stretchable fiber sheet

Abstract

To provide a stretchable fiber sheet capable of being easily used in various industrial use thanks to stretchability and excellent rigidity thereof.SOLUTION: A stretchable fiber sheet 100 has a fiber layer 11 including crimped fibers. The fiber layer has a plurality of fiber fixed parts 12 on a principal surface. The stretchable fiber sheet satisfies following constitutions: when a straight line passing on the principal surface is plotted on the principal surface of the fiber layer constituting the stretchable fiber sheet, the straight line has intersections with the plurality of fiber fixed parts; and length of the shortest distance between the fiber fixed parts that exist on the principal surface and are adjacent to each other is equal to or shorter than apparent fiber length of the crimped fiber.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This invention relates to an elastic fiber sheet. [Background technology]

[0002] In recent years, stretchable fiber sheets (hereinafter referred to as stretchable fiber sheets) have been used to improve conformability to the body. For example, stretchable fiber sheets are used in a variety of industrial applications, such as around the waist and groin of diapers, in supporters and bandages, in adhesive medicinal bases and plaster bases, and in medical and hygiene products such as facial masks.

[0003] As an example of such an elastic fiber sheet, Japanese Patent Application Publication No. 2021-094072 (Patent Document 1) discloses an elastic fiber sheet (10) having a plurality of fiber fixing portions (2) that pass through the fiber layer and exist continuously in a direction (B) perpendicular to one direction (A), as shown in Figure 1. The invention described in Patent Document 1 is characterized by providing an elastic fiber sheet (10) with excellent tensile strength in the one direction (A) by making the shortest distance (C) between adjacent fiber fixing portions (2) less than or equal to the apparent fiber length of the crimped fiber.

[0004] Furthermore, Japanese Patent Publication No. 59-137552 (Patent Document 2) discloses a highly strong nonwoven fabric made by heat-pressing a web consisting of a fiber mixture containing crimped fibers as constituent fibers with an embossing roll. Patent Document 2 discloses that the embossing pattern shown in Figure 2 was adopted as the pattern in which the constituent fibers of the web containing crimped fibers are heat-pressed by the embossing roll. It should be noted that Patent Document 2 is not an invention that examines the spacing between embossings, and does not disclose or suggest the length (distance) between such embossings. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2021-094072 [Patent Document 2] Japanese Patent Publication No. 59-137552 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, as a result of further consideration by the applicant, it was found that conventional stretchable fiber sheets, such as those disclosed in Patent Document 1 and Patent Document 2, still sometimes have inferior rigidity, for example, low tensile strength in the MD and CD directions, low strength at 20% elongation, and low strength at 50% elongation, making them difficult to use in various industrial applications. [Means for solving the problem]

[0007] The present invention "(Claim 1) An elastic fiber sheet comprising a fiber layer containing crimped fibers, The constituent fibers of the aforementioned fiber layer are short fibers cut to a specific length. The aforementioned fiber layer is on the main surface The same shape It has multiple fiber fixing parts, Each of the aforementioned fiber fixing portions, having the same shape, is distributed and located on the main surface of the fiber layer, on an oblique grid or at the intersections of the grid. When a straight line is drawn on the main surface passing through it, the straight line has multiple points of intersection with the fiber fixing portions. The shortest distance between adjacent fiber fixing portions on the main surface is 10 mm or more. The shortest distance between adjacent fiber fixing portions on the main surface is less than or equal to the apparent fiber length of the crimped fiber. A stretchable fiber sheet. That is the case. [Effects of the Invention]

[0008] As a result of further consideration by the applicant, in an elastic fiber sheet having a fiber layer containing crimped fibers, wherein the fiber layer has a plurality of fiber fixing portions on its main surface, When a straight line is drawn on the main surface of the fiber layer constituting the stretchable fiber sheet, and the straight line intersects with multiple fiber fixing portions, The shortest distance between adjacent fiber fixing portions on the main surface is less than or equal to the apparent fiber length of the crimped fiber. We found that a stretchable fiber sheet that satisfies both of these conditions exhibits excellent rigidity.

[0009] The reason for this has not been fully determined, but the following reasons are possible. 1. On the main surface of the fiber layer constituting the stretchable fiber sheet, areas without fiber fixing portions differ from fiber fixing portions where the constituent fibers are integrated together. When the stretchable fiber sheet is stretched (subjected to tension), the entanglement between the constituent fibers easily untangles, resulting in areas with inferior rigidity. Therefore, an elastic fiber sheet that can draw a straight line passing through its main surface without intersecting with the fiber fixing portion on the main surface is considered to have a portion on its main surface where the entanglement between constituent fibers can be easily undone in a straight line.

[0010] Specifically, in the stretchable fiber sheet disclosed in Patent Document 1, when a straight line is drawn passing through the main surface in a direction perpendicular to the aforementioned one direction, it is possible to draw a straight line that does not intersect with multiple fiber fixing portions. Therefore, it is considered that the stretchable fiber sheet disclosed in Patent Document 1 has portions in the aforementioned straight line where the entanglement of constituent fibers can be easily untangled.

[0011] 2. In portions where the shortest distance between adjacent fiber-fixing portions on the main surface is longer than the apparent fiber length of the crimped fibers contained in the fiber layer, theoretically, there are no crimped fibers connecting adjacent fiber-fixing portions. Therefore, in an elastic fiber sheet where the shortest distance between adjacent fiber-fixing portions on the main surface is longer than the apparent fiber length of the crimped fiber, it is considered that there are portions between adjacent fiber-fixing portions where the entanglement of constituent fibers can be easily undone.

[0012] Specifically, the invention according to Patent Document 2 does not consider the length (distance) between adjacent embossments existing on the main surface of the web. Therefore, when the length (distance) is longer than the apparent fiber length of only the crimped fibers constituting the web, it is considered that there is a portion where the entanglement between the constituent fibers is likely to be released between adjacent embossments.

