JP5180020B2 - Bulky fiber structure and cushioning material - Google Patents

Description

  The present invention relates to a structure (nonwoven fiber structure) having a non-woven fiber structure that is lightweight, bulky, highly breathable, and excellent in cushioning and flexibility, a method for producing the structure, and the non-woven fabric The present invention relates to a cushion material composed of a fiber structure (bulky fiber structure).

  Conventionally, non-woven fabrics composed of natural fibers or synthetic fibers have bulkiness and lightness, and are used not only for sanitary or medical applications such as disposable diapers and wet wipers, clothing applications, but also for cushioning materials and sound absorbing materials. Widely used in applications. For example, urethane foam or the like is used as a cushioning material for furniture, bedding, vehicles, etc., but depending on the application, the elasticity is too strong, the texture is not sufficient, and the air permeability is low. On the other hand, the nonwoven fabric is excellent in flexibility, such as a needle punched nonwoven fabric and a hot air type thermal bond nonwoven fabric, and also excellent in texture and breathability. However, the nonwoven fabric is not sufficient in cushioning properties and shape stability and has a problem of fiber dropping. Therefore, developments for improving these drawbacks have been carried out in the use of nonwoven fabrics utilizing cushioning properties.

For example, as a non-woven fabric for use in sanitary materials such as diapers, household items such as wiping, and filters, JP 2006-241642 (Patent Document 1) has a polytrimethylene terephthalate polymer disposed in the core. An airlaid nonwoven fabric comprising 50% by weight or more of heat-adhesive core-sheath composite short fibers in which a fiber-forming thermoplastic polymer having a melting point or softening point of 60 to 180 ° C. is arranged in the sheath part, and the basis weight is 10 to 10%. A bulky soft air laid nonwoven fabric having 300 g / m ² , a density of 0.02 to 0.07 g / cm ³ , and a bending resistance of 4 to 8 cm is disclosed. In this document, a non-woven fabric is produced by airlaid using a specific heat-bondable fiber and dispersed in the air. Is manufactured.

  However, when a nonwoven fabric having a large thickness is produced by such an airlaid method, the uniformity of adhesion in the thickness direction is lowered, the cushioning property is not sufficient, and the cushioning property is easily lowered when repeatedly used. Furthermore, this nonwoven fabric has low rigidity and cannot be used for applications requiring strength.

JP-A-2001-207366 (Patent Document 2) discloses a non-elastic crimped short fiber and a polymer having a melting point lower by 40 ° C. or more than the polymer constituting the non-elastic crimped short fiber. The heat-adhesive composite short fibers disposed on the surface of the heat-bonded composite short fibers were mixed so that the weight ratio was 90/10 to 50/50, and the heat-adhesive composite short fibers were heat-sealed in a state where the heat-adhesive composite short fibers intersected each other. Fixing points and a fiber structure in which the heat-bonding composite short fibers and the inelastic crimped short fibers intersect with each other and heat-bonded fixing points are scattered, and the average density of the fiber structures Is in the range of 0.02 to 0.20 g / cm ³ and the total number of fibers arranged parallel to the thickness direction of the fiber structure is (B), and the thickness direction of the fiber structure The total number of fibers arranged perpendicularly to (A ), A sound absorbing fiber structure having a B / A of 1.5 or more is disclosed. In this document, a heat-fused fiber structure is manufactured by heating at 200 ° C. while folding a web in which the heat-adhesive composite short fibers and the inelastic crimped short fibers are folded into an accordion shape. Yes.

However, since this fiber structure also has non-uniform fiber adhesion in the thickness direction and the fibers are oriented in the thickness direction, the strength such as rigidity and breaking strength in the plane direction is low. Further, this document does not describe details of crimping of inelastic crimped short fibers.
JP 2006-241642 A (Claim 1, paragraphs [0002] and [0034], Examples) JP 2001-207366 A (Claim 1, paragraph [0027], Example)

  Accordingly, an object of the present invention is to provide a non-woven fiber structure excellent in cushioning property and form stability (holding property) without impairing the properties of a flexible and bulky nonwoven fabric and a method for producing the same.

  Another object of the present invention is to provide a non-woven fiber structure and a method for producing the same, which can prevent the fibers from falling off and retain cushioning properties and form even after repeated use.

  Still another object of the present invention is to provide a non-woven fiber structure having a light weight and a low density and having an appropriate rigidity or rigidity and a method for producing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have heat-treated the heat-adhesive fiber and the crimped fiber having a relatively large crimp with high-temperature steam, and appropriately use the heat-adhesive fiber. When the web is fused, the fibers are gently entangled with each other, and the crimped fibers having a large crimp are entangled so as to surround other fibers, and a bulky fiber structure having a uniform adhesive state in the thickness direction is obtained. The obtained fiber structure was found to be excellent in cushioning properties and form stability (holding property) without impairing the properties of the flexible and bulky nonwoven fabric.

