Method for manufacturing a stretchable composite sheet

Abstract

To provide a method for manufacturing an elastic composite sheet that imparts elasticity and at the same time reduces yawing, etc. of seals and improves appearance.SOLUTION: A method for manufacturing an elastic composite sheet includes: a stretching step of forming an elastic sheet by feeding a raw material sheet between a pair of tooth groove rolls that engage with each other with respect to the raw material sheet including an elastic material and applying stretching processing; a shrinking step of shrinking the drawn elastic sheet to be brought into a weakened elongated state after the stretching step; and a sealing step of merging the elastic sheet with another sheet in the weakened elongated state and partially joining them to form a sealing section spaced apart in a conveying direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a stretchable composite sheet.

Background Art

[0002] Conventionally, a technique for manufacturing a composite sheet by joining a stretchable sheet and another sheet has been known. For example, Patent Document 1 describes a method for manufacturing a mask in which a first sheet serving as a mask body and a second sheet serving as ear loops are joined, and then the second sheet is stretched to impart stretchability. Patent Document 2 describes a method for manufacturing a composite sheet in which a second web that can be inelastically stretched is intermittently joined to at least one side of a first web having elastic stretchability. In this manufacturing method, after stretching the first web, the stretch is released and the first web is shrunk to remove permanent strain, and then the first web and the second web are joined at a plurality of dot-shaped embossed portions.

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Separate from the manufacturing methods described in Patent Documents 1 and 2, there is a method for manufacturing a stretchable composite sheet in which a stretchable sheet is conveyed while being stretched by the tension applied in the stretching step and intermittently sealed with another sheet. In this method, for example, another sheet can be bonded at a length corresponding to the elongation of the stretchable sheet, and the resulting stretchable composite sheet can be made more likely to exhibit stretchability. However, in the natural state after the release of the tension, the resulting stretchable composite sheet may have kinks, wrinkles, distortions, etc. in the sealed portions, and the appearance may be impaired. Patent Documents 1 and 2 do not describe such problems with the sealed portions.

[0005] In view of the above points, the present invention relates to a method for manufacturing a stretchable composite sheet that imparts stretchability while reducing kinks in the seal and improving the appearance.

Means for Solving the Problems

[0006] The present invention has a stretching step, and the stretching step is a step of supplying the raw material sheet containing the stretchable material between a pair of meshing tooth-groove rolls and performing stretching processing to form a stretchable sheet, after the stretching step, a shrinking step of shrinking the drawn stretchable sheet to a weakened stretched state, and a sealing step of joining the stretchable sheet in the weakened stretched state with another sheet and partially bonding them to form seal portions arranged at intervals in the conveying direction. A method for manufacturing a stretchable composite sheet having the above steps is provided.

Effects of the Invention

[0007] According to the method for manufacturing a stretchable composite sheet of the present invention, a stretchable composite sheet with reduced kinks in the seal and improved appearance can be suitably manufactured while imparting stretchability.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0009] A preferred embodiment of the method for manufacturing a stretchable composite sheet of the present invention will be described below with reference to the drawings.

[0010] The manufacturing method of the stretchable composite sheet of the present invention performs a [stretching step], a [shrinking step], and a [sealing step] in this order. In the [shrinking step], control is performed to weaken the degree of elongation of the stretchable sheet formed in the [stretching step] to an elongation state suitable for sealing in the [sealing step]. As a result, in the [sealing step], the stretchable sheet in the weakly elongated state is sealed with another sheet. As a result, the obtained stretchable composite sheet can reduce wrinkles and the like in the sealed portion in the natural state and can have a good appearance.

[0011] First, the [stretching step] will be described. The [stretching step] is typically a step of forming a stretchable sheet by supplying the raw material sheet containing the stretchable material between a pair of serrated rolls that mesh with each other and performing stretching processing on the raw material sheet. This [stretching step] can be performed by various commonly used mechanisms, and is preferably performed as follows. As shown in FIG. 1, a long strip-shaped raw material sheet 11 containing a stretchable material (hereinafter, also simply referred to as the raw material sheet 11) is unwound from the original roll 1 and continuously conveyed to a stretching mechanism 2 that performs the [stretching step]. The stretching direction of the stretchable material may be in one direction or in a plurality of directions, and includes at least the longitudinal direction Y of the raw material sheet 11, that is, the conveying direction Y in the manufacturing process. In the plane of the raw material sheet 11, the direction orthogonal to the longitudinal direction (conveying direction) Y is referred to as the width direction X. These various directions also apply to the stretchable sheet 12, another sheet 41, and the stretchable composite sheet 6 described later.

[0012] The stretching mechanism 2 has a first roll device 21 on the upstream side, a second roll device 23 on the downstream side, and a pair of serrated rolls 22A and 22B that mesh with each other and are arranged between the first roll device 21 and the second roll device 23. The first roll device 21 supplies the raw material sheet 11 between the pair of serrated rolls 22A and 22B. Stretching processing is performed on the raw material sheet 11 between the pair of serrated rolls 22A and 22B to form a stretchable sheet 12. The second roll device 23 pulls out the stretchable sheet 12 that has been subjected to stretching processing downstream. During the stretching process by the stretching mechanism 2, the conveying speed and / or tension of the raw material sheet 11 are controlled by the first roll device 21 and the second roll device 23. Thereby, a stretching force (an external force to stretch) is applied to the raw material sheet 11, and in this state, the raw material sheet 11 is subjected to a stretching process. Along with this, when the stretchable sheet 12 formed by the stretching process is pulled downstream by the second roll device 23, it is in a state of being stretched in the conveying direction (the longitudinal direction of the stretchable sheet 12) Y by the stretching force. The method of applying the stretching force will be described in detail below.

