Nonwoven fabric and method for manufacturing the same

Abstract

To provide a stretchable and bulky nonwoven fabric available for medical and sanitary articles, and a manufacturing method thereof.SOLUTION: A stretchable and bulky nonwoven fabric can be provided by applying an embossing roll to a web containing latent crimp fibers to form a plurality of high-density joined portions on the web, heating the latent crimp fibers exposed on one principal surface to cause crimps to be expressed, and subsequently causing crimps to be expressed on whole latent crimp fibers contained in the web. The nonwoven fabric with uneven surface produced in such a way has a structure in which "the number of crimps is larger in the crimp fibers on the one principal surface than the crimp fibers on a portion surrounded by both principal surfaces and the adjacent concave portions at a convex portion".SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a stretchable, bulky nonwoven fabric that can be used for medical supplies, hygiene products, and the like, and to a method for manufacturing the same. [Background technology]

[0002] In recent years, nonwoven fabrics, which are highly flexible and stretchable, have been adopted as components for medical and hygiene products such as diaper waistbands and groin areas, supporters and bandages, adhesive medicinal bases and plaster bases, and facial masks. Furthermore, because they are highly cushioned and have a pleasant feel against the skin, bulkiness is also required for these nonwoven fabrics.

[0003] As a specific example of a bulky, stretchable nonwoven fabric that can satisfy such requirements, for example, Japanese Patent Application Publication No. 2003-52749 (Patent Document 1) discloses a fiber aggregate (nonwoven fabric) as shown in Figure 1, which is composed of latent crimpable fibers that exhibit crimping, and in which numerous embossed portions (2) are scattered in a discontinuous pattern. It is also disclosed that by using this nonwoven fabric, a bulky, stretchable absorbent sheet (1) can be provided. Furthermore, Patent Document 1 discloses a method for manufacturing the nonwoven fabric, in which a web made of latent crimpable fibers is embossed, and then the web is heated to a predetermined temperature to induce the crimping action of the latent crimpable fibers present between the embossed portions (2) in order to form stretchable regions (3) that have bulkiness and elasticity between the embossed portions (2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-52749 [Overview of the project] [Problems that the invention aims to solve]

[0005] After further consideration, the applicant concluded that it would be difficult to provide an even bulkier nonwoven fabric with elasticity using the nonwoven fabric and manufacturing method disclosed in Patent Document 1. In other words, in the nonwoven fabric and manufacturing method disclosed in Patent Document 1, the bulkiness of the nonwoven fabric is mainly due to the crimped fibers (latent crimped fibers that have undergone crimping in Patent Document 1) present in the stretchable region (3). That is, the crimping of latent crimped fibers causes them to become stretchable crimped fibers, forming the stretchable region (3) and making the nonwoven fabric bulky. Therefore, since there is a direct proportional relationship between the elasticity of the crimped fibers (the crimped state of the crimped fibers) and the bulkiness of the nonwoven fabric, the applicant concluded that it would be difficult to achieve a nonwoven fabric that is even bulkier than the elasticity of the crimped fibers (the crimped state of the crimped fibers).

[0006] One of the objectives of the present invention is to provide a nonwoven fabric that is both stretchable and bulky. [Means for solving the problem]

[0007] The first invention of this application is, "Constituent fibers" It consists of only one type of crimped fiber, A nonwoven fabric having two exposed main surfaces, One main surface has a plurality of recessed portions and convex portions located between adjacent recessed portions. In the recessed portion, the constituent fibers are bonded together. The crimped fibers on the surface of one of the main surfaces have a greater number of crimps than the crimped fibers on the surface of the convex portion that are surrounded by the two main surfaces and the adjacent concave portions. Nonwoven cloth. " Therefore, the second present invention is, (1) The constituent fibers consist of only one type of latent crimp fiber. The process of preparing a website, (2) A step of forming a plurality of high-density bonded portions on the web by applying an embossing roll from one main surface of the web, and heating the latent crimped fibers exposed on the one main surface to cause crimping, (3) A step of subjecting the web that has gone through step (2) to heat treatment in order to cause crimp to appear in the latent crimp fibers contained in the web, A method for producing a nonwoven fabric according to claim 1, comprising the following: That is the case. [Effects of the Invention]

[0008] As a result of further consideration, the applicant has come to provide an even bulkier nonwoven fabric, which has the following configuration: "The crimped fibers on the surface on one of the main surfaces have a greater number of crimps than the crimped fibers on the surface on one of the main surfaces in the convex portion, in the portion surrounded by the two main surfaces and the adjacent concave portion."

[0009] Furthermore, as a result of continued investigation by the applicant, it was found that the method for manufacturing nonwoven fabric according to the present invention can provide a nonwoven fabric having the above-described structure and even greater bulkiness.

[0010] As disclosed in Patent Document 1, in the prior art method for manufacturing a nonwoven fabric with an uneven surface and elasticity, multiple high-density bonding portions are formed by applying an embossing roll from one main surface of a web containing latent crimp fibers. Subsequently, the web is subjected to a heat treatment to induce crimping throughout the latent crimp fibers present in the web.

[0011] In contrast to the manufacturing method described above, the method for manufacturing nonwoven fabric according to the present invention is characterized by forming multiple high-density bonding portions by applying an embossing roll from one main surface of a web containing latent crimp fibers, and by heating the latent crimp fibers that are selectively exposed on one main surface to induce crimping.

[0012] In this process, the applicant has formed multiple high-density bonding regions on the web, and has selectively caused crimping in the latent crimp fibers exposed on one main surface of the web, without causing crimping in all the latent crimp fibers present in the web. In other words, in a web that has undergone this process, the latent crimp fibers on the surface of the web are more sufficiently crimped than the latent crimp fibers present inside the web. Therefore, the surface of the web is difficult to deform, possibly because the constituent fibers are strongly intertwined, and does not easily follow the deformation of other parts (such as the inside of the web or the other main surface of the web). In this process, when forming multiple high-density bonding regions on the web, the web is fixed by the action of an embossing roll and is in a state that is difficult to deform, such as shrinking. For example, it is fixed between the pins and receiving roll of the embossing roll and is in a state that is difficult to deform, such as shrinking. Then, under these conditions, it is heated by the embossing roll, which selectively causes crimping in the latent crimp fibers exposed on one main surface. Therefore, the crimping of the latent crimped fibers occurs while preventing shrinkage from occurring throughout the entire web.

