Functional nonwoven fabric and method for manufacturing the same

Abstract

Provided is a functional nonwoven fabric and a method for producing the same, which suppresses the detachment of functional particles and the reduction in air permeability of the nonwoven fabric. A functional nonwoven fabric (1) is configured by including long fibers made of a synthetic resin that have functional particles (4, 4) integrated therewith. The long fibers vary in diameter in the longitudinal direction of the fibers in a manner in which a plurality of large-diameter portions (2, 2) and small-diameter portions (3, 3) are alternately arranged. The small-diameter portions (3, 3) are monofilaments formed of the synthetic resin. At least a portion of the large-diameter portions (2, 2) includes the functional particles (4). The fiber diameter of the small-diameter portions (3, 3) is smaller than the diameter of the functional particles (4, 4) included in the large-diameter portions (2, 2).

Description

Technical Field

[0001] This invention relates to functional nonwoven fabrics containing functional particles with specified functions and methods for manufacturing the same. Background Technology

[0002] Functional nonwoven fabrics are created by loading synthetic resin fiber nonwoven fabrics with particles possessing specific functions. For example, loading nonwoven fabrics with activated carbon particles imparts deodorizing and gas adsorption functions. Depending on desired additional functions such as water retention, fluorescence, and light absorption, nonwoven fabrics are loaded with appropriate functional particles.

[0003] One method for loading functional particles onto nonwoven fabric is to impregnate the nonwoven fabric with sizing functional particles, thereby attaching the functional particles to the surface of the synthetic fibers constituting the nonwoven fabric. In this case, an adhesive may also be used to prevent the functional particles from detaching. For example, Patent Document 1 discloses a dust removal and deodorization filter technology in which a dust removal nonwoven fabric located on the upstream side of an airflow contains solid superacid particles in a layered deodorization filter. It also discloses that the solid superacid particles are dispersed in water together with a silane coupling agent to form a slurry, and the dust removal nonwoven fabric located on the upstream side is impregnated into the slurry so that the nonwoven fabric carries the solid superacid particles.

[0004] In addition, materials and raw materials with thermal expansion are sometimes used in refractory structures and the like. Functional particles with thermal expansion properties, such as graphite, expand when exposed to high temperatures. Experiments have been conducted to utilize this thermal expansion property to adjust air permeability, among other things. For example, it has been tried to create openings in the ceiling of buildings, allowing airflow under normal conditions, and then blocking or reducing the size of these openings to restrict the ceiling's air permeability when the surrounding area becomes hot due to events such as a fire.

[0005] For example, Patent Document 2 discloses a technique for embedding a cylindrical plastic composite into a ventilation hole in a fireproof eaves-type ceiling, wherein the plastic composite contains thermally expandable graphite, and discloses that if the surrounding area becomes high temperature due to fire or the like, the thermally expandable graphite contained in the plastic composite (thermally expandable component) expands, blocking the ventilation hole and restricting ventilation. Existing technical documents Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2002-331212 Patent Document 2: Japanese Patent Publication No. 2006-226050 Summary of the Invention The problem to be solved by the present invention

[0007] In conventional functional nonwoven fabrics as disclosed in Patent Document 1, the following problems are prone to occur. In some cases, adhesives are used to prevent functional particles from detaching. However, if adhesives are used to hold the functional particles, it can cause clogging of the nonwoven fabric and easily impair its breathability. This tendency to clogging becomes particularly pronounced if the diameter of the functional particles is larger than the diameter of the nonwoven fibers or the pore size.

[0008] Furthermore, in existing technologies, if a large number of functional particles are loaded onto the nonwoven fabric, these particles tend to accumulate between the nonwoven fibers, making it difficult to maintain the fabric's breathability. Additionally, in existing technologies, if a large number of functional particles are to be loaded, these particles tend to accumulate on the surface of the nonwoven fabric on the sizing side, making it difficult to evenly disperse the functional particles within the nonwoven fabric.

[0009] Furthermore, in conventional thermal expansion components as disclosed in Patent Document 2, the following problem easily occurs when it is desired to adjust the breathability. First, conventional thermally expandable components, as disclosed in Patent Document 2, are made from non-permeable raw materials. Therefore, when molding them into components, it is necessary to create holes and air channels. In the technology of Patent Document 2, the component is molded into a cylindrical shape with through holes. These holes are typically 1 millimeter to several centimeters in size, but if the holes are large, sealing the channels takes a considerable amount of time.

[0010] Furthermore, in conventional technologies for thermally expandable components, the expansion of thermally expandable graphite tends to be uneven and slow because it is incorporated into the plastic composite material. That is, even when hot air reaches the vicinity of the plastic composite material, the temperature rise of the internal parts is slower compared to the surface, as the composite material is gradually heated from the surface. Therefore, the internal parts of the plastic composite material have difficulty reaching the expansion initiation temperature, resulting in delayed expansion. Moreover, if the surface part of the plastic composite material is heated and expands, only the surface part expands; this expanded portion acts as a heat insulation layer, actually hindering the heating of the internal parts of the plastic composite material, leading to further delayed expansion.

[0011] The present invention aims to provide a functional nonwoven fabric capable of suppressing the shedding of functional particles and suppressing the reduction of air permeability of the nonwoven fabric. Another objective of the present invention is to provide a functional nonwoven fabric capable of suppressing the reduction of air permeability of the nonwoven fabric even when the amount of functional particles is increased. Furthermore, another objective of the present invention is to provide a functional nonwoven fabric capable of uniformly dispersing functional particles within the nonwoven fabric even when the amount of functional particles is increased.

[0012] Another object of the present invention is to provide a thermally expandable nonwoven fabric that is breathable and can expand more quickly using high-temperature air. Methods for solving problems

[0013] The inventors conducted in-depth research and found that if a nonwoven fabric is constructed in a manner that includes long fibers, with large-diameter and small-diameter portions alternately arranged in the long fibers, and the large-diameter portions contain functional particles, while the small-diameter portions are made into monofilaments of synthetic resin, and the fiber diameter of the small-diameter portions is less than or equal to the diameter of the functional particles contained in the large-diameter portions, then at least one of the above-mentioned problems can be solved, thereby completing the present invention.

[0014] The present invention provides a functional nonwoven fabric comprising long fibers made of synthetic resin integrally formed of functional particles having a specified function, wherein the long fibers have a diameter variation along the long side of the fiber in a manner in which multiple large-diameter portions and small-diameter portions are arranged alternately, wherein the small-diameter portions are monofilaments formed by the synthetic resin, and at least a portion of the large-diameter portions contains the functional particles, wherein the fiber diameter of the small-diameter portions is less than the diameter of the functional particles contained in the large-diameter portions (first invention).

[0015] In the first invention, it is preferred that at least a portion of the large-diameter portion is formed by solidifying a plurality of the functional particles into a rope or clump using the synthetic resin (second invention). In the second invention, it is preferred that the fiber diameter of the small-diameter portion is 1 / 100 or more of the diameter of the functional particle (third invention). Furthermore, in the third invention, it is preferred that the fiber diameter of the small-diameter portion is 100 nanometers or more and 10 micrometers or less, and the diameter of the functional particle is 300 nanometers or more and 200 micrometers or less (fourth invention). Additionally, in any one of the first to fourth inventions, it is preferred that the functional particle is a particle with thermal expansion properties (fifth invention). Furthermore, in the fifth invention, it is preferred that the functional particle is an aluminum phosphite particle (sixth invention).

[0016] In addition, the present invention provides a method for manufacturing a functional nonwoven fabric. The method for manufacturing the functional nonwoven fabric of any one of the first to sixth inventions includes the following steps: a first step, heating the synthetic resin to melt it or dissolving it in a solvent to liquefy it, thereby dispersing the functional particles into the liquefied synthetic resin; and a second step, following the first step, spinning the liquefied synthetic resin containing the functional particles using a melt-blowing method or an electrospinning method to form long fibers, and then forming a nonwoven fabric. (Seventh Invention).

[0017] In addition, the inventors conducted in-depth research and found that if a nonwoven fabric is formed by including long fibers, forming a thermally expandable nonwoven fabric in which the long fibers are arranged in a bead-like manner with a large diameter portion and a small diameter portion, and the large diameter portion contains thermally expandable functional particles, and the fiber diameter of the small diameter portion is smaller than the diameter of the functional particles of the large diameter portion, then at least one of the above-mentioned problems can be solved, thereby completing the following invention.

[0018] In the first invention, preferably, the functional particles have thermal expansion properties, the functional nonwoven fabric is a functional nonwoven fabric with thermal expansion properties, and the long fibers are configured to be arranged in a series of alternating large-diameter portions and small-diameter portions (eighth invention).

[0019] In the eighth invention, it is preferred that the functional particles are aluminum hydrogen phosphite particles (ninth invention). Furthermore, in the eighth or ninth invention, it is preferred that the large-diameter portion is rope-like or clump-like, and the functional particles are surrounded by or bonded by the synthetic resin in the form of a film, mesh, or fiber bundle, thereby becoming integrated with the large-diameter portion (tenth invention). Furthermore, in the eighth invention, it is preferable that the diameter of the fiber in the small-diameter portion is 1 / 100 or more of the diameter of the functional particle (eleventh invention). Moreover, in the eleventh invention, it is preferable that the diameter of the fiber in the small-diameter portion is 100 nanometers or more and 10 micrometers or less, and the diameter of the functional particle is 300 nanometers or more and 200 micrometers or less (twelfth invention).

