Extensible wet-laid nonwoven fabric

Abstract

To provide an extensible wet nonwoven fabric without a wrinkle or without a noticeable wrinkle.SOLUTION: In the extensible wet nonwoven fabric, an elongation rate at least in one direction is 30% or more, and a variation in a dynamic friction coefficient of at least one main face thereof is less than 0.04. A tensile strength at least in one direction preferably is preferably 3 N / (50 mm width) or more. The extensible wet nonwoven fabric preferably contains a crimped fiber or an adhesive fiber as a constituent fiber, and particularly preferably contains both the crimped fiber and the adhesive fiber.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an extensible wet-laid nonwoven fabric that is wrinkle-free or wrinkle-free. [Background technology]

[0002] Since extensible nonwoven fabrics can be easily deformed by external forces, they can be suitably used in various applications. In particular, extensible wetlaid nonwoven fabrics have fibers uniformly dispersed compared to extensible drylaid nonwoven fabrics, and are expected to have excellent texture, and therefore have been expected to be used in various applications.

[0003] For example, if a nonwoven fabric used as a surface material for automobile ceiling materials has extensibility, it can be easily thermoformed to fit the shape of the automobile ceiling, but if the nonwoven fabric used as the surface material has wrinkles, the wrinkles are amplified during thermoforming, resulting in a significant deterioration in appearance quality. Also, surface materials that add design by applying a print to the surface material of automobile ceiling materials are known, but if the nonwoven fabric used as the surface material has wrinkles, the wrinkles are stretched during thermoforming, resulting in an unintended printed pattern, resulting in a significant deterioration in appearance quality.

[0004] In addition, patches that provide anti-inflammatory and analgesic effects, cosmetic effects, or a warm or cool sensation are applied to the human body and are stretched by the human body to some extent, so if the nonwoven fabric used as the base material of the patch has stretchability, the wearer is less likely to feel uncomfortable, which is preferable, but if the base material nonwoven fabric is wrinkled, not only will the appearance quality be poor, but when the patch is applied, clothes, etc., are likely to get caught on the nonwoven fabric base material exposed on the outside, and it is likely to peel off. In addition, post-processing such as water-repellent processing is sometimes performed on the nonwoven fabric base material of the patch, but unprocessed areas are generated in the gaps between the wrinkles, and when the gaps between the wrinkles are exposed to the surface due to stretching during use, the performance of the post-processing (for example, water repellency) cannot be fully demonstrated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-019094 A (Claim 5,

[0001] ,

[0053] , etc.) Summary of the Invention [Problem to be solved by the invention]

[0006] As an example of a wetlaid nonwoven fabric having such extensibility, JP 2009-019094 A (Patent Document 1) discloses a wetlaid nonwoven fabric formed by mixing a heat-adhesive composite binder fiber and a latent shrinkable polyester composite fiber in a mass ratio of 10 / 90 to 50 / 50. Specifically, it discloses that the heat-adhesive composite binder fiber and the latent shrinkable composite fiber are mixed and stirred and mixed in a pulp disintegrator, and then a dispersing oil is added and the mixture is made in a papermaking machine to obtain a wetlaid nonwoven fabric web, and then hot air is applied to the low-melting polyester resin constituting the heat-adhesive composite binder fiber to produce a wetlaid nonwoven fabric. However, because the wetlaid nonwoven web is dense, the latent crimpable polyester conjugate fibers are unable to uniformly develop crimps when hot air is applied to the wetlaid nonwoven web, resulting in a wrinkled wetlaid nonwoven fabric, and it was thought that this wetlaid nonwoven fabric had the problems described above.

[0007] The present invention has been made to solve these problems, and has an object to provide an extensible wetlaid nonwoven fabric which is wrinkle-free or wrinkle-inconspicuous. [Means for solving the problem]

[0008] [1] The present invention relates to an extensible wetlaid nonwoven fabric having an elongation rate of 30% or more in at least one direction, the extensible wetlaid nonwoven fabric being characterized in that the variation in the dynamic friction coefficient on at least one of the main surfaces of the extensible wetlaid nonwoven fabric is less than 0.04.

[0009] [2] Another invention is "the extensible wetlaid nonwoven fabric according to [1], characterized in that the tensile strength in at least one direction is 3 N / (50 mm width) or more, preferably 5 N / (50 mm width) or more."

[0010] [3] Yet another invention is the extensible wetlaid nonwoven fabric according to [1] or [2], characterized in that the fibers constituting the extensible wetlaid nonwoven fabric include crimped fibers, for example, crimped fibers consisting of latent crimped fibers in which crimping has occurred, or manifestly crimped fibers in which crimping has occurred.

[0011] [4] Yet another invention is "the extensible wetlaid nonwoven fabric according to any one of [1] to [3], characterized in that the fibers constituting the extensible wetlaid nonwoven fabric include adhesive fibers." Effect of the Invention

[0012] The invention of [1] is an extensible wetlaid nonwoven fabric having a variation in the dynamic friction coefficient on at least one of its main surfaces of less than 0.04, which has no or inconspicuous wrinkles, has excellent appearance quality, can exhibit uniform performance in post-processing even when post-processing is performed, and is less likely to get caught depending on the intended use, etc., and has various other effects.

[0013] The invention [2] is an extensible wetlaid nonwoven fabric having a tensile strength in at least one direction of 3 N / (50 mm width) or more, preferably 5 N / (50 mm width) or more, which is easy to handle and can be easily used for various purposes.

[0014] The invention of [3] is an extensible wetlaid nonwoven fabric that has excellent stretchability as well as extensibility because it contains crimped fibers such as latent crimped fibers that have exhibited crimp and manifested crimped fibers.

[0015] The invention of [4] is a stretchable wet-laid nonwoven fabric having excellent strength because it contains adhesive fibers. [Brief description of the drawings]

[0016] [Figure 1] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 1 of the present invention taken with a digital camera. [Diagram 2]A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 2 of the present invention taken with a digital camera. [Diagram 3] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 3 of the present invention taken with a digital camera. [Figure 4] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 4 of the present invention taken with a digital camera. [Diagram 5] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 5 of the present invention taken with a digital camera. [Figure 6] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 6 of the present invention taken with a digital camera. [Figure 7] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 7 of the present invention taken with a digital camera. [Figure 8] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Comparative Example 1 of the present invention taken with a digital camera. [Figure 9] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Comparative Example 2 of the present invention taken with a digital camera. [Figure 10] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 8 of the present invention taken with a digital camera. [Figure 11] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Example 9 of the present invention taken with a digital camera. [Figure 12] A photograph of one of the main surfaces of the extensible wetlaid nonwoven fabric produced in Comparative Example 3 of the present invention taken with a digital camera. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The extensible nonwoven fabric of the present invention is a wet-laid nonwoven fabric in which the fibers are uniformly dispersed. The wet-laid nonwoven fabric is a nonwoven fabric formed by forming a wet-laid fiber web using a liquid such as water as a dispersion medium for the fibers, and then bonding the fibers constituting the wet-laid fiber web together.

[0018] The fibers constituting the extensible wetlaid nonwoven fabric of the present invention are preferably composed of fibers having a fiber length of 30 mm or less so that the fibers are uniformly dispersed, and since the shorter the fiber length, the higher the degree of freedom of the fibers and the more uniformly dispersed the fibers are, the fiber length is preferably 25 mm or less, more preferably 20 mm or less, even more preferably 15 mm or less, and even more preferably 10 mm or less. On the other hand, the fiber length is preferably 0.1 mm or more so that the extensible wetlaid nonwoven fabric has strength and excellent handling properties.

[0019] The fiber length can be measured by the following procedure. First, 20 fibers of each fiber type are pulled out from the extensible wetlaid nonwoven fabric. The 20 pulled fibers are fixed with tape onto a support that allows the fibers to be identified (e.g., a black mount for white fibers) so that each fiber is straight, and the length of each fiber is measured. The arithmetic average of the lengths of each fiber is then taken as the fiber length of that fiber type.

[0020] The fibers constituting the extensible wetlaid nonwoven fabric of the present invention are not particularly limited, but preferably contain crimped fibers made of latent crimped fibers that have been crimped. This is because the extensible wetlaid nonwoven fabric contains crimped fibers made of latent crimped fibers that have been crimped, and thereby has stretchability in addition to extensibility.

[0021] When the wetlaid fiber web contains crimped fibers made of latent crimped fibers that have been subjected to crimping, the latent crimped fibers contained in the wetlaid fiber web become entangled with adjacent fibers when they are subjected to crimping, and the fibers can be brought into close contact with each other, so that the wetlaid nonwoven fabric can have a dense structure without wrinkles or without noticeable wrinkles. In addition, the inclusion of crimped fibers made of such latent crimped fibers that have been subjected to crimping also provides the effect of excellent flexibility and abrasion resistance, and is less likely to fluff.

[0022] The fiber diameter of the latent crimped fiber is not particularly limited, but since a small fiber diameter tends to make wrinkles less noticeable and tends to make the fibers more likely to become entangled, the fiber diameter is preferably 18 μm or less, more preferably 15 μm or less, even more preferably 12 μm or less, even more preferably 11 μm or less, even more preferably 10 μm or less, even more preferably 9 μm or less, and even more preferably 8 μm or less. The lower limit of the fiber diameter of the latent crimped fiber is not particularly limited, but it is preferably 0.1 μm or more.

[0023] In the present invention, the "fiber diameter" refers to the diameter of a fiber when the cross-sectional shape is circular, and when the cross-sectional shape is other than circular, the fiber diameter is regarded as the diameter of a circle having the same area as the cross-sectional area.

[0024] Examples of such latent crimp fibers include: (1) composite fibers in which multiple resins with different thermal shrinkage rates are combined in an eccentric core-sheath or side-by-side configuration, and which exhibit crimp when exposed to heat; (2) fibers in which a portion of the fiber is subjected to a specific thermal history, and which exhibit crimp when exposed to heat; and (3) eccentric hollow fibers that are made of a single type of resin component but have a hollow portion extending in an eccentric state in the longitudinal direction of the fiber, and which exhibit crimp when exposed to heat.

