Nonwoven fabric and its manufacturing method, and solid electrolyte sheet

Abstract

To provide a nonwoven fabric in which constituting fibers are short fibers and the constituting fibers are bonded to each other and which has low basis weight and high air permeability.SOLUTION: The applicant of the present application provides a nonwoven fabric in which constituting fibers are short fibers and the constituting fibers are bonded to each other by adopting a nonwoven fabric manufacturing method having a step according to the present invention to obtain the nonwoven fabric by bonding the constituent fibers to each other in a fiber layer on a base material and subsequently peeling off the bonded fibers from the base material. The nonwoven fabric having low basis weight less than 5 g / m2 and air permeability exceeding 1000 cm3 / cm2 / s is provided in an embodiment allowing the nonwoven fabric to be independently treated.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a non-woven fabric, a method for manufacturing the same, and a solid electrolyte sheet in which solid electrolyte particles are supported on the non-woven fabric.

Background Art

[0002] In recent years, non-woven fabrics have been used in various industrial applications, such as separators for electrochemical elements such as capacitors and primary / secondary batteries, support members for separators, particle carriers in sheets on which particles are supported, prepregs, gas filters and liquid filters, medical applications such as base materials for sticking drugs and masks, buffer materials, sealing materials, liquid absorbing materials, interior surface materials, cell culture base materials and cell separation members, conductive members and insulating materials, heat dissipation members and heat insulating materials, clothing materials such as linings and waddings, or as supports for liquid separation membranes, gas separation membranes, medical materials, ion exchange membranes and dialysis membranes, water electrolysis membranes, polymer electrolyte membranes for fuel cells, solid electrolyte sheets, etc.

[0003] As a specific example of such a non-woven fabric, Japanese Patent Application Laid-Open No. 2021-028869 (Patent Document 1) discloses a non-woven fabric formed by papermaking short fibers by a wet method and fiber-bonding the constituent fibers to each other. In the invention of Patent Document 1, it has been found that a fiber aggregate (non-woven fabric) with weak strength is likely to be severely damaged during handling or in the manufacturing process of a solid battery, and the solid electrolyte particles are likely to fall off. To solve this problem, the basis weight (unit: g / m ,

[0004] , , , , , , ) per unit area has a tensile strength (unit: N / 50 mm) value greater than 0.5. In Example 1 of Patent Document 1, a non-woven fabric with a basis weight (weighing) of 5 g / m 2 and an air permeability of 600 cm 3 / cm 2 / s was manufactured.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] In recent years, there has been a demand for non-woven fabrics with a lower basis weight and higher air permeability so that non-woven fabrics that can be used in more various industrial applications can be provided. For example, for all-solid-state batteries, improvement of energy density and reduction of resistance are required. Therefore, as a support for holding a solid electrolyte in an all-solid-state battery, a non-woven fabric with a lower basis weight so that the resistance can be further reduced and a larger void and higher air permeability so that more solid electrolyte particles can be packed in the space of the support are required to be utilized.

[0006] Therefore, the present invention aims to provide a non-woven fabric with a lower basis weight and higher air permeability than non-woven fabrics (non-woven fabrics in which constituent fibers are short fibers and the constituent fibers are fiber-bonded to each other) disclosed in prior arts such as Patent Document 1.

MEANS FOR SOLVING THE PROBLEMS

[0007] The present invention is “(Claim 1) A non-woven fabric in which constituent fibers are short fibers, The aforementioned nonwoven fabric contains, as constituent fibers, partially fused, heat-fusible fibers which are short fibers with a tensile strength of 4.5 cN / dtex or more. wherein the constituent fibers are Adhesion by the aforementioned heat-fusible fibers such that, the basis weight is less than 5 g / m 2 and the air permeability is higher than 1000 cm 3 / cm 2 / s Furthermore, the apparent density is 0.13 g / cm³. 3 The following is: non-woven fabric. (Claim 2) The non-woven fabric according to Claim 1, wherein the air permeability is 1440 cm 3 / cm 2 / s or more. (Claim 3) The non-woven fabric according to Claim 2, wherein the constituent fibers include core-sheath type adhesive short fibers having a fiber diameter of 7 μm or more. (Claim 4) The nonwoven fabric according to claim 3, wherein the constituent fibers consist only of core-sheath type adhesive short fibers with a fiber diameter of 7 μm or more. (Claim 5) The nonwoven fabric according to claim 4, wherein the sheath component of the core-sheath type adhesive short fiber is a polyolefin resin. (Claim 6) A solid electrolyte sheet comprising a nonwoven fabric according to any one of claims 1 to 5, on which solid electrolyte particles are supported. (Claim 7) Nonwoven fabric according to claim 1 A method for manufacturing, Process (1) It contains partially fused, heat-fusible fibers, which are short fibers with a tensile strength of 4.5 cN / dtex or higher. A process to prepare a dispersion in which short fibers are dispersed, Step (2) Step of preparing the base material, Step (3) Step of forming a laminate on the substrate by forming the dispersion liquid onto the main surface of the substrate, wherein the laminate has a fiber layer containing the short fibers. Step (4) Step to remove the dispersion medium contained in the laminate, Step (5) By heating the laminate, the constituent fibers of the fiber layer are separated Adhesion by the aforementioned heat-fusible fibers Then, a process of allowing it to cool and / or cooling, Step (6) Step of peeling the fiber layer from the laminate after cooling and / or cooling, and obtaining the peeled fiber layer as a nonwoven fabric. Equipped with, Nonwoven fabric according to claim 1 The manufacturing method. That is the case. [Effects of the Invention]

[0008] The applicant for this application has provided a nonwoven fabric in which the constituent fibers are short fibers and the constituent fibers are bonded together, with a basis weight of 5 g / m². 2 Less than 1000cm and light with breathability of 1000cm 3 / cm 2 We have succeeded in providing a nonwoven fabric with a higher air permeability of 1440 cm² in a manner that allows for independent handling. In particular, the applicant has succeeded in providing a nonwoven fabric with an air permeability of 1440 cm². 3 / cm 2 We have succeeded in providing nonwoven fabrics with a thickness of / s or higher in a form that can be handled independently.

