Method for producing fiber laminate sheet

Abstract

To provide a method for producing a fiber laminate sheet excellent in scratch resistance while containing ultrafine fibers.SOLUTION: A spinning step of spinning fibers having a fiber diameter of 0.3 μm or more and 5 μm or less on a support sheet and laminating the fibers, the spinning step including discharging a molten resin from a nozzle and drawing and fiberizing the molten resin by a gas flow jetted along a discharge direction at a side of the nozzle, wherein in the spinning step, (1) a space temperature T1 at a position of 50 mm from a tip of the nozzle is set to 80 °C or higher and 180 °C or lower, and a space temperature T2 at a position of 100 mm from the tip of the nozzle is set to 40 °C or higher and 120 °C or lower, (2) The method for producing a fiber laminate sheet according to (1), wherein a temperature Tc at which a storage stiffness modulus (G ') and a loss stiffness modulus (G ") cross each other is 30 °C. or higher and 80 °C. or lower in a dynamic viscoelasticity curve obtained at a temperature lowering rate of 4 °C. / min from a molten state at 200 °C., and a space temperature 25mm at a position before the T3 is higher than the temperature Tc.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fiber laminated sheet. [Background technology]

[0002] In the field of melt spinning techniques for fiber sheets, such as melt electrospinning and meltblowing, techniques are known in which the physical properties of the resulting fibers are characterized by introducing air near the tip of the spinning nozzle. For example, Patent Document 1 describes a technology related to a process for forming meltblown fibers using a meltblowing die. In this process, a controlled air-heat treatment is performed at a temperature lower than the melting temperature of a portion of the meltblown fibers in order to suppress fiber shrinkage due to heating and obtain dimensional stability. The air-heat treatment is performed on the meltblown fiber stream immediately after it emerges from the orifice of the meltblowing die. During or after the air-heat treatment, the fine fibers begin to solidify, forming a cohesive web when they reach a collector. Patent Document 2 describes a technology related to a method for producing a nanofiber aggregate. In this production method, high-temperature, high-pressure gas and a lower-temperature, high-pressure gas close to room temperature are both ejected near a solution ejection port for ejecting a raw material solution. The former ejection is a process for generating and stretching the ejected raw material solution as a nanofiber flow, while the latter ejection is a process for suppressing the stretching action by using the low temperature and disturbing the nanofiber flow to three-dimensionally agitate the nanofiber fibers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2016-538439 [Patent Document 2] Japanese Patent Publication No. 2020-153027 Summary of the Invention [Problem to be solved by the invention]

[0004] By reducing the diameter of the fibers in the melt spinning process, the flexibility of the fiber sheet made using these fibers increases. However, fiber sheets with reduced diameters, especially those made by depositing ultrafine fibers (e.g., fiber diameters of 5 μm or less), have weak fiber strength and are prone to tearing when handled (e.g., pulled) alone. Therefore, it is desirable to integrate a fiber sheet made using thinned fibers with a sheet (hereinafter referred to as a support sheet) that ensures strength to improve its handleability. However, simply depositing thinned fibers obtained by melt spinning on a support sheet using conventional spinning technology to form a fiber laminate sheet does not provide sufficient strength for integration with the fibers of the support sheet due to the thinness of the spun fibers, and there is room for improvement. In particular, there is room for improvement in the strength of the fiber laminate sheet to withstand abrasion such as friction when applied to the skin, etc. In this regard, Patent Documents 1 and 2 do not disclose any description of the above problems or means for solving them.

[0005] In view of the above, the present invention relates to a method for producing a fiber laminated sheet that contains ultrafine fibers and has excellent abrasion resistance. [Means for solving the problem]

[0006] The present invention has a spinning process in which fibers having a fiber diameter of 0.3 μm or more and 5 μm or less are spun and laminated on a support sheet, and the spinning process is performed by discharging a molten resin from a nozzle and fiberizing it by a gas flow that is ejected at the side of the nozzle along the direction of the discharge, and in the spinning process, in a space from the tip of the nozzle to the support sheet, (1) a space temperature T1 at a position 50 mm from the tip of the nozzle is set to 80° C. or more and 180° C. or less, and a space temperature T2 at a position 100 mm from the tip of the nozzle is set to 80° C. or more and 180° C. or less. (1) a temperature T2 of 40°C or higher and 120°C or lower is set; and (2) the space is heat-treated so that the space temperature T3 at a position 25 mm in front of the surface of the support sheet is higher than the following temperature Tc by (Tc-10°C), and the molten resin has a dynamic viscoelasticity curve obtained by cooling from a molten state at 200°C at a rate of 4°C / min, where the temperature Tc at which the storage modulus (G') and loss modulus (G'') intersect is 30°C or higher and 80°C or lower.

[0007] The present invention also provides a fiber laminated sheet having a first fiber layer having a median fiber diameter of 0.3 μm or more and 5 μm or less and a second fiber layer adjacent thereto having a median fiber diameter of 5 μm or more and 50 μm or less, wherein the first fiber layer and the second fiber layer contain the same material, and the same material is selected from an olefin resin, a diene resin, a urethane resin, and copolymers thereof; The first fiber layer and the second fiber layer are integrated by the fusion-bonded intersections of the fibers of each other, and the T-peel strength of the laminated sheet is 0.5 N / 50 mm or more. [Effects of the Invention]

[0008] According to the method for producing a fiber laminated sheet of the present invention, a fiber laminated sheet that contains ultrafine fibers and yet has excellent abrasion resistance can be suitably produced. The fiber laminated sheet of the present invention has excellent abrasion resistance. [Brief explanation of the drawings]