[0025] Examples of the resin combination of the composite fiber (1) include polyester-copolyester, polyamide-copolyamide, polyester-polyamide, polyester-polypropylene, polypropylene-copolypropylene, polypropylene-polyethylene, etc. When chemical resistance, flexibility and / or stretchability are required for the extensible wetlaid nonwoven fabric of the present invention, latent crimp fibers made of a combination of polyester-copolyester or polypropylene-low melting point polypropylene are preferred.

[0026] As the latent crimped fiber in which a part of the fiber (2) has been subjected to a specific heat history, for example, a fiber made of a thermoplastic resin such as polyester or polyamide, which has been passed over one side with a hot blade or the like, can be used.

[0027] Furthermore, the eccentric hollow fiber (3) can be made of a thermoplastic resin such as polyester, polypropylene, or polyamide.

[0028] In this way, when the fabric contains crimped fibers made of latent crimped fibers that have developed crimp, the fabric can have stretchability in addition to extensibility, but when the fabric contains manifest crimped fibers that originally have crimp, the fabric can have stretchability in addition to extensibility. In particular, a stretchable wet nonwoven fabric produced by using manifest crimped fibers that originally have crimp in addition to latent crimped fibers tends to have fewer or less noticeable wrinkles, so it is preferable to contain manifest crimped fibers in addition to crimped fibers made of latent crimped fibers that have developed crimp.

[0029] The fiber diameter of the apparently crimped fiber is not particularly limited, but in order to make wrinkles less noticeable, and particularly when using it in combination with a latent crimped fiber to produce an extensible wet-laid nonwoven fabric, the fiber diameter is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, so that the voids in which the latent crimped fiber can be expressed during the production of the extensible wet-laid nonwoven fabric are secured by the apparently crimped fiber, so that wrinkles in the extensible wet-laid nonwoven fabric are less noticeable. On the other hand, if the fiber diameter of the apparently crimped fiber is too large, it tends to disturb the texture of the extensible wet-laid nonwoven fabric, so the fiber diameter is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and even more preferably 20 μm or less.

[0030] Such a manifested crimp fiber may be a fiber in which the crimp of the latent crimp fiber described above is expressed, or may be a fiber produced by compounding, such as bonding together, resins of the same composition or different compositions with different degrees of polymerization (viscosity) during spinning. The manifested crimp fiber may also be a fiber produced by unevenly distributing hollow parts during spinning. Alternatively, it may be a fiber to which crimp has been imparted by false twist processing, mechanical pressing processing, or jet pressing processing. Note that the crimp of the manifested crimp fiber imparted with crimp by mechanical pressing processing is planar (two-dimensional), while the crimp of the other manifested crimp fiber is three-dimensional (three-dimensional), and has excellent stretchability, so it is preferable that the manifested crimp fiber has a three-dimensional crimp.

[0031] When the manifestly crimped fiber is a composite fiber, the resin that constitutes the manifestly crimped fiber may be a combination of resins similar to those of the latent crimped fiber. When chemical resistance, flexibility and / or stretchability are required for the extensible wetlaid nonwoven fabric, it is preferable for the resin to be a combination of polyester-copolyester or polypropylene-low melting point polypropylene.

[0032] In addition, when the actually crimped fiber is a fiber in which resins of the same composition but different degrees of polymerization (viscosity) are combined during spinning, when the hollow portion is unevenly distributed during spinning, or when the fiber is a fiber in which crimping has been imparted by false twist processing, mechanical pressing processing, or jet pressing processing, it can be composed of resins such as polyester, polypropylene, polyamide, and polyacrylonitrile.

[0033] In this way, the extensible wetlaid nonwoven fabric of the present invention preferably contains crimped fibers such as latent crimped fibers that have been crimped or manifestly crimped fibers that have been crimped to begin with, and the number of crimps of the crimped fibers is preferably 3 / 25 mm or more, more preferably 4 / 25 mm or more, and even more preferably 5 / 25 mm or more so that the wrinkles of the extensible wetlaid nonwoven fabric are not noticeable and the extensibility, particularly stretchability, is excellent. Also, the crimp rate of the crimped fibers is preferably 4% or more, more preferably 5% or more, and even more preferably 7% or more so that the wrinkles of the extensible wetlaid nonwoven fabric are not noticeable.

[0034] The crimp number and crimp percentage of the crimped fiber constituting the extensible wetlaid nonwoven fabric of the present invention can be measured by the following procedure. First, 20 crimped fibers of each type of crimped fiber are pulled out from the extensible wetlaid nonwoven fabric, and the crimp number of the pulled out crimped fibers is measured in accordance with JIS 1015:2010 "Test method for chemical fiber staples" 8.12.1 (crimp number) with a gripping distance of 1 / 2 the fiber length of the crimped fiber. In addition, the crimp percentage of the crimped fiber is measured by measuring the crimp percentage of the pulled out crimped fiber according to the crimp percentage specified in JIS 8.12.2 (crimp percentage and residual crimp percentage).

[0035] Another extensible wetlaid nonwoven fabric of the present invention contains adhesive fibers, and by being bonded, it is expected that in addition to improving the strength, the effect of preventing fibers from falling off from the extensible wetlaid nonwoven fabric due to friction can be expected. In addition, when the extensible wetlaid nonwoven fabric is produced by entangling a wetlaid fiber web with a fluid flow such as a water flow, if the adhesive fibers are bonded before entangling with the fluid flow, the adhesive fibers are bonded to the surrounding fibers and integrated with them, so that the apparent fiber length becomes longer and the ratio (fiber length / fiber diameter) (aspect ratio) increases, thereby increasing the strength of the wetlaid fiber web, and since the entanglement process can be performed without destroying the fiber web itself, the texture of the wetlaid fiber web is not significantly disturbed.

[0036] The fiber diameter of the adhesive fiber is not particularly limited, but since a smaller fiber diameter leads to better dispersion of the adhesive fiber and a wrinkle-free extensible wet-laid nonwoven fabric, the fiber diameter of the adhesive fiber is preferably 18 μm or less, more preferably 15 μm or less, even more preferably 12 μm or less, even more preferably 11 μm or less, even more preferably 10 μm or less, even more preferably 9 μm or less, and even more preferably 8 μm or less. The lower limit of the fiber diameter of the adhesive fiber is not particularly limited, but it is preferably 0.1 μm or more.

[0037] In addition, when the adhesive fiber has crimp, the adhesive fiber acts similarly to a crimped fiber. In the case of the adhesive fiber having crimp, the crimp may be a three-dimensional crimp or a planar (two-dimensional) mechanical crimp imparted by a stuffing box type crimper or the like.

[0038] Such adhesive fibers can be full melt type fibers, or composite fibers such as core-sheath type, sea-island type, and side-by-side type in which the low melting point component is exposed on the surface of the fiber. When the adhesive fibers are composite fibers, the fiber shape can be maintained during melt bonding of the low melting point component, so that an extensible wet-laid nonwoven fabric with superior strength can be obtained. The components other than the low melting point component (high melting point components) of the adhesive fibers made of composite fibers preferably have a melting point 5°C or higher than that of the low melting point component, more preferably 10°C or higher, and even more preferably 15°C or higher, so that the fiber shape can be maintained during melt bonding of the low melting point component.

[0039] The adhesive fiber can be made of a thermoplastic resin, and in the case of a full melt type, examples of the combination of resins include polyester, copolymerized polyester, polyamide, copolymerized polyamide, polypropylene, copolymerized polypropylene, polyethylene, copolymerized polyethylene, etc. On the other hand, examples of the combination of resins in the case where the adhesive fiber is made of a composite fiber include polyester-copolymerized polyester, polyester-polyamide, polyester-copolyamide, polyester-polypropylene, polyester-copolypropylene, polyester-polyethylene, polyester-copolyethylene, polyamide-copolymerized polyester, polyamide-copolyamide, polyamide-polypropylene, polyamide-copolyethylene, polypropylene-copolypropylene, polypropylene-polyethylene, polypropylene-copolyethylene, polyethylene-copolyethylene, etc.

[0040] When the extensible wetlaid nonwoven fabric of the present invention contains the crimped fiber made of the latent crimped fiber and the adhesive fiber, it is a suitable combination because it has a good balance between extensibility and strength.When the extensible wetlaid nonwoven fabric of the present invention contains the crimped fiber made of the latent crimped fiber and the adhesive fiber, it is preferable that the crimped fiber made of the latent crimped fiber and the adhesive fiber are contained in a mass ratio of 99:1 to 50:50, more preferably 95:5 to 60:40, and even more preferably 90:10 to 70:30, so as to have a good balance between extensibility and strength.

[0041] When the extensible wetlaid nonwoven fabric of the present invention contains visibly crimped fibers, it is easy to obtain an extensible wetlaid nonwoven fabric without or with inconspicuous wrinkles by having visibly crimped fibers account for 20 mass% or more of the total fibers constituting the extensible wetlaid nonwoven fabric. More preferably, visibly crimped fibers account for 30 mass% or more of the total fibers constituting the extensible wetlaid nonwoven fabric, and even more preferably, visibly crimped fibers account for 40 mass% or more of the total fibers constituting the extensible wetlaid nonwoven fabric. On the other hand, since it is preferable to contain crimped fibers consisting of latent crimped fibers that have expressed crimp so as to have excellent elasticity, it is preferable that the visibly crimped fibers account for 80 mass% or less of the total fibers constituting the extensible wetlaid nonwoven fabric, more preferably 70 mass% or less, and even more preferably 60 mass% or less. As mentioned above, the adhesive fiber can have crimp. When the adhesive fiber has crimp, it is preferable that the adhesive fiber is regarded as a visibly crimped fiber, and the total amount of the visibly crimped fiber that is also an adhesive fiber and the visibly crimped fiber that is not an adhesive fiber satisfies the above-mentioned mass ratio.

