Nonwoven fabric and production process thereof, liquid-containing sheet and wiping sheet

Abstract

[Problem] To provide a nonwoven fabric and a method for manufacturing the same, as well as a liquid-impregnated sheet and a wiping sheet. [Solution] The aforementioned nonwoven fabric (10) is a nonwoven fabric containing cellulose fibers (13), adhesive core-sheath type composite fibers (11), and non-adhesive core-sheath type composite fibers (14); relative to the total mass of the aforementioned nonwoven fabric, the content of the aforementioned adhesive core-sheath type composite fibers is 5% by mass or more and 20% by mass or less, and the content of the aforementioned cellulose fibers is 45% by mass or more and less than 90% by mass; and the aforementioned adhesive core-sheath type composite fibers have adhesive portions bonded at their intersection points, and the sheath portion of the aforementioned non-adhesive core-sheath type composite fibers contains an ethylene-vinyl alcohol copolymer.

Description

Technical Field

[0001] This invention relates to a nonwoven fabric, a liquid-impregnated sheet, and a wiping sheet.

[0002] This application claims priority to Japanese Patent Application No. 2020-53332, filed on March 24, 2020, which is incorporated herein by reference in its entirety. Prior Technology

[0003] In recent years, based on the ease of use, liquid-containing sheets made by impregnating non-woven fabrics with liquid have been used as liquid-containing sheets in face masks, coating sheets, wipes, etc.

[0004] Patent document 1 (Japanese Patent Application Publication No. 2008-261067) discloses a nonwoven sheet characterized by being formed by interlacing solvent-spun cellulose fibers with fiber lengths of 30-60 mm with core-sheath type composite fibers. The core-sheath type composite fibers consist of a sheath and a core, the sheath being an ethylene-vinyl alcohol copolymer and the core being a hydrophobic resin with a diameter of 5 μm-15 μm. According to this document, the solvent-spun cellulose fibers and the core-sheath type composite fibers are uniformly mixed and interlaced by water flow to form a nonwoven fabric, thereby providing a soft and fluffy fiber interlacing.

[0005] Patent document 2 (International Patent Publication No. 2015 / 046301) disclosed a liquid-retaining sheet made of nonwoven fabric containing 50% by mass or more of highly elastic fibers with a Young's modulus of 30 cN / T or more. According to this document, a liquid-retaining sheet and face mask can be provided that, even when pressed with a finger, the liquid component is rapidly returned to the sheet when it contains liquid components such as beauty essence (cosmetics). [Previous Technical Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2008-261067 [Patent Document 2] International Patent Publication No. 2015 / 046301 Summary of the Invention

[0007] [The problem the invention aims to solve] However, according to Patent Documents 1 and 2, the morphological stability is poor when using nonwoven fabric, so there is room for improvement.

[0008] Therefore, the object of the present invention is to provide a nonwoven fabric with excellent morphological stability, as well as a liquid impregnation sheet and a wiping sheet using the nonwoven fabric.

[0009] Another object of the present invention is to provide a nonwoven fabric with excellent morphological stability and good water retention and liquid release rates, as well as liquid impregnation sheets and wiping sheets using the nonwoven fabric.

[0010] Another objective of this invention is to provide a nonwoven fabric that, while exhibiting excellent operability due to its non-slippage between itself when folded, also exhibits low friction with the skin, thus reducing skin burden, as well as a liquid-impregnated sheet and a wiping sheet using the nonwoven fabric. [Technical means to solve the problem]

[0011] The inventors of this invention conducted intensive research in order to achieve the above-mentioned objective, and as a result, they discovered that, based on the viewpoint of improving morphological stability, if the core-sheath type composite fibers are used in a specific ratio and a bonding portion is formed at the intersection of the core-sheath type composite fibers, a pseudo-mesh state can be formed, thereby improving the overall morphological stability of the nonwoven fabric.

[0012] On the other hand, due to the improved morphological stability of the core-sheath type composite fiber, a new problem has been discovered: when the nonwoven fabric is compressed to a certain extent when applied to the skin, it may not provide sufficient liquid release, and the reduced space for liquid retention in the nonwoven fabric may lead to a decrease in water retention rate. Therefore, it is necessary to improve other fibers. Thus, the inventors have conducted in-depth research on this new problem and found that, when forming a pseudo-mesh state, the liquid release rate and water retention rate can be controlled by making the nonwoven fabric contain cellulose fibers and, as a third component, ethylene-vinyl alcohol copolymer (EVOH) in the sheath, and by setting the ratio of the aforementioned cellulose fibers within a specific range. This led to the completion of the present invention.

[0013] Specifically, the present invention may be configured in the following manner. [State 1] A nonwoven fabric comprising cellulose fibers, bonded core-sheath type composite fibers, and non-bonded core-sheath type composite fibers, characterized in that: Compared to the total mass of the aforementioned nonwoven fabric, the content of the aforementioned core-sheath type composite fiber is 5% by mass or more and 20% by mass or less (preferably 7% by mass or more and 17% by mass or less, more preferably 8% by mass or more and 15% by mass or less). The aforementioned cellulose fiber content is 45% by mass or more and less than 90% by mass (preferably 50% by mass or more and less than 90% by mass, more preferably 55% by mass or more and less than 88% by mass, and particularly 65% ​​by mass or more and less than 85% by mass); and The aforementioned core-sheath type composite fibers have an adhesive portion that bonds at the intersection points where they intersect. The aforementioned non-bonded core-sheath type composite fiber contains an ethylene-vinyl alcohol copolymer in its sheath portion. [State 2] The nonwoven fabric described in Sample 1 has a mass ratio of cellulose fiber content (T) to non-bonded core-sheath type composite fiber content (N) of T / N = 99 / 1~51 / 49 (preferably 95 / 5~55 / 45, more preferably 95 / 5~65 / 35, and even more preferably 95 / 5~75 / 25). [Style 3] The nonwoven fabric described in Sample 1 or Sample 2 has an elongation of 40% or less when absorbing saturated water (preferably 35% or less, more preferably 31% or less). [State 4] The nonwoven fabric described in any one of the samples 1 to 3, wherein the compressive hardness at 30% compression deformation after impregnation with a mixture of distilled water and glycerin (distilled water / glycerin mass ratio = 5 / 4) at 500% by mass of the nonwoven fabric and leaving it for 24 hours is 0.750~1.500 N / mm (preferably 0.800~1.400 N / mm, more preferably 0.850~1.300 N / mm). [Style 5] The nonwoven fabric described in any one of the samples 1 to 4, wherein the liquid release rate during 10 seconds when the nonwoven fabric is impregnated with a mixture of distilled water and glycerin (distilled water / glycerin mass ratio = 5 / 4) at 500% by mass and left for 24 hours and then compressed to 30% is 7 to 14% (preferably 8 to 12%). [Style 6] The nonwoven fabric described in any of the 1 to 5 samples has a water retention rate of 1145% or higher (preferably 1180% or higher, more preferably 1200% or higher). [State 7] The nonwoven fabric described in any of the states 1 to 6 has a static friction coefficient (A) between the nonwoven fabrics containing 400% by mass of distilled water and the difference (AC) between the static friction coefficient (C) of the nonwoven fabric containing 400% by mass of distilled water and the bioskin, which is 0.0170 to 0.1000 (preferably 0.0200 to 0.0900, more preferably 0.0300 to 0.0800). [Style 8] The nonwoven fabric described in any of the states 1 to 7, wherein the static friction coefficient (A) of the nonwoven fabric containing 400% by mass of distilled water is 0.0550 to 0.0900 (preferably 0.0600 to 0.0900, more preferably 0.0650 to 0.0880). [Style 9] The nonwoven fabric described in any of the samples 1 to 8, wherein the nonwoven fabric containing 400% by mass of distilled water has a static friction coefficient (C) of 0.0450 or less (preferably 0.0430 or less) with bioskin. [Style 10] The nonwoven fabric described in any of the 1 to 9 samples has a pile length of less than 10 times the average thickness (1 time) of the thickness (preferably less than 8 times, more preferably less than 5 times). [Style 11] A liquid-impregnated sheet is formed using the nonwoven fabric described in any one of the samples 1 to 10. [Style 12] A wiping sheet is formed using the nonwoven fabric described in any one of the states 1 to 10. [Style 13] A method for manufacturing a nonwoven fabric, which is the method for manufacturing a nonwoven fabric according to any one of the samples 1 to 10, comprising at least: A process for forming a strip with a cross-linked structure by interlocking a strip containing cellulose fibers, adhesive core-sheath type composite fibers, and non-adhesive core-sheath type composite fibers, wherein, relative to the total mass of the strip, the content of the aforementioned adhesive core-sheath type composite fibers is 5% by mass or more and 20% by mass or less, and the content of the aforementioned cellulose fibers is 45% by mass or more and less than 90% by mass; and In a strip with the aforementioned interlocking structure, a process is used to form an adhesive portion between the aforementioned non-adhesive core-sheath type composite fibers and an adhesive portion between the aforementioned adhesive core-sheath type composite fibers. [Style 14] The nonwoven fabric manufacturing method described in Sample 13, wherein the aforementioned interlocking process is water interlocking. [Style 15] The nonwoven fabric manufacturing method as described in Sample 13 or Sample 14, wherein, in the process of forming the aforementioned adhesive portion, heat treatment is performed at a temperature that is lower than the melting point of the sheath portion of the non-adhesive core-sheath type composite fiber and higher than the melting point of the sheath portion of the adhesive core-sheath type composite fiber.