[0013] From the above, the stretchable fiber sheet having the configurations of 1. and 2. described above is considered to be a stretchable fiber sheet inferior in rigidity in the MD direction and the CD direction because it has a portion where the entanglement between the straight constituent fibers is likely to be released passing through the main surface.

[0014] On the other hand, the stretchable fiber sheet having the configuration according to the present invention 3. When a straight line passing through the main surface is drawn on the main surface of the fiber layer constituting the stretchable fiber sheet, the straight line has intersections with the plurality of fiber fixing portions. Therefore, it does not have a portion where the entanglement between the straight constituent fibers is likely to be released passing through the main surface. Also, 4. Since the length of the shortest distance between adjacent fiber fixing portions existing on the main surface is equal to or less than the apparent fiber length of the crimped fibers, theoretically, there are crimped fibers connecting adjacent fiber fixing portions. Therefore, it is prevented that the portion between adjacent fiber fixing portions becomes a portion where the entanglement between the constituent fibers is likely to be released.

[0015] From the above, the stretchable fiber sheet according to the present invention having the configurations of 3. and 4. described above is considered to be excellent in rigidity in the MD direction and the CD direction.

[0016] Furthermore, in the stretchable fiber sheet according to the present invention, when the shapes of the plurality of fiber fixing portions are the same, the physical properties of the stretchable fiber sheet are uniformly improved as a whole.

[0017] Therefore, the stretchable fiber sheet according to the present invention is considered to be further excellent in rigidity.

Brief Description of the Drawings

[0018] [Figure 1] This is a schematic plan view of the stretchable fiber sheet disclosed in Patent Document 1, as seen from the main surface side. [Figure 2] This is a schematic plan view of the stretchable fiber sheet disclosed in Patent Document 2, as seen from the main surface side. [Figure 3] This is a schematic plan view of the stretchable fiber sheet prepared in Comparative Example 1, as seen from the main surface side. [Figure 4] This is a schematic plan view of the stretchable fiber sheet prepared in Comparative Example 2, as seen from the main surface side. [Figure 5] This is a schematic plan view of the stretchable fiber sheet prepared in Comparative Example 3, as seen from the main surface side. [Figure 6] This is a schematic plan view of the stretchable fiber sheet prepared in Example 1, as seen from the main surface side. [Modes for carrying out the invention]

[0019] In this invention, various configurations can be appropriately selected, such as the following configuration. Unless otherwise specified, the various measurements described in this invention were performed under normal pressure and a temperature of 25°C. Unless otherwise specified, the various measurement results described in this invention were obtained by measuring to a value one decimal place smaller than the desired value, and then rounding that value to calculate the desired value. As a specific example, if the desired value is to be expressed to the first decimal place, the value was measured to the second decimal place, and the obtained second decimal place value was rounded to calculate the value to the first decimal place, which was then used as the desired value.

[0020] Furthermore, the upper and lower limits exemplified in this invention can be combined in any way. The stretchable fiber sheet of the present invention will be described primarily with reference to Figure 6.

[0021] The stretchable fiber sheet (100) of the present invention comprises a fiber layer (11) containing crimped fibers and a plurality of fiber fixing portions (12) on the main surface of the fiber layer (11) that fix the constituent fibers together. The fiber layer (11) primarily plays a role in maintaining the shape of the stretchable fiber sheet (100) and in providing the stretchable fiber sheet (100) with elasticity.

[0022] The fiber layer (11) contains crimped fibers as constituent fibers. The crimped fibers referred to here are, for example, fibers having crimp or fibers in which crimp has been expressed from latent crimped fibers (for example, fibers in which crimp has been expressed from composite fibers such as core-sheath type, sea-island type, side-by-side type, orange type, etc.), and the fiber layer (11) is highly elastic due to the inclusion of crimped fibers. The percentage of the mass of crimped fibers in relation to the mass of constituent fibers in the fiber layer (11) is adjusted as appropriate, but it is preferably 30% by mass or more, preferably 40% by mass or more, preferably 50% by mass or more, preferably 60% by mass or more, preferably 70% by mass or more, preferably 80% by mass or more, preferably 90% by mass or more, in order to provide an elastic fiber sheet (100) with greater elasticity, and it is more preferable that the constituent fibers of the fiber layer (11) consist only of crimped fibers.

[0023] The fiber layer (11) may contain other fibers besides the crimped fibers described above, such as monofilaments and adhesive fibers (fully melt-type adhesive fibers, or partially melt-type adhesive fibers such as core-sheath type, sea-island type, side-by-side type, orange type, bimetal type, etc.). These fibers other than crimped fibers can be made of the same resin as the crimped fibers, and their fiber length and fineness can be the same as those of the crimped fibers.

[0024] The polymers that make up the constituent fibers of the fiber layer (11) can be appropriately selected, for example, polyolefin resins (polyethylene, polypropylene, polymethylpentene which makes up the fibers that constitute the crimped fibers, polyolefin resins with a structure in which some of the hydrocarbons are replaced with cyano groups or halogens such as fluorine or chlorine), styrene resins, polyether resins (polyetherether ketone, polyacetal, phenolic resins, melamine resins, urea resins, epoxy resins, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, fully aromatic poly Known polymers can be used, such as ester resins, unsaturated polyester resins, polyimide resins, polyamide-imide resins, polyamide resins (e.g., aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having nitrile groups (e.g., polyacrylonitrile), urethane resins, epoxy resins, polysulfone resins (e.g., polysulfone, polyethersulfone, etc.), fluororesins (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, and acrylic resins (e.g., polyacrylonitrile resins copolymerized with acrylic acid esters or methacrylic acid esters, modacrylic resins copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.).

[0025] These polymers may consist of either linear or branched polymers, and may be block copolymers or random copolymers. Furthermore, the three-dimensional structure and crystalline nature of the polymers may be anything. In addition, the polymer may contain multiple polymers, or a mixed polymer formed by mixing multiple polymers.