[0042] In addition, when the extensible wetlaid nonwoven fabric of the present invention contains crimped fibers made of latent crimped fibers that have been crimped, manifested crimped fibers, and adhesive fibers, it is a suitable combination because there are no or inconspicuous wrinkles and the balance between extensibility and strength is excellent. In this case, in order to have excellent effects, it is preferable to contain the crimped fibers made of latent crimped fibers that have been crimped, the manifested crimped fibers, and the adhesive fibers in a mass ratio of 10-70:20-80:10-70, more preferably in a mass ratio of 20-70:20-70:10-60, and even more preferably in a mass ratio of 30-70:20-60:10-50. As mentioned above, the adhesive fibers can have crimps, but even if the adhesive fibers have crimps, it is preferable that the amount of the adhesive fibers satisfies the above mass ratio.

[0043] Furthermore, the extensible wetlaid nonwoven fabric of the present invention may contain fine fibers having a fiber diameter of 6 μm or less. By containing such fine fibers, the structure can be made denser, and the extensible wetlaid nonwoven fabric can be made wrinkle-free or wrinkle-free. Since the smaller the fiber diameter of the fine fibers, the better the above-mentioned effect, the fiber diameter of the fine fibers is preferably 5 μm or less, more preferably 4.5 μm or less, even more preferably 4 μm or less, and even more preferably 3 μm or less. The lower limit of the fiber diameter of the fine fibers is not particularly limited, but it is preferably 0.1 μm or more.

[0044] Such fine fibers may be, for example, commercially available fine fibers (e.g., Tepyrus (registered trademark)), fine fibers formed by a melt-blowing method, or fine fibers generated from splittable fibers that can be split by physical and / or chemical treatments formed by a mixed spinning method or a composite spinning method. Among these, commercially available fine fibers or fine fibers generated from splittable fibers are preferable because they have excellent fiber strength due to being subjected to a mechanical stretching treatment, and the abrasion resistance of the extensible wet-laid nonwoven fabric is excellent. Examples of physical treatments for splitting splittable fibers include, for example, a fluid flow such as a water flow, a needle, a calendar, etc., and examples of chemical treatments include, for example, dissolving and removing the resin component with a solvent, and peeling due to swelling of the resin component with a solvent, etc.

[0045] The resin component constituting such fine fibers varies depending on the intended use of the extensible wetlaid nonwoven fabric, and is not particularly limited, but may be, for example, regenerated fibers such as rayon and cupra; semi-synthetic fibers such as acetate and promix; synthetic fibers such as nylon, vinylon, vinylidene, polyvinyl chloride, polyester, acrylic, polyethylene, polypropylene, and polyurethane; vegetable fibers such as cotton and hemp, and animal fibers such as wool and silk.

[0046] Further, the extensible wetlaid nonwoven fabric of the present invention may contain regular fibers having a fiber diameter of more than 6 μm. These regular fibers may be made of the same resin components as those that can be used to make up the fine fibers.

[0047] The extensible wetlaid nonwoven fabric of the present invention can be composed of, for example, crimped fibers consisting of latent crimped fibers that have expressed crimp as described above, manifested crimped fibers, adhesive fibers, fine fibers and / or regular fibers, and the cross-sectional shape of these fibers is not particularly limited, and can be, for example, a perfect circle, an oval, an ellipse, a polygon (for example, a triangular shape, a rectangular shape, a trapezoidal shape or other quadrangular shape, a pentagonal shape, a hexagonal shape, etc.), or an alphabet shape (for example, an E shape, an F shape, an H shape, an I shape, a K shape, an L shape, an M shape, an N shape, a T shape, an X shape, a Y shape, etc.).

[0048] Furthermore, the crimped fibers, apparent crimped fibers, adhesive fibers, fine fibers and / or regular fibers made of latent crimped fibers in which crimping has been expressed as described above may be white, or may be colored in a color other than white with a pigment and / or dye.

[0049] The extensible wetlaid nonwoven fabric of the present invention can be composed of the fibers described above, and since the smaller the average fiber diameter of the fibers constituting the extensible wetlaid nonwoven fabric, the denser the structure and the less or less noticeable the wrinkles tend to be, the average fiber diameter of the fibers constituting the extensible wetlaid nonwoven fabric is preferably 18 μm or less, more preferably 15 μm or less, even more preferably 12 μm or less, even more preferably 11 μm or less, even more preferably 10 μm or less, even more preferably 9 μm or less, and even more preferably 8 μm or less. The lower limit of the average fiber diameter of the fibers constituting the extensible wetlaid nonwoven fabric is not particularly limited, but is preferably 0.1 μm or more.

[0050] The "average fiber diameter" in the present invention is a value obtained by the following method. (1) Total fiber length of each type of fiber (Lt1, Lt2, ..., Lt n ) are calculated respectively. (2) From the total fiber length of each type of fiber in (1), the total fiber length of all the fibers constituting the extensible wet-laid nonwoven fabric (= Ltt = Lt1 + Lt2 + + Lt n ) is calculated. (3) The ratio of the total fiber length of each type of fiber to the total fiber length (=Ltt) of all fibers constituting the extensible wet-laid nonwoven fabric (Rl1=Lt1 / Ltt, Rl2=Lt2 / Ltt, . . ., Rl n =Lt n / Ltt) are calculated respectively. (4) Fiber diameters of each type of fiber (D1, D2, . . ., D n ) and (3) the ratio of the total fiber length of each type of fiber (Rl1, Rl2, . . ., Rl n ) The value obtained by the following formula is the average fiber diameter (Da). Da = D1 × Rl1 + D2 × Rl2 + + D n ×Rl n

[0051] The extensible wetlaid nonwoven fabric of the present invention literally has extensibility, and since the extensibility in at least one direction is 30% or more, it has excellent moldability and can be applied to applications requiring extensibility. Since the higher the extensibility, the better the performance, the extensibility in at least one direction is preferably 40% or more, more preferably 50% or more, even more preferably 60% or more, and even more preferably 70% or more. Although there is no particular upper limit for the extensibility, if the extensibility is too high, the shape stability tends to be poor, so it is preferably 400% or less, more preferably 350% or less, even more preferably 300% or less, even more preferably 275% or less, and even more preferably 250% or less.

[0052] The direction in which the extensible wetlaid nonwoven fabric of the present invention exhibits the above-mentioned elongation is not particularly limited, but generally, tension is applied in the production direction (sometimes called the "warp direction") in the production of wetlaid nonwoven fabrics, and as a result, the fibers tend to be oriented in the production direction, and as a result, the bonds between the fibers in the direction perpendicular to the production direction (sometimes called the "transverse direction") of the extensible wetlaid nonwoven fabric tend to be weak and the fabric tends to be structurally easy to elongate, so that the elongation in the transverse direction is preferably within the above-mentioned range. Note that, since extensibility is often required in both the warp and transverse directions, such as when forming an extensible wetlaid nonwoven fabric, the elongation in both the warp and transverse directions is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and even more preferably 50% or more.

[0053] This elongation rate (Sr, unit: %) is a value calculated by the following procedure. (1) Three rectangular sample pieces, each 50 mm wide and 250 mm long, are taken from the extensible wet-laid nonwoven fabric. (2) Using a constant-speed extension tensile tester (Tensilon, manufactured by Orientec Co., Ltd.), the rectangular specimen is pulled in the long side direction, and the elongation (Smax, unit: mm) [= (length at maximum load, unit: mm) - (grip interval = 200 mm)] at the maximum load until the specimen breaks is measured. The measurement is performed under the conditions of a grip interval of 200 mm and a pulling speed of 500 mm / min. (3) Calculate the percentage of the elongation at the maximum load in (2) relative to the gripping distance (200 mm) (see the following formula). Sr = (Smax / 200) x 100 (4) The percentage of the elongation relative to the gripping distance at the maximum load in (3) is calculated for three test pieces, and the percentages of the elongation relative to the gripping distance at the maximum load are arithmetically averaged. This value is the "elongation rate" in the present invention.

[0054] The extensible wet nonwoven fabric of the present invention has the extensibility with the above-mentioned elongation rate, but the variation of the dynamic friction coefficient on at least one of the main surfaces of the extensible wet nonwoven fabric is less than 0.04. The dynamic friction coefficient indicates the slipperiness of the main surface of the extensible wet nonwoven fabric, and a large variation in the dynamic friction coefficient means a large change in the state of the main surface of the extensible wet nonwoven fabric, and it has been found that there is a correlation between the variation in the dynamic friction coefficient and the presence or absence of wrinkles. In other words, the present invention has found that when the variation in the dynamic friction coefficient is less than 0.04, the extensible wet nonwoven fabric does not have wrinkles or the wrinkles are not noticeable. The smaller the variation in the dynamic friction coefficient, the smaller the change in the state of the main surface of the extensible wet nonwoven fabric, and the less wrinkles there are or the less noticeable wrinkles, so it is preferable that the variation in the dynamic friction coefficient is 0.03 or less. The lower limit of the variation in the dynamic friction coefficient is 0, where there is absolutely no change in the state of the main surface of the extensible wetlaid nonwoven fabric.

[0055] In order for the extensible wetlaid nonwoven fabric of the present invention to have excellent abrasion resistance, it is preferable that the dynamic friction coefficient of at least one of the main surfaces of the extensible wetlaid nonwoven fabric is small. Specifically, the dynamic friction coefficient is preferably 0.5 or less, more preferably 0.4 or less, even more preferably 0.3 or less, and even more preferably 0.2 or less. The lower limit of the dynamic friction coefficient is not particularly limited, but is greater than 0. The main surface having a dynamic friction coefficient of 0.5 or less may be the same as or different from the main surface having the variation in the dynamic friction coefficient of less than 0.04, but if they are the same, the main surface is wrinkle-free and has excellent abrasion resistance, so this main surface can be used in a manner that it is exposed to the outside, which is preferable.