[0013] The upstream first roll device 21 has a configuration in which a pair of infeed rolls 21A and 21B are arranged to face each other in FIG. 1. The supply speed of the raw material sheet 11 between the grooved rolls 22A and 22B can be controlled by the roll peripheral speed V1 of the infeed rolls 21A and 21B. The downstream second roll device 23 has a configuration in which a pair of outfeed rolls 23A and 23B are arranged to face each other in FIG. 1. The feeding speed of the stretchable sheet 12 stretched between the grooved rolls 22A and 22B can be controlled by the roll peripheral speed V2 of the outfeed rolls 23A and 23B. By making the roll peripheral speed V2 of the outfeed rolls 23A and 23B faster than the roll peripheral speed V1 of the infeed rolls 21A and 21B (V2 > V1), a stretching force can be applied to the raw material sheet 11 and the stretchable sheet 12. That is, the stretching force can be controlled by appropriately setting the difference in the roll peripheral speeds (V2 - V1). Thereby, between the first roll device 21 and the second roll device 23, a stretching force in the conveying direction Y necessary for the stretching process can be suitably applied to the raw material sheet 11.

[0014] The configurations of the first roll device 21 and the second roll device 23 are not limited to those shown in FIG. 1. For example, at least one of the first roll device 21 and the second roll device 23 may have a configuration (not shown) in which a conveying roll and a dancer roll are combined. By the dancer roll, the tension on the raw material sheet 11 and the stretchable sheet 12 can be controlled, and the stretching force in the conveying direction Y required for stretching processing can be suitably applied to these sheets.

[0015] A drive device (not shown) is preferably connected to the first roll device 21 and the second roll device 23, and a control device (not shown) for centrally managing these drive devices is installed. By this control device, the conveying speed and the stretching force of the raw material sheet 11 can be set before the line operation, and these conveying speed and stretching force can be controlled during the line operation.

[0016] In the pair of grooved rolls 22A and 22B, stretching treatment is performed on the raw material sheet 11 to which the stretching force has been applied as described above. Specifically, by meshing and rotating the teeth arranged on the peripheral surfaces of the grooved rolls 22A and 22B with each other, the raw material sheet 11 between the teeth of the meshed grooved roll 22A and the teeth of the grooved roll 22B is stretched. Thereby, a stretchable sheet 12 in which the stretchability of the stretchable material contained in the raw material sheet 11 is more strongly exhibited is formed. The processing using such grooved rolls 22A and 22B can be performed, for example, by the methods described in paragraphs

[0012] to

[0040] of JP-A-2007-177384 and paragraphs

[0055] to

[0085] of JP-A-2008-179128.

[0017] In FIG. 1, the teeth of each of the tooth groove rolls 22A and 22B have a length extending in the roll axis direction and are arranged at intervals in the roll circumferential surface direction. However, the tooth arrangement is not limited to this form. For example, the teeth may have a length extending in the roll circumferential direction and be arranged at intervals in the roll axis direction. Further, the teeth may be continuous in the extending direction, or may be divided into a plurality along the extending direction. However, from the viewpoint of imparting stretchability in the longitudinal direction Y of the raw material sheet 11, it is preferable that the teeth of each of the tooth groove rolls 22A and 22B have a length extending in the roll circumferential direction and are arranged at intervals in the roll axis direction.

[0018] It is preferable that a driving device (not shown) is connected to at least one of the rotation axes of the pair of tooth groove rolls 22A and 22B. The driving device is preferably managed integrally with the driving devices connected to the first roll device 21 and the second roll device 23 by the above-described control device.

[0019] The raw material sheet 11 to be subjected to such stretching is as described above and includes a stretchable material, may be composed only of a stretchable material, or may include a stretchable material and a non-stretchable material. In particular, when the raw material sheet 11 includes a stretchable material and a non-stretchable material, the non-stretchable material is stretched by the above-described stretching to reduce the resistance of the stretchable material's stretchability, and a stretchable sheet 12 with high strength and high stretchability can be preferably formed. The "stretchability" of the stretchable material referred to here means the property that a material with a length of 100 is stretched to a length of 150 by applying a force in one direction and then contracts to a length of 100 or more and 110 or less by removing the force. The "non-stretchability" of the non-stretchable material means the property that it cannot be stretched to a length of 150, or even if it can be stretched, it does not contract to a length of 100 or more and 110 or less when the force is removed.

[0020] The raw material sheet 11 may be a single-layer sheet or a multi-layer laminated sheet. Examples of the single-layer sheet include a sheet obtained by blending elastic fibers and inelastic fibers. Examples of the laminated sheet include a sheet obtained by laminating and joining an inelastic layer containing inelastic fibers on one or both sides of an elastic layer containing elastic fibers. The elastic layer and the inelastic layer are preferably fiber layers such as non-woven fabrics. Further, the elastic layer may be a film-like layer or a net-like layer having elasticity instead of the fiber layer. Another example of the laminated sheet is a sheet in which a plurality of elastic filaments are arranged between a pair of inelastic layers so as to extend in the longitudinal direction (transport direction) Y of the sheet without crossing each other. Here, the "elasticity" and "inelasticity" mentioned herein are synonymous with the definitions of the above-mentioned "stretchability" and "non-stretchability". The stretchable material contained in the raw material sheet 11 can be such elastic fibers, elastic layers, and elastic filaments.

[0021] The elastic fibers are preferably made of an elastic material. Examples of the elastic material include thermoplastic elastomers, rubbers, ethylene-propylene copolymers, etc. Among these, thermoplastic elastomers are preferred in terms of relatively easily forming fibrous elastic bodies. Examples of thermoplastic elastomers include polyurethanes, styrene-based (SBS, SIS, SEBS, SEPS, etc.), olefin-based (copolymers of ethylene, propylene, butene, etc.), vinyl chloride-based, polyester-based, etc. These can be used alone or in combination of two or more.

[0022] In the elastic layer containing the elastic fibers, the content of the elastic fibers in the elastic layer is preferably 50% by mass or more and 100% by mass or less, and more preferably 75% by mass or more and 100% by mass or less. The elastic resin forming the elastic fibers of the elastic layer can also contain inelastic resins such as polyethylene, polypropylene, polyester (polyethylene terephthalate and polybutylene terephthalate), nylon, organic or inorganic pigments, and various additives (antioxidants, plasticizers, etc.). Further, the first fiber layer can contain inelastic fibers, organic or inorganic pigments. When the elastic layer is in the form of a film or a net, the above-mentioned various elastic resins can be used as the material for forming the film or the net.