[0009] Furthermore, the applicant could also provide the aforementioned nonwoven fabric by having the constituent fibers include core-sheath type adhesive short fibers with a fiber diameter of 7 μm or more, and more preferably by having the constituent fibers consist only of core-sheath type adhesive short fibers with a fiber diameter of 7 μm or more.

[0010] Furthermore, we were also able to provide the aforementioned nonwoven fabric in which the sheath component of the core-sheath type adhesive short fiber is a polyolefin resin.

[0011] Furthermore, the nonwoven fabric according to the present invention has a low basis weight and a highly permeable structure (in other words, a structure having voids suitable for supporting a sufficient amount of solid electrolyte particles, etc.). Therefore, by using the nonwoven fabric according to the present invention, it is possible to provide a particle-supported sheet in which particles are supported on the nonwoven fabric in the intended manner, such as being able to support a large amount of particles between the constituent fibers of the nonwoven fabric and on the surface of the constituent fibers. Therefore, by supporting solid electrolyte particles on the nonwoven fabric according to the present invention, it is possible to provide a solid electrolyte sheet in which solid electrolyte particles are supported on the nonwoven fabric in the intended manner, such as being able to support a large amount of solid electrolyte particles.

[0012] Unlike the method for manufacturing a nonwoven fabric disclosed in Patent Document 1, the method for manufacturing a nonwoven fabric according to the present invention includes a step of forming a fiber layer on a substrate by papermaking the constituent fibers (short fibers) of the nonwoven fabric onto the substrate, then subjecting the substrate and the fiber layer to a heating step, and then allowing it to cool and / or refrigerate. Therefore, by going through this heating step, the constituent fibers of the fiber layer are bonded together, preventing the structure of the papermade fiber layer from unintentionally collapsing, and thus a strong fiber layer with the constituent fibers bonded together can be formed on the substrate.

[0013] As a result, even when a fiber layer with a light basis weight and high breathability is formed, it becomes possible to peel off the fiber layer from the base material after a heating process, and the peeled fiber layer can be obtained as a nonwoven fabric with a low basis weight and high breathability that can be handled on its own. [Modes for carrying out the invention]

[0014] In the present invention, various configurations can be appropriately selected, such as the following configuration. Unless otherwise specified, the various measurements described in the present invention were performed under atmospheric pressure. Furthermore, the measurements were performed under a temperature of 25°C. Unless otherwise specified, the various measurement results described in the present invention were obtained by measuring to a value one decimal place smaller than the desired value, and then rounding that value to obtain the desired value. For example, if the desired value is to be expressed to one decimal place, the value was measured to two decimal places, and the obtained value to the second decimal place was rounded to obtain the value to one decimal place, and this value was used as the desired value.

[0015] Furthermore, the upper and lower limits listed below can be combined as desired to define a range of acceptable values.

[0016] The nonwoven fabric according to the present invention contains short fibers as its constituent fibers, and these short fibers can form the backbone of the nonwoven fabric. In the present invention, short fibers refer to fibers that have a specific length, which are prepared by cutting, and not fibers that have multiple fibers generated by splitting in the middle of the fiber. Examples of fibers that have multiple fibers generated by splitting in the middle of the fiber include fibril fibers and pulp fibers. Examples of fibers that do not have a specific length and are prepared by cutting include fibers with a continuous length that are spun using direct spinning methods such as electrospinning, meltblowing, or spunbonding. The short fibers constituting the nonwoven fabric may have crimp.

[0017] Short fibers include, for example, polyolefin resins (e.g., polyethylene, polypropylene, polymethylpentene, polyolefin resins with a structure in which part of the hydrocarbon is replaced with a cyano group or a halogen such as fluorine or chlorine), styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (e.g., polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, all aromatic polyester resins, etc.), polyimide resins, poly The nonwoven fabric can be constructed using known resins such as amide-imide resins, polyamide resins (e.g., aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having nitrile groups (e.g., polyacrylonitrile), urethane resins, epoxy resins, polysulfone resins (e.g., polysulfone, polyethersulfone, etc.), fluororesins (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, and acrylic resins (e.g., polyacrylonitrile resins copolymerized with acrylic acid esters or methacrylic acid esters, modacrylic resins copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.). In particular, it is preferable that the short fibers are made of polyolefin resins so that a nonwoven fabric with excellent chemical resistance (acid resistance, alkali resistance, organic solvent resistance, etc.) can be used for various industrial applications.

[0018] These resins may consist of either linear or branched polymers, and may be block copolymers or random copolymers. Furthermore, there are no particular limitations on the three-dimensional structure or crystalline properties of the resins. They may also be mixtures of multiple resin components.

