Method for forming a fibrous structure

Abstract

To form a fiber structure that maintains strength and allows obtaining a desired three-dimensional shape.SOLUTION: A method forms a fiber structure by heat welding a fiber assembly having a main fiber, a second fiber with a melting point lower by at least 80 degrees than a melting point of the main fiber, and a first fiber with a melting point lower by at least 40 degrees than the melting point of the main fiber and higher than the melting point of the second fiber. The method includes a first heating step to heat the fiber assembly at a temperature higher than the melting point of the second fiber and lower than the melting point of the first fiber, a cutting step to cut the fiber assembly into a prescribed shape, and a second heating step to dispose the cut fiber assembly in a mold and heat the fiber assembly at a temperature higher than the melting point of the first fiber and lower than the melting point of the main fiber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for forming a fibrous structure used in pillows, bedding mats, seats for various vehicles, cushions, and the like. [Background technology]

[0002] Conventionally, for fibrous structures such as pillows, bedding mats, seats for various vehicles, and cushions, methods have been proposed that involve filling a bag-shaped body with a filler such as cotton, or foamed polyurethane foam, which is molded into a predetermined shape by foaming polyurethane in a mold. However, with filler-based methods, the amount and unevenness of the filler during filling can make it difficult to achieve the desired three-dimensional shape. Furthermore, when using foamed polyurethane foam, there are problems such as poor breathability, a tendency to become stuffy, and an odor characteristic of foamed polyurethane.

[0003] To solve these problems, Patent Document 1 discloses a method for forming a desired fiber structure by placing a mixed fiber composed of polyester staple fibers and low-melting-point staple fibers having a melting point 40 degrees or more lower than that of the staple fibers into a mold and applying heat and pressure. In the molding method of Patent Document 1, the mixed fiber is first pre-fused under weak fusion conditions, the resulting mixed fiber sheet is cut into a shape corresponding to the mold, the cut sheets are stacked in the mold, compressed, and then fused together under strong fusion conditions greater than or equal to the weak fusion conditions to form a single unit. Weak fusion conditions refer to heating at a temperature between -20 degrees Celsius and less than +20 degrees Celsius from the melting point of the low-melting-point fibers, while strong fusion conditions refer to heating at a temperature between +10 degrees Celsius from the melting point of the low-melting-point staple fibers and less than or equal to the melting point of the polyester staple fibers. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-170259 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Low-melting-point short fibers melt when heated and move downward due to gravity as they cool and solidify. In the invention described in Patent Document 1, the mixed fibers are heated twice, and at least some of the low-melting-point short fibers melt twice. When low-melting-point short fibers melt so many times, they move downward, and the upper part of the fiber structure has fewer low-melting-point short fibers, which weakens the strength of the upper part in particular and makes it difficult to maintain its shape. In addition, because the low-melting-point short fibers undergo repeated melting and solidification, they deteriorate, and the fiber structure may become brittle, excessively hard, or have reduced elasticity, resulting in a structure that does not possess the desired properties.

[0006] This invention has been made in view of the above-mentioned problems, and aims to provide a method for forming a fiber structure in which low-melting-point fibers do not deteriorate, maintain strength, and can obtain a desired three-dimensional shape. [Means for solving the problem]

[0007] To achieve the above objectives, the present invention encompasses the subject matter described in the following sections.

[0008] Item 1: A method for forming a fiber structure by heat welding a fiber assembly comprising a main fiber, a second fiber having a melting point 80 degrees or more lower than the melting point of the main fiber, and a first fiber having a melting point 40 degrees or more lower than the melting point of the main fiber and higher than the melting point of the second fiber, A first heating step involves heating the fiber assembly at a temperature higher than the melting point of the second fiber and lower than the melting point of the first fiber. A cutting step of cutting the fiber aggregate into a predetermined shape, A method for forming a fiber structure, comprising: a second heating step of placing the cut fiber aggregate in a mold and heating it at a temperature higher than the melting point of the first fiber and lower than the melting point of the main fiber.

[0009] Item 2: A method for forming a fiber structure according to Request 1, wherein the main fiber is a polyester staple fiber, and the first and second fibers are heat-adhesive composite staple fibers made of a thermoplastic elastomer and polyester.

[0010] Item 3: The method for forming the fiber structure according to claim 1 or 2, wherein the fiber aggregate further includes a third fiber that is a fiber having no thermoadhesive property.

[0011] Item 4: A method for forming a fiber structure according to any one of items 1 to 3, comprising a plurality of fiber aggregates having different content ratios of the main fiber, the first fiber, and the second fiber, or a plurality of fiber aggregates having different types of at least one of the main fiber, the first fiber, and the second fiber, the first heating step of heating each of the fiber aggregates; the cutting step of cutting each of the fiber aggregates; and the second heating step of arranging and heating the cut fiber aggregates in the mold.

[0012] [[ID=1's]] the first heating step of heating each of the fiber aggregates; the step of overlapping the fiber aggregates; the cutting step of collectively cutting the overlapped fiber aggregates; and the second heating step of arranging and heating the overlapped and cut fiber aggregates in the mold.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a method for forming a fiber structure that can maintain strength and obtain a desired three-dimensional shape.