[0014] Furthermore, any combination of at least two constituent elements disclosed in the claims and / or specification and / or drawings is included within the scope of this invention. In particular, any combination of two or more claims described in the claims is included within the scope of this invention. [Effects of the Invention]

[0015] According to the present invention, a nonwoven fabric with excellent morphological stability, water retention and liquid release properties can be provided. In particular, a nonwoven fabric with excellent operability, which does not easily slip between the nonwoven fabrics when folded and used, and has low friction with the skin, thus reducing the burden on the skin, can be provided. Simple Explanation of the Diagram

[0016] The present invention should become more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustrative and explanatory purposes only and are not intended to define the scope of the invention. The scope of this invention is defined by the appended claims. [Figure 1] is a schematic perspective view of a nonwoven fabric related to an embodiment of the present invention. [Figure 2] is a schematic enlarged top view of a portion of the nonwoven fabric, shown in conceptual form. [Figure 3A] is a partial enlarged view of part III of Figure 2. [Figure 3B] is a partial enlarged view used for explanation of the connection part of Figure 3A. [Figure 4] is a schematic side view illustrating the absorption of liquid released from the sample into the defatted cotton during the liquid release rate test. [Figure 5] is a schematic top view of a sample cut from nonwoven fabric used to determine the static friction coefficient between liquid-impregnated nonwoven fabrics. [Figure 6] is a schematic top view of the nonwoven fabric cut out of the nonwoven material used to measure the static friction coefficient between liquid-impregnated nonwoven fabrics. [Figure 7] is a schematic top view illustrating the state of the sample used to determine the static friction coefficient between liquid-impregnated nonwoven fabrics. [Figure 8] is a schematic side view illustrating the test apparatus used to determine the static friction coefficient between liquid-impregnated nonwoven fabrics. [Figure 9] is a schematic top view of a sample cut from nonwoven fabric used to determine the static friction coefficient between liquid-impregnated nonwoven fabric and artificial skin sheet. [Figure 10] is a schematic top view of a sample cut from a nonwoven fabric used to measure the nap length of a nonwoven fabric produced by friction. [Figure 11] is a schematic top view illustrating the state of the sample used to determine the elongation of nonwoven fabric. Implementation

[0017] The nonwoven fabric of the present invention comprises: cellulose-based fibers, adhesive core-sheath type composite fibers having an adhesive portion, and non-adhesive core-sheath type composite fibers having an ethylene-vinyl alcohol copolymer in the sheath portion.

[0018] (Cellulose-based fibers) Examples of cellulose-based fibers include plant fibers such as cotton, hemp, and pulp; regenerated fibers such as rayon and cupro; and refined cellulose fibers such as lyocell (Tencel). These cellulose-based fibers can be used alone or in combination of two or more. Among them, rayon is preferred in terms of ease of acquisition and handling. Furthermore, while cellulose-based fibers can be partially fibrillated, it is desirable to avoid the adhesion of fine fibers to the face, ideally, they should not be substantially fibrillated.

[0019] The content of cellulose-based fibers relative to the total weight of the nonwoven fabric of the present invention is 45% by mass or more and less than 90% by mass. If the content of cellulose-based fibers is less than 45% by mass, the water retention capacity is reduced. On the other hand, if the content of cellulose-based fibers relative to the total weight of the nonwoven fabric of the present invention is 90% by mass or more, the sheet becomes high-density, and the liquid release capacity is reduced. Preferably, the content of cellulose-based fibers relative to the total weight of the nonwoven fabric can be 50% by mass or more and less than 90% by mass, more preferably 55% by mass or more and less than 88% by mass, and particularly preferably 65% ​​by mass or more and less than 85% by mass.

[0020] There is no particular limitation on the fineness of cellulose fibers, for example, it can be 1.2~2.2 dtex, more preferably 1.5~1.9 dtex. There is no particular limitation on the average fiber length of cellulose fibers, but from the point of view of manufacturing workability and the mechanical properties of nonwoven fabrics, it can be 10~100 mm, more preferably 20~80 mm, and more preferably 30~60 mm.

[0021] (Next, core-sheath type composite fibers) The nonwoven fabric of this invention contains, relative to the total mass of the nonwoven fabric, 5% to 20% by mass of adhesive core-sheath type composite fibers, wherein the aforementioned adhesive core-sheath type composite fibers have an adhesive portion bonded at their intersection points. In the adhesive portion, the sheaths of the fibers can be integrated, thus imparting good morphological stability.

[0022] By including adhesive core-sheath type composite fibers in a specific ratio, the adhesive portion can be formed within an appropriate range, thereby improving the morphological stability of the nonwoven fabric. Furthermore, the adhesive portion, through the fusion of the sheaths of the adhesive core-sheath type composite fibers, can form an integrated, mesh-like structure, thus suppressing fuzzing of the nonwoven fabric under friction. The content of adhesive core-sheath type composite fibers is preferably 7% by mass or more and 17% by mass or less, and more preferably 8% by mass or more and 15% by mass or less.

[0023] The core-sheath type composite fiber system is composed of resin components forming the core and resin components forming the sheath, with the sheath portion possessing adhesive properties. Various resin components can be used in the sheath portion as long as they can form an adhesive portion, but from a workability point of view, the sheath portion should preferably have heat-melt adhesive properties. Examples of preferred sheath portions include: polyolefin resins such as polyethylene, polypropylene, modified polymers, mixtures, and copolymers thereof, which have heat-melt adhesive properties; modified polyesters (e.g., modified polyethylene terephthalate modified with isophthalic acid); and more preferably, mixtures and copolymers of polyethylene and modified polymers of polyethylene, modified polyethylene terephthalate, etc. For example, when a heat-adhesive resin is used as the sheath, the melting point of the heat-adhesive resin may be, for example, 80~150°C, and more preferably 100~140°C.

[0024] On the other hand, as for the core, there are no limitations as long as it can be fiberized with the sheath forming the bond, and can still be used as a fiber even when the sheath forms the bond. Appropriate resin components can be selected for the sheath. Preferred core components include, for example, polyolefin resins such as polypropylene, and polyester resins such as polyethylene terephthalate. When a heat-adhesive resin is used for the sheath, the melting point of the resin component in the core can be, for example, 10°C or more higher than the melting point of the resin component in the sheath, preferably 20°C or more, and more preferably 30°C or more.

[0025] For example, suitable core / sheath combinations include polyethylene terephthalate (PET) / polyethylene (PE), PET / modified PET, polypropylene (PP) / PE, and PP / modified PP. Due to their low cost, the PP / PE combination, commonly used in nonwoven fabrics, is particularly preferable.

[0026] From the perspective of forming a strong bond, in the core-sheath type composite fiber, the low-melting-point component that forms the sheath preferably covers at least 40% of the periphery of the core, and particularly at least 60%. Furthermore, the composition ratio of the core to the sheath, by mass, can be, for example, 90 / 10 to 10 / 90, more preferably 80 / 20 to 20 / 80, and even more preferably 70 / 30 to 30 / 70.

[0027] The cross-sectional shape of the aforementioned core-sheath type composite fiber is not particularly limited and can be any shape, such as a circular core-sheath, an eccentric core-sheath, or an irregularly shaped core-sheath. The fineness of the core-sheath type composite fiber, based on the viewpoint of improving morphological stability, can be, for example, 0.5~10.0 dtex, preferably 1.0~5.0 dtex, and even more preferably 1.4~2.2 dtex. The average fiber length of the core-sheath type composite fiber, from the perspective of manufacturing workability and the mechanical properties of the nonwoven fabric, is preferably in the range of 10 mm~80 mm. More preferably, it is 30 mm~70 mm, and even more preferably 35 mm~60 mm. In the core-sheath type composite fiber, by using such short fibers, the mechanical properties of the nonwoven fabric, such as strength and elongation, can be improved while increasing the mobility and interlacing degree of the fibers derived from the interlacing process.

[0028] (Non-bonded core-sheath type composite fiber) The nonwoven fabric of this invention, in addition to the aforementioned cellulose fibers, contains a non-bonded core-sheath type composite fiber in which the sheath portion has a resin possessing both hydrophilic and oleophilic properties. That is, the sheath portion contains an ethylene-vinyl alcohol copolymer (EVOH), which is the aforementioned hydrophilic and oleophilic resin. Unlike the aforementioned bonded core-sheath type composite fibers, in the non-bonded core-sheath type composite fiber, the ethylene-vinyl alcohol copolymer in the sheath portion exists immiscibly within the nonwoven fabric. The presence of this non-bonded core-sheath type composite fiber enhances the elasticity of the nonwoven fabric.

[0029] The EVOH used in the sheath of the non-bonded core-sheath type composite fiber of the present invention is preferably obtained by saponifying an ethylene-vinyl ester copolymer. The EVOH composition preferably has an ethylene content of 25-70 moles. Based on the viewpoint of possessing both hydrophilic and lipophilic properties, an ethylene content of 30-65 moles is particularly preferred.

[0030] By using non-bonded core-sheath type composite fibers with EVOH as the sheath, the liquid retention (water retention) of nonwoven fabrics containing liquid components can be improved, and the liquid release can also be improved when the nonwoven fabric is compressed by 30%.

[0031] In non-bonded core-sheath type composite fibers, the core only needs to be a resin component that can be fiberized with EVOH. There are no particular limitations. However, based on the viewpoint of giving rigidity to hydrophilic EVOH, it is preferable to use a hydrophobic resin component.