[0013] Then, the web is subjected to a heat treatment to induce crimping in all of the latent crimped fibers present in the web. In this step (step (3)), when crimping is induced in all of the latent crimped fibers contained in the web by subjecting it to a heat treatment, the crimped fibers inside the web shrink, shortening the length between adjacent high-density bonded portions, while the surface of the web is less able to follow this shrinkage and protrudes significantly. In other words, in the method for manufacturing nonwoven fabric according to the present invention, the difference in the ease of deformation between the surface and the interior of the web in this step (step (3)) results in the production of an even bulkier nonwoven fabric.

[0014] Furthermore, in nonwoven fabrics manufactured by the manufacturing method of the present invention, the crimped fibers present on the surface of the convex portion (the surface on one of the main surfaces) are subjected to heat in at least two stages to induce crimping. Therefore, the number of crimped fibers is greater than that of the latent crimped fibers present inside the convex portion (the portion of the convex portion surrounded by both main surfaces and the adjacent concave portions).

[0015] From the above, the present invention can provide a bulkier nonwoven fabric having stretchability.

Brief Description of the Drawings

[0016] [Figure 1] It is a schematic cross-sectional view showing a cross-section of a sheet for absorbent articles according to Patent Document 1. [Figure 2] It is a schematic front view of the nonwoven fabric according to the present invention as seen from one main surface side. [Figure 3] It is a schematic cross-sectional view showing a cross-section of the nonwoven fabric according to the present invention. [Figure 4] It is a schematic cross-sectional view showing the manufacturing process of the nonwoven fabric according to the present invention. [Figure 5] It is a photograph of the nonwoven fabric prepared in Example 1 taken from an obliquely upward direction on one main surface side. [Figure 6] It is a photograph of the nonwoven fabric prepared in Example 1 taken from an obliquely upward direction on the other main surface side. [Figure 7] It is a photograph of the nonwoven fabric prepared in Comparative Example 1 taken from an obliquely upward direction on one main surface side. [Figure 8] It is a photograph of the nonwoven fabric prepared in Comparative Example 1 taken from an obliquely upward direction on the other main surface side.

Modes for Carrying Out the Invention

[0017] In the present invention, various configurations can be appropriately selected, such as the following configuration. Unless otherwise specified, the various measurements described in the present invention were performed under atmospheric pressure. Furthermore, the measurements were performed under a temperature of 25°C. Unless otherwise specified, the various measurement results described in the present 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. For 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. Furthermore, the upper and lower limits exemplified in the present invention can be combined arbitrarily.

[0018] The nonwoven fabric according to the present invention will be explained primarily with reference to Figures 2 to 4. A schematic cross-sectional view of the nonwoven fabric obtained by cutting the nonwoven fabric shown in Figure 2 between line segments AA is shown in Figure 3.

[0019] The nonwoven fabric (100, hereafter sometimes referred to as the nonwoven fabric) according to the present invention, having two main surfaces containing crimped fibers as constituent fibers, has a plurality of recessed portions (101) and convex portions (102) located between adjacent recessed portions (101) on one main surface side (M side). The recessed portions (101) include portions (103, hereafter sometimes referred to as high-density bonded portions) where the constituent fibers are bonded together by melting and integrating through embossing, or by bonding and integrating through a binder or fiber adhesive, thereby reducing the thickness of the nonwoven fabric (100) and increasing its density. In Figures 2 to 4, the high-density bonded portions (103) are represented as areas painted gray. Since the high-density bonded portions (103) are thinner than the nonwoven fabric (100), the recessed portions (101) are formed around the high-density bonded portions (103). Furthermore, when viewing the nonwoven fabric (100) from one main surface side (M side), the straight line connecting the high-density bonding portions (103) at the shortest distance (shown as a dashed line in Figure 1) may also be a portion that is thinner than the nonwoven fabric (100).

[0020] The aforementioned protruding portion (102) is located within the area enclosed by the adjacent recessed portions (101) as described above, or within the area enclosed by the adjacent recessed portions (101) and the dashed line described above.

[0021] In addition, it is preferable that the nonwoven fabric (100) according to the present invention does not have recessed portions (101) and convex portions (102) on the other main surface side (M' side). This configuration is preferable because it allows for the formation of more prominent convex portions (102), providing a more bulky nonwoven fabric (100) with elasticity.

[0022] The nonwoven fabric (100) according to the present invention is characterized in that the crimped fibers present on the surface (105) of one of the main surfaces (M side) have a greater number of crimps than the portion (104) of the convex portion (102) surrounded by both main surfaces (the main surface on the M side and the main surface on the M' side) and the adjacent concave portion (101). Whether the crimped fibers present inside the convex portion (104) or on the surface (105) of the convex portion have a greater number of crimps can be determined by comparing them using the following verification method.

[0023] (How to check the number of folds) (1) Prepare a nonwoven fabric having multiple recesses and protruding portions between adjacent recesses. (2) Take an optical microscope image or electron microscope image (hereinafter collectively referred to as a microscope image) of the central part of the surface of one convex portion when viewing the nonwoven fabric from one main surface side (M side) (shooting range: a square area of ​​3 mm × 3 mm). If necessary, multiple microscope images may be taken and the multiple microscope images taken may be stitched together to prepare a microscope image. (3) From the crimped fibers present in the aforementioned range visible in the microscope image, 30 fibers are randomly selected. The number of crimps in each fiber (the number of crimps present in a 2 mm fiber length in each fiber) is then visually counted, and the average value of the number of crimps is calculated. (4) For the other five convex parts, calculate the average number of crimps in the same manner as in (2) and (3) above, and then find the average A of these values. (5) The surface (105) of the convex portion from which the microscope photograph was taken is removed to expose the interior (104) of the convex portion. The same process is performed on the other five convex portions from which the microscope photograph was taken. (6) Take a micrograph of the central part of the surface of the portion where the interior (104) of the convex part is exposed when viewing the nonwoven fabric from one main side (M side) (shooting range: a square area of ​​3 mm x 3 mm). If necessary, multiple micrographs may be taken and the multiple micrographs taken may be stitched together to prepare a micrograph. (7) From the fibers having crimp in the area where the interior (104) of the convex portion is exposed as seen in the microscope photograph, 30 fibers are randomly selected. The number of crimps in each fiber (the number of crimps present in a 2 mm fiber length in each fiber) is then visually counted, and the average value of the number of crimps is calculated. (8) For the other five protruding parts where the interior (104) is exposed, the average number of crimps is calculated for each in the same manner as in (6) and (7) above, and then the average of these values ​​B is calculated. (9) If the average value A > average value B, the measured nonwoven fabric is judged to have "more crimps on the surface of one of the main surfaces than on the crimps on the surface of the convex portion surrounded by both main surfaces and the adjacent concave portion." In all other cases (if average value A ≤ average value B), the measured nonwoven fabric is judged not to satisfy the above-mentioned configuration.

