Manufacturing method of mask

Abstract

To provide a technique for suppressing deviation of the size of a pleated sheet from a design value.SOLUTION: A method for manufacturing masks comprises: a pleat forming step of forming a plurality of pleats along the conveyance direction on a mask body continuum including a nonwoven fabric sheet which is made of a fiber containing polylactic acid as a main component and has a width shrinkage ratio of 2% or less; and an embossing step of embossing the mask body continuum having the plurality of pleats formed thereon.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a mask. [Background technology]

[0002] In recent years, masks made of pleated nonwoven fabric have become known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-2483 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the process of forming pleats in a sheet, if the size of the folded sheet deviates from the design value of the mask, the embossing cannot be performed to the designed width in the subsequent embossing process, resulting in defective embossing.

[0005] An object of the present invention is to provide a technique for preventing the size of a pleated sheet from deviating from the design value. [Means for solving the problem]

[0006] A method for manufacturing a mask according to one aspect of the present invention includes the steps of: A pleat forming process for forming a plurality of pleats along a conveying direction on a continuous mask body including a nonwoven fabric sheet made of fibers mainly composed of polylactic acid and having a width shrinkage rate of 2% or less; an embossing step of embossing the mask body continuous body on which the plurality of pleats are formed; Includes. Effect of the Invention

[0007] According to the present invention, it is possible to prevent the size of a pleated nonwoven fabric sheet from deviating from the design value. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of the appearance of a mask according to an embodiment. [Diagram 2] FIG. 2 is a plan view of the mask according to the embodiment. [Diagram 3] FIG. 3 is an exploded perspective view showing a layered structure of the mask according to the embodiment. [Figure 4] FIG. 4 is a flowchart showing an outline of a method for manufacturing a mask according to an embodiment. [Diagram 5] FIG. 5 is a diagram showing a mask manufacturing apparatus according to the embodiment. [Figure 6] FIG. 6 is a schematic diagram showing a pleat forming step in the mask manufacturing method according to the embodiment. [Figure 7] FIG. 7 is a schematic diagram showing a pleat forming step in a mask manufacturing method according to a comparative example. [Figure 8] FIG. 8 is a table comparing the mask according to the embodiment with the mask according to the comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a mask according to an embodiment of the present invention will be described with reference to the drawings. Note that the configurations of the following embodiments are merely examples, and the present invention is not limited to the configurations of these embodiments.

[0010] <Embodiment> FIG. 1 is an external perspective view of a mask according to an embodiment. FIG. 2 is a plan view of the mask 1 as viewed from the skin side. The mask 1 has a left-right direction that corresponds to the left-right direction of the wearer when worn by the wearer (hereinafter, abbreviated as "worn state"), and a width direction that is perpendicular to the left-right direction. The width direction corresponds to the top and bottom of the wearer. The mask 1 has a length along the left-right direction and a width along the width direction perpendicular to the left-right direction. In addition, in the worn state of the mask 1, the side facing the wearer's skin (inner side when worn) is the skin side, and the opposite side to the skin side (outer side when worn) is the non-skin side. Furthermore, the direction connecting the skin side and the non-skin side is the thickness direction. In addition, the view from the thickness direction is a plan view.

[0011] As shown in FIG. 1 and FIG. 2, the mask 1 has a mask body 2, ear straps 3, 4, edge tapes 5, 6, and a nose fitter 7. More specifically, the mask body 2 is formed in a state where multiple layers of sheet-like breathable material are laminated, and has a size that can cover the wearer's mouth and nose. The ear straps 3, 4 are formed of a string-like elastic material. As shown in FIG. 1 and FIG. 2, the edge tapes 5, 6 are attached to both ends of the skin side and non-skin side of the mask body 2 in the left and right direction. Then, the edge tapes 5, 6 attached to the skin side of the mask body 2 and the respective ends of the ear straps 3, 4 are heat-welded, so that the ear straps 3, 4 form annular loops on both the left and right sides of the mask body 2. As shown in FIG. 2, the welding areas 15, 16 of the edge tapes 5, 6 to which the ends of the ear straps 3, 4 are heat-welded are designed to be wider than the areas of the other edge tapes 5, 6.

