g / m is preferable. 2 More preferably, 3 g / m 2 The above is more preferable. In order to reduce the airflow resistance, reduce the stiffness by making the sheet thinner, improve the feeling of use, and reduce costs, the basis weight of the filter nonwoven fabric A is set to 15 g / m 2 Less than 10 g / m is preferable. 2 Less than 5 g / m is more preferable. 2The following is even more preferred: When the basis weight of the filter nonwoven fabric A is within this range, it is possible to stably exhibit high particle collection performance and soft touch, and also to achieve an improvement in the feeling of use due to good breathability and thinness.

[0041] (Method of measuring basis weight) The basis weight of the filter nonwoven fabric A is calculated by the above-mentioned (Method of measuring the density of the filter nonwoven fabric A).

[0042] The filter nonwoven fabric A is preferably a fiber layer produced by electrospinning (electric field spinning) (hereinafter, such filter nonwoven fabric A is also referred to as electrospun nonwoven fabric). In the electrospinning (electric field spinning) method, a solution or melt of a resin having fiber-forming ability is charged and discharged into an electric field, the discharged liquid is stretched by the electric field to form fibers, and the fibers are deposited on a collector, thereby producing the filter nonwoven fabric A. In this manufacturing method, the discharged resin solution or melt is stretched by the Coulomb force in an electric field, thereby obtaining ultrafine fibers on the order of nanometers that cannot be achieved by conventional mechanical stretching using air, etc. In contrast, conventional nonwoven fabric manufacturing methods, such as the meltblown method, form fibers by stretching the discharged molten resin by blowing high-temperature gas onto it, and the limit is fibers on the order of micrometers. Therefore, the above-mentioned fiber layer becomes an assembly layer of extremely fine fibers on the nanometer order by the electrospinning method, which is an order of magnitude greater than that obtainable by the conventional meltblowing method.

[0043] In addition, such an electrospinning fiber layer has a density necessary for high collection of the above-mentioned particles, and yet has a moderately suppressed density and is highly flexible compared to nonwoven fabrics manufactured by the meltblown method (hereinafter also referred to as meltblown nonwoven fabrics). This is due to the difference in the manufacturing methods of the two. In the electrospinning method, ultrafine fibers with a diameter of several nanometers can be obtained by Coulomb force, so long fibers are formed without breaking the fibers, compared to spinning by blowing high-temperature gas in the meltblown method. In addition, the solution discharged by the Coulomb force in the electric field is stretched and the solvent evaporates instantly, and the raw material is solidified to form nanofibers. Therefore, in the electrospinning fiber layer, the long fibers are often not fused together, and since the fibers are formed by entanglement with each other, the movement of the fibers is not hindered and high flexibility is obtained. In contrast, in nonwoven fabrics manufactured by the meltblown method (hereinafter also referred to as meltblown nonwoven fabrics), the fibers are cut by blowing high-temperature gas, and the fibers are layered and fused while still melted. Therefore, the meltblown nonwoven fabric has less bulk in the thickness direction than the electrospun fiber layer, and the movement of the fibers is hindered, resulting in a relatively high rigidity. Thus, the electrospun fiber layer has a fiber state different from that of a meltblown nonwoven fabric, and is relatively bulky and flexible. The sheet for sanitary masks 10 of this embodiment, which contains such a filter nonwoven fabric A as the uneven nonwoven fabric 8, maintains the high collection ability described above while providing an even softer feel to the skin.

[0044] By having the rugged nonwoven fabric 8 made of the filter nonwoven fabric A in the sheet 10 for sanitary masks of this embodiment, the effective area of ​​the filtering function is increased, and the above-mentioned collection rate can be further increased. At the same time, the filter nonwoven fabric A is a very soft layer made of ultrafine fibers as described above, and by forming it into the uneven nonwoven fabric 8, it becomes bulky while remaining soft, enhancing cushioning properties. In addition, by forming the filter nonwoven fabric A into the uneven nonwoven fabric 8, it becomes more resistant to pressure and pulling, and is more likely to retain its bulk. As a result, the sheet 10 for sanitary masks has the high collection ability described above, and at the same time, it is also more soft to the touch. In addition, the uneven structure of the uneven nonwoven fabric 8 increases the effective area through which air passes, making it possible to reduce air pressure loss. Conventionally, when the collection rate is improved by narrowing the average fiber diameter of the sheet or increasing the density, the air permeability through the sheet tends to decrease, and it is difficult to simultaneously improve both performances. In contrast, the sheet 10 for sanitary masks of this embodiment uses the uneven nonwoven fabric 8 as the filter nonwoven fabric A, so that it is possible to simultaneously improve both the collection rate and breathability. As a result, the sheet 10 for sanitary masks of this embodiment can improve the filtering function against particles and the like in the sanitary mask, and at the same time, improve the ease of breathing. Furthermore, when the sheet 10 for sanitary masks is applied to a sanitary mask and worn on the face, it comes into contact with the skin mainly only at the protruding parts 1 of the uneven nonwoven fabric 8, reducing the contact area. This reduces friction with the skin, improving the comfort of wearing the sanitary mask.

[0045] In the sheet 10 for sanitary masks of this embodiment, when the uneven nonwoven fabric 8 is stretched in a direction (longitudinal direction X) perpendicular to the extension direction (transverse direction Y) of the protrusions 1, it is preferable that the uneven nonwoven fabric 8 has an inflection point P at which the tensile modulus changes by 100% or more when the protrusions 1 are stretched and a tensile load is applied to the uneven nonwoven fabric 8. As shown in FIG. 4, this inflection point P is a point where the slope of the stress (σ) strain (ε) curve changes suddenly, and can be defined as a point where the stress of the stretchable base sheet 9 changes from a region TR where the stress of the uneven nonwoven fabric 8 is dominant to a region TF where the stress of the uneven nonwoven fabric 8 is dominant. The inflection point P is defined as a sudden change of tensile modulus of elasticity of 100% or more. Note that the stress (σ) strain (ε) curve shown in FIG. 4 is an example for understanding the inflection point P, and is not limited thereto. In this embodiment, it may widely include various stretch behaviors in which the stress rises suddenly around the inflection point P while satisfying the above tensile modulus requirements. In addition, the units of the stress axis and the strain axis are arbitrary units. The slope (tensile modulus) obtained from the stress-strain curve of a typical stretchable sheet is highest immediately after tensioning begins, and then the slope becomes gentler as plastic deformation occurs. In contrast, the sheet 10 for sanitary masks of this embodiment has the structure described above, and the tensile modulus changes sharply at the inflection point P. Therefore, it is preferable that the tensile modulus has two or more peaks in the tensile modulus in the tensile modulus-strain curve.