[0024] In the nonwoven fabric (100) according to the present invention, it is preferable that the constituent fibers are more bonded to each other on the surface (105) of the convex portion than on the interior (104) of the convex portion. This configuration allows for an even bulkier nonwoven fabric (100). Here, "bonded to each other" means that the fibers constituting the convex portion (102) (especially crimped fibers) are melted and integrated together, or bonded together by a binder or fiber adhesive. Whether the interior (104) or the surface (105) of the convex portion has more bonded constituent fibers can be determined by comparing them using the following verification method.

[0025] (Method for checking the bonding state between constituent fibers) (1) Prepare a nonwoven fabric having multiple recesses and protruding portions between adjacent recesses. (2) Take an optical microscope image or electron microscope image (hereinafter collectively referred to as a microscope image) of the central part of the surface of one convex portion when viewing the nonwoven fabric from one main surface side (M side) (shooting range: a square area of ​​3 mm × 3 mm). If necessary, multiple microscope images may be taken and the multiple microscope images taken may be stitched together to prepare a microscope image. (3) Count the number of bonding points between constituent fibers present in the area visible in the microscope image. A bonding point refers to a portion where at least a part of two or more constituent fibers are joined together by adhesive or fusion. (4) For the other five protruding parts, calculate the number of connection points in the same manner as in (2) and (3) above, and then find the average value A of these values. (5) The surface (105) of the convex portion from which the microscope photograph was taken is removed to expose the interior (104) of the convex portion. The same process is performed on the other five convex portions from which the microscope photograph was taken. (6) Take a micrograph of the central part of the surface of the portion where the interior (104) of the convex part is exposed when viewing the nonwoven fabric from one main side (M side) (shooting range: a square area of ​​3 mm x 3 mm). If necessary, multiple micrographs may be taken and the multiple micrographs taken may be stitched together to prepare a micrograph. (7) Count the number of bonding points between constituent fibers in the area where the interior (104) of the convex portion is exposed in the microscope photograph. (8) For the other five protruding parts where the interior (104) is exposed, the number of joints is calculated for each in the same manner as in (6) and (7) above, and the average value B of these values ​​is then calculated. (9) If the average value A > average value B, the measured nonwoven fabric is judged to have "more constituent fibers bonded together on the surface on one of the main surfaces than in the area surrounded by both main surfaces and the adjacent recessed portion in the convex portion." Otherwise (if the average value A ≤ average value B), the measured nonwoven fabric is judged to not satisfy the above-mentioned composition.

[0026] Furthermore, in order to efficiently provide an even bulkier nonwoven fabric (100) with elasticity, it is preferable that the crimped fibers present inside (104) of the convex portion and the crimped fibers present on the surface (105) of the convex portion are of the same type (for example, crimped fibers in which the crimping of the same type of latent crimped fiber has manifested).

[0027] The nonwoven fabric (100) contains crimped fibers as constituent fibers. The crimped fibers referred to here are, for example, fibers with crimp or composite fibers formed by the crimping of latent crimped fibers (for example, core-sheath type, sea-island type, side-by-side type, orange type, etc.). Because the nonwoven fabric (100) contains crimped fibers, convex portions (102) are formed, making it bulky and highly elastic.

[0028] The nonwoven fabric (100) may contain other fibers besides crimped fibers, 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, as will be described later, and their fiber length and fineness can be the same as those of the crimped fibers.

[0029] The mass ratio of crimped fibers to the total mass of fibers constituting the nonwoven fabric (100) is adjusted as appropriate, but 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, and is more preferably composed of crimped fibers only, in order to provide a nonwoven fabric (100) that is bulky and highly elastic by forming more protruding convex portions (102).

[0030] The polymers that make up the constituent fibers (hereinafter sometimes referred to as constituent fibers) of the nonwoven fabric (100) containing crimped fibers can be appropriately selected, for example, polyolefin resins (e.g., polyethylene, polypropylene, polymethylpentene, polyolefin resins with a structure in which part of the hydrocarbon is replaced with a nitrile group or halogen such as fluorine or chlorine), styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (e.g., polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, polybutylene naphthalate, polycarbonate, polyarylate, polybutylene naphthalate, polycarbonate, polyarylates, polybutylene naphthalate, polyethylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, polybutylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylates, polybutylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylates, polybutylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylates, polybutylene naphthalate, polybutylene naphthalate, polystyrene naphthalate, polybutylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylates, polybutylene naphthalate, polybutylene naphthalate, polybutylene naphthalate, polystyrene Known polymers can be used, such as aromatic 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.), fluorine resins (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.). 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 properties of the polymers may be anything. In addition, a mixture of multiple resins is also acceptable.

[0031] The constituent fibers may be composed of one type of resin or multiple types of resins. Fibers composed of multiple types of resins can be generally referred to as composite fibers, and may take the form of, for example, core-sheath type, sea-island type, side-by-side type, orange type, bimetal type, etc.

[0032] Furthermore, the constituent fibers may contain additives other than the resins mentioned above, such as flame retardants, fragrances, pigments, dyes, antibacterial agents, antifungal agents, photocatalytic particles, emulsifiers, dispersants, surfactants, and thickeners. The inclusion of pigments allows for the creation of dope-dyed fibers, such as fibers in colors resembling skin tones (e.g., light orange). Dyes may also be used to color the fibers.