Brief Description of the Drawings

[0014] [Figure 1] It is a flowchart showing a method for forming a fiber structure according to an embodiment of the present invention. [Figure 2] The flowchart shows other embodiments. [Figure 3] The flowchart shows other embodiments. [Figure 4] (A) is a plan view of the pillow, which is a fibrous structure, and (B) is a cross-sectional view along line AA of (A). [Figure 5] (A) is a plan view of the pillow, which is a fibrous structure, and (B) is a cross-sectional view along line BB of (A). [Figure 6] (A) is a plan view of the pillow, which is a fibrous structure, and (B) is a cross-sectional view along line CC of (A). [Figure 7] (A) is a plan view of the pillow, which is a fibrous structure, and (B) is a cross-sectional view along the DD line of (A). [Figure 8] (A) is a plan view of the cushion, which is a fibrous structure, and (B) is a cross-sectional view along the EE line of (A). [Figure 9] This is a perspective view of a cushion, which is a fibrous structure. [Figure 10] This is a perspective view of a cushion, which is a fibrous structure. [Modes for carrying out the invention]

[0015] Embodiments of the present invention will be described with reference to the drawings. The fiber structure is formed by heat welding a fiber aggregate comprising a main fiber, a second fiber whose melting point is 80 degrees or more lower than the melting point of the main fiber, and a first fiber whose melting point is 40 degrees or more lower than the melting point of the main fiber and higher than the melting point of the second fiber. Unless otherwise specified, "fiber aggregate" refers to an aggregate of fibers comprising a main fiber, a first fiber, and a second fiber, and in this specification includes the aggregate before the first heating step, the aggregate after the first heating step, the aggregate after cutting in the cutting step, and the aggregate after the second heating step that constitutes the fiber structure.

[0016] The main fibers are welded together by the first and second fibers to form the framework of the fiber structure, and in this embodiment, the main fibers are polyester staple fibers. In this embodiment, the melting point of the main fibers is set to be between 200 degrees Celsius and 330 degrees Celsius. The content ratio of the main fibers to the fiber aggregate is set to be between 25% by weight and 65% by weight. "By weight" is sometimes simply written as "%".

[0017] The main fiber, a polyester staple fiber, is more preferably a polyester fiber such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, poly-1,4-dimethylcyclohexane terephthalate, polyethylene naphthalate, polytrimethylene naphthalate, polybutylene naphthalate, polypivalolactone, polylactic acid (PLA), or stereocomplex polylactic acid. In addition to polyester fibers, staple fibers containing polyolefin homopolymers or copolymers of various olefins, or blends (mixtures) of such staple fibers, or composite staple fibers consisting of two or more of the above thermoplastic resin components can also be preferred. The composite form of the composite fiber may be a core-sheath type composite fiber, a side-by-side type composite fiber, or a sea-island type composite fiber. The thermoplastic resin may also contain, as needed, colorants, various stabilizers, UV absorbers, thickening and branching agents, matting agents, and various other modifiers. Of these short fibers, short fibers containing polyalkylene terephthalate or polyalkylene naphthalate are preferred from the viewpoint of ease of recycling and fiber formation properties, and short fibers containing polyethylene terephthalate are particularly preferred. The main fiber may also contain nylon fibers that have moisture absorption and release properties.

[0018] The main fiber may be a crimped short fiber, with a crimp count of 3 to 40 per 2.54 cm, preferably 7 to 15 per 2.54 cm.

[0019] In the crimped short fibers described above, the single fiber diameter is preferably in the range of 7 to 170 μm. The single fiber cross-sectional shape (cross-section perpendicular to the fiber axis) of the crimped short fibers may be a normal round cross-section, or it may be a non-standard cross-section such as a triangle, square, flattened ellipse, star shape, or a shape having one or more hollow holes in these cross-sectional shapes. When the single fiber cross-sectional shape is non-standard, the single fiber diameter shall be the diameter of its circumscribed circle. Furthermore, in the case of a round hollow cross-section, the outer diameter shall be measured. The fiber length of the crimped short fibers is preferably in the range of 30 to 150 mm. More preferably, it is in the range of 40 to 80 mm. Even more preferably, it is in the range of 50 to 75 mm.

[0020] The first fiber is a heat-adhesive composite short fiber, and at least a portion of it is composed of a heat-adhesive component having a melting point at least 40 degrees lower than the melting point of the main fiber and higher than the melting point of the second fiber, so that at least a portion of its surface melts upon heating and can weld to the main fiber, the second fiber, and the first fiber itself. The melting point of the heat-adhesive component of the first fiber (also called the "melting point of the first fiber") is preferably 180 degrees or less, greater than 100 degrees, more preferably 170 degrees or less, greater than 150 degrees, and more preferably 160 degrees. The content ratio of the first fiber to the fiber aggregate is set to 20% by weight or more and 55% by weight or less.

[0021] Examples of thermoplastic resins used as the heat-bonding component for the first fiber include polyurethane elastomers, polyester elastomers, non-elastic polyester homopolymers and their copolymers, polyolefin homopolymers and their copolymers, and polyvinyl alcohol polymers.

[0022] Polyurethane elastomers are thermoplastic resins obtained by reacting a low-melting-point polyol with a number-average molecular weight of approximately 500 to 6000, an organic diisocyanate with a molecular weight of 500 or less, and a chain extender with a molecular weight of 500 or less. Among the above compounds, low-melting-point polyols with a number-average molecular weight of approximately 500 to 6000 include, for example, dihydroxy polyethers, dihydroxy polyesters, dihydroxy polycarbonates, and dihydroxypolyesteramides. Organic diisocyanates with a molecular weight of 500 or less include, for example, p,p'-diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, 2,6-diisocyanate methyl caproate, and hexamethylene diisocyanate. Chain extenders with a molecular weight of 500 or less include, for example, glycols, amino alcohols, or triols.

[0023] Among these thermoplastic resins, particularly preferred are polyurethanes using polytetramethylene glycol, poly-ε-caprolactone, or polybutylene adipate as low-melting-point polyols. Examples of organic diisocyanate compounds in this case include compounds obtained by replacing the dihydroxyl groups of p,p'-bishydroxyethoxybenzene and 1,4-butanediol with isocyanate groups.