[0046] (Method for measuring the rate of change in tensile modulus of elasticity) When there is an inflection point P where the tensile modulus changes, the stress-strain curve before the inflection point P is reached and the stress-strain curve after the inflection point P are separated and the tensile modulus is calculated by the above-mentioned method for each. Here, the rate of change in the tensile modulus is calculated from the maximum value E1 of the tensile modulus obtained from the stress-strain curve before the inflection point P is reached and the maximum value E2 of the tensile modulus obtained from the stress-strain curve after the inflection point P. Change in tensile modulus (%) = E2 / E1 x 100

[0047] The rate of change in tensile elastic modulus of the sheet 10 for sanitary masks of this embodiment is preferably 200% or more. The tensile direction here is the direction (longitudinal direction X) perpendicular to the extension direction (transverse direction Y) of the convex portions 1 of the uneven nonwoven fabric 8. When the rate of change in the tensile modulus is 200% or more, the change in the tensile modulus becomes clear, and the notification function for preventing excessive elongation works predominantly. The rate of change in the tensile modulus is more preferably 500% or more, and further preferably 1000% or more, from the viewpoint of clearly indicating the change in the tensile modulus.

[0048] Such a sudden change in the tensile modulus allows the user to accurately recognize the range of use, for example, by allowing the user to feel the limit of elongation of the base sheet 9, or the limit at which the uneven structure of the uneven nonwoven fabric 8 is stretched and the fiber structure of the uneven nonwoven fabric 8 breaks. In other words, the sheet 10 for sanitary masks has a notification function that prevents excessive elongation, and this can encourage the user to use the sheet 10 appropriately to properly achieve the above-mentioned collection rate.

[0049] In the sheet 10 for sanitary masks of the present invention, the ratio EB / EA of the tensile modulus EB of the uneven nonwoven fabric 8 to the tensile modulus EA of the base sheet 9 is preferably 2 or more. The tensile direction here is the direction (longitudinal direction X) perpendicular to the extension direction (transverse direction Y) of the protrusions 1 of the uneven nonwoven fabric 8. When the ratio EB / EA is 2 or more, the change in the tensile modulus becomes clear, and the notification function for preventing excessive elongation becomes dominant. The ratio EB / EA is more preferably 5 or more, and further preferably 10 or more, from the viewpoint of clearly indicating a change in the tensile modulus of elasticity.

[0050] In the sheet 10 for sanitary masks of this embodiment, the distance between adjacent protrusions 1, 1 (protrusion distance) is preferably 1 mm or more and 6 mm or less in the natural state. This protrusion distance means the distance between the centers of adjacent protrusions 13 when viewed in a plan view of the sheet 10 for sanitary masks in the natural state, and the center of the protrusions 1 means the central point of the top of the protrusions 1. By setting the interval between the protrusions to 1 mm or more, the shape stability of the protrusions 1 is improved. As a result, even when the sheet 10 for sanitary masks is used repeatedly or for a long period of time, the sheet 10 can maintain both the high particle collection ability and the soft feel for a longer period of time. By making the projection interval 6 mm or less, the surface area formed by the projections and recesses can be efficiently increased, the ventilation resistance can be effectively reduced, and breathing becomes easier. In addition, the contact area with the skin can be reduced, and friction with the skin can be significantly reduced, and the comfort of wearing the sheet 10 for sanitary masks and the sanitary masks using the same can be further improved. From the above viewpoint, the projection interval is more preferably 1.5 mm or more, and further preferably 2 mm or more. From the above viewpoint, the projection interval is more preferably 5 mm or less, and further preferably 4 mm or less.

[0051] Next, a preferred embodiment of the structure of the uneven nonwoven fabric 8 will be described.

[0052] As shown in FIG. 2, the uneven nonwoven fabric 8 preferably has a plurality of protrusions 3 protruding outward in the thickness direction in a natural state and a recessed portion 4 sandwiched between the plurality of protrusions 3 on the second surface 1R, which is the surface opposite to the first surface 1S. It is preferable that the protrusions 3 and the recessed portions 4 extend in the short direction Y on this second surface 1R as well, and are arranged alternately in the longitudinal direction X. In this case, the recessed portions 4 on the second surface 1R correspond to the protrusions 1 on the first surface 1S, and the protrusions 1 and the recessed portions 4 are in a front-back relationship. The protrusions 3 on the second surface 1R correspond to the recessed portions 2 on the first surface 1S, and the recessed portions 2 and the protrusions 3 are in a front-back relationship. In this arrangement, the protrusions 1 on the first surface 1S and the protrusions 3 on the second surface 1R are each hollow inside. As a result, the uneven nonwoven fabric 8 has a corrugated shape like galvanized iron with uneven surfaces on both sides.

[0053] In the uneven nonwoven fabric 8, at least one of the protrusions 1 on the first surface 1S and the protrusions 3 on the second surface 1R is hollow, which has the advantage that when an external force is applied in the thickness direction, the protrusions exhibit a buffering effect against the external force, providing a high cushioning feeling. In addition, when the protrusions receive an external force from the side, they easily deform flexibly, which has the advantage of reducing friction with the skin. Another advantage is that the increase in airflow resistance can be effectively suppressed compared to when the inside of the protrusions 1 is solid.

[0054] The above-mentioned "hollow" refers to a space inside the protrusions 1 and 3 that is not substantially filled with fibers, specifically, a space having a fiber density of 5 fibers / mm 2 The term "solid" means that the inside of the second surface 1R side of the protrusion 1 is substantially filled with fibers, and specifically, the fiber density is less than 5 fibers / mm 2 This means that it is more than or equal to this.