[0012] The string-like elastic material constituting the ear straps 3, 4 is formed, for example, from a woven band of rubber thread and cotton, a woven net of resin filaments, elastic nonwoven fabric, etc. Both ends of such string-like material are heat-welded to the welding areas 15, 16 of the edge tapes 5, 6 on the left and right sides of the skin-facing side of the mask body 2 as shown in Fig. 2, thereby forming the ear straps 3, 4 in a loop shape on the left and right sides of the mask body 2, with one end of the material as the starting point and the other end of the material as the ending point.

[0013] The mask body 2 is made of various sheets such as breathable nonwoven fabrics, and is a laminate of multiple sheets. The multiple sheets are fixed to each other by heat welding using an embossing roll at welding parts 9U, 9D, 9L, and 9R near the upper, lower, left, and right edges in FIG.

[0014] The mask body 2 is formed with a plurality of pleats 8 extending in the left-right direction. In this embodiment, three pleats are formed. The pleats 8 are maintained by preventing their deployment by the edge tapes 5, 6 at the ends on both the left and right sides. Therefore, when the mask 1 is not worn, the mask body 2 can be made flat and not bulky. On the other hand, when the mask 1 is worn, the mask body 2 is stretched in the vertical direction to deploy the pleats 8. The mask body 2 becomes a dome-shaped three-dimensional shape that bulges toward the non-skin side by spreading the pleats 8. This forms a space between the mask body 2 and the wearer's mouth, making it easier for the wearer to breathe.

[0015] The nose fitter 7 is a member fixed to the mask body 2 in an upper portion of the mask body 2 with its longitudinal direction extending in the left-right direction of the mask body 2. The nose fitter 7 is fixed to the mask body 2 in a state where it is sandwiched between the sheet-like breathable materials that make up the mask body 2. Alternatively, the nose fitter 7 may be fixed to the surface of the mask body 2. The nose fitter 7 is deformable to an appropriate shape by the wearer pressing it with his / her fingers. The nose fitter 7 is made of a plastically deformable material that has a certain degree of strength and maintains its shape even after the pressure is released. By providing such a nose fitter 7 on the upper part of the mask body 2 in Figures 1 and 2, the wearer can close the gap between the nose and the mask body 2.

[0016] 3 is an exploded perspective view showing the layered structure of the sheet members constituting the mask body 2 of the mask according to the embodiment. In this embodiment, the mask body 2 has a laminate in which a plurality of sheets are layered. In this embodiment, the mask body 2 has a three-layer structure in which a top sheet 20, a filter sheet 21, and a mouth sheet 22 (an example of the "nonwoven fabric sheet" as referred to in this application) are layered in this order from the non-skin facing side to the skin facing side.

[0017] The top sheet 20 is made of a material that is breathable and has the durability required to withstand the external environment. In this embodiment, for example, spunlace nonwoven fabric is used for the top sheet 20. The filter sheet 21 is made of a material with high particle capture performance. For example, electret-treated meltblown nonwoven fabric is used for the filter sheet 21, and the filter sheet 21 captures fine particles by static electricity. The mouth sheet 22 is made of a nonwoven fabric made of a resin mainly composed of polylactic acid (PLA). Polylactic acid is a biodegradable resin that is hydrolyzed by moisture in the natural world to low molecular weight, and then is finally decomposed by microorganisms into carbon dioxide and water. The mouth sheet 22 is a biodegradable nonwoven fabric made of polylactic acid. Note that the mouth sheet 22 may be made of various biodegradable nonwoven fabrics such as spunbond nonwoven fabric, air-through nonwoven fabric, or air-laid nonwoven fabric made of polylactic acid.

[0018] In the mask 1 according to this embodiment, the mouth sheet 22 is formed wider than the top sheet 20 and the filter sheet 21, and after the three sheets are laminated, the widthwise end of the mouth sheet 22 is folded toward the top sheet 20, and in an embossing process described below, the welded parts 9U and 9D are formed by embossing to fix the three sheets together. The nose fitter 7 is fixed between the folded mouth sheet 22 and the top sheet 20.

[0019] The mask body 2 is not limited to a three-layer laminate structure, and may be two layers or one layer. At least one of the top sheet 20 and the filter sheet 21 may be made of the above-mentioned various biodegradable nonwoven fabrics made of resins mainly composed of polylactic acid, or both the top sheet 20 and the filter sheet 21 may be made of the above-mentioned various biodegradable nonwoven fabrics made of resins mainly composed of polylactic acid.