[0026] As will be described in detail later, among these exemplified polymers, it is preferable that the constituent fibers of the fiber layer (11) are made of thermoplastic resins such as polyolefin resins or polyester resins, so that a fiber fixing portion (12) can be easily formed by heat-fusing the constituent fibers of the fiber layer (11). In addition, it is even more preferable that the stretchable fiber sheet (100) has a fiber layer (11) whose constituent fibers are made of polypropylene resin or polyester resin only (more preferably polyester resin only), as it has the characteristic of being less likely to adsorb drugs.

[0027] The constituent fibers of the fiber layer (11) may have irregular cross-sectional shapes in addition to having a roughly circular or elliptical cross-sectional shape. Examples of irregular cross-sectional fiber shapes include hollow shapes, polygonal shapes such as triangular shapes, alphabetic shapes such as Y shapes, irregular shapes, multi-lobed shapes, symbolic shapes such as asterisk shapes, or shapes formed by combining multiple of these shapes.

[0028] The fiber length of the constituent fibers of the fiber layer (11) can be appropriately selected and may be short fibers or long fibers cut to a specific length, or continuous fibers (such as fibers not cut to a specific length prepared using the direct spinning method). However, it is preferable that the fibers be cut to a specific length in order to provide an elastic fiber sheet (100) with excellent elasticity. The fiber length can be 5 to 150 mm, 10 to 100 mm, 30 to 90 mm, or 40 to 80 mm. Note that "fiber length" refers to the fiber length measured in accordance with JIS L1015 (2010), 8.4.1c Direct method (Method C).

[0029] The fineness of the constituent fibers of the fiber layer (11) can be appropriately selected to provide an elastic fiber sheet (100) with excellent elasticity, for example, it can be 0.01 to 100 dtex, 0.1 to 50 dtex, 0.5 to 30 dtex, or 1 to 10 dtex.

[0030] The fiber layer (11) can be a layer derived from a fabric such as a fiber web or nonwoven fabric. The fibers constituting the fiber layer (11) can be obtained by known methods such as melt spinning, dry spinning, wet spinning, a method of extracting fine fibers by removing one or more resin components from composite fibers, or a method of obtaining divided fibers by beating fibers.

[0031] If the fabric is a nonwoven fabric, a dry method, a wet method, or the like can be used as a method for preparing a fiber web capable of producing a nonwoven fabric. Methods for entangling and / or integrating the fibers constituting the fiber web to form a nonwoven fabric include, for example, entangling with needles or a water stream, integrating the fibers with a binder, or, if the fiber web contains a thermoplastic resin, melting the thermoplastic resin by heat-treating the fiber web to integrate the fibers. The binder for integrating the fibers can be selected from the polymers mentioned above. Methods for heat-treating the fiber web include, for example, heating and pressurizing with a calender roll, heating with a hot air dryer, or irradiating with infrared radiation under no pressure.

[0032] The fiber layer (11) may have a binder to bond and integrate the constituent fibers together, and / or to support the functional components described later on the constituent fibers. However, it is preferable that there is no binder other than the constituent fibers, in order to prevent unintended reactions with the drug, reduce skin irritation, and provide a more elastic fiber sheet (100) with superior elasticity. From this viewpoint, it is preferable that the fiber layer (11) is a nonwoven fabric in which the constituent fibers are entangled and integrated by needles or water flow.

[0033] The fiber layer (11) may also contain functional components. The type of functional component is not limited, as it can be appropriately selected depending on the required function, but examples include antibacterial agents, disinfectants, antiviral agents, antifungal agents, catalysts (e.g., titanium dioxide, manganese dioxide, or platinum-supported alumina), humidity control agents (e.g., silica gel or silica microcapsules), deodorizers such as activated carbon or carbon black, pigments, fragrances, cation exchange resins or anion exchange resins, and cosmetic ingredients.

[0034] The functional component can exist as particulate matter on and / or inside the constituent fibers of the fiber layer (11), or as a film covering part or all of the surface of the fiber layer (11). The method for supporting the functional component on the fiber layer (11) can be appropriately selected, but for example, a method can be employed in which a dispersion of the functional component, or a dispersion of the functional component containing a binder, is supported on one or both main surfaces of the fiber layer (11) by spraying or a known coating method (e.g., a kiss coating method using a gravure roll, a die coating method, etc.), and then the solvent is removed, or a method can be employed in which the fiber layer (11) is immersed in the above-mentioned dispersion and then removed, and then the solvent is removed.

[0035] The composition and physical properties of the fiber layer (11), such as basis weight and thickness, can be adjusted as appropriate, but the basis weight is 5 to 1000 g / m². 2 It can be 10-500g / m² 2 It can be 20-200g / m 2 It can be 30-100g / m 2 It can be such that the thickness can be 0.05 to 5 mm, 0.1 to 3 mm, or 0.5 to 2 mm. In this invention, "basis weight" refers to the area of ​​the main surface per 1 m². 2 This refers to the mass per unit area, and the main surface refers to the surface with the largest area. Furthermore, the "thickness" as used in this invention is a value measured using a high-precision digital measuring instrument (Lightmatic® manufactured by Mitutoyo Corporation), specifically measured 5 cm from the main surface of the object being measured. 2This refers to the thickness value in the load region when a load of 100 gf is applied to that region.

[0036] The stretchable fiber sheet (100) according to the present invention has a plurality of fiber fixing portions (12) on the main surface of the fiber layer (11).

[0037] The fiber fixing portion (12) is a portion in which the constituent fibers of the fiber layer (11) containing crimped fibers are integrated with each other. For example, it can be a portion in which the constituent fibers of the fiber layer (11) are bonded together by a binder, a portion in which the constituent fibers of the fiber layer (11) are heat-fused and melted together, or a portion in which the constituent fibers are softened without melting and then compressed and integrated together.

[0038] Furthermore, the individual fiber fixing portions (12) on the main surface of the fiber layer (11) are not connected to each other. In other words, there are no portions between the individual fiber fixing portions (12) on the main surface of the fiber layer (11) where the constituent fibers of the fiber layer (11), including the crimped fibers, are integrated, as described above.

