JP7625428B2 - Mask Sheet - Google Patents

Description

The present invention relates to a mask sheet.

In recent years, with the spread of infectious diseases, people are increasingly wearing masks that cover their mouths and noses for long periods of time. Some of these masks are foldable, and various technologies have been proposed to make them foldable.
For example, U.S. Patent No. 5,399,633 describes a personal respiratory protection device having a main body with a first portion, a second portion separated from the first portion by a first boundary line, and a third portion separated from the second portion by a second boundary line, the personal respiratory protection device being foldable into a substantially flat configuration along a bisection fold extending through the first portion, the second portion, and the third portion.
Patent Document 2 describes a dust mask having a nonwoven fabric sheet as a mask base material with embossed lines. This dust mask is foldable by folding the mask vertically along the embossed lines toward the inside of the mask.

Special Publication No. 2002-537009 JP 2006-218079 A

When using one mask for a long time, there are occasions when the mask is removed and worn again during meals, etc. When the removed mask is temporarily placed on a desk or put in a pocket, it is often desirable from a hygienic standpoint to fold the mask neatly so that the surface in contact with the skin does not come into contact with germs and become contaminated. In addition to folding the surface in contact with the skin inward, the surface that does not come into contact with the skin may be folded inward to prevent the scattering of particles such as pollen. However, when a conventional mask is folded, a fold line is generated at the folded portion, and when the mask is opened and unfolded again, the surface covering the mouth and nose may not return to its original state and may become deformed. In other words, the restoration of the mask after folding is poor, and not only the appearance but also the performance of maintaining a primary hygiene aspect may be deteriorated.
Furthermore, even in the case of foldable masks as described in Patent Documents 1 and 2, in order to maintain the performance of the mask, it is only possible to fold it into a designed shape. In other words, the user cannot fold the mask into a small size of their choice while maintaining hygienic performance.
Conventional masks still had some room for improvement in terms of being able to be folded and made small while still taking hygiene into consideration.

In view of the above problems, the present invention relates to a mask sheet that can be rolled up to a desired size, and even when rolled up, is unlikely to deform when reused and has good restorability.
The present invention also relates to a mask having the mask sheet.
Furthermore, the present invention relates to a suitable method for using the mask sheet and the mask.

The present invention provides a mask sheet having a first side which is a side that comes into contact with a user's skin and a second side which is a side opposite to the first side, and on the outermost surface of one or both of the first side and the second side , there are a plurality of convex portions protruding outward in a thickness direction and a concave portion sandwiched between the plurality of convex portions, and the concave portions are arranged continuously in one direction in a plan view.

The mask sheet and mask of the present invention can be rolled up to a size of any desired size, and even if it is rolled up, it is unlikely to deform when reused and has good recovery properties.
Furthermore, according to the method for using a mask sheet and the method for using a mask of the present invention, the mask sheet and the mask can be used suitably.

FIG. 1 is a perspective view showing a schematic diagram of one embodiment of a mask sheet of the present invention. FIG. 2 is a plan view showing a schematic example of convex portions and concave portions present on the outermost surface of the mask sheet of the present invention. FIG. 2 is a side view showing a schematic diagram of the mask sheet shown in FIG. 1 in a rolled up state. FIG. 2 is a front view showing a schematic view of the mask sheet shown in FIG. 1 rolled up and placed in a pocket. FIG. 2 is a plan view showing another example of the convex portions and concave portions present on the outermost surface of the mask sheet of the present invention. 1 is an explanatory diagram showing the definition of "continuous in one direction" for a recess. (A) and (B) show an example where a given recess corresponds to "continuous in one direction". (C) and (D) show an example where a given recess does not correspond to "continuous in one direction". FIG. 1 is a cross-sectional view illustrating a schematic diagram of one embodiment of a mask sheet according to the present invention. FIG. 2A is a perspective view showing a state in which the mask sheet of the present invention is worn, and FIG. 2B is a perspective view showing the mask sheet shown in FIG. 2A as viewed from the inside. FIG. 1 is a perspective view showing a method for using the mask sheet of the present invention as a filter sheet.