[0020] Alternatively, a method for manufacturing a thermally expandable functional nonwoven fabric can be provided, comprising the following steps: a first step of heating the synthetic resin to melt it or dissolving it in a solvent to liquefy it, thereby dispersing the thermally expandable functional particles into the liquefied synthetic resin; and a second step of following the first step of spinning the liquefied synthetic resin containing the functional particles using a melt-blowing method or an electrospinning method to form long fibers and then forming a nonwoven fabric (the thirteenth invention). Invention Effects

[0021] According to the functional nonwoven fabric of the present invention (first invention), a functional nonwoven fabric capable of suppressing the shedding of functional particles and suppressing the reduction of air permeability of the nonwoven fabric can be provided. Furthermore, according to the functional nonwoven fabric of the first invention, even with an increase in the amount of functional particles incorporated, the reduction of air permeability of the nonwoven fabric can be suppressed. Additionally, according to the functional nonwoven fabric of the first invention, even with an increase in the amount of functional particles incorporated, the functional particles can be uniformly dispersed within the nonwoven fabric.

[0022] Furthermore, if it becomes a functional nonwoven fabric of the second invention, the effects obtained through the first invention can be made more effective. Furthermore, if it becomes a functional nonwoven fabric of the third invention, it can more effectively prevent the shedding of functional particles. Furthermore, if it becomes a functional nonwoven fabric of the fourth invention, it can more effectively suppress the decrease in the air permeability of the nonwoven fabric even if the amount of functional particles is increased. Furthermore, if the functional nonwoven fabric becomes the fifth or sixth invention, heating can change the functional nonwoven fabric in a way that reduces its air permeability. In particular, when the functional nonwoven fabric of the fifth or sixth invention is heated using airflow, the functional particles can expand rapidly, causing a rapid change in air permeability.

[0023] Furthermore, the method for manufacturing the functional nonwoven fabric according to the seventh invention can effectively manufacture the functional nonwoven fabric of any one of the first to sixth inventions.

[0024] The functional nonwoven fabric with thermal expansion properties according to the eighth invention (hereinafter also referred to as "functional nonwoven fabric with thermal expansion properties" as "thermally expandable nonwoven fabric") comprises long fibers having a large diameter portion and a small diameter portion to form the thermally expandable nonwoven fabric, and the nonwoven fabric is breathable. The thermally expandable nonwoven fabric of the present invention can be used in a configuration and structure in which airflow passes through the interior of the nonwoven fabric. Furthermore, the eighth invention's thermally expandable nonwoven fabric expands rapidly using high-temperature air. That is, because the thermally expandable nonwoven fabric is breathable, high-temperature air easily enters and passes through the fabric when it arrives. As a result, the nonwoven fabric as a whole becomes easily heated by high-temperature air. The thermally expandable functional particles contained in the large-diameter portion of the long fibers expand rapidly due to the rapid heating of the surrounding high-temperature air. Thus, the thermally expandable nonwoven fabric expands rapidly using high-temperature air. For example, if the thermally expandable nonwoven fabric of the eighth invention is configured in a manner that covers the ventilation holes of the ceiling, the thermally expandable nonwoven fabric configured in the holes will expand rapidly when hot air passes through the ventilation holes, restricting the air permeability of the thermally expandable nonwoven fabric and blocking the ventilation holes of the board.

[0025] Furthermore, if it becomes the ninth invention, the thermally expandable nonwoven fabric can reliably expand even in the presence of high-temperature air, such as during a fire. Moreover, if it becomes the tenth invention, the layer of synthetic resin covering the functional particles becomes very thin, and the thermally expandable functional particles are rapidly heated using high-temperature air, causing the nonwoven fabric to expand even more quickly. Furthermore, if it becomes the eleventh or twelfth invention of a thermally expandable nonwoven fabric, it will have better air permeability, and the thermally expandable nonwoven fabric can expand more rapidly by using high-temperature air.

[0026] Furthermore, according to the method for manufacturing a functional nonwoven fabric with thermal expansion properties according to the thirteenth invention, it is possible to effectively manufacture the thermal expansion nonwoven fabric of any one of the eighth to twelfth inventions. Attached Figure Description

[0027] Figure 1 This is a schematic diagram showing the structure of the functional nonwoven fabric according to the first embodiment. Figure 2 This is a schematic diagram showing the structure of the large-diameter section and the small-diameter section. Figure 3 These are microscope photographs illustrating the structure of an embodiment of the functional nonwoven fabric according to the first embodiment. Figure 4 This is a microscope photograph showing the structure of Example 2 of the functional nonwoven fabric. Figure 5 This is a microscope photograph showing the structure of Example 3 of the functional nonwoven fabric. Figure 6 This is a schematic diagram showing the structure of the thermally expandable nonwoven fabric 5 according to the second embodiment. Figure 7 This is a cross-sectional schematic diagram illustrating an example of the use of the thermally expandable nonwoven fabric 5 according to the second embodiment. Detailed Implementation

[0028] The following description uses an example with reference to illustrate the use of thermally expanding particles as functional particles. The invention is not limited to the individual embodiments shown below, and may be implemented in different ways.

[0029] The functional nonwoven fabric 1 of the first embodiment is a functional nonwoven fabric comprising long fibers made of synthetic resin in which functional particles with a specified function are integrally formed 4, 4. Here, the so-called long fiber is a fiber that is longer than the short fibers in the fibers constituting the nonwoven fabric. Long fibers are also called filaments. Short fibers are called staple fibers, etc., and their length is approximately a few mm to tens of cm relative to the short fibers. Long fibers are fibers that have not been cut short. Typically, long fibers are nonwoven by directly stacking them through meltblowing, electrospinning, or spunbonding. In addition, the functional nonwoven fabric 1 does not have to be composed of only long fibers; it may also contain short fibers, and may also be blended in a way that long fibers and short fibers are intertwined.

[0030] Although not mandatory, it is preferred that the amount of functional particles 4, 4 relative to functional nonwoven fabric 1 is about 10 to 500 g / m².

[0031] Furthermore, functional nonwoven fabrics can be single-layered, or they can be laminated nonwoven fabrics obtained by stacking multiple nonwoven layers, films, sheets, woven fabrics, etc. Additionally, functional nonwoven fabrics can also be composite nonwoven fabrics obtained by stacking layers of long-fiber nonwoven materials on woven or web-like raw materials. Long fibers made of synthetic resin with integrated functional particles can be contained within any single nonwoven layer.

[0032] In addition, all the long fibers contained in the functional nonwoven fabric 1 can be long fibers made of synthetic resin with integrated functional particles, but the functional nonwoven fabric 1 can also contain other long fibers, such as long fibers without integrated functional particles. Although not strictly necessary, the functional nonwoven fabric 1 of this embodiment is a single-layer functional nonwoven fabric that has been nonwoven by spinning long fibers made of synthetic resin with integrated functional particles through electrospinning.

[0033] Figure 1 The functional nonwoven fabric 1 of the first embodiment is schematically shown in the diagram. Additionally, Figure 3 These are microscope images of an embodiment of the functional nonwoven fabric according to the first embodiment. Additionally, in Figure 1 In the middle, the small diameter part 3, 3 is represented by a solid line. The functional nonwoven fabric 1 contains long fibers whose diameter varies along the long side of the fiber in an alternating arrangement of multiple large-diameter portions 2, 2 and small-diameter portions 3, 3. It can be said that the long fibers are composed of a series of large-diameter portions 2, 2 and small-diameter portions 3, 3.

[0034] The small-diameter portions 3, 3 of the long fibers are monofilaments formed from the synthetic resin. The synthetic resin is not particularly limited to any resin capable of fiberization, but a synthetic resin suitable for manufacturing long fibers using melt-blowing or electrospinning methods is preferred. Furthermore, a synthetic resin that can bond with functional particles described later is preferred. Preferably, polyurethane resin, vinyl chloride resin, etc., can be used as the synthetic resin for forming the long fibers.

[0035] The monofilaments forming the small diameter portions 3, 3 may be composed solely of the aforementioned synthetic resin, but may also contain other compounding materials, such as reinforcing materials, additive materials, particles with diameters smaller than the small diameter portion, and agents that improve the properties of the synthetic resin. Furthermore, the monofilaments forming the small diameter portions 3, 3 may also substantially not contain the functional particles described later.

[0036] While not strictly necessary, the fiber diameter of the minor diameter portions 3, 3 is preferably 100 nanometers or more and 10 micrometers or less. Particularly preferred is a fiber diameter of 500 nanometers or more and 3 micrometers or less. Here, the fiber diameter refers to the diameter of the fiber measured in a direction orthogonal to the fiber's extension direction. For example, the fiber diameter is determined by taking a microscopic photograph of the functional nonwoven fabric 1 and measuring the fiber diameter of the minor diameter portion on the photograph. Preferably, the fiber diameter is measured at 10 or 20 minor diameter portions, and the average value obtained by averaging these measurements is taken as the fiber diameter of the minor diameter portion.