[0039] Therefore, since each fiber fixing portion (12) is not connected to one another, the elasticity of the fiber layer (11) is not easily hindered, resulting in a highly stretchable fiber sheet (100).

[0040] In order for the constituent fibers of the fiber layer (11) to be more integrated, it is preferable that in the fiber fixing portion (12), there are portions where the constituent fibers are integrated not only on the main surface of the fiber layer (11) but also in the thickness direction of the fiber layer (11), and it is even more preferable that there are portions where the constituent fibers are integrated along the entire thickness direction of the fiber layer (11), from one main surface to the other.

[0041] The shape of each fiber fixing portion (12) is adjusted as appropriate to provide the stretchable fiber sheet (100) according to the present invention. For example, the shape of each fiber fixing portion (12) can be a leather-like texture, a dotted shape, an irregular shape, a linear shape such as a straight line or a curve, a line segment shape, a dashed line shape, a polygonal shape, an illustration of an animal or character, an alphabet or symbol shape, or a shape that combines these shapes.

[0042] The size of the fiber fixing portion (12) can be adjusted as appropriate. Furthermore, if the fiber fixing portion (12) is linear, linear, or dashed, the thickness of the line can also be adjusted as appropriate. To provide a highly elastic fiber sheet (100) with excellent elasticity, the line thickness is preferably thin, preferably 3 mm or less, preferably 2 mm or less, and preferably 1 mm or less. On the other hand, a lower limit of 0.05 mm or more is practical.

[0043] In particular, in order to provide an elastic fiber sheet (100) with excellent elasticity and rigidity by making the physical properties of the elastic fiber sheet (100) uniform overall, it is preferable that each fiber fixing portion (12, each fiber fixing portion (12) whose entire shape can be seen without interruption) present on the main surface of the fiber layer (11) is identical in shape (all fiber fixing portions (12) are the same size and coincide when translated).

[0044] For example, the embossed pattern applied to the nonwoven fabric disclosed in Patent Document 2, shown in Figure 2, comprises at least two types of embossing with different orientations. Therefore, in an elastic fiber sheet having multiple fiber fixing portions in this manner, the shape of each fiber fixing portion present on the main surface of the fiber layer is not identical.

[0045] Furthermore, the distribution of each fiber fixing portion (12) present on the main surface of the fiber layer (11) is appropriately adjusted to provide the stretchable fiber sheet (100) according to the present invention. In particular, in order to provide a stretchable fiber sheet (100) with excellent elasticity and rigidity by making the physical properties of the stretchable fiber sheet (100) uniform overall, it is preferable that each fiber fixing portion (12) present on the main surface of the fiber layer (11) is distributed at equal intervals. Examples of such arrangements include a configuration in which each fiber fixing portion (12) is distributed and present on an oblique grid or at the intersections of a grid.

[0046] An example of an elastic fiber sheet (100) having the fiber fixing portion (12) described above is the elastic fiber sheet (100) prepared in Example 1.

[0047] In the present invention, when a straight line passing through the main surface is drawn on the main surface of the fiber layer (11) constituting the stretchable fiber sheet (100), the straight line intersects with a plurality of fiber fixing portions (12). Whether or not the stretchable fiber sheet (100) satisfies this configuration can be determined by the following method.

[0048] 1. Obtain a fiber layer (11) having fiber fixing portions (12) on its main surface from an elastic fiber sheet (100), and take a square-shaped sample with sides of 15 cm from the obtained fiber layer (11). At this time, take the sample so that multiple fiber fixing portions (12) are present on the main surface. 2. Take a micrograph of the entire main surface of the sample on the side with the fiber-fixed portion (12). Alternatively, a micrograph of the entire main surface may be created by combining multiple micrographs. 3. Draw multiple straight lines on the microscope image that pass through the main surface of the fiber layer (11). Each line should be drawn so that it passes through two parallel sides of the sample when viewed from the main surface side. 4. If any of the drawn straight lines intersect with multiple fiber fixing portions (12), it is determined that the stretchable fiber sheet (100) from which the sample was taken has a fiber layer (11) that satisfies the configuration that "when a straight line is drawn on the main surface passing through the main surface, the straight line intersects with multiple fiber fixing portions (12)." On the other hand, if any of the drawn lines do not intersect with multiple fiber fixing portions (12) (for example, if there is a line that may have an intersection, or if there is a line that has only one intersection), then the stretchable fiber sheet (100) from which the sample was taken is judged not to satisfy the above-described configuration.

[0049] The stretchable fiber sheet (100) according to the present invention has a fiber layer (11) that satisfies the above-described structure, and therefore does not have a portion on the main surface of the fiber layer (11) where the entanglement between constituent fibers is easily undone in a straight line, thus having excellent rigidity.

[0050] In the present invention, the shortest distance between adjacent fiber fixing portions (12) on the main surface of the fiber layer (11) is less than or equal to the apparent fiber length of the crimped fiber. The "apparent fiber length of the crimped fiber" referred to here is the length (distance) measured by the method described below (Method for measuring the apparent fiber length of the crimped fiber). Furthermore, the apparent fiber length of the crimped fiber is less than or equal to the fiber length of the crimped fiber.

[0051] (Method for measuring the apparent fiber length of crimped fibers) 1. Take a microscopic photograph of the stretchable fiber sheet (10) or the fiber layer (11) constituting the stretchable fiber sheet (10), showing the entire crimped fiber. 2. Select one crimped fiber from the microscope image, draw a straight line on the microscope image that has two or more intersections with the crimped fiber, and draw the longest possible line segment on the straight line with the intersections as its ends. If the crimped fiber is in contact with the fiber fixing portion (2), the point of contact between the crimped fiber and the fiber fixing portion (2) shall be the end of the line segment being drawn. 3. Perform methods 1 and 2 described above on 30 or more crimped fibers, and draw line segments on each in the same manner. 4. Of the lengths of the 30 line segments drawn, the longest value is determined to be the "apparent fiber length of the crimped fiber."