A preferred embodiment of the mask sheet of the present invention will be described with reference to the drawings. The mask sheet of the present invention is a material used for a mask, and includes both the raw material before being applied to the mask and the material incorporated into the mask.
In the present invention, unless otherwise specified, the direction corresponding to the top and bottom of the human body during use is referred to as the up-down direction, and the direction corresponding to the left and right of the human body is referred to as the left-right direction. In addition, a surface to which the up-down and left-right directions belong is referred to as a plane, and a direction perpendicular to the plane direction is referred to as a thickness direction.

The mask sheet of the present invention has a first side which is a side that contacts the skin of a user, and a second side which is a side opposite to the first side. On the outermost surface of one or both of the first and second sides, there are a plurality of convex portions protruding outward in the thickness direction, and a concave portion sandwiched between the plurality of convex portions.
The mask 20 shown in FIG. 1 includes a pair of mask sheets 10, 10, which is a preferred embodiment of the mask sheet of the present invention. The pair of mask sheets 10, 10 of this embodiment are arranged with the first surfaces 1S facing each other. Each mask sheet 10 has a flat outermost surface of the second surface 1R, and has a convex portion 1 and a concave portion 2 on the outermost surface of the first surface 1S. As shown in FIG. 2, the concave portions 2 are arranged continuously in one direction in a plan view. In FIG. 2, the "one direction" in which the concave portions 2 are continuous is the short side direction X of the mask sheet 10, which has a longitudinal direction Y and a short side direction X perpendicular to the longitudinal direction Y. This short side direction X is the up-down direction in the mask 20 shown in FIG. 1.
The mask sheet 10 shown in FIG. 2 has the convex portions 1 and concave portions 2 arranged in such a pattern over the entire sheet surface, and becomes a raw material (for example, a long roll) before being applied to the mask 20.

Since the outermost surface of one or both of the first surface 1S and the second surface 1R has projections and recesses 2 that are continuous in one direction, the recesses 2 become the starting points for folding the mask sheet 10 and the mask 20. This makes it easy to roll and fold the mask sheet 10 and the mask 20. That is, the mask can be folded into a small shape when not in use.
In addition, stress is likely to concentrate in the continuous recesses 2, making the sheet 10 easy to bend. As a result, even when the sheet 10 for masks is folded small, the sheet 10 for masks is likely to bend preferentially at the recesses 2 rather than at other portions. As a result, the sheet 10 for masks is less likely to be crushed by folding, and the performance of the sheet 10 for masks is more likely to be maintained. In addition, preferential bending at the recesses 2 makes the sheet 10 for masks less likely to develop creases. In other words, the sheet 10 for masks is less likely to deform when reused, and has good restorability.

The direction in which the recesses 2 are continuous is not limited to that shown in FIG. 2, and can be any direction in a plan view. For example, it may be the short-side direction X (the vertical direction of the mask 20) or the long-side direction Y (the horizontal direction of the mask 20). However, as described below, from the viewpoint of being able to roll and fold into a smaller shape, it is preferable that the one direction is the short-side direction X.

That is, as shown in FIG. 1, it is preferable that the recesses 2 are continuous in the up-down direction of the mask 20 (the short-side direction X of the mask sheet 10).
The shape of the mask 20 is generally such that the length in the left-right direction is greater than the length in the up-down direction. Therefore, when the mask 20 is rolled in the left-right direction, the length (up-down direction) of the rod-shaped mask 20 is shorter than when it is rolled in the other direction. That is, by rolling the mask 20 in the left-right direction, the mask 20 can be folded into a small size. At this time, since there are recesses 2 that are continuous in the up-down direction, it is easy to fold the mask 20 in the left-right direction starting from the recesses 2. As a result, the mask 20 can be rolled and folded into a short rod shape.