[0032] Examples of hydrophobic resin components include polyester resins such as polyethylene terephthalate, polyolefin resins such as polypropylene, and polyamide resins. Based on the viewpoint that polypropylene and polyester resins have higher rigidity than EVOH, polyester resins are preferred. Based on the viewpoint that polyester resins have higher elasticity than EVOH and can improve the morphological stability of nonwoven fabrics, polyester resins are preferred.

[0033] By using non-bonded core-sheath composite fibers, spaces can be formed within the nonwoven fabric to retain liquid. This not only controls liquid leakage but also reduces friction between the nonwoven fabric and the skin due to the non-bonded points, thus lessening skin burden. Furthermore, even when compressed by about 30%, the nonwoven fabric can be given an appropriate compressive stiffness that is neither too stiff nor too soft.

[0034] From the perspective of imparting both hydrophilicity and oleophilicity to the fiber surface and controlling liquid release, in non-bonded core-sheath type composite fibers, it is preferable that the EVOH forming the sheath covers at least 50% of the periphery of the core, especially at least 70%. Furthermore, the composition ratio of the core to the sheath, by mass, can be, for example, 90 / 10 to 10 / 90, more preferably 80 / 20 to 20 / 80, and even more preferably 70 / 30 to 30 / 70.

[0035] The cross-sectional shape of the aforementioned non-bonded core-sheath composite fiber is not particularly limited; it can be a round core-sheath, an eccentric core-sheath, an irregularly shaped core-sheath, etc., and can be of any shape. The fineness of the non-bonded core-sheath composite fiber, from the perspective of processability and skin contact, can be, for example, 0.5~10.0 dtex, preferably 1.0~5.0 dtex, and more preferably 1.4~2.2 dtex. The average fiber length of the non-bonded core-sheath composite fiber, from the perspective of manufacturing workability and the mechanical properties of the nonwoven fabric, is preferably in the range of 10 mm~80 mm. Preferably 30 mm~70 mm, and more preferably 35 mm~60 mm. In non-bonded core-sheath composite fibers, by using such short fibers, the mechanical properties of the nonwoven fabric, such as strength and elongation, can be improved while increasing the fiber mobility and interlacing degree caused by the interlacing process.

[0036] The content of non-adhesive core-sheath type composite fibers is expressed as the mass ratio of the content of cellulose fibers (T) to the content of non-adhesive core-sheath type composite fibers (N). For example, T / N can be 99 / 1 to 51 / 49, preferably 95 / 5 to 55 / 45, more preferably 95 / 5 to 65 / 35, and even more preferably 95 / 5 to 75 / 25.

[0037] Figure 1 is a perspective view illustrating a nonwoven fabric related to one embodiment of the present invention. Figure 2 is an enlarged top view showing a portion of the nonwoven fabric in conceptual form. Figure 3A is a partial enlarged view of part III of Figure 2, and Figure 3B is a partial enlarged view illustrating the joining part of Figure 3A.

[0038] As shown in Figure 1, the nonwoven fabric 10 of the present invention comprises: cellulose fibers 13, bonded core-sheath type composite fibers 11, and unbonded core-sheath type composite fibers 14. These fibers 11, 13, and 14 can be arranged randomly in the nonwoven fabric, or they can be arranged predominantly in any direction (e.g., the MD direction). In the nonwoven fabric 10, the bonded core-sheath type composite fibers 11 are bonded to each other at their intersecting points to maintain the shape of the nonwoven fabric.

[0039] Figure 2 is a partially enlarged top view of Figure 1, illustrating the presence of bonded core-sheath type composite fibers 11 and non-bonded core-sheath type composite fibers 14 in the nonwoven fabric. In Figure 2, the bonded core-sheath type composite fibers 11 and non-bonded core-sheath type composite fibers 14 are conceptually represented as lines. Cellulose fibers 13 are also distributed as lines in the nonwoven fabric, but are omitted from the diagram as lines. Furthermore, for simplicity, they are shown as straight lines in the diagram; however, all fibers are represented as curves.

[0040] As shown in Figure 2, the core-sheath type composite fiber 11 has a bonding portion 12 that bonds to each other at the intersection with other core-sheath type composite fibers 11. On the other hand, the non-bonded core-sheath type composite fibers 14 do not bond to each other at the intersection with other non-bonded core-sheath type composite fibers 14.

[0041] Furthermore, at the junction of the core-sheath type composite fiber 11 and the non-bonded core-sheath type composite fiber 14, although the two appear to be bonded based on the appearance of the bonded core-sheath type composite fiber, a bonded portion that is mutually soluble is usually not formed at the junction. Similarly, at the junction of the bonded core-sheath type composite fiber 11 and the cellulose fiber 13, a bonded portion that is mutually soluble is usually not formed at the junction.

[0042] As shown in Figure 2, the bonding portion 12 is formed by bonding the core-sheath type composite fibers 11, 11 to each other at their intersecting points, and is present in a plurality of these bonding portions uniformly throughout the entire strip. In other words, the plurality of bonding portions 12 are distributed approximately uniformly throughout the entire strip. In each bonding portion 12, interfiber bonding is formed by fusing or fusion of a portion of the sheath portion 11a of the intersecting core-sheath type composite fibers 11 (the portion at the point of contact) with each other.

[0043] Therefore, unlike simple physical bonding, the adhesive portion 12 can form a fixed point in the nonwoven fabric. Thus, even when the nonwoven fabric is stretched, the adhesive portion 12 serves as a holding part, improving the dimensional stability of the nonwoven fabric. Furthermore, the close proximity of the adhesive portions 12 can form a mesh-like structure, thereby suppressing overstretching during use.

[0044] Specifically, as shown in Figures 3A and 3B, the core-sheath type composite fiber 11 is a composite fiber comprising a sheath portion 11a and a core portion 11b covered by the sheath portion 11a. The aforementioned bonding portion 12 is formed at the intersection of the sheath portion 11a of one core-sheath type composite fiber 11 and the sheath portion 11a of another core-sheath type composite fiber 11. The sheath portion is only required to be adhesive and is not particularly limited. For example, in the case of a heat-fast core-sheath type composite fiber, the aforementioned core-sheath type composite fiber 11 is suitable as a low-melting-point component as the sheath portion 11a and as a high-melting-point component as the core portion 11b.

[0045] Next, the core-sheath type composite fiber 11 is a circular core-sheath formed by covering the outer circumferential surface of the core 11b, which has a circular cross-sectional shape when viewed from a plane perpendicular to the length direction, with a cylindrical sheath 11a having a generally uniform wall thickness in the circumferential direction. However, as mentioned above, the cross-sectional shape of the core-sheath type composite fiber is not limited to a circular core-sheath shape, and can also be any shape such as an eccentric core-sheath or an irregularly shaped cross-section core-sheath.

[0046] The nonwoven fabric of this invention may include fibers other than the aforementioned cellulose fibers, bonded core-sheath type composite fibers, and non-bonded core-sheath type composite fibers, as long as it does not impair the effects of this invention. Examples of such fibers include polyester fibers, polyolefin fibers, polyamide fibers, acrylic fibers, and polyvinyl alcohol fibers.

[0047] [Manufacturing methods for non-woven fabrics] From the perspective of ensuring space for fiber mixing and impregnation liquid, nonwoven fabric can be obtained by the following method: forming a strip using the various fibers mentioned above in a dry process, then interlacing the fibers in the strip, and further forming an adhesive portion in the adhesive core-sheath type composite fiber by a bonding process.

[0048] Specifically, the aforementioned cellulose fibers, the aforementioned bonded core-sheath type composite fibers, and the aforementioned non-bonded core-sheath type composite fibers are first blended together, and then the fibers are de-fired using a carding machine to produce a strip. This strip can be any of the following: a parallel strip with fibers arranged in the direction of travel of the carding machine; a cross strip formed by interlacing parallel strips; a random strip with random arrangement; or a semi-random strip with an intermediate degree of arrangement between the two. However, considering the increased adaptability to all directions when using the sheet, a random strip is preferred, while a semi-random strip is preferred if high productivity is considered.

[0049] The interlocking process is not particularly limited as long as it can interlock the fibers, but based on the viewpoint that it can achieve dense interlocking of the fibers, it is preferable to perform water interlocking on the resulting strip. Water interlocking process, for example, involves impacting the strip placed on the porous support member described later with a high-pressure columnar jet of water, thereby densely interlocking the constituent fibers of the strip in a three-dimensional manner to integrate them.

[0050] A preferred method for applying three-dimensional cross-flow to a strip is to place the strip on a movable porous support member and apply water flow at a pressure of 0.5–15 MPa once or multiple times. Preferably, the jet holes are arranged in rows on a nozzle plate in a direction orthogonal to the direction of travel of the strip, ensuring uniform water flow impact on the strip. To improve the uniformity of the strip's thickness, it is preferable to use a water pressure, particularly in the range of 1.5–12 MPa, and to further apply water flow cross-flow treatment to both sides of the strip, at least twice on each side and a total of five times or more. Based on the viewpoint of ensuring uniform cross-flow to the strip, the distance between the jet holes and the strip should preferably be 1–10 cm. Furthermore, the water flow can be sprayed, for example, from a nozzle plate with jet holes of 0.05–0.10 mm in diameter and spaced 0.30–1.50 mm arranged in 1–2 rows.