[0037] At least a portion of the large-diameter portions 2, 2 is formed by solidifying multiple functional particles 4, 4 into rope-like or clump-like shapes using the synthetic resin. Here, "rope-like" means that, for the shape of the large-diameter portion, the length of the fiber in the extension direction is greater than the length of the fiber in the direction orthogonal to the extension direction, preferably more than three times. "Clump-like" means that, for the shape of the large-diameter portion, the length of the fiber in the extension direction is equal to the length of the fiber in the direction orthogonal to the extension direction, preferably more than half and less than two times. Furthermore, large-diameter portions that do not contain functional particles or contain only one functional particle may also exist within the long fibers.

[0038] The diameter of the large-diameter portions 2, 2 is larger than the fiber diameter of the small-diameter portions 3, 3. The diameter of the large-diameter portion is the diameter measured in a direction orthogonal to the fiber's extension direction. Preferably, the diameter is measured at 10 or 20 locations along the large-diameter portion, and the average of these measurements is taken as the diameter of the large-diameter portion. While not strictly necessary, it is preferable that the diameter of the large-diameter portions 2, 2 is 150 nanometers or more and 300 micrometers or less. Particularly preferred is that the diameter of the large-diameter portions 2, 2 is 1 micrometer or more and 50 micrometers or less. Furthermore, it is preferable that the diameter of the large-diameter portions 2, 2 is 3 to 20 times the fiber diameter of the small-diameter portions 3, 3, and particularly preferred is 4 to 10 times.

[0039] Figure 2 The structure of the large-diameter portions 2, 2 and the small-diameter portions 3, 3 is schematically shown. Although not essential, it is present in... Figure 2In the embodiment shown, the large-diameter portion 2 contains a plurality of functional particles 4, 4. Preferably, these functional particles 4, 4 are surrounded or bonded by the same synthetic resin as that constituting the small-diameter portion, and solidified into a rope or clump shape. In the large-diameter portions 2, 2, the functional particles 4, 4 can be bonded together by synthetic resin, or one or more functional particles 4, 4 can be surrounded by a synthetic resin that forms a film or mesh. In the large-diameter portions 2, 2, only one functional particle may exist in the radial direction of the fiber, but multiple functional particles may also exist in the radial direction of the fiber. At the ends of the large-diameter portions 2, 2, the large-diameter portion 2 is continuous with the small-diameter portion 3, so that the synthetic resin contained in the large-diameter portion directly becomes the monofilament of the small-diameter portion 3, 3.

[0040] The functional particles contained in the large-diameter portions 2 and 2 have a specified function. Although not strictly necessary, in the functional nonwoven fabric 1 of this embodiment, thermally expandable particles are used as functional particles. Examples of thermally expandable particles include thermally expandable microcapsules, thermally expandable graphite, and aluminum phosphite. Examples of thermally expandable aluminum phosphite particles include, for example, "APA-100" from Taihei Chemical Industry Co., Ltd. Among aluminum phosphite particles, aluminum hydrogen phosphite ("NSF" from Taihei Chemical Industry Co., Ltd.) is particularly preferred. These particles have the property of expanding when heated to a specified temperature. If the large-diameter portions 2 and 2 contain thermally expandable particles, when the functional nonwoven fabric is heated, the large-diameter portions 2 and 2 expand, changing in a way that the voids in the nonwoven fabric become smaller and narrower, resulting in a decrease in the air permeability of the nonwoven fabric.

[0041] The fiber diameter Ds of the small-diameter portions 3, 3 is less than or equal to the diameter Dp of the functional particles 4, 4 contained in the large-diameter portions 2, 2. The fiber diameter Ds of the small-diameter portions 3, 3 and the diameter Dp of the functional particles 4, 4 can be substantially the same. Furthermore, the diameter Dp of the functional particles 4, 4 as described in this invention is the volume average particle size. The diameter Dp of the functional particles 4, 4 contained in the large-diameter portions is typically 300 nanometers or more and 200 micrometers or less. Additionally, although not mandatory, it is preferable that the fiber diameter Ds of the small-diameter portions 3, 3 is 1 / 100 or more of the diameter Dp of the functional particles 4, 4.

[0042] The manufacturing method of the functional nonwoven fabric 1 according to the first embodiment described above will be explained. The functional nonwoven fabric 1 can be manufactured using meltblown or electrospinning methods.

[0043] First, as the first step, liquefied synthetic resin is mixed with functional particles. The synthetic resin is liquefied by heating and melting or by dissolving in a solvent. The functional particles are then mixed and dispersed into the liquefied synthetic resin. Alternatively, the functional particles can be pre-kneaded into the synthetic resin, and the synthetic resin with the kneaded functional particles can be heated to melt it, resulting in a liquefied synthetic resin with dispersed functional particles. Alternatively, the functional particles can be mixed and dispersed after the synthetic resin has been dissolved and liquefied using a solvent or similar method.

[0044] In this embodiment, the polyurethane resin is dissolved in a solvent to liquefy it, and aluminum phosphite powder (manufactured by Taihei Chemical Industry Co., Ltd., NSF, with a volume average particle size of 5 micrometers) is mixed with the liquefied polyurethane resin as functional particles 4,4 and stirred to disperse the functional particles 4,4.

[0045] Next, as the second step, following the first step, the liquid synthetic resin in which the functional particles 4, 4 are dispersed is spun into long fibers using melt-blowing or electrospinning, and then stacked to form a nonwoven fabric.

[0046] Liquid synthetic resin ejected from the spinning nozzle is stretched into fine fibers by centrifugal force, gravity, electrostatic force, etc. These fine fibers become the small-diameter portions 3, 3 of the aforementioned long fibers. At this time, if functional particles 4, 4 are also ejected from the nozzle along with the liquid synthetic resin, the aggregated portion of the functional particles 4, 4 solidifies into rope-like or clump-like structures to form the large-diameter portions 2, 2, and the remaining synthetic resin is stretched to form the small-diameter portions 3, 3. This continuously forms a series of long fibers with alternating large-diameter portions 2, 2 and small-diameter portions 3, 3. The formed long fibers are solidified by solvent evaporation and temperature reduction, and are deposited on the base of the spinning device (nonwoven fabric manufacturing device), thereby producing a functional nonwoven fabric 1.

[0047] In the embodiment, “NSF” (average particle size 5 micrometers) as aluminum hydrogen phosphate was used as the functional particle to obtain a functional nonwoven fabric 1 with a diameter of about 2 to 10 micrometers (average diameter 6 micrometers) for the large diameter portion 2, 2 and a diameter of about 0.5 to 1.5 micrometers (average diameter 0.9 micrometers) for the small diameter portion 3, 3. Figure 3 The image shows a microscope photograph of it.

[0048] By adjusting the amount of functional particles, the viscosity of the liquid synthetic resin, the delivery speed, the nozzle diameter, the applied voltage of the electrostatics, the distance from the nozzle to the base, the ambient temperature, etc., the size, length, diameter, and ratio of the large diameter section 2, 2 and the small diameter section 3, 3 can be adjusted.

[0049] If the aforementioned functional nonwoven fabric 1 is manufactured using meltblown or electrospinning methods, the synthetic resin is drawn out from the portion forming the large diameter section to the portion forming the small diameter section during spinning, thus reducing the amount of synthetic resin remaining in the large diameter section. Consequently, the synthetic resin coating covering the functional particles in the large diameter section becomes thinner or forms a mesh. When the functional particles undergo mass exchange, adsorption, or reaction on the particle surface, the thinning or meshing of the synthetic resin coating allows for more effective utilization of the functional particles' functions, which is preferable.

[0050] The function and effect of the functional nonwoven fabric 1 in the above embodiments will be explained. In conventional functional nonwoven fabrics, such as those described in Patent Document 1, functional particles are subsequently attached to the nonwoven fibers to manufacture the fabric. In the prior art, adhesives are used to reliably attach the functional particles. However, while adhesives can suppress the shedding of functional particles, they can also clog the pores of the nonwoven fabric, reducing air permeability. Especially if the amount of functional particles is increased, the adhesive and functional particles adhere to the fibers in a plate-like or film-like manner, causing blockage and significantly reducing air permeability. Furthermore, in the prior art, functional particles are attached to the nonwoven fabric in a filtered manner. Therefore, if the amount of functional particles is increased, the functional particles tend to concentrate on the surface of the nonwoven fabric, also reducing air permeability.

[0051] In the functional nonwoven fabric 1 of the above embodiment, at least a portion of the large-diameter portions 2, 2 contains the functional particles 4, 4, forming long fibers with alternating large-diameter portions 2, 2 and small-diameter portions 3, 3, and the functional nonwoven fabric 1 contains such long fibers. Therefore, the functional particles 4, 4 are firmly integrated with the long fibers, and the loss of functional particles 4, 4 from the functional nonwoven fabric 1 can be suppressed. Especially when the functional particles 4, 4 are solidified into ropes or clumps using synthetic resin to form the large diameter portion 2, 2, it is possible to more reliably suppress the functional particles 4, 4 from falling off the functional nonwoven fabric 1.