[0009] [Figure 1]1 is an explanatory diagram schematically illustrating one embodiment of a spinning device used in a method for producing a fiber laminated sheet of the present invention. [Figure 2] FIG. 2 is an explanatory diagram schematically illustrating another embodiment of a spinning device used in the method for producing a fiber laminated sheet of the present invention. [Figure 3] 1 is a graph showing a dynamic viscoelasticity curve of an example of a molten resin used in the method for producing a fiber laminated sheet of the present invention. [Figure 4] 1 is a graph showing a dynamic viscoelasticity curve of another example of a molten resin used in the method for producing a fiber laminated sheet of the present invention. [Figure 5] This is a photograph in place of a drawing showing an example of holes that occur in a fiber laminated sheet when the space temperature between the tip of the nozzle and the surface of the support sheet in the fiber laminated sheet manufacturing method of the present invention exceeds the specified space temperatures T1 and T2. [Figure 6] 1A and 1B are photographs in lieu of drawings showing examples of the fiber structure of a fiber laminated sheet obtained when the manufacturing method of the fiber laminated sheet of the present invention is carried out under specified temperature control, where (A) shows an example of the fiber structure at one end of the manufacturing line, (B) shows the central side, and (C) shows the other end side. [Figure 7] 1 is a graph showing an example of the relationship between the distance between the tip of the nozzle and the surface of the support sheet and the space temperature in the method for producing a fiber laminated sheet of the present invention. [Figure 8] FIG. 2 is an enlarged perspective view schematically illustrating an example of fusion-bonded intersections between the fibers of the ultrafine fiber layer and the fibers of the support sheet, which are formed by the method for producing a fiber laminated sheet of the present invention. [Figure 9] 1 is a cross-sectional view schematically showing one embodiment of a fiber laminated sheet according to the present invention. [Figure 10] 1 is a graph showing the relationship between the sheet width and the T-peel strength of fiber laminated sheet samples produced in Example 1 and Comparative Example 1. [Figure 11] 1 is a photograph showing holes formed as a result of a T-peel strength test on the fiber laminated sheet of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] The method for producing a fiber laminated sheet of the present invention will be described below with reference to the drawings. The method for producing a fiber laminated sheet of the present invention includes a spinning step of spinning and laminating fibers onto a support sheet. The support sheet is composed of fibers, and various sheets can be used that provide strength sufficient to improve handleability while maintaining the flexibility of the fiber laminated sheet of the present invention. Examples include spunbond nonwoven fabrics, air-through nonwoven fabrics, air-laid nonwoven fabrics, and spunlace nonwoven fabrics.

[0011] The spinning process involves discharging a molten resin from a nozzle and forming it into fibers by a gas flow that is ejected from the side of the nozzle in the direction of the discharge. This is done using a spinning method known as direct spinning, such as melt-blowing or melt electrospinning (also known as melt electrospinning).

[0012] Such a spinning process can be carried out using various devices that can discharge molten resin using a nozzle and can suitably reduce the diameter. For example, the device shown in Fig. 1 and Fig. 2 can be used. The spinning device 10 of Fig. 1 can be used to carry out a spinning process, for example, by a melt-blowing method. The spinning device 10A of Fig. 2 differs from the spinning device 10 of Fig. 1 in that it has an electrode 32 arranged around the nozzle 31. The spinning device 10A of Fig. 2 can be used to carry out a spinning process, for example, by a melt electrospinning method. The direction in which the molten resin is discharged from the nozzle can be set in various ways depending on the arrangement of the support sheet, and may be, for example, horizontal or vertical as shown in Figures 1 and 2. When the discharge direction is vertical, the tip of the nozzle is directed downward, and the support sheet is placed below it. However, considering the tendency for heat to escape upward, it is preferable to set the discharge direction horizontal as shown in Figures 1 and 2, as this makes it easier to control the space temperature T3 on the support sheet side described above in the present invention to a high temperature.

[0013] The spinning apparatus 10 shown in FIG. 1 includes a kneading device 20 and a spinning unit 30. The kneading device 20 melts the resin that is the raw material for the fibers and extrudes it into the spinning unit 30, which will be described later. The kneading device 20 has a cylinder and a screw equipped with a heater inside, and is configured to melt and knead the raw material resin supplied into the kneading device 20 and extrude it into the spinning unit 30. The spinning unit 30 discharges the molten resin supplied from the kneading device 20 to the outside and spins it. The spinning unit 30 is equipped with a hollow nozzle 31 that is in communication with the kneading device 20. The nozzle 31 is configured so that the molten resin supplied from the kneading device 20 can be discharged from a nozzle tip 31a of the nozzle 31 via a resin supply path 31b, which will be described later. In the following description, unless otherwise specified, the direction toward the kneading device 20 as viewed from the nozzle 31 is also referred to as the "rear" or "rear end direction," and the direction opposite to this direction is also referred to as the "front" or "front end direction."

[0014] Between the kneading device 20 and the nozzle 31, a structure formed by a cylindrical resin supply path 31b and a tube 36 arranged to surround the resin supply path 31b is arranged. The resin supply path 31b is connected to the kneading device 20, allowing molten resin supplied from the kneading device 20 to flow toward the nozzle 31. The space formed between the resin supply path 31b and the tube 36 serves as a gas injection section 40 through which a gas flow A can flow. In other words, the gas injection section 40 is arranged to surround the nozzle 31. A gas flow A from a gas supply source can be supplied to each gas injection section 40, 40 via a gas inlet 40a, and the gas flow A is injected from a gas injection port 40p. As shown in FIG. 1, the gas injection section 40 is configured to inject the gas flow A from the rear end of the nozzle 31 (i.e., the kneading device 20 side) toward the nozzle tip 31a and along the extension direction of the nozzle 31. As a result, as described above, the gas flow A is ejected from the side of the nozzle 31 in the direction in which the molten resin is ejected from the nozzle 31. The ejected molten resin is stretched and reduced in diameter by this gas flow A. From the viewpoint of convenience, an air flow, for example, can be used as the gas flow A.

[0015] From the viewpoint of stretching the extruded molten resin with the gas flow A and facilitating the formation of ultra-thin fibers, it is preferable that the gas injection section 40 is formed in a ring shape so as to surround the outer periphery of the resin supply path 31b and the nozzle 31, or that multiple gas injection sections 40 are arranged along the extension direction of the nozzle 31 and so as to surround the nozzle 31.

[0016] It is preferable that the gas flow A is heated from the viewpoint of stretching the discharged molten resin and thereby reducing the diameter thereof. "Heated" means that the temperature is higher than the standard temperature (20°C).

[0017] In the spinning device 10, the nozzle 31 ejects molten resin toward the support sheet 1 that is placed at a position spaced a certain distance from the tip 31a of the nozzle 31. In Fig. 1, support sheet 1 is a long continuous sheet unwound from support sheet roll 1R and continuously transported by belt conveyor 60. As a result of this transport, support sheet 1 receives, in the sheet flow direction, the molten resin that is discharged from nozzle 31 and reduced in diameter at a position opposite tip 31a of nozzle 31. As a result, an ultrafine fiber layer 2 is formed on the surface of support sheet 1, and a fiber laminated sheet 3 consisting of support sheet 1 and ultrafine fiber layer 2 is continuously formed (note that in the description of the fiber laminated sheet described below, ultrafine fiber layer 2 will be described as the first fiber layer and support sheet 1 will be described as the second fiber layer).