[0033] Furthermore, the constituent fibers may include fibers with irregular cross-sections in addition to approximately circular or elliptical fibers. These irregular cross-section fibers may have cross-sections such as hollow shapes, polygonal shapes like triangles, alphabetic shapes like Y-shapes, irregular shapes, multi-lobed shapes, symbolic shapes like asterisks, or shapes formed by combining multiple such shapes.

[0034] The fineness of the constituent fibers can be appropriately selected, and to provide a bulky nonwoven fabric with excellent flexibility, conformability, elasticity, and stretch recovery, it can be, for example, 0.01 to 100 dtex, 0.1 to 50 dtex, 0.5 to 30 dtex, or 1 to 10 dtex.

[0035] Furthermore, the fiber length of the constituent fibers 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 so that a bulky and highly elastic nonwoven fabric (100) can be provided by forming more protruding convex portions (102). The fiber length can be 20-150 mm, 25-100 mm, 30-90 mm, or 40-80 mm, especially when creating the web using the dry method. Also, when creating the web using the wet method, the fiber length can be 1-30 mm, 3-20 mm, or 5-15 mm. Note that "fiber length" refers to the fiber length measured in accordance with JIS L1015 (2010), 8.4.1c Direct method (Method C).

[0036] The constituent fibers can be obtained by known methods such as melt spinning, dry spinning, wet spinning, direct spinning (meltblown, spunbond, electrostatic spinning, etc.), methods for extracting fine fibers by removing one or more resin components from composite fibers, and methods for obtaining divided fibers by beating the fibers.

[0037] The nonwoven fabric (100) can be a nonwoven fabric prepared using a unidirectional web, a crosslay web, a random web, or a crisscross web formed by laminating these webs. Furthermore, it can be a nonwoven fabric prepared using a web to which a water flow or needles have been applied (water-entangled web or needle-punched web). Using a web to which a water flow or needles have been applied is preferable because it provides a nonwoven fabric (100) with high strength due to the strong entanglement of the constituent fibers.

[0038] In particular, it is preferable that the nonwoven fabric (100) is prepared using a crosslay web, a crisscross web formed by laminating a crosslay web and a unidirectional web or a crosslay web and a random web, or a random web, so as to provide a bulky and highly elastic nonwoven fabric (100) with more prominent convex portions (102) formed by having multiple fiber orientations or not having a specific fiber orientation.

[0039] The composition and physical properties of these webs, such as basis weight and thickness, can be adjusted as needed, but the basis weight is 5-1000 g / m². 2 It can be 10-800g / m² 2 It can be 20-500g / m² 2 It can be 30-300g / m 2 It can be 40-100g / m 2 It can be such. The thickness can be 0.05 to 30 mm, 0.1 to 20 mm, or 0.5 to 10 mm. In this invention, "basis value" refers to the area of ​​the main surface 1 m². 2This refers to the mass per unit area. Furthermore, thickness is defined as 20 gf / cm². 2 This refers to the thickness of the part to which the load is applied when a load is applied.

[0040] The nonwoven fabric (100) may contain functional components. The type of functional component is not limited, as it can be appropriately selected depending on the desired 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, medicinal components, and cosmetic components. The functional components may exist as particulate matter on and / or inside the constituent fibers, or as a film covering part or all of the surface of the constituent fibers. The method for supporting the functional components on the constituent fibers can be appropriately selected, but for example, one method can be employed in which a solution or dispersion of the functional components, or a solution or dispersion of the functional components containing a binder, is supported on one or both main surfaces of the nonwoven fabric (100) by spraying or known coating methods (e.g., a kiss coating method using a gravure roll, a die coating method, etc.), and then the solvent and dispersion medium are removed; or one method can be employed in which the nonwoven fabric (100) is immersed in the above-mentioned solution or dispersion, and then the solvent and dispersion medium are removed.

[0041] The number of recessed portions (101) and high-density bonding portions (103) provided in the nonwoven fabric (100) may be two or more, but it is preferable that it be three or more or four or more.

[0042] The distribution of the recessed portions (101) and high-density bonding portions (103) can be adjusted as appropriate. Specifically, the recessed portions (101) and high-density bonding portions (103) can exist in linear or grid-like patterns, randomly distributed, in a patterned manner, or in a pattern of equally spaced dots. Of these, it is preferable that the spacing between the recessed portions (101) and the high-density bonding portions (103) is equal, so as to provide a nonwoven fabric (100) that is bulky and highly elastic by forming more protruding convex portions (102). As an example of such a configuration, as shown in Figure 1, it is preferable that the recessed portions (101) and high-density bonding portions (103) are located on the intersections of a grid that is assumed to be equally spaced (a configuration of equally spaced dots).

[0043] When viewing the nonwoven fabric (100) from one main surface side (M side), the distance between the centers of adjacent recesses (101) and the distance between the centers of adjacent high-density bonding portions (103) are adjusted as appropriate to provide a bulky and highly elastic nonwoven fabric (100) by forming more protruding convex portions (102). Specifically, these distances can be 0.1 to 200 mm, 0.5 to 100 mm, 1 to 75 mm, and 5 to 50 mm.

[0044] When viewing the nonwoven fabric (100) from one main surface side (M side), the size of the high-density bonding portion (103) is adjusted as appropriate so that a bulky and highly elastic nonwoven fabric (100) is provided by forming a more protruding convex portion (102). Specifically, the diameter can be 0.1 to 15 mm, 1 to 10 mm, or 2 to 5 mm.

[0045] The thickness of the high-density bonding portion (103) is adjusted as appropriate according to the application and required physical properties of the nonwoven fabric (100), but its thickness is smaller than the thickness of the nonwoven fabric (100) (the height of the convex portion (102), as described later). The comparison between the thickness of the high-density bonding portion (103) and the thickness of the nonwoven fabric (100) (the height of the convex portion (102), as described later) can be confirmed by observing the cross-section of the nonwoven fabric (100) obtained by cutting it between line segments AA passing through the centers of the convex portions (102), as shown in Figure 2.

[0046] The number of protrusions (102) on the nonwoven fabric (100) may be one or more, but it is preferable that the number of protrusions (102) be two or more in order to provide a nonwoven fabric (100) that is bulky and highly elastic. The distribution of the protrusions (102) can be adjusted as appropriate. Specifically, it can be the same as the distribution of the recessed parts (101). Of these, it is preferable that the protrusions (102) are distributed at equal intervals in order to provide a nonwoven fabric (100) that is bulky and highly elastic. As an example of this configuration, as shown in Figure 1, it is preferable that the protrusions (102) are located on the intersections of a grid that is assumed to be at equal intervals.