[0020] For example, as a technique for forming pleats in the mask body, a method of folding the mask body into an Ω shape when viewed from the longitudinal direction (hereinafter referred to as "Ω folding") can be adopted. In Ω folding, the mask body continuous body is folded into an Ω shape along the shape of the sail by passing the mask body continuous body through a sail while conveying a mask body continuous body (hereinafter referred to as "mask body continuous body") formed by stacking sheet members in a certain direction, thereby forming pleats in the mask body continuous body.

[0021] When forming multiple pleats, the mask body continuum is folded at multiple locations, so it is possible to select a sheet material with a relatively low bending stiffness so that the mask body continuum follows the sailor's mold for folding at multiple locations. However, if the mask body is formed using a sheet material with a relatively low bending stiffness, the mask body cannot maintain its dome-shaped three-dimensional shape when the mask is worn, making it difficult to maintain a space between the mask body and the mouth. On the other hand, if the mask body is formed using a sheet material with a relatively high bending stiffness, the mask body continuum cannot follow the sailor's mold, and the size in the width direction after Ω folding deviates from the design value of the mask, and in the embossing process after the pleat forming process, the embossing is not performed to the width of the design value. This causes problems such as defective embossing. Also, if the tension of the mask body continuous body is adjusted too high so that the mask body continuous body follows the sailor's mold, the mask body continuous body will shrink in width, making it more difficult to adjust the size of the mask body. Also, although it is possible to adjust the bending stiffness and width shrinkage by increasing the basis weight of the sheet material forming the mask body, a large basis weight increases the airflow resistance of the mask body, impairing the comfort of wearing the mask.

[0022] Therefore, the mask manufacturing method according to the present embodiment provides a technique for suppressing deviation of the width direction size of the mask body continuous body from the design value in the pleat forming process without impairing the comfort of wearing the mask. The mask manufacturing method according to the present embodiment can suppress deviation of the size of the pleated nonwoven fabric sheet from the design value without impairing the comfort of wearing the mask.

[0023] Next, a method for manufacturing a mask according to the present embodiment will be specifically described. Fig. 4 is a flow chart showing an outline of the method for manufacturing a mask according to the present embodiment. In the method for manufacturing a mask according to the present embodiment, the steps before and after the step of forming pleats in a continuous mask body formed by laminating three layers of sheet members will be described.

[0024] In the mask manufacturing method according to the present embodiment, first, the tension of the mask body continuum is adjusted (step S101, an example of the "tension adjusting step" in the present application). The mask body continuum in the present embodiment is a base material in which three layers of sheets are stacked. Next, pleats are formed in the mask body continuum (step S102, an example of the "pleat forming step" in the present application). In the pleat forming step, a plurality of pleats are formed in the mask body continuum along the flow direction while the mask body continuum is transported in a certain direction. Next, the mask body continuum is embossed to fix the mask body continuum in which the three layers of sheets are stacked together (step S103, an example of the "embossing step" in the present application). In the embossing step, the mask body continuum is passed between an embossing roll and an anvil roll arranged opposite to the embossing roll, so that the mask body continuum is embossed. As a result, the three layers of sheets constituting the mask body continuum are fixed together, and in a later step, the mask body continuum is cut into one mask to form the mask body 2.

[0025] Next, the mask manufacturing method according to this embodiment will be described in more detail with reference to FIG. 5. FIG. 5 is a diagram showing an example of a mask manufacturing apparatus used in the mask manufacturing method according to this embodiment. This manufacturing apparatus M includes a roll device M1, a crease forming plate M2, a sailor M3 for Ω folding, and an embossing device M4. In this embodiment, the roll device M1, the crease forming plate M2, the sailor M3, and the embossing device M4 are arranged in this order from upstream to downstream in the conveying direction (MD direction). A mask body continuous body S formed by stacking three layers of sheets is sent out toward the roll device M1.