[0018] As described above, the spinning apparatus 10A shown in FIG. 2 differs from the spinning apparatus 10 in FIG. 1 in that it has an electrode 32 arranged around the nozzle 31. The electrode 32 is made of a conductive material, charges the nozzle 31, and generates an electric field between the nozzle 31 and the support sheet 1. From the viewpoint of improving the charging properties of the nozzle 31, it is preferable that the nozzle 31 be made of a conductor such as a metal. The electrode 32 in the figure has a roughly bowl shape and is disposed so as to surround the nozzle 31. The surface of the electrode 32 facing the nozzle 31 is formed into a concave curved shape. For ease of explanation, in the following explanation, the surface of the electrode 32 facing the nozzle 31 will also be referred to as the "concave curved surface 32a." The electrode 32 has an open end 32c on the tip side of the nozzle 31, and the planar shape of the open end 32c is a circular shape such as a perfect circle or an ellipse. The electrode 32 is connected to a high-voltage generator, and a positive or negative voltage is applied to it by the generator.

[0019] It is preferable that the concave curved surface 32a is a curved surface at all positions. The curved surface referred to here means either (a) a curved surface that has no flat portions at all, (b) a shape that can be regarded as a concave curved surface as a whole by connecting a plurality of segments that have flat portions, or (c) a shape that can be regarded as a concave curved surface as a whole by connecting a plurality of annular segments that have a band-shaped portion with no curvature on one of three mutually perpendicular axes.

[0020] From the viewpoint of facilitating the concentration of electric charge on the nozzle 31 and increasing the amount of charge on the discharged molten resin, the concave curved surface 32a is preferably formed so that a normal line at any position on the concave curved surface 32a passes through the nozzle tip 31a or its vicinity, and it is more preferable that the concave curved surface 32a has the same shape as the inner surface of a spherical shell. Similarly, it is also preferable that the opening end 32c is a perfect circle.

[0021] A collecting electrode made of a conductive material such as metal is disposed on the belt conveyor 60, which is a conveying device for the support sheet 1 and faces the spinning apparatus 10A. The spun fibers can be collected on the base sheet 1 due to the potential difference between the nozzle 31 and the collecting electrode. The collecting electrode is preferably flat, and it is also preferable that the plate surface of the collecting electrode is approximately perpendicular to the direction in which the nozzle 31 extends. The collecting electrode is preferably grounded or has a voltage applied thereto by a high-voltage power supply. In the latter case, it is also preferable that a voltage different from the voltage applied to the nozzle 31 is applied to the belt conveyor 60. In the spinning apparatus 10A, in addition to the gas flow A, the Coulomb force caused by the generated electrolysis can make it possible to draw the molten resin more effectively.

[0022] In the method for producing a fiber laminated sheet of the present invention, the molten resin used has the property that, in a dynamic viscoelasticity curve obtained by cooling from a molten state at 200°C at a rate of 4°C / min, the temperature Tc at which the storage modulus (G') and loss modulus (G'') intersect is 30°C or higher and 80°C or lower.

[0023] The molten resin may include various types of resins having a temperature Tc of 30° C. or higher and 80° C. or lower. Specific examples thereof include molten resins that exhibit dynamic viscoelasticity curves shown in FIGS. The molten resin for which the dynamic viscoelasticity curve in FIG. 3 is shown has a temperature Tc of around 39°C. The molten resin for which the dynamic viscoelasticity curve in FIG. 4 is shown has a temperature Tc of around 72°C.

[0024] The above temperature requirement means that the temperature Tc of the molten resin is lower than that of resins generally used in conventional fiber sheets, i.e., the above temperature requirement means that the molten resin exhibiting the dynamic viscoelasticity curve has lower crystallinity than that of resins generally used in conventional fiber sheets. As a result, the temperature range in which the molten resin is in a flowable state before it becomes rubbery is wider than before, and the molten resin is likely to maintain a low-viscosity flowable state even when the temperature is lowered from 200°C to a temperature Tc that is relatively close to room temperature. Furthermore, the molten resin having the above temperature characteristics is easy to thin in diameter in the spinning process, and has the advantage of increasing the flexibility of the fiber laminated sheet made using this.

[0025] In the method for producing a fiber laminated sheet of the present invention, a heat treatment is carried out using a molten resin that exhibits the above-mentioned dynamic viscoelasticity curve, to suitably control the spatial temperature in the spinning process (the spatial temperature along the nozzle axis from the tip of the nozzle to the surface of the support sheet). That is, in the spinning process, the space from the tip of the nozzle to the support sheet is heat-treated so that (1) the space temperature T1 at a position 50 mm from the tip of the nozzle is 80°C or higher and 180°C or lower, and the space temperature T2 at a position 100 mm from the tip of the nozzle is 40°C or higher and 120°C or lower, and (2) the space temperature T3 at a position 25 mm in front of the surface of the support sheet is higher than the temperature Tc by (Tc-10°C).

[0026] In this way, the temperature of the entire space from the tip of the nozzle to a position 25 mm in front of the surface of the support sheet is set to a temperature higher than the aforementioned temperature (Tc-10°C). That is, the molten resin discharged from the tip of the nozzle is maintained in a fluid state by taking advantage of the characteristics of the dynamic viscoelastic curve described above until it reaches the surface of the support sheet, and is successfully stretched and thinned. Furthermore, the thinned molten resin is easily fused to the fibers of the support sheet in a fluid state. In addition, by setting the space temperatures T1 and T2 as described above, the space temperature T2 in particular is controlled so as not to become too high. This prevents the molten resin, which exhibits the dynamic viscoelastic curve described above, from becoming excessively fluid, thereby preventing the molten resin from breaking in a viscous fluid state and the resulting granulation and thickening of the fibers. As a result, the thinned fiber shape is maintained until it reaches the support sheet, and fusion intersections (bonding points) with the fibers of the support sheet are formed satisfactorily. This results in a stronger integration between the softened ultrafine fiber layer and the support sheet. As a result, the manufactured fiber laminated sheet has improved abrasion resistance due to the integration of the ultrafine fiber layer and the support sheet. Furthermore, by preventing the molten resin from breaking into granules or increasing in diameter, the granules or larger diameter portions of the molten resin do not penetrate the support sheet, thereby preventing the formation of holes (see, for example, Figure 5). By preventing penetration into the support sheet, adhesion to the belt conveyor, which is the transport means, is also reduced, preventing tearing when the fiber laminated sheet is peeled off from the belt conveyor. As a result, the fiber laminated sheet produced has a good appearance, and the ultrafine fiber layer 2 has good softness and adheres well to the skin. For example, as shown in Figures 6(A) to 6(C), there are no holes like those shown in Figure 5 at one end, center, or other end of the fiber laminated sheet in the width direction, resulting in a good, integrated fiber laminate state.