[0047] If the nonwoven fabric (100) has multiple protrusions (102), the distance between the centers of adjacent protrusions (102) is adjusted as appropriate to provide a nonwoven fabric (100) that is bulky and highly elastic. Specifically, it can be 0.1 to 100 mm, 0.5 to 180 mm, 1 to 75 mm, or 5 to 50 mm.

[0048] The thickness of the convex portion (102) is adjusted as appropriate according to the application and required physical properties of the nonwoven fabric (100), but the lower limit of its thickness can be 0.1 mm or more, 0.3 mm or more, or 0.5 mm or more, and the upper limit can be 100 mm or less, 80 mm or less, 50 mm or less, 20 mm or less, or 10 mm or less. Note that the thickness of the convex portion (102) can be the same as the thickness of the non-woven fabric (100) described later.

[0049] Various configurations and physical properties such as the basis weight and thickness of the non-woven fabric (100) can be adjusted as appropriate. The basis weight can be 5 to 1000 g / m 2 and can be 10 to 500 g / m 2 and can be 20 to 400 g / m 2 The lower limit of the thickness can be 0.1 mm or more, can be 0.3 mm or more, can be 0.5 mm or more, and the upper limit can be 100 mm or less, can be 80 mm or less, can be 50 mm or less, can be 20 mm or less, and can be 10 mm or less.

[0050] Regarding the other main surface (the main surface on the M' side) of the non-woven fabric (100), its form can be adjusted as appropriate. However, in order to provide a non-woven fabric (100) that is thick and rich in stretchability, it preferably has a flat shape without concave portions (101) and convex portions (102). Also, in order to provide a non-woven fabric (100) that is thick and rich in stretchability, the crimped fibers present on the surface (105) of the convex portion (102) on one main surface (the M side) preferably have a larger number of crimps than the other main surface (the M' side).

[0051] Note that the number of crimps of the crimped fibers present on the other main surface (the M' side) can be confirmed as follows. (1) In the above-described (method for confirming the number of crimps), take a microscopic photograph of the central portion of the surface portion on the other main surface side (the M' side) facing the convex portion (102) selected to obtain the average value A (photographing range: a square range of 3 mm × 3 mm). Note that, if necessary, a plurality of microscopic photographs can be taken and the photographed plurality of microscopic photographs can be joined together to prepare a microscopic photograph. (2) From the crimped fibers present in the area visible in the microscope image, 30 fibers are randomly selected. The number of crimps in each fiber (the number of crimps present in a 2 mm fiber length in each fiber) is then visually counted, and the average number of crimps is calculated. (3) In order to find the average value A of the other five locations, the average value of the number of crimps is calculated for each of the selected convex parts (102) in the same manner as in (1) and (2) above, and then the average value C of these values ​​is calculated. If the average value A > average value C, the measured nonwoven fabric is judged to have "more crimped fibers on the surface (105) of the convex portion (102) on one main surface (M side) than on the other main surface (M' side main surface)." In all other cases (if average value A ≤ average value C), the measured nonwoven fabric is judged not to satisfy the above-mentioned configuration.

[0052] The method for preparing the nonwoven fabric (100) of the present invention can be appropriately selected, but for example, a manufacturing method comprising the following steps (1) to (3) can be exemplified. These steps will be explained with reference to Figure 4.

[0053] (1) Prepare a web (10) containing latent crimped fibers. (2) By applying an embossing roll from one main surface (the main surface on the M side) of the web (10), multiple high-density bonding portions (103) are formed on the web (10), and the latent crimped fibers exposed on one main surface (the main surface on the M side) are heated to induce crimping. (3) The web (11) that has gone through step (2) is subjected to heat treatment to cause crimp to be formed in the latent crimp fibers contained in the web (11). This can be a method for manufacturing a nonwoven fabric (100) that includes the following steps.

[0054] Furthermore, the type of web used in step (1) can be one of those described above. By applying a water flow or needles to the web, a water-entangled web or a needle-punched web may be prepared, and this water-entangled web or needle-punched web may be submitted to the next step (2). Note that the water contained in the water-entangled web may be removed before submitting it to step (2), or some or all of it may be evaporated by applying an embossing roll in step (2).

[0055] As the embossing roll used in the above-described process (2), an embossing roll can be used which has protrusions on the surface of the roll that can heat the web (10) to form high-density bonded portions (103). The temperature of the protrusions is adjusted as appropriate so that the constituent fibers of the web (10) are melted and integrated together, forming a densely packed portion (103) that reduces the thickness of the web (10). Specifically, it is preferable to heat the protrusions to a temperature above the melting point of the resin with the lowest melting point among the resins that make up the constituent fibers. The number of protrusions on the surface of the roll may be two or more, but it is preferable to have three or more or four or more. The distribution pattern can be adjusted as appropriate, but the arrangement of the protrusions is adjusted so that recessed portions (101) with the desired distribution pattern are formed in the web (10).

[0056] As described above, the embossing roll is activated, and the latent crimped fibers exposed on one of the main surfaces (the main surface on the M side) are heated to induce crimping. Specifically, the non-embossed portion of the embossing roll (the portion of the embossing roll surface without protrusions) is heated and brought into contact with one of the main surfaces (the main surface on the M side), thereby heating the latent crimped fibers exposed on one of the main surfaces (the main surface on the M side) to induce crimping. The heating temperature of the non-embossed portion can be adjusted as appropriate, but it is preferable to heat it to a temperature above the melting point of the resin with the lowest melting point among the resins that make up the latent crimped fibers. It is preferable to induce crimping in the latent crimped fibers exposed on one of the main surfaces (the main surface on the M side) through this process, but the heating temperature and heating time of the non-embossed portion are adjusted so that crimping does not occur in all of the latent crimped fibers inside the convex portion (104).