[0051] A porous support member for supporting the strip is, for example, a mesh screen or perforated plate made of metal or resin. From the viewpoint of improving the flatness of the nonwoven fabric surface, it is preferable to perform water flow interlacing on the microfiber fabric structure (e.g., plain weave structure) in at least the final stage of the water flow interlacing process.

[0052] Furthermore, in order to improve the surface flatness of the strip, in the nozzle plate used in the water flow interlacing treatment on the aforementioned porous support member, the nozzle plate used in the final section is preferably composed of spray holes with a diameter of 0.05~0.10 mm and an interval of 0.30~1.00 mm arranged in 1~2 rows. <Next Process> In the bonding process, the interlaced structure in the strip is maintained, and an adhesive portion is formed between the core-sheath type composite fibers. Depending on the resin composition used for the adhesive portion between the core-sheath type composite fibers, the bonding process can be appropriately selected. For example, the adhesive portion can be formed in a solvent that only softens the sheath of the core-sheath type composite fiber, or the core-sheath type composite fiber can be heat-fused, with the sheath being melted by heat treatment to form the adhesive portion. From the viewpoint of simplicity, the heat treatment bonding process is preferred.

[0053] In the case of heat treatment, there are no particular limitations as long as the temperature is controlled to form an adhesive portion for the adhesive core-sheath type composite fibers and not for the non-adhesive core-sheath type composite fibers. Various dryers such as hot air dryers and drum dryers can be used. During the heat treatment process, the temperature of the strip can be adjusted to a temperature higher than the melting point of the sheath portion of the adhesive core-sheath type composite fibers contained in the strip. The strip with the adhesive portion formed can be used as the nonwoven fabric of this invention.

[0054] Furthermore, in the case of heat-fused core-sheath type composite fibers, a cooling process can be performed to fix the bonding portion. The cooling process can be achieved by appropriately adjusting the time from the heat treatment process to winding, allowing the heat to be released from the strip, or by using a cooling mechanism. To fix the bonding portion, improve the morphological stability of the strip, and prevent fuzzing, it is preferable to wind the strip after the temperature has fallen below the melting point temperature of the sheath of the aforementioned heat-fused core-sheath type composite fiber.

[0055] [Non-woven fabric] The nonwoven fabric of the present invention is a nonwoven fabric containing cellulose fibers, adhesive core-sheath type composite fibers and non-adhesive core-sheath type composite fibers; the aforementioned adhesive core-sheath type composite fibers have adhesive portions bonded at their intersection points; relative to the total mass of the aforementioned nonwoven fabric, the content of the aforementioned adhesive core-sheath type composite fibers is 5% by mass or more and 20% by mass or less, the content of the aforementioned cellulose fibers is 45% by mass or more and less than 90% by mass; and the sheath portion of the aforementioned non-adhesive core-sheath type composite fibers contains ethylene-vinyl alcohol copolymer.

[0056] Based on the considerations of liquid retention properties of nonwoven fabrics, the apparent density of the nonwoven fabric can be, for example, in the range of 0.04 to 0.20 g / cm³, and preferably in the range of 0.06 to 0.15 g / cm³. Here, apparent density is the value of the nonwoven fabric's unit area weight divided by its thickness. If the apparent density of the nonwoven fabric is too low, its morphological stability tends to decrease; conversely, if the apparent density of the nonwoven fabric is too high, its liquid retention tends to decrease. The apparent density of the nonwoven fabric constituting the sheet of the present invention can be calculated from the unit area weight (g / m²) and thickness (mm) (apparent density of nonwoven fabric (g / cm³) = unit area weight (g / m²) / thickness (mm) / 1000). Furthermore, the thickness of the nonwoven fabric is determined according to section 6.2 of JIS L 1913 "General Test Methods for Nonwoven Fabrics".

[0057] The area weight of nonwoven fabric can be in the range of 10~100 g / m2, preferably in the range of 20~100 g / m2, and even more preferably in the range of 25~50 g / m2. When the area weight of nonwoven fabric is too low, its morphological stability decreases, and when used as liquid-impregnated sheets, it tends to curl easily. On the other hand, when the area weight of nonwoven fabric is too high, the amount of fiber and impregnation liquid used per sheet will increase, which tends to be disadvantageous in terms of cost.

[0058] There are no particular limitations on the thickness of nonwoven fabrics; for example, it can be in the range of 0.05 to 10 mm, preferably in the range of 0.10 to 8 mm, and even more preferably in the range of 0.20 to 5 mm. When the thickness is too thin, it tends to be difficult to maintain the shape of the nonwoven fabric; when the thickness is too thick, the sheet-like fiber aggregates will become too thick, and the inter-fiber complexion tends to be insufficient.

[0059] In a nonwoven fabric of this type, the core-sheath type composite fibers are contained in a specific range of content, and a bonding portion is formed at the intersection of the core-sheath type composite fibers, thus the nonwoven fabric exhibits excellent morphological stability. For example, the nonwoven fabric of the present invention has an elongation of, for example, 40% or less, preferably 35% or less, and more preferably 31% or less. Although the elongation can be 0%, in applications where the nonwoven fabric requires stretchability, the elongation is 5% or more, preferably 10% or more. Furthermore, the elongation is a value measured by the method described in the embodiments described later.

[0060] A nonwoven fabric of a certain type contains cellulose fibers and non-bonded core-sheath type composite fibers with EVOH in the sheath at a specific range of content, thus enabling control over liquid release properties when compressed to 30% thickness. After impregnating the nonwoven fabric with a mixture of distilled water and glycerin (distilled water / glycerin mass ratio = 5 / 4) at 500% by mass and allowing it to stand for 24 hours, the liquid release rate within 10 seconds of 30% compression deformation is, for example, 7-14%, preferably 8-12%. If the liquid release rate is too low, the liquid release properties deteriorate; if the liquid release rate is too high, liquid dripping may occur due to liquid release. Furthermore, the liquid release rate is a value measured according to the method described in the examples below.

[0061] According to a given pattern of nonwoven fabric, containing cellulose fibers within a specific range, and where the non-bonded core-sheath type composite fibers do not have substantially interlocking bonding portions, sufficient space for moisture retention within the nonwoven fabric can be ensured. Therefore, the water retention rate of the nonwoven fabric can be, for example, 1145% or more, preferably 1180% or more, and more preferably 1200% or more. There is no particular upper limit to the water retention rate; for example, it can be around 1500%. Furthermore, the water retention rate is a value measured according to the method described in the embodiments below.

[0062] According to a given sample of nonwoven fabric, which contains cellulose fibers and non-bonded core-sheath type composite fibers with EVOH in the sheath portion within a specific range, the compression hardness can be, for example, 0.750~1.500 N / mm, preferably 0.800~1.400 N / mm, and more preferably 0.850~1.300 N / mm. Furthermore, the compression hardness is a value measured by the method described in the examples below. If the compression hardness is too low, there is a possibility of excessive liquid release during use, for example, due to the act of grasping and removing the sheet from the packaging, or the act of folding it, there is a possibility of liquid release before use. On the other hand, if the compression hardness is too high, the liquid release rate is easily reduced.

[0063] According to a certain pattern of nonwoven fabric, a pseudo-net-like state may be formed to suppress the occurrence of pilling. The length of the pilling occurring in the nonwoven fabric may be, for example, 7.0 mm or less, preferably 6.5 mm or less, and more preferably 3.0 mm or less. Furthermore, the length of the pilling is a value measured by the method described in the embodiments below. Furthermore, even when the nonwoven fabric is thin, the length of the fuzz that occurs can be suppressed. The length of the fuzz that occurs in the nonwoven fabric relative to the thickness of one sheet of nonwoven fabric can be, for example, less than 10 times, preferably less than 8 times, and even more preferably less than 5 times.

[0064] For a given type of nonwoven fabric, it is desirable that the nonwoven fabrics do not slip when folded and used. Therefore, the static friction coefficient (A) between the nonwoven fabrics can be, for example, 0.0550~0.0900, more preferably 0.0600~0.0900, and even more preferably 0.0650~0.0880. Furthermore, the static friction coefficient (A) between the nonwoven fabrics is a value measured by the method described in the following embodiments, with the nonwoven fabric used in a state containing 400% by mass of distilled water.

[0065] According to a given type of nonwoven fabric, it is preferable to have slipperiness when applied to the skin, so the static friction coefficient (C) between the nonwoven fabric and the bioskin can be, for example, 0.0450 or less, and more preferably 0.0430 or less. Furthermore, the static friction coefficient (C) between the nonwoven fabric and the bioskin is a value measured by the method described in the following embodiments, wherein the nonwoven fabric is used with 400% by mass of distilled water during the measurement.

[0066] According to a certain type of nonwoven fabric, it is preferable that when the nonwoven fabric is folded and applied to the skin, the nonwoven fabric does not slide against each other, but has sliding properties relative to the skin. Therefore, the difference (AC) between the static friction coefficient (A) of the nonwoven fabric and the static friction coefficient (C) of the nonwoven fabric and the bioskin can be, for example, 0.0170~0.1000, preferably 0.0200~0.0900, and more preferably 0.0300~0.0800.

[0067] [Liquid-impregnated thin films] This invention includes liquid-impregnated sheets made from the aforementioned nonwoven fabric. The liquid-impregnated sheets contain at least the aforementioned nonwoven fabric and the liquid described below, and can be conveniently used for cleaning, cosmetic, medical, household, and industrial purposes.