The number of recesses 2 arranged continuously in one direction may be only one, or may be multiple, as shown in Figs. 1 and 2. When the mask sheet 10 has only one recess 2, the mask sheet 10 can be folded in half by bending the mask sheet 10 from one recess 2. On the other hand, when the mask sheet 10 has multiple recesses 2, the mask sheet 10 can be folded from multiple recesses 2 to roll into a rod shape as shown in Fig. 3. Furthermore, as shown in Fig. 4, the mask sheet 10 can be rolled up to any size and put into a pocket. In addition, the mask 20 having the mask sheet 10 can be folded with the first surface 1S facing inward, folded in half, and then rolled up, thereby avoiding contact between the first surface 1S and the second surface 1R. As a result, the first surface 1S that comes into contact with the user's skin can be kept hygienic.
That is, from the viewpoint of enabling the sheet to be rolled and folded into a smaller shape, it is preferable that the recesses 2 are arranged in a plurality of stripes along a direction intersecting one direction. Moreover, it is preferable that such a plurality of stripes of recesses 2 continuous in one direction are arranged over the entire sheet surface of the mask sheet 10 as shown in Fig. 2. Furthermore, it is preferable that the recesses 2, 2 are arranged at equal intervals.

The continuously arranged recesses 2 may be continuous in one direction in a straight line as shown in Fig. 2, or may be continuous in one direction (first direction S1 or second direction S2) while meandering as shown in Fig. 5. In either form, the mask sheet 10 can be folded starting from the continuous recesses 2. However, from the viewpoint of making it easier to reduce the thickness of the mask sheet 10 when it is in a folded state, it is preferable that the recesses 2 are linear.
The linear recesses 2 can be typically formed by providing an unevenness of a ridge-and-furrow structure on the outermost surface as shown in Fig. 2. Therefore, from the viewpoint of forming the linear recesses 2, it is preferable that the protrusions 1 and the recesses 2 are unevenness of a ridge-and-furrow structure.
The term "continuous in one direction" means that an approximation line obtained from a curve consisting of the path of a recess between multiple protrusions is in the region between the multiple protrusions. Here, the approximation line is a line extending in the direction along the arrangement direction of the multiple recesses, and the direction in which the approximation line extends is the "one direction" described above.
For example, in the arrangement of the convex portion 1 and the concave portion 2 shown in Fig. 6(A), the approximate straight line obtained from the path 3 of the concave portion is the approximate straight line L1 shown in Fig. 6(B). Since the approximate straight line L1 is in the region sandwiched between the convex portions 5 (shaded convex portions 1) on both sides of the path 3 of the concave portion, it can be said that the path 3 of the concave portion is continuous in one direction. On the other hand, the approximate straight line L2 shown in Fig. 6(D) is obtained from the path 4 of the concave portion shown in Fig. 6(C). However, since the approximate straight line L2 does not fall within the region sandwiched between the convex portions 5 (shaded convex portions 1) on both sides of the path 4 of the concave portion, it does not fall under the "continuous in one direction" described above.

The recesses 2 may be arranged in a plurality of stripes along a plurality of directions in a plan view. For example, in the top surface of the mask sheet 10 shown in Fig. 5, a plurality of continuous recesses 2 are arranged in a direction intersecting the first direction S1 while meandering in the first direction S1, and a plurality of continuous recesses 2 are arranged in a direction intersecting the second direction S2, which is different from the first direction S1, in a form different from the form shown in Fig. 2. The first direction S1 and the second direction S2 are both directions intersecting the longitudinal direction Y and the lateral direction X of the mask sheet 10.
In this embodiment, the convex portions 1 are arranged in a scattered manner. The concave portions 2 between the scattered convex portions 1, 1 are connected to form grooves, and the concave portions 2 are arranged in a mesh-like manner. In this manner, the concave portions 2 may all be connected to form one. However, even if the concave portions 2 are connected to one another in a mesh-like manner or the like, it is preferable that a plurality of concave portions 2 that are continuous in one direction are arranged in parallel to each other, and the concave portions 2 essentially function as a plurality of grooves. If the concave portions 2 are essentially composed of a plurality of grooves, it becomes possible to roll the mask sheet 10 into a rod shape, starting from each of the parallel grooves, and fold it small in a plurality of directions.