[0056] This "dynamic friction coefficient" is a value obtained based on JIS K 7125-ISO8295, and specifically, the dynamic friction coefficient is calculated from the dynamic friction force obtained by tracing 30 mm of the main surface of the extensible wet nonwoven fabric at a speed of 5 mm / sec while applying a load of 100 g to a metal contact terminal (area: 1 cm2) using a static and dynamic friction measuring device (manufactured by Trinity Lab Co., Ltd., product number: TL201Tt). In addition, the "variation in the dynamic friction coefficient" is calculated by calculating the standard deviation of the dynamic friction coefficient based on the data obtained from the measurement of the dynamic friction coefficient, and this standard deviation is defined as the "variation in the dynamic friction coefficient."

[0057] In the extensible wetlaid nonwoven fabric of the present invention, it is sufficient that at least one of the main surfaces of the extensible wetlaid nonwoven fabric has a main surface that satisfies the variation in dynamic friction coefficient as described above, and when the extensible wetlaid nonwoven fabric of the present invention is used, it is sufficient that the main surface that satisfies the variation in dynamic friction coefficient as described above is exposed.

[0058] The extensible wetlaid nonwoven fabric of the present invention has excellent handling properties and is preferably 3N / (50mm width) or more in at least one direction so as to be easily applicable to various uses. The stronger the tensile strength, the less likely problems such as breakage will occur during use, so it is more preferably 5N / (50mm width) or more, even more preferably 10N / (50mm width) or more, even more preferably 15N / (50mm width) or more, even more preferably 20N / (50mm width) or more, even more preferably 25N / (50mm width) or more, and even more preferably 30N / (50mm width) or more. There is no particular upper limit to the tensile strength, but if the tensile strength is too strong, the extensible wetlaid nonwoven fabric tends to become hard, which may limit the applicable uses, so it is preferably 300N / (50mm width) or less, and more preferably 280N / (50mm width) or less.

[0059] The direction in which the extensible wetlaid nonwoven fabric of the present invention exhibits the tensile strength is not particularly limited, but generally, tension is applied in the production direction (warp direction) during the production of wetlaid nonwoven fabrics, and as a result, the fibers tend to be strongly bonded to each other in the production direction (warp direction) in extensible wetlaid nonwoven fabrics. Therefore, it is preferable that the tensile strength in the warp direction be in the above-mentioned range.

[0060] In addition, since tensile strength is often required in both the warp and weft directions, such as when forming an extensible wetlaid nonwoven fabric, the tensile strength in both the warp and weft directions is preferably 3 N / (50 mm width) or more, more preferably 5 N / (50 mm width) or more, even more preferably 10 N / (50 mm width) or more, even more preferably 20 N / (50 mm width) or more, and even more preferably 25 N / (50 mm width) or more.

[0061] This "tensile strength" is measured by taking a rectangular specimen 50 mm wide and 250 mm long from the extensible wet nonwoven fabric, pulling the rectangular specimen in the long direction using a constant-speed extension tensile tester (Tensilon, manufactured by Orientec Co., Ltd.), and measuring the maximum load applied until the specimen breaks. This maximum load is measured for three specimens, and the arithmetic average of these maximum loads is taken as the "tensile strength." The measurement is performed under conditions of a gripping distance of 200 mm and a pulling speed of 500 mm / min.

[0062] The extensible wetlaid nonwoven fabric of the present invention preferably has the above-mentioned tensile strength, and in order to facilitate the attainment of such tensile strength, it is preferable that the fibers constituting the extensible wetlaid nonwoven fabric are entangled with each other. This entanglement refers to entanglement caused by applying an external force (e.g., a fluid flow such as a water flow) to the wetlaid fiber web, in addition to the entanglement of fibers caused when the wetlaid fiber web is formed.

[0063] The basis weight of the stretchable wet-laid nonwoven fabric of the present invention varies depending on the intended use, and is not particularly limited, but is preferably 1 to 200 g / m 2 It is preferable that the thickness is 5 to 150 g / m 2More preferably, it is 10 to 100 g / m 2 In the present invention, the basis weight is determined by taking three test pieces of 10 cm square from the extensible wetlaid nonwoven fabric, measuring the mass of each test piece, and then calculating the arithmetic average of the masses of the three test pieces. 2 The value converted into the mass per unit area is called the basis weight.

[0064] The thickness of the extensible wetlaid nonwoven fabric of the present invention varies depending on the intended use and is not particularly limited, but is preferably 0.01 to 2.0 mm, more preferably 0.05 to 1.5 mm, even more preferably 0.1 to 1.0 mm, and even more preferably 0.1 to 0.8 mm. The "thickness" in the present invention is defined as the thickness per 5 cm2 of the main surface of the extensible wetlaid nonwoven fabric. 2 The thickness is measured at five randomly selected locations with a load of 0.98 N (=100 gf) per unit, and the arithmetic average of the thicknesses is calculated. Such thickness measurements can be performed, for example, with a high-precision digital length measuring instrument (Litematic (registered trademark), manufactured by Mitutoyo Corporation).

[0065] The air permeability of the extensible wetlaid nonwoven fabric of the present invention varies depending on the application and is not particularly limited. However, the air permeability indicates the degree of fiber dispersion to a certain extent. In other words, if the fiber dispersion is poor and the fabric is poorly textured, there are some areas that are easily permeable, and the air permeability tends to be high. Therefore, the air permeability is 300 cm 3 / cm 2 s or less, and 250 cm 3 / cm 2 s or less is more preferable, and 200 cm 3 / cm 2 s or less, and more preferably 150 cm 3 / cm 2On the other hand, if the breathability of the extensible wet-laid nonwoven fabric is too low, it means that the structure of the extensible wet-laid nonwoven fabric is too dense, which may result in problems such as air not being able to escape during molding, functional ingredients such as pastes and adhesives not being able to penetrate into the extensible wet-laid nonwoven fabric, and the anchor effect not being able to be expected. 3 / cm 2 ·s or more is preferable, and 20cm 3 / cm 2 s or more is preferable, and 30 cm 3 / cm 2 It is more preferable that the value is equal to or larger than ·s.

[0066] This air permeability (unit: cm 3 / cm 2 s) is measured in accordance with JIS L 1096:2010, 8.26.1 A method (Fragile type method). In other words, the measurement area is 38 cm 2 Under these conditions, the air flow rate is adjusted so that the pressure is 125 Pa, and the unit time and the air permeability per unit time are measured. Such measurements of air permeability can be performed, for example, using a Frazier-type air permeability tester (product number: FX3300) manufactured by TEXTESTAG.

[0067] The extensible wetlaid nonwoven fabric of the present invention is easy to stretch, has excellent adhesion to objects such as molds and human bodies, and is easy to handle, so that the tensile strength at 20% elongation in at least one direction is preferably 10 N / (5 cm width) or less, more preferably 8 N / (5 cm width) or less, even more preferably 6 N / (5 cm width) or less, and even more preferably 4 N / (5 cm width) or less. If the tensile strength at 20% elongation is too low, the shape stability tends to be poor, so it is preferably 0.1 N / (5 cm width) or more, more preferably 0.2 N / (5 cm width) or more, and even more preferably 0.5 N / (5 cm width) or more. As described above, the structure tends to be easily elongated in the horizontal direction, so the tensile strength at 20% elongation in the horizontal direction is preferably within the above range.

[0068] This tensile strength at 20% elongation is a value obtained by the following procedure. First, a sample piece with a width of 50 mm and a length of 250 mm is taken from the extensible wet nonwoven fabric. Next, using a constant-speed extension tensile tester (Tensilon, manufactured by Orientec Co., Ltd.), the sample piece is fixed with a gripping distance of 200 mm, and the load at the point of elongation of 40 mm (=20%) (grip distance: 240 mm) is measured. This load measurement is performed for three sample pieces, and the arithmetic average of these loads is taken as the "tensile strength at 20% elongation." The measurement is performed at a pulling speed of 500 mm / min.

[0069] Since the extensible wet nonwoven fabric of the present invention may require large extensibility, such as when it is deep-drawn or used as a base fabric for a patch to be applied to the elbow, knee, etc. of the human body, in such cases, in order to ensure excellent adhesion to the target object and excellent handling, the tensile strength at 50% elongation in at least one direction is preferably 15N / (5cm width) or less, more preferably 10N / (5cm width) or less, even more preferably 8N / (5cm width) or less, even more preferably 6N / (5cm width) or less, and even more preferably 4N / (5cm width) or less. If the tensile strength at 50% elongation is too low, the shape stability tends to be poor, so it is preferably 0.1N / (5cm width) or more, more preferably 0.2N / (5cm width) or more, and even more preferably 0.5N / (5cm width) or more. As described above, since the structure of the material has a tendency to be easily stretched in the transverse direction, it is preferable that the tensile strength at 50% elongation in the transverse direction is within the above range.

[0070] This tensile strength at 50% elongation is a value obtained by the following procedure. First, a sample piece with a width of 50 mm and a length of 250 mm is taken from the extensible wet nonwoven fabric. Next, using a constant-speed extension tensile tester (Tensilon, manufactured by Orientec Co., Ltd.), the sample piece is fixed with a gripping distance of 200 mm, and the load at the point of elongation of 100 mm (=50%) (grip distance: 300 mm) is measured. This load measurement is performed for three sample pieces, and the arithmetic average of these loads is taken as the "tensile strength at 50% elongation." The measurement is performed at a pulling speed of 500 mm / min.

[0071] The extensible wetlaid nonwoven fabric of the present invention has a recovery rate at 20% elongation in at least one direction of preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and even more preferably 50% or more so that it has excellent adhesion to objects such as molds and the human body by stretching. Note that, in order to have excellent adhesion to objects, the recovery rate at 20% elongation in both the warp and cross directions is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and even more preferably 50% or more.