[0052] Furthermore, the long fibers contained in the functional nonwoven fabric 1 have a diameter variation along the long side direction of the fiber, arranged in an alternating pattern of multiple large-diameter portions 2, 2 and small-diameter portions 3, 3. Therefore, when the fibers overlap, portions of large-diameter portions 2, 2 contact each other, and portions of large-diameter portions 2 and small-diameter portions 3 contact each other. If such portions are formed, gaps are generated in the thickness direction when the long fibers are stacked and nonwoven. Therefore, in the aforementioned functional nonwoven fabric 1, even if the fiber diameter of the small-diameter portion 3 is made thinner, it is possible to prevent the overlapping of long fibers from being flattened into a planar shape, the nonwoven fabric from becoming a thin plate, and the air permeability from decreasing. That is, the long fibers contained in the functional nonwoven fabric 1 have a diameter variation along the long side direction of the fiber, arranged in an alternating pattern of multiple large-diameter portions and small-diameter portions. Therefore, the overlapping of long fibers forms a three-dimensional structure with a three-dimensional thickness, which can suppress the decrease in air permeability. Furthermore, in the functional nonwoven fabric 1, since the fiber diameter of the small diameter portion 3, 3 is less than the diameter of the functional particles 4, 4 contained in the large diameter portion, it is possible to suppress the fibers in the small diameter portion from reducing the gap between the fibers of the nonwoven fabric, thereby suppressing the reduction of air permeability.

[0053] Furthermore, as with the functional nonwoven fabric 1 described above, when the functional particles 4, 4 are solidified into ropes or clumps using synthetic resin to form large-diameter portions 2, 2 and integrated with long fibers, the decrease in air permeability of the nonwoven fabric can be suppressed even when the amount of functional particles is increased. If the amount of functional particles is increased, the proportion of the large-diameter portions 2, 2 in the space of the functional nonwoven fabric 1 increases. However, since the large-diameter portions 2, 2 are ropes or clumps, even if the large-diameter portions come into contact with each other, space remains around them, preventing the functional particles and adhesives from forming plates or films that clog the gaps between fibers, as is the case in the prior art. Therefore, in the functional nonwoven fabric 1, the decrease in air permeability of the nonwoven fabric can be suppressed even when the amount of functional particles is increased. This effect is further amplified by increasing the ratio of the fiber diameter of the large-diameter portions to the fiber diameter of the small-diameter portions.

[0054] Furthermore, in the functional nonwoven fabric 1 of the above embodiment, the large-diameter portions 2, 2 of the long fibers contain functional particles 4, 4. Therefore, by simply stacking the long fibers, the functional particles 4, 4 can be dispersed approximately uniformly. That is, the functional particles 4, 4 can be uniformly dispersed throughout the entire thickness direction of the nonwoven fabric. Therefore, the problem of functional particles concentrating on the surface of the nonwoven fabric due to increasing the amount of functional particles, as is the case in the prior art, is avoided.

[0055] Furthermore, although not strictly necessary, as with the functional nonwoven fabric 1 of the above embodiment, when the fiber diameter of the small diameter portions 3, 3 is more than 1 / 100 of the diameter of the functional particles, the height-increasing effect brought by the large diameter portions 2, 2 can be obtained, and the small diameter portions 3, 3 can be used to firmly connect the large diameter portions 2, 2, thus more effectively suppressing the shedding of the large diameter portions 2, 2 and the functional particles 4, 4.

[0056] Furthermore, although not strictly necessary, as with the functional nonwoven fabric 1 of the above embodiment, the above-mentioned effects can be more effectively achieved when the fiber diameter of the small diameter portion 3, 3 is 100 nanometers or more and 10 micrometers or less, and the diameter of the functional particles 4, 4 is 300 nanometers or more and 200 micrometers or less. Even when the amount of functional particles is increased, the reduction in the air permeability of the nonwoven fabric can be suppressed particularly effectively.

[0057] Furthermore, although not strictly necessary, as with the functional nonwoven fabric 1 described in the above embodiment, when the functional particles 4, 4 are thermally expandable particles, heating during use can change the air permeability of the nonwoven fabric, thereby reducing its air permeability. In particular, since the functional nonwoven fabric 1 is breathable and the thermally expandable functional particles are dispersed throughout the fabric, heating it with airflow can cause the functional particles to expand rapidly, resulting in a rapid change in air permeability. Such a functional nonwoven fabric can be used, for example, in the ventilation channels of an air supply system, and can be used for applications such as: utilizing the air permeability of the functional nonwoven fabric 1 for ventilation under normal conditions (when the air temperature is low), and reducing the air permeability of the functional nonwoven fabric 1 when hot air flows through the ventilation path due to a fire, thus suppressing the flow of hot air.

[0058] Furthermore, although not strictly necessary, as with the functional nonwoven fabric 1 of the above embodiment, and in the case where the functional particles 4, 4 are aluminum phosphite particles, heating during use can effectively change the functional nonwoven fabric in a way that reduces air permeability.

[0059] Furthermore, according to the manufacturing method of the functional nonwoven fabric 1 using the meltblown method or electrospinning method described above, the functional nonwoven fabric 1 having large-diameter and small-diameter portions can be manufactured stably and effectively. Moreover, when the functional nonwoven fabric 1 is manufactured using the meltblown method or electrospinning method, during spinning, the small-diameter portions 3 and 3 are formed by drawing out synthetic resin from the portions that should be large-diameter portions 2 and 2. Therefore, less synthetic resin remains in the large-diameter portions 2 and 2, and the synthetic resin film covering the functional particles 4 and 4 in the large-diameter portions 2 and 2 becomes thinner or forms a mesh. This makes it easier to utilize the functions of the functional particles 4 and 4. For example, if the functional particles 4 and 4 are thermally expandable particles, if the synthetic resin film covering the functional particles 4 and 4 becomes thinner, the functional particles expand more rapidly upon contact with a high-temperature airflow.

[0060] Furthermore, according to the above-described method for manufacturing functional nonwoven fabric 1 using electrospinning, high temperatures can be avoided during spinning, which is advantageous for integrating functional particles with poor heat resistance into the functional nonwoven fabric. Examples of functional particles with poor heat resistance include aromatic functional particles containing fragrances.

[0061] The invention is not limited to the embodiments described above and can be implemented with various modifications. Other embodiments of the invention will be described below, focusing on the parts that differ from the embodiments described above, while detailed descriptions of the same parts are omitted. Furthermore, some of these embodiments can be combined with each other or substituted with other parts. For example, in the description of the above embodiments, only the long fibers in the interwoven portions of the functional nonwoven fabric 1 are in contact with each other. However, the long fibers can also be bonded together in the interwoven portions. For example, in the interwoven portions of long fibers, the large diameter portions 2, 2 can be bonded to each other, or three or more (preferably four or more) small diameter portions 3, 3 can be connected to a large diameter portion in appearance. If such a structure is formed, the small diameter portions 3, 3 connect the large diameter portions 2, 2 into a mesh, which easily maintains the three-dimensional structure of the functional nonwoven fabric 1 and provides good air permeability.

[0062] Other embodiments of the functional nonwoven fabric 1 manufactured by changing manufacturing conditions, etc., are shown below. Figure 4 These are microscope images showing the structure of the functional nonwoven fabric of Example 2, manufactured by changing manufacturing conditions, etc. Compared with the above-described example, the manufacturing conditions were adjusted to make the long fibers thicker overall. The synthetic resin is thermoplastic polyurethane resin (TPU), the functional particles are aluminum hydrogen phosphite (average particle size 5 micrometers), and the manufacturing process is the same as in the above-described example.

[0063] In the functional nonwoven fabric of Example 2, the diameter of the large-diameter portions 2, 2 is approximately 2 to 15 micrometers (average diameter 8 micrometers) and the diameter of the small-diameter portions 3, 3 is approximately 0.5 to 1.8 micrometers (average diameter 1.0 micrometer). Furthermore, in the nonwoven fabric of Example 2, it can also be seen that three or more small-diameter portions extend from the large-diameter portions in a branching manner.

[0064] Figure 5 These are microscope images showing the structure of the functional nonwoven fabric of Example 3, manufactured with altered manufacturing conditions. Compared to the above-described examples, the manufacturing conditions were adjusted by reducing the amount of functional particles incorporated. The synthetic resin is thermoplastic polyurethane resin (TPU), the functional particles are "NSF" (average particle size 5 micrometers), and the manufacturing process is the same as in the above-described examples.

[0065] In the functional nonwoven fabric of Example 3, the diameter of the large-diameter portions 2, 2 is approximately 3 to 8 micrometers (average diameter 5 micrometers), and the diameter of the small-diameter portions 3, 3 is approximately 0.3 to 1.0 micrometers (average diameter 0.6 micrometers). Furthermore, in the nonwoven fabric of Example 3, more than three small-diameter portions can be seen extending from the large-diameter portions in a branching manner.