[0023] Examples of the inelastic fiber include fibers made of polyethylene, polypropylene, polyester (such as polyethylene terephthalate and polybutylene terephthalate), nylon, and biodegradable resins such as polylactic acid. In the inelastic layer containing the inelastic fiber, the constituent fibers may be short fibers or long fibers, and may be hydrophilic or water-repellent. Also, core-sheath composite fibers, split fibers, profiled cross-section fibers, crimped fibers, heat-shrinkable fibers, etc. can be used. These fibers can be used alone or in combination of two or more.

[0024] The inelastic layer containing the inelastic fiber is preferably stretchable. The "stretchable" as used herein includes (a) the case where the constituent fibers themselves stretch, and (b) the case where even if the constituent fibers themselves do not stretch, the fibers joined at the intersections separate from each other, or the three-dimensional structure formed by a plurality of fibers due to the joining of fibers or the like changes structurally, or the constituent fibers are torn, or the sag of the fibers is stretched, so that the entire inelastic layer stretches. The inelastic layer may already be stretchable in the state before the above-mentioned stretching process. Alternatively, it may not be stretchable in the state before the stretching process, but may become stretchable after the stretching process is performed. From the viewpoint of improving the transportability of the raw material sheet containing the inelastic layer, it is preferable that the inelastic layer is not stretchable in the state before the stretching process.

[0025] The elastic filament can be a filamentous synthetic rubber or natural rubber. Alternatively, it can be obtained by dry spinning (melt spinning) or wet spinning. It is preferable that the elastic filament is obtained directly by melt spinning without winding it up once. The elastic filament is preferably obtained by stretching an unstretched yarn. It is preferable that the elastic filament is formed by stretching an elastic resin in a molten or softened state. Thereby, the elastic filament can be accurately joined to the inelastic layer in a non-stretched state. The stretching process when using such an elastic filament can be performed by the method described in paragraphs

[0055] to

[0085] of the aforementioned Japanese Patent Application Laid-Open No. 2008-179128.

[0026] Separate from the elastic layer and the inelastic layer, a fine fiber layer composed of ultra-fine fibers having an average fiber diameter of 50 nm or more and 2000 nm or less may be included. Such a fine fiber layer becomes a filter layer having high collectability for fine particles in the outside air in various sheet products. For example, when the stretchable composite sheet obtained by the method for producing a stretchable composite sheet of the present invention is applied to a mask, the fine fiber layer can collect pollen, droplets, etc. having a particle diameter of 3 μm or more and 5 μm or less, and can enhance the defensive ability against the intake of these fine particles into the body and the defensive ability against scattering into the outside air. The average fiber diameter of the fine fiber layer is preferably 1000 nm or less, more preferably 100 nm or more, and still more preferably 200 nm or more. This fine fiber layer can be produced, for example, by an electrospinning method. From the viewpoint of maintaining the function as a filter layer, it is preferable that the fine fiber layer is inside the outermost surfaces of the front and back of the raw material sheet 11 in the layer structure of the inelastic layer. In this case, various non-woven fabrics are preferable as the layer covering the fine fiber layer as a protective layer with a good texture. Among non-woven fabrics, from the viewpoint of strength, a non-woven fabric obtained by the spunbond method (spunbond non-woven fabric) or a non-woven fabric produced by the needle punch method (needle punch non-woven fabric) is more preferable, and a spunbond non-woven fabric is still more preferable. Also, from the viewpoint of maintaining the function as a filter layer, it is preferable that another fiber layer is interposed between the fine fiber layer and the aforementioned elastic layer. For example, a laminated structure in which an inelastic layer is disposed outside the aforementioned elastic layer, and further, a fine fiber layer and a protective layer are disposed outside thereof can be mentioned. Such a laminated structure may be on both sides or one side of the elastic layer. Such a fine fiber layer or a laminate of the fine fiber layer and the protective layer may be laminated on the raw material sheet 11 before the [stretching process], or may be laminated after the [stretching process] and before the [sealing process] described later. Hereinafter, when referring to the stretchable sheet 12, the form in which this fine fiber layer or a laminate of the fine fiber layer and the protective layer is laminated is also included.

[0027] The stretchable sheet 12 imparted with high stretchability by the above [stretching process] is in a state of being strongly stretched in the conveying direction (strong stretching state) at the stage of being pulled out by the second roll device 23. For example, although it depends on the material of the raw material sheet 11 and the stretching ratio, the stretchable sheet 12 pulled out by the second roll device 23 of the stretching mechanism 2 may be in a state of being stretched up to about twice the length in the conveying direction in the natural state without applying a tensile load.