[0072] This recovery rate at 20% elongation is a value obtained by the following procedure. First, a sample piece with a width of 50 mm and a length of 250 mm is taken from the extensible wet nonwoven fabric. Next, using a constant-speed extension tensile tester (Tensilon, manufactured by Orientec Co., Ltd.), the test piece is fixed with a gripping distance of 200 mm. The gripping distance of 200 mm is set as the starting point, and a position 40 mm from the starting point (= 20% elongation position, elongation L 20 The test pieces are pulled at a speed of 500 mm / min to a tension of 0.05 N (Lf = 40), and then returned to the starting point at the same speed. The elongation (Lf) when the tensile stress of the extensible wet-laid nonwoven fabric reaches 0.05 N during this pulling operation, and the elongation (Lb) when the tensile stress of the extensible wet-laid nonwoven fabric reaches 0.05 N during the return operation are measured. This measurement is carried out for three test pieces, and the elongations (Lf, Lb) are arithmetically averaged to obtain the average elongation (Lf) during the pulling operation. av ) and the average elongation during return operation (Lb av The value calculated from the following formula is the recovery rate at 20% elongation (R, unit: %). R = {(L 20 -Lf av )-(Lb av -Lf av )} / (L 20 -Lf av ) x 100

[0073] Since the extensible wet-laid nonwoven fabric of the present invention may require large extensibility, such as when it is deep-drawn or used as a base fabric for a patch to be applied to the elbow, knee, etc. of the human body, even in such cases, in order to ensure excellent adhesion to the target object and excellent handling, the recovery rate at 50% elongation in at least one direction is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and even more preferably 50% or more. Note that, in order to ensure excellent adhesion to the target object, the recovery rate at 50% elongation in both the vertical and horizontal directions is preferably 20% or more, and more preferably 30% or more.

[0074] This recovery rate at 50% elongation is a value obtained by the following procedure. First, a sample piece with a width of 50 mm and a length of 250 mm is taken from the extensible wet nonwoven fabric. Next, using a constant-speed extension tensile tester (Tensilon, manufactured by Orientec Co., Ltd.), the test piece is fixed with a gripping distance of 200 mm. The gripping distance of 200 mm is set as the starting point, and a position 100 mm from the starting point (= 50% elongation position, elongation L 50 The test pieces are pulled at a speed of 500 mm / min to a pulling position (Lf = 100) and then returned to the starting point at the same speed. The elongation (Lf) when the tensile stress of the extensible wet-laid nonwoven fabric reaches 0.05 N during this pulling operation, and the elongation (Lb) when the tensile stress of the extensible wet-laid nonwoven fabric reaches 0.05 N during the return operation are measured. This measurement is carried out for three test pieces, and the elongations (Lf, Lb) are arithmetically averaged to obtain the average elongation (Lf) during the pulling operation. av ) and the average elongation during return operation (Lb av The value calculated from the following formula is the "50% elongation recovery rate (R, unit: %)." R = {(L 50 -Lf av )-(Lb av -Lf av )} / (L 50 -Lf av ) x 100

[0075] The extensible wetlaid nonwoven fabric of the present invention is an extensible wetlaid nonwoven fabric that has small variation in dynamic friction coefficient and is wrinkle-free or inconspicuous in addition to extensibility, and therefore can be used in various applications where extensibility is preferred. For example, it can be used as a material for clothing (interlining, padding, base material for brassiere cups, shoulder pads, etc.), surface material for automobile ceiling materials, surface material for interior materials, FRP base material, printing base material, synthetic leather base material, adhesive tape base material, patch base material, and sanitary material base material (bandages, mask materials (sanitary masks, dust masks or their ear loops), diapers, sanitary products, etc.).

[0076] When the extensible wetlaid nonwoven fabric of the present invention has stretchability in addition to extensibility, it can be suitably used as a base material for a patch, for example, a cataplasm, a plaster, a tape preparation, a surgical tape, a taping material or a bandage, a facial mask, a warming sheet or a cooling sheet, etc., which retains a functional ingredient for the purpose of exerting an anti-inflammatory and analgesic effect, for the purpose of exerting a cosmetic effect by a cosmetic, or for the purpose of giving a warm or cool feeling.

[0077] In addition, the extensible wetlaid nonwoven fabric of the present invention can be laminated and integrated with other materials such as other nonwoven fabrics (e.g., spunbonded nonwoven fabrics, meltblown nonwoven fabrics, direct spun nonwoven fabrics such as electrospun nonwoven fabrics, dry nonwoven fabrics, and wetlaid nonwoven fabrics having an elongation rate of less than 30% in any direction), woven fabrics, knitted fabrics, porous films, and nets to suit various applications.

[0078] The extensible wetlaid nonwoven fabric of the present invention can be produced, for example, by using latent crimped fibers, apparent crimped fibers, adhesive fibers, fine fibers and / or regular fibers, forming a fiber web by a wet method, and then bonding the fibers together. In particular, when latent crimped fibers and / or apparent crimped fibers are used as the fibers constituting the extensible wetlaid nonwoven fabric, an extensible wetlaid nonwoven fabric having excellent stretchability can be produced, and when adhesive fibers are used as the fibers constituting the extensible wetlaid nonwoven fabric, an extensible wetlaid nonwoven fabric having excellent strength can be produced. In particular, when an extensible wetlaid nonwoven fabric is produced using both latent crimped fibers and adhesive fibers, the crimped fibers made of latent crimped fibers that have developed crimps mainly contribute to the effects of extensibility and stretchability, and the adhesive fibers contribute to the effect of improving strength, so that an extensible wetlaid nonwoven fabric having excellent stretchability and strength in addition to extensibility can be produced, which is preferable. In addition, it is preferable to produce an extensible wet-laid nonwoven fabric using both latent and apparent crimp fibers, since it is easy to produce an extensible wet-laid nonwoven fabric that is excellent in extensibility and stretchability and has no or inconspicuous wrinkles.Furthermore, it is preferable to produce an extensible wet-laid nonwoven fabric using latent crimp fibers, apparent crimp fibers, and adhesive fibers, since it is easy to produce an extensible wet-laid nonwoven fabric that is excellent in extensibility, stretchability, and strength and has no or inconspicuous wrinkles.

[0079] (Example 1) A latent crimped fiber is used, preferably an adhesive fiber is used in addition to the latent crimped fiber, and a wet fiber web containing the latent crimped fiber is formed by a wet method. Thereafter, the latent crimped fiber constituting the wet fiber web is caused to crimp to increase the bonding caused by the entanglement of the fibers, thereby producing the extensible wet nonwoven fabric of the present invention. When the latent crimped fiber constituting the wet fiber web is caused to crimp to increase the bonding caused by the entanglement of the fibers, the area of ​​the wet fiber web decreases with the occurrence of crimp. Conventionally, the area shrinkage rate was usually about 30 to 50%, but in the present invention, the crimp is caused to occur under conditions where the area shrinkage rate is 55% or more (preferably 60% or more), so that the crimp of the latent crimped fiber is sufficiently expressed, and the crimp radius is reduced, thereby making wrinkles less noticeable. In particular, after the latent crimped fibers are allowed to develop crimps, the fabric is pressed, preferably heated and pressed, to adjust the thickness, so that the variation in the dynamic friction coefficient is less than 0.04, making wrinkles less noticeable. This extensible wet nonwoven fabric contains crimped fibers made of latent crimped fibers that have developed crimps, and therefore has excellent stretchability. In addition, the area shrinkage is large and the fibers are strongly entangled, so that the recovery rate at 20% elongation and the recovery rate at 50% elongation can be increased, and the tensile strength at 20% elongation and 50% elongation can be reduced. In addition, since the area shrinkage increases, the basis weight and thickness increase, and therefore, in order to obtain an extensible wet nonwoven fabric with the desired basis weight and thickness, it is necessary to appropriately adjust the basis weight of the wet fiber web before shrinkage, for example by reducing it. This area shrinkage (Rs) is a value calculated from the following formula. Rs = [(Sb-Sa) / Sb] × 100 Here, Sb means the area of ​​the wet fiber web before shrinkage, and Sa means the area of ​​the wet fiber web after shrinkage.

[0080] In this specific example, it is preferable to use thin latent crimp fibers having a fiber diameter of 18 μm or less (preferably 15 μm or less, more preferably 12 μm or less, even more preferably 11 μm or less, even more preferably 10 μm or less, even more preferably 9 μm or less, and even more preferably 8 μm or less) as the latent crimp fibers, so that wrinkles are less noticeable and the fibers are more easily entangled.

[0081] As described above, when the adhesive fiber is included in addition to the latent crimp fiber and the adhesive fiber is bonded, the extensible wet nonwoven fabric has excellent strength and is easier to handle. When the adhesive fiber is included, the mass ratio of the latent crimp fiber to the adhesive fiber is preferably 99:1 to 50:50, more preferably 95:5 to 60:40, and even more preferably 90:10 to 70:30. The bonding with the adhesive fiber can be performed before, simultaneously with, or after the crimp of the latent crimp fiber is developed. However, tension is applied to the wet fiber web during transportation and when the crimp is developed, which tends to impair the uniform dispersion of the fibers. Therefore, it is preferable to bond the adhesive fiber to the wet fiber web before the crimp of the latent crimp fiber is developed to form a bonded wet fiber web.

[0082] In addition to the latent crimp fibers and adhesive fibers, the fabric may contain visibly crimped fibers, splittable fibers, fine fibers and / or regular fibers.

[0083] (Example 2) A wet-laid fiber web containing latent crimped fibers is formed by a wet method using latent crimped fibers, preferably using adhesive fibers in addition to the latent crimped fibers. Next, a fluid flow such as a water flow is applied to the wet-laid fiber web to entangle the fibers to form an entangled wet-laid fiber web. Thereafter, the crimp of the latent crimped fibers constituting the entangled wet-laid fiber web is expressed, and the extensible wet-laid nonwoven fabric of the present invention can be produced. In this production method, a fluid flow such as a water flow is applied to the wet-laid fiber web to form voids in the wet-laid fiber web in which the latent crimped fibers can express crimp, thereby preventing the occurrence of wrinkles. In other words, since a wetlaid fiber web has a uniform and dense structure, there are no voids in which the latent crimp fibers can express crimps. Therefore, if the crimps are forcibly expressed so as to have extensibility, the wetlaid fiber web tends to fold in its thickness direction due to the expression of crimps, and wrinkles tend to occur. However, in this specific example, by ensuring voids in which the latent crimp fibers can express crimps, the occurrence of wrinkles is prevented.