[0052] The apparent fiber length of the crimped fibers can be appropriately selected, but the longer the length, the easier it is to provide an elastic fiber sheet (100) with excellent elasticity. Therefore, the apparent fiber length of the crimped fibers is preferably 5 mm or more, preferably 10 mm or more, preferably 20 mm or more, and preferably 30 mm or more. On the other hand, the upper limit can also be appropriately selected, but it is practical to keep it at 100 mm or less.

[0053] The shortest distance between adjacent fiber fixing portions (12) on the main surface of the fiber layer (11) refers to the length measured by the method described below (Method for measuring the shortest distance).

[0054] (Method for measuring the shortest distance) 1. Obtain a fiber layer (11) having fiber fixing portions (12) on its main surface from an elastic fiber sheet (100), and take a square-shaped sample with sides of 15 cm from the obtained fiber layer (11). At this time, take the sample so that multiple fiber fixing portions (12) are present on the main surface. 2. Take a micrograph of the entire main surface of the sample on the side with the fiber-fixed portion (12). Alternatively, a micrograph of the entire main surface may be created by combining multiple micrographs. 3. On the microscope image, draw the shortest possible line segments connecting adjacent fiber-fixing portions (12) for each combination of adjacent fiber-fixing portions (12). 4. The length of the shortest line segment among the drawn line segments is determined to be the shortest distance between adjacent fiber fixing portions (12) on the main surface of the fiber layer (11).

[0055] The minimum distance between adjacent fiber fixing portions (12) on the main surface of the fiber layer (11) can be appropriately selected, but the longer the length, the easier it is to provide an elastic fiber sheet (100) with excellent elasticity. Therefore, the minimum distance is preferably 1 mm or more, preferably 3 mm or more, preferably 5 mm or more, preferably 10 mm or more, preferably 20 mm or more, and preferably 30 mm or more. On the other hand, the upper limit can also be appropriately selected, but it is practical to keep it at 100 mm or less.

[0056] The stretchable fiber sheet (100) according to the present invention has a fiber layer (11) that satisfies the above-described configuration, so that both ends of the crimped fibers constituting the fiber layer (11) can be fixed by adjacent fiber fixing portions (12). Therefore, in the stretchable fiber sheet (100) according to the embodiment of the present invention, theoretically, there are crimped fibers that connect adjacent fiber fixing portions (12). Therefore, the rigidity between adjacent fiber fixing portions (12) is also maintained by the strength of the crimped fibers (the crimped fibers that connect the adjacent fiber fixing portions (12)) themselves. As a result, even when the stretchable fiber sheet (100) is stretched (when subjected to tension), the area between adjacent fiber fixing portions (12) is prevented from becoming a part where the entanglement of the constituent fibers is easily undone.

[0057] The stretchable fiber sheet (100) according to the present invention may consist only of a fiber layer (11), but it may also have a structure in which other materials such as fabric or film (non-porous film or porous film) or foam (non-porous foam or porous foam) are laminated on the fiber layer (11). The method of laminating the fiber layer (11) and the other materials can be appropriately selected, and it may be simply laminated, bonded and integrated using a binder such as a powder binder, spray binder or hot melt web, or bonded and integrated by melting the constituent components such as adhesive fibers.

[0058] Furthermore, the materials, weight, thickness, and other configurations of the other components can be appropriately adjusted or selected to suit the requirements of the stretchable fiber sheet (100).

[0059] To prevent breakage when stretched in one direction, the tensile strength of the stretchable fiber sheet (100) is preferably greater than 0.4 N / 20 mm, preferably 0.5 N / 20 mm or more, preferably 0.6 N / 20 mm or more, preferably 1 N / 20 mm or more, preferably 3 N / 20 mm or more, and preferably 5 N / 20 mm or more. The tensile strength can be determined by the following measurement method.

[0060] (Method for measuring tensile strength (unit: N / 20mm)) A sample piece measuring 20 mm on the short side and 80 mm on the long side is taken from the object to be measured. When taking the sample piece, ensure that the long side is parallel to the production direction (MD direction) of the object to be measured. Then, using a constant-speed elongation tensile testing machine (Orientec Co., Ltd., Tensilon, distance between chucks (gripping distance): 50 mm, tensile speed: 100 mm / min), the sample piece is pulled in the direction of its long side, and the maximum load until the sample piece breaks is measured. If the sample piece has two or more fiber fixing parts, the sample piece is fixed to the chucks so that adjacent fiber fixing parts are present between the chucks. This maximum load measurement is performed on three sample pieces, and these maximum loads are arithmetic mean to obtain the "tensile strength" in the MD direction. A higher "tensile strength" indicates that the material is less likely to break during stretching and has superior rigidity.

[0061] Furthermore, by subjecting a sample piece taken so that the direction perpendicular to the production direction of the object to be measured (CD direction) and the direction of the long side are parallel to each other, to the above-mentioned measurement, the "tensile strength" in the CD direction can be determined.

[0062] Furthermore, by taking a sample piece such that the direction in which one diagonal of a square, formed by sides parallel to the MD and CD directions of the object to be measured, extends is parallel to the direction of the longer side, and then subjecting this sample piece to the above measurement, the "tensile strength" in the diagonal direction can be determined.

[0063] To ensure that the elastic fiber sheet (100) has excellent elasticity, the elongation rate of the elastic fiber sheet (100) is preferably 10% or more, preferably 50% or more, and preferably 100% or more. On the other hand, if the elongation rate is too high, the usability of the elastic fiber sheet (100) may be poor, so it is more practical to have an elongation rate of 500% or less. The elongation rate can be determined by the following measurement method.