[0055] (How to check if it is hollow or not) The uneven nonwoven fabric 8 is cut in the thickness direction so as to pass through the apex of the projection to be measured. The cut surface is magnified and observed using an SEM, and the number of cut fiber cross sections within a certain area of ​​the cut surface is counted. The magnification for magnification observation is adjusted to a magnification (150x or more and 500x or less) that allows the measurement of approximately 30 to 60 fiber cross sections. Next, 2 This is converted into the number of fiber cross sections per unit, and the fiber density (fibers / mm 2 The measurement results at the three locations are averaged to determine the fiber density of the sample. Note that various types of devices can be used as the SEM. For example, JCM-5100 (product name) manufactured by JEOL Ltd. can be used.

[0056] The uneven structure of the uneven nonwoven fabric 8 constituting the sheet for sanitary masks 10 is not limited to the above and may take various forms as long as it does not impair the above-mentioned effects of the sheet for sanitary masks of the present invention. For example, as a modified example of the uneven nonwoven fabric 8, the second surface 1R may be flat. Also, the protrusions 1 may be solid.

[0057] In the sheet for sanitary masks 10, the height of the convex portions 1 on the first surface 1S in a natural state is preferably as follows: The "height of the convex portions 1" referred to here means the height difference E in the thickness direction between the top of the convex portion 1 and the surface on the first surface 1S side of the bottom of the recessed portion 2 adjacent to the convex portion 1, as shown in Fig. 5(A), when the sheet for sanitary masks 10 is placed on a horizontal surface with the second surface 1R facing down and viewed from the side, as shown in Fig. 5(A). The thickness direction here means the vertical direction with respect to the horizontal surface on which the sheet for sanitary masks 10 is placed. The height of the protrusions 1 on the first surface 1S in the natural state is preferably 1 mm or more, more preferably 1.5 mm or more, and even more preferably 2 mm or more. Such a height difference is much larger than that caused by normal embossing. This increases the cushioning properties of the sheet 10 for sanitary masks at the protrusions 1, and further improves the soft feel. Furthermore, the height of the protrusions 1 on the first surface 1S in the natural state is preferably 4 mm or less, more preferably 3.5 mm or less, and even more preferably 3 mm or less, thereby improving the shape stability of the protrusions 1. As a result, even when the sheet 10 for sanitary masks is used repeatedly or for a long period of time, it is possible to achieve a high degree of particle collection as described above, while lowering the contraction rate in the transverse direction Y perpendicular to the longitudinal direction X when the sheet is stretched.

[0058] In the case where the second surface 1R of the uneven nonwoven fabric 8 has an uneven structure, it is preferable that the above-mentioned requirement for the height of the protrusions 1 on the first surface 1S is also satisfied on the second surface 1R. By satisfying the requirement for the height of the protrusions 1 on both the first surface 1S and the second surface 1R, the above-mentioned effect is further enhanced.

[0059] (Method of measuring height difference E in the thickness direction between the top of protrusion 1 and the surface on the first surface 1S side at the bottom of recess 2 adjacent to protrusion 1) The height difference E can be measured in the following manner. First, as shown in Fig. 5(A), T1 is measured as the thickness between the front and back surfaces of the sheet for sanitary masks 10. This refers to the vertical height from the position of the horizontal plane to the top of the protrusions 1 when the second surface 1R of the sheet for sanitary masks 10 is placed on a horizontal plane. Next, T2 is measured as the height of the surface on the first surface 1S side at the bottom of the recess 2. This refers to the vertical height from the position of the above-mentioned horizontal plane to the surface on the first surface 1S side at the bottom of the recess 2. Based on the above measurements, the elevation difference E can be calculated as T1 - T2. As a specific measurement method, a cross section in the thickness direction of the sheet for sanitary masks 10 is magnified with a microscope, and the height difference E, in other words, the height E of the hollow space, is directly measured by image processing. Alternatively, a laser displacement meter may be scanned from the upper surface of the sheet for masks 10 to measure T1 and T2, and the height difference E may be calculated. Note that even when a protective sheet 81 described below is laminated in the textured nonwoven fabric 8 (see FIG. 5(B)), the definition of the height difference E does not change, and the measurement may be performed in a similar manner.

[0060] The thickness (T1) between the front and back surfaces of the sheet 10 for sanitary masks is preferably 1 mm or more, more preferably 1.5 mm or more, and even more preferably 2 mm or more, from the viewpoints of effectively reducing air resistance to facilitate breathing, ensuring cushioning by the uneven nonwoven fabric 8, and maintaining a soft feel against the skin. In addition, the thickness (T1) between the front and back surfaces of the sheet 10 for sanitary masks is preferably 6 mm or less, more preferably 5 mm or less, and even more preferably 4 mm or less, from the viewpoint of improving the handleability and appearance of the sheet 10 for sanitary masks.

[0061] In addition, in the natural state of the sheet 10 for sanitary masks, the area of ​​the constitutive uneven nonwoven fabric 8 when viewed in plan from the first surface 1S side is preferably as follows. That is, when the sheet 10 is left in a natural state and the first surface 1S side is projected onto a plane, the unit area is defined as S0, and the surface area of ​​the irregularities in the unit area S0 is defined as S1. At this time, it is preferable that the value of S1 is larger than the value of S0 due to the first surface 1S of the irregular nonwoven fabric 8 having an irregular structure. In other words, by having the first surface 1S side of the sheet 10 have an irregular structure, the effective area through which air passes is increased compared to when the first surface 1S side of the sheet 10 does not have an irregular structure. By increasing the effective area, the filtering area for the above-mentioned particles and the like is increased, making it easier to increase the above-mentioned collection rate. From this viewpoint, in the natural state of the sheet 10, it is preferable that the ratio (S1 / S0) of the surface area S1 of the irregularities per unit area S0 in a planar projection view exceeds 1, more preferably 1.3 or more, and even more preferably 1.5 or more. Furthermore, from the viewpoint of the shape stability of the convex portions, in the natural state of the sheet 10, it is preferable that the ratio of the surface area S1 of the concaves and convexes per unit area S0 in a planar projection view is 3 or less, more preferably 2.8 or less, and even more preferably 2.5 or less.