[0066] The functional nonwoven fabrics in Examples 1, 2, and 3 all have appropriate air permeability, and the functional particles expand and the air permeability decreases when exposed to hot air.

[0067] In the description of the above embodiments, the case where the functional particles are particles with thermal expansion properties has been described; however, the functions of the functional particles are not limited to thermal expansion properties. For example, the functional particles may also be particles with water retention or water absorption properties. In this case, it is also possible to improve the water absorption of the nonwoven fabric, or to generate a cooling effect by vaporizing the absorbed moisture.

[0068] In addition, functional particles can also include particles such as aldehyde adsorbents and activated carbon particles, which have deodorizing and odor-removing functions. Functional nonwoven fabrics containing such functional particles can be used for deodorizing and odor-removing purposes. Furthermore, if fragrance-containing particles are used as functional particles, the functional nonwoven fabric can have a fragrance function.

[0069] In addition, functional particles can also be particles with heat-generating or heat-absorbing properties. Furthermore, functional particles can also be particles with heat-conducting or electrical properties. Additionally, functional particles can also be particles that react with chemical substances present in the environment where the functional nonwoven fabric is used, or particles that act as catalysts to promote reactions. In addition, functional particles can also be particles with optical functions such as light absorption, low reflection, fluorescence, reflectivity, and refraction.

[0070] Furthermore, the aforementioned functional nonwoven fabrics can also be applied to other technical fields besides those exemplified in the above embodiments. For example, functional nonwoven fabrics integrating deodorizing functional particles can be used for room deodorization purposes.

[0071] The following describes an embodiment (second embodiment) of the functional nonwoven fabric, especially the case where the functional nonwoven fabric is a thermally expandable nonwoven fabric. The following description, with reference to figures, illustrates an embodiment of the invention comprising a thermally expandable functional nonwoven fabric (hereinafter referred to simply as "thermally expandable nonwoven fabric") that integrates thermally expandable functional particles with long fibers. The invention is not limited to the individual embodiments shown below, and may be implemented in other ways.

[0072] The second embodiment of the thermally expandable nonwoven fabric 5 is a thermally expandable nonwoven fabric containing long fibers made of synthetic resin with thermally expandable functional particles 4, 4 integrated therein. Here, the so-called long fibers are fibers that are longer than the short fibers in the fibers constituting the nonwoven fabric. Long fibers are also called filaments. Short fibers are called short filaments, etc., and their length is approximately a few mm to tens of cm. Long fibers are fibers that have not been cut short. Long fibers are typically spun using meltblown, electrospinning, or spunbond methods and directly stacked to form a nonwoven fabric. In addition, the thermally expandable nonwoven fabric 5 does not have to be composed of only long fibers; it may also contain short fibers, or it may be a blend of long and short fibers intertwined.

[0073] Although not mandatory, it is preferred that the amount of functional particles 4, 4 relative to the thermally expandable nonwoven fabric 5 is about 10 to 500 g / m².

[0074] Furthermore, thermally expandable nonwoven fabrics can be single-layered, or they can be multilayered nonwoven fabrics obtained by laminating multiple nonwoven layers, films, sheets, woven fabrics, etc. Additionally, thermally expandable nonwoven fabrics can also be composite nonwoven fabrics in which layers of long-fiber nonwoven materials are laminated onto woven or web-like raw materials. Long fibers made of synthetic resin with integrated functional particles can be contained within any single nonwoven layer.

[0075] In addition, all the long fibers contained in the thermally expandable nonwoven fabric 5 can be long fibers made of synthetic resin with integrated functional particles, but the thermally expandable nonwoven fabric 5 can also contain other long fibers, such as long fibers without integrated functional particles. Although not strictly necessary, the thermally expandable nonwoven fabric 5 in this embodiment is a single-layer thermally expandable nonwoven fabric obtained by electrospinning a long-fiber nonwoven fabric made of synthetic resin with integrated functional particles.

[0076] Figure 6 The thermally expandable nonwoven fabric 5 of the second embodiment is schematically shown. Additionally, Figure 3 These are microscope images of an embodiment of the thermally expandable nonwoven fabric described in this embodiment. Additionally, in... Figure 6 The small diameter part 3, 3 is represented by a solid line. The thermally expandable nonwoven fabric 5 contains long fibers whose diameter varies along the long side of the fiber in an alternating arrangement of multiple large-diameter portions 2, 2 and small-diameter portions 3, 3. It can be said that the long fibers are composed of fibers that form a chain of large-diameter portions 2, 2 and small-diameter portions 3, 3.

[0077] The small-diameter portions 3, 3 of the long fibers are monofilaments formed from the synthetic resin. There are no particular limitations on the synthetic resin as long as it can be fibrous, but a synthetic resin suitable for manufacturing long fibers using melt-blowing or electrospinning methods is preferred. Furthermore, a synthetic resin that can bond with functional particles described later is preferred. Preferably, polyurethane resin, vinyl chloride resin, etc., can be used as the synthetic resin as the raw material for the long fibers.

[0078] The monofilaments forming the small diameter portions 3, 3 may be composed solely of the aforementioned synthetic resin, but may also contain other compounding materials, such as reinforcing materials, additive materials, particles with a diameter smaller than the small diameter portion, and agents that improve the properties of the synthetic resin. Furthermore, the monofilaments forming the small diameter portions 3, 3 may also substantially not contain functional particles with thermal expansion properties.

[0079] While not strictly necessary, the fiber diameter of the small-diameter portions 3, 3 is preferably 100 nanometers or more and 10 micrometers or less. Particularly preferred is a fiber diameter of 500 nanometers or more and 3 micrometers or less. Here, the fiber diameter refers to the diameter of the fiber measured in a direction orthogonal to the fiber's extension direction. The fiber diameter is determined by taking a microscopic photograph of the thermally expandable nonwoven fabric 5 and measuring the fiber diameter of the small-diameter portion on the photograph. Preferably, the fiber diameter is measured at 10 or 20 small-diameter portions, and the average of these measurements is taken as the fiber diameter of the small-diameter portion.

[0080] Large-diameter portions 2, 2 contain thermally expandable functional particles 4, 4. While not strictly necessary, at least a portion of the large-diameter portions 2, 2 is formed by coagulating multiple functional particles 4, 4 into a rope-like or clump-like shape using the synthetic resin. Here, "rope-like" means that, for the shape of the large-diameter portion, the length of the fiber in the extension direction is greater than the length of the fiber in the direction perpendicular to the extension direction, preferably more than three times. "Clump-like" means that, for the shape of the large-diameter portion, the length of the fiber in the extension direction is equal to the length of the fiber in the direction perpendicular to the extension direction, preferably more than half and less than two times. Furthermore, long fibers may also exist in large-diameter portions that do not contain functional particles or contain only one functional particle.

[0081] The diameter of the large-diameter portions 2, 2 is larger than the fiber diameter of the small-diameter portions 3, 3. The diameter of the large-diameter portion is the diameter measured in a direction orthogonal to the fiber's extension direction. Preferably, the diameter is measured at 10 or 20 locations along the large-diameter portion, and the average of these measurements is taken as the diameter of the large-diameter portion. While not strictly necessary, it is preferable that the diameter of the large-diameter portions 2, 2 is 150 nanometers or more and 300 micrometers or less. Particularly preferred is that the diameter of the large-diameter portions 2, 2 is 1 micrometer or more and 50 micrometers or less. Furthermore, it is preferable that the diameter of the large-diameter portions 2, 2 is 3 to 20 times the fiber diameter of the small-diameter portions 3, 3, and particularly preferred is 4 to 10 times.

[0082] Figure 2 The structure of the large-diameter portions 2, 2 and the small-diameter portions 3, 3 is schematically shown in the diagram. Figure 2 In the example of the embodiment shown, the large-diameter portion 2 contains a plurality of thermally expandable functional particles 4, 4. The large-diameter portion 2 may contain only one thermally expandable functional particle. Alternatively, a portion of the large-diameter portion may contain thermally expandable functional particles, resulting in a large-diameter portion without functional particles. Although not mandatory, in the illustrated arrangement, these functional particles 4, 4 are surrounded or bonded by the same synthetic resin as that constituting the small-diameter portion, solidifying into a rope or clump shape. In the large-diameter portions 2, 2, the functional particles 4, 4 may be bonded together by synthetic resin, or one or more functional particles 4, 4 may be surrounded by synthetic resin that forms a film, mesh, or fiber bundle. In the large-diameter portions 2, 2, only one functional particle may exist in the radial direction of the fiber, but multiple functional particles may also exist in the radial direction of the fiber. At the ends of the large-diameter portions 2, 2, the large-diameter portion 2 is continuous with the small-diameter portion 3, so that the synthetic resin contained in the large-diameter portion directly becomes the monofilament of the small-diameter portion 3, 3.