[0027] Such temperature control is, for example, as shown in Figure 7. Figure 7 shows a graph of the relationship between the linear distance from the tip of the nozzle to the surface of the support sheet, with the horizontal axis representing the nozzle tip at 0 mm, and the vertical axis representing the spatial temperature. As shown in Figure 7, first, the space temperature T1 at position S1, 50 mm from the tip of the nozzle, is set to between 80°C and 180°C. Position S1 refers to the space where the molten resin has just been extruded from the tip of the nozzle. By setting the space temperature T1 within the above temperature range, the fluidity of the resin immediately after extrusion from the nozzle is increased, making it easier to draw and thin the resin, while also preventing the resin from breaking due to overheating. Next, in the space from position S1 (50 mm) to position S2 (100 mm), the space temperature is reduced from the temperature range of T1 to the temperature range of T2. During this reduction in the space temperature from position S1 to position S2, the molten resin in a fluid state is stretched and thinned by the aforementioned gas flow. The molten resin does not become excessively fluid, and simultaneously with the thinning of the diameter, it gradually hardens as the space temperature is reduced. However, because the space temperature at position S2 is also set to a moderately high temperature as described above, the fluid state of the thinned molten resin is maintained at a moderate level. In this way, by appropriately controlling the fluid state of the molten resin from position S2, an early stage after discharge, to prevent it from becoming excessively fluid (to prevent it from becoming too viscous), even when the stretching action of the gas flow is applied, the molten resin is less likely to break and become granular or thickened. In other words, the thinned fiber shape of the molten resin is easily maintained. The space temperature T3 at position S3, from the remaining 100 mm to 25 mm before the surface of the support sheet, is maintained at a temperature higher than Tc-10°C. This space temperature T3 is kept low enough to prevent the molten resin from becoming excessively fluid. At position S3, the molten resin reaches the surface of the support sheet in a moderately fluid state while the aforementioned diameter reduction and hardening continue. As a result, as shown in Figure 8, for example, the diameter-reduced fibers 21 maintain their fiber shape and successfully form fusion intersections (bonding points) K with the fibers 11 of the support sheet. The manufactured fiber laminate sheet has improved abrasion resistance due to the integration of the ultrafine fiber layer 2 and the support sheet 1. Furthermore, hole formation is suppressed. The space temperature T3 is preferably 30° C. or higher from the viewpoint of successful integration with the support sheet. The space temperature T3 is preferably 100° C. or less from the viewpoint of stabilizing the thinning of the fibers and hardening.

[0028] From the viewpoint of reducing the diameter, the space temperature T1 is preferably 100° C. or higher, and more preferably 120° C. or higher. The space temperature T1 is preferably 170° C. or less, more preferably 160° C. or less, from the viewpoint of ensuring the quality of the resin. The space temperature T2 is preferably 50° C. or higher, more preferably 60° C. or higher, from the viewpoint of successful integration with the support sheet. The space temperature T2 is preferably 110° C. or less, more preferably 100° C. or less, from the viewpoint of stabilizing the thinning of the fibers and hardening.

[0029] The heating treatment may be performed by ejecting the gas flow, or may not be performed by using a gas flow. In either case, it is preferable that the heating treatment includes ejecting hot air into the space. This ejection of hot air can be performed, for example, by a hot air ejection unit 50 shown in Figures 1 and 2. The hot air ejection unit 50 is disposed on the support sheet 1 side, away from the tip 31a of the nozzle 31, and ejects hot air B from a hot air ejection port 50p onto the extruded molten resin.

[0030] At this time, the reduction in the space temperature in the space from the 50 mm position S1 to the 100 mm position S2 (reducing the space temperature from T1 to T2) is preferably controlled by the gas flow. Maintaining the temperature in the space from the 100 mm position S2 to the surface of the support sheet at or above (TC-10°C) is preferably controlled by the gas flow and / or the hot air. The space temperature T1 at the position S1 can be controlled by the gas flow and the temperature of the molten resin itself (the melt heating temperature in the kneading device 20).

[0031] (Method for measuring temperatures at positions S1, S2 and S3, including space temperatures T1, T2 and T3) The space temperature at positions S1, S2, and S3 is measured using a K-type thermocouple. The measurement interval is one second, and the average value for one minute is taken as the space temperature at the positions.

[0032] The hot air preferably merges with the gas flow closer to the support sheet than the intermediate position in the linear distance from the nozzle tip to the surface of the support sheet. This allows the space temperature T1 to be controlled so as not to decrease too much at the merging point, making it possible to maintain a space temperature T3 higher than the aforementioned temperature (Tc - 10°C). From this perspective, the intermediate position is preferably the aforementioned 100 mm position S2.

[0033] The reduction of the space temperature from T1 to T2 in the space from position S1 to position S2, and the maintenance of the space temperature from position S2 onwards, can be suitably controlled by appropriately combining the temperature, flow velocity and flow rate of the gas flow, the temperature, flow velocity and flow rate of the hot air, and further the distance from the tip of the nozzle to the surface of the support sheet. For example, the temperature of the gas flow is preferably 200°C or higher and 350°C or lower in order to maintain the molten state of the resin immediately after it is discharged from the nozzle. From the viewpoint of successful drawing, the flow rate of the gas flow is preferably 50 m / s or more, more preferably 100 m / s or more. From the viewpoint of fiber collection efficiency, the distance between the tip of the nozzle and the support sheet is set to preferably 50 mm or more, more preferably 100 mm or more, and preferably 2000 mm or less, more preferably 1500 mm or less.