[0026] The roll device M1 has a first roll M11 arranged above the mask body continuous body S being transported, and a second roll (not shown) arranged below the mask body continuous body S. The first roll M11 and the second roll are arranged facing each other in the vertical direction with a gap provided through which the mask body continuous body S can pass. The first roll M11 and the second roll have their rotation axes in the CD direction, and rotate in opposite directions at the same speed while sandwiching the mask body continuous body S between the top and bottom, thereby sending out the mask body continuous body S to the crease forming plate M2 side. The manufacturing device M adjusts the tension of the mask body continuous body S in the transport direction by the roll device M1 and the embossing device M4 arranged downstream.

[0027] The mask body continuous body S that has passed through the roll device M1 is sent to the crease forming plate M2. The crease forming plate M2 has four plates extending in the conveying direction, and crease the mask body continuous body S from the skin side. The crease is formed in the valley fold of the Ω fold when viewed from the outside. The crease forming plate M2 is arranged so that the long sides of the plate face up and down, and by pressing the lower side downward on the conveyed mask body continuous body S, a crease is formed in the mask body continuous body S along the flow direction.

[0028] The mask body continuous body S that has passed through the crease forming plate M2 is sent to the sailor M3. FIG. 6 is a schematic diagram of the mask body continuous body S passing through the sailor M3, observed from the downstream side. The sailor M3 has a first plate M31 that is at the top and arranged with the center in the CD direction as the center in the left-right direction, a pair of second plates M32U, M32D that are arranged symmetrically with respect to the center in the CD direction below the first plate M31, a third plate M33 that is arranged below the second plates M32U, M32D with the center in the CD direction as the center in the left-right direction, and a pair of fourth plates M34U, M34D that are arranged symmetrically with respect to the center in the CD direction below the third plate M33. The mask body continuous body S passes along the six plates of the sailor M3, so that the mask body continuous body S is folded in the thickness direction. As a result, three pleats are formed in the mask body continuous body S.

[0029] The mask body continuous body S that has passed through the sailor M3 is sent to the embossing device M4. The embossing device M4 has an embossing roll M41 arranged above the mask body continuous body S being transported, and an anvil roll M42 arranged below the mask body continuous body S. The embossing roll M41 and the anvil roll M42 are arranged facing each other in the vertical direction with a gap provided so that the mask body continuous body S can pass through. The embossing roll M41 and the anvil roll M42 have their rotation axes in the CD direction, and form embossed parts that become the welded parts 9U and 9D shown in FIG. 2 in the mask body continuous body S. The embossing roll M41 and the anvil roll M42 rotate in opposite directions at the same speed to form embossed parts extending along the transport direction on the CD end side of the mask body continuous body S, while sending the mask body continuous body to the next process.

[0030] Here, by passing the mask body continuous body S along each plate of the sailor M3 as much as possible, it is possible to prevent the size of the mask body continuous body S having the pleats formed thereon from deviating from the design value. FIG. 7 is a diagram for explaining a mask manufacturing method according to a comparative example. 6 is a schematic diagram of the mask body continuous body S100 in the comparative example passing through the sailor M3 from the downstream side. As shown in FIG. 7, the mask body continuous body S100 does not follow each plate of the sailor, and the bending radius of the mask body continuous body S100 at the end of each plate of the sailor becomes larger than that of the present embodiment shown in FIG. 6, and the size in the width direction of the mask body continuous body S100 is smaller than the design value. In this way, if the size after folding the mask body continuous body becomes smaller than the design value of the mask in the pleat forming process, embossing is not performed at an appropriate position of the width direction end of the mask body continuous body in the embossing process for forming the welding parts 9U and 9D shown in FIG. 2, resulting in embossing failure. In this embodiment, the mouth sheet 22 is formed wider than the top sheet 20 and the filter sheet 21, and the width direction end of the nonwoven fabric sheet for the mouth sheet 22 is folded inward, and then embossing is performed to form the welding parts 9U and 9D. Therefore, in the pleat forming process, as long as the widthwise size of the nonwoven fabric sheet for the mouth sheet 22 does not deviate from the design value of the mask, the nonwoven fabric sheet can be folded back at an appropriate width and then embossed at the folded back portion of the nonwoven fabric sheet, thereby suppressing poor embossing.

[0031] As a result of intensive research, the inventors of the present application have found that, for example, by using a mouth sheet 22 with a width shrinkage rate of 2% or less as a mask material, it is possible to prevent the size of the mask body continuum S having pleats from deviating from the design value. The width shrinkage is measured in the following direction.