[0062] In the uneven nonwoven fabric 8, when the second side 1R has an uneven structure, it is preferable that the requirement for the ratio of the surface area S1 of the unevenness to unit area S0 on the first side 1S is also satisfied on the second side 1R. The above-mentioned effect is further enhanced by satisfying the requirement for the ratio of the surface area S1 of the unevenness to unit area S0 on both the first side 1S and the second side 1R.

[0063] (Method of measuring the ratio of S1 to S0) The uneven nonwoven fabric 8 constituting the sheet 10 for sanitary masks is placed in its natural state and an arbitrary area S0' (for example, 10 cm x 10 cm = 100 cm 2 The cut out uneven nonwoven fabric 8 is flattened without any wrinkles and its area S1' is measured, and the ratio of S1 to S0 is calculated using the following formula. S1 / S0=S1' / S0' However, depending on the bonding state between the embossed nonwoven fabric 8 and the base sheet 9, the embossed nonwoven fabric 8 may undergo plastic deformation during delamination. In such a case, as shown in Fig. 6(A), the base sheet 9 may be cut with a cutter or the like at the convex portion 1 where the embossed nonwoven fabric 8 and the base sheet 9 are separated, dividing the base sheet 9 into individual independent pieces. In this way, the embossed nonwoven fabric 8 can be spread out flat (Fig. 6(B)), making it possible to measure the S1'. When the uneven nonwoven fabric 8 is a laminate of a filter nonwoven fabric A and a protective sheet 81 as described below, these can be treated as an integrated unit and measured in the same manner as above.

[0064] In addition, the uneven nonwoven fabric 8 is not limited to being made of only the filter nonwoven fabric A, but may be a laminate of the filter nonwoven fabric A and other sheets. The other sheets may be one sheet or two or more sheets. The other sheets may be made of various materials, and are preferably nonwoven fabrics from the viewpoint of texture. As the nonwoven fabric, various materials can be used as described above. Among them, spunbond nonwoven fabrics and needle punch nonwoven fabrics are preferred from the viewpoint of ensuring the strength and improving the cushioning of the sheet for sanitary masks of the present invention. The other sheet may be disposed on either the first surface 1S or the second surface 1R of the uneven nonwoven fabric 8 constituting the sheet 10 for a sanitary mask. A specific example of such a concave-convex nonwoven fabric 8 is shown in FIG. 5(B). In this specific example, the uneven nonwoven fabric 8 has a configuration in which the filtering nonwoven fabric A is disposed on the second surface 1R, and a protective sheet 81 is disposed on the first surface 1S as the other sheet. The filtering nonwoven fabric A and the protective sheet 81 are laminated together to form an uneven shape.

[0065] In the uneven nonwoven fabric 8 shown in Figure 5 (B), it is preferable that the uneven shape of the protective sheet 81 is complementary to the uneven shape of the filter nonwoven fabric A, and it is preferable that the protective sheet 81 has a shape that follows the shape of the filter nonwoven fabric A. It is preferable that the protective sheet 81 and the filtering nonwoven fabric A are in close contact with each other with no gaps therebetween. The protective sheet 81 and the filter nonwoven fabric A are preferably bonded by entanglement of fibers or by an adhesive. From the viewpoint of not deteriorating the texture of the sanitary mask sheet 10, the protective sheet 81 and the filter nonwoven fabric A are preferably bonded by entanglement of fibers. The protrusions in the protective sheet 81 are preferably located at the same positions as the protrusions in the filtering nonwoven fabric A. Similarly, the recesses in the protective sheet 81 are preferably located at the same positions as the recesses in the filtering nonwoven fabric A.

[0066] In the uneven nonwoven fabric 8 shown in Fig. 5(B), the presence of the protective sheet 81 can prevent the direct application of external force to the filter nonwoven fabric A. This can prevent the filter nonwoven fabric A from being damaged or otherwise losing performance. This is particularly effective when the first surface 1S of the uneven filter nonwoven fabric 8 is the skin contact surface of the sanitary mask.

[0067] Regarding lamination of the filter nonwoven fabric A and the protective sheet 81, it is preferable from the viewpoint of productivity to deposit spun fibers on one side of a previously manufactured protective sheet 81 to obtain the filter nonwoven fabric A. For example, the uneven nonwoven fabric 8 can be produced by depositing fibers spun by an electrospinning method on one side of a roll of a previously manufactured spunbond nonwoven fabric. This allows the protective sheet 81 and the filter nonwoven fabric A to be bonded by entanglement of the fibers.

[0068] In the uneven nonwoven fabric 8, it is preferable that the requirements for the height (T1-T2) of the protrusions 1, the spacing between the protrusions 1, and the ratio (S1 / S0) of the surface area S1 of the unevenness per unit area S0 in a planar projection view are satisfied as a laminate of the filter nonwoven fabric A and the protective sheet 81.

[0069] In the uneven nonwoven fabric 8, the protective sheet 81 not only protects the filter nonwoven fabric A, but also complements the filter nonwoven fabric A's ability to collect particles and the like. That is, the protective sheet 81 has relatively thick fibers as a protective layer for the filter nonwoven fabric A, and collects relatively large particles. Therefore, the filter nonwoven fabric A can specialize in collecting fine particles with a smaller particle size, and as a result, the uneven nonwoven fabric 8 is expected to have an extended life as a filter material. In this way, from the viewpoint of sharing the collection function between the protective sheet 81 and the filter nonwoven fabric A, it is preferable that the collection rate of the protective sheet 81 is lower than that of the filter nonwoven fabric A, and that there is a certain degree of difference between the two collection rates.