[0068] The liquid used for these purposes may be appropriately selected according to the application, and may be a solution, dispersion, or emulsion containing a known or commonly used active ingredient. The liquid may be an aqueous liquid such as water, aqueous solution, or aqueous emulsion, or an oily liquid using an organic solvent or the like as a medium, or a mixture thereof.

[0069] The amount of liquid used for impregnation is not particularly limited as long as it achieves the desired effect, and can be appropriately selected according to the purpose. The amount of liquid impregnation, relative to 100 parts by weight of the aforementioned nonwoven fabric, can be, for example, 100 to 1000 parts by weight, and preferably 150 to 800 parts by weight.

[0070] As an active ingredient, various cosmetic ingredients, cleaning ingredients, washing ingredients, disinfecting ingredients, medicinal ingredients, cooling ingredients, insecticidal ingredients, coating agents, coatings, finishing agents (such as gloss agents, etc.) can be used depending on the application. These active ingredients can be used alone or in combination of two or more.

[0071] Furthermore, as an active ingredient, known or commonly used active ingredients can be used. Depending on the type and purpose of the active ingredient, appropriate solvents (water, ethanol, glycerin, propylene glycol, dipropylene glycol, butylene glycol, etc.), auxiliaries (emulsifiers, chelating agents, pH adjusters, neutralizers, thickeners, lubricants, crystallization rate retarder, etc.), additives (UV absorbers, powders, antioxidants, preservatives, fragrances, fluorescent whitening agents, antistatic agents, flame retardants, deodorizers, plasticizers, colorants, etc.) can be used.

[0072] As cosmetic ingredients (ingredients used to improve body appearance), examples include whitening ingredients, anti-aging (antioxidant, anti-wrinkle, anti-sagging) ingredients, anti-inflammatory (soothing, anti-allergic) ingredients, cell-activating (promoting metabolism, repairing DNA damage) ingredients, moisturizing ingredients, softening ingredients, astringent ingredients, exfoliating ingredients, blood circulation promoting ingredients, antioxidant ingredients, and warming ingredients. As superior cosmetic ingredients, examples include arbutin, lycopene, vitamin A, vitamin C, vitamin E, astaxanthin, resorcinol, acetylglucosamine, ellagic acid, tranexamic acid, linoleic acid, hydroxyproline, hydroxypyrrolidone, tocopherol and its derivatives, water-soluble polymers, amino acids, EGF peptides, sugar alcohols, sugars, mucopolysaccharides, various plant extracts, placental extracts, capsaicin, etc.

[0073] Examples of cleansing ingredients include: nonionic surfactants for skin cleansing purposes, alcohols (ethanol, polyols, etc.), glycol ethers, and oils (mineral oils, ester oils, waxes, silicone oils, natural oils, etc.).

[0074] In addition to the cleaning agents mentioned above, other cleaning agents that can be listed as cleaning components include amphoteric surfactants, cationic surfactants, anionic surfactants, solvents, and alkaline agents.

[0075] Examples of disinfectant components include chlorine-based disinfectants (chlorites such as sodium chlorite, hypochlorites such as sodium hypochlorite, chlorates such as sodium chlorate, perchlorates such as sodium perchlorate, and cyanurates such as sodium dichloroisopropylmethylphenol cyanurate), alcohols (ethanol, isopropanol, etc.), amphoteric surfactants, quaternary ammonium salts (benzyl ammonium chloride, benzalkonium chloride, etc.), and chlorhexidine.

[0076] As a medicinal ingredient, various medicinal ingredients can be used depending on the application. For example, as a medicinal ingredient used in wet wipes, examples include anti-inflammatory agents, antihistamines, steroids, analgesics and anti-inflammatory agents, and local anesthetics.

[0077] Examples of cooling ingredients include alcohols such as ethanol, menthol, peppermint oil, peppermint oil, camphor, thymol, and methyl salicylate.

[0078] Examples of insect repellent ingredients include eucalyptus extract, menthol, peppermint oil, and DEET.

[0079] For example, facial masks contain beauty ingredients and solvents, and may also contain other active ingredients, auxiliaries, additives, etc., if necessary. Cleansing sheets contain cleansing ingredients, and may also contain other effective ingredients (such as beauty ingredients), solvents, auxiliaries, additives, etc., if necessary. Cleaning wipes contain cleaning agents and may also contain other active ingredients (coating agents, finishing agents, coatings, etc.), solvents, additives, etc., if necessary. Disinfecting and virus-removing wipes contain disinfectant ingredients, and may also contain other effective ingredients (moisturizing ingredients, etc.), solvents, auxiliaries, additives, etc., as needed. Antipruritic tablets contain medicinal ingredients, and may also contain other effective ingredients (cooling ingredients, moisturizing ingredients, etc.), solvents, auxiliaries, additives, etc., as needed. Antiperspirant sheets contain cooling ingredients and may also contain other effective ingredients (astringents, moisturizing ingredients, etc.), solvents, auxiliaries, additives, etc., as needed. Insect repellent tablets contain insecticidal ingredients, and may also contain other effective ingredients (such as moisturizing ingredients), solvents, auxiliaries, additives, etc., as needed.

[0080] In particular, the nonwoven fabric of this invention, in addition to being able to fully impregnate the intended liquid, exhibits excellent liquid release properties during use and excellent shape stability. For example, it can be conveniently used as a coating sheet (especially a wiping sheet). For instance, when used as a coating sheet, it can prevent the folded nonwoven fabric from sliding against each other, thus facilitating use in the folded state even at a larger size than usual. For example, in such a case, the size of a single sheet can be, for example, 200 cm² or more, preferably 250 cm² or more. The size of a single sheet can be appropriately selected according to the application; for example, in the case of skin care applications, the upper limit of the size of a single sheet can be, for example, around 1000 cm².

[0081] Furthermore, the liquid-impregnated sheet of the present invention, with its excellent water retention, liquid release rate, and pleasant skin feel, and containing the aforementioned active ingredients, is useful as a skin care sheet for use on the skin. As a skin care sheet, it can be a sheet for rubbing the skin, or a sheet for non-rubbing purposes, where the skin is not rubbed.

[0082] The liquid-impregnated sheet of the present invention can be used as a non-rubbing sheet, or as a cosmetic sheet impregnated with cosmetic ingredients (e.g., cosmetic mask sheet, nail care sheet, scalp care sheet, body care sheet for back, chest, abdomen, etc., sanitary sheet, etc.), or as a pharmaceutical or therapeutic sheet (anti-itch sheet, wet cloth, etc.).

[0083] On the other hand, by using nonwoven fabric with appropriate compression hardness and liquid release rate (especially nonwoven fabric that can suppress pilling due to friction) as the base material, the liquid-impregnated sheet of the present invention can also be used appropriately and conveniently as a sheet for rubbing purposes. As a sheet for rubbing purposes, it can be used as a makeup remover sheet or cleansing sheet impregnated with wiping and cleaning ingredients, a body wash sheet (sweat wipe, antiperspirant sheet, hair, scalp wipe, buttock wipe, sanitary sheet, etc.), an insect repellent sheet, a cooling sheet, a medicinal or therapeutic sheet (anti-itch sheet, etc.), etc. Especially in the case of removing eye makeup, although the amount of makeup ingredients to be removed from such a delicate skin area as the eyelids is relatively large due to heavy eye makeup, the liquid-impregnated sheet of the present invention does not burden the skin, can release liquid sufficiently, and utilizes ethylene-vinyl alcohol copolymer to take into account both lipophilic and hydrophilic properties, making it particularly useful as a makeup remover sheet. [Example]

[0084] The present invention will now be described in more detail using examples, but the invention is not limited to these examples in any way. Furthermore, in the following examples and comparative examples, various physical properties were measured using the methods described below.

[0085] [Weight per unit area and apparent density] According to JIS L 1913 "General Test Methods for Nonwoven Fabrics", section 6.2, the weight per unit area (g / m2) is determined. Furthermore, the apparent density (g / cm3) is calculated by dividing the weight per unit area by the thickness.

[0086] [thickness] Referring to JIS L 1913, the thickness of the nonwoven fabric was measured using a thickness measuring device with a circular horizontal plate of 25.4 mm in diameter when a load of 12 g / cm2 was applied. This thickness was then used as the thickness of the nonwoven fabric.