[0032] First, cut the nonwoven fabric sheet for the mouth sheet into a rectangle measuring 23 cm x 80 cm. Eight rectangular specimens are prepared. Next, chucks are attached to each end of the specimen, 5 cm from each end in the longitudinal direction. One chuck is fixed to the stand, and the other chuck is hung vertically downward. The width (W0) of the specimen at the center in the longitudinal direction is measured, and a load of 2.35 kg is applied to the lower chuck. This state is maintained for 30 seconds, and after 30 seconds, the width (W1) of the specimen at the center in the longitudinal direction is measured. The width shrinkage can be calculated using the following formula (1). (W0-W1) / W0×100(%) (1) In this embodiment, the width shrinkage was calculated for each of the eight samples, and the arithmetic average value was used as the measurement value of the width shrinkage of the nonwoven fabric sheet.

[0033] In addition, the inventors of the present application have found that, for example, the bending stiffness is 0.05 gf cm 2 / cm or more 0.2gf·cm 2 It was found that by using a mouth sheet 22 having a thickness of 1 / cm or less as a material for the mask, it is possible to prevent the size of the mask body continuum S having pleats from deviating from the design value. The bending stiffness was measured in the following directions.

[0034] First, the nonwoven fabric sheet for the mouth sheet is cut into a square shape of 20 cm x 20 cm, and eight square samples are prepared. Next, the bending stiffness is measured using a pure bending stiffness tester (KES-FB2-A) manufactured by Kato Tech Co., Ltd., with the direction of the sample corresponding to the conveying direction of the mask body continuum S as the bending axis. The bending stiffness of each of the eight samples is measured, and the arithmetic average of each bending stiffness is calculated by measuring each of the eight substrates. This calculation result is adopted as the measured value of the bending stiffness of the nonwoven fabric sheet. In addition, by using a mouth sheet 22 with a relatively high bending stiffness, it becomes easier for the mask body 2 to maintain a dome-shaped three-dimensional shape that bulges toward the non-skin side, and a space can be formed between the mask body 2 and the mouth.

[0035] The inventors of the present application also found that, for example, by adjusting the tension of the mask body continuous body S in the conveying direction before and after the pleat forming process by the sailor M3 to 0.5 N / cm or more and 4.0 N / cm, it is possible to suppress deviation of the size of the mask body continuous body S with the pleats formed thereon from the design value. The tension of the mask body continuous body S is adjusted between the roll device M1 and the embossing device M4. For example, the roll device M1 can adjust the tension by stretching the mask body continuous body S between the embossing device M4 while sending the mask body continuous body S downstream. By adjusting the tension of the mask body continuous body S, the mask body continuous body S can be aligned with each plate of the sailor M3 as shown in FIG. 6.

[0036] For the mouth sheet 22, a spunbond nonwoven fabric, an air-through nonwoven fabric, or an airlaid nonwoven fabric is used, but when a spunbond nonwoven fabric is used, its fiber diameter is preferably 1.5 denier or less. In all the examples and comparative examples shown in Fig. 8, which will be described next, a spunbond nonwoven fabric is used for the mouth sheet, a spunlace nonwoven fabric is used for the top sheet, and a meltblown nonwoven fabric is used for the filter sheet.