That is, the bulky fiber structure of the present invention has a non-woven fiber structure formed by entanglement of heat-adhesive fibers and fibers containing crimped fibers having an average curvature radius of 0.3 to 2 mm, and A bulky fiber structure in which fibers are fixed by fusing, and a step of forming a fiber including a heat-adhesive fiber and a crimped fiber, and a heat-humidification treatment of the generated fiber web with high-temperature steam for melting And 25% by mass or more of the heat-adhesive fibers with respect to the entire structure, and in the thickness direction in the cross section in the thickness direction. The fiber adhesion rate in each divided area is 0.5 to 10%, and the adhesion points of the fibers fused by the heat-adhesive fibers are distributed substantially uniformly. An average curvature radius of the crimped fiber is about 0.5 to 1 mm, and the crimped fiber is composed of a polyalkylene arylate resin and a modified polyalkylene arylate resin. It may be a fiber. The heat-adhesive fiber has a melting point or softening point of 50 to 150 ° C., a sheath portion made of a wet heat-adhesive resin or a hydrophobic heat-adhesive resin, and a heat having a higher melting point or softening point than the heat-adhesive resin. It may be a core-sheath type composite fiber formed with a core part made of a plastic resin. The ratio (mass ratio) of the thermoadhesive fiber and the crimped fiber is about the former / the latter = 90/10 to 30/70. The bulky fiber structure of the present invention has a fiber curvature rate of 1.1 or more in each region divided in three in the thickness direction in the cross section in the thickness direction, and the maximum value of the fiber curvature rate in each region The ratio of the minimum value is 75% or more, the fiber adhesion rate in each region is 2 to 10%, and the ratio between the maximum value and the minimum value of the fiber adhesion rate in each region is 50. % Or more. Moreover, the bulky fiber structure of the present invention has an apparent density of 0.01 to 0.1 g / cm ³ , an air permeability of 50 to 400 cm ³ / (cm ² · sec) according to the Frazier method, and is thermally conductive. 25% in the recovery behavior with respect to 25% compression stress in the compression behavior in the behavior in which the rate is 0.03 to 0.07 W / m · K and compressed to 50% in accordance with JIS K6400-2 The compressive stress ratio may be 30% or more. Furthermore, the bulky fiber structure of the present invention has a surface hardness of 8 to 80 by an FO type durometer, a compressibility with respect to a load of 0.5 g / m ² is 60% or more, and JIS K6400-4. Repeated compression residual strain test The return rate after repeated compression based on the method B (constant displacement method) may be 75% or more.

  According to the present invention, there is provided a bulky fiber structure including a step of forming a fiber including a heat-adhesive fiber and a crimped fiber, and a step of heat-humidifying the produced fiber web with high-temperature steam for fusing. A manufacturing method is also included.

  In the present invention, inside the fiber structure, the fibers are gently entangled with each other, and the crimped fibers having a large crimp are entangled so as to surround other fibers and have a uniform adhesive state in the thickness direction. It is excellent in cushioning properties and form stability (holding property) without impairing the properties of the flexible and bulky nonwoven fabric. Further, the fiber is prevented from falling off, and the cushioning property and form can be maintained even after repeated use. Furthermore, it is lightweight and has a low density, and has an appropriate rigidity or rigidity.

[Bulky fiber structure]
The bulky fiber structure (or non-woven fiber assembly) of the present invention includes a heat-adhesive fiber and crimped fibers having an average curvature radius of 0.3 to 2 mm, and the heat-adhesive fiber is inside the structure. While fusing substantially uniformly, the fibers are entangled gently so that the crimped fibers surround the other fibers. As will be described in detail later, this bulky fiber structure exhibits high-temperature (overheated or heated) water vapor on the web containing the heat-adhesive fibers and the crimped fibers, thereby expressing the adhesive action of the heat-adhesive fibers. It can be obtained by partially bonding the fibers together. That is, in the bulky fiber structure of the present invention, the strength of the structure is expressed by fusion with the heat-adhesive fiber, and the cushioning property and flexibility of the structure are expressed by entanglement with the crimped fiber. . Furthermore, the bulky fiber structure of the present invention is bonded with a small amount of adhesion points while keeping moderately small voids by point adhesion or partial adhesion of heat-adhesive fibers, and the fibers are also entangled with each other. The fiber is prevented from falling off, and has high flexibility and shape retention.