[0087] [Water retention capacity] The water retention rate was determined according to JIS L 1913 6.9.2 (water retention rate). The test piece was cut into 10 cm squares, and its mass X (g) was measured. This test piece was then immersed in water for 15 minutes. Afterward, the test piece was removed from the water by holding one side, and its mass Y (g) was measured after 1 minute. The water retention rate (g) was calculated from these values ​​using the following formula. Water retention capacity (g) = YX

[0088] Water retention rate The water retention rate (%) is calculated as a percentage obtained by dividing the water retention amount by the mass of the test piece before immersion in water, and is given by the following formula. Water retention rate (%) = (YX) / X × 100

[0089] [Compression Hardness] The compressive hardness at 30% compression deformation was determined using the following procedure. (1) Cut the test sample into 8 pieces of 5 cm square and measure the mass of the 8 pieces. (2) Overlap 8 test pieces, and mix distilled water (Fujifilm Wako Pharmaceutical Co., Ltd. Product No. 042-16973) and glycerin (KENEI Pharmaceutical Co., Ltd. Glycerin P "KENEI") at a ratio of 5 parts distilled water to 4 parts glycerin (mass ratio). Drop 0.3 cc at a time from a height of 2 cm onto the test piece, and after 500% by mass has been dropped, let it soak into the entire surface of the thin film. (3) Let the mixture stand in a sealed environment where it will not evaporate until the liquid travels throughout the 8 pieces by capillary action, and leave for 24 hours. (4) After 24 hours, the sample was taken out and, in accordance with JIS L 1913, the original state of the 8 overlapping pieces was measured with a thickness measuring instrument of a circular horizontal plate with a diameter of 25.4 mm when a load of 16 g / cm2 was applied. (5) Subsequently, the sample was tested using a YAWASA measuring instrument Type MSES-0512-1-SL manufactured by Tech Co., Ltd., under the conditions of an indenter diameter of 20.0 mm, an indentation speed of 1.0 mm / s, and a maximum load of 5.0 N. The rebound stress was measured at the center of the sheet. (6) Based on the obtained data, take the thickness E (mm) of the sheet × 30% of the strain F (mm) as the center, and read the stress (N) that occurs when the strain changes by 0.25 mm above and below it. Divide the difference by 0.5 mm and take the value as the compressive hardness (N / mm) when the compression deformation is 30%.

[0090] [Discharge rate] The liquid release rate at 30% compression deformation was determined using the following procedure. (1) Cut the test sample into 8 pieces of 5 cm square and measure the mass G (g) of the 8 pieces. (2) Overlap 8 test samples and mix distilled water (Fujifilm Wako Pharmaceutical Co., Ltd. Product No. 042-16973) and glycerin (KENEI Pharmaceutical Co., Ltd. Glycerin P "KENEI") at a ratio of 5 parts distilled water to 4 parts glycerin (mass ratio). Drop 0.3 cc at a time from a height of 2 cm onto the test sample, 500% by mass, so that the mixture is fully impregnated on the surface of the thin film. (3) Let the mixture stand in a sealed environment where it will not evaporate until the liquid has permeated all 8 pieces through capillary action, and leave for 24 hours. (4) After 24 hours, take out the sample and, referring to JIS L 1913, measure the thickness E (mm) of the 8 overlapping samples under a 25.4 mm diameter circular horizontal plate when a load of 16 g / cm2 is applied. (5) Place the sample on the measuring table, place the defatted cotton H (g) with the pre-measured mass at a position 2 cm away from the sample, and slowly slide the pressure plate to clamp the sample and the defatted cotton until the thickness E (mm) of the sample is reached. (6) As shown in Figure 4, rotate the measuring stage 90 degrees to make the sample vertical. Figure 4 is a schematic side view illustrating the absorption of liquid released from the sample into the absorbent cotton during the liquid release rate test. After rotation, the measuring stage 24 holds the sample 20 and the absorbent cotton 22 vertically and continuously. Since the sample 20 is positioned on the upper side of the absorbent cotton 22, when the sample 20 is compressed due to the movement of the pressure plate 23, the mixture released from the sample 20 is absorbed by the absorbent cotton 22. (7) Specifically, the pressure plate 23 is moved at a speed of 0.2 mm / sec to compress the sample 20 for a total of 10 seconds from the position where the sample thickness E is compressed by 30% in the thickness direction, and the mixture released from the sample 20 is absorbed by the degreased cotton 22. (8) Measure the mass I (g) of the defatted cotton 22 after absorbing the mixed liquid. Therefore, the liquid release rate J (%) of the sample is calculated by the following formula. Discharge rate J (%) = (IH) / (G × 5) × 100

[0091] [Coefficient of static friction between liquid-impregnated nonwoven fabrics] Friction was measured using a precision universal testing machine (Autograph AGS-D type, manufactured by Shimadzu Corporation) in accordance with ASTM-D1894.

[0092] First, as shown in Figures 5 and 6, samples 30 (4.0 cm in the MD direction × 6.0 cm in the CD direction) and a friction-bearing member 35 (6.0 cm in the MD direction × 12.0 cm in the CD direction) are prepared from the obtained non-woven fabric. In sample 30 of Figure 5, a 1 cm wide section from the end in the CD direction is used as a gripping portion 31a, and the remaining 5 cm wide section is used as a grounding portion 31b. In friction-bearing member 35 of Figure 6, a 1 cm wide section from the end in the CD direction is used as a gripping portion 35c, and the remaining 11 cm wide section is used as a grounding portion 35d. Furthermore, assuming it is a cleaning sheet, both sample 30 and friction-bearing member 35 are impregnated with 400 ml of distilled water (Fujifilm Wako Pharmaceutical Co., Ltd. Product No. 042-16973).

[0093] Next, as shown in Figures 7 and 8, a sample 30 is placed on the friction member 35, and the gripping part 31a of the sample 30 is held by a clamp 36. Under the condition that a specific load is applied by the weight 38 through the acrylic plate 37, the sample 30 is stretched in the direction of the arrow to carry out the test.

[0094] Specifically, in a precision universal testing machine equipped with a load cell 32, a friction component 35 is placed on a stage 39, and a sample 30 is placed on the friction component 35. The sample 30 and the friction component 35 are respectively provided with gripping parts 31a and 35c in reverse orientation, and these gripping parts 31a and 35c are held by a clamp 36.

[0095] Next, an acrylic plate 37 of the same size is placed on the area (ground part) of the sample 30, which is MD4.0 cm × CD5.0 cm. Under the condition that the acrylic plate 37 and the weight 38 are combined to apply a load of 3.75 g / cm2, the polyamide wire 34 is stretched in the horizontal direction via the pulley 33, thereby stretching the sample 30 horizontally in the CD direction at a speed of 100 mm / min. The static friction coefficient is calculated from the obtained test force.

[0096] [Coefficient of static friction between liquid-impregnated nonwoven fabric and artificial skin] Friction was measured using a precision universal testing machine (Autograph AGS-D type, manufactured by Shimadzu Corporation) in accordance with ASTM-D1894.

[0097] First, as shown in Figure 9, the obtained nonwoven fabric is prepared to be cut into a sample 30 with a diameter of 4.0 cm in the MD direction and a diameter of 11.0 cm in the CD direction. In the sample 30 of Figure 9, a 1 cm wide portion from the end in the CD direction is taken as the gripping portion 31a, and the remaining 10 cm wide portion is taken as the grounding portion 31b. Furthermore, it is assumed to be a clean sheet, and the sample 30 is impregnated with 400 ml of distilled water (Fujifilm and Hikari Pharmaceutical Co., Ltd. Product No. 042-16973).

[0098] Next, as shown in Figures 7 and 8, a sample 30 is placed on the friction member 35, and the gripping part 31a of the sample 30 is held by a clamp 36. Under the condition that a specific load is applied by the weight 38 through the acrylic plate 37, the sample 30 is stretched in the direction of the arrow (CD direction) for the test.

[0099] In this experiment, except that (i) the artificial skin Bioskin plate (product number P001-001) manufactured by BEAULAX Co., Ltd. was used as the friction component 35, (ii) the grounding part of the sample 30 was set to a range of MD4.0 cm × CD10.0 cm, and (iii) the total load of the acrylic plate 37 and the weight 38 of the same size placed on the grounding part was set to 5 g / cm2, the static friction coefficient was calculated by conducting a test with the same static friction coefficient as that between the sample and the nonwoven fabric.

[0100] [Long fuzz] The burr length was measured using a precision universal testing machine (Autograph AGS-D type manufactured by Shimadzu Corporation) in accordance with ASTM-D1894.

[0101] First, as shown in Figure 10, the obtained nonwoven fabric is prepared to be cut into a sample 30 with a width of 7.0 cm in the MD direction and 4.0 cm in the CD direction. In the sample 30 in Figure 10, a 1 cm wide portion is taken from the end in the MD direction as the gripping portion 31a, and the remaining 6 cm wide portion is taken as the grounding portion 31b.

[0102] Next, as shown in Figures 7 and 8, a sample 30 is placed on the friction member 35, and the gripping part 31a of the sample 30 is held by a clamp 36. Under the condition that a specific load is applied by the weight 38 through the acrylic plate 37, the sample 30 is stretched in the direction of the arrow to carry out the test.

[0103] In this test, except that (i) the water-resistant file #1000 from Sankyo Chemical Co., Ltd. was used as the friction component 35, and (ii) the grounding part of the sample 30 was set to the range of MD6.0 cm × CD4.0 cm, the same test was conducted as the static friction coefficient between sheets, and the sample was stretched 10 cm in the MD direction at a speed of 100 mm / min in the horizontal direction.

[0104] Then, the sample is removed from the testing machine, and the sample 30 is fixed in a vertical position with the gripping part 31a as the upper side. From the MD direction end of the sample's grounding part 31b, where the nap can be visually confirmed, the lengths of five naps in order from longest to shortest are measured, and their average value is taken as the sample's nap length (mm). Furthermore, the aforementioned nap length is divided by the thickness of the nonwoven fabric to obtain the nap length equal to the average thickness of the nonwoven fabric (1 time). The nonwoven fabric thickness is determined according to JIS L 1913, using a thickness gauge with a circular horizontal plate of 25.4 mm diameter when a load of 12 g / cm² is applied.