[0028] After the above [stretching process], a [shrinking process] and a [sealing process] are performed. The [shrinking process] will be described. The stretchable sheet 12 formed by the stretching process is pulled out by the second roll device 23 of the stretching mechanism 2 and continuously conveyed to the shrinking mechanism 3 that performs the [shrinking process]. The shrinking mechanism 3 is a mechanism that weakens the stretching force applied to the stretchable sheet 12 in the above [stretching process] to an appropriate degree for sealing in the [sealing process] and shrinks the stretched stretchable sheet 12. That is, it is a mechanism that shrinks the stretchable sheet 12 to a weakened stretched state. The above-mentioned weakened stretched state means a stretched state weaker than the stretched state (strong stretching state) immediately after the stretchable sheet 12 is pulled out by the second roll device 23 of the [stretching process] and stretched more than the natural state in which the stretching force is released. The contraction mechanism 3 is, for example, as shown in FIG. 1, a mechanism that combines the upstream first nip roll device 31 and the downstream second nip roll device 32. The nip rolls are typically rolls with a smooth surface. The first nip roll device 31 feeds the stretchable sheet 12 between both rolls to the second nip roll device 32 by the rotation of a pair of opposed nip rolls 31A and 31B. The second nip roll device 32 further feeds the stretchable sheet 12 between both rolls downstream by the rotation of a pair of opposed nip rolls 32A and 32B. In the contraction mechanism 3, the roll peripheral speed V4 of the nip rolls 32A and 32B in the downstream second nip roll device 32 is made slower than the roll peripheral speed V3 of the nip rolls 31A and 31B in the upstream first nip roll device 31 (V3 > V4). At this time, the roll peripheral speed V4 of the nip rolls 32A and 32B in the second nip roll device 32 is preferably made slower than the roll peripheral speed V2 of the outfeed rolls 23A and 23B in the second roll device 23 in the stretching process. Thereby, it is easy to enhance the effect of the contraction conveyance. By controlling the roll peripheral speed of each roll in this way, the conveyance speed of the stretchable sheet 12 in the contraction mechanism 3 can be made slower than the conveyance speed of the stretchable sheet 12 in the stretching mechanism 2. Thereby, the stretching force applied to the stretchable sheet 12 is weakened, and the stretchable sheet 12 is contracted to a weakened stretched state. That is, the strongly stretched state of the stretchable sheet 12 immediately after [stretching process] is changed to a weakly stretched state. The contraction may occur in either the length in the longitudinal direction (conveyance direction) Y of the stretchable sheet 12 or the length in the width direction X orthogonal to the longitudinal direction Y, or both. In the [contraction process], as described above, by setting the roll peripheral speed (V3 - V4), the stretchable sheet 12 can be suitably controlled to a weakened stretched state (weakly stretched state) suitable for sealing in the [sealing process]. This weakened stretched state (weakly stretched state) can be appropriately set according to the sealing conditions in the subsequent [sealing process] and the material of another sheet to be sealed, etc., so as to perform the seal formation well and improve the appearance of the seal portion.

[0029] It is preferable that the first nip roll device 31 and the downstream second nip roll device 32 are connected to a drive device (not shown) on the rotating shaft. The drive device is preferably managed centrally by the above-described control device together with the drive devices connected to the first roll device 21 and the second roll device 23.

[0030] In the [Shrinking Step], when the elongation rate of the stretchable sheet 12 immediately after the [Stretching Step] is set to 1.00 times, it is preferable that the elongation rate of the stretchable sheet 12 immediately after the [Shrinking Step] (hereinafter also referred to as the elongation rate after shrinking) is shrunk to 0.84 times or less. This elongation rate after shrinking, in other words, means the ratio of the length of the stretchable sheet 12 after the shrinking process in the [Shrinking Step] to the length of the stretchable sheet 12 in the stretched state immediately after the [Stretching Step]. As shown in FIGS. 2(A) and (B), the requirement for the elongation rate after shrinking described above is preferably satisfied in at least one of the length in the longitudinal direction (transport direction) Y and the length in the width direction X of the stretchable sheet 12. FIG. 2(A) shows that the length L0 in the longitudinal direction (transport direction) Y of the stretchable sheet 12 becomes the length L1 after the shrinking process. It is preferable that the ratio (L1 / L0) of the length L1 to the length L0 shown here is 0.84 or less. FIG. 2(B) shows that the length W0 in the width direction X of the stretchable sheet 12 becomes the length W1 after the shrinking process. It is preferable that the ratio (W1 / W0) of the length W1 to the length W0 shown here is 0.84 or less.

[0031] By satisfying the requirement that the elongation rate after shrinking is 0.84 times or less, the appearance of the sealed portion of the stretchable composite sheet obtained through the [Sealing Step] described later becomes better. From this viewpoint, the elongation rate after shrinking is preferably 0.79 times or less, and more preferably 0.69 times or less. Also, the stretchable sheet 12 immediately after the [Shrinking Step] preferably has an elongation rate (the ratio of the length immediately after the [Shrinking Step] to the length in the natural state) of 0.59 times or more in at least one of the longitudinal direction Y and the width direction X with respect to the length in the natural state.

[0032] (Method for Measuring the Elongation Rate after Shrinking in the [Shrinking Step]) Mark the sheet in the stretched state immediately after the stretching process at intervals of 100 mm, and measure the interval between the marks made at the 100 mm intervals in the sheet in the shrunk state immediately after the shrinking process. Elongation rate = L mm (sheet in the shrunk state immediately after the shrinking process) / 100 mm (sheet in the stretched state immediately after the stretching process)

[0033] Next, the [sealing process] will be described. In the [sealing process], the stretchable sheet 12 is put into the aforementioned weakened stretched state (weakly stretched state) and merged with another sheet 41 (also simply referred to as sheet 41). Although the sheet 41 is shown as being unwound from the raw material roll 4 in FIG. 1, it is not limited thereto, and it may be conveyed to the merging point through various processing steps. Supply the merged stretchable sheet 12 and sheet 41 between the sealing device 51 and the anvil roll 52 that constitute the sealing mechanism 5, and seal them partially. By this sealing, seal portions 61 (see FIG. 3 for example) arranged at intervals in the conveyance direction Y are formed, and a stretchable composite sheet 6 integrated by the seal portions 61 is obtained. As described above, by interposing the [shrinking process] between the [stretching process] and the [sealing process], the seal portions 61 are formed in a state where the degree of elongation of the stretchable sheet 12 does not become excessive. As a result, the obtained stretchable composite sheet 6 has high stretchability, and at the same time, even when the stretched state is released and it contracts to the natural state, the occurrence of sagging, wrinkles, etc. in the seal portions 61 is suppressed, and the appearance is good.

[0034] The [sealing process] can be performed by various means commonly used in the production of this type of stretchable composite sheet. For example, the [sealing process] may be performed by ultrasonic welding, by thermal welding, or by applying a hot melt type adhesive. Among them, from the viewpoints of appearance and safety, it is preferable to perform the [sealing process] by ultrasonic welding.