(Thermo-adhesive fiber)
In the present invention, since the point bonding is performed between the fibers that intersect with the heat-adhesive fibers softened by high-temperature steam, the fibers can be flexibly bonded to each other efficiently even though the bonding area is small. Both stability and compatibility can be achieved.

  The thermoadhesive fiber is composed of at least a thermoadhesive resin. The heat-adhesive resin only needs to be able to flow or be easily deformed by high-temperature steam and exhibit an adhesive function. Specifically, a thermoplastic resin that is softened with high-temperature steam (for example, about 80 to 130 ° C., particularly about 90 to 120 ° C.) and can be self-adhered or bonded to other fibers, for example, 80 to 130 ° C. (for example, 85 A thermoplastic resin having a melting point or softening point of ˜125 ° C., preferably 90-120 ° C., more preferably about 95-115 ° C. can be used. When the melting point or softening point exceeds 130 ° C., the resin becomes insufficiently softened, and the adhesiveness of the fiber is lowered. On the other hand, when the temperature is lower than 80 ° C., the water-insoluble thermoplastic resin melts and flows due to the heat of water vapor, fills the voids of the fibers and lowers the air permeability. Further, once fused, it is difficult to solidify with the heat remaining in the fiber, and productivity and the like are also reduced.

  Further, the thermoplastic resin (thermoadhesive resin) having such a melting point or softening point includes a wet heat adhesive resin having a high affinity for high temperature steam and a hydrophobic thermoadhesive resin having a low affinity for high temperature steam. It is. Both can be bonded with high-temperature steam, but for example, when a resin with the same melting point is treated with the same high-temperature steam, there is a difference that the wet heat adhesive resin is more strongly bonded, depending on the application. Can be selected as appropriate. For example, when it is desired to easily produce a relatively hard fiber structure, wet heat adhesive fibers may be used. On the other hand, when it is desired to produce a fiber structure with high water repellency from the hygienic aspect, hydrophobic thermal adhesive fibers may be used.

The wet heat adhesive resin, for example, C _1-3 alkyl celluloses such as cellulose-based resins (methyl cellulose, hydroxy C _1-3 alkyl celluloses such as hydroxypropyl cellulose, carboxy C _1-3 alkyl cellulose or salt thereof such as carboxymethyl cellulose ), Polyalkylene glycol resins (poly C _2-4 alkylene oxides such as polyethylene oxide and polypropylene oxide), polyvinyl resins (polyvinyl pyrrolidone, polyvinyl ether, vinyl alcohol polymers, polyvinyl acetals, etc.), acrylic copolymers And salts thereof (such as copolymers containing units composed of acrylic monomers such as (meth) acrylic acid and (meth) acrylamide or alkali metal salts thereof), modified vinyl copolymers (isobutyrate) A copolymer of a vinyl monomer such as lene, styrene, ethylene, vinyl ether and an unsaturated carboxylic acid such as maleic anhydride or an anhydride thereof, or a salt thereof), a polymer in which a hydrophilic substituent is introduced ( And polyesters introduced with a sulfonic acid group, a carboxyl group, a hydroxyl group, etc., polyamide, polystyrene, or a salt thereof), aliphatic polyester resins (polylactic acid resins, etc.). Furthermore, among polyolefin resins, polyester resins, polyamide resins, polyurethane resins, thermoplastic elastomers or rubbers (such as styrene elastomers), it can be softened at the temperature of hot water (high-temperature steam) to exhibit an adhesive function. Other resins are also included.

These wet heat adhesive resins can be used alone or in combination of two or more. The wet heat adhesive resin is usually composed of a hydrophilic polymer or a water-soluble resin. Among these wet heat adhesive resins, vinyl alcohol polymers such as ethylene-vinyl alcohol copolymers, polylactic acid resins such as polylactic acid, (meth) acrylic copolymers containing (meth) acrylamide units, A vinyl alcohol polymer containing an α-C _2-10 olefin unit such as ethylene or propylene, particularly an ethylene-vinyl alcohol copolymer is preferred.

  In the ethylene-vinyl alcohol copolymer, the ethylene unit content (copolymerization ratio) is, for example, about 10 to 60 mol%, preferably about 20 to 55 mol%, and more preferably about 30 to 50 mol%. When the ethylene unit is in this range, a unique property of having wet heat adhesiveness but not hot water solubility is obtained. If the proportion of the ethylene units is too small, the ethylene-vinyl alcohol copolymer easily swells or gels with low-temperature steam (water), and its form is likely to change only once wetted with water. On the other hand, when the ratio of the ethylene unit is too large, the hygroscopicity is lowered, and fiber fusion due to wet heat is difficult to be exhibited, so that it is difficult to ensure practical strength. When the ratio of the ethylene unit is particularly in the range of 30 to 50 mol%, the processability into a sheet or plate is particularly excellent.