[0024] Furthermore, the polyester elastomer is a polyether ester copolymer obtained by copolymerizing a thermoplastic polyester as the hard segment and poly(alkylene oxide) glycol as the soft segment. More specifically, it is preferable to use at least one compound of dicarboxylic acid selected from the group consisting of aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, or diphenyl-4,4'-dicarboxylic acid, alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, tricyclodecanedicarboxylic acid, or adamantanedicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, or dimer acid, or ester-forming derivatives thereof, as the dicarboxylic acid component constituting the thermoplastic polyester. Furthermore, it is preferable to use at least one compound of diol components selected from the group consisting of aliphatic diols such as 1,4-butanediol, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentyl glycol, or decamethylene glycol, alicyclic diols such as 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, or tricyclodecanemethanol, or ester-forming derivatives thereof, as the diol component (dihydroxy compound component) constituting the thermoplastic polyester. In addition, it is preferable to use at least one compound of dicarboxylic acid selected from the group consisting of polyethylene glycol, poly(1,2- and 1,3-polypropylene oxide) glycol, poly(tetramethylene oxide) glycol, copolymers of ethylene oxide and propylene oxide, copolymers of ethylene oxide and tetrahydrofuran, etc., with a number average molecular weight of about 400 to 5000, as the poly(alkylene oxide) glycol that forms the soft component. It is preferable to use a ternary copolymer obtained by polymerization of these compounds using methods commonly practiced by those skilled in the art as a polyester elastomer.

[0025] In particular, block copolymer polyether esters are preferred in terms of adhesion, temperature characteristics, and strength, with polybutylene terephthalate or polyhexamethylene terephthalate as the hard component and polyoxybutylene glycol (polytetramethylene glycol) as the soft segment. In this case, the polyester portion constituting the hard segment is polybutylene terephthalate, where the main acid component is terephthalic acid and the main diol component is butylene glycol. Of course, a portion of this acid component (usually 30 mol% or less) may be substituted with other dicarboxylic acid components or oxycarboxylic acid components, and similarly, a portion of the glycol component (usually 30 mol% or less) may be substituted with diol components other than butylene glycol. Furthermore, the polyether portion constituting the soft segment may be a polyether substituted with dioxy components other than butylene glycol.

[0026] As non-elastic copolymerized polyester homopolymers and their copolymers, it is preferable to use polyesters obtained by copolymerizing aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, suberic acid, or sebacic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, or naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid, or tricyclodecanedicarboxylic acid with aliphatic or alicyclic diols such as diethylene glycol, trimethylene glycol, 1,2-propylene glycol, tetramethylene glycol, polyethylene glycol, or paraxylene glycol in predetermined proportions. Furthermore, copolymerized esters to which oxy acids such as parahydroxybenzoic acid are added as desired can also be mentioned. Specifically, for example, a polyester copolymerized in which terephthalic acid and isophthalic acid are present as the dicarboxylic acid component in a ratio of 30 / 70 to 70 / 30 mol%, and ethylene glycol and diethylene glycol are present as the diol component in a ratio of 90 / 10 to 10 / 90 mol%, is preferably used.

[0027] Examples of polyolefin polymers include low-density polyethylene, high-density polyethylene, polypropylene, polystyrene, polyacrylic acid, polymethyl methacrylate, polyvinyl acetate, and modified polyolefins thereof.

[0028] Among the above-mentioned heat-bonding components, copolymerized polyester polymers are particularly preferred. Furthermore, the thermoplastic resin may also contain various stabilizers, UV absorbers, thickening and branching agents, matting agents, colorants, and other various modifiers as needed.

[0029] In the first fiber, the counterpart component of the heat-bonding component is preferably an inelastic polyester as described above. More specifically, polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate (polybutylene terephthalate), polyethylene naphthalate, polytrimethylene naphthalate, and polytetramethylene naphthalate. In this case, it is preferable that the thermoplastic resin constituting the heat-bonding component occupies at least half the surface area of ​​the surface of the heat-bondable composite short fiber. The weight ratio of the heat-bonding component and the counterpart component is preferably in the range of 90 / 10 to 10 / 90 in terms of composite ratio. More preferably, the composite ratio is in the range of 70 / 30 to 30 / 70, and even more preferably, it is in the range of 60 / 40 to 40 / 60. By setting the numerical range within this range, the fibers possess sufficient strength, elastic modulus, and flexibility, and heat treatment allows for the formation of heat-welded bonding points with sufficient strength between the heat-adhesive composite short fibers, or between the heat-adhesive composite short fibers and crimped short fibers. The form of the heat-adhesive composite short fibers is not particularly limited, but it is preferable that the heat-adhesive component and the opposing component be side-by-side, core-sheath, or sea-island type composite fibers, and more preferably a core-sheath type composite fiber. In this core-sheath type heat-adhesive composite short fiber, the heat-adhesive component becomes the sheath and the opposing component becomes the core, which may be concentric (concentric core-sheath type composite short fiber) or eccentric (eccentric core-sheath type composite short fiber). A composite short fiber employing a core-sheath type composite form, with the heat-adhesive component positioned in the sheath, is preferable because heat treatment allows for the formation of heat-welded bonding points with sufficient strength between the heat-adhesive composite short fibers and / or between the heat-adhesive composite short fibers and crimped short fibers in an intersecting state.

[0030] In heat-adhesive composite short fibers, the single fiber diameter is preferably in the range of 15 to 50 μm. More preferably, it is in the range of 20 to 40 μm, and even more preferably, in the range of 24 to 30 μm. Such heat-adhesive composite short fibers are preferably cut to a fiber length of 3 to 100 mm. More preferably, it is in the range of 10 to 60 mm.