[0084] In order to form suitable voids in the wetlaid fiber web, for example, a support having a wire diameter of 0.2 mm or more can be used as a support for supporting the wetlaid fiber web when a fluid flow such as a water flow is applied to the wetlaid fiber web. The same effect can be obtained by treating with needle punching instead of the action of a fluid flow. Among these, the action of a fluid flow is preferred because it allows the production of an extensible wetlaid nonwoven fabric having a dense structure and excellent uniform fiber dispersion.

[0085] In this case as well, after the crimp is developed, the film is pressed, preferably heated and pressed, to adjust the thickness, thereby making wrinkles less noticeable to the extent that the variation in dynamic friction coefficient is less than 0.04.

[0086] This extensible wetlaid nonwoven fabric has excellent stretchability because it contains crimped fibers made of latent crimped fibers that have been crimped. In this specific example, it is preferable to use thin latent crimped fibers with a fiber diameter of 18 μm or less (preferably 15 μm or less, more preferably 12 μm or less, even more preferably 11 μm or less, even more preferably 10 μm or less, even more preferably 9 μm or less, and even more preferably 8 μm or less) as the latent crimped fibers so that wrinkles are less noticeable.

[0087] In addition to the latent crimped fibers, the adhesive fibers are included and the adhesive fibers are bonded to the wetlaid nonwoven fabric, which has excellent strength and is easier to handle. When the adhesive fibers are included, the mass ratio of the latent crimped fibers to the adhesive fibers is preferably 99:1 to 50:50, more preferably 95:5 to 60:40, and even more preferably 90:10 to 70:30. The bonding with the adhesive fibers can be performed before applying a fluid flow such as a water flow to the wetlaid fiber web, after forming the entangled wetlaid fiber web, simultaneously with the occurrence of crimp of the latent crimped fibers, or after the occurrence. In particular, when the adhesive fibers are bonded to the wetlaid fiber web before applying a fluid flow such as a water flow to the wetlaid fiber web, even if a fluid flow is applied to the wetlaid fiber web, appropriate voids can be formed without significantly disturbing the texture of the wetlaid fiber web, and as a result, it is preferable to easily produce a wrinkle-free extensible wetlaid nonwoven fabric.

[0088] In addition to the latent crimp fibers and adhesive fibers, the fabric may contain visibly crimped fibers, splittable fibers, fine fibers and / or regular fibers.

[0089] (Example 3) A wet-laid fiber web containing latent crimped fibers and apparent crimped fibers is formed by a wet method using latent crimped fibers and apparent crimped fibers, preferably by further using adhesive fibers. Next, a fluid flow such as a water flow is applied to the wet-laid fiber web to entangle the fibers to form an entangled wet-laid fiber web, or the wet-laid fiber web is used as it is to develop the crimp of the latent crimped fibers constituting the entangled wet-laid fiber web or the wet-laid fiber web, thereby producing the extensible wet-laid nonwoven fabric of the present invention. In this manufacturing method, the fibers constituting the entangled wet-laid fiber web or the wet-laid fiber web contain apparent crimped fibers, and the bulkiness of the apparent crimped fibers makes it easy to form voids in which the latent crimped fibers can develop crimps, thereby preventing the occurrence of wrinkles. In other words, since the entangled wetlaid fiber web or wetlaid fiber web has a uniform and dense structure, there are no voids in which the latent crimp fibers can express crimp, so if the crimp of the latent crimp fibers is forcibly expressed so as to have extensibility, the entangled wetlaid fiber web or wetlaid fiber web tends to fold in its thickness direction due to the expression of crimp, and wrinkles tend to occur. However, in this specific example, the presence of the visibly crimped fibers ensures voids in which the latent crimp fibers can express crimp, making it easy to prevent the occurrence of wrinkles.

[0090] Thus, in order to facilitate the formation of voids in the entangled wetlaid fiber web or wetlaid fiber web in which the latent crimped fiber can express crimps, the number of crimps of the visibly crimped fiber is preferably 3 / 25 mm or more, more preferably 4 / 25 mm or more, and even more preferably 5 / 25 mm or more. On the other hand, if the number of crimps is too high, the fibers are not uniformly dispersed in the entangled wetlaid fiber web or wetlaid fiber web, which tends to result in disturbance of the texture of the extensible wetlaid nonwoven fabric, so the number of crimps is preferably 16 / 25 mm or less, more preferably 13 / 25 mm or less, and even more preferably 11 / 25 mm or less. Also, if the crimp percentage of the visibly crimped fibers is too large, the fibers will not be uniformly dispersed in the entangled wetlaid fiber web or wetlaid fiber web, resulting in disturbance of the texture of the extensible wetlaid nonwoven fabric, so the crimp percentage is preferably 18% or less, more preferably 15% or less, and even more preferably 11% or less. On the other hand, in order to ensure voids in which the latently crimped fibers can express crimp and to facilitate the production of an extensible wetlaid nonwoven fabric with inconspicuous wrinkles, the crimp percentage is preferably 4% or more, more preferably 5% or more, and even more preferably 7% or more. The crimp number of this apparent crimp fiber is a value measured in accordance with JIS 1015:2010 "Test method for synthetic fiber staples" 8.12.1 (number of crimps) with a gripping distance of 1 / 2 the fiber length, and the crimp rate is a value measured in accordance with the "shrink rate" specified in JIS standard 8.12.2 (shrink rate and residual shrink rate).

[0091] In order to form suitable voids in the wetlaid fiber web, the visibly crimped fibers are preferably contained in the entangled wetlaid fiber web or wetlaid fiber web at 20 mass% or more, more preferably 30 mass% or more, and even more preferably 40 mass% or more. On the other hand, since the latently crimped fibers are contained, the visibly crimped fibers are preferably contained in the entangled wetlaid fiber web or wetlaid fiber web at 80 mass% or less, more preferably 70 mass% or less, and even more preferably 60 mass% or less. In addition, although the latent crimp fibers and / or adhesive fibers may have crimps, when the latent crimp fibers and / or adhesive fibers have crimps, they are regarded as visibly crimped fibers, and it is preferable that the total amount of the visibly crimped fibers that are also visibly crimped fibers or adhesive fibers and the visibly crimped fibers that are neither visibly crimped fibers nor adhesive fibers satisfies the above-mentioned mass ratio.

[0092] In this case as well, after the crimp is developed, the film is pressed, preferably heated and pressed, to adjust the thickness, thereby making wrinkles less noticeable to the extent that the variation in dynamic friction coefficient is less than 0.04.

[0093] This extensible wetlaid nonwoven fabric has excellent stretchability because it contains crimped fibers made of latent crimped fibers that have been crimped and manifested crimped fibers. In this specific example, it is preferable to use thin latent crimped fibers with a fiber diameter of 18 μm or less (preferably 15 μm or less, more preferably 12 μm or less, even more preferably 11 μm or less, even more preferably 10 μm or less, even more preferably 9 μm or less, even more preferably 8 μm or less) so that wrinkles are less noticeable. On the other hand, the fiber diameter of the manifested crimp fiber is preferably 1 μm or more (more preferably 5 μm or more, and even more preferably 10 μm or more) so that the latent crimp fiber can easily form voids in which it can express crimp. If the fiber diameter of the manifested crimp fiber is too large, it tends to disrupt the texture of the extensible wetlaid nonwoven fabric, so the fiber diameter is preferably 100 μm or less (more preferably 50 μm or less, even more preferably 30 μm or less, and even more preferably 20 μm or less).

[0094] In addition to the latent crimp fiber and the apparent crimp fiber, the adhesive fiber is also included, and the extensible wet nonwoven fabric is excellent in strength and easier to handle when the adhesive fiber is attached. When the adhesive fiber is also included, the mass ratio of the latent crimp fiber, the apparent crimp fiber, and the adhesive fiber is preferably 10-70:20-80:10-70, more preferably 20-70:20-70:10-60, and even more preferably 30-70:20-60:10-50. The adhesive fiber can have crimp, but even if the adhesive fiber has crimp, it is preferable that the amount of the adhesive fiber satisfies the above mass ratio.

[0095] The bonding with the adhesive fiber can be performed before applying a fluid flow such as a water flow to the wetlaid fiber web (i.e., to the wetlaid fiber web), after forming the entangled wetlaid fiber web, or simultaneously with or after the crimp of the latent crimp fiber is expressed. When applying a fluid flow such as a water flow to the wetlaid fiber web, it is preferable to bond with the adhesive fiber before applying a fluid flow such as a water flow to the wetlaid fiber web, because even if a fluid flow is applied to the wetlaid fiber web, the texture of the wetlaid fiber web is not significantly disturbed and a wrinkle-free extensible wetlaid nonwoven fabric can be easily produced.

[0096] The extensible wetlaid nonwoven fabric may contain splittable fibers, fine fibers and / or regular fibers in addition to the latent crimp fibers, apparent crimp fibers and adhesive fibers.

[0097] The specific examples described above are suitable methods for producing the extensible wetlaid nonwoven fabric of the present invention, but in order to add value to the extensible wetlaid nonwoven fabric, post-processing such as coloring treatment such as dyeing; embossing treatment; printing treatment such as printing; and surface treatment such as plasma treatment and water-repellent treatment can be carried out.