  The saponification degree of the vinyl alcohol unit in the ethylene-vinyl alcohol copolymer is, for example, about 90 to 99.99 mol%, preferably 95 to 99.98 mol%, more preferably 96 to 99.97 mol%. Degree. When the degree of saponification is too small, the thermal stability is lowered, and the stability is lowered by thermal decomposition or gelation. On the other hand, if the degree of saponification is too large, it is difficult to produce the fiber itself.

  Although the viscosity average degree of polymerization of an ethylene-vinyl alcohol-type copolymer can be selected as needed, it is 200-2500, for example, Preferably it is 300-2000, More preferably, it is about 400-1500. When the degree of polymerization is within this range, the balance between spinnability and wet heat adhesion is excellent.

  Examples of the hydrophobic heat-adhesive resin include polyolefin resins, acrylic resins, styrene resins, polyester resins, polyamide resins, polyurethane resins, and the like. These hydrophobic hot melt resins can be used alone or in combination of two or more. Among these hydrophobic hot melt resins, polyolefin resins (for example, polyethylene resins such as polyethylene and ethylene-propylene copolymers), polyester resins (for example, amorphous copolyester having low crystallinity, poly Polyester elastomers having an oxyalkylene glycol unit), polyamide resins (for example, aliphatic polyamides such as polyamide 12, semi-aromatic polyamides synthesized from aromatic dicarboxylic acids and aliphatic diamines, etc.) are widely used. . In particular, in order to reduce the melting point or softening point of the homopolymer, the amorphous property has a lower crystallinity than the homopolymer by copolymerizing and modifying the copolymerizable monomer. A copolymer may also be used. As the amorphous copolymer, an amorphous polyester resin is preferable from the viewpoint of excellent adhesiveness and fiber characteristics.

Amorphous polyester resins include copolyesters containing alkylene arylate units as a main component, and in particular, C _2-6 alkylene arylate units (for example, C _2-4 alkylene terephthalate units such as polyethylene terephthalate and polybutylene terephthalate). ) As a main component, and a copolyester containing other copolymerization component (modifier) is preferred.

Examples of the diol component in the other copolymerization component include poly C _2-4 alkylene glycol (eg, diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene glycol), C _2-8 alkylene glycol ( For example, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, etc.), alicyclic diol (eg, cyclohexane-1,4-dimethanol, etc.) and the like can be mentioned. . These diol components can be used alone or in combination of two or more. Of these diol components, poly C _2-4 alkylene glycol (particularly diethylene glycol) is preferred as a copolymer component for poly C _2-4 alkylene terephthalate resins such as polyethylene terephthalate.

Examples of the dicarboxylic acid component in the other copolymerizable component, for example, C _6-12 aliphatic dicarboxylic acid (e.g., adipic acid, C _6-12 aliphatic dicarboxylic acids such as sebacic acid), an aromatic dicarboxylic acid [for example, Phthalic acid, isophthalic acid, 5-sodium sulfoisophthalic acid, naphthalene-2,6-dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, bis (carboxyphenyl) ethane and the like. These dicarboxylic acid components can be used alone or in combination of two or more. Of these copolymer components, as a copolymer component (modifier) for a poly C _2-4 alkylene terephthalate resin such as polyethylene terephthalate, an asymmetric aromatic dicarboxylic acid such as isophthalic acid or phthalic acid (especially isophthalic acid) is preferable. .

The ratio of the other copolymerization component can be selected from the range of, for example, about 1 to 50 mol%, for example, 2 to 40 mol%, preferably 3 to 30 mol%, more preferably, with respect to the corresponding all monomer components. May be about 5 to 25 mol%. In particular, when the other copolymer component is a dicarboxylic acid such as isophthalic acid, it is, for example, 1 to 50 mol%, preferably 3 to 40 mol%, more preferably 5 to 35 mol%, based on the total dicarboxylic acid component. It may be about (especially 10 to 30 mol%). When the other copolymerization component is a diol component such as diethylene glycol, for example, 0.1 to 30 mol%, preferably 0.5 to 20 mol%, more preferably 1 to 15 mol%, based on the total diol component It may be about (especially 2 to 10 mol%). Specific examples of the amorphous polyester-based resin include poly C _2-4 alkylene terephthalate modified products such as isophthalic acid-modified polyethylene terephthalate from the viewpoint of physical properties, quality of fibers, productivity of fiber forming process, cost, and the like. General purpose.