[0083] The functional particles contained in the large-diameter portions 2 and 2 are thermally expandable. That is, in the thermally expandable nonwoven fabric 5 of this embodiment, thermally expandable particles are used as functional particles. Examples of thermally expandable particles include thermally expandable microcapsules, thermally expandable graphite, and aluminum phosphite. Examples of thermally expandable aluminum phosphite particles include "APA-100" from Taihei Chemical Industry Co., Ltd. Among aluminum phosphite particles, aluminum hydrogen phosphite particles ("NSF" from Taihei Chemical Industry Co., Ltd.) are particularly preferred. These particles have the property of expanding when heated to a specified temperature. If the large-diameter portions 2 and 2 contain thermally expandable particles, when the thermally expandable nonwoven fabric is heated, the large-diameter portions 2 and 2 expand, changing in a way that reduces and narrows the gaps in the nonwoven fabric, resulting in a decrease in the air permeability of the nonwoven fabric.

[0084] The fiber diameter Ds of the small-diameter portions 3, 3 is less than or equal to the diameter Dp of the functional particles 4, 4 contained in the large-diameter portions 2, 2. The fiber diameter Ds of the small-diameter portions 3, 3 and the diameter Dp of the functional particles 4, 4 can be substantially the same. Furthermore, the diameter Dp of the functional particles 4, 4 in this invention is the volume average particle size. The diameter Dp of the functional particles 4, 4 contained in the large-diameter portions is typically 300 nanometers or more and 200 micrometers or less. Additionally, although not mandatory, it is preferable that the fiber diameter Ds of the small-diameter portions 3, 3 is 1 / 100 or more of the diameter Dp of the functional particles 4, 4.

[0085] An example of a method for manufacturing the thermally expandable nonwoven fabric 5 according to the second embodiment described above will be explained. The thermally expandable nonwoven fabric 5 can be manufactured using meltblown or electrospinning methods.

[0086] First, as the first step, liquefied synthetic resin is mixed with thermally expandable functional particles. The synthetic resin is liquefied by heating and melting or by dissolving in a solvent. The functional particles are then mixed and dispersed into the liquefied synthetic resin. Alternatively, the functional particles can be pre-kneaded into the synthetic resin, and the synthetic resin with the kneaded functional particles can be heated to melt it, resulting in a liquefied synthetic resin with dispersed functional particles. Alternatively, the functional particles can be mixed and dispersed after the synthetic resin has been dissolved in a solvent or similar medium to become liquefied.

[0087] In this embodiment, the polyurethane resin is dissolved in a solvent to liquefy the polyurethane resin, and aluminum hydrogen phosphite powder (manufactured by Taihei Chemical Industry Co., Ltd., NSF, with a volume average particle size of 5 micrometers) is mixed into the liquefied polyurethane resin as functional particles 4, 4 and stirred to disperse the aluminum hydrogen phosphite powder.

[0088] Next, as the second step, following the first step, the liquid synthetic resin in which the functional particles 4, 4 are dispersed is spun into long fibers using melt-blowing or electrospinning, and then stacked to form a nonwoven fabric.

[0089] Liquid synthetic resin delivered from the spinning nozzle is stretched into fine fibers by centrifugal force, gravity, electrostatic force, etc. These fine fibers become the small-diameter portions 3, 3 of the aforementioned long fibers. At this time, if functional particles 4, 4 are delivered from the nozzle together with the liquid synthetic resin, the concentrated portion of the functional particles 4, 4 solidifies into rope-like or clump-like shapes to form the large-diameter portions 2, 2, and the remaining synthetic resin is stretched to form the small-diameter portions 3, 3. The large-diameter portions 2, 2 and the small-diameter portions 3, 3 are continuously formed into a series of long fibers that alternately connect. The formed long fibers are solidified by solvent evaporation or temperature reduction and accumulate on the base of the spinning device to produce a thermally expandable nonwoven fabric 5.

[0090] In this embodiment, NSF (average particle size 5 μm) as aluminum hydrogen phosphate was used as the functional particle, resulting in a thermally expandable nonwoven fabric 5 with a large diameter portion 2, 2 having a diameter of approximately 2–10 μm (average diameter 6 μm) and a small diameter portion 3, 3 having a diameter of approximately 0.5–1.5 μm (average diameter 0.9 μm). The amount of functional particles 4, 4 relative to the obtained thermally expandable nonwoven fabric 5 is approximately 100 g / m². If a large number of long fibers are laminated, the amount of functional particles 4, 4 per unit area of ​​the thermally expandable nonwoven fabric 5 can be further increased. Furthermore, Figure 3 A microscope image of the thermally expandable nonwoven fabric of an embodiment is shown. Figure 3 In order to better understand the morphology of the fibers, only a very small portion of the nonwoven fabric in the thickness direction was photographed. Figure 4 , Figure 5 The same applies.

[0091] By adjusting the amount of functional particles, the viscosity of the liquid synthetic resin, the delivery speed, the nozzle diameter, the applied voltage of the electrostatics, the distance from the nozzle to the base, the ambient temperature, etc., the size, length, diameter, and ratio of the large diameter section 2, 2 and the small diameter section 3, 3 can be adjusted.

[0092] If the aforementioned thermally expandable nonwoven fabric 5 is manufactured using meltblown or electrospinning methods, during spinning, the synthetic resin is drawn out from the portion forming the large diameter section to the portion forming the small diameter section, thus reducing the amount of synthetic resin remaining in the large diameter section. Consequently, the synthetic resin coating covering the functional particles in the large diameter section becomes thinner or forms a mesh. When the functional particles undergo mass exchange, adsorption, or reaction on the particle surface, thinning the synthetic resin coating or making it a mesh allows for more effective utilization of the thermal expansion properties and other functions of the functional particles, which is preferable.

[0093] Figure 7 The cross-sectional view schematically illustrates an example of the use of the thermally expandable nonwoven fabric 5 of the second embodiment. The thermally expandable nonwoven fabric 5 of the second embodiment is installed in the cylindrical air passage 9. The air passage 9 is open at the left and right ends, as shown by the blank arrows, and is configured such that air flowing in from the left end flows out from the right end through the air passage 9.

[0094] The thermally expandable nonwoven fabric 5 is configured to divide the internal space of the air-permeable channel 9 into a left end side and a right end side. Preferably, as in this embodiment, the thermally expandable nonwoven fabric 5 is arranged at an angle relative to the airflow direction, so that the area of ​​the thermally expandable nonwoven fabric 5 is larger than the cross-sectional area of ​​the channel. Air flowing in from the left end of the air-permeable channel 9 passes through the breathable thermally expandable nonwoven fabric 5 and flows out from the right end of the air-permeable channel 9. Although not mandatory, it is preferable to provide a support component such as a metal mesh on the downstream side of the thermally expandable nonwoven fabric 5.

[0095] In this usage, under normal conditions, the air permeability of the thermally expandable nonwoven fabric 5 is maintained, and the air permeability channel 9 functions as an air permeability channel through which airflow passes. On the other hand, if a fire or other high-temperature event occurs upstream of the airflow, and air at a temperature higher than the expansion initiation temperature of the thermally expandable particles flows into the air permeability channel 9, the thermally expandable functional particles contained in the thermally expandable nonwoven fabric 5 expand due to the high-temperature airflow, thus restricting the air permeability of the thermally expandable nonwoven fabric 5. As a result, airflow becomes difficult to pass through the air permeability channel 9, and the flow of high-temperature airflow downstream can be suppressed or prevented.

[0096] The function and effect of the thermally expandable nonwoven fabric 5 in the above embodiments are explained. In conventional thermal expansion components like those in Patent Document 2, the component material itself is not breathable; when breathability is required, ventilation holes must be formed through molding or other methods. On the other hand, the thermal expansion nonwoven fabric 5 according to the above embodiment is constructed by including long fibers having large and small diameter portions, and the nonwoven fabric is breathable. Therefore, as described above... Figure 7 In the manner of use, the thermally expandable nonwoven fabric of the present invention can be used in a configuration and structure that allows airflow to pass through the interior of the nonwoven fabric.

[0097] Furthermore, in conventional thermal expansion components like those in Patent Document 2, the thermal expansion material is incorporated into the resin by embedding it. In these conventional components, the expansion occurs from the surface of the component, making it difficult to achieve uniform expansion throughout the entire component. In conventional thermal expansion components, heat transfer from the surface to the interior takes a considerable amount of time, resulting in delayed expansion. In particular, if only the surface of the component expands, the expanded portion acts as a heat-insulating layer, potentially hindering the expansion of the internal parts of the component.