[0019] The short fibers may be composed of one type of resin or multiple types of resins. Short fibers composed of multiple types of resins can be composite fibers, such as core-sheath type, sea-island type, side-by-side type, orange type, or bimetal type.

[0020] When the short fibers are heat-fusible fibers, it is preferable to provide a nonwoven fabric with high strength, even if it has a low basis weight and high breathability, by heat-fusing the constituent fibers of the nonwoven fabric together. For this reason, it is preferable for the nonwoven fabric to contain heat-fusible short fibers as constituent fibers, and it is even more preferable for the constituent fibers of the nonwoven fabric to consist only of heat-fusible short fibers. Such heat-fusible short fibers may be of the fully fusible type, or of the partially fusible type, such as the composite fibers described above. However, since the fiber shape can be maintained even after heat fusion, thereby further imparting strength and morphological stability to the nonwoven fabric, it is preferable for the heat-fusible short fibers to be of the partially fusible type, such as a core-sheath type or side-by-side type, which have a portion with a higher melting point than the heat-fusible component. In particular, it is preferable to use core-sheath type heat-fusible short fibers (core-sheath type adhesive short fibers, especially core-sheath type adhesive short fibers in which the sheath portion is made of polyolefin resin) so that a high-strength nonwoven fabric can be provided in which the constituent fibers are integrated at the intersections by the sheath component. Furthermore, by employing core-sheath type adhesive short fibers, it is preferable to provide a particle-supported sheet in which particles are supported on the sheath component of the core-sheath type adhesive short fibers constituting the nonwoven fabric. From this viewpoint, it is preferable that the constituent fibers of the nonwoven fabric consist only of core-sheath type adhesive short fibers (especially core-sheath type adhesive short fibers in which the sheath portion is made of polyolefin resin).

[0021] In particular, polyolefin resins are more easily softened than other resins. Therefore, when compounding a nonwoven fabric in which the sheath component of core-sheath type adhesive short fibers is polyolefin resin with solid electrolyte particles, it is preferable that the core-sheath type adhesive short fibers are easily deformed to an appropriate degree, thereby providing a nonwoven fabric that can easily hold particles such as solid electrolyte particles.

[0022] Furthermore, short fibers may have cross-sectional shapes other than those with a roughly circular or elliptical cross-section. These irregular cross-sectional shapes may include hollow shapes, polygonal shapes such as triangular shapes, alphabetic shapes such as Y-shapes, irregular shapes, multi-lobed shapes, symbolic shapes such as asterisks, or shapes formed by combining multiple such shapes.

[0023] The fineness, fiber diameter, and fiber length of the short fibers are not particularly limited and can be adjusted as appropriate. The fineness can be 10 dtex or less, 5 dtex or less, or 1 dtex or less. The lower limit of the fineness can be adjusted as appropriate, but it is practical to be 0.01 dtex or more. The fiber diameter of the short fibers can be adjusted as appropriate, but can be 0.1 to 30 μm, 3 to 20 μm, or 5 to 15 μm. In particular, by using short fibers with a fiber diameter of 7 μm or more (especially core-sheath type adhesive short fibers), it is possible to provide a nonwoven fabric with high strength even with a low basis weight and high breathability structure. From this viewpoint, it is preferable that the constituent fibers of the nonwoven fabric consist only of core-sheath type adhesive short fibers with a fiber diameter of 7 μm or more (especially core-sheath type adhesive short fibers made of polyolefin resin).

[0024] Furthermore, if the nonwoven fabric contains core-sheath type adhesive short fibers with a fiber diameter of 7 μm or more as constituent fibers, the number of constituent fibers can be reduced in nonwoven fabrics of the same basis weight. This reduces the areas with small pore diameters, making it easier for solid electrolyte particles and the like to enter the interior, and it is preferable to provide a nonwoven fabric with a structure that has fewer defects and voids after filling.

[0025] The fiber length can be 0.1 to 20 mm, 0.5 to 15 mm, or 1 to 10 mm. Note that "fiber length" refers to the value measured according to JIS L1015 (2010), 8.4.1c) Direct Method (Method C).

[0026] The Young's modulus of the short fibers can be adjusted as appropriate. However, to prevent the fibers from being crushed too much during particle packing, making it difficult to provide a low-resistance solid electrolyte membrane, it is preferable to use short fibers with a Young's modulus of 10 cN / dtex (decitex) or higher, preferably 20 cN / dtex (decitex) or higher, preferably 30 cN / dtex (decitex) or higher, and preferably 40 cN / dtex (decitex) or higher. There is no particular upper limit to the Young's modulus, but values ​​of 100 cN / dtex or less, 90 cN / dtex or less, and 80 cN / dtex or less are practical.

[0027] The tensile strength of the short fibers can be adjusted as appropriate. However, to provide a nonwoven fabric made of short fibers that is strong enough to be handled on its own, even with a low basis weight and high breathability, it is preferable to use short fibers with a tensile strength of 4.5 cN / dtex or higher. A tensile strength of 5.0 cN / dtex or higher is even more preferable. There is no particular upper limit to the tensile strength, but 50 cN / dtex or less is practical. In this invention, "tensile strength" refers to the value measured according to JIS L1015 (chemical fiber short test method, constant-speed tension type).