  Amorphous polyester-based resins can be branched using a polyvalent carboxylic acid component such as trimellitic acid or pyromellitic acid, or a polyol component such as glycerin, trimethylolpropane, trimethylolethane, or pentaerythritol as necessary. You may let them.

  The cross-sectional shape (cross-sectional shape perpendicular to the length direction of the fiber) of the heat-adhesive fiber is a general solid cross-sectional shape, such as a round cross-section or an irregular cross-section [flat, elliptical, polygonal, 3-14 Leaf shape, T-shape, H-shape, V-shape, dogbone (I-shape, etc.)], and may be a hollow cross-section. A heat-bondable fiber is a composite fiber composed of a plurality of resins including at least a heat-bondable resin from the viewpoint of improving the mechanical properties of the fiber and maintaining a bulky non-woven fiber structure after fusion. May be. The composite fiber only needs to have a heat-adhesive resin on at least a part of the fiber surface. From the viewpoint of adhesiveness, the heat-adhesive resin has at least a part of the surface in the length direction (particularly the entire surface). It is preferable to occupy continuously.

  Examples of the cross-sectional structure of the composite fiber in which the heat-adhesive fiber occupies the surface include a core-sheath type, a sea-island type, a side-by-side type, a multi-layer bonding type, a radial bonding type, and a random composite type. Of these cross-sectional structures, the core-sheath structure (that is, the sheath part is heat-adhesive) is a structure in which the heat-adhesive resin continuously occupies the entire surface in the length direction because it is a structure with high adhesiveness. A core-sheath structure made of resin is preferred. In such a core-sheath type composite fiber, by using a fiber that does not melt or soften with high-temperature steam as the core, the core component maintains the fiber form even when treated with high-temperature steam, thus maintaining the fiber structure before treatment. it can.

  The fibers constituting such a core part may be inorganic fibers such as glass fiber, carbon fiber, metal fiber, etc., but the points such as flexibility and affinity with the heat-adhesive resin constituting the sheath part Therefore, a fiber composed of a thermoplastic resin having a higher melting point or softening point than the above-mentioned thermoadhesive resin (particularly, ethylene-vinyl alcohol copolymer or amorphous polyester resin) is preferable. The melting point or softening point higher than that of the heat-adhesive resin is, for example, a melting point of 160 ° C. or higher, preferably 160 to 300 ° C., more preferably about 170 to 280 ° C.

  As such a thermoplastic resin, for example, a thermoplastic resin constituting a crimped fiber, which will be described later, can be used, among which a polyolefin resin, a (meth) acrylic resin, a vinyl chloride resin, a styrene resin, Polyester resins, polyamide resins, polycarbonate resins, polyurethane resins, thermoplastic elastomers, cellulose resins and the like are widely used. These thermoplastic resins can be used alone or in combination of two or more.

Among these thermal adhesive resins, from the viewpoint of heat resistance and dimensional stability, for example, polypropylene resin (for example, polypropylene), polyester resin [polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, Poly C _2-4 alkylene arylate resins such as polyethylene naphthalate], polyamide resins (aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 610, polyamide 10, polyamide 12, polyamide 6-12), in particular, A polyethylene terephthalate-based resin such as PET is preferable from the viewpoint of excellent balance between heat resistance and fiber-forming properties.

  Furthermore, these thermoplastic resins may be composed of the same type or the same type of thermoplastic resin as the thermoadhesive resin forming the sheath portion from the viewpoint of improving the adhesion between the sheath portion and the core portion. For example, when the sheath component is amorphous polyester, the core component may be a polyester resin such as polyethylene terephthalate.

  In a core-sheath type composite fiber composed of a sheath part composed of a thermoadhesive resin and a core part composed of a thermoplastic resin having a melting point or softening point higher than that of the thermoadhesive resin, the core-sheath ratio (Mass ratio) is, for example, core / sheath = 90/10 to 10/90, preferably 80/20 to 15/85, and more preferably about 60/40 to 20/80. If the ratio of the sheath part composed of the heat-adhesive resin is too large, it is difficult to ensure the strength of the fiber, and if the ratio of the sheath part is too small, the heat-adhesive resin exists continuously in the length direction of the fiber surface. It becomes difficult to make it, and thermal adhesiveness falls.

  The average fineness of the heat-adhesive fiber can be selected, for example, from the range of about 0.01 to 100 dtex, preferably 0.1 to 50 dtex, more preferably 0.5 to 30 dtex (particularly 1 to 10 dtex), depending on the application. Degree. When the average fineness is within this range, the balance between the strength of the fiber and the expression of thermal adhesiveness is excellent.