[0034] In the method for producing a fiber laminated sheet of the present invention, it is preferable that the nozzle ejects hot air from outside the gas flow. For example, when the nozzles are arranged in multiple rows in the width direction of the support sheet, the heat emitted from the nozzles tends to escape more easily from the nozzles in the width direction (one end side, the other end side) than from the nozzles in the center. By injecting the hot air, this problem can be solved, and the method for producing a fiber laminated sheet of the present invention can be performed more effectively. Specifically, the hot air is preferably injected so as to merge with the gas flow, i.e., the injector is preferably installed at an angle to the axis extending from the nozzle, preferably at an angle of 10° to 80°, more preferably at an angle of 30° to 60°, relative to the axis extending from the nozzle. To prevent the resin discharged from the nozzle from adhering to the sprayer, the sprayer is preferably installed at a distance of 50 mm or more from the axis of the nozzle. In order to improve the stretching behavior, the flow velocity of the hot air is preferably lower than that of the gas flow, specifically, preferably 15 m / s or less, more preferably 10 m / s or less. From the viewpoint of achieving good integration with the support sheet, the hot air temperature at the outlet of the spray device is preferably 100°C or higher. On the other hand, in order to keep the temperature after position S2 within an appropriate range, the hot air temperature is preferably 350°C or lower.

[0035] According to the method for producing a fiber laminated sheet of the present invention, a fiber laminated sheet having the following configuration can be produced. That is, the fiber laminated sheet of the present invention has a first fiber layer having a median fiber diameter of 0.3 μm to 5 μm and an adjacent second fiber layer having a median fiber diameter of 5 μm to 50 μm. As described above, the first fiber layer and the second fiber layer are the ultrafine fiber layer and the support sheet, respectively, shown in the manufacturing method of the fiber laminated sheet of the present invention. As described above, the first fiber layer and the second fiber layer are integrated by the fusion intersections of the fibers.

[0036] For example, the fiber laminated sheet 100 shown in FIG. 9 has a first fiber layer M and an adjacent second fiber layer N. The first fiber layer M is disposed on one side F of the front and back surfaces of the fiber laminated sheet 100, and the second fiber layer N is disposed on the other side B opposite to the one side F. The fiber laminated sheet of the present invention is not limited to this configuration and may further include another fiber layer in addition to the first fiber layer M and the second fiber layer N. In this case, the other fiber layer is preferably disposed on the other side B of the second fiber layer N from the viewpoint of effectively utilizing the properties of the first fiber layer M described below and not impairing the strong integration between the first fiber layer M and the second fiber layer N. In other words, the first fiber layer M is preferably disposed as the outermost layer of the fiber laminated sheet 100.

[0037] The first fiber layer contains ultrafine fibers with a median fiber diameter (P1) of 0.3 μm or more and 5 μm or less. Because of the fineness of the fibers, such a first fiber layer has less unevenness per fiber than conventional fiber layers such as nonwoven fabrics, increasing the contact area with the target (e.g., the skin surface) and enhancing adhesion to the target. For this reason, it is preferable that the first fiber layer side of the fiber laminated sheet of the present invention be the surface facing the target.

[0038] The median fiber diameter (P1) of the first fiber layer is preferably 5 μm or less, more preferably 3 μm or less, even more preferably 2 μm or less, and most preferably 1 μm or less, from the viewpoint of further improving adhesion to an object such as the skin surface. The median fiber diameter (P1) of the first fiber layer is preferably 0.3 μm or more, more preferably 0.4 μm or more, and even more preferably 0.5 μm or more, from the viewpoint of improving abrasion resistance and imparting durability to withstand the stretching action described below.

[0039] The second fiber layer contains fibers with a median fiber diameter (P2) of 5 μm or more and 50 μm or less. By having this median fiber diameter, the second fiber layer imparts strength and rigidity to the entire fiber laminated sheet of the present invention, including the first fiber layer, and improves resistance to tearing and abrasion, without impairing the aforementioned adhesive properties of the first fiber layer. This second fiber layer can be obtained by appropriately setting the median fiber diameter using a method commonly used for this type of article. For example, a spunbond nonwoven fabric can be mentioned.

[0040] The median fiber diameter (P2) of the second fiber layer is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 25 μm or less, from the viewpoint of thinning the entire fiber laminated sheet of the present invention and improving adhesion to an object. The median fiber diameter (P2) of the second fiber layer is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 15 μm or more, from the viewpoint of improving resistance to tearing and abrasion.

[0041] The ratio (P2 / P1) of the median fiber diameter (P2) of the second fiber diameter to the median fiber diameter (P1) of the first fiber diameter is preferably 1.5 or more, more preferably 10 or more, and even more preferably 20 or more, from the viewpoint of increasing the strength of the entire fiber laminated sheet of the present invention while maintaining the adhesive properties of the first fiber layer to the skin surface. Furthermore, the ratio (P2 / P1) is preferably 170 or less, more preferably 150 or less, and even more preferably 100 or less, from the viewpoint of reducing the overall thickness of the fiber laminated sheet of the present invention to enhance the adhesion, and from the viewpoint of enhancing the elasticity described below.

[0042] (Method for measuring median fiber diameter) From two-dimensional images obtained by scanning electron microscopy, 200 fibers were randomly selected, excluding defects such as fiber clumps, intersections of constituent fibers, and polymer droplets, and the width perpendicular to the longitudinal direction (fiber length direction) of each fiber (the length of a line drawn through the center of the fiber in a cross section perpendicular to the longitudinal direction of the constituent fibers) was measured. If the cross section perpendicular to the longitudinal direction of the fiber is not circular, the average fiber diameter was converted to a circular equivalent diameter. From the measured fiber diameters of the 200 fibers, the number average diameter, the diameter of several tens of percent (from the thinnest diameter side), the diameter of several 50% (median diameter), and the diameter of several 90% were tallied. Of these, the median diameter was used as the representative value of the fiber diameter.

[0043] In the fiber laminated sheet of the present invention, the first fiber layer and the second fiber layer contain the same material, which means a material in which the repeating unit (monomer structure) has the same polymer structure. Since the first and second fiber layers contain the same material, the molecular structures of the resin components are similar and the fibers are highly compatible with each other, which facilitates strong fusion bonding between the first and second fiber layers (strengthening the aforementioned fusion intersections (bonding points)), thereby enhancing the integrity of the fiber laminated sheet of the present invention. The homogeneous material is selected from olefin resins, diene resins, urethane resins, and copolymers thereof.