[0028] Furthermore, it is preferable that the nonwoven fabric contains, as short fibers, partially fused heat-fusible fibers having the tensile strength (particularly core-sheath type adhesive short fibers made of polyolefin resin). By bonding and integrating the constituent fibers of the nonwoven fabric with these partially fused heat-fusible fibers having the tensile strength, it is possible to provide a nonwoven fabric that is strong enough to be handled independently, even if it has a low basis weight and high breathability. From this viewpoint, it is preferable that the constituent fibers of the nonwoven fabric consist only of partially fused heat-fusible fibers having the tensile strength (particularly core-sheath type adhesive short fibers with a sheath portion made of polyolefin resin). In particular, it is preferable that the constituent fibers of the nonwoven fabric consist only of core-sheath type adhesive short fibers with the tensile strength, where the core and sheath portions are made of polyolefin resin.

[0029] The nonwoven fabric according to the present invention is composed of short fibers aggregated together. Such a nonwoven fabric can be prepared, for example, from a fiber web prepared by a dry method in which a group of fibers containing short fibers are subjected to a carding device or an air-laying device to entangle the fibers, or by a wet method in which a group of fibers containing short fibers is dispersed in a dispersion medium and formed into a sheet.

[0030] Nonwoven fabrics can be prepared by entangling and / or integrating the fibers of a fiber web. In addition to methods such as subjecting the fiber web to heat treatment to bond and integrate the constituent fibers with the heat-fusible components contained in the fibers of the fiber web (e.g., the heat-fusible components of heat-fusible fibers), or integrating the constituent fibers with a binder resin, methods such as entanglement using needles or water flow may also be used.

[0031] The heat treatment method can be selected as appropriate, but for example, methods such as heating or heating and pressurizing with a roll, heating by subjecting to a heating device such as an oven dryer, far-infrared heater, dry heat dryer, or hot air dryer, or heating the contained resin by irradiating it with infrared rays under no pressure can be used.

[0032] The thickness of the nonwoven fabric can be adjusted as appropriate. The thickness can be 3 to 60 μm, 5 to 50 μm, or 7 to 40 μm. In the present invention, thickness refers to the length in the vertical direction when a compressive load of 160 kPa is applied perpendicular to the main surface.

[0033] The nonwoven fabric according to the present invention has a basis weight of 5 g / m². 2 It is characterized by being less than 4.4 g / m². 2 It can be less than 4.0 g / m 2 It can be as follows, 3.5g / m 2 It can be as follows: 3.0g / m 2 It can be as follows: 2.5g / m 2 It can be less than 2.0 g / m 2 It can be as follows: 1.5g / m 2The following is possible. The lower limit is 0 g / m 2 It can be made heavier and adjusted as needed, but 1.0g / m 2 The above is the most realistic explanation. In the present invention, basis refers to the area of ​​the largest surface (main surface) of the object to be measured, measured over 1 m². 2 It refers to the mass per unit area.

[0034] The nonwoven fabric according to the present invention has an air permeability of 1000 cm². 3 / cm 2 It is characterized by having a higher air per s² rating. Its air per s² rating is 1100 cm². 3 / cm 2 It can be more than / s, and 1200cm 3 / cm 2 It can be more than / s, and 1300cm 3 / cm 2 It can be more than / s, and 1400cm 3 / cm 2 It can be more than / s, 1440cm 3 / cm 2 It can be more than / s. The upper limit can be adjusted as needed, but 10,000 cm 3 / cm 2 It is more realistic to keep it below / s.

[0035] In the present invention, air permeability refers to the measurement value obtained by the method specified in JIS L1096:2010 (8.(26).1 Method A (Fragile Method)). When measuring the air permeability of a sample using this method, if the air permeability is too high to measure, the air permeability of a sample made by stacking a specific number of the sample is measured, and the measured air permeability value is multiplied by the number of stacked sample materials to obtain the air permeability per sheet. For example, the air permeability of a nonwoven fabric stacked with four sheets is 360 cm². 3 / cm 2 If the value is / s, the breathability of one sheet of nonwoven fabric is 1440 cm². 3 / cm 2 It is assumed to be / s.

[0036] The porosity of the nonwoven fabric is adjusted as appropriate to realize a nonwoven fabric having the air permeability described in the present invention. However, nonwoven fabrics with a higher porosity (unit: %) tend to satisfy the air permeability defined in the present invention, so it is preferable that the porosity is higher than 60%, preferably 70% or more, and preferably 80% or more. The upper limit is adjusted as appropriate, but it is preferable that it be 98% or less, and preferably 95% or less, so that the nonwoven fabric is of high strength. Note that "porosity" refers to the value obtained by the following formula. P = [1 - M / (T × d)] × 100 Here, M is the basis weight (unit: g / m²) of the material being measured, such as nonwoven fabric or fiber web. 2 ), T is the thickness of the object being measured (unit: μm), and d is the average density of the various organic resins that make up the object being measured (unit: g / cm³). 3 These represent the following meanings, respectively.