[0098] In addition, when the extensible wetlaid nonwoven fabric of the present invention is laminated and integrated with other materials such as other nonwoven fabrics (e.g., direct spun nonwoven fabrics such as spunbonded nonwoven fabrics, meltblown nonwoven fabrics, electrospun nonwoven fabrics, dry nonwoven fabrics, wet nonwoven fabrics with an elongation rate in any direction of less than 30%), woven fabrics, knitted fabrics, porous films, nets, etc., the extensible wetlaid nonwoven fabric can be laminated and integrated with other materials to produce the fabric. For example, the extensible wetlaid nonwoven fabric can be integrated with other materials by a fluid flow such as a water flow, a needle, fiber adhesion and / or a binder. The extensible wetlaid nonwoven fabric may be integrated with other materials after it is formed, or may be integrated with other materials at the stage of producing the extensible wetlaid nonwoven fabric. For example, by laminating a wetlaid fiber web on other materials and then applying a fluid flow, the extensible wetlaid nonwoven fabric can be integrated with other materials at the same time as the extensible wetlaid nonwoven fabric is formed. The other materials are preferably materials that do not inhibit the extensibility of the extensible wetlaid nonwoven fabric of the present invention, and therefore, the other materials also preferably have an extensibility of 30% or more in at least one direction. EXAMPLES

[0099] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0100] Example 1 A side-by-side type latent crimp fiber (fiber diameter: 10.1 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0101] Additionally, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 3 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) with a core component of polyester (melting point: 250°C) and a sheath component of copolymer polyester (melting point: 110°C).

[0102] Next, a slurry was formed in which side-by-side type latent crimped fibers and core-sheath type adhesive fibers were dispersed in a mass ratio of 90:10. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 30 g / m 2 ) was formed.

[0103] Next, while the bonded wet-laid fiber web was being transported on a conveyor with a wire diameter of 0.2 mm at a speed of 5 m / min, a shower was applied to one side of the bonded wet-laid fiber web using a single-row nozzle (diameter: 0.13 mm, pitch: 0.6 mm), and then water was sprayed at a pressure of 3 MPa onto the showered surface and then at a pressure of 3 MPa onto the opposite surface of the showered surface to perform hydroentanglement, thereby forming a hydroentangled fiber web.

[0104] Next, the hydroentangled fiber web was dried and then heat-treated at 160°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the hydroentangled fiber web (area shrinkage rate: 47%) and re-adhering the adhesive fibers to produce a wet-laid nonwoven fabric (basis weight: 57 g / m2) containing the crimped fibers made of the latent crimped fibers that had developed crimps and the adhered core-sheath type adhesive fibers. 2 , average fiber diameter: 10.1 μm) was produced.

[0105] The wet-laid nonwoven fabric was then heated and pressurized at a temperature of 100° C. and a pressure of 0.3 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.40 mm.

[0106] Example 2 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0107] Additionally, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 3 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) with a core component of polyester (melting point: 250°C) and a sheath component of copolymer polyester (melting point: 110°C).

[0108] Next, a slurry was formed in which side-by-side type latent crimped fibers and core-sheath type adhesive fibers were dispersed in a mass ratio of 80:20. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 30 g / m 2 ) was formed.

[0109] Next, while the wet-bonded fiber web was being transported on a conveyor with a wire diameter of 0.2 mm at a speed of 5 m / min, a shower was applied to one side of the bonded wet-laid fiber web using a single-row nozzle (diameter: 0.13 mm, pitch: 0.6 mm), and then water was sprayed at a pressure of 3 MPa onto the showered surface and then at a pressure of 3 MPa onto the opposite surface of the showered surface to perform hydroentanglement, thereby forming a hydroentangled fiber web.

[0110] Next, the hydroentangled fiber web was dried and then heat-treated at 170°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the hydroentangled fiber web (area shrinkage rate: 54%) and re-adhering the adhesive fibers to produce a wetlaid nonwoven fabric (basis weight: 65 g / m2) containing the crimped fibers made of the latent crimped fibers that developed crimps and the bonded core-sheath type adhesive fibers. 2 , average fiber diameter: 10.8 μm) was produced.

[0111] The wet-laid nonwoven fabric was then heated and pressurized at a temperature of 100° C. and a pressure of 0.3 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.26 mm.

[0112] Example 3 A side-by-side type latent crimp fiber (fiber diameter: 14.3 μm, fiber length: 15 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0113] Next, a slurry in which only the side-by-side type latent crimped fibers are dispersed is formed, and the slurry is drawn up and then dried at a temperature of 100°C to obtain a wet-laid fiber web (basis weight: 30 g / m 2 ) was formed.

[0114] Next, while the wet fiber web was being transported on a conveyor with a line diameter of 0.4 mm at a speed of 5 m / min, a shower was applied to one side of the wet fiber web using a single row nozzle (diameter: 0.13 mm, pitch: 0.6 mm), and then water was sprayed at a pressure of 3 MPa onto the showered side and then at a pressure of 3 MPa onto the opposite side of the showered side to perform hydroentanglement, thereby forming a hydroentangled fiber web.

[0115] Next, the hydroentangled fiber web was dried and then heat-treated at 160°C using a hot air dryer to induce crimping of the latent crimped fibers, thereby shrinking the hydroentangled fiber web (area shrinkage rate: 46%) and producing a wet-laid nonwoven fabric (basis weight: 55 g / m2) consisting only of the crimped fibers that had expressed the crimping. 2 , average fiber diameter: 14.3 μm) was produced.

[0116] The wet-laid nonwoven fabric was then heated and pressed at a temperature of 130° C. and a pressure of 0.4 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.20 mm.

[0117] Example 4 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0118] Next, a slurry in which only the side-by-side type latent crimped fibers are dispersed is formed, and the slurry is drawn up and then dried at a temperature of 100°C to obtain a wet-laid fiber web (basis weight: 20 g / m 2 ) was formed.

[0119] Next, while the wet fiber web was being transported on a conveyor with a wire diameter of 0.2 mm at a speed of 5 m / min, a shower was applied to one side of the wet fiber web using a single row nozzle (diameter: 0.13 mm, pitch: 0.6 mm), and then water was sprayed at a pressure of 3 MPa onto the showered side and then at a pressure of 3 MPa onto the opposite side of the showered side to perform hydroentanglement, thereby forming a hydroentangled fiber web.

[0120] Next, the hydroentangled fiber web was dried and then heat-treated at 165°C using a hot air dryer to induce crimping of the latent crimped fibers, thereby shrinking the hydroentangled fiber web (area shrinkage rate: 63%) and producing a wet-laid nonwoven fabric (basis weight: 54 g / m2) consisting only of the crimped fibers that had expressed the crimping. 2 , average fiber diameter: 11.0 μm) was produced.

[0121] The wet-laid nonwoven fabric was then heated and pressurized at a temperature of 100° C. and a pressure of 0.3 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.53 mm.

[0122] Example 5 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0123] In addition, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 5 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%), with polyester (melting point: 250°C) as the core component and copolymer polyester (melting point: 110°C) as the sheath component.

[0124] Next, a slurry was formed in which side-by-side type latent crimped fibers and core-sheath type adhesive fibers were dispersed in a mass ratio of 80:20. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 20 g / m 2 ) was formed.

[0125] Next, the bonded wet fiber web is dried and then heat-treated at a temperature of 160°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 63%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 54 g / m2) containing crimped fibers made of the latent crimped fibers that have developed crimps and core-sheath type bonded fibers. 2 , average fiber diameter: 10.8 μm) was produced.

[0126] The wet-laid nonwoven fabric was then heated and pressurized at a temperature of 100° C. and a pressure of 0.3 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.40 mm.

[0127] Example 6 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0128] In addition, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 5 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%), with polyester (melting point: 250°C) as the core component and copolymer polyester (melting point: 110°C) as the sheath component.

[0129] Next, a slurry was formed in which side-by-side type latent crimped fibers and core-sheath type adhesive fibers were dispersed in a mass ratio of 80:20. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 17 g / m 2 ) was formed.

[0130] Next, the bonded wet fiber web is dried and then heat-treated at a temperature of 175°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 72%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 61 g / m2) containing crimped fibers made of the latent crimped fibers that have developed crimps and core-sheath type bonded fibers. 2 , average fiber diameter: 10.8 μm) was produced.

[0131] The wet-laid nonwoven fabric was then heated and pressurized at a temperature of 100° C. and a pressure of 0.3 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.60 mm.

[0132] Example 7 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0133] In addition, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 5 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%), with polyester (melting point: 250°C) as the core component and copolymer polyester (melting point: 110°C) as the sheath component.

[0134] Next, a slurry was formed in which side-by-side type latent crimped fibers and core-sheath type adhesive fibers were dispersed in a mass ratio of 80:20. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 17 g / m 2 ) was formed.

[0135] Next, the bonded wet fiber web is dried, and then heat-treated at a temperature of 180°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 81%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 87 g / m2) containing crimped fibers made of the latent crimped fibers that have developed crimps and core-sheath type bonded fibers. 2 , average fiber diameter: 10.8 μm) was produced.

[0136] The wet-laid nonwoven fabric was then heated and pressed at a temperature of 100° C. and a pressure of 0.4 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.41 mm.

[0137] Comparative Example 1 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0138] In addition, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 5 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%), with polyester (melting point: 250°C) as the core component and copolymer polyester (melting point: 110°C) as the sheath component.

[0139] Next, a slurry was formed in which side-by-side type latent crimped fibers and core-sheath type adhesive fibers were dispersed in a mass ratio of 80:20. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 34 g / m 2 ) was formed.

[0140] Next, the bonded wet fiber web is dried and then heat-treated at a temperature of 155°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 33%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 51 g / m2) containing crimped fibers made of the latent crimped fibers that have developed crimps and core-sheath type bonded fibers. 2 , average fiber diameter: 10.8 μm) was produced.

[0141] The wet-laid nonwoven fabric was then heated and pressed at a temperature of 100° C. and a pressure of 0.3 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.49 mm.

[0142] Comparative Example 2 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0143] In addition, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 5 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%), with polyester (melting point: 250°C) as the core component and copolymer polyester (melting point: 110°C) as the sheath component.

[0144] Next, a slurry was formed in which side-by-side type latent crimped fibers and core-sheath type adhesive fibers were dispersed in a mass ratio of 80:20. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 21 g / m 2 ) was formed.