[0044] (Method for measuring whether the first and second fiber layers contain the same material) To determine whether the first and second fiber layers contain the same material, the fiber layers are peeled apart and the resin composition contained in each fiber layer is measured. The resin composition is subjected to various analyses, such as nuclear magnetic resonance (NMR) analysis and infrared spectroscopy (IR) analysis, and the molecular skeleton structure and the functional group structure at the terminals of the molecular structure are identified based on the positions of each signal and spectrum obtained by these analyses. This identifies and specifies the type of resin contained in each fiber layer. The resin compositions identified for each fiber layer are compared to determine whether they contain the same material.

[0045] The fiber laminated sheet of the present invention has high integrity between the adjacent first and second fiber layers. This integrity makes it difficult for peeling to occur at the interface between the first and second fiber layers when the fiber laminated sheet of the present invention is stretched or contracted. Suppressing peeling imparts strength or rigidity to the entire fiber laminated sheet of the present invention, resulting in overall stiffness. This gives the fiber laminated sheet of the present invention excellent abrasion resistance.

[0046] The fiber laminated sheet of the present invention has the above-mentioned abrasion resistance, and has a T-peel strength (N / 50 mm) of 0.5 N / 50 mm or more. The T-peel strength being equal to or greater than a predetermined lower limit means that the fiber laminated sheet of the present invention is strong enough to withstand the abrasion force when it is brought into contact with the skin or the like. In particular, when it is used as a glove and worn on the hand, the frictional force is relatively large, and this strength means that the fiber laminated sheet can withstand that friction. In this regard, fiber laminated sheets formed by conventional direct spinning techniques using molten resin have a T-peel strength of, for example, about 0.1 N / 50 mm to 0.2 N / 50 mm. In contrast, the T-peel strength of the fiber laminated sheet of the present invention is as described above, and is significantly higher despite including a first fiber layer of ultrafine fibers. From the above viewpoints, the T-peel strength of the fiber laminated sheet of the present invention is more preferably 1 N / 50 mm or more, and even more preferably 1.5 N / 50 mm or more. The higher the T-peel strength, the better.

[0047] (Method for measuring T-peel strength) An adhesive tape is applied to the surface of the first fiber layer of the fiber laminated sheet, and the tape is peeled off in a T-shape using a tensile tester. This measures the strength of the fusion between the fibers of the first fiber layer and the second fiber layer at the interface between them. Specifically, the measurement is performed using the following procedure. An adhesive tape (width: 50 mm, adhesive strength: 3.9 N / 10 mm) is applied to the surface side of the first fiber layer of the fiber laminate sheet, and a test piece 50 mm wide and 150 mm long is then prepared. The overlap length between the first fiber layer and the tape in the longitudinal direction is 100 mm or more. The end of the tape (one end in the longitudinal direction) and the fiber laminate sheet (the same end in the longitudinal direction as the end of the tape) are pulled with a gripping distance of 50 mm and a pulling speed of 100 mm / min, and the test force at which the tape peels from the fiber laminate sheet is measured. The average of the test forces obtained when the gripper travels a distance of 30 mm or more and 130 mm or less from the initial position is taken as the T-peel strength of the fiber laminate sheet.

[0048] The fiber laminated sheet of the present invention has improved handleability due to its unity. Specifically, it has more stiffness than a fiber sheet consisting solely of a first fiber layer made of ultrafine fibers, making it easier to handle. For example, when removing one fiber laminated sheet of the present invention from a stack of multiple sheets or from a storage bag or container to use (e.g., apply to the skin), stiffness significantly affects the ease of removal. Furthermore, when removed, the fiber laminated sheet of the present invention is less likely to curl than a fiber sheet consisting solely of the first fiber layer, improving handleability. This allows it to be applied neatly to an object such as the skin without wrinkles.

[0049] Additionally, the fiber laminated sheet of the present invention contains the aforementioned elastomer resin component, and the peeling is highly suppressed, which makes it easier for the first fiber layer to stretch together with the second fiber layer. As a result, the fiber laminated sheet of the present invention as a whole has durability that can withstand repeated stretching and contraction. That is, the first fiber layer and the second fiber layer have high integrity, allowing the sheet to stretch while maintaining high overall sheet strength and rigidity. Therefore, during the stretching behavior of the fiber laminated sheet of the present invention, the first fiber layer is less likely to twist or be worn. Furthermore, shedding of the first fiber layer is also suppressed. Thus, the fiber laminated sheet of the present invention has improved overall stretchability and sheet strength, and even when stretchability is achieved, it has increased resistance to tearing and abrasion. Furthermore, the stretchability of the entire sheet allows the first fiber layer to conform to the shape and various changes (movements) of an object such as the skin surface, and the aforementioned adhesive properties can be fully exhibited even under such changes.

[0050] The above-mentioned homogeneous material is preferably an olefin-based resin from the viewpoint of enhancing the integrity of the first and second fiber layers and enhancing the stretchability of the fiber laminated sheet of the present invention including these layers. By using an olefin-based resin, the first fiber layer and the second fiber layer are less likely to peel off when the fiber laminated sheet of the present invention is stretched. From the same viewpoint, the first fiber layer preferably contains a low-crystalline olefin-based resin. The term "low-crystalline" means that the crystallinity is 10.5% or less, and can be measured by the following method. When the first fiber layer contains a low-crystalline olefin-based resin, the first fiber layer itself becomes more stretchable. When the first fiber layer contains a low-crystalline olefin-based resin, the mass proportion of the low-crystalline olefin-based resin in the first fiber layer is preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, even more preferably 92 mass% or more, and even more preferably 94 mass% or more.

[0051] (Method for determining whether the first fiber layer contains a low-crystalline olefin-based resin) The resin composition constituting the first fiber layer is subjected to various analyses such as NMR analysis and IR analysis. Based on the positions of the signals and spectra obtained by these analyses, the molecular skeleton structure and the functional group structure at the terminals of the molecular structure are identified. This allows the type of resin contained to be identified and specified. Next, crystallinity is measured using differential scanning calorimetry. The total heat of fusion obtained when the resin composition is heated is divided by the heat of fusion of a completely crystalline resin. If this value is less than 10.5%, it is determined that the resin contains a low-crystalline olefin-based resin.