[0037] Also, the apparent density of the nonwoven fabric (g / cm³) 3 ) is the basis weight (g / m²) of the nonwoven fabric. 2 The apparent density of the nonwoven fabric (g / cm³) can be calculated by dividing it by the thickness of the nonwoven fabric (μm). 3 The lower limit of ) can be adjusted as appropriate, but to provide a highly breathable nonwoven fabric, it is set at 0.08 (g / cm³). 3 Preferably, it should be 0.09 (g / cm³) or more. 3 Preferably, it should be 0.1 (g / cm³) or more, and 0.1 (g / cm³) 3 It is preferable that the apparent density of the nonwoven fabric (g / cm³) is greater than or equal to ). 3 The upper limit of ) can be adjusted as appropriate, but to provide a nonwoven fabric with high strength, it is set at 0.70 (g / cm³). 3 Preferably, it should be 0.50 (g / cm³) or less. 3 Preferably, it should be 0.40 (g / cm³) or less. 3 Preferably, it is less than or equal to the following:

[0038] The tensile strength (unit: N / 50mm) and tensile elongation (unit: %) of the nonwoven fabric should be adjusted as appropriate to achieve a nonwoven fabric that can be handled independently. The tensile strength is preferably 1 N / 50mm or more, and preferably 3 N / 50mm or more. The tensile elongation is preferably 1% or more, preferably 3% or more, preferably 6% or more, and preferably 7% or more.

[0039] These "tensile strength" and "tensile elongation" can be measured by subjecting the object to the method described below. (1) A test specimen (shape: rectangular, length: 200 mm, width: 50 mm) was taken from the object to be measured, with the machine direction (direction of flow during manufacturing, referred to as MD) and the length direction aligned. (2) The collected test specimens were subjected to a constant-speed elongation tensile testing machine (Orientec Co., Ltd., Tensilon, initial gripping distance: 100 mm, tensile speed: 300 mm / min), and the tensile strength in the MD direction (N / 50 mm) was determined from the strength obtained when the specimen was pulled until it broke. (3) The tensile elongation (%) of the specimen in the MD direction was calculated by substituting the length of the gripping distance (mm) at the maximum load of the measured specimen, when the specimen was pulled until it fractured, into the following formula. a = {(bc) / c} × 100 a: Tensile elongation (%) b: Grip spacing at maximum load (mm) c: Initial gripping interval (100 mm)

[0040] Furthermore, by subjecting a test specimen (shape: rectangular, length: 200 mm, width: 50 mm) taken from the object to be measured, such that the direction perpendicular to the machine direction (referred to as CMD) coincides with the length direction, to the above-described process (2) to (3), the tensile strength (N / 50 mm) and tensile elongation (%) in the CMD direction can be obtained.

[0041] In addition to the particles relating to the present invention, the nonwoven fabric may also contain additives such as flame retardants, fragrances, pigments, antibacterial agents, antifungal agents, photocatalytic particles, emulsifiers, dispersants, surfactants, and thickeners. These additives may be incorporated by being kneaded into the constituent fibers of the nonwoven fabric, or by being provided with a binder containing the additives.

[0042] The nonwoven fabric according to the present invention can support particles between its constituent fibers and on the surface of the constituent fibers. The type of particles and the amount of particles supported are appropriately adjusted depending on the application of the particle-supported sheet formed by supporting particles on the nonwoven fabric. Examples of particles that can be used include graphite, ion exchange resin, solid electrolyte particles, polymer solid electrolytes, inorganic particles, metal particles, and polymer particles. By using the nonwoven fabric according to the present invention, it is possible to provide a particle-supported sheet in which particles are supported on the nonwoven fabric in an intended manner, such as by enabling the support of a large amount of particles between the constituent fibers and on the surface of the constituent fibers of the nonwoven fabric. In particular, by using solid electrolyte particles as the particles, it is possible to provide a solid electrolyte sheet in which solid electrolyte particles are supported on the nonwoven fabric.

[0043] Next, the method for manufacturing the nonwoven fabric of the present invention will be described. Note that explanations of points that are the same as those described above will be omitted. The method for manufacturing the nonwoven fabric according to the present invention can be appropriately selected, but as an example, Step (1) A core-sheath type adhesive short fiber is used as the short fiber (core: has a higher softening temperature or melting point than the resin contained in the sheath, sheath: has a lower softening temperature or melting point than the resin contained in the core), and the short fiber is dispersed in a dispersion medium to prepare a dispersion. Step (2) A step of laying a separately prepared substrate on a papermaking mesh, and forming a laminate on the main surface of the substrate by forming core-sheath type adhesive short fibers contained in the dispersion liquid, thereby forming a laminate on the separately prepared substrate having a fiber layer in which core-sheath type adhesive short fibers are aggregated together. Step (3) Step to remove the dispersion medium contained in the laminate, Step (4) The laminate is subjected to a heating device to soften or melt the sheath component of the core-sheath type adhesive short fibers contained in the fiber layer, thereby bonding and integrating the constituent fibers of the fiber layer, and then the laminate is allowed to cool and / or cooled. Step (5) After the laminate has been subjected to a heating device and cooled, the fiber layer in which the core-sheath type adhesive short fibers are bonded is peeled off, and the peeled fiber layer is obtained as a nonwoven fabric. This can be a method for manufacturing nonwoven fabrics that includes the following features:

[0044] The applicant has adopted a method for manufacturing nonwoven fabric comprising the steps described above, thereby achieving a basis weight of 5 g / m² for the present invention. 2 It is less than 1000 cm and the breathability is 1000 cm 3 / cm 2 We have found that we can provide a nonwoven fabric with a higher coefficient of friction than / s. However, as long as the manufacturing method disclosed in Patent Document 1 is adopted, that is, as long as the manufacturing method for nonwoven fabric is adopted which does not include steps (3) to (5) of the present invention, in which the constituent fibers of the fiber layer are bonded to the substrate and then peeled off from the substrate to obtain the nonwoven fabric, even if one attempts to manufacture the nonwoven fabric according to the present invention, the nonwoven fabric will be damaged in the manufacturing process and it will not be possible to manufacture a nonwoven fabric that can be handled on its own.