[0145] Next, the bonded wet fiber web was dried and then heat-treated at a temperature of 165°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 52%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 44 g / m2) containing crimped fibers made of the latent crimped fibers that have developed crimps and core-sheath type bonded fibers. 2 , average fiber diameter: 10.8 μm) was produced.

[0146] The wet-laid nonwoven fabric was then heated and pressurized at a temperature of 100° C. and a pressure of 0.3 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.41 mm.

[0147] Example 8 A side-by-side type latent crimp fiber (fiber diameter: 11.0 μm, fiber length: 10 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%) was prepared, which was a combination of polyester (melting point: 250°C) and copolymer polyester (melting point: 230°C).

[0148] In addition, we prepared a core-sheath adhesive fiber (fiber diameter: 10.1 μm, fiber length: 5 mm, white, cross-sectional shape: circular, number of crimps: 0 / 25 mm, crimp rate: 0%), with polyester (melting point: 250°C) as the core component and copolymer polyester (melting point: 110°C) as the sheath component.

[0149] Furthermore, a visibly crimped fiber (fiber diameter: 14.3 μm, fiber length: 10 mm, white, cross-sectional shape: triangular, number of crimps: 8.0 / 25 mm, crimp rate: 9.0%) made of polyester (melting point: 250° C.) was prepared.

[0150] Next, a slurry was formed in which side-by-side type latent crimped fibers, core-sheath type adhesive fibers, and apparent crimped fibers were dispersed in a mass ratio of 70:10:20. The slurry was then drawn up and heat-treated at a temperature of 110°C to bond the fibers together by the adhesion of the sheath component of the core-sheath type adhesive fibers, producing an adhesive wet fiber web (basis weight: 20 g / m 2 ) was formed.

[0151] Next, the bonded wet fiber web is dried and then heat-treated at a temperature of 145°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 49%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 39 g / m2) containing crimped fibers made of latent crimped fibers that have developed crimps, apparent crimped fibers, and core-sheath type bonded fibers. 2 , average fiber diameter: 11.6 μm) was produced.

[0152] The wet-laid nonwoven fabric was then heated and pressed at a temperature of 40° C. and a pressure of 5.4 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.32 mm.

[0153] Example 9 A bonded wet fiber web (basis weight: 20 g / m) bonded with the core-sheath type bonded fibers was prepared in the same manner as in Example 8, except that a slurry was formed in which the side-by-side type latent crimped fibers, the core-sheath type bonded fibers, and the apparent crimped fibers were dispersed in a mass ratio of 60:10:30. 2 ) was formed.

[0154] Next, the bonded wet fiber web is dried and then heat-treated at a temperature of 148°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 53%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 43 g / m2) containing crimped fibers made of latent crimped fibers that have developed crimps, apparent crimped fibers, and core-sheath type bonded fibers. 2 , average fiber diameter: 11.9 μm) was produced.

[0155] The wet-laid nonwoven fabric was then heated and pressurized at a temperature of 40° C. and a pressure of 5.4 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.34 mm.

[0156] Comparative Example 3 A bonded wet fiber web (basis weight: 20 g / m) to which the core-sheath type bonded fibers were bonded was prepared in the same manner as in Example 8, except that a slurry in which the side-by-side type latent crimped fibers, the core-sheath type bonded fibers, and the apparent crimped fibers were dispersed in a mass ratio of 80:10:10 was formed. 2 ) was formed.

[0157] Next, the bonded wet fiber web is dried and then heat-treated at a temperature of 141°C using a hot air dryer to cause the latent crimped fibers to develop crimps, thereby shrinking the bonded wet fiber web (area shrinkage rate: 49%) and re-bonding the bonded fibers to produce a wet nonwoven fabric (basis weight: 39 g / m2) containing crimped fibers made of the latent crimped fibers that have developed crimps, apparent crimped fibers, and core-sheath type bonded fibers. 2 , average fiber diameter: 11.2 μm) was produced.

[0158] The wet-laid nonwoven fabric was then heated and pressed at a temperature of 40° C. and a pressure of 5.4 MPa to adjust the thickness, producing an extensible wet-laid nonwoven fabric having a thickness of 0.29 mm.

[0159] (Evaluation of stretchable wet nonwoven fabrics) The extensible wetlaid nonwoven fabrics of Examples 1 to 9 and Comparative Examples 1 to 3 were evaluated for basis weight, thickness, dynamic friction coefficient, variation in dynamic friction coefficient, tensile strength, elongation, tensile strength at 20% elongation, tensile strength at 50% elongation, recovery rate at 20% elongation, recovery rate at 50% elongation, and air permeability by the above-mentioned methods. The presence or absence of wrinkles in each extensible wetlaid nonwoven fabric was also visually evaluated. Photographs of one main surface of each of the extensible wetlaid nonwoven fabrics of Examples 1 to 9 and Comparative Examples 1 to 3 taken with a digital camera are shown in Figures 1 to 12 in order. The evaluation results of these extensible wetlaid nonwoven fabrics are as shown in Tables 1 and 2.

[0160] [Table 1]

[0161] [Table 2]

[0162] It can be seen from Tables 1 and 2 and Figs. 1 to 12 that the extensible wetlaid nonwoven fabrics of Examples 1 to 9, which have a variation in dynamic friction coefficient of less than 0.04, are extensible wetlaid nonwoven fabrics with excellent appearance quality, with no or inconspicuous wrinkles.

[0163] In addition, the extensible wetlaid nonwoven fabrics of Examples 1 to 9 of the present invention had no or inconspicuous wrinkles, and therefore had excellent abrasion resistance, and it was easy to predict that the fabrics would be able to fully exhibit their performance (e.g., water repellency) when post-processed. In addition, the fabrics had a pleasant feel to the touch. In particular, the extensible wetlaid nonwoven fabrics of Examples 1 to 3 and 5 to 7 had a tensile strength of 10 N / 50 mm or more in the machine direction, and were easy to handle.

[0164] Furthermore, as can be seen from Examples 1 to 4, by applying a water flow to the bonded wetlaid fiber web to form appropriate gaps in the bonded wetlaid fiber web and then fully expressing the crimp of the latent crimped fibers, it is possible to produce an extensible wetlaid nonwoven fabric with a variation in dynamic friction coefficient of less than 0.04 and no or inconspicuous wrinkles.

[0165] Furthermore, as can be seen from Examples 5 to 7 and Comparative Examples 1 to 3, it was found that by setting the areal shrinkage rate of the wetlaid fiber web to 55% or more, which is higher than conventional, it is possible to produce an extensible wetlaid nonwoven fabric with a kinetic friction coefficient variation of less than 0.04 and no or inconspicuous wrinkles, even without the application of a fluid flow such as a water flow.

[0166] Furthermore, as can be seen from Examples 8 to 9 and Comparative Example 3, it was found that, even without the application of a fluid flow such as a water flow, when the wetlaid fiber web contains 20 mass% or more of visibly crimped fibers, it is possible to produce an extensible wetlaid nonwoven fabric with a variation in dynamic friction coefficient of less than 0.04 and no or inconspicuous wrinkles. [Industrial Applicability]

[0167] The extensible wetlaid nonwoven fabric of the present invention is an extensible wetlaid nonwoven fabric that has small variation in dynamic friction coefficient and is wrinkle-free or inconspicuous in addition to extensibility, and therefore can be used in various applications where extensibility is preferred. For example, it can be used as a material for clothing (interlining, padding, base material for brassiere cups, shoulder pads, etc.), surface material for automobile ceiling materials, surface material for interior materials, FRP base material, printing base material, synthetic leather base material, adhesive tape base material, patch base material, and sanitary material base material (bandages, mask materials (sanitary masks, dust masks or their ear loops), diapers, sanitary products, etc.).

[0168] When the extensible wetlaid nonwoven fabric of the present invention has stretchability in addition to extensibility, it can be suitably used as a base material for a patch, for example, a cataplasm, a plaster, a tape preparation, a surgical tape, a taping material or a bandage, a facial mask, a warming sheet or a cooling sheet, etc., which retains a functional ingredient for the purpose of exerting an anti-inflammatory and analgesic effect, for the purpose of exerting a cosmetic effect by a cosmetic, or for the purpose of giving a warm or cool feeling.

Claims

1. An extensible wetlaid nonwoven fabric having an elongation rate of 30% or more in at least one direction, characterized in that the variation in the dynamic friction coefficient on at least one main surface of the extensible wetlaid nonwoven fabric is less than 0.04, and the fibers constituting the extensible wetlaid nonwoven fabric include crimped fibers.

2. An extensible wet nonwoven fabric having an elongation rate of 30% or more in at least one direction, wherein the variation in the dynamic friction coefficient on at least one of the main surfaces of the extensible wet nonwoven fabric is less than 0.04, and the fibers constituting the extensible wet nonwoven fabric contain latent crimp fibers that have expressed crimp.

3. An extensible wet nonwoven fabric having an elongation rate of 30% or more in at least one direction, wherein the variation in the dynamic friction coefficient on at least one of the main surfaces of the extensible wet nonwoven fabric is less than 0.04, and the fibers constituting the extensible wet nonwoven fabric include adhesive fibers.

4. An extensible wet nonwoven fabric having an elongation rate of 30% or more in at least one direction, wherein the variation in the dynamic friction coefficient on at least one of the main surfaces of the extensible wet nonwoven fabric is less than 0.04, and the fibers constituting the extensible wet nonwoven fabric include crimped fibers and adhesive fibers.

5. An extensible wet nonwoven fabric having an elongation rate of 30% or more in at least one direction, wherein the variation in the dynamic friction coefficient on at least one of the main surfaces of the extensible wet nonwoven fabric is less than 0.04, and the fibers constituting the extensible wet nonwoven fabric include latent crimped fibers that have expressed crimp and adhesive fibers.

6. An extensible wet nonwoven fabric described in any one of claims 1 to 5, characterized in that the tensile strength in at least one direction is 3 N / (50 mm width) or more.

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