  The average fiber length of the heat-adhesive fiber can be selected from a range of, for example, about 10 to 100 mm, preferably 20 to 80 mm, and more preferably about 25 to 75 mm (particularly 35 to 55 mm). When the average fiber length is within this range, the fibers are sufficiently entangled, so that the mechanical strength of the fiber structure is improved.

  The crimp rate of the heat-bondable fibers is, for example, about 1 to 50%, preferably 3 to 40%, more preferably 5 to 30% (particularly 10 to 20%). The number of crimps is, for example, about 1 to 100 pieces / 25 mm, preferably about 5 to 50 pieces / 25 mm, and more preferably about 10 to 30 pieces / 25 mm.

(Crimped fiber)
The crimped fiber has a substantially coiled (spiral or helical spring-shaped) three-dimensional crimp. The average radius of curvature of a circle formed by this crimped fiber coil (crimped coil portion) is in the range of 0.3-2 mm, for example, 0.4-1.5 mm, preferably 0.5-1. The thickness is about 2 mm (for example, 0.5 to 1 μm), more preferably about 0.6 to 1 mm (particularly 0.6 to 0.8 μm). Here, the average radius of curvature is an index representing the average size of a circle formed by a coil of crimped fibers, and in the present invention, the crimped fibers having such a relatively large crimp are bonded to the heat bond. By gently tangling so as to surround the conductive fibers and by fusing with the heat-adhesive fibers, the gaps between the fibers are appropriately maintained.

  The number of crimps of the crimped fiber is, for example, 5 pieces / 25 mm or more (for example, 5-50 pieces / 25 mm), preferably 8-30 pieces / 25 mm, more preferably about 10-20 pieces / 25 mm. May be.

  The cross-sectional shape of the crimped fiber (cross-sectional shape perpendicular to the length direction of the fiber) is a general solid cross-sectional shape such as a round cross-section or an irregular cross-section [flat, elliptical, polygonal, 3-14 leaf shape , T-shape, H-shape, V-shape, dogbone (I-shape, etc.), and may be a hollow cross-section, but is usually a round cross-section.

  The average fineness of the crimped fiber can be selected from a range of, for example, about 0.1 to 100 dtex, for example, 0.5 to 50 dtex, preferably 1 to 30 dtex, more preferably 2 to 20 dtex (particularly 3 to 10 dtex). is there. If the fineness is too thin, it is difficult to produce the fiber itself, and it is difficult to secure the fiber strength. On the other hand, if the fineness is too thick, the fiber becomes rigid and the flexibility is lowered.

  The average fiber length of the crimped fibers can be selected from a range of, for example, about 10 to 100 mm, preferably 20 to 80 mm, and more preferably about 25 to 75 mm (particularly 40 to 70 mm). If the fiber length is too short, the formation of the fiber web becomes difficult, and the entanglement of the fibers by the crimped fibers becomes insufficient, and it becomes difficult to ensure strength and stretchability. If the fiber length is too long, it is difficult to form a fiber web having a uniform basis weight.

The crimped fiber may be an inorganic fiber, but is preferably an organic fiber, particularly a fiber made of a thermoplastic resin, from the viewpoint of flexibility and lightness. Examples of the thermoplastic resin include polyolefin resins (medium density or high density polyethylene, poly C _2-4 olefin resins such as polypropylene) and acrylic resins (acrylonitrile units such as acrylonitrile-vinyl chloride copolymer). Acrylonitrile resin), polyvinyl acetal resin (polyvinyl acetal resin, etc.), polyvinyl chloride resin (polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylonitrile copolymer, etc.), polyvinylidene chloride Resin (vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-vinyl acetate copolymer, etc.), styrene resin (heat resistant polystyrene, etc.), polyester resin (polyethylene terephthalate resin, polytrimethylene terephthalate resin, polybutylene) Poly C _2-4 alkylene arylate resins such as terephthalate resin and polyethylene naphthalate resin), polyamide resins (polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, etc. aliphatic polyamide resins) , Semi-aromatic polyamide resins, polyphenylene isophthalamide, polyhexamethylene terephthalamide, poly-p-phenylene terephthalamide and other aromatic polyamide resins), polycarbonate resins (bisphenol A type polycarbonate, etc.), polyparaphenylene benzobis Examples thereof include oxazole resins, polyphenylene sulfide resins, polyurethane resins, and cellulose resins (such as cellulose esters).