[0045] Let's explain step (1). The type of dispersion medium used to disperse the short fibers can be adjusted as appropriate, and water can be used. The dispersion medium may contain additives such as surfactants and viscous agents, but in order to produce a nonwoven fabric in which the short fibers aggregate to form a sheet shape, which has a low basis weight and good breathability, the dispersion medium can be one which does not contain additives other than short fibers, and white water containing surfactants and viscous agents can be used. The amount of short fibers dispersed in the dispersion medium can be adjusted as appropriate.

[0046] Step (2) will be explained. The type of base material to be prepared can be selected as appropriate, including the papermaking mesh provided by the papermaking machine, separately prepared mesh, woven fabric, nonwoven fabric (such as PET nonwoven fabric), etc. It is preferable to use a base material that is permeable to water. To efficiently form fibers on the base material, it is preferable to use a nonwoven fabric with a pore diameter smaller than the fiber length of the short fibers contained in the dispersion medium.

[0047] Usable resins include, for example, polyolefin resins (e.g., polyethylene, polypropylene, polymethylpentene, and polyolefin resins with structures in which some hydrocarbons are replaced with cyano groups or halogens such as fluorine or chlorine), styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (e.g., polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, all aromatic polyester resins, etc.), and polyimide resins. It can be constructed using known resins such as resins, polyamide-imide resins, polyamide resins (e.g., aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having nitrile groups (e.g., polyacrylonitrile, etc.), urethane resins, epoxy resins, polysulfone resins (e.g., polysulfone, polyethersulfone, etc.), fluorine resins (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, and acrylic resins (e.g., polyacrylonitrile resins copolymerized with acrylic acid esters or methacrylic acid esters, modacrylic resins copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.).

[0048] The composition of the base material is preferably such that its melting point is higher than the heat bonding temperature of the short fibers and it does not easily adhere to the heat bonding resin, in order to facilitate the peeling of the fiber layer made of core-sheath type adhesive short fibers. Furthermore, the composition is appropriately adjusted to facilitate the peeling of the fiber layer made of core-sheath type adhesive short fibers from the base material. As an example, a nonwoven fabric can be used in which a fiber web containing undrawn fibers in its constituent fibers is subjected to a heat-compression bonding process, resulting in the constituent fibers being heat-compressed together without melting. Moreover, to prevent the binder from unintentionally adhering to the fiber layer, it is preferable to use a base material in which the constituent fibers are bonded together by fiber bonding or heat-compression bonding, rather than a base material in which the constituent fibers are bonded together by a binder. Finally, it is preferable to use a base material with a strength of 5N / 5cm or more to prevent damage to the base material when peeling the fiber layer made of core-sheath type adhesive short fibers from the base material.

[0049] As a specific example of the base material mentioned above, a PET nonwoven fabric prepared by subjecting a fiber web containing undrawn PET fibers to a heat-sealing process can be used.

[0050] Furthermore, it is preferable to use a wet-laid nonwoven fabric as the base material to prevent the nonwoven fabric of the present invention from being unobtainable due to an uneven distribution of fibers in the base material resulting in an uneven distribution of fibers in the resulting fiber layer. The air permeability of the nonwoven fabric used as the base material should be 200 cm². 3 / cm 2 It is preferable that the value is less than or equal to / s. As a material that satisfies the above-mentioned viewpoint, wet-type PET nonwoven fabric is preferred.

[0051] Furthermore, to enable the short fibers contained in the dispersion to be formed onto the main surface of a separately prepared substrate, a suction device for removing the dispersion medium may be provided on the main surface of the substrate opposite to the main surface on which the short fibers are formed. The amount of dispersion liquid to be printed onto the main surface of the separately prepared substrate is 5g / m². 2 Adjust as needed to enable the production of nonwoven fabrics of less than [amount missing].

[0052] Step (3) will be explained. The method for removing the dispersion medium contained in the laminate can be appropriately selected. For example, the dispersion medium can be evaporated and removed by heating it in a heating device such as an oven dryer, far-infrared heater, dry heat dryer, or hot air dryer, or by letting it stand in a room temperature atmosphere or a reduced pressure atmosphere. The heating temperature when removing the dispersion medium should be at a temperature at which the dispersion medium can volatilize, and the upper limit of the heating temperature should be adjusted (for example, to a temperature below the softening temperature or melting point of the resin contained in the sheath) so that the shape and function of the components constituting the nonwoven fabric do not unintentionally deteriorate.

[0053] Step (4) will be explained. As the heating device, the heating device mentioned in step (3) can be used. The heating temperature is such that the sheath component of the core-sheath type adhesive short fibers is softened or melted, allowing the constituent fibers of the fiber layer to be bonded together, while the upper limit of the heating temperature is adjusted so that the shape and function of the components constituting the nonwoven fabric do not unintentionally deteriorate. Specifically, the heating temperature is preferably within a temperature range of 50°C or less above the softening temperature or melting point of the resin to be softened or melted, and preferably within a temperature range of 30°C or less.

[0054] The heated laminate is cooled by letting it stand at room temperature or by using a cooling device. Cooling allows for the production of a nonwoven fabric in which the short fibers are not only aggregated but also bonded together.

[0055] Step (5) will be explained. By peeling off the fiber layer, which consists of core-sheath type adhesive short fibers, from the laminate after it has been subjected to a heating device and cooled, the peeled fiber layer can be made into a nonwoven fabric.