[0035] The sheet 41 may be joined not only at the joining position shown in FIG. 1, but also upstream of the [sealing step]. For example, the sheet 41 may be joined to the raw material sheet 11 upstream of the [stretching step] and laminated, and then the above-mentioned [stretching step] and [shrinking step] may be performed. Further, the sheet 41 may be joined to the stretchable sheet 12 immediately after the above-mentioned [stretching step], during the [shrinking step], or between the [shrinking step] and the [sealing step].

[0036] As such a sheet 41, various sheets that can be sealed to the stretchable sheet 12 can be used without particular limitation. For example, it may be the above-mentioned non-stretchable sheet including the non-elastic layer, or it may be the same as the stretchable sheet 12. Further, the sheet 41 may include the above-mentioned fine fiber layer, or a laminate of the fine fiber layer and the protective layer, similar to the stretchable sheet 12. When the sheet 41 is the same as the stretchable sheet 12 and the joining is after the [shrinking step], it is preferable that the sheet 41 has been subjected to the same steps as the above-mentioned [stretching step] and [shrinking step] up to the joining and has become a stretchable sheet. Further, when the sheet 41 to be joined is the same as the stretchable sheet 12 including the above-mentioned fine fiber layer, or a laminate of the fine fiber layer and the protective layer, and the joining is after the [shrinking step], the fine fiber layer, or the laminate of the fine fiber layer and the protective layer may be laminated before the [stretching step], or may be laminated after the [stretching step], similar to the stretchable sheet 12.

[0037] Each seal portion 61 formed in the [sealing step] can be in various forms of continuous linear or strip-shaped. For example, as shown in FIG. 3, there are linear or strip-shaped ones that are continuous in a direction intersecting the longitudinal direction Y, which is the stretching direction of the stretchable sheet 12. The intersecting direction can be various, for example, the width direction X. The outer shape of such a continuous linear or strip-shaped seal portion 61 can be various, for example, an arc shape. Further, the seal portion 61 may be in a form that is entirely continuous, or may be in a form that is separated into a plurality along the continuous direction and arranged intermittently. Further, in the seal portion 61 having a strip-like predetermined width, the entire area of the strip region may be joined, or a portion (joined portion) for joining the sheets and a portion (non-joined portion) not joined may be mixed. Since various forms of such mixing can be taken, for example, in the strip-like seal portion, the joined portions are arranged in a mesh pattern, and an island-like portion between the mesh-like joined portions is a non-joined portion. When the seal portion 61 has such a mixed region of a joined portion and a non-joined portion in this way, the rigidity is reduced while the seal strength of the seal portion 61 is maintained. Thereby, the touch feeling of the seal portion 61 can be made soft. On the other hand, when the seal portion 61 has such a mixed region and the rigidity is reduced, stress concentration due to shrinkage is likely to occur. However, in the manufacturing method of the stretchable composite sheet of the present invention, since the above-described [stretching step], [shrinking step], and [sealing step] are performed in this order, the stress associated with shrinkage is reduced in the [sealing step], and the occurrence of sagging, wrinkles, distortion, etc. in the seal portion 61 is reduced.

[0038] Furthermore, each seal portion 61 formed in the [sealing step] preferably has an inclined portion continuous for 1 mm or more in a direction intersecting the stretching direction of the stretchable sheet 12 in a plan view of the stretchable sheet 12. The stretching direction is the direction in which the stretchable sheet 12 is stretched after the [stretching step], and coincides with the longitudinal direction Y of the stretchable sheet 12, that is, the conveyance direction Y. The presence of the inclined portion 62 makes the effect of the shrinking step remarkable and is preferable. Also, the continuous length of the inclined portion 62 is realistically 83 mm or less. In the natural state of the stretchable composite sheet 6 obtained by forming such a seal portion 61, the inclined portion 62 is in a direction intersecting the direction in which the stretching force is released and the sheet shrinks. Stress concentration due to shrinkage is likely to occur in such an inclined portion 62. However, in the manufacturing method of the stretchable composite sheet of the present invention, since the above-described [stretching step], [shrinking step], and [sealing step] are performed in this order, the stress associated with shrinkage is reduced in the [sealing step], and the occurrence of sagging, wrinkles, distortion, etc. in the seal portion 61 is reduced.

[0039] The intersecting direction means that the intersection angle with the elongation direction (longitudinal direction Y) is more than 0°. The intersecting direction is preferably a direction intersecting both the elongation direction (longitudinal direction Y) and the width direction X, that is, an oblique direction.

[0040] Such an inclined portion 62 may be present in the entire sealing portion 61 or may be present in a part thereof. Further, the inclined portion 62 may be a straight line as shown in FIG. 4(A), or may be a curve as shown in FIGS. 4(B) and 4(C). When the inclined portion 62 is a curve, it is determined as an oblique portion if the tangent line at any point on the curve intersects the width direction X and the longitudinal direction Y. The length of the inclined portion 62 is the sealing length of the inclined portion 62.

[0041] As described above, according to the manufacturing method of the stretchable composite sheet of the present invention, it is possible to suitably manufacture a stretchable composite sheet that imparts high stretchability, reduces seal sag, etc., and improves the appearance.

[0042] Further, in the manufacturing method of the stretchable composite sheet of the present invention, as shown in FIG. 5, it is preferable to have a step ([elongation suppression step]) of performing a process for suppressing the elongation behavior on the stretchable sheet 12 between the [shrinkage step] and the [sealing step]. This process for suppressing the elongation behavior is a process for suppressing the elongation behavior due to an unintentional external force or the like accompanying the conveyance of the stretchable sheet 12, and is a process for maintaining the weakly stretched state controlled in the [shrinkage step]. Thereby, even if an external force is applied during the conveyance after the [shrinkage step], it is possible to prevent the stretchable sheet 12 from elongating more than necessary. The elongation suppression mechanism 7 that performs the [elongation suppression step] is composed of sealing rolls 7A and 7B arranged opposite to each other in FIG. 5. The sealing rolls 7A and 7B continuously seal the end portions (both sides in the longitudinal direction Y) 12E and 12E in the width direction X of the stretchable sheet 12 along the longitudinal direction Y as shown in FIG. 6. Thereby, the shrinkage state of the stretchable sheet 12 set in the above-described [shrinkage step] is maintained, and the stretchable sheet 12 is prevented from elongating further during the subsequent conveyance. Thereby, the sealing portion 61 in the [sealing step] can be formed better.