[0105] [Elongation] The elongation was determined using a precision universal testing machine (Autograph AGS-D type manufactured by Shimadzu Corporation) according to JIS L 1913 (general short fiber nonwoven fabrics) 6.3.2 (tensile strength and elongation test when wet). As shown in Figure 11, with the gripping interval set to 100 mm, the sample 40 is cut into pieces of 2.5 cm in the MD direction and 12.0 cm in the CD direction. A line is drawn with an oil-based pen at a position of 15 mm from one end in the CD direction, and another line is drawn at a 90 mm interval. The sample 40 is placed in water at 20℃±2℃ until it sinks under its own weight, or after being submerged in water for more than 1 hour. The sample 40, which has absorbed saturated water, is taken out of the immersion solution and immediately gripped at the gripping portions 41a, 41a at both ends of the sample 40 shown in Figure 11, and a tensile stress of 2N is instantaneously applied at a speed of 200 mm / min.

[0106] Then, the sample is removed from the testing machine and fixed in a vertical position with the gripping part 41a on one side as the top. The distance between the lines K (mm) is measured. The elongation L (%) is calculated by the following formula. Elongation L (%) = K / 90 × 100 - 100

[0107] [Related experiments on user experience] (sample) Fold a 15 cm square sheet into four folds. Prepare a mixture of distilled water (Fujifilm Wako Pharmaceutical Co., Ltd. Product No. 042-16973) and glycerin (KENEI Pharmaceutical Co., Ltd. Glycerin P "KENEI") at a ratio of 5 parts distilled water to 4 parts glycerin (mass ratio). Drop the mixture in 0.3 cc increments from a height of 2 cm onto the sample, ensuring that it is fully absorbed into the sheet. This completes the sample preparation.

[0108] (The evaluator's test) Nine participants (women in their 20s, 30s, and 40s) applied the lipstick "Shiseido MAQUIAGE DRAMATIC ROUGE N RD633" to their lips. With the CD-shaped sample perpendicular to their fingers, one end was held between their index and middle fingers, and the other end between their ring and little fingers. The inside of their middle and ring fingers was used to gently press the sample, and the sample was rubbed twice horizontally without changing the surface of the sample. The evaluation of each sample was conducted based on five criteria: wipeability, skin irritation, shape stability, fuzziness, and resistance to slippage between sheets.

[0109] [Wipe-off properties] Functional tests were conducted according to the above method, and the wiping properties were determined in the following three stages. 〇: The lipstick's fading is satisfactory. △: The way the lipstick fell off was slightly unsatisfactory. ×: The way the lipstick fell off was unsatisfactory.

[0110] [Skin irritation] Based on the above method, a functional test was conducted, and the skin irritation was determined in the following three stages. 〇: Less stimulation △: Slightly more stimulation ×: More stimulation

[0111] [Morphological stability] Functional tests were conducted according to the above method, and the following three-stage determinations were made based on the following criteria. After the test, the 4-fold thin film was expanded, the dimensions in the CD direction were measured, and the expansion from the original 15 cm was calculated. 〇: The expansion is within 5 mm △: Width exceeding 5 mm but within 10 mm ×: Width exceeds 10 mm

[0112] [Fluffiness] Functional tests were conducted according to the above method, and the following three-stage determinations were made based on the following criteria. After the test, the surface was set to horizontal, and the number of fibers that flew out of the surface by more than 3 mm was counted. 〇:0 roots △: 1 or more but less than 5 ×:5 or more

[0113] [The thin sheets do not easily slip against each other] The functional tests were performed according to the above method, and the following three-stage judgments were made based on the following criteria. The number of times the thin film surface was slippery during wiping, but the outermost thin film in contact with the lips did not slip was counted. 0:0 times △: 1 time ×: More than 2 times

[0114] The above five items were evaluated, and the number of people who gave a zero rating in each item was taken as the functional evaluation result. A: 0 indicates 7 or more people B: 〇 represents 4 to 6 people. C: 0 is for 3 people or less

[0115] Furthermore, in cases where nonwoven fabrics are used that have been impregnated with liquids or other components, it is preferable to temporarily remove the impregnated components according to the following procedure before performing the aforementioned physical property determination or evaluation method. Specifically, nonwoven fabric impregnated with liquid components is immersed in a cleaning solution for 2 hours. To remove the components pre-impregnated into the fabric, it is then washed. The amount of cleaning solution is set at 2 L per 100 cm² of the nonwoven fabric. Furthermore, there are no particular limitations as long as the impregnated components can be removed; for example, an ion-exchanged water / neutral detergent ratio of 95 / 5 (volume ratio) can be used as the cleaning solution. For example, Kao (Co., Ltd.) Cucute (trademark) detergent is used. The nonwoven fabric is then left to stand in the liquid. Next, it is immersed in the same amount of ion-exchanged water for 2 hours. After removing the cleaning solution, the nonwoven fabric is air-dried (conditions: 10°C, 65% RH, 24 hours) to minimize changes in its shape, and this dried fabric is used as the test sample.

[0116] (Example 1) The following materials were used: 80 parts by weight of cellulose-based fiber (regenerated cellulose fiber, "HOPE" manufactured by Omikenshi Co., Ltd., 1.7 dtex, 40 mm fiber length); 10 parts by weight of non-bonded core-sheath composite fiber (core composed of polyethylene terephthalate, sheath composed of ethylene-vinyl alcohol copolymer (EVOH), "Sophista" manufactured by Kuraray Co., Ltd., 1.7 dtex, 51 mm fiber length, core-sheath ratio of 50% core to 50% sheath); and 10 parts by weight of bonded core-sheath composite fiber (core composed of polypropylene, sheath composed of polyethylene, "Exsymo Co., Ltd., 1.7 dtex, 51 mm fiber length, core-sheath ratio of 39% core to 61% sheath). After being uniformly blended, a product with a unit area weight of 50 was produced using conventional methods. A semi-random carded strip with a density of g / m² is placed on a perforated cylindrical support with an opening ratio of 25% and an aperture of 0.3 mm. It is continuously conveyed along its length at a speed of 50 m / min while simultaneously undergoing a cross-linking process using high-pressure water jets from above, thus producing a cross-linked fibrous strip (non-woven fabric). During this cross-linking process, two nozzles with 0.10 mm orifices spaced 0.6 mm apart along the width of the strip (the distance between adjacent nozzles is 10 cm) are used. The water pressure of the high-pressure water jets from the first row of nozzles is set to 3.0 MPa, and the water pressure of the high-pressure water jets from the second row of nozzles is set to 4.0 MPa. Furthermore, the strip is placed on a flat support with a fine mesh and continuously conveyed while undergoing the cross-linking process using high-pressure water jets. This interlocking process was performed using two nozzles with 0.10 mm orifices spaced 0.6 mm apart along the width of the strip, both subjected to high-pressure water flow at a pressure of 4.0 MPa. The strip was then dried at 130°C to obtain a water-jet nonwoven fabric with a basis weight of 50.2 g / m².

[0117] (Example 2.3) Except for producing semi-random carded strips with altered fiber composition ratios as shown in Table 1, water-jet nonwoven fabric was obtained in the same manner as in Example 1.

[0118] (Comparative Examples 1-4) Except for producing semi-random carded strips with altered fiber composition ratios as shown in Table 1, water-jet nonwoven fabric was obtained in the same manner as in Example 1.

[0119] (Comparative Examples 5 and 6) Except for the preparation of a semi-randomly combed strip of polyester fiber (Toray Co., Ltd. "Tedoron" T-471, fineness 1.6 dtex, fiber length 51 mm) to replace the non-bonded core-sheath type composite fiber, the water-jet nonwoven fabric was obtained in the same manner as in Example 1.

[0120] (Comparative Example 7) Except for lowering the drying temperature to 110°C, the water-jet nonwoven fabric was obtained in the same manner as in Example 1.

[0121] (Comparative Example 8) Except for increasing the drying temperature to 160°C, the water-jet nonwoven fabric was obtained in the same manner as in Example 1.

[0122]

[0123] As shown in Table 1, in Comparative Example 1, although the elongation could be controlled by forming the adhesive portion with a core-sheath type composite fiber, the proportion of cellulose-based fibers was low, resulting in low water retention. Regarding the compression hardness during liquid impregnation, it was too soft and lacked adequate hardness (elasticity) during compression. In the functional evaluation, the sheets slid against each other during wiping, resulting in insufficient wiping performance.

[0124] In Comparative Example 2, although the elongation could be controlled by forming the adhesive portion using a core-sheath type composite fiber, the high proportion of cellulose fibers resulted in an overly dense structure, leading to low water retention and liquid release rates. Furthermore, the absence of a non-adhesive core-sheath type composite fiber with EVOH in the sheath made it impossible to control the compression stiffness during liquid impregnation, resulting in excessive stiffness during compression. Additionally, there was significant friction between the artificial skin and the liquid-impregnated nonwoven fabric. In the sensory evaluation, the fabric exhibited strong skin irritation, leading to a low liquid release rate and deteriorated wipeability.

[0125] In Comparative Example 3, since it lacks adhesive core-sheath type composite fibers, the elongation cannot be controlled. Therefore, in the functional tests, the morphological stability received a low rating. However, in Comparative Example 3, the densification of the nonwoven fabric caused by cellulose fibers slightly mitigated the decrease in elongation, and compared to Comparative Example 2, the deterioration of liquid release rate and the decrease in water retention rate were also mitigated. However, the obtained nonwoven fabric still had low water retention rate and liquid release rate. In the functional evaluation, due to the lack of adhesive, the morphological stability was poor, the liquid release rate was low, resulting in strong skin irritation and deteriorated scrubbing properties.