[0056] The nonwoven fabric according to the present invention can be manufactured by the above manufacturing method.

[0057] Furthermore, if the nonwoven fabric contains polyolefin resin fibers as short fibers (such as core-sheath type adhesive short fibers with a sheath made of polyolefin resin), the nonwoven fabric can be suitably used as a support for a solid electrolyte. However, in order to efficiently manufacture a nonwoven fabric containing polyolefin resin short fibers, an oil agent may be applied to the short fibers, or an activator may be added to the white water used to form the fabric on the substrate. In this case, with the conventional method of manufacturing nonwoven fabrics, the surface of the short fibers becomes slippery, and a nonwoven fabric that satisfies the configuration of the present invention cannot be manufactured. However, by adopting the manufacturing method of nonwoven fabrics according to the present invention, a nonwoven fabric that satisfies the configuration of the present invention can be manufactured even under the above conditions.

[0058] The above-described method for manufacturing nonwoven fabrics may include various secondary processes, such as laminating other porous materials, films, foams, and other constituent materials, and processing the nonwoven fabric by punching out shapes according to its intended use and application. Furthermore, the method may also include various secondary processes, such as adjusting the nonwoven fabric's physical properties, including thickness and surface smoothness, using a calender or similar device.

[0059] A particle-supported sheet can be manufactured by supporting particles on a nonwoven fabric produced in the manner described above. The method of supporting particles on the nonwoven fabric can be adjusted as appropriate, but possible methods include simply attaching the particles to the nonwoven fabric, bonding and fixing the particles to the nonwoven fabric with a binder, heating the particles in contact with the constituent fibers of the nonwoven fabric to melt the resin constituting the surface of the constituent fibers (for example, the resin constituting the sheath portion in core-sheath type adhesive short fibers) and fixing the particles to the surface of the constituent fibers with the molten resin, or contacting heated particles with the constituent fibers of the nonwoven fabric to melt the resin constituting the surface of the constituent fibers and fixing the particles to the surface of the constituent fibers with the molten resin. [Examples]

[0060] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0061] (Short fibers used) A core-sheath type adhesive short fiber A was prepared, consisting of a polypropylene core with a melting point of 168°C and a high-density polyethylene sheath with a melting point of 135°C, with a core area to sheath area ratio of 60%:40% in the fiber cross-section (fineness: 0.8 decitex, fiber diameter: 11 μm, fiber length: 5 mm, tensile strength: 6 cN / dtex, Young's modulus: 40 cN / dtex). Furthermore, a core-sheath type adhesive short fiber B (fineness: 0.4 decitex, fiber diameter: 7 μm, fiber length: 5 mm, tensile strength: 6 cN / dtex, Young's modulus: 77 cN / dtex) was prepared, in which the core is composed of polypropylene with a melting point of 168°C and the sheath is composed of high-density polyethylene with a melting point of 135°C, with a ratio of core area to sheath area in the fiber cross-section of 60%:40%.

[0062] (Comparative Example 1) A dispersion was prepared by dispersing core-sheath type adhesive short fibers A in water containing an activator. Then, the core-sheath type adhesive short fibers A contained in the dispersion were directly applied to the main surface of the papermaking mesh of a 200 mm x 250 mm square papermaking machine. As a result, a laminate with a fiber layer made of core-sheath type adhesive short fibers A was formed on the papermaking mesh. At this time, the basis weight of the fiber layer was 4.0 g / m² when dry. 2 The amount of dough being pulped was adjusted to achieve this result. Next, we attempted to prepare a nonwoven fabric by peeling the fiber layer from the laminate. However, the fiber layer was damaged during this process, making it impossible to obtain a nonwoven fabric on its own.

[0063] (Example 1) A dispersion was prepared by dispersing core-sheath type adhesive short fibers A in water containing an activator. Then, a fiber web containing undrawn PET fibers, prepared separately, was subjected to a heat-sealing process on a papermaking mesh of a 200mm x 250mm square papermaking machine to prepare a wet PET nonwoven fabric (basis weight: 6g / m²). 2 Thickness: 10 μm, Air permeability: 140 cm² 3 / cm 2A wet-type PET nonwoven fabric (hereinafter abbreviated as / s) was laid out, and core-sheath type adhesive short fibers A contained in the dispersion were formed on the main surface of the wet-type PET nonwoven fabric. This formed a laminate on the wet-type PET nonwoven fabric with a fiber layer made of core-sheath type adhesive short fibers A. At this time, the basis weight of the fiber layer was 4.0 g / m² when dry. 2 The amount of dough being pulped was adjusted to achieve this result. The laminate was then removed from the papermaking mesh and subjected to an oven dryer heated to 140°C. This removed the dispersion medium and melted the sheath component of the core-sheath type adhesive short fibers A, causing the core-sheath type adhesive short fibers A to bond together. After that, it was cooled by air cooling. Then, the fiber layer is peeled off from the wet PET nonwoven fabric, resulting in a basis weight of 4.0 g / m². 2 A nonwoven fabric was obtained on its own.

[0064] (Example 2) The weight of the fiber layer is 2.0 g / m² when dry. 2 Except for adjusting the amount to be produced so that the basis weight was 2.0 g / m², the procedure was the same as in Example 1. 2 A nonwoven fabric was obtained on its own.