[0031] The second fiber is a heat-adhesive composite short fiber, and at least a portion of it is composed of a heat-welding component. The melting point of the heat-welding component is set to a temperature 80 degrees lower or lower than the melting point of the main fiber, and 120 degrees lower or higher than the melting point of the main fiber. The second fiber is a short fiber that, upon heating, melts at least a portion of its surface and can weld to the main fiber, to other second fibers, and to the first fiber. The melting point of the heat-welding component of the second fiber (also called the "melting point of the second fiber") is preferably set to 170 degrees or lower and 60 degrees or higher, more preferably to 140 degrees or lower and 90 degrees or higher, and even more preferably to 120 degrees or lower and 110 degrees or higher. The content ratio of the second fiber to the fiber aggregate is set to 5% by weight or more and 20% by weight or less. The other components are the same as those of the first fiber, so their description is omitted.

[0032] (Method for forming a fibrous structure) Next, the method for forming the fibrous structure will be explained with reference to Figure 1. First, a web formation process is performed. In the web formation process (ST10), the main fiber, first fiber, and second fiber are placed in a stirrer in a predetermined weight ratio, and these fibers are stirred and mixed. A carding machine is then used to obtain a sheet-like fiber (web) with the fiber direction aligned. The sheet-like web has a roughly rectangular shape when viewed from above, but other shapes are also possible. The thickness of the web is set so that the thinnest part is 10 gsm (grams per square meter), the thickest part is 80 gsm, and the average value is 35 gsm.

[0033] Next, a lamination process (ST11) is performed. In the lamination process, multiple webs obtained in the web formation process are stacked in the thickness direction (height direction) to form a fiber aggregate with a desired thickness. The thickness direction (height direction) refers to the direction perpendicular to the mounting surface when the fiber structure is placed on the mounting surface. In this embodiment, the fiber aggregate is rectangular in shape, but the shape is not limited. If a web (fiber aggregate) of the desired size can be obtained in the web formation process, the lamination process may be omitted. Alternatively, the webs may be stacked in the transverse direction (parallel to the mounting surface and not intersecting the mounting surface) instead of the thickness direction.

[0034] Next, the first heating step (ST12) is performed. In the first heating step, the fiber assembly is heated at a temperature higher than the melting point of the second fiber and lower than the melting point of the first fiber. The heating method is not particularly limited, and known heating devices can be used. The heating temperature is set to 180 degrees or less and 60 degrees or more, more preferably 140 degrees or less and 100 degrees or more, and even more preferably 120 degrees or less and 110 degrees or more. The heating time is set to 45 seconds or more and 90 seconds or less, more preferably 60 seconds.

[0035] The first heating process melts the heat-welding components of the second fibers. In the first heating process, the heat-welding components of the first fibers do not melt, and the proportion of the second fibers in the fiber aggregate is small. Therefore, the fiber aggregate is in a temporarily welded state. Temporary welding refers to a state of welding that is such that the fiber aggregate does not fall apart when a worker carries it, but is not strong enough to allow the fiber structure to be used as a pillow, cushion, mattress, etc.

[0036] Next, the cutting process (ST13) is performed. The fiber aggregate, which has been integrated by the first heating process, is cut into a predetermined shape and size according to the mold. The cutting method is not particularly limited; for example, a cutting machine may be used.

[0037] Next, a second heating step (ST14) is performed. In the second heating step, the cut fiber aggregate is placed in a mold and heated at a temperature higher than the melting point of the first fiber and lower than the melting point of the main fiber. The heating method is not particularly limited, and known heating devices can be used. The heating temperature is set to 220 degrees or less and 100 degrees or more, more preferably 180 degrees or less and 140 degrees or less, and even more preferably 160 degrees. The heating time is set to 25 seconds or more and 85 seconds or less, more preferably 45 seconds.

[0038] In the second heating step, the heat-welding components of the second and first fibers melt, and the fiber aggregate is integrally welded with the first, second, and main fibers, forming a fibrous structure through heat welding. Furthermore, by shaping the mold to the desired form, the fibrous structure is formed to the desired shape.

[0039] According to this embodiment, the fiber aggregate comprises a main fiber, a first fiber, and a second fiber, and is formed as a fiber structure through two heating processes, a first heating process and a second heating process, with the main fiber being welded to the first and second fibers. Since the first fiber is melted only in the second heating process, it is less likely to move downward compared to the conventional method where it is melted multiple times. This prevents the first fiber from decreasing in the upper part of the fiber structure, which can lead to weakened strength in the upper part and difficulty in maintaining its shape. Furthermore, since the first fiber is melted only in the second heating process, it is less likely to deteriorate compared to the conventional method where low-melting-point fibers repeatedly melt and solidify. As a result, the fiber structure is more likely to maintain desired strength, elasticity, and other properties.

[0040] In this embodiment, the heat-welding component of the second fiber melts in each of the first and second heating steps, and therefore moves downward due to gravity after each of the first and second heating steps. However, by reducing the content ratio of the second fiber to the extent that the fiber aggregate is only partially welded, the amount of downward movement is reduced. As a result, the upper part of the fiber structure is sufficiently composed of first fibers, and the strength is less likely to weaken.

[0041] Furthermore, the system is equipped with first and second fibers with different melting points, and the second fibers melt sufficiently during the first heating process, ensuring that the fiber aggregate is reliably pre-welded. As a result, when the operator moves the fiber aggregate after the first heating process or performs the next cutting process, the fiber aggregate does not collapse, making the work easier.

[0042] (Other embodiments) Other embodiments of the present invention are shown. In this embodiment, the fiber aggregate further includes third fibers containing fibers that do not have heat-adhesion properties, and this fiber aggregate is heat-welded to form a fiber structure. Unlike the first and second fibers, the third fibers do not contain heat-welding components that melt in the first and second heating steps. Examples of the third fibers include polyester, synthetic fibers, hemp, cotton-based natural cellulose fibers, natural animal hair fibers such as sheep and alpaca, regenerated fibers such as rayon and lyocell, and nylon fibers with moisture absorption and release properties. The content ratio of the third fibers to the fiber aggregate is preferably 5% by weight or more and 30% by weight or less, and more preferably 10% by weight or more and 20% by weight or less. In the first heating step, the melting of the second fibers allows the fiber structure to be temporarily welded. Other configurations and methods for forming the fiber structure are the same as in the embodiment of Figure 1, so their description is omitted.