[0043] The end portions 12E, 12E in the width direction X (both sides in the longitudinal direction Y) of the stretchable sheet 12 are blank portions that are not incorporated into the subsequent product and are outside the region where the seal portion 61 is formed. Therefore, the stretchable composite sheet 6 to be manufactured does not include the end portions 12E subjected to the above-described stretch behavior suppression process, and the stretchability of the stretchable composite sheet 6 can be sufficiently exhibited. From the viewpoint that the wider the width is, the greater the suppression effect is, the length in the width direction X of each end portion 12E is preferably 2.5% or more of the length in the width direction X of the stretchable sheet 12, and realistically 18% or less.

[0044] The [elongation suppression step] is not limited to the above-described continuous seal process. Various processes for suppressing the elongation behavior of the end portions 12E, 12E in the width direction X (both sides in the longitudinal direction Y) of the stretchable sheet 12 can be performed. For example, a process of fusing the end portions 12E, 12E with hot air or a process of applying an adhesive such as a hot melt type adhesive and bonding them may be used, or a process of sandwiching and fixing the end portions 12E, 12E with a belt or the like may be used.

[0045] This [elongation suppression step] is not limited to the case of being performed on the stretchable sheet 12 alone, and may be performed on a laminated sheet in which the stretchable sheet 12 and the sheet 41 are joined together as shown in FIG. 5. By performing the [elongation suppression step] on the laminated sheet of the stretchable sheet 12 and the sheet 41, the subsequent [sealing step] can be made better. In particular, when the joining sheet 41 is the same as the stretchable sheet 12, the stretchable sheet 12 and the sheet 41 can be brought into a similar elongation suppression state, and the subsequent [sealing step] can be performed better.

[0046] The stretchable composite sheet 6 obtained by the method for manufacturing a stretchable composite sheet of the present invention can be applied to various articles. Examples of the articles include sheet products. The stretchable composite sheet 6 can be cut to a size corresponding to the sheet product and, if necessary, bonded to other members to manufacture the sheet product. Examples of the sheet product include masks, disposable absorbent articles, clothing, and the like. Among them, the obtained stretchable composite sheet 6 is preferably applied to a mask. The stretchable composite sheet 6 is preferably the outermost layer of the sheet product, for example, the outermost layer of a mask.

[0047] When applying the stretchable composite sheet 6 to a mask, the same stretchable sheet 12 as the other sheet 41 described above is used. In the method for manufacturing a mask, the mask is manufactured through a step of cutting the stretchable composite sheet 6 provided with the seal portion 61 into a mask shape. The method for manufacturing this mask will be described with reference to FIGS. 7(A) to (C). In FIGS. 7(A) and 7(B), the two sheets are shown slightly separated from each other so that the overlapping state of the stretchable sheet 12 and the other sheet 41 can be recognized, but in actuality, they are laminated without separation.

[0048] First, as shown in FIG. 7(A), in the above-mentioned [sealing step], the seal portion 61 is formed on the stretchable composite sheet 6. The seal portion 61 is located at the left and right centers of the mask body portion of the mask to be manufactured in the mask planned region 63, and corresponds to the portion that abuts on the region connecting the wearer's nose, mouth, and chin. That is, the seal portion 61 forms the nose-chin line of the mask. The seal portion 61 is preferably formed in an arc shape in the width direction X of the stretchable composite sheet 6. Next, as shown in FIG. 7(B), the outer shapes of the mask body 81 and the ear loops 82 are cut out toward the rear in the longitudinal direction Y from the seal portion 61. At this time, in the ear loops 82, an opening 83 for passing the ear is further opened. Thereby, the mask 8 shown in FIG. 7(C) is manufactured. The mask 8 shown in FIG. 7(C) is in a state of being folded in half at the position of the seal portion 61.

[0049] In the method for manufacturing the mask described above, the mask 8 obtained is not limited to a form in which the mask body 81 and the ear-hanging part 82 are integrated. For example, it is also possible to manufacture a mask in a form in which only the mask body 81 is cut and an ear-hanging part of a separate member is joined to the obtained mask body 81.

[0050] The mask 8 manufactured in this way has high stretchability from the nose-jaw line toward the ear side, resulting in high wearing fit and followability. At the same time, in the manufactured mask 8, wrinkles in the nose-jaw line are reduced, the line of the seal part 61 in the wearing state is neatly maintained, and the appearance is good.

[0051] Regarding the above-described embodiments, the present invention further discloses the following methods for manufacturing a stretchable composite sheet and a mask.

[0052] <1> Having a stretching step, the stretching step is a step of supplying the raw material sheet containing the stretchable material between a pair of serrated rolls that mesh with each other and performing stretching processing to form a stretchable sheet, after the stretching step, a shrinking step of shrinking the drawn stretchable sheet to a weakened stretched state, and a sealing step of joining the stretchable sheet in the weakened stretched state to another sheet and partially joining them to form seal parts arranged at intervals in the conveying direction, A method for manufacturing a stretchable composite sheet having the above steps.