[0065] (Examples 3-5) A dispersion was prepared by dispersing core-sheath type adhesive short fibers B in water containing an activator. Then, a separately prepared wet PET nonwoven fabric (basis weight: 6g / m²) was placed on the papermaking mesh of a 200mm x 250mm rectangular papermaking machine. 2 A sheet of wet PET nonwoven fabric (thickness: 10 μm) was laid down, and core-sheath type adhesive short fibers B contained in the dispersion were formed on the main surface of the wet PET nonwoven fabric. This formed a laminate on the wet PET nonwoven fabric with a fiber layer made of core-sheath type adhesive short fibers B. In this case, in Example 3, the basis weight of the fiber layer was 1.5 g / m² when dry. 2 The amount of paper produced was adjusted so that the basis weight of the fiber layer in Example 4 was 2.0 g / m² when dry. 2 The amount of paper produced was adjusted so that the basis weight of the fiber layer in Example 5 was 3.0 g / m² when dry. 2 The amount of dough being pulped was adjusted to achieve this result. The laminate was then removed from the papermaking mesh and subjected to an oven dryer heated to 140°C. This removed the dispersion medium and melted the sheath component of the core-sheath type adhesive short fibers B, causing the core-sheath type adhesive short fibers B to bond together. After that, it was cooled by air cooling. Then, the fiber layer was peeled off from the wet PET nonwoven fabric, resulting in a basis weight of 1.5 g / m² in Example 3. 2 In Example 4, the nonwoven fabric had a basis weight of 2.0 g / m². 2 In Example 5, the nonwoven fabric had a basis weight of 3.0 g / m². 2 Each of these nonwoven fabrics was obtained individually.

[0066] The physical properties of each nonwoven fabric manufactured as described above are summarized in Table 1. Items that could not be measured because the nonwoven fabric could not be manufactured are indicated with a "-" in the table.

[0067] [Table 1]

[0068] When short fibers are directly printed onto the main surface of a papermaking mesh using the nonwoven fabric manufacturing method described in Patent Document 1, as in Comparative Example 1, the basis weight of the short fibers printed onto the main surface of the papermaking mesh is 5 g / m². 2 When the value was set to less than a certain level, it was not possible to manufacture nonwoven fabrics in a manner that could be handled independently.

[0069] In contrast, in Examples 1-5, short fibers are bonded together, and the basis weight is 5 g / m². 2 It is less than 1000 cm and the breathability is 1000 cm 3 / cm 2 Nonwoven fabrics with a higher / s rating (especially those with a breathability of 1440 cm²) 3 / cm 2 We were able to provide nonwoven fabrics (with a viscosity of / s or higher) in a form that allows for independent handling. [Industrial applicability]

[0070] The nonwoven fabric according to the present invention can be used in a variety of industrial applications, such as separators and separator support members for electrochemical elements such as capacitors and primary / secondary batteries, particle carriers in sheets on which particles are supported, prepregs, gas filters and liquid filters, medical applications such as adhesive base materials and masks, cushioning materials and sealing materials, liquid absorbent materials, interior surface materials, cell culture substrates and cell separation members, conductive members and insulating materials, heat dissipation members and heat insulating materials, clothing materials such as interlining and padding, or as supports for liquid separation membranes and gas separation membranes, medical materials, ion exchange membranes and dialysis membranes, water electrolysis membranes, polymer electrolyte membranes for fuel cells, and solid electrolyte sheets.

Claims

1. A nonwoven fabric whose constituent fibers are short fibers, The aforementioned nonwoven fabric contains, as constituent fibers, partially fused, heat-fusible fibers which are short fibers with a tensile strength of 4.5 cN / dtex or more. The constituent fibers are bonded together by the heat-fusible fibers, Weight: 5 g / m ２ It is less than 1000 cm², and the breathability is 1000 cm². ３ / cm ２ The density is higher than / s and the apparent density is 0.13 g / cm³ or less. Nonwoven fabric.

2. Air permeability of 1440 cm ３ / cm ２ The nonwoven fabric according to claim 1, wherein the length is / s or greater.

3. The nonwoven fabric according to claim 2, wherein the constituent fibers include core-sheath type adhesive short fibers with a fiber diameter of 7 μm or more.

4. The nonwoven fabric according to claim 3, wherein the constituent fibers consist only of core-sheath type adhesive short fibers with a fiber diameter of 7 μm or more. cloth.

5. The nonwoven fabric according to claim 4, wherein the sheath component of the core-sheath type adhesive short fiber is a polyolefin resin.

6. A solid electrolyte sheet comprising a nonwoven fabric according to any one of claims 1 to 5, on which solid electrolyte particles are supported.

7. A method for manufacturing a nonwoven fabric according to Claim 1, Step (1) A step of preparing a dispersion in which short fibers are dispersed, including partially fused, heat-fusible short fibers having a tensile strength of 4.5 cN / dtex or more. Step (2) Step of preparing the base material, Step (3) Step of forming a laminate on the substrate by forming the dispersion liquid on the main surface of the substrate, the laminate having a fiber layer containing the short fibers. Step (4) Step to remove the dispersion medium contained in the laminate, Step (5) Heating the laminate to bond the constituent fibers of the fiber layer together with the heat-fusible fibers, and then allowing it to cool and / or to cool. Step (6) Step of peeling the fiber layer from the laminate after cooling and / or cooling, and obtaining the peeled fiber layer as a nonwoven fabric, A method for producing a nonwoven fabric according to claim 1, comprising:

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