From the viewpoint of making the unevenness of the outermost surface of the mask sheet 10 clear, the height of the convex portion 1 (the distance that the convex portion 1 protrudes outward in the thickness direction) is preferably 1 mm or more, more preferably 1.5 mm or more, and even more preferably 2 mm or more. Furthermore, from the viewpoint of making it possible to fold it into a smaller shape, the height of the convex portion 1 is preferably 4 mm or less, more preferably 3.5 mm or less, and even more preferably 3 mm or less. The height of the convex portion 1 can be rephrased as the difference in height between the convex portion 1 and the concave portion 2, or the depth of the concave portion 2.

Since the recesses 2 are arranged continuously in one direction X, the protrusions 1 between adjacent recesses 2, 2 have a certain width in a direction perpendicular to one direction X. From the viewpoint of creating a buckling starting point in the recesses 2 and making it easy to fold, the width of this protrusion 1 is preferably 1 mm or more, more preferably 1.5 mm or more, and even more preferably 2 mm or more. In addition, from the viewpoint of providing many recesses 2 and making it possible to roll and fold the mask sheet 10 into a small shape, the width of the protrusion 1 is preferably 6 mm or less, more preferably 5 mm or less, and even more preferably 4 mm or less. The width of the protrusion 1 can be rephrased as the distance between adjacent recesses 2, 2.

Next, we will explain the components of the mask sheet 10 of the present invention.

The mask sheet 10 of the present invention may be composed of one sheet, or may be composed of a plurality of sheets laminated together. Specific examples of a laminate of a plurality of sheets include a laminate of an elastic sheet and a concave-convex sheet. In this case, the concave-convex sheet is preferably composed of a filter layer (a layer made of fibers having an average fiber diameter of 3000 nm or less) and a spunbond nonwoven fabric layer that protects the filter layer. By including a filter layer, or by having a sheet including a filter layer have an uneven shape, the ability to capture fine particles in the air is extremely high, and flexibility is also increased. In addition, by including the above-mentioned ultrafine fibers in the filter layer, the density is increased, the number of contact points between the fibers is increased, and the adhesion of the welded part described below can be improved.
From this viewpoint, the average fiber diameter of the constituent fibers of the filter layer is more preferably equal to or less than 2000 nm, and further preferably equal to or less than 1000 nm.
In addition, from the viewpoint of ensuring appropriate breathability and allowing the user of the mask sheet 10 to breathe easily, the average fiber diameter of the constituent fibers of the filter layer is preferably 50 nm or more, more preferably 100 nm or more, and even more preferably 200 nm or more.

The average fiber diameter of the constituent fibers of the filter layer 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.
After carefully peeling off the masking material to confirm how many layers are formed, the layer with the smallest fiber diameter (the layer that functions as a filter material) is taken as the fiber layer to be measured. From the two-dimensional image obtained by SEM observation, 500 fibers are arbitrarily selected, excluding defects such as fiber clumps, fiber intersections, 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 taken as the average fiber diameter of the fibers constituting the fiber layer to be measured.

As long as the mask sheet 10 has at least a concave-convex sheet having a convex portion 1 and a concave portion 2, the other sheet may be a concave-convex sheet or a flat sheet. In particular, as shown in FIG. 7, the mask sheet 10 is preferably a laminate of a concave-convex sheet 11 having a convex portion 1 and a concave portion 2 and a flat sheet 12 having a flat shape. When these are laminated one by one, the concave-convex sheet 11 side becomes the concave-convex surface 1A having the convex portion 1 and the concave portion 2 on the outermost surface, and the flat sheet 12 side becomes the flat surface 1B. That is, the mask sheet 10 as a whole has a structure similar to that of a shutter-type bath cover or a single-sided cardboard, and can be freely rolled up to any size at any location in the same way. Moreover, the flat sheet 12 acts on the concave-convex sheet 11 to maintain the shape of the sheet surface, so the mask sheet 10 does not develop creases and has even higher restorability.