[0053] <2> In the shrinking step, when the elongation rate of the stretchable sheet immediately after the stretching step is set to 1.00 times, the elongation rate of the stretchable sheet immediately after the shrinking step is shrunk to 0.84 times or less, and the elongation rate is preferably 0.69 times. The method for manufacturing a stretchable composite sheet according to <1> above. <3> In the sealing step, welding is performed by ultrasonic waves. The method for manufacturing a stretchable composite sheet according to <1> or <2> above. <4> Each seal portion formed in the sealing step has an inclined portion that is continuous for 1 mm or more in a direction intersecting the stretching direction of the stretchable sheet in a plan view of the stretchable sheet, and the continuous length of the inclined portion is preferably 83 mm or less. The method for manufacturing a stretchable composite sheet according to any one of <1> to <3>. <5> The method for manufacturing a stretchable composite sheet according to any one of <1> to <4>, which includes a step of performing a process for suppressing the stretching behavior on the stretchable sheet between the shrinking step and the sealing step.

[0054] <6> The stretching direction of the stretchable material includes at least the longitudinal direction of the raw material sheet, that is, the conveyance direction in the manufacturing process. The method for manufacturing a stretchable composite sheet according to any one of <1> to <5>.

[0055] <7> The stretching step is Controlling the conveyance speed and / or tension of the raw material sheet by a first roll device on the upstream side and a second roll device on the downstream side with respect to the raw material sheet, and applying an elongation force in the conveyance direction to the raw material sheet. Supplying the raw material sheet between a pair of meshing grooved rolls arranged between the first roll device and the second roll device by the first roll device, and performing stretching processing to form a stretchable sheet. The step of pulling out the stretchable sheet downstream in a state where the stretchable sheet is stretched in the conveyance direction by the elongation force by the second roll device. The method for manufacturing a stretchable composite sheet according to any one of <1> to <6>. <8> The first roll device has a configuration in which a pair of infeed rolls are arranged opposite to each other, the second roll device has a configuration in which a pair of outfeed rolls are arranged opposite to each other, and by making the roll peripheral speed V2 of the outfeed roll faster than the roll peripheral speed V1 of the infeed roll (V2 > V1), an elongation force is applied to the raw material sheet and the stretchable sheet. The method for manufacturing a stretchable composite sheet according to <7>. <9> The manufacturing method of the stretchable composite sheet according to <7> or <8>, wherein at least one of the first roll device and the second roll device has a configuration combining a conveying roll and a dancer roll. <10> The manufacturing method of the stretchable composite sheet according to any one of <7> to <9>, wherein a drive device is connected to the first roll device and the second roll device, and a control device for centrally managing these drive devices is installed. <11> The manufacturing method of the stretchable composite sheet according to any one of <7> to <10>, wherein the stretchable sheet drawn out by the second roll device is in a state of being stretched up to twice the length in the conveying direction in a natural state without applying a tensile load. <12> The manufacturing method of the stretchable composite sheet according to any one of <7> to <11>, wherein the weakened stretched state means a stretched state weaker than the stretched state immediately after the stretchable sheet is drawn out by the second roll device in the stretching step, and is in a state of being stretched more than the natural state in which the stretching force is released.

[0056] <13> The manufacturing method of the stretchable composite sheet according to any one of <1> to <12>, wherein the raw material sheet contains the stretchable material and the non-stretchable material. <14> Regarding the "stretchability" of the stretchable material, it means the property that a material with a length of 100 is stretched to a length of 150 by applying a force in one direction and then contracts to a length of 100 or more and 110 or less by removing the force. Regarding the "non-stretchability" of the non-stretchable material, it means the property that it cannot be stretched to a length of 150 or, even if it can be stretched, it does not contract to a length of 100 or more and 110 or less when the force is removed. The manufacturing method of the stretchable composite sheet according to <13>. <15> The manufacturing method of the stretchable composite sheet according to any one of <1> to <14>, wherein the raw material sheet is formed by arranging a plurality of elastic filaments between a pair of non-elastic layers without intersecting each other and extending in the longitudinal direction of the sheet, that is, the conveying direction.

[0057] <16> The shrinking mechanism for performing the shrinking step has a mechanism combining a first nip roll device on the upstream side and a second nip roll device on the downstream side, and the roll peripheral speed V4 of the nip roll in the second nip roll device on the downstream side is made slower than the roll peripheral speed V3 of the nip roll in the first nip roll device on the upstream side. The method for manufacturing a stretchable composite sheet according to any one of <1> to <15>. <17> The nip roll is a roll having a smooth surface. The method for manufacturing a stretchable composite sheet according to <16>. <18> The roll peripheral speed V4 of the nip roll in the second nip roll device is made slower than the roll peripheral speed V2 of the outfeed roll in the second roll device. The method for manufacturing a stretchable composite sheet according to <16> or <17>. <19> The stretchable sheet immediately after the shrinking step has an elongation rate of 0.59 times or more with respect to the length in the natural state in at least one of the longitudinal direction and the width direction. The method for manufacturing a stretchable composite sheet according to any one of <1> to <18>.

[0058] <20> Each seal portion formed in the sealing step is continuous in a linear or strip shape. The method for manufacturing a stretchable composite sheet according to <4>. <21> The intersecting direction of the inclined portion means that the intersection angle with the stretching direction of the stretchable sheet is more than 0°, and the intersecting direction is preferably a direction intersecting both the stretching direction and the width direction, that is, an oblique direction. The method for manufacturing a stretchable composite sheet according to <20>.

[0059] <22> Between the shrinkage step and the sealing step, there is an elongation suppression step of performing processing for suppressing the elongation behavior on the stretchable sheet. The elongation suppression mechanism for performing the elongation suppression step consists of sealing rolls arranged opposite to each other. The sealing rolls perform continuous sealing along the longitudinal direction on the end portions in the width direction of the stretchable sheet. The method for manufacturing a stretchable composite sheet according to any one of <1> to <21>. <23> The end portions in the width direction of the stretchable sheet are blank portions that are not incorporated into the subsequent product. The method for manufacturing a stretchable composite sheet according to <22>.

[0060] <24> A method for manufacturing a sheet product using a stretchable composite sheet obtained by the method for manufacturing a stretchable composite sheet according to any one of <1> to <23>. <25> A method for manufacturing a mask having a step of cutting a stretchable composite sheet obtained by the method for manufacturing a stretchable composite sheet according to any one of <1> to <23> into a mask shape. <26> The method for manufacturing a sheet product according to <24> or <25>, wherein the stretchable composite sheet is the outermost layer of the sheet product or the mask.