[0098] In the thermally expandable nonwoven fabric 5 of the above embodiment, long fibers are formed in a series of alternating large diameter portions 2, 2 and small diameter portions 3, 3, and thermally expandable functional particles 4, 4 are contained in the large diameter portions 2, 2 of the long fibers. The thermally expandable nonwoven fabric 5 contains such long fibers. Furthermore, the long fibers contained in the thermally expandable nonwoven fabric 5 have a diameter variation along the long side direction of the fiber, arranged in an alternating pattern of multiple large-diameter portions 2, 2 and small-diameter portions 3, 3. Therefore, when the fibers overlap each other, portions of the large-diameter portions 2, 2 contact each other, and portions of the large-diameter portions 2 and small-diameter portions 3 contact each other. If such portions are formed, gaps are generated in the thickness direction when the long fibers are stacked and nonwoven. Therefore, in the aforementioned thermally expandable nonwoven fabric 5, even if the fiber diameter of the small-diameter portion 3 is made thinner, it is possible to prevent the overlapping of long fibers from being flattened into a planar shape, the nonwoven fabric from becoming a thin plate, and the air permeability from decreasing. That is, the long fibers contained in the thermally expandable nonwoven fabric 5 have a diameter variation along the long side direction of the fiber, arranged in a beaded pattern of multiple alternating large-diameter portions and small-diameter portions, so that the overlapping of long fibers forms a three-dimensional structure with a thickness, which can suppress the decrease in air permeability. Furthermore, in the thermally expandable nonwoven fabric 5, since the fiber diameter of the small diameter portion 3, 3 is less than the diameter of the functional particles 4, 4 contained in the large diameter portion, it is possible to suppress the fibers in the small diameter portion from reducing the gap between the fibers of the nonwoven fabric, and to suppress the air permeability of the nonwoven fabric from decreasing.

[0099] Therefore, the thermally expandable nonwoven fabric 5 of the above embodiment expands more rapidly in high-temperature air. That is, because the thermally expandable nonwoven fabric is breathable, when high-temperature air arrives, the air easily enters the interior of the nonwoven fabric and easily passes through it. As a result, the nonwoven fabric as a whole is easily heated by the high-temperature air. The thermally expandable functional particles contained in the large-diameter portion of the long fibers are rapidly heated and expanded by the high-temperature air surrounding the fibers. Thus, the thermally expandable nonwoven fabric can expand more rapidly in high-temperature air.

[0100] In addition, although not necessary, especially when the thermally expandable nonwoven fabric 5 of the above embodiment is made of aluminum hydrogen phosphate particles, the expansion of the functional particles is not only fast, but the expanded functional particles also have good fire resistance. Even when exposed to flames, they can maintain the expanded state, so they can also be used to block flames during a fire.

[0101] Furthermore, although not strictly necessary, especially in the case of the thermally expandable nonwoven fabric 5 described above, where the thermally expandable functional particles 4, 4 are solidified into ropes or clumps using synthetic resin to form large-diameter portions 2, 2 and integrated with long fibers, even increasing the amount of functional particles can suppress the decrease in air permeability of the nonwoven fabric. If the amount of functional particles is increased, the proportion of the large-diameter portions 2, 2 in the space of the thermally expandable nonwoven fabric 5 increases; however, if the large-diameter portions 2, 2 are ropes or clumps, even if the large-diameter portions are in contact with each other, space remains around them, which can suppress clogging of the gaps between fibers. In such a thermally expandable nonwoven fabric 5, even increasing the amount of functional particles can suppress the decrease in air permeability of the nonwoven fabric, allowing it to expand more rapidly in high-temperature air. Furthermore, when high-temperature air heats the nonwoven fabric by passing through it, the nonwoven fabric can expand uniformly from the inside.

[0102] Furthermore, as with the thermally expandable nonwoven fabric 5 described in the above embodiment, when the functional particles are surrounded by or bonded to the large-diameter portion by the synthetic resin in the form of a film, web, or fiber bundle, most of the functional particles are easily disposed near the surface of the long fiber large-diameter portion, and the synthetic resin separating the functional particles from the external air is extremely thin. Therefore, using high-temperature air, the thermally expandable functional particles are rapidly heated and expanded, and the thermally expandable nonwoven fabric 5 expands particularly quickly.

[0103] Furthermore, in the thermally expandable nonwoven fabric 5 of the above embodiment, the large-diameter portions 2, 2 of the long fibers contain thermally expandable functional particles 4, 4. Therefore, by simply stacking the long fibers, the functional particles 4, 4 can be dispersed substantially uniformly. That is, functional particles 4, 4 can be uniformly dispersed throughout the entire thickness direction of the nonwoven fabric. If such a thermally expandable nonwoven fabric is heated by passing hot air through it, the thermally expandable nonwoven fabric can be uniformly expanded.

[0104] Furthermore, in the thermally expandable nonwoven fabric 5, if the functional particles of thermal expansion are exposed to high-temperature air and expand, the large-diameter portions 2, 2 expand, and the space between the fibers decreases. Utilizing this effect, the thermally expandable nonwoven fabric 5 can be modified to reduce air permeability when heated. For example, if the thermally expandable nonwoven fabric 5 is placed in the ventilation holes of a ceiling, air can pass through the ventilation holes under normal conditions (when the air temperature is low). However, when high-temperature air passes through the ventilation holes due to an event such as a fire, the thermally expandable nonwoven fabric placed in the holes expands uniformly and rapidly, blocking the ventilation holes and thus limiting the air permeability. In other words, if the thermally expandable nonwoven fabric 5 is used in the ventilation holes and ventilation paths, air can pass through under normal conditions, and when it is necessary to prevent high-temperature air from escaping through the thermally expandable nonwoven fabric during an event such as a fire, air permeability can be limited or eliminated, preventing high-temperature air from escaping through the thermally expandable nonwoven fabric first. Figure 7 The same effect can be achieved by using the ventilation channels shown in the diagram.

[0105] Furthermore, similar to the thermally expandable nonwoven fabric 5, when the fiber diameter of the small-diameter portions 3, 3 is more than 1 / 100th of the diameter of the thermally expandable functional particles 4, 4, the disorder between the large-diameter and small-diameter portions can be suppressed. Due to the presence of the large-diameter portions 2, 2, gaps are easily generated when long fibers overlap, which improves the air permeability of the thermally expandable nonwoven fabric. Therefore, the thermally expandable nonwoven fabric can be expanded more rapidly and uniformly using high-temperature air.

[0106] Furthermore, as with the thermally expandable nonwoven fabric 5, when the diameter of the fibers in the small-diameter portion is 100 nanometers or more and 10 micrometers or less, and the diameter of the functional particles is 300 nanometers or more and 200 micrometers or less, it is possible to suppress the small-diameter portion from clogging the gaps between the large-diameter portions of the long fibers, thereby improving the air permeability of the thermally expandable nonwoven fabric. Therefore, it is possible to utilize high-temperature air to make the thermally expandable nonwoven fabric expand more rapidly and uniformly.

[0107] Furthermore, the above-described method for manufacturing thermally expandable nonwoven fabric, which includes a first step of melting the synthetic resin by heating it or dissolving it in a solvent to liquefy it, dispersing the thermally expandable functional particles into the liquefied synthetic resin; and a second step of spinning the liquefied synthetic resin containing the functional particles using a melt-blowing method or an electrospinning method to produce long fibers and then producing a nonwoven fabric, can effectively manufacture such thermally expandable nonwoven fabric.

[0108] Furthermore, if the thermally expandable nonwoven fabric 5 is manufactured using meltblown or electrospinning methods, during spinning, the small diameter portion 3, 3 is formed by drawing out the synthetic resin from the portion that should be the large diameter portion 2, 2. Therefore, less synthetic resin remains in the large diameter portion 2, 2, and the synthetic resin film covering the thermally expandable functional particles 4, 4 in the large diameter portion 2, 2 becomes thinner or forms a mesh. This makes it easier to exert thermal expansion more rapidly. For example, if the synthetic resin film covering the thermally expandable functional particles 4, 4 becomes thinner, the functional particles expand more rapidly upon contact with a high-temperature airflow.

[0109] Furthermore, especially when the synthetic resin is dissolved in a solvent to liquefy it and the long fibers are spun using electrospinning, spinning can be performed at a lower temperature. Therefore, even thermally expandable functional particles with low expansion start temperature (such as thermally expandable microcapsules) can be effectively integrated with the thermally expandable nonwoven fabric without causing the functional particles to expand during the nonwoven fabric manufacturing process.

[0110] The invention described above in relation to functional nonwoven fabrics with thermal expansion properties is not limited to the embodiments described above and can be implemented with various modifications. Other embodiments of the invention will be described below, focusing on the parts that differ from the embodiments described above, while detailed descriptions of the same parts are omitted. Furthermore, these embodiments can also be implemented by combining or substituting parts of each other.

[0111] For example, in the description of the above embodiments, the long fibers in the interwoven portion of the thermally expandable nonwoven fabric 5 were described as only contacting each other. However, in the interwoven portion, the long fibers can also be bonded together. For example, in the interwoven portion, the large diameter portions 2, 2 can be adhered to each other, or three or more (preferably four or more) small diameter portions 3, 3 can be externally connected to a large diameter portion. If such a structure is formed, the small diameter portions 3, 3 connect the large diameter portions 2, 2 into a mesh, which easily maintains the three-dimensional structure of the thermally expandable nonwoven fabric 5 and provides good air permeability.