[0126] In Comparative Example 4, because it lacks the adhesive core-sheath type composite fiber, the elongation is high, and morphological stability cannot be controlled at all. Furthermore, the same applies to the compression hardness during liquid impregnation; it is too soft and lacks adequate hardness (elasticity) during compression. In the functional evaluation, due to the absence of an adhesive portion, it was particularly evaluated as having poor morphological stability.

[0127] In Comparative Examples 5 and 6, instead of non-bonded core-sheath type composite fibers with EVOH in the sheath, only PET fibers were used. Therefore, in Comparative Example 5, the compression hardness (elasticity) was low, resulting in a high water retention rate but poor liquid release. Furthermore, in Comparative Example 6, compared to Comparative Example 5, the proportion of PET fibers was high and the proportion of cellulose fibers was low. Therefore, the nonwoven fabric could not be densified, resulting in extremely low compression hardness, excessively high liquid release, and pilling.

[0128] In the functional evaluation, Comparative Example 5 was rated as having poor wiping performance due to its low liquid release, while Comparative Example 6, with its high liquid release, not only easily caused liquid dripping, but also resulted in the thin sheets sliding against each other during wiping, thus failing to achieve sufficient wiping performance. Furthermore, its linting properties also received a low rating.

[0129] In Comparative Example 7, although it contains a core-sheath type composite fiber, it lacks an adhesive portion, resulting in a high elongation and completely uncontrollable morphological stability. Furthermore, excessive fuzzing occurs, and the compression hardness during liquid impregnation is also poor, being too soft and lacking adequate hardness (elasticity) during compression. In the functional evaluation, due to the absence of an adhesive portion, not only was the morphological stability particularly poor, but the fuzzing property also received a low rating.

[0130] In Comparative Example 8, not only bonded core-sheath composite fibers but also non-bonded core-sheath composite fibers had bonding portions, resulting in excessive bonding portions and low water retention and liquid release rates. Furthermore, the compression hardness during liquid impregnation could not be controlled, becoming excessively stiff during compression. Additionally, friction between the artificial skin and the liquid-impregnated nonwoven fabric increased. In the sensory evaluation, strong skin irritation led to a low liquid release rate, and the wipeability was also deteriorated.

[0131] On the other hand, regarding Examples 1-3, since the bonding portion is formed in a controlled state, the elongation of the nonwoven fabric can be controlled, thereby improving morphological stability. Furthermore, in addition to morphological stability, the water retention rate and liquid release rate can also be set within appropriate ranges. Moreover, the sheets maintain a specific frictional force against each other, inhibiting slippage between the sheets and reducing friction on the artificial skin on one side. Therefore, even in the case of folding and wiping, good wiping performance can be achieved. Similarly, in functional tests, morphological stability, skin irritation, wiping performance, ease of slippage between the sheets, and fuzzing properties also received high ratings. [Industry availability]

[0132] The nonwoven fabric of this invention has excellent morphological stability, water retention, and liquid release properties, making it suitable and convenient for use as a liquid-impregnated sheet in face masks, coating sheets, and wiping sheets. In particular, although the nonwoven fabric does not easily slip when folded, resulting in excellent operability, the friction between the nonwoven fabric and the skin is also minimal, so even when the sheet is folded, it can be used comfortably.

[0133] As described above, while appropriate embodiments of the present invention have been presented, various additions, modifications, or deletions may be made without departing from the spirit of the present invention, and such additions, modifications, or deletions are still included within the scope of the present invention.

[0134] 10: Non-woven fabric 11: Next, core-sheath type composite fiber 11a: Following the sheath of the core-sheath type composite fiber 11b: Next, the core of the core-sheath type composite fiber 12: Continuing from the previous section 13: Cellulose-based fibers 14: Non-adhesive core-sheath type composite fiber 20, 30, 40: Samples 22: Defatted cotton 23: Pressure plate 24: Measuring stand 35: The component being rubbed 31a, 41a: The grasping part of the sample 31b: Grounding portion of the sample 32: Load cell 33: Pulley 34: Polyamide thread 35c: The gripping part of the friction component 35d: Grounding part of the component being rubbed 36: Fixture 37: Acrylic sheet 38: Weights 39: Platform

Claims

1. A nonwoven fabric comprising cellulose fibers, fibers with adhesive portions, and non-adhesive core-sheath composite fibers, characterized in that: relative to the total mass of the nonwoven fabric, the content of the fibers with adhesive portions is 5% by mass or more and 20% by mass or less; the content of the cellulose fibers is 45% by mass or more and less than 90% by mass; and the fibers with adhesive portions have adhesive portions bonded at their intersection points; the sheath portion of the non-adhesive core-sheath composite fibers contains a resin that is both hydrophilic and oleophilic.

2. The nonwoven fabric as described in claim 1, wherein, The fineness of the aforementioned cellulose fibers is 1.2 to 2.2 dtex.

3. The nonwoven fabric as described in claim 1 or claim 2 has an apparent density in the range of 0.04 to 0.20 g / cm3.

4. The nonwoven fabric as described in claim 1 or claim 2, wherein, The aforementioned fiber with an adhesive portion is an adhesive core-sheath type composite fiber.

5. The nonwoven fabric as described in claim 4, wherein, The sheath of the aforementioned core-sheath type composite fiber contains a heat-adhesive resin, the melting point of which is 80-150°C.

6. The nonwoven fabric as described in claim 4, wherein, The sheath of the aforementioned core-sheath type composite fiber contains a heat-adhesive resin, and the melting point of the resin component in the core of the aforementioned core-sheath type composite fiber is more than 10°C higher than the melting point of the aforementioned heat-adhesive resin.

7. The nonwoven fabric as described in claim 1 or claim 2, wherein, The aforementioned non-bonded core-sheath type composite fiber has a core containing hydrophobic resin components.

8. The nonwoven fabric as described in claim 1 or claim 2, wherein, The aforementioned non-bonded core-sheath type composite fibers do not have a bonding portion that is substantially connected to each other.

9. The nonwoven fabric as described in claim 1 or claim 2, wherein the mass ratio of the content of cellulose fibers (T) to the content of non-bonded core-sheath type composite fibers (N) is T / N = 99 / 1 to 51 / 49.

10. The nonwoven fabric as described in claim 1 or claim 2 has an elongation of 35% or less when absorbing saturated moisture.

11. The nonwoven fabric as described in claim 1 or claim 2, wherein, The compressive hardness at 30% compression deformation after impregnating the nonwoven fabric with a mixture of distilled water and glycerin (distilled water / glycerin mass ratio = 5 / 4) at 500% of the fabric mass and leaving it for 24 hours is 0.750 to 1.500 N / mm.

12. The nonwoven fabric as described in claim 1 or claim 2, wherein, When a mixture of distilled water and glycerin (distilled water / glycerin mass ratio = 5 / 4) is impregnated with the nonwoven fabric at 500% by mass and left for 24 hours, the liquid release rate is 7-14% when the fabric is compressed to 30% of its mass within 10 seconds.

13. The nonwoven fabric as described in claim 1 or claim 2 has a water retention rate of 1145% or higher.

14. The nonwoven fabric as described in claim 1 or claim 2, wherein the difference (AC) between the static friction coefficient (A) of the nonwoven fabric containing 400% by mass of distilled water and the static friction coefficient (C) of the nonwoven fabric containing 400% by mass of distilled water and bioskin is 0.0170 to 0.1000.

15. The nonwoven fabric as described in claim 1 or claim 2, wherein the static coefficient of friction (A) between the nonwoven fabrics containing 400% by mass of distilled water is 0.0550 to 0.0900.

16. The nonwoven fabric as described in claim 1 or claim 2, wherein the static coefficient of friction (C) of the nonwoven fabric containing 400% by mass of distilled water and bioskin is 0.0450 or less.

17. The nonwoven fabric as described in claim 1 or claim 2, wherein, The nap length of the nonwoven fabric with an average thickness (1 times) is less than 10 times that thickness.

18. A liquid-impregnated sheet formed using any one of claims 1 to 17 of the nonwoven fabric.

19. A wiping sheet formed using any one of claims 1 to 17 of the nonwoven fabric.

20. A method for manufacturing a nonwoven fabric, which is the method for manufacturing a nonwoven fabric according to any one of claims 1 to 17, comprising at least: a process of interlacing a strip containing cellulose fibers, fibers having adhesive portions and non-adhesive core-sheath type composite fibers to form a strip having an interlaced structure, wherein, relative to the total mass of the strip, the content of the aforementioned fibers having adhesive portions is 5% by mass or more and 20% by mass or less, and the content of the aforementioned cellulose fibers is 45% by mass or more and less than 90% by mass; and a process of forming adhesive portions between the aforementioned non-adhesive core-sheath type composite fibers but not between the aforementioned fibers having adhesive portions in the strip having the aforementioned interlaced structure.

21. The method for manufacturing nonwoven fabric as described in claim 20, wherein, The aforementioned interlocking process is water flow interlocking.

22. A method for manufacturing a nonwoven fabric as described in claim 20 or claim 21, wherein, In the process of forming the aforementioned adhesive portion, heat treatment is performed at a temperature that is lower than the melting point of the sheath of a non-adhesive core-sheath type composite fiber and higher than the melting point of the sheath of a fiber with an adhesive portion.

23. A method for manufacturing a nonwoven fabric as described in claim 20 or claim 21, wherein, The aforementioned fiber with an adhesive portion is an adhesive core-sheath type composite fiber.

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