[0052] Specific examples of the above-mentioned identical material include the following, from the viewpoint of enhancing the integrity of the first fiber layer and the second fiber layer and enhancing the stretchability of the fiber laminated sheet of the present invention. That is, examples of olefin-based resins include polypropylene (hereinafter referred to as PP) and polyethylene. Examples of low-crystalline olefin resins include α-olefins, such as polypropylene with controlled stereoregularity (polypropylene polymerized with controlled stereoregularity using a metallocene catalyst). Examples of the diene resin include polybutadiene and polyisoprene. The urethane resin may be polyurethane. Copolymers of olefin-based resins, diene-based resins, and urethane-based resins include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-octene copolymers, propylene-1-butene copolymers, propylene-1-octene copolymers, ethylene-isoprene copolymers, ethylene-butadiene copolymers, propylene-isoprene copolymers, propylene-butadiene copolymers, ethylene-propylene-isoprene copolymers, and ethylene-propylene-butadiene copolymers.

[0053] In the fiber laminated sheet of the present invention, from the viewpoint of further increasing the capillary force and further increasing the strength, the basis weight of the first fiber layer is 1 g / m 2 More than 1.5g / m is preferable. 2 More preferably, 2 g / m 2 The above is more preferable. In order to further improve the softness and adhesion to the skin surface, the basis weight of the first fiber layer is 8 g / m 2 Less than 6g / m is preferred 2 Less than 5g / m is more preferable. 2 By setting the median fiber diameter to this upper limit or less, the number of fibers having the aforementioned median fiber diameter per unit area in the first fiber layer is reduced, and the number of fiber voids is also reduced, thereby suppressing light scattering due to the presence of the fiber voids and making the first fiber layer more transparent.

[0054] In the fiber laminated sheet of the present invention, from the viewpoint of further strengthening the strength of the entire fiber laminated sheet and further increasing resistance to tearing and abrasion, the basis weight of the second fiber layer is 8 g / m 2 More than 15g / m is preferable. 2 More preferably, 20 g / m 2 The above is more preferable. In addition, in order to ensure the softness of the first fiber layer and its adhesion to the skin surface, the basis weight of the second fiber layer is 50 g / m 2 Preferably less than 40 g / m 2 Less than 30 g / m is more preferable. 2 By setting the diameter to this upper limit or less, the number of fibers having the above-mentioned median fiber diameter per unit area in the second fiber layer is reduced, making the layer more likely to bend.

[0055] The fiber laminate sheet of the present invention can be used to form various textile products. For example, the fiber laminate sheet of the present invention can be used to form adhesive bandages, dressings, cylindrical objects, gloves, face masks, and the like that are used by contacting the skin surface. Specific examples of the cylindrical objects include supports and finger cots.

[0056] The T-peel strength of a test piece taken from the textile product is preferably 0.2 N / 20 mm or more, more preferably 0.3 N / 20 mm or more, and even more preferably 0.4 N / 20 mm or more. This allows the textile layer to be used without peeling off even when subjected to friction or other abrasion when applied to the skin, etc. The higher the T-peel strength, the better. The T-peel strength in this case can be measured using the method described above (Method for Measuring T-peel Strength). Specifically, a test piece 20 mm wide and 80 mm long is prepared by cutting out a textile product. An adhesive tape (width: 20 mm, adhesive strength: 3.9 N / 10 mm) is applied to the surface of the first fiber layer, and the overlap length between the first fiber layer and the tape is set to 50 mm or more in the longitudinal direction. The tape end (one longitudinal end) and the fiber laminated sheet (the same longitudinal end as the tape end) are pulled with a gripping distance of 20 mm and a pulling speed of 100 mm / min, and the test force at which the tape peels from the fiber laminated sheet is measured. The average of the test forces obtained when the gripper travels a distance of 30 mm to 60 mm from the initial position is taken as the T-peel strength of the fiber laminated sheet.

[0057] In the raw web of the fiber laminated sheet of the present invention, i.e., a long rolled sheet, the T-peel strength of 10 test pieces taken evenly across the width of the roll, perpendicular to the circumferential direction of the roll, is preferably 0.5 N / 50 mm or more, more preferably 1 N / 50 mm or more, and even more preferably 1.5 N / 50 mm or more for all test pieces. This allows the sheet to be unwound from the raw web and used without peeling off the fiber layer even when subjected to friction and other abrasions when processed into various product forms. The higher the T-peel strength, the better. The T-peel strength in this case can be measured using the method described above (Method for Measuring T-peel Strength). Specifically, test pieces are prepared by unwinding a sheet from its original roll and cutting each end 10 mm apart. Fourteen pieces of adhesive tape (50 mm wide, adhesive strength: 3.9 N / 10 mm) are then attached to the surface of the first fiber layer of the fiber laminate sheet from one end in the width direction, resulting in fourteen test pieces measuring 50 mm wide and 150 mm long. The overlap length between the first fiber layer and the tape in the longitudinal direction is 100 mm or more. The tape end on the longitudinal side is then peeled off, and the tape end (one end in the longitudinal direction) and the fiber laminate sheet (the other end in the same longitudinal direction as the tape end) are gripped and pulled at a distance of 50 mm and a pulling speed of 100 mm / min, and the test force at which the tape peels from the fiber laminate sheet is measured. Of the test forces obtained, the average value of the test forces where the gripper traveled a distance of 30 mm or more and 130 mm or less from the initial position was taken as the T-peel strength of the fiber laminated sheet. [Example]

[0058] The present invention will be described in more detail below based on examples, but the present invention should not be construed as being limited thereto. In the examples, "parts" and "%" expressing mass are all based on mass unless otherwise specified.