[0112] Other embodiments of the thermally expandable nonwoven fabric 5 produced by changing manufacturing conditions, etc., are shown below. Figure 4 This is a microscope photograph showing the structure of the thermally expandable nonwoven fabric of Example 2, manufactured by changing the manufacturing conditions, etc. Compared with the above embodiment, the manufacturing conditions were adjusted to make the long fibers thicker overall. The synthetic resin is thermoplastic polyurethane resin (TPU), the functional particles are "NSF" (average particle size 5 micrometers), and the manufacturing process is the same as the above embodiment.

[0113] In the thermally expandable nonwoven fabric of Example 2, the diameter of the large-diameter portions 2, 2 is approximately 2 to 15 micrometers (average diameter 8 micrometers), and the diameter of the small-diameter portions 3, 3 is approximately 0.5 to 1.8 micrometers (average diameter 1.0 micrometer). Furthermore, in the nonwoven fabric of Example 2, it can also be seen that three or more small-diameter portions extend from the large-diameter portions in a branching manner.

[0114] Figure 5 This is a microscope photograph showing the structure of the thermally expandable nonwoven fabric of Example 3, manufactured by changing the manufacturing conditions, etc. Compared with the above-described example, the manufacturing conditions were adjusted after reducing the amount of functional particles. The synthetic resin is thermoplastic polyurethane resin (TPU), the functional particles are "NSF" (average particle size 5 micrometers), and the manufacturing process is the same as in the above-described example.

[0115] In the thermally expandable nonwoven fabric of Example 3, the diameter of the large-diameter portions 2, 2 is approximately 3 to 8 micrometers (average diameter 5 micrometers), and the diameter of the small-diameter portions 3, 3 is approximately 0.3 to 1.0 micrometers (average diameter 0.6 micrometers). Furthermore, even in the nonwoven fabric of Example 3, more than three small-diameter portions can be seen extending from the large-diameter portions in a branching manner.

[0116] The thermally expandable nonwoven fabrics in Examples 1, 2, and 3 all have appropriate air permeability, and when exposed to hot air (approximately 800°C), the functional particles expand, causing the thermally expandable nonwoven fabric to expand and form a heat insulation layer that is essentially non-breathable.

[0117] Furthermore, in the description of the above embodiments, a single-layer thermally expandable nonwoven fabric containing functional particles with thermal expansion properties was illustrated. However, the thermally expandable nonwoven fabric can also be a multi-layer thermally expandable nonwoven fabric having layers that do not contain functional particles. For example, a double-layer thermally expandable nonwoven fabric can be used, in which a web-like material made of aramid fibers is laminated on the aforementioned thermally expandable nonwoven fabric as a support layer.

[0118] The support layer is effective in improving the mechanical properties of thermally expandable nonwoven fabrics. In particular, if the support layer is constructed using fibers such as aramid fibers or metal fibers—materials with higher heat resistance than synthetic resins used as long fibers in thermally expandable nonwoven fabrics—the constraint on the functional particles, which is suppressed by the long fibers, can be easily released when exposed to high temperatures and causing the functional particles to expand. When a support layer is provided, it is particularly preferable to provide the support layer on the downstream side of the envisioned airflow.

[0119] In the description of the above embodiments, the case where the functional particles have thermal expansion properties has been explained; however, the functions of the functional particles are not limited to thermal expansion properties. For example, functional particles may also be particles that, in addition to having thermal expansion properties, also have water retention and water absorption properties. In this case, the water absorption of the nonwoven fabric can be improved, and a cooling effect can be generated by vaporizing the absorbed moisture.

[0120] In addition, functional particles can also be particles that, besides having thermal expansion properties, also have deodorizing and odor-removing functions. Thermally expandable nonwoven fabrics containing such functional particles can also be used for deodorizing and odor-removing applications. Furthermore, if fragrance-containing particles are used as functional particles, the thermally expandable nonwoven fabric can have a fragrance function.

[0121] In addition to thermal expansion, functional particles can also be particles that generate heat and absorb heat. Furthermore, functional particles can also be particles that, in addition to thermal expansion, also have thermal conductivity and electrical conductivity. Additionally, functional particles can also be particles that, in addition to thermal expansion, have the function of reacting with chemical substances present in the environment where thermally expandable nonwoven fabrics are used, or act as catalysts to promote reactions. In addition, functional particles can also be particles that, in addition to thermal expansion, also have optical functions such as light absorption, low reflection, fluorescence, reflectivity, and refraction.

[0122] Alternatively, the aforementioned thermally expandable nonwoven fabric can be formed by combining functional particles with thermally expandable properties with functional particles with other functions but without thermal expansion properties.

[0123] Furthermore, as a specific application of the thermally expandable nonwoven fabric, the above embodiment described its use in ventilation holes and ventilation channels in the ceiling of a building, where it expands and reduces the permeability of the ventilation holes during a fire; however, its application is not limited to this. For example, the thermally expandable nonwoven fabric can also be placed in structural components of a building, such as doors, window frames, and frames, in areas where fire resistance is required, to prevent the penetration of flames, burning, or damage to the components, thereby improving the fire resistance characteristics of the components.

[0124] Furthermore, for example, in the case of electrical components such as motors and inverters, wiring, cables, electronic circuits such as control circuits, integrated circuit boards, and electrical system components and elements such as power transistors, capacitors, and secondary batteries, cooling air is sometimes supplied to cool the circuits and components. However, if the ventilation duct of the cooling air is equipped with a thermally expandable nonwoven fabric as described above, cooling can be achieved through ventilation under normal circumstances. In addition, in the event of a fire in other parts of the system, it can prevent high-temperature air from being delivered to the object being cooled, and in the event of abnormal heating of the object being cooled, it can prevent high-temperature air from being delivered from the object being cooled, thereby improving the robustness of the system.

[0125] Furthermore, since the thermally expandable nonwoven fabric expands when exposed to hot air, it can also be used as an insulation material. Such an insulation material is lightweight and has good insulation properties.

[0126] Furthermore, the aforementioned thermally expandable nonwoven fabric can also be applied to other technical fields besides the uses of the thermally expandable nonwoven fabric exemplified in the above embodiments. For example, the thermally expandable nonwoven fabric integrated with functional particles that have deodorizing properties can be used for deodorizing purposes in rooms, etc. Industrial applicability

[0127] Functional nonwoven fabrics, for example, can be used for deodorization and have high industrial application value. Explanation of reference numerals in the attached figures:

[0128] 1. Functional nonwoven fabric 2 large diameter part 3. Small diameter section 4. Functional particles 5. Thermally Expandable Nonwoven Fabrics 9 ventilation channels

Claims

1. A functional nonwoven fabric comprising long fibers made of synthetic resin integrally formed of functional particles having a defined function, characterized in that, The functional particles are particles with thermal expansion properties. The long fibers have a diameter variation along their long side in a manner that alternates between multiple large-diameter and small-diameter portions. The small-diameter portion is a monofilament formed from the synthetic resin. At least a portion of the large-diameter portion contains the functional particles. The diameter of the fiber in the small diameter portion is less than or equal to the diameter of the functional particles contained in the large diameter portion.

2. The functional nonwoven fabric according to claim 1, characterized in that, At least a portion of the large-diameter portion is formed by solidifying a plurality of the functional particles into a rope or clump using the synthetic resin.

3. The functional nonwoven fabric according to claim 2, characterized in that, The diameter of the fiber in the small diameter portion is more than 1 / 100 of the diameter of the functional particle.

4. The functional nonwoven fabric according to claim 3, characterized in that, The diameter of the fiber in the small diameter section is 100 nanometers or more and 10 micrometers or less, and the diameter of the functional particles is 300 nanometers or more and 200 micrometers or less.

5. The functional nonwoven fabric according to claim 1, characterized in that, The functional particles are aluminum phosphite particles.

6. The functional nonwoven fabric according to claim 1, characterized in that, The functional nonwoven fabric is a functional nonwoven fabric with thermal expansion properties. The long fibers are configured to be arranged in a series of alternating large-diameter and small-diameter portions.

7. The functional nonwoven fabric according to claim 6, characterized in that, The functional particles are aluminum hydrogen phosphite particles.

8. The functional nonwoven fabric according to claim 6, characterized in that, The large-diameter portion is rope-like or clump-like. The functional particles are surrounded by or bonded to the synthetic resin in the form of a membrane, mesh, or fiber bundle, thereby becoming integrated with the large-diameter portion.

9. The functional nonwoven fabric according to claim 6, characterized in that, The diameter of the fiber in the small diameter portion is more than 1 / 100 of the diameter of the functional particle.

10. The functional nonwoven fabric according to claim 9, characterized in that, The diameter of the fiber in the small diameter section is 100 nanometers or more and 10 micrometers or less, and the diameter of the functional particles is 300 nanometers or more and 200 micrometers or less.

11. A method for manufacturing a functional nonwoven fabric, comprising manufacturing the functional nonwoven fabric according to any one of claims 1 to 10, characterized in that, The process includes the following steps: The first step involves heating the synthetic resin to melt it or dissolving it in a solvent to liquefy it, thereby dispersing the functional particles into the liquefied synthetic resin. as well as The second step, following the first step, involves spinning the liquid synthetic resin containing the functional particles using melt-blowing or electrospinning methods to produce long fibers, which are then used to make nonwoven fabric.

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