[0057] In particular, it is preferable to heat the portion of the embossing roll surface without protrusions to a temperature equal to or higher than the melting point of the resin with the lowest melting point among the resins that make up the constituent fibers, and then bring the heated portion of the embossing roll surface without protrusions into contact with one of the main surfaces (the main surface on the M side) of the web (10). By adjusting the temperature of the portion of the embossing roll surface without protrusions in this way, some of the constituent fibers present on one of the main surfaces can be melted and bonded together. In a web manufactured in this way, the surface of the web has more constituent fibers bonded together than the interior of the web, and the surface of the web is even more resistant to deformation than the interior of the web. As a result, a difference in ease of deformation occurs between the surface and the interior of the web, making it possible to manufacture a bulkier nonwoven fabric.

[0058] Furthermore, in order to efficiently provide an even bulkier nonwoven fabric (100) with elasticity, it is preferable to adjust the heating temperature and heating time of the non-embossed portion so that crimp does not occur in all of the latent crimp fibers exposed on the other main surface (the main surface on the M' side).

[0059] The web (11) that has gone through the above-described process (2) may be used as is for the next process (3), but it is preferable to allow it to cool or chill before using it for the next process (3).

[0060] In step (3) described above, the heat treatment method and heating temperature can be appropriately selected so as to bring out the crimp of the latent crimp fibers contained in the web (11). As a heat treatment method, for example, a method of heating or heating and pressurizing with a roll can be used, a method of heating by subjecting to a heating device such as an oven dryer, far-infrared heater, dry heat dryer, or hot air dryer can be used, or a method of heating the contained organic resin by irradiating with infrared rays under no pressure can be used. The heating temperature can be adjusted as appropriate, but it is preferable to adjust it to a range that is above the temperature at which the crimp of the latent crimp fibers is brought out and below the temperature at which the constituent fibers melt. Through this step, the entire latent crimp fiber constituting the web (11) can be made to crimped fibers by bringing out the crimp.

[0061] Then, after subjecting the material to heat treatment to induce crimping of the latent crimp fibers, the nonwoven fabric (100) according to the present invention can be prepared by allowing it to cool or refrigerate.

[0062] The nonwoven fabric (100) of the present invention may further comprise other materials such as porous bodies, films, or foams. Furthermore, the nonwoven fabric (100) of the present invention may be subjected to a pressure treatment process to smooth the surface, such as a reliable press treatment. It may also be subjected to various secondary processing processes, such as a process of heat molding after punching out a shape according to the application and manner of use, a process of supporting functional components, or a hydrophilization treatment process to improve affinity with pharmaceuticals. [Examples]

[0063] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention. The physical properties of the prepared nonwoven fabric were measured by the following method.

[0064] (Method for measuring tensile strength (unit: N / 20mm)) Three test specimens measuring 80 mm in length and 20 mm in width are taken, with the production direction and the long side direction of the object to be measured parallel. These specimens are then subjected to a constant-speed elongation tensile testing machine (Orientec Co., Ltd., Tensilon, distance between chucks (grip spacing): 50 mm, tensile speed: 100 mm / min), and the specimens are stretched to measure the maximum load until the specimen breaks. This maximum load measurement is performed for all three specimens, and the arithmetic mean of these maximum loads is defined as the "tensile strength" in the MD direction.

[0065] Similarly, with the production direction and the short side direction of the object to be measured parallel, three test pieces measuring 80 mm in length and 20 mm in width are taken, and the arithmetic mean of the maximum loads measured from these pieces is defined as the "tensile strength" in the CD direction.

[0066] (Method for measuring elongation rate (Sr, unit: %)) This refers to the percentage of the elongation of the test specimen 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 percentages is taken as the "elongation rate" in the MD direction or CD direction. Sr = (Smax / 50) × 100

[0067] (Method for measuring tensile strength (unit: N / 20mm)) Three test pieces measuring 80 mm in length and 20 mm in width are taken, with the production direction and the longer side of the object to be measured parallel. The specimens obtained in this manner are subjected to a constant-speed elongation tensile testing machine (Orientec Co., Ltd., Tensilon, distance between chucks (grip spacing): 50 mm, tensile speed: 100 mm / min). The specimens are pulled, and the maximum load measured when the specimen is elongated by 10 mm (=20%) and the maximum load measured when it is elongated by 25 mm (=50%) are measured. This maximum load measurement is performed for three specimens, and the arithmetic mean of these maximum loads is defined as the "strength at 20% elongation" and "strength at 50% elongation" in the MD direction. Similarly, with the production direction and the short side direction of the object to be measured parallel, three test pieces measuring 80 mm in length and 20 mm in width were taken, and the arithmetic mean of the maximum loads measured from these pieces were defined as the "strength at 20% elongation" and the "strength at 50% elongation" in the CD direction.

[0068] (Method for measuring the recovery rate at 50% elongation (unit: %)) Three test pieces measuring 80 mm in length and 20 mm in width are taken, with the production direction and the longer side of the object to be measured parallel. The specimens collected in this manner are subjected to a constant-speed elongation tensile testing machine (Orientec Co., Ltd., Tensilon, distance between chucks (grip spacing): 50 mm, tensile speed: 100 mm / min). The starting point is the grip spacing of 50 mm, and the specimen 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 elongation (Lf) when the tensile stress of the specimen reaches 0.05 N during this pulling operation and the elongation (Lb) when the tensile stress of the specimen reaches 0.05 N during the returning operation are measured. This measurement is performed on three test specimens, and the elongations (Lf, Lb) are arithmetic mean to calculate the average elongation during tensile operation (Lfav) and the average elongation during release operation (Lbav). The value calculated from the following formula is defined as the "50% elongation recovery rate (R, in %)". R=[{(L50-Lfav)-(Lbav-Lfav)} / (L50-Lfav)]×100 Furthermore, the recovery rate at 50% elongation (%) obtained by performing the above measurement three times is defined as the "recovery rate at 50% elongation after three repetitions (unit: %)" in the CD direction. Similarly, with the production direction and the short side direction of the object to be measured parallel, three test pieces measuring 80 mm in length and 20 mm in width are taken, and the calculated value is defined as the "50% elongation recovery rate (R, unit: %)" in the CD direction. Furthermore, the recovery rate at 50% elongation (%) obtained by performing the above measurement three times is defined as the "recovery rate at 50% elongation after three repetitions (unit: %)" in the CD direction.