  Among these resins, in the present invention, the softening point or melting point is higher than the temperature of the above-mentioned high-temperature steam because it is not melted or softened even when heated and humidified with high-temperature steam to cause fusion due to crimped fibers. A thermoplastic resin having, for example, a polypropylene resin, a polyester resin, or a polyamide resin is preferable, and an aromatic polyester resin or a polyamide resin is particularly preferable from the viewpoint of excellent balance of heat resistance, fiber forming property, and the like. In the present invention, the resin exposed on the surface of the crimped fiber is preferably a fiber composed of such a thermoplastic resin so that the fusion by the crimped fiber does not occur even when treated with high-temperature steam.

  The crimped fiber may be a fiber having an asymmetric or layered (so-called bimetal) structure crimped by heating due to a difference in thermal contraction rate (or thermal expansion rate) of a plurality of resins. A plurality of resins usually have different softening points or melting points. As the cross-sectional structure of the composite fiber having a bimetal structure, a phase separation structure formed of a plurality of resins, for example, a core-sheath type, a sea-island type, a blend type, a parallel type (side-by-side type or multilayer bonding type), and a radial type (Radial bonding type), hollow radiation type, block type, random composite type and the like can be mentioned. Of these cross-sectional structures, a structure in which the phase portions are adjacent (so-called bimetal structure) and a structure in which the phase separation structure is asymmetric, for example, an eccentric core-sheath type and a parallel type structure are preferable. The crimped fibers may be latently crimpable fibers, that is, crimps may be expressed by treatment with high-temperature steam in the production process of the fiber structure, but productivity, coil uniformity, etc. In view of this, it is preferable to use a fiber that has been crimped in advance by heat treatment or the like.

  The plurality of resins may have different heat shrinkage rates, and may be a combination of resins of the same system or a combination of different resins. In this invention, it is preferable that it is comprised with the combination of resin of the same type | system | group from the point of adhesiveness. In the case of a combination of resins of the same system, a combination of a component (A) that forms a homopolymer (essential component) and a component (B) that forms a modified polymer (copolymer) is usually used. In other words, the homopolymer that is an essential component is crystallized more than the homopolymer by, for example, copolymerizing and modifying a copolymerizable monomer that lowers the crystallinity, melting point, or softening point. The melting point or the softening point may be lowered as compared with the homopolymer. Thus, a difference may be provided in the thermal shrinkage rate by changing the crystallinity, melting point or softening point. The difference in melting point or softening point may be, for example, about 5 to 150 ° C, preferably about 50 to 130 ° C, and more preferably about 70 to 120 ° C. The ratio of the copolymerizable monomer used for the modification is, for example, 1 to 50 mol%, preferably 2 to 40 mol%, more preferably 3 to 30 mol% (particularly 5 to 5 mol%) with respect to all monomers. 20 mol%). The composite ratio (mass ratio) of the component forming the homopolymer and the component forming the modified polymer can be selected according to the structure of the fiber. For example, the homopolymer component (A) / modified polymer component (B) = 90/10 to 10/90, preferably 70/30 to 30/70, more preferably about 60/40 to 40/60.

  In the present invention, a combination of a plurality of resins is a combination of an aromatic polyester resin, in particular, a polyalkylene arylate resin (a) and a modified polyalkylene arylate resin (b) because of the excellent balance of various properties. It may be a combination.

The polyalkylene arylate resin (a) is an aromatic dicarboxylic acid (such as a symmetric aromatic dicarboxylic acid such as terephthalic acid or naphthalene-2,6-dicarboxylic acid) or a reactive derivative thereof (such as an acid chloride or a lower alkyl ester). And an alkanediol component (C _2-6 alkanediol such as ethylene glycol or butylene glycol) may be a homopolymer. Specifically, poly C _2-4 alkylene terephthalate resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) are used, and generally a general PET having an intrinsic viscosity of about 0.6 to 0.7. PET used for fibers is used.

On the other hand, in the modified polyalkylene arylate resin (b), the melting point or softening point of the polyalkylene arylate resin (a), which is an essential component, is a copolymer component that lowers the crystallinity, such as an asymmetric aromatic dicarboxylic acid. Further, a dicarboxylic acid component such as alicyclic dicarboxylic acid or aliphatic dicarboxylic acid, an alkanediol component having a chain length longer than the alkanediol of the polyalkylene arylate resin (a) and / or an ether bond-containing diol component can be used. These copolymerization components can be used alone or in combination of two or more. Among these components, as dicarboxylic acid components, asymmetric aromatic carboxylic acids (isophthalic acid, phthalic acid, 5-sodium sulfoisophthalic acid, etc.), aliphatic dicarboxylic acids (C _6-12 aliphatic dicarboxylic acids such as adipic acid, etc.) ) such as is commonly, as the diol component, alkane diol (1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, etc. C _3-6 alkanediol such as neopentyl glycol), (poly) Oxyalkylene glycol (polyoxy C _2-4 alkylene glycol such as diethylene glycol, triethylene glycol, polyethylene glycol, polytetramethylene glycol, etc.) is widely used. Among these, asymmetric aromatic dicarboxylic acids such as isophthalic acid, polyoxy C _2-4 alkylene glycol such as diethylene glycol, and the like are preferable. Further, the modified polyalkylene arylate resin (b) may be an elastomer having C _2-4 alkylene arylate (ethylene terephthalate, butylene terephthalate, etc.) as a hard segment and (poly) oxyalkylene glycol as a soft segment. .