[0070] The uneven nonwoven fabric 8 is preferably joined to the base sheet 9 at the recesses 2. More specifically, the surface of the first surface 1S on the second surface 1R side of the recesses 2 is preferably joined to the base sheet 9. This joining is preferably formed along the extension direction of the recesses 2. Various methods can be used for this bonding, such as fusion bonding by embossing or adhesion by adhesive. As for embossing, various methods commonly used for this type of article can be used, such as thermal embossing and ultrasonic embossing. Furthermore, the embossing is preferably point embossing at the contact area between the uneven nonwoven fabric 8 and the base sheet 9. Such bonding gives the protrusions 1 an arch structure, making them resistant to compressive loads. That is, the compressive load applied to the first surface 1S is propagated from the top of the protrusions 1 to the base, and is dispersed and absorbed at the bonding points. In addition, the bonding points are located in the recesses 2 recessed between the protrusions 1, making them less likely to come into contact with the skin. This also limits the bonding area, thereby reducing the rigidity of the uneven nonwoven fabric 8 and maintaining the cushioning properties of the uneven nonwoven fabric 8. In addition, by bonding the uneven nonwoven fabric 8 to the base sheet 9 along the extension direction of the recesses 2, the shape of the recesses 1 in the short side direction Y is more easily maintained when stretched in the longitudinal direction X. Accordingly, the shape of the protrusions 1 in the short side direction Y is also more easily maintained. As a result, the pillar-like action of the protrusions 1 and the recesses 2 works more strongly, making it even more difficult for the width of the sheet 10 for sanitary masks in the short side direction Y to shrink.

[0071] In order to make the above-mentioned action more effective, it is preferable to dispose a plurality of joints 21 in a plurality of intermittent rows along the extending direction of the recess 2 (short-side direction Y) as shown in FIG. The shape of the joint 21 is typically circular. However, the shape of the joint 21 is not limited to this, and may be a shape other than a circle, for example, a polygon such as a triangle, a rectangle, or a hexagon, or other shape. The joint 21 may have a length along the extending direction of the recess 2 (short-side direction Y). By arranging the joints 21 intermittently in this manner along the short direction Y, even when the sheet 10 for sanitary masks is stretched in the longitudinal direction X, shrinkage in the short direction Y is suppressed, and the shrinkage rate of the sheet 20 for sanitary masks in the short direction Y is within 10%. This allows the sanitary mask made of the sheet 10 to reliably cover a wide area along the midline connecting the wearer's nose, mouth, and chin and the surrounding areas.

[0072] When focusing on one bonding point row, the distance between adjacent bonding points 21 along the direction in which the recesses 2 are arranged may be the same or different. Furthermore, when focusing on one bonding point row, the shapes of the individual bonding points 21 constituting the bonding point row may all be the same, or the bonding points may include bonding portions of two or more different shapes.

[0073] Next, a preferred embodiment of the structure of the base sheet 9 will be described.

[0074] The basis weight of the base sheet 9 is preferably greater than the basis weight of the filtering nonwoven fabric A, in order to impart greater strength to the base sheet 9. The basis weight of the base sheet 9 is set to 5 g / m from the viewpoint of improving the strength of the base sheet 9 and ensuring the shape retention of the sheet for a sanitary mask. 2 More than 10 g / m is preferable. 2 More preferably, 15 g / m 2 The above is more preferable. The basis weight of the base sheet 9 is set to 55 g / m from the viewpoint of reducing the rigidity and airflow resistance of the base sheet 9 and improving the wearing comfort of the sheet 10 for sanitary masks and the sanitary masks using the same. 2 Less than 50 g / m is preferable. 2 Less than 45 g / m is more preferable. 2 The following is even more preferred:

[0075] Examples of the base sheet 9 that has elasticity include a nonwoven fabric made of elastic fibers, a nonwoven fabric made of elastic fibers and non-elastic fibers, and a composite nonwoven fabric made of a non-elastic nonwoven fabric and an elastic body (e.g., elastic filaments).

[0076] A particularly preferred stretch sheet for use as the base sheet 9 is a nonwoven fabric containing elastic filaments, and a particularly preferred stretch sheet is a composite nonwoven fabric of a non-stretchable nonwoven fabric and an elastic body (e.g., elastic filaments). The stretch sheet may be a blend of elastic filaments or stretchable and non-stretchable fibers. In either case, the stretch sheet is preferably subjected to a stretching process described below. In particular, as shown in FIG. 8, a stretchable sheet 96 made of a composite nonwoven fabric in which a pair of inelastic nonwoven fabrics 94, 94 are joined by fusion of elastic filaments 95 is preferred.

[0077] The elastic filaments 95 are preferably bonded to the nonwoven fabrics 94, 94 containing inelastic fibers in a substantially unstretched state. Also, a plurality of elastic filaments 95 are preferably bonded to a pair of nonwoven fabrics 94, 94. It is preferable that the multiple elastic filaments 95 are arranged so as to extend in the longitudinal direction X without crossing each other, so that the stretchable sheet 96 can stretch in the longitudinal direction X. In addition, the elastic filaments 95 arranged along the longitudinal direction X are arranged at intervals in the transverse direction Y without crossing each other, so that the width of the nonwoven fabric 94 is suppressed even if the elastic filaments 95 are stretched. As a result, the base sheet 9 made of the stretchable sheet 96 and the sheet 10 for sanitary masks comprising the same have the advantage that, when stretched in the direction in which the elastic filaments 95 extend, width shrinkage in the transverse direction Y perpendicular to the direction does not easily occur. To suppress this width shrinkage, it is advantageous for the aforementioned joining point row to be arranged in the transverse direction Y. The elastic filaments 95 may extend linearly or meanderingly as long as they do not intersect with each other. In addition, the elastic filaments 95 are preferably arranged at intervals in the transverse direction Y perpendicular to the longitudinal direction X.

[0078] It is preferable that the one or more nonwoven fabrics 94 constituting the stretch sheet 96 are all stretchable. The one or more nonwoven fabrics 94 typically comprise substantially inelastic fibers and are substantially inelastic. The nonwoven fabric 94 is preferably stretchable in the same direction as the longitudinal direction X in which the elastic filaments 95 extend. Here, "stretchable" includes (i) the case where the constituent fibers of the nonwoven fabric 94 themselves stretch, and (ii) the case where the constituent fibers themselves do not stretch, but the nonwoven fabric as a whole stretches as a result of fibers that were bonded at intersections separating from each other, the three-dimensional structure formed by multiple fibers due to bonding between fibers, etc., changing structurally, constituent fibers breaking, or slack fibers being stretched. Each nonwoven fabric 94 may already be stretchable in the state of a raw roll before being joined to the elastic filament 95. Although the nonwoven fabric 94 is not stretchable in the state of a raw roll before being joined to the elastic filament 95, it may be stretchable by being processed so as to be stretchable after being joined to the elastic filament 95. Specific methods for making the nonwoven fabric 94 stretchable include heat treatment, stretching between rolls, stretching by biting with teeth or gears, and tensile stretching by a tenter. From the viewpoint of improving the transportability of the nonwoven fabric 94 when the elastic filament 95 is fused to the nonwoven fabric 20, it is preferable that the nonwoven fabric 94 is not stretchable in the state of the raw roll.