When the flat sheet 12 is used as a component of the mask sheet 10, it is preferable that the flat sheet 12 is an elastic sheet. If an elastic sheet is used for the flat sheet 12, the unevenness can be suitably formed on the outermost surface of the mask sheet 10 when manufacturing the mask sheet 10 as follows. For example, by bonding a part of a sheet that will be the precursor of the uneven sheet 11 to the stretched elastic sheet and then releasing the stretched state, the precursor of the uneven sheet 11 shrinks and the unevenness can be formed. With such a configuration, a hollow portion is created between the uneven sheet 11 and the flat sheet 12, and the bending stress when the mask is bent is reduced.

In this specification, "elastic" refers to the property of applying force to a sheet in one direction to elongate it by 50% (1.5 times the natural length before elongation), and then shrinking to an elongation rate of 0% to 10% (1 to 1.1 times the natural length before elongation) when the load is removed. In contrast, in this specification, "non-elastic" refers to the property of having an elongation rate of more than 10% when subjected to a similar test, or the property of breaking when elongated by 50%. According to this standard, it is possible to distinguish whether the sheet used as a component of the mask sheet 10 is an elastic sheet or a non-elastic sheet.
Examples of the stretchable sheet include nonwoven fabrics containing elastic fibers as constituent fibers, composite materials of nonwoven fabrics made of nonelastic fibers and elastic bodies (e.g., elastic filaments), and cotton-mixed nonwoven fabrics of elastic fibers and nonelastic fibers. In measuring the "stretchability" described above, when the sheet to be measured is, for example, a flat sheet 12 and a concave-convex sheet 11 laminated thereon, the sheet 10 for sanitary masks is left in a natural state without external force and cut into 20 mm x 50 mm pieces using a single-edged blade (product number: FAS-10) manufactured by Feather Safety Razor Co., Ltd. Thereafter, the joint at the interface between the flat sheet 12 and the concave-convex sheet 11 is cut using a razor, cutter, scissors, or the like to separate the flat sheet 12 and the concave-convex sheet 11, and each cut piece is stretched in the longitudinal direction to evaluate the "stretchability".

On the other hand, when the embossed sheet 11 is used as a component of the mask sheet 10, it is preferable that the embossed sheet 11 is a non-stretchable sheet. By using a non-stretchable sheet for the embossed sheet 11, it is easier to prevent the rolled up mask from opening unintentionally.

The mask sheet 10 of the present invention can be used in a mask in various ways. For example, in the embodiment shown in Figures 1 and 8, not only the mask body but also the ear loops are made of the mask sheet 10, but instead, only the mask body may be made of the mask sheet 10, and the ear loops may be made of other materials, such as rubber strings or elastic nonwoven fabric. In any case, these embodiments are forms in which the mask body has the mask sheet 10 of the present invention.
Alternatively, as shown in Fig. 9, the mask sheet 10 of the present invention may be used as a filter sheet that is detachable from the mask body. In this embodiment, the mask has a mask body and a filter sheet, and the filter sheet has the mask sheet 10 of the present invention.
These masks use the mask sheet 10 of the present invention, and therefore can be rolled and folded starting from the recess 2.

The present invention will be described in more detail below with reference to examples, but the present invention should not be construed as being limited thereto.

Example 1
A mask sheet having a ridge-and-groove structure on the outermost surface was produced by laminating a concave-convex sheet and a flat sheet, as shown in Figures 2 and 7. The convex portions and concave portions of the ridge-and-groove structure were both linear. The height of the convex portions was 2.5 mm, and the width of the convex portions was 3 mm.
The mask sheet was cut and joined so that the extension direction of the convex and concave parts coincided with the vertical direction of the mask, and a mask sample was produced in which the first surface that comes into contact with the user's skin is an uneven surface, as shown in Figure 1. This was used as the mask sample of Example 1.
By folding starting from the multiple recesses, the mask sample of Example 1 was rolled up in the left-right direction into a rod shape as shown in Fig. 3, and the left-right length of the mask sample in a plan view was reduced to 1/6. The rolled mask sample was left to stand for 10 seconds without applying external force, and then the left-right length of the mask sample in a plan view was measured.