[0037] FIG. 8 is a table showing the numerical values ​​of the manufacturing method of a mask according to an example of this embodiment and the manufacturing method of a mask according to a comparative example. In FIG. 8, six examples, Examples 1 to 6, and eight comparative examples, Comparative Examples 1 to 8, are shown. In the "Resin" column, the raw material resin that is the main component of the mouth sheet is listed. In Examples 1 to 6, the mouth sheets are all nonwoven fabrics made from polylactic acid, in Comparative Examples 1 to 4, the mouth sheets are all nonwoven fabrics made from polypropylene, and in Comparative Examples 5 to 8, the mouth sheets are all nonwoven fabrics made from polylactic acid. In the "Weight per unit area" column, the weight per unit area (g / m2) of the nonwoven fabric sheet used in the mouth sheet is listed. 2 In this embodiment, the basis weight of the nonwoven fabric sheet is 20 to 40 g / m 2The "fiber diameter" column lists the fiber diameter (denier) of the nonwoven fabric sheet used in the mouth sheet. The fiber diameter of the nonwoven fabric sheet is preferably 1.5 denier or less. The "width shrinkage" column lists the percentage of width shrinkage of the nonwoven fabric sheet used in the mouth sheet. The percentage of shrinkage can be calculated using the method described above. The "Flexural stiffness" column shows the flexural stiffness (gf cm) of the nonwoven fabric sheet used in the mouth sheet. 2 The bending stiffness of the nonwoven fabric sheets in Examples 1 to 6 is 0.05 gf cm 2 / cm or more 0.2gf·cm 2 / cm or less. In the "Tension" column, the tension value of the mask body continuous body in the transport direction before and after the pleat forming process is shown. In Examples 1 to 6, the tension of the mask body continuous body in the transport direction is adjusted to 0.5 N / cm or more and 4.0 N / cm or less.

[0038] In the "Embossing failure" column, the occurrence or absence of embossing failure in the embossing process is recorded. In FIG. 8, the mark "◯" indicates the result where no embossing failure occurred, and the mark "×" indicates the result where an embossing failure occurred. As shown in FIG. 8, no embossing failure occurred in the masks according to Examples 1 to 6. On the other hand, embossing failure occurred in the comparative examples, except for Comparative Example 2. This embossing failure occurs because the width direction size of the widest nonwoven fabric sheet for the mouth sheet among the sheets constituting the mask body continuous body in the pleat forming process becomes smaller than the design value. In Comparative Examples 1, 3 to 5, and 8, the tension in the conveying direction of the mask body continuous body is set within the range of 0.5 N / cm to 4.0 N / cm, but the width shrinkage of the nonwoven fabric sheet exceeds 2% in Comparative Examples 1, 3, and 5, and the bending stiffness of the nonwoven fabric sheet is 0.05 gf·cm 2 / cm or more 0.2gf·cm 2 / cm or less, embossing failure could not be prevented even when the tension was adjusted to within the specified range. In Comparative Example 3, the fiber diameter was 2.1 denier, which is significantly greater than 1.5 denier, and the large fiber diameter caused a large width shrinkage of the nonwoven fabric sheet. In this example, the fiber diameter of the nonwoven fabric sheet was 1.5 denier or less, which was thin, so the width shrinkage of the nonwoven fabric sheet could be reduced. It is preferable that the fiber diameter of the nonwoven fabric sheet is 1.0 denier or more. In Comparative Examples 6 and 7, the width shrinkage of the nonwoven fabric sheet was 2% or less, and the bending stiffness was 0.05 gf·cm 2 / cm or more 0.2gf·cm 2 / cm or less, but since the tension in the transport direction of the mask body continuous body is outside the range of 0.5 N / cm or more and 4.0 N / cm or less, in the pleat forming process, the mask body continuous body does not fit along each plate of Sailor M3 as shown in Figure 7, the size of the nonwoven fabric sheet in the width direction becomes smaller, and embossing defects occur.

[0039] In Examples 1 to 6, the width shrinkage of the nonwoven fabric sheet was 2% or less, and the bending stiffness was 0.05 gf cm 2 / cm or more 0.2gf·cm 2 / cm or less, and the tension in the transport direction of the continuous mask body is in the range of 0.5 N / cm to 4.0 N / cm. Therefore, in the pleat forming process, the continuous mask body can be aligned with each plate of Sailor M3 as shown in Figure 6, and deviation in the size of the nonwoven fabric sheet in the width direction can be suppressed, thereby suppressing the occurrence of embossing defects.

[0040] The "Feel on Skin" column in Fig. 8 shows the results of a sensory test evaluating the feel on the skin when each mask was worn. In this sensory test, 30 evaluators were used, and in Fig. 8, "◯" indicates a result in which the feel on the skin was good, "△" indicates a result in which the feel on the skin was neither good nor bad, and "×" indicates a result in which the feel was poor. As shown in Fig. 8, the masks according to Examples 1 to 6 have a good feel on the skin.