[0064] (Method for measuring elongation rate (Sr, unit: %)) This refers to the percentage of the elongation of the sample piece at maximum load (Smax, in mm) [= (length at maximum load, in mm) - (grip spacing = 50 mm)] relative to the grip spacing (50 mm) when the tensile strength measurement described above was performed. In other words, it is the value obtained from the following formula. This measurement is performed three times, and the arithmetic mean of the above percentages is taken as the "elongation rate". Sr = (Smax / 50) × 100 Furthermore, a higher "elongation rate" indicates superior stretchability.

[0065] The elastic fiber sheet (100) is designed to provide excellent comfort when used in the gathers of diapers, a moderate level of compression when used as a base material for surgical tape, and excellent adhesion when used as a base material for adhesive patches. The various stretch strengths of the elastic fiber sheet (100) are adjusted accordingly. The stretch strength can be determined by the following measurement method.

[0066] (Measurement method for strength at 20% elongation and strength at 50% elongation (unit: N / 20mm)) A sample piece measuring 20 mm on the short side and 80 mm on the long side is taken from the object to be measured. When taking the sample piece, ensure that the long side is parallel to the production direction (MD direction) of the object to be measured. Next, a constant-speed elongation tensile testing machine (Tensilon, manufactured by Orientec Co., Ltd.) is used to fix the sample piece between the two chucks (distance between chucks (gripping interval): 50 mm). If the sample piece has two or more fiber fixing sections, the sample piece is fixed to the chucks so that adjacent fiber fixing sections are present between the chucks. Then, the two chucks are separated at a tensile speed of 100 mm / min, and the maximum stress shown in the sample piece when it is elongated by 10 mm (=20%) and the maximum stress shown in the sample piece when it is elongated by 25 mm (=50%) are measured. This measurement is performed on three sample pieces, and the arithmetic mean of these maximum stresses is taken to determine the "20% elongation strength" and "50% elongation strength" in the MD direction. Note that higher values ​​indicate greater rigidity.

[0067] Furthermore, by subjecting a sample piece taken so that the direction perpendicular to the production direction of the object to be measured (CD direction) and the long side direction are parallel to each other to the above measurement, the "strength at 20% elongation" and the "strength at 50% elongation" in the CD direction can be determined.

[0068] Furthermore, by taking a sample piece such that the direction in which one diagonal of a square extending parallel to the longer side is parallel to the direction in which the longer side extends, assuming a square composed of sides parallel to the MD and CD directions of the object to be measured, the "strength at 20% elongation" and "strength at 50% elongation" in the diagonal direction can be determined.

[0069] The recovery rate of the stretchable fiber sheet (100) during various stretches is adjusted so that it is a highly elastic stretchable fiber sheet (100). The recovery rate during stretching can be determined by the following measurement method.

[0070] (Method for measuring the recovery rate (in %) after 20% elongation) A sample piece measuring 20 mm on the short side and 80 mm on the long side is taken from the object to be measured. When taking the sample piece, ensure that the long side is parallel to the production direction (MD direction) of the object to be measured. Then, using a constant-speed elongation tensile testing machine (Tensilon, manufactured by Orientec Co., Ltd.), the sample piece is fixed between the two chucks (distance between chucks (gripping interval): 50 mm). If the sample piece has two or more fiber fixing portions, the sample piece is fixed to the chucks so that adjacent fiber fixing portions are both present between the chucks. Starting with a gripping distance of 50 mm, the sample is pulled at a speed of 100 mm / min to a position 10 mm from the starting point, i.e., the 20% elongation position (L20 = 10 mm), and then returned to the starting point at the same speed. The length obtained by subtracting the initial gripping distance (50 mm) from the gripping distance when the tensile stress of the sample becomes 0.05 N during this pulling process (Lf), and the length obtained by subtracting the initial gripping distance (50 mm) from the gripping distance when the tensile stress of the sample becomes 0.05 N during the return process (Lb) are measured. This measurement is performed on three sample pieces, and the average value of the gripping distance length (Lf) (Lf1) and the average value of the gripping distance length (Lb) (Lb1) are obtained by taking the arithmetic mean of the lengths. The value calculated from the following formula is defined as the "recovery rate at 20% elongation" in the MD direction. Recovery rate (%) when stretched by 20% = [[(L20-Lf1)―(Lb1-Lf1)] / (L20-Lf1)] × 100

[0071] Furthermore, by subjecting a sample taken so that the direction perpendicular to the production direction of the object to be measured (CD direction) and the long side direction are parallel to each other to the above measurement, the "recovery rate at 20% elongation" in the CD direction can be determined.

[0072] (Method for measuring the recovery rate (in %) at 50% elongation) A sample piece measuring 20 mm on the short side and 80 mm on the long side is taken from the object to be measured. When taking the sample piece, ensure that the long side is parallel to the production direction (MD direction) of the object to be measured. Then, using a constant-speed elongation tensile testing machine (Tensilon, manufactured by Orientec Co., Ltd.), the sample piece is fixed between the two chucks (distance between chucks (gripping interval): 50 mm). If the sample piece has two or more fiber fixing portions, the sample piece is fixed to the chucks so that adjacent fiber fixing portions are both present between the chucks. Starting with a gripping distance of 50 mm, the sample is pulled at a speed of 100 mm / min to a position 25 mm from the starting point, i.e., the 50% elongation position (L50 = 25 mm), and then returned to the starting point at the same speed. The length obtained by subtracting the initial gripping distance (50 mm) from the gripping distance when the tensile stress of the sample becomes 0.05 N during this pulling process (Lf), and the length obtained by subtracting the initial gripping distance (50 mm) from the gripping distance when the tensile stress of the sample becomes 0.05 N during the return process (Lb) are measured. This measurement is performed on three sample pieces, and the average value of the gripping distance length (Lf) (Lf1) and the average value of the gripping distance length (Lb) (Lb1) are obtained by taking the arithmetic mean of the lengths. The value calculated from the following formula is defined as the "recovery rate at 50% elongation" in the MD direction. Recovery rate (%) at 50% elongation = [[(L50-Lf1)―(Lb1-Lf1)] / (L50-Lf1)] × 100

[0073] Furthermore, by subjecting a sample taken so that the direction perpendicular to the production direction of the object to be measured (CD direction) and the long side direction are parallel to each other to the above measurement, the "recovery rate at 50% elongation" in the CD direction can be determined.