[0043] If the third fiber is a natural cellulose fiber with particularly high hygroscopic properties, the fiber structure can be given the function of absorbing moisture such as sweat. Furthermore, if the third fiber is a natural animal hair fiber, the fiber structure can be given the function of retaining heat.

[0044] (Other embodiments) Other embodiments of the present invention will now be described. In the method for forming the fiber structure of this embodiment, a plurality of (for example, two) fiber assemblies A and B are heat-welded together. Each fiber assembly A and B may have the same main fiber, first fiber, and second fiber material, but the weight ratio of these materials may differ. In addition, each fiber assembly A and B may use different materials for at least one of the main fiber, first fiber, and second fiber.

[0045] Figure 2 shows the method for forming the fiber structure of this embodiment. The webing process (ST20), lamination process (ST21), first heating process (ST22), and cutting process (ST23) are performed individually for each fiber assembly A and B. In the second heating process (ST24), the cut fiber assemblies A and B are stacked in a mold and heated. This forms a fiber structure in which multiple fiber assemblies are stacked as layers. The other fiber structures and formation methods are the same as in the embodiment of Figure 1, so their description is omitted.

[0046] According to the above embodiment, each fiber assembly A and B has a different ratio of main fiber, first fiber, and second fiber content, or different types of materials are used for the main fiber, first fiber, and second fiber, so that the functions of each fiber assembly A and B can be made different. For example, in a fiber structure, the hardness of the part consisting of fiber assembly A may be made hard, and the hardness of the part consisting of fiber assembly B may be made soft.

[0047] Alternatively, as shown in Figure 3, the web formation process (ST30), lamination process (ST31), and first heating process (ST32) may be performed individually for each fiber assembly A and B, followed by a process of overlapping each fiber assembly (ST33). Subsequently, in the cutting process (ST34), the overlapped fiber assemblies A and B may be cut together, and in the second heating process (ST35), the overlapped and cut fiber assemblies A and B may be placed in a mold and heated.

[0048] (Examples) Examples of fiber structures manufactured by the method for forming fiber structures of the present invention are shown in Tables 1 to 3. Examples 1 to 8 use the fiber structure as a pillow 10, and details are shown in Table 1. Note that the pillow 10 may be covered with a cover (not shown) when in use.

[0049] The pillow 10, which is a fiber structure of Example 1, has a roughly rectangular shape when viewed from above, as shown in Figures 4(A) and 4(B), with length, width, and height set to 40 cm, 60 cm, and 12 cm, respectively. As shown in Figure 4(B), both ends are formed in a convex shape that curves outward when viewed from the side. The fiber assembly 11 includes a main fiber, a first fiber, and a second fiber. The first and second fibers are made of thermoplastic elastomer and polyester, which are heat-adhesive composite short fibers, and the main fiber is a 15D polyester fiber. "D" stands for "denier". The main fiber is also composed of a single-hole hollow fiber or a solid fiber. The weight ratio of the first fiber, second fiber, and main fiber is 45%, 10%, and 45%. The density of the fiber structure is 1600 g / m². 2 Therefore, the hardness of the pillow 10 is high. The pillow 10 of Example 1 is made using the method shown in Figure 1.

[0050] "Hardness" refers to how easily the shape and state of a fiber structure change when force is applied. "High" hardness means that the shape and state do not change easily, and when the head is placed on the pillow 10, the height of the head rest area is 90% or more of the height when the head is not resting on it. "Low" hardness means that the shape and state change easily, and when the head is placed on the pillow 10, the height of the head rest area is 60% or less of the height when the head is not resting on it. "Medium" hardness means that the ease of changing shape and state is between "high" and "low," and when the head is placed on the pillow 10, the height of the head rest area is greater than 60% of the height when the head is not resting on it, but less than 90%.

[0051] In the following descriptions of Examples 2 to 8, only the differences from Example 1 will be explained. Example 2 uses 6D polyester fiber with mite-repellent properties as the main fiber. This imparts mite-repellent properties to the pillow 10. The weight ratios of the first fiber, second fiber, and main fiber are 40%, 10%, and 50%, and the density of the fiber structure is 1200 g / m². 2 The firmness of pillow 10 is medium.

[0052] Example 3 differs from Example 1 in its content ratio. The weight ratios of the first fiber, second fiber, and main fiber are 35%, 10%, and 55%, and the density of the fiber structure is 1200 g / m². 2 The firmness of the pillow 10 will be medium. In Example 3, in the second heating step, the woven fabric may be placed on the upper and lower surfaces of the fiber aggregate 11, and the woven fabric may be attached to the fiber structure.

[0053] Example 4 contains a fiber aggregate 11 comprising a main fiber, a first fiber, a second fiber, and a third fiber. The main fiber is a 3D polyester fiber, and the third fiber is linen. The weight ratios of the first fiber, second fiber, main fiber, and third fiber are 45%, 5%, 25%, and 30%. The density of the fiber structure is 1000 g / m³. 2 The pillow 10 has a medium firmness. Because it uses linen, a natural fiber, as the third fiber, the pillow 10 has moisture-absorbing and releasing properties, making it less prone to stuffiness.

[0054] Example 5 contains a fiber aggregate 11 comprising a main fiber, a first fiber, a second fiber, and a third fiber. The main fiber is a 3D polyester fiber, and the third fiber is lyocell. The weight ratios of the first fiber, second fiber, main fiber, and third fiber are 35%, 10%, 25%, and 30%. The density of the fiber structure is 1200 g / m³. 2 The firmness of pillow 10 is medium. Because it uses lyocell, a regenerated cellulose fiber, as the third fiber, pillow 10 has moisture absorption and release properties, making it less prone to stuffiness. In addition, since the regenerated cellulose fiber is made from natural materials, it is less irritating to the skin.