[0069] (Example 1) Only latent crimp fibers (side-by-side type, fiber cross-sectional shape: circular, fineness: 2.2 dtex, fiber length: 51 mm, melting point of the lower-melting-point polyester resin: 230°C) composed of two types of polyester resins with different melting points were fed into a carding machine to prepare a unidirectional web. The unidirectional web thus prepared was fed into a cross-wrapper device and folded to produce a cross-lay web (basis weight: 80 g / m²) in which the latent crimp fibers have a bidirectional fiber orientation within the main plane direction. 2 ) was prepared. An embossing roll (temperature of protrusions: 230°C, temperature of the non-protrusion areas on the embossing roll surface: 230°C) was prepared. An embossing roll was applied to one of the main surfaces (the M-side main surface) of the crosslay web to form multiple embossed areas (high-density bonded areas, with multiple circular embossed areas of equal spacing and a polka-dot pattern, each with a diameter of 2 mm, and a distance of 12 mm between the centers of the embossed areas). Simultaneously, a portion of the embossing roll surface without protrusions was brought into contact with the M-side main surface of the crosslay web to heat the latent crimped fibers present on that surface, thereby inducing crimping. Then, the cross-lay web was allowed to cool after being processed with the embossing roll. Subsequently, the crosslay web was heated in an oven dryer (heating temperature: 145°C) to bring out the crimp of the latent crimp fibers constituting the crosslay web, thereby preparing a nonwoven fabric with multiple recesses and protrusions on one main surface (with multiple circular embossed areas of equal spacing, each 2 mm in diameter, and a distance of 8 mm between the centers of the embossed areas). Furthermore, in the prepared nonwoven fabric, the crimped fibers on the surface of the convex portion had a higher crimp count than the crimped fibers inside the convex portion and the crimped fibers on the other main surface. In addition, the constituent fibers (crimped fibers) were more bonded to each other on the surface of the convex portion than inside the convex portion.

[0070] Figure 5 shows a photograph of the nonwoven fabric prepared in Example 1, taken from an oblique upward direction on one main surface, and Figure 6 shows a photograph taken from an oblique upward direction on the other main surface.

[0071] (Comparative Example 1) A metal rod with a circular tip shaped to a diameter of 2 mm was prepared. The tip of the metal rod was then heated to 230°C. Next, the heated tip of the metal rod was applied to one of the main surfaces (the main surface on the M side) of the crosslay web used in Example 1, thereby forming multiple embossed areas (high-density bonded areas, with multiple circular embossed areas of equal spacing forming a polka-dot pattern, with a distance of 12 mm between the centers of the embossed areas) on the crosslay web. Furthermore, in this process, no crimping occurred in the latent crimped fibers in the portion of one of the main surfaces of the crosslay web (the main surface on the M side) where the tip of the heated metal rod was not applied. The crosslay web was then allowed to cool after being treated with the metal rod. Subsequently, the crosslay web was heated in an oven dryer (heating temperature: 145°C) to bring out the crimp of the latent crimp fibers constituting the crosslay web, thereby preparing a nonwoven fabric (with multiple circular embossed areas of 2 mm in diameter, forming an evenly spaced polka dot pattern, with a distance of 8 mm between the centers of the embossed areas). Furthermore, in the prepared nonwoven fabric, the crimped fibers located inside the raised sections, the crimped fibers on the other main surface, and the crimped fibers on the surface of the raised sections all had the same number of crimps. In addition, the number of bonds between the constituent fibers (crimped fibers) was the same both inside and on the surface of the raised sections.

[0072] Figure 7 shows a photograph of the nonwoven fabric prepared in Comparative Example 1, taken from an oblique upward direction on one main surface, and Figure 8 shows a photograph of the other main surface, taken from an oblique upward direction.

[0073] The nonwoven fabric manufacturing method used in this comparative example is the same as in Example 1, except that the embossed portion is formed without contacting one of the main surfaces (the main surface on the M side) of the web with the portion of the embossing roll surface where there are no protrusions. This method is intended to prepare a nonwoven fabric (with multiple circular embossed areas of equal spacing, each 2 mm in diameter, and a distance of 8 mm between the centers of the embossed portions).

[0074] (Example 2) Except for changing the heating temperature of the crosslay web using an oven dryer to 160°C, a nonwoven fabric having multiple recesses and convex portions on one main surface side (multiple circular embossed areas with a diameter of 2 mm forming an evenly spaced polka dot pattern, with a distance of 7 mm between the centers of the embossed portions) was prepared in the same manner as in Example 1. Furthermore, in the prepared nonwoven fabric, the crimped fibers on the surface of the convex portion had a higher crimp count than the crimped fibers inside the convex portion and the crimped fibers on the other main surface. In addition, the constituent fibers (crimped fibers) were more bonded to each other on the surface of the convex portion than inside the convex portion.

[0075] (Example 3) Except for changing the heating temperature of the crosslay web using an oven dryer to 190°C, a nonwoven fabric having multiple recesses and convex portions on one main surface side (multiple circular embossed areas with a diameter of 2 mm forming an evenly spaced polka dot pattern, with a distance of 7 mm between the centers of the embossed portions) was prepared in the same manner as in Example 1. Furthermore, in the prepared nonwoven fabric, the crimped fibers on the surface of the convex portion had a higher crimp count than the crimped fibers inside the convex portion and the crimped fibers on the other main surface. In addition, the constituent fibers (crimped fibers) were more bonded to each other on the surface of the convex portion than inside the convex portion.

[0076] The various physical properties of each nonwoven fabric prepared as described above were evaluated and summarized in Table 1.

[0077] [Table 1]

[0078] The nonwoven fabric of Example 1 satisfied the configuration of the present invention and was a bulky nonwoven fabric with excellent elasticity (e.g., elongation rate (%)). In contrast, the nonwoven fabric of Comparative Example 1 did not satisfy the configuration of the present invention and was a nonwoven fabric inferior in elasticity (e.g., elongation rate (%)) and bulkiness.

[0079] Furthermore, the nonwoven fabrics of Examples 2 and 3, which had a larger basis weight than Example 1, also satisfied the configuration of the present invention and were bulky nonwoven fabrics with high elasticity (e.g., elongation rate (%)).