(Comparative Example 1)
A rectangular pleated mask (product name: Azfine Fit Surgical Mask, manufactured by AzScience Corporation) was used as a mask sample of Comparative Example 1.
The mask sample of Comparative Example 1 was rolled up and down into a rod shape by folding from the pleats, and the vertical length of the mask sample in plan view was reduced to 1/6. The rolled mask sample was left to stand for 10 seconds without applying any external force, and then the vertical length of the mask sample in plan view was measured.

(Calculation of state maintenance rate)
The state maintenance rate was calculated by dividing the length of the mask sample in the rolled state in the roll direction by the length of the mask sample after leaving it still for 10 seconds for each of the mask samples of Example 1 and Comparative Example 1. Note that the "roll direction" refers to the direction in which the mask sample was rolled, and in the mask sample of Example 1, the left-right direction corresponds to the roll direction, and in the mask sample of Comparative Example 1, the up-down direction corresponds to the roll direction.
The closer the state maintenance rate is to 100%, the easier it is for the mask sample to maintain its rolled state.
The results are shown in Table 1.

As shown in Table 1, in the mask sample of Example 1, even when left undisturbed for 10 seconds in a rolled state, the length in the rolled direction in a plan view did not change, and the state maintenance rate was 100%. In other words, the state maintenance rate value was superior to that of the mask sample of Comparative Example 1, whose length in the rolled direction increased when left undisturbed for 10 seconds in a rolled state.
That is, the mask sample of Example 1 could be reduced in size to 1/6 of its original length and maintained in that reduced state.

1 Convex portion 2 Concave portions 3, 4 Path of the concave portion 5 Convex portions on both sides of the path of the concave portion 10 Mask sheet 11 Concave-convex sheet 12 Flat sheet 1A Concave-convex surface 1B Flat surface 1S First surface 1R Second surface 20 Mask L1, L2 Approximate straight line S1 First direction S2 Second direction X Short side direction Y Longitudinal direction

Claims (9)

The mask has a first surface that contacts the skin of a user and a second surface that is opposite to the first surface,
On an outermost surface of one or both of the first surface and the second surface, there are a plurality of convex portions protruding outward in a thickness direction and a plurality of concave portions sandwiched between the convex portions,
The mask sheet, in which the recesses are continuously arranged in one direction in a plan view, is a laminate of a concave-convex sheet having the convex portions and the recesses and a flat sheet having a flat shape, the flat sheet being an elastic sheet,
A mask having a mask body constituted by the mask sheet . The mask according to claim 1 , wherein the mask sheet constitutes ear loops. 3. The mask according to claim 1, wherein the recesses are arranged in a plurality of stripes along a direction intersecting the one direction in a plan view, and the mask is foldable to an arbitrary size. A method of using a mask comprising rolling and folding the mask according to any one of claims 1 to 3 starting from the recess. The mask has a first surface that contacts the skin of a user and a second surface that is opposite to the first surface,
On an outermost surface of one or both of the first surface and the second surface, there are a plurality of convex portions protruding outward in a thickness direction and a plurality of concave portions sandwiched between the convex portions,
the concave portions are continuously arranged in one direction in a plan view, the mask sheet being formed by laminating a concave-convex sheet having the convex portions and the concave portions and a flat sheet having a flat shape,
The sheet for a mask, wherein the flat sheet is a stretchable sheet. The mask sheet according to claim 5, wherein the height of the protrusions is 3 mm or less. The mask sheet according to claim 5 or 6 , wherein the recesses are arranged in a plurality of stripes along a cross direction intersecting the one direction in a plan view, and the mask sheet is foldable to an arbitrary size. A mask body and a filter sheet that is detachable from the mask body.
A mask, comprising the filter sheet according to any one of claims 5 to 7 . A method for using the mask sheet according to any one of claims 5 to 7 as a filter sheet that is detachable from a mask body .

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