[0055] The pillow 10, a fibrous structure shown in Example 6, has a rectangular planar shape and a semi-elliptical cross-section that is convex upwards, as shown in Figures 5(A) and 5(B). It is used with its flat bottom surface placed on a support surface. As seen from the plane in Figure 5(A), the length and width are 20 cm and 60 cm, and the height, i.e., the distance from the support surface to the highest point, is 12 cm. The pillow 10 is made of two fibrous aggregates 11A and 11B that are heat-welded together. In the cross-sectional view shown in Figure 5(B), the side surface of the fibrous aggregate 11B, which is the core layer, is covered by the fibrous aggregate 11A, which is the outer layer.

[0056] The outer layer, fiber aggregate 11A, contains a main fiber, a first fiber, a second fiber, and a third fiber. The main fiber is a 3D polyester fiber, and the third fiber is lyocell. The weight ratios of the first fiber, second fiber, main fiber, and third fiber are 30%, 5%, 35%, and 30%. The density of the fiber aggregate 11A when the fiber structure is formed is 1200 g / m³. 2 The hardness is medium. The core layer, fiber aggregate 11B, contains main fibers, first fibers, and second fibers. The main fibers are 15D polyester fibers. The weight ratio of the first fibers, second fibers, and main fibers is 35%, 10%, and 55%. The density of the fiber aggregate 11B when the fiber structure is formed is 1600 g / m³ 2 The hardness is high. Pillow 10 of Example 6 is made using the method shown in Figure 2.

[0057] In Example 6, the user rests their head on the outer layer, which has a medium firmness, so the user does not feel that the pillow 10 is too hard. Furthermore, because the central layer has a high firmness, the pillow 10 does not sink too much when the user rests their head on it.

[0058] The pillow 10, which is a fiber structure as shown in Example 7, has a rectangular planar shape, as shown in Figures 6(A) and 6(B). In its cross-sectional shape, convex portions 12 and 13 are formed on both upper ends in the width direction, and a recess 14 is formed in the center. The convex portion 13 on the other side is formed to be taller than the convex portion 12 on the other side, with a height of 12 cm. In one example, the user uses the pillow 10 by resting their neck on the shorter convex portion 12 and their head on the recess 14. The pillow 10 is made of two fiber assemblies 11A and 11B that are heat-welded together. In the cross-sectional view shown in Figure 6(B), the outer fiber assembly 11A covers the entire perimeter of the core fiber assembly 11B, and the fiber assembly 11B is not exposed to the outside.

[0059] The fiber aggregate 11A that is the outer layer includes a main fiber, a first fiber, a second fiber, and a third fiber. The main fiber is a 3D polyester fiber, and the third fiber is lyocell. The content ratios by weight ratio of the first fiber, the second fiber, the main fiber, and the third fiber are 35%, 10%, 25%, and 30%. The density of the fiber aggregate 11A when the fiber structure is formed is 1200 g / m 2 , and the hardness is medium. The fiber aggregate 11B that is the core layer includes a main fiber, a first fiber, and a second fiber. The main fiber is a 15D polyester fiber. The content ratios by weight ratio of the first fiber, the second fiber, and the main fiber are 45%, 10%, and 45%. The density of the fiber aggregate 11B when the fiber structure is formed is 1600 g / m 2 , and the hardness is high. The pillow 10 of Example 7 is created using the method shown in FIG. 2.

[0060] In the pillow 10 of Example 7, since the user places their head on the outer layer with medium hardness, the user does not feel that the pillow 10 is too hard, and because the hardness of the central layer is high, the pillow 10 does not sink too much even when the user places their head on it.

[0061] The pillow 10, which is the fiber structure shown in Example 8, has a rectangular parallelepiped shape as shown in FIGS. 7(A) and 7(B). The pillow 10 is formed by thermally welding three fiber aggregates 11A to 11C, and the fiber aggregates 11A to 11C are laminated in the height direction. The thickness (height) of each layer is equal, and in Example 8, it is set to 4 cm each.

[0062] The fiber aggregate 11A that is the upper layer in FIG. 7(B) includes a main fiber and a first fiber. The main fiber is a 3D polyester fiber, and the content ratios by weight ratio of the first fiber and the main fiber are 30% and 7%. The density of the fiber aggregate 11A when the fiber structure is formed is 1000 g / m 2 , and the hardness is low. The fiber aggregate 11B that is the middle layer includes a main fiber, a first fiber, and a second fiber. The main fiber is a 15D polyester fiber. The content ratios by weight ratio of the first fiber, the second fiber, and the main fiber are 55%, 5%, and 40%. The density of the fiber aggregate 11B when the fiber structure is formed is 1600 g / m 2The hardness is high. The upper layer, fiber aggregate 11C, contains main fibers and first fibers. The main fibers are 3D polyester fibers, and the weight ratio of first fibers to main fibers is 40% and 60%. The density of fiber aggregate 11C when the fiber structure is formed is 1000 g / m³ 2 The hardness is low. Pillow 10 of Example 8 is made using the method shown in Figure 2.

[0063] [Table 1]

[0064] Examples 9-13 use the fiber structure as a mattress (not shown), and details are shown in Table 2. Note that the mattress may be covered with a cover during use. The mattress, which is the fiber structure of Example 9, has a roughly rectangular shape when viewed from the plane, with width, length, and height set at 100cm, 200cm, and 8cm, respectively. The fiber assembly 11 includes a main fiber, a first fiber, and a second fiber. The first and second fibers are made of thermoplastic elastomer and polyester, which are heat-adhesive composite short fibers, and the main fiber is a 15D polyester fiber. The weight ratio of the first fiber, second fiber, and main fiber is 45%, 10%, and 45%. The density of the fiber structure is 2500 g / m². 2 The mattress is firm, and is harder than the pillow 10 of Example 1. The mattress of Example 9 is made using the method shown in Figure 1.