[0080] (Example 4) Only latent crimp fibers (side-by-side type, fiber cross-sectional shape: circular, fineness: 2.2 dtex, fiber length: 51 mm, melting point of the lower-melting-point polyester resin: 230°C) composed of two polyester resins with different melting points were fed into a carding machine to prepare a unidirectional web. The unidirectional web thus prepared was fed into a cross-wrapper device and folded to produce a cross-lay web (basis weight: 40 g / m²) in which the latent crimp fibers have a bidirectional fiber orientation within the main plane direction. 2 ) was prepared. Next, the crosslay web was subjected to a water-jet entanglement device, where a water flow was applied to strongly entangle the constituent fibers of the crosslay web. After that, the water-jet entangled web was dried naturally at room temperature to remove the moisture contained in it. An embossing roll (temperature of protrusions: 230°C, temperature of the non-protrusion areas on the embossing roll surface: 230°C) was prepared. After being subjected to a water-flow entanglement device, an embossing roll was applied to one main surface (the main surface on the M side) of the crosslay web (hereinafter referred to as the water-flow entanglement web) to form multiple embossed portions (high-density bonded portions, consisting of multiple circular embossed areas with a diameter of 2 mm and an evenly spaced dot pattern, with a distance of 12 mm between the centers of the embossed portions) on the water-flow entanglement web. Simultaneously, a portion of the embossing roll surface without protrusions was brought into contact with one main surface (the main surface on the M side) of the water-flow entanglement web to heat the latent crimped fibers present on that main surface, thereby inducing crimping. Then, the water-entangled web, after being processed with the embossing roll, was allowed to cool. Subsequently, the water-entangled web was heated in an oven dryer (heating temperature: 180°C) to bring out the crimp of the latent crimped fibers constituting the water-entangled web, thereby preparing a nonwoven fabric with multiple recesses and protrusions on one main surface (with multiple circular embossed areas of equal spacing, each 2 mm in diameter, and a distance of 8 mm between the centers of the embossed areas). Furthermore, in the prepared nonwoven fabric, the crimped fibers on the surface of the convex portion had a higher crimp count than the crimped fibers inside the convex portion and the crimped fibers on the other main surface. In addition, the constituent fibers (crimped fibers) were more bonded to each other on the surface of the convex portion than inside the convex portion.

[0081] (Comparative Example 2) A metal rod with a circular tip shaped to a diameter of 2 mm was prepared. The tip of the metal rod was then heated to 230°C. Next, the heated tip of the metal rod was applied to one of the main surfaces (the main surface on the M side) of the water-entangled web used in Example 4 after the water had been removed, thereby forming multiple embossed portions (high-density bonding portions, with multiple circular embossings of 2 mm in diameter forming an evenly spaced water-dot pattern, and the distance between the centers of the embossed portions: 12 mm) on the water-entangled web. Furthermore, in this process, no crimping occurred in the latent crimped fibers in the portion of one of the main surfaces (the M-side main surface) of the water-entangled web that was not treated with the heated metal rod. The water-entangled web was then allowed to cool after being treated with the metal rod. Subsequently, the water-entangled web was heated in an oven dryer (heating temperature: 175°C) to bring out the crimp of the latent crimped fibers constituting the water-entangled web, thereby preparing a nonwoven fabric (with a polka-dot pattern at equal intervals and multiple circular embossings with a diameter of 2 mm, and a distance of 8 mm between the centers of the embossed parts). Furthermore, in the prepared nonwoven fabric, the crimped fibers located inside the raised sections, the crimped fibers on the other main surface, and the crimped fibers on the surface of the raised sections all had the same number of crimps. In addition, the number of bonds between the constituent fibers (crimped fibers) was the same both inside and on the surface of the raised sections.

[0082] The nonwoven fabric manufacturing method used in this comparative example is the same as in Example 4, except that the embossed portion is formed without contacting one of the main surfaces (the main surface on the M side) of the web with the portion of the embossing roll surface where there are no protrusions. This method is intended to prepare a nonwoven fabric (with multiple circular embossed areas of equal spacing, each 2 mm in diameter, and a distance of 8 mm between the centers of the embossed portions).

[0083] The various physical properties of each nonwoven fabric prepared as described above were evaluated and summarized in Table 2.

[0084] [Table 2]

[0085] The nonwoven fabric of Example 4 satisfied the structure of the present invention and was a bulky nonwoven fabric. In contrast, the nonwoven fabric of Comparative Example 2 did not satisfy the structure of the present invention and was a nonwoven fabric with inferior bulkiness. [Industrial applicability]

[0086] The nonwoven fabric of the present invention can be used to provide components for medical and hygiene products such as diaper waistbands and leg openings, supporters and bandages, adhesive medicinal bases and plaster bases, and facial masks. It can also be suitably used in other industrial applications where stretchability, bulkiness, or cushioning properties are required. [Explanation of Symbols]

[0087] 1. Absorbent sheet for absorbent materials 2. Embossed section 3...stretch area 100... Nonwoven fabric having two main surfaces containing crimped fibers in its constituent fibers. 101...Multiple recessed areas 102...Convex portion located between adjacent concave portions 103...High-density areas 104...The portion enclosed by both main surfaces and adjacent recesses. 105... Surface of the convex portion M... One of the main sides M'···The other main side 10. Web containing latent crimped fibers 11. Web after embossing roll has been applied.

Claims

1. The constituent fibers consist of only one type of crimped fiber, and the nonwoven fabric has two exposed main surfaces. One main surface has a plurality of recessed portions and convex portions located between adjacent recessed portions. In the recessed portion, the constituent fibers are bonded together. The crimped fibers on the surface of one of the main surfaces have a greater number of crimps than the crimped fibers on the surface of the convex portion that are surrounded by the two main surfaces and the adjacent concave portions. Nonwoven fabric.

2. (1) A step of preparing a web in which the constituent fibers consist of only one type of latent crimp fiber, (2) A step of forming a plurality of high-density bonded portions on the web by applying an embossing roll from one main surface of the web, and heating the latent crimped fibers exposed on the one main surface to cause crimping, (3) A step of subjecting the web that has gone through step (2) to heat treatment in order to cause crimp to appear in the latent crimp fibers contained in the web, A method for producing a nonwoven fabric according to claim 1, comprising:

Images