[0079] Each of the plurality of elastic filaments 95 is preferably substantially continuous over the entire length of the stretch sheet 96. Each of the elastic filaments 95 typically preferably contains an elastic resin.

[0080] The elastic filament 95 may be a synthetic or natural rubber filament. It may be obtained by dry spinning (melt spinning) or wet spinning. It is preferable that the elastic filament 95 is obtained by direct melt spinning without first winding it. The elastic filaments 95 are preferably obtained by drawing undrawn yarn. The elastic filaments 95 are preferably formed by stretching an elastic resin in a molten or softened state, so that the elastic filaments 95 can be appropriately bonded to the nonwoven fabric 94 in a non-stretched state. Specific examples of the drawing operation include (a) melt-spinning the resin that is the raw material of the elastic filament 95 to obtain an undrawn yarn, and then heating the undrawn elastic filament again to draw it at a temperature equal to or higher than the softening temperature (glass transition temperature Tg of the hard segment), and (b) directly drawing the molten fiber obtained by melt-spinning the resin that is the raw material of the elastic filament 95. It is particularly preferable that the elastic filament 95 be obtained by directly drawing the molten fiber obtained by melt spinning.

[0081] Each elastic filament 95 is preferably bonded to the nonwoven fabric 94 along its entire length. The phrase "bonded over the entire length" does not require that all fibers (constituent fibers of the nonwoven fabric 94) in contact with the elastic filament 95 are bonded to the elastic filament 94. In other words, it means that the elastic filament 95 and the constituent fibers of the nonwoven fabric 94 are bonded together in such a manner that there are no intentionally formed non-bonded portions. The elastic filament 95 and the nonwoven fabric 94 may be bonded, for example, by welding or by adhesion with an adhesive. It is also preferable to weld the elastic filament 95 obtained by melt spinning to the nonwoven fabric 94 before solidification. In this case, before bonding the nonwoven fabric 94 and the elastic filament 95, an adhesive can be applied as an auxiliary bonding means. After bonding each nonwoven fabric 94 and the elastic filament 95, a heat treatment (steam jet, heat embossing) or mechanical entanglement (needle punch, spun lace) can also be performed as an auxiliary bonding means. The bonding between the nonwoven fabric 94 and the elastic filaments 95 is preferably achieved simply by the elastic filaments 95 in a molten or softened state solidifying when in contact with the nonwoven fabric 94, i.e., without using any adhesive, in order to improve the flexibility of the elastic sheet 96.

[0082] The stretchability of the stretch sheet 96 is manifested by the elasticity of the elastic filaments 95. When the stretch sheet 96 is stretched in the same direction as the extension direction of the elastic filaments 95, the elastic filaments 95 and the nonwoven fabric 94 are stretched. When the stretch sheet 96 is released from the stretching, the elastic filaments 95 contract, and as the contraction occurs, the nonwoven fabric 94 returns to its state before being stretched.

[0083] Such a stretchable sheet 96 can typically be produced by the method described in paragraphs

[0055] to

[0085] of JP 2008-179128 A. Specifically, a molten elastic filament 95 is bonded in an unstretched state to a pair of inelastic nonwoven fabrics 94, 94 to produce an unstretched composite material. The composite material is passed between a pair of grooved rolls arranged opposite each other in a state capable of meshing with each other, thereby performing a stretching process to exhibit stretchability, and a stretchable sheet 96 is obtained.

[0084] As the stretchable sheet 96 which has been subjected to the aforementioned biting and stretching using teeth and grooves or the like, the one shown in FIG. 9 is preferable. The stretchable sheet 96 shown in Fig. 9 has a biting extension portion 94T along the short side direction Y of the non-stretchable nonwoven fabric 94, and the biting extension portions 94T are arranged at equal intervals in the longitudinal direction X. The tooth groove processed portion 94T weakens the entanglement of the fibers of the nonwoven fabric 94 by biting extension, and becomes a portion that is easy to stretch. That is, in the tooth groove processed portion 94T, the stretchability of the elastic filaments 95 is increased, while at the same time, the effect of the elastic filaments 95 on the stretchable nonwoven fabric 94 is reduced. Therefore, when the stretchable sheet 96 stretches in the longitudinal direction X, the width contraction in the short side direction Y becomes even less likely to occur.

[0085] Another specific example of the base sheet 9 having stretchability in at least one direction is shown in FIG. FIG. 10 shows a porous sheet 97 made of a polyurethane material that exhibits uniform elasticity not only in one direction but in all directions in the sheet plane. As shown in FIG. 10, this porous sheet 97 has support members 98 arranged in the Y direction to prevent contraction in the short-side direction Y. It is preferable to arrange a plurality of support members 98 intermittently in the longitudinal direction X, and more preferably to arrange them at equal intervals. As the support member 98, various materials can be used as long as they prevent the elastic sheet 91 from contracting in the short-side direction Y when the sheet 10 is pulled in the longitudinal direction X. Among them, it is preferable that the support member has a relatively high rigidity and a certain degree of flexibility. The shape is preferably a rod-like object. For example, it can be one having axial rigidity. Examples of such materials include flexible thread- or ribbon-like metals, plastics, and the like.