[0074] An example of a method for manufacturing the stretchable fiber sheet (100) of the present invention will be described below. The method for preparing the stretchable fiber sheet (100) of the present invention can be appropriately selected, but for example, it can be prepared through the following steps. (1) A process of preparing a fiber web containing latent crimped fibers. (2) A step of forming multiple portions on one main surface of the fiber web by applying ultrasonic sealing to the fiber web, thereby creating a fused structure in which the constituent fibers of the fiber web (including the latent crimped fibers) are melted together. (3) A step of subjecting the ultrasonically sealed fiber web to heat treatment to bring out the crimp of the latent crimp fibers.

[0075] Next, I will explain each step in detail.

[0076] First, in step (1), the method for preparing the fiber web containing latent crimp fibers can be appropriately selected. Specifically, it can be a crosslay web, parallel lay web, crisscross web, or random web obtained by a dry method, a wet method, or a direct spinning method. Furthermore, in order to prepare an elastic fiber sheet (100) with excellent elasticity, it is preferable that the constituent fibers of the fiber web consist only of latent crimp fibers.

[0077] Next, in step (2), the form of the melted and integrated portions of each constituent fiber, including the latent crimped fibers formed by ultrasonic sealing, can be adjusted as appropriate. However, in order to prepare an elastic fiber sheet (100) with excellent elasticity, it is preferable that the melted and integrated portions have the same shape and are distributed at equal intervals from one another.

[0078] Furthermore, the spacing between adjacent fused portions formed in the fiber web shall be less than or equal to the apparent fiber length of the latent crimped fiber. The apparent fiber length of the latent crimped fiber referred to here is the value measured by the measurement method described above (Method for measuring the apparent fiber length of crimped fiber), in which the terms "stretchable fiber sheet" or "fiber layer" are replaced with "fiber web" as the measurement target, and the term "crimped fiber" is replaced with "latent crimped fiber" as the measurement target. The apparent fiber length of the latent crimped fiber is less than or equal to the fiber length of the latent crimped fiber. With this configuration, both ends of the latent crimped fiber can be fixed by adjacent fused portions.

[0079] Furthermore, it is more preferable that the spacing between adjacent fused portions formed in the fiber web is less than half the apparent fiber length of the latent crimped fibers. This configuration allows more latent crimped fibers to be fixed between their ends in adjacent fused portions, increasing the proportion of crimped fibers fixed by the fiber fixing portion (12). The spacing between adjacent fused portions formed in the fiber web can be adjusted as appropriate, but it is preferably less than half the apparent fiber length of the latent crimped fibers, preferably less than 40%, preferably less than 30%, and preferably less than 20%. By subjecting a fiber web in which the spacing between adjacent fused portions is less than half the apparent fiber length of the latent crimped fibers to the next step of inducing crimp in the latent crimped fibers by a heat treatment described later, an even more rigid stretchable fiber sheet (100) can be produced.

[0080] By subjecting the fiber web prepared in this manner to the next step of heat treatment to induce crimping of latent crimped fibers, an elastic fiber sheet (100) can be manufactured, which has a fiber layer (11) in which the shortest distance between adjacent fiber fixing portions (12) is less than or equal to the apparent fiber length of the crimped fibers.

[0081] Finally, in step (3), the ultrasonically sealed fiber web is subjected to heat treatment to induce crimping of the latent crimp fibers. The heat treatment method can be selected as appropriate, but for example, it can be heated or heated and pressurized using a roller, heated using a heating device such as an oven dryer, far-infrared heater, dry heat dryer, or hot air dryer, or heated by irradiating with infrared rays under no pressure to heat the contained organic resin.

[0082] In addition, the temperature for heating the fiber web, when using latent crimp fibers, is the temperature at which the crimp of the latent crimp fibers is manifested, and it is preferably adjusted to a temperature at which unintended denaturation does not occur in the components of the fiber web (constituent fibers, binder, functional components, etc.). In this step, the constituent fibers of the fiber web may be adhesively integrated by melting the binder and / or exerting the fiber adhesion function by the adhesive fibers.

[0083] Through the above steps, the stretchable fiber sheet (100) according to the present invention can be manufactured.

[0084] The stretchable fiber sheet (100) of the present invention may further include members such as another porous body, film, foam, etc. Further, the stretchable fiber sheet (100) of the present invention may be subjected to a step of pressure treatment such as a resilient press treatment to smooth the surface. Also, it may be subjected to various secondary processing steps such as a step of heat molding after punching into a shape according to the application and usage mode, a step of carrying a functional component, a hydrophilization treatment step for improving the affinity with a drug, etc.

Examples

[0085] Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.

[0086] (Method for preparing fiber layer)<00,00367>Only the latent crimp fibers of a polyester resin configured in a side-by-side type (fiber cross-sectional shape: circular, fineness: 2.2 dtex, fiber length: 51 mm, does not melt under heating conditions of 160 °C, and crimp manifestation occurs at 120 °C or higher) were fed into a carding machine, and a parallel web with a basis weight of 20 g / m 2 and a parallel web with a basis weight of 40 g / m 2 were prepared. Also, the prepared parallel web with a basis weight of 20 g / m 2 was overlaid, and a cross-laid web with a basis weight of 40 g / m 2 was prepared.