Example

[0061] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not construed as being limited thereby.

[0062] (Example 1) The raw material sheet 1 has a length of 180 mm in the width direction X and a basis weight of 44 g / m 2 and is in the form of a long strip and prepared in the form of a raw material roll. The stretchable material of the raw material sheet 1 is a stretchable non-woven fabric. The layer structure of the raw material sheet 1 is a structure in which an elastomer is sandwiched between non-woven fabrics. The above-described [stretching step] was performed on the raw material sheet 11 under the conditions shown in Table 1 using the manufacturing apparatus of FIG. 1. Immediately after the [stretching step], a laminate of a fine fiber layer and a protective layer was laminated to form a stretchable sheet 12. The basis weight of the stretchable sheet 12 is 74.8 g / m2 was used. The fine fiber layer is a layer with an average fiber diameter of 0.55 μm and a basis weight of 4 g / m spun by the electrospinning method, and the protective layer is a spunbond nonwoven fabric with an average fiber diameter of 17.4 μm and a basis weight of 18 g / m 2 . 2 Another sheet 41 was made the same as the stretchable sheet 12 including the laminate of the above-mentioned fine fiber layer and protective layer. The above-mentioned stretchable sheet 12 and another sheet 41 were joined together, and the [Shrinking Process] and [Sealing Process] were performed to carry out the manufacturing method of the stretchable composite sheet of Example 1. In the [Stretching Process], a grooved roll was used. In the [Shrinking Process], when the elongation rate of the stretchable sheet 12 immediately after the [Stretching Process] was set to 1.00 times, the elongation rate of the stretchable sheet 12 immediately after the [Shrinking Process] was set to 0.59. In the [Sealing Process], ultrasonic welding was performed to form the seal portion 61 shown in Fig. 3. The formed seal portion 61 was a narrow strip having an extension length of 162 mm in an arc shape in the width direction and a seal width of 8 mm. The arc-shaped seal portion 61 arranged the joining portions of the sheets in a mesh shape within the above-mentioned seal width, and made the island-shaped portions between the mesh-shaped joining portions non-joining portions.

[0063] (Examples 2 to 4) In the [Shrinking Process], the manufacturing methods of the stretchable composite sheets of Examples 2 to 4 were carried out in the same manner as in Example 1 except that the elongation rate after shrinking was as shown in Table 1.

[0064] (Comparative Example) The manufacturing method of the stretchable composite sheet of Comparative Example 1 was carried out in the same manner as in Example 1 except that the [Shrinking Process] was not performed.

[0065] (Appearance Evaluation Method) Five judges proficient in sheet processing visually judged the sagging and wrinkles of the sheet, and a sensory evaluation was performed based on the average of the five judgments. Sample 1 was given 100 points and Sample 2 was given 0 points, and the scores of each example and comparative example were assigned.

[0066]

Table 1

[0067] As shown in Fig. 8, in the production methods of Examples 1 to 3, since the [shrinking step] in which the elongation rate after shrinking is set to 0.84 times or less was included, a stretchable composite sheet with a better appearance of the seal portion could be produced as compared with the production method of the comparative example that does not include the [shrinking step]. That is, according to the production method of the stretchable composite sheet of the present invention, it was found that a stretchable composite sheet with good appearance can be suitably produced while imparting high stretchability and reducing seal sagging and the like.

Explanation of Signs

[0068] 1 Master roll 11 Raw material sheet 12 Stretchable sheet 2 Stretching mechanism 21 First roll device 23 Second roll device 3 Shrinking mechanism 4 Master roll 41 Another sheet 5 Sealing mechanism 6 Stretchable composite sheet

Claims

1. having a stretching process, the stretching process comprising: feeding a raw material sheet containing an elastic material between a pair of meshing serrated rolls and subjecting the raw material sheet to stretching to form an elastic sheet; after the stretching process, a shrinking process of shrinking the drawn elastic sheet to a weakened stretched state that is weaker than the stretched state immediately after being drawn and that is stretched more than the natural state in which the stretching force is released; a sealing process of joining the elastic sheet to another sheet in the weakened stretched state to form seal portions arranged at intervals in the conveying direction; A method for manufacturing a stretchable composite sheet having the above.

2. The shrinking process shrinks the elastic sheet immediately after the shrinking process to a stretch ratio of 0.84 times or less when the stretch ratio of the elastic sheet immediately after the stretching process is set to 1.00 times. The method for manufacturing a stretchable composite sheet according to Claim 1.

3. The sealing process performs welding by ultrasonic waves. The method for manufacturing a stretchable composite sheet according to Claim 1 or 2.

4. Each seal portion formed in the sealing process has a continuous inclined portion of 1 mm or more in a direction intersecting the stretching direction of the elastic sheet in a plan view of the elastic sheet. The method for manufacturing a stretchable composite sheet according to any one of Claims 1 to 3.

5. A method for manufacturing a stretchable composite sheet according to any one of Claims 1 to 4, having a process of subjecting the elastic sheet to a process for suppressing stretching behavior between the shrinking process and the sealing process.

6. The stretching process is as follows: Controlling the conveyance speed and / or tension of the raw material sheet by a first roll device on the upstream side and a second roll device on the downstream side to apply a stretching force in the conveyance direction to the raw material sheet; Supplying the raw material sheet between a pair of meshing serrated rolls arranged between the first roll device and the second roll device by the first roll device and subjecting the raw material sheet to stretching to form an elastic sheet; A process of pulling out the elastic sheet downstream in a state of being stretched in the conveyance direction by the stretching force by the second roll device. The method for manufacturing a stretchable composite sheet according to any one of Claims 1 to 5.

7. A method for manufacturing a mask having a process of cutting a stretchable composite sheet obtained by the method for manufacturing a stretchable composite sheet according to any one of Claims 1 to 6 into a mask shape. ​

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