[0065] In the following descriptions of Examples 10-13, only the differences from Example 9 will be explained. Example 10 has a height of 12 cm, and the weight ratios of the first fiber, second fiber, and main fiber are 25%, 10%, and 65%. The density of the fiber structure is 1600 g / m³. 2 Therefore, the mattress is firm.

[0066] The mattress shown in Example 11 has fiber aggregates 11A, 11B, and 11C, which form the upper, middle, and lower layers, stacked sequentially in the height direction. The height of the mattress is 12 cm, and the heights of the fiber aggregates 11A, 11B, and 11C are each 4 cm. The upper fiber aggregate 11A contains main fibers and first fibers, and the main fibers are 3D polyester fibers. The weight ratio of the first fibers and main fibers is 30% and 70%, respectively. The density of the fiber aggregate 11A when the fiber structure is formed is 1000 g / m³ 2 The hardness is low. The middle layer, fiber aggregate 11B, contains a main fiber, a first fiber, and a second fiber. The main fiber is a 15D polyester fiber. The weight ratio of the first fiber, second fiber, and main fiber is 35%, 10%, and 55%. The density of the fiber aggregate 11B when the fiber structure is formed is 1600 g / m³ 2 The hardness is high. The lower fiber aggregate 11C has the same structure as the upper fiber aggregate 11A, so its description is omitted. The mattress of Example 11 is made using the method shown in Figure 2.

[0067] The mattress shown in Example 12 has upper and lower fiber aggregates 11A and 11B stacked in the height direction. The height of the mattress is 12 cm, and the heights of fiber aggregates 11A and 11B are 6 cm each. The upper fiber aggregate 11A contains a main fiber, a first fiber, a second fiber, and a third fiber. The main fiber is a 3D polyester fiber, and the third fiber is lyocell. The weight ratios of the first fiber, second fiber, main fiber, and third fiber are 25%, 10%, 35%, and 30%. The density of fiber aggregate 11A when the fiber structure is formed is 1200 g / m³. 2 The hardness is medium. The lower layer, fiber aggregate 11B, contains a main fiber, a first fiber, and a second fiber. The main fiber is a 15D polyester fiber. The weight ratio of the first fiber, second fiber, and main fiber is 35%, 10%, and 55%. The density of the fiber aggregate 11B when the fiber structure is formed is 1600 g / m³ 2 The hardness is high. The mattress of Example 12 is made using the method shown in Figure 2.

[0068] The mattress shown in Example 13 has five layers stacked in order in the height direction: a surface layer, a pressure distribution layer, a core layer, another pressure distribution layer, and fiber aggregates 11A to 11E, which form the surface layer. The height of the mattress is 12 cm, the heights of fiber aggregates 11A, 11B, 11D, and 11E are each 2 cm, and the height of fiber aggregate 11C, which forms the core layer, is 4 cm. Fiber aggregate 11A, which forms the surface layer, contains a main fiber, a first fiber, a second fiber, and a third fiber. The main fiber is a 3D polyester fiber, and the third fiber is lyocell. The weight ratios of the first fiber, second fiber, main fiber, and third fiber are 25%, 10%, 35%, and 30%, respectively. The density of fiber aggregate 11A when the fiber structure is formed is 200 g / m³. 2 Its hardness is low, and it is considerably softer than the other layers. The fiber aggregate 11B, which is the pressure-distributing layer, contains two types of main fibers and a first fiber. One of the main fibers is an ultrafine polyester fiber of 0.8D, and the other main fiber is a polyester fiber of 2D. The weight ratio of the first fiber, the one main fiber, and the other main fiber is 30%, 30%, and 40%. The density of the fiber aggregate 11B when the fiber structure is formed is 500 g / m³ 2 Its hardness is low; it is harder than the surface fiber aggregate 11A but softer than the core layer, which will be described later. The core layer, fiber aggregate 11C, contains a main fiber, a first fiber, and a second fiber. The main fiber is a 15D polyester fiber. The weight ratios of the first fiber, second fiber, and main fiber are 35%, 10%, and 55%. The density of the fiber aggregate 11C when the fiber structure is formed is 1200 g / m³. 2 The hardness is medium. The structure of the fiber aggregate 11D, which is the pressure-distributing layer, is the same as that of the fiber aggregate 11B, which is the pressure-distributing layer, and the structure of the fiber aggregate 11E, which is the surface layer, is the same as that of the fiber aggregate 11A, so their explanations are omitted. The mattress of Example 12 is made using the method shown in Figure 2.

[0069] Please note that the mattress is not limited to the sizes mentioned above; it may be a standard size such as single, semi-double, double, queen, or king.

[0070] [Table 2]

[0071] Examples 14 to 16 use a fiber structure as a cushion 20, and details are shown in Table 3. The cushion may be covered when in use. The sheet cushion, which is a fiber structure of Example 14, has a circular shape when viewed from above, with a diameter of 40 cm, as shown in Figure 8(A). The center is the highest point when viewed from above, with a height of 6 cm at the highest point. The sheet cushion 20 is composed of upper and middle fiber assemblies 11A and 11B, with the upper fiber assemblies 11A and 11B at the highest point each having a thickness of 3 cm. As shown in Figure 8(B), the middle fiber assembly 11B has a semi-elliptical cross-section that is convex upwards, and the upper surface of the fiber assembly 11B is covered by the upper fiber assembly 11A.