[0059] Example 1 The method for producing the fiber laminated sheet of Example 1 was carried out as follows. The resin raw material is PP, and the spunbond method is used to create a fabric with a median fiber diameter of 15 μm and a basis weight of 24 g / m 2 The second fiber layer (support sheet) was formed. The second fiber layer had a width of 900 mm and a length of 1500 mm. A molten resin was prepared using PP (a low-crystalline resin raw material), and the resin was spun onto a support sheet by electrospinning using a spinning apparatus 10A shown in Figure 2. Thirty-two nozzles were arranged, eight in the width direction of the support sheet with a nozzle spacing of 100 mm, in four rows in the flow direction. The dynamic viscoelasticity curve of the molten resin is shown in FIG. 4, and the temperature Tc was 72°C. The linear distance from the nozzle tip to the surface of the support sheet was 300 mm. The position where the hot air and gas flow merged was as shown in Table 1, which was the midpoint of the linear distance from the nozzle tip to the surface of the support sheet. In addition, in order to set the space temperatures T1, T2 and T3 as shown in Table 1, gas flow and hot air were ejected into the space with a linear distance of 300 mm under the following conditions. The temperature of the gas flow was 280° C., the flow rate of the gas flow was 70 L / min, the temperature of the hot air was 200° C., and the flow rate of the hot air was 150 L / min. This allowed for the control of temperature changes in spaces S1, S2, and S3 as shown in Figure 7. The space temperature T3 at position S3, 25 mm in front of the support sheet surface, was maintained at a temperature higher than (Tc - 10°C): 72°C - 10°C = 62°C. Using the above manufacturing method, a fiber laminated sheet sample was produced in which the first fiber layer (ultrafine fiber layer) and the second fiber layer (support sheet) were integrated. In the fiber laminated sheet sample in Example 1, the first fiber layer was formed on the entire surface of the second fiber layer, the median fiber diameter of the first fiber layer was 0.9 μm, and the basis weight was 5 g / m 2 It was. The prepared fiber laminated sheet sample had the same dimensions as the second fiber layer, 720 mm in width and 1500 mm in length.

[0060] (Comparative Example 1) A fiber laminated sheet manufacturing method was carried out in the same manner as in Example 1, except that the hot air spraying unit 50 was not provided in the spinning apparatus 10A shown in Fig. 2 and hot air was not sprayed. In this way, a fiber laminated sheet sample in Comparative Example 1 was produced. The space temperatures T1, T2, and T3 were as shown in Table 1. The space temperature T3 at position S3, 25 mm in front of the surface of the support sheet, was below the temperature (Tc - 10°C): 72°C - 10°C = 62°C. The thinned resin lost its fluidity when it reached the surface of the support sheet and became rubbery fibers.

[0061] The fiber laminated sheet samples obtained by carrying out the fiber laminated sheet manufacturing methods of Example 1 and Comparative Example 1 were subjected to the abrasion resistance test (the T-peel strength measurement method) described above. The "maximum value," "average value," and "minimum value" shown in Table 1 indicate the maximum value and the minimum value, respectively, of the T-peel strength in the sheet width direction. The average value was the average of all measurement points. The results are shown in Table 1. The distribution of T-peel strength in the sheet width direction is shown in FIG.

[0062] [Table 1]

[0063] As shown in Table 1 and Fig. 10, the maximum, average, and minimum values ​​of the T-peel strength in the sheet width direction of the fiber laminated sheet sample obtained by carrying out the fiber laminated sheet manufacturing method of Example 1 were all higher than those of the fiber laminated sheet sample obtained by carrying out the fiber laminated sheet manufacturing method of Comparative Example 1. Furthermore, the fiber laminated sheet of Comparative Example 1 had holes with a diameter of about 20 mm in the T-peel strength test, as shown in Fig. 11, whereas the fiber laminated sheet of Example 1 showed no tears. This demonstrates that the method for producing a fiber laminated sheet of the present invention makes it possible to produce a fiber laminated sheet having excellent abrasion resistance. [Explanation of symbols]

[0064] 1 Support sheet 2. Ultra-fine fiber layer M First fiber layer N Second fiber layer 100 Fiber laminated sheet

Claims

1. a spinning step of spinning and laminating fibers having a fiber diameter of 0.3 μm or more and 5 μm or less on a support sheet, the spinning step is a step of discharging a molten resin from a nozzle and stretching the molten resin into fibers by a gas flow that is jetted along the direction of the discharge at the side of the nozzle, In the spinning step, In the space from the tip of the nozzle to the support sheet, (1) The space temperature T1 at a position 50 mm from the tip of the nozzle is set to 80°C or more and 180°C or less, and the space temperature T2 at a position 100 mm from the tip of the nozzle is set to 40°C or more and 120°C or less, (2) The space temperature T3 at a position 25 mm in front of the surface of the support sheet is set to be higher than the temperature Tc (Tc-10°C) below. A heat treatment is performed on the space, In the dynamic viscoelasticity curve obtained by cooling the molten resin from a molten state at 200°C at a temperature decreasing rate of 4°C / min, the temperature Tc at which the storage modulus (G') and the loss modulus (G'') intersect is 30°C or higher and 80°C or lower. A method for manufacturing a fiber laminated sheet.

2. The heat treatment includes blowing hot air, The method for producing a fiber laminated sheet according to claim 1 , wherein the hot air meets the gas flow on the support sheet side of a middle position in a linear distance from the tip of the nozzle to the surface of the support sheet.

3. In the space from the 50 mm position to the 100 mm position, the space temperature is reduced from the temperature T1 range to the temperature T2 range; The method for producing a fiber laminated sheet according to claim 1 or 2, wherein the temperature is maintained at or above the temperature (Tc-10°C) from the 100 mm position to the surface of the support sheet.

4. The reduction in space temperature in the space from the 50 mm position to the 100 mm position is controlled by the gas flow; The method for producing a fiber laminated sheet according to claim 3, wherein the temperature in the space from the 100 mm position to the surface of the support sheet is maintained by controlling the gas flow and / or the hot air.

5. A fiber laminated sheet having a first fiber layer having a median fiber diameter of 0.3 μm or more and 5 μm or less and a second fiber layer adjacent thereto having a median fiber diameter of 5 μm or more and 50 μm or less, the first fiber layer and the second fiber layer contain the same material, and the same material is selected from an olefin resin, a diene resin, a urethane resin, and a copolymer thereof; the first fiber layer and the second fiber layer are integrated by fusion-bonded intersections of the fibers of each layer, A fiber laminated sheet, wherein the laminated sheet has a T-peel strength of 0.5 N / 50 mm or more.

6. A textile product comprising the fiber laminate sheet according to claim 5.

7. 7. The textile product according to claim 6, wherein a test piece taken from the textile product has a T-peel strength of 0.2 N / 20 mm or more.

8. A raw fiber laminated sheet as described in claim 5, wherein the raw fiber laminated sheet is a long roll of the fiber laminated sheet, and the T-peel strength of 10 test pieces taken evenly in the width direction perpendicular to the circumferential direction of the roll is 0.5 N / 50 mm or more for all test pieces.

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