[0086] Next, a preferred embodiment of a method for producing the sheet for sanitary masks 10 of the present embodiment will be described. As shown in Figs. 11(A) to (C), the method for producing a sheet for sanitary masks of the present embodiment preferably includes the following steps (I) to (III) (hereinafter also referred to as step (I), step (II), and step (III)). First, (I) a process is performed in which the base sheet 9 is stretched along the stretch direction X to 40% or more and 99% or less of its breaking elongation rate, and a flat raw material nonwoven fabric 800 before the unevenness is formed into the uneven nonwoven fabric is laminated on the base sheet 9 (FIG. 11(A)). At this time, by elongating the uneven surface area of ​​the uneven nonwoven fabric 8 to 40% or more and 99% or less of the breaking elongation rate, it is possible to increase the uneven surface area of ​​the uneven nonwoven fabric 8 without breaking the base sheet 9. From the viewpoint of increasing the uneven surface area of ​​the uneven nonwoven fabric 8 and decreasing the airflow resistance, a step of laminating the flat raw nonwoven fabric 800 before the unevenness is formed on the uneven nonwoven fabric 8 is performed in a state in which the uneven nonwoven fabric 8 is elongated to preferably 50% or more, more preferably 60% or more of the breaking elongation rate. Also, from the viewpoint of maintaining the fiber structure of the base nonwoven fabric, a step of laminating the flat raw nonwoven fabric 800 before the unevenness is formed on the uneven nonwoven fabric 8 is performed in a state in which the uneven nonwoven fabric 8 is elongated to preferably 95% or less, more preferably 90% or less of the breaking elongation rate.

[0087] <Method of measuring breaking elongation> The above breaking elongation percentage can be calculated by the equation: elongation (%)=100×(LB−L0) / L0, where L0 is the sample length before the test and LB is the sample length at break. Specifically, the measurement is performed in accordance with the general nonwoven fabric testing method JIS L1913. The measurement conditions are as follows. Measurement sample grip length: 40mm Crosshead speed: 100mm / min (Distortion rate: 8.3×10 -3 / sec) Sample width: 25mm Temperature: 23℃, relative humidity: 50%Rh If the gripping length of the measurement sample cannot be 40 mm, make it as close to 40 mm as possible. At this time, the crosshead speed (CHSP) should be set to the same strain rate. Also, if the sample width cannot be 25 mm, make it as close to 25 mm as possible.

[0088] Next, (II) a process is performed in which joints that integrate the base sheet 9 and raw nonwoven fabric 800 are formed in the recessed areas 802 of raw nonwoven fabric 800 along direction Y perpendicular to the stretch direction X (Figure 11(B)).

[0089] Next, (III) a process is performed in which the base sheet 9 is returned to its natural state to shrink the raw nonwoven fabric 800, and an uneven nonwoven fabric 8 in which convex portions 1 and concave portions 2 are alternately formed in a ridge-like pattern is formed on the surface of the base sheet 9 (Figure 11(C)).

[0090] This makes it possible to suitably manufacture the sheet 10 for sanitary masks of this embodiment, in which a rugged nonwoven fabric 8 having a tensile modulus higher than that of the base sheet 9 and in which convex portions and concave portions are arranged in a ridge-like pattern is laminated on the surface of a base sheet 9 that is stretchable in at least one direction.

[0091] The sheet for sanitary masks of the present invention is not limited to the laminated structure shown in the above-mentioned embodiment, and may have various laminated structures as long as the effects of the present invention are not impaired.

[0092] The thus obtained sheet for sanitary masks of the present invention can itself be used as a sanitary mask. As for this sanitary mask, there is one in which the sanitary mask body that covers the face and the ear loops that fix the wearing state of the sanitary mask body are integrally formed using the sheet for sanitary masks of the present invention. In another case, only the mask body is formed using the sheet for sanitary masks of the present invention, and the ear loops made of a separate material (e.g., rubber strings or elastic nonwoven fabric) are attached. It is preferable that at least the mask body is provided with the sheet for sanitary masks of the present invention.

[0093] The sheet for sanitary masks of the present invention can be used as a filter sheet that can be attached to and detached from a sanitary mask, in addition to being used as a sanitary mask itself. For example, the sheet for sanitary masks of the present invention can be used as a filter sheet in a sanitary mask that includes a mask body and a filter sheet disposed inside the mask body. This filter sheet preferably has a three-dimensional shape similar to the mask body.

[0094] In addition, the sanitary mask and the filter sheet to which the sheet for a sanitary mask of the present invention is applied may have a three-dimensional shape or may be rectangular in a plan view. Furthermore, the sanitary mask and the filter sheet may have several pleats extending in the horizontal direction. EXAMPLES

[0095] The present invention will be described in more detail below based on examples, but the present invention is not limited thereto. In the examples, "parts" and "%" are all based on mass unless otherwise specified. In Table 1 below, "-" means that the item does not have a corresponding value, etc.

[0096] Example 1 A sample sheet for a sanitary mask of Example 1 shown in FIG. 2 was produced by the manufacturing method shown in FIGS. 11(A) to (C). The base sheet 9 was made of a stretchable sheet 96 shown in FIG. 8, and was produced by the following method. The average fiber diameter is 18μm and the basis weight is 18g / m 2 Two sheets of spunbond nonwoven fabric made of polypropylene (hereinafter also referred to as PP) resin were used, and multiple elastic filaments with a diameter of 100 μm were placed between the two nonwoven fabrics. The total basis weight of the elastic filaments was 9 g / m 2 This laminated sheet was passed between a pair of grooved rolls to develop elasticity, and an elastic sheet 96 was produced. The uneven nonwoven fabric 8 was produced by the following method. The average fiber diameter is 15μm and the basis weight is 18g / m 2 A spunbond nonwoven fabric made of PP resin was prepared as a protective sheet. Then, fibers spun by electrospinning were deposited on this protective sheet, and filter nonwoven fabric A was laminated on the protective sheet to prepare raw material nonwoven fabric 800 for the uneven nonwoven fabric. 11(A)-(C), the elastic sheet 96 was stretched 1.5 times, and the raw nonwoven fabric 800 of the uneven nonwoven fabric was layered and joined to produce a sheet sample for a sanitary mask. The elastic sheet 96 had a breaking elongation of 70%, and the uneven nonwoven fabric raw roll was layered and joined in a state in which the elastic sheet 96 was stretched to 71% of the breaking elongation. The average fiber diameter, density, and basis weight of the filter nonwoven fabric A were as shown in Table 1. The height of the convex portions, the interval between the convex portions, and the ratio (S1 / S0) of the surface area S1 of the unevenness per unit area S0 of the uneven nonwoven fabric 8 were as shown in Table 1. A sheet measuring 50 mm in one stretching direction and 25 mm in the axial direction was cut out from the prepared sanitary mask sheet to prepare a sanitary mask sheet sample of Example 1.