[0072] The upper layer, fiber aggregate 11A, contains main fibers and first fibers. The first fibers are heat-adhesive composite short fibers made of thermoplastic elastomer and polyester, while the main fibers are 3D polyester fibers. The weight ratio of the first fibers to the main fibers is 30% and 70%. The density of the fiber aggregate 11A when the fiber structure is formed is 1000 g / m³. 2 The hardness is low. The intermediate fiber aggregate 11B contains a main fiber, a first fiber, and a second fiber. The first and second fibers are heat-adhesive composite short fibers made of thermoplastic elastomer and polyester, while the main fiber is a 15D polyester fiber. The weight ratios of the first fiber, second fiber, and main fiber are 40%, 10%, and 50%. The density of the fiber aggregate 11B when the fiber structure is formed is 1600 g / m³. 2 The hardness is high. The cushion of Example 14 is made using the method shown in Figure 2.

[0073] The cushion 20 of Example 15 is primarily used against the user's back or waist, and as shown in Figure 9, the side portions 22 are formed to be thicker (higher) than the central portion 21. The cushion 20 has a width and length of 33 cm and 33 cm, with a height of 10 cm at the highest point and a height of approximately 2.5 cm at the lowest point. The fiber assembly 11 includes a main fiber, a first fiber, and a second fiber. The first and second fibers are made of thermoplastic elastomer and polyester, which are heat-adhesive composite short fibers, and the main fiber is a 15D polyester fiber. The weight ratio of the first fiber, second fiber, and main fiber is 35%, 10%, and 55%. The density of the fiber structure is 1400 g / m². 2 The cushion 20 has a medium hardness. The cushion 20 of Example 15 is made using the method shown in Figure 1.

[0074] As shown in Figure 10, the cushion 20 of Example 16 has a depression 24 formed in the center of the longitudinal direction of the main body 23, and a projection 25 protruding from the center of one side edge along the longitudinal direction of the main body 23. The cushion 20 has a width of 59 cm and a length of 29 cm, respectively, with a height of 11 cm at the highest point and a height of approximately 4 cm at the lowest point. The fiber assembly 11 includes a main fiber, a first fiber, and a second fiber. The material of the first fiber and the second fiber is a heat-adhesive composite short fiber made of thermoplastic elastomer and polyester, and the main fiber is a 15D polyester fiber. The weight ratio of the first fiber, second fiber, and main fiber is 20%, 20%, and 60%. The density of the fiber structure is 1000 g / m². 2 Therefore, the hardness of cushion 20 is low. The cushion 20 of Example 16 is made using the method shown in Figure 1.

[0075] [Table 3]

[0076] Examples 1 to 16 described above were pillows 10, mattresses, and cushions 20, but the fiber structure may also be used as bedding mats, seats for various vehicles, and cushions, and the shape is not limited to the above examples, and any desired shape can be formed depending on the mold. In addition, there may be one fiber assembly 11, or multiple fiber assemblies 11 may be stacked in the height direction. The number of stacked fiber assemblies 11 is not particularly limited, and may be four layers, five or more layers.

[0077] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention. The dimensions, materials, shapes, relative arrangements, etc. of the components described or shown in the drawings as embodiments are not intended to limit the scope of the present invention, but are merely illustrative examples. For example, expressions that describe relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only describe such arrangements strictly, but also describe states in which there are tolerances or relative displacements of an angle or distance sufficient to obtain the same function. For example, expressions that describe things being in an equal state such as "identical," "equal," and "homogeneous" should not only describe states in which they are strictly equal, but also describe states in which there are tolerances or differences sufficient to obtain the same function. For example, expressions that describe shapes such as square shapes or cylindrical shapes should not only describe geometrically precise shapes such as square shapes or cylindrical shapes, but also describe shapes including uneven parts and chamfered parts to the extent that the same effect can be obtained. The expressions "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components. [Explanation of symbols]

[0078] 10 Pillow (Fiber structure) 11 (11A~11C) Fiber aggregate 20 cushions

Claims

1. A method for forming a fiber structure by heat welding a fiber assembly comprising a main fiber, a second fiber having a melting point 80 degrees or more lower than the melting point of the main fiber, a first fiber having a melting point 40 degrees or more lower than the melting point of the main fiber and higher than the melting point of the second fiber, and a third fiber made of a different material from the main fiber, A first heating step involves heating the fiber aggregate at a temperature higher than the melting point of the second fiber and lower than the melting point of the first fiber. A cutting step of cutting the fiber aggregate into a predetermined shape, The process includes a second heating step in which the cut fiber assembly is placed in a mold and heated at a temperature higher than the melting point of the first fiber and lower than the melting point of the main fiber, The aforementioned third fiber does not have heat-bonding properties and is one of the following: natural cellulose fiber, natural animal hair fiber, regenerated fiber, or nylon fiber. A method for forming a fibrous structure.

2. A method for forming a fiber structure according to claim 1, wherein the main fiber is a polyester staple fiber, and the first fiber and the second fiber are heat-adhesive composite staple fibers made of a thermoplastic elastomer and polyester.

3. The collection comprises a plurality of fiber assemblies having different content ratios of the main fiber, the first fiber, the second fiber, and the third fiber, or a plurality of fiber assemblies having different types of at least one of the main fiber, the first fiber, the second fiber, and the third fiber, The first heating step involves heating each of the aforementioned fiber assemblies, The cutting step involves cutting each of the aforementioned fiber aggregates, A method for forming a fiber structure according to claim 1, comprising a second heating step of stacking and heating each of the cut fiber assemblies in the mold.

4. The collection comprises a plurality of fiber assemblies having different content ratios of the main fiber, the first fiber, the second fiber, and the third fiber, or a plurality of fiber assemblies having different types of at least one of the main fiber, the first fiber, the second fiber, and the third fiber, The first heating step involves heating each of the aforementioned fiber assemblies, The process of stacking each of the aforementioned fiber assemblies, The cutting step involves cutting each of the superimposed fiber assemblies together, A method for forming a fiber structure according to claim 1, comprising a second heating step of placing the overlapping and cut fiber assemblies into the mold and heating them.

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