[0087] (Comparative Example 1) Weight: 40g / m 2 A heat seal was applied to one main surface of the parallel web in the manner shown in Figure 3, forming multiple fiber-fixed portions where the latent crimped fibers were fused together. The shortest distance between adjacent fiber-fixed portions was less than or equal to the apparent fiber length of the latent crimped fibers. Finally, the heat-sealed parallel web was subjected to a hot air dryer (heating temperature: 160°C) to induce crimping of the latent crimp fibers contained in the fiber web, thereby preparing an elastic fiber sheet. In the stretchable fiber sheet prepared in this manner, when a straight line was drawn on the main surface of the fiber layer, there were straight lines among the drawn lines that did not intersect with any of the fiber fixing portions. Furthermore, the shortest distance between adjacent fiber-fixed portions (derived from the heat-sealed portions) was 15 mm, which was shorter than the apparent fiber length (16 mm) of the crimped fibers formed when the latent crimped fibers exhibited crimp. Furthermore, each fiber-fixing portion that was formed (each fiber-fixing portion whose entire shape could be observed without interruption) was identical in shape, equally spaced from one another, and distributed on the main surface.

[0088] (Comparative Example 2) An ultrasonic seal was applied to one main surface of the crosslay web in the manner shown in Figure 4, forming multiple fiber-fixed portions where latent crimped fibers were fused together. The shortest distance between adjacent fiber-fixed portions was less than or equal to the apparent fiber length of the latent crimped fibers. Finally, the ultrasonically sealed parallel web was subjected to a hot air dryer (heating temperature: 160°C) to induce crimping of the latent crimp fibers contained in the fiber web, thereby preparing an elastic fiber sheet. In the stretchable fiber sheet prepared in this manner, when a straight line was drawn on the main surface of the fiber layer, there were straight lines among the drawn lines that did not intersect with any of the fiber fixing portions. Furthermore, the shortest distance between adjacent fiber-fixed portions (derived from the ultrasonically sealed portions) was 10 mm, which was shorter than the apparent fiber length (16 mm) of the crimped fibers formed when the latent crimped fibers exhibited crimping. Furthermore, each fiber-fixing portion that was formed (each fiber-fixing portion whose entire shape could be observed without interruption) was identical in shape, equally spaced from one another, and distributed on the main surface.

[0089] (Comparative Example 3) An ultrasonic seal was applied to one main surface of the crosslay web in the manner shown in Figure 5, forming multiple fiber-fixed portions where latent crimped fibers were fused together. The shortest distance between adjacent fiber-fixed portions was less than or equal to the apparent fiber length of the latent crimped fibers. Finally, the ultrasonically sealed parallel web was subjected to a hot air dryer (heating temperature: 160°C) to induce crimping of the latent crimp fibers contained in the fiber web, thereby preparing an elastic fiber sheet. In the stretchable fiber sheet prepared in this manner, when a straight line was drawn on the main surface of the fiber layer, there were straight lines among the drawn lines that did not intersect with any of the fiber fixing portions. Furthermore, the shortest distance between adjacent fiber-fixed portions (derived from the ultrasonically sealed portions) was 10 mm, which was shorter than the apparent fiber length (16 mm) of the crimped fibers formed by the latent crimped fibers exhibiting crimp. Furthermore, each fiber-fixing portion that was formed (each fiber-fixing portion whose entire shape could be observed without interruption) was identical in shape, equally spaced from one another, and distributed on the main surface.

[0090] (Example 1) An ultrasonic seal was applied to one main surface of the crosslay web in the manner shown in Figure 6, forming multiple fiber-fixed portions where latent crimped fibers were fused together. The shortest distance between adjacent fiber-fixed portions was less than or equal to the apparent fiber length of the latent crimped fibers. Finally, the ultrasonically sealed parallel web was subjected to a hot air dryer (heating temperature: 160°C) to induce crimping of the latent crimp fibers contained in the fiber web, thereby preparing an elastic fiber sheet. In the stretchable fiber sheet prepared in this manner, when straight lines were drawn on the main surface of the fiber layer, all of the drawn straight lines intersected with multiple fiber fixing portions. Furthermore, the shortest distance between adjacent fiber-fixed portions (derived from the ultrasonically sealed portions) was 10 mm, which was shorter than the apparent fiber length (16 mm) of the crimped fibers formed by the latent crimped fibers exhibiting crimp. Furthermore, each fiber-fixing portion that was formed (each fiber-fixing portion whose entire shape could be observed without interruption) was identical in shape, equally spaced from one another, and distributed on the main surface.

[0091] Table 1 summarizes the various physical properties of the comparative and example stretchable fiber sheets prepared as described above. Items that were not measured are indicated with "-" in the table.

[0092] [Table 1]

[0093] The stretchable fiber sheets prepared in Comparative Examples 1-3 and Example 1 all possessed sufficient stretchability. However, the stretchable fiber sheets of Comparative Examples 1-3, which did not satisfy the configuration of the present invention, had lower tensile strength in the MD and CD directions than Example 1, as well as lower tensile strength at 20% and 50% stretch in the MD direction, and were inferior in rigidity.

[0094] On the other hand, the stretchable fiber sheet satisfying the configuration of the present invention had sufficient stretchability, high tensile strength in the MD and CD directions, high strength at 20% and 50% stretch in the MD direction, and excellent rigidity. [Industrial applicability]

[0095] The elastic fiber sheet of the present invention can be suitably used as a medical product or hygiene product such as the waistband or groin area of ​​diapers, supporters and bandages, adhesive medicinal bases and plaster bases, and facial masks. [Explanation of Symbols]

[0096] A: One direction B: A direction perpendicular to one direction 10, 100: Stretchable fiber sheet 11: Fiber layer 2, 12: Fiber fixing part

Claims

[Claim 1] An elastic fiber sheet comprising a fiber layer containing crimped fibers, The constituent fibers of the aforementioned fiber layer are short fibers cut to a specific length. The aforementioned fiber layer has multiple fiber fixing portions of the same shape on its main surface. Each of the aforementioned fiber fixing portions, having the same shape, is distributed and located on the main surface of the fiber layer, on an oblique grid or at the intersections of the grid. When a straight line is drawn on the main surface passing through it, the straight line has multiple points of intersection with the fiber fixing portions. The shortest distance between adjacent fiber fixing portions on the main surface is 10 mm or more. The shortest distance between adjacent fiber fixing portions on the main surface is less than or equal to the apparent fiber length of the crimped fiber. Stretchable fiber sheet.

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