[0097] Example 2 A sample sheet for a sanitary mask of Example 2 was produced in the same manner as in Example 1, except that a sheet for a sanitary mask was produced by overlapping and bonding raw nonwoven fabric 800 of the uneven nonwoven fabric under a state in which the elastic sheet was stretched to 1.3 times (43% of the breaking elongation rate). The breaking elongation rate of the elastic sheet 96 was 70%, and the uneven nonwoven fabric raw roll was laminated and bonded under a state in which the elastic sheet 96 was stretched to 43% of the breaking elongation rate. In the sample sheet for a sanitary mask of Example 2, the height of the convex parts, the interval between the convex parts, and the ratio (S1 / S0) of the surface area S1 of the uneven parts per unit area S0 of the uneven nonwoven fabric 8 were as shown in Table 1.

[0098] Comparative Example 1 A sheet for a sanitary mask was cut out from Unicharm Super Comfortable Mask (product name, manufactured by Unicharm Corporation) measuring 50 mm in one stretching direction and 25 mm in the axial direction to prepare a sample of the sheet for a sanitary mask in Comparative Example 1.

[0099] Comparative Example 2 A sample of the sanitary mask sheet of Comparative Example 2 was prepared by cutting out a sheet of PITTA MASK (product name, Arax Co., Ltd.) measuring 50 mm in one stretching direction and 25 mm in the axial direction.

[0100] For each of the above-mentioned Examples and Comparative Examples, the values ​​of the shrinkage rate in the width direction at 50% elongation, the tensile modulus E2, the tensile modulus E1A, and the tensile modulus E2 / tensile modulus E1A were measured based on the above-mentioned (Method of measuring shrinkage rate) and (Method of measuring tensile modulus). Moreover, the tensile test results of Example 1, Comparative Example 1, and Comparative Example 2 are shown in Fig. 12, and an enlarged view of the area within the frame of the horizontal axis 0-50 mm and the vertical axis 0-10 N of the tensile test results in Fig. 12 is shown in Fig. 13.

[0101] [Table 1]

[0102] As shown in Table 1, Fig. 12 and Fig. 13, in comparison with the comparative examples, the examples have an inflection point in the tensile modulus, and in addition, the shrinkage rate in the width direction at 50% elongation is low, and it can be inferred that there is no structural change in the filter nonwoven fabric and no effect on the capture efficiency. [Explanation of symbols]

[0103] 1 Convex part of the first surface 2 Recess on the first surface 3 Convex part of the second surface 4 Recess on second surface 8 Uneven non-woven fabric A Filter nonwoven fabric 81 Protective Sheet 9. Base sheet 94 Non-elastic nonwoven fabric 95 Elastic Filament 96 Elastic Sheet 97 Perforated Sheet 98 Support member 21 Junction 10. Sheets for sanitary masks 1S 1st page 1R 2nd page 800 Uneven nonwoven fabric roll

Claims

1. The mask body is provided with a sanitary mask sheet that covers at least a person's mouth and nose, The sheet for sanitary masks, It has elasticity in at least one direction, When the sheet is stretched in the one direction by 50% of the initial length, the shrinkage rate at the position where the width in the axial direction perpendicular to the one direction is narrowest is within 10%; The filter nonwoven fabric is composed of fibers having an average fiber diameter of 50 nm or more and 3000 nm or less. Hygienic mask.

2. A sanitary mask as described in claim 1, wherein the sanitary mask sheet does not exhibit elasticity in the axial direction.

3. The mask body is provided with a sanitary mask sheet that covers at least a person's mouth and nose, The sheet for sanitary masks is formed by laminating, on the surface of a base sheet having elasticity in at least one direction, a nonwoven fabric having a tensile modulus higher than that of the base sheet, the nonwoven fabric having convex portions and concave portions arranged alternately in a ridge-groove pattern, The uneven nonwoven fabric includes a filter nonwoven fabric composed of fibers having an average fiber diameter of 50 nm or more and 3000 nm or less. Hygienic mask.

4. 4. The sanitary mask according to claim 3, wherein when the sheet for a sanitary mask is stretched in a direction perpendicular to the extension direction of the convex portions of the uneven nonwoven fabric, the convex portions are stretched, and the uneven nonwoven fabric has an inflection point at which the tensile modulus changes by 100% or more when a tensile load is applied thereto.

5. The sanitary mask according to claim 4, wherein the rate of change (E2 / E1×100) of the maximum value E2 of the tensile modulus after the inflection point to the maximum value E1 of the tensile modulus before the inflection point is 200% or more.

6. The sanitary mask according to any one of claims 3 to 5, wherein in the uneven nonwoven fabric, the distance between adjacent convex portions is 1 mm or more and 6 mm or less.

7. The mask comprises a mask body and a filter sheet that is detachable from the mask body. The filter sheet is A sheet for a sanitary mask having elasticity in at least one direction, a sheet for a sanitary mask, wherein when the sheet is stretched in the one direction by 50% longer than the initial length, the shrinkage rate at the position where the width in the axial direction perpendicular to the one direction is narrowest is within 10%; Or, A sheet for a sanitary mask, comprising a base sheet having elasticity in at least one direction, and a nonwoven fabric having a tensile modulus higher than that of the base sheet, the nonwoven fabric having convex and concave portions arranged alternately in a ridge-groove pattern, the nonwoven fabric being laminated on the surface of the base sheet. A sanitary mask.

8. A sheet for a sanitary mask having elasticity in at least one direction, a sheet for a sanitary mask, wherein when the sheet is stretched in the one direction by 50% longer than the initial length, the shrinkage rate at the position where the width in the axial direction perpendicular to the one direction is narrowest is within 10%; Or, A sheet for a sanitary mask, comprising a base sheet having elasticity in at least one direction, and a nonwoven fabric having a tensile modulus higher than that of the base sheet, the nonwoven fabric having convex and concave portions arranged alternately in a ridge-groove pattern, the nonwoven fabric being laminated on the surface of the base sheet. A method for using a sheet for a sanitary mask, comprising using the sheet as a detachable filter sheet for a mask body of a sanitary mask.

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