[0041] The "Ease of breathing" column in FIG. 8 shows the results of a sensory test evaluating the ease of breathing when each mask was worn. In this sensory test, 30 evaluators were used, and in FIG. 8, the symbol "◯" indicates a result in which breathing was easy, the symbol "△" indicates a result in which breathing was neither easy nor difficult (ease of breathing was neither good nor bad), and the symbol "×" indicates a result in which breathing was difficult. Note that in this sensory test, the above-mentioned result indicated by the symbol "△" was not obtained. As shown in FIG. 8, the masks according to Examples 1 to 6 showed that breathing was easy. Note that in Comparative Example 2, no embossing defects occurred, but the basis weight of the nonwoven fabric sheet for the mouth sheet was 50 g / m 2 Since it is relatively large, I felt it was difficult to breathe when in use.

[0042] The "Airflow resistance" column in Figure 8 shows the airflow resistance (Pa / cm2) of the mask body for each mask. 2 The mask body of each mask is formed by laminating three layers of nonwoven fabric sheets as shown in FIG. 3. In the masks according to Examples 1 to 6, the airflow resistance is 50 Pa / cm 2 The air flow resistance is 50 Pa / cm 2 If the thickness is equal to or less than this, it is possible to prevent the wearer from feeling breathless when wearing the mask. Therefore, in Examples 1 to 6, it is possible to prevent the size of the pleated nonwoven fabric sheet from deviating from the design value without impairing the comfort of wearing the mask.

[0043] In addition, in Examples 1 to 6, it is possible to achieve both the bending rigidity required to secure a space between the mask body 2 and the mouth and the tension value of the mask body continuum that can follow each plate of Sailor M3. Also, in Examples 1 to 6, it is possible to suppress embossing defects caused by size deviation of the mask body continuum S in the embossing process after pleat formation, and by forming a space between the mask body 2 and the mouth, it is possible to stably manufacture masks that are comfortable to use.

[0044] By the above-described manufacturing method, a nonwoven fabric made of a polylactic acid resin can be manufactured. The raw material is polylactic acid, but the nonwoven fabric may contain monomers other than polylactic acid within a range that does not impair the effects of the present invention. Lactic acid includes optical isomers L-lactic acid and D-lactic acid, and the raw material in this embodiment is polylactic acid, which is a polymer of L-lactic acid. In the polylactic acid used as the raw material, the proportion of D-lactic acid is preferably 1% or less.

[0045] The features included in each of the embodiments and the modified examples thereof disclosed above can be combined with each other. [Explanation of symbols]

[0046] 1. Mask 2. Mask body 3, 4: Ear straps 5. Edge tape 6. Edge tape 7. Nose fitter 8. Pleats 15...Welding area 16...Welding area M··Manufacturing equipment M1··Roll device M2 ·· Folding plate M3··Sailor Roll M4··Embossing device S··Mask body continuum S100 Mask body continuum

Claims

1. A pleat forming process for forming a plurality of pleats along a conveying direction on a continuous mask body including a nonwoven fabric sheet made of fibers mainly composed of polylactic acid and having a width shrinkage rate of 2% or less; an embossing step of embossing the mask body continuous body on which the plurality of pleats are formed; A method for manufacturing a mask comprising:

2. The bending stiffness of the nonwoven fabric sheet is 0.05 gf cm ２ / cm or more 0.2gf・cm ２ / cm or less, A method for manufacturing the mask according to claim 1 .

3. The pleat forming step includes a tension adjusting step of adjusting the tension of the mask body continuous body in the transport direction to 0.5 N / cm or more and 4.0 N / cm or less. A method for manufacturing the mask according to claim 1 or 2.

4. In the pleat forming step, the plurality of pleats are formed by folding the mask body continuous body in a thickness direction. A method for manufacturing the mask according to claim 1 or 2.

5. The nonwoven fabric sheet is any one of a spunbond nonwoven fabric, an air-through nonwoven fabric, and an air-laid nonwoven fabric. A method for manufacturing the mask according to claim 1 or 2.

6. The nonwoven fabric sheet is a spunbond nonwoven fabric having a fiber diameter of 1.5 denier or less. A method for manufacturing the mask according to claim 5 .

7. The mask body continuous body is made of three layers of nonwoven fabric sheets laminated together, and has an airflow resistance of 50 Pa / cm ２ Below is the A method for manufacturing the mask according to claim 1 or 2.

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