  In the modified polyalkylene arylate resin (b), as the dicarboxylic acid component, the ratio of the dicarboxylic acid component (for example, isophthalic acid) for lowering the melting point or the softening point is, for example, relative to the total amount of the dicarboxylic acid component, It is 1-50 mol%, Preferably it is 5-50 mol%, More preferably, it is about 15-40 mol%. The ratio of the diol component (for example, diethylene glycol) for reducing the melting point or the softening point as the diol component is, for example, 30 mol% or less, preferably 10 mol% or less (for example, 0 mol%) with respect to the total amount of the diol component. .About 1 to 10 mol%). When the proportion of the copolymer component is too low, sufficient crimp is not exhibited, and the uniformity of the crimp is lowered.

  Modified polyalkylene arylate resin (b) is used in combination with polyvalent carboxylic acid components such as trimellitic acid and pyromellitic acid, and polyol components such as glycerin, trimethylolpropane, trimethylolethane, and pentaerythritol as necessary. And may be branched.

  The bulky fiber structure of the present invention needs to contain 25% by mass or more of the heat-adhesive fiber, preferably 25 to 95% by mass, more preferably from the viewpoint of form stability. May contain about 30-90 mass%.

  The ratio (mass ratio) of the heat-bondable fiber and the crimped fiber is, for example, from the range of the former / the latter = 99/1 to 25/75 (for example, 95/5 to 25/75) depending on the application. In applications where cushioning and flexibility are important, the proportion of crimped fibers may be increased, and in applications where rigidity and hardness are important, the proportion of thermally adhesive fibers may be increased. The ratio of both fibers is, for example, the former / the latter = 90 / 10-30 / 70, preferably 85 / 15-35 / 65, more preferably 80 / 20-40 / 60 (especially 70 / 30-50 / 50). Degree. If the ratio of both is in this range, the balance between the fiber entanglement by the crimped crimp of the crimped fiber and the fusion of the heat-adhesive fiber is good, and the cushioning property and flexibility are excellent, and the shape stability is improved. it can.

  In addition to these fibers, the bulky fiber structure of the present invention may contain other fibers as long as the properties of the fibers are not impaired. Other fibers include, for example, fibers composed of a thermoplastic resin exemplified in the section of thermal adhesive fibers, fibers composed of a thermoplastic resin exemplified in the section of crimped conjugate fibers, and cellulose. Fiber (for example, natural fiber (cotton, wool, silk, hemp, etc.), semi-synthetic fiber (acetate fiber, such as triacetate fiber), regenerated fiber (rayon, polynosic, cupra, lyocell (eg, registered trademark name: “Tencel”)) Etc.)], etc.], inorganic fibers (for example, carbon fiber, glass fiber, metal fiber, etc.) can be used. The average fineness and average fiber length of the other fibers are the same as those of the crimped fibers. These other fibers can be used alone or in combination of two or more.

  Of these other fibers, regenerated fibers such as rayon, semi-synthetic fibers such as acetate, polyolefin fibers such as polypropylene and polyethylene, polyester fibers, and polyamide fibers are preferable. In particular, from the viewpoint of blendability, it may be the same type of fiber as a heat-adhesive fiber or a crimped fiber. For example, when the crimped fiber is a polyester fiber, the other fiber is also a polyester fiber. Also good.

  The proportion of other fibers is, for example, 20% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less (for example, about 0.1 to 5% by mass) with respect to the entire fiber structure. .

  The bulky fiber structure of the present invention further comprises conventional additives such as stabilizers (heat stabilizers such as hindered phenols and copper compounds, ultraviolet absorbers, light stabilizers, antioxidants, etc.), fillers , Fine particles, lubricants, colorants (dyeing pigments, etc.), dispersants, thickeners, wetting agents, antistatic agents, flame retardants, plasticizers, lubricants, crystallization rate retarders, matting agents, antibacterial agents, insecticides It may contain an acaricide, a fungicide, a deodorant, a heat storage agent, a fragrance, a fluorescent brightening agent, and the like. These additives can be used alone or in combination of two or more. These additives may be carried on the surface of the fiber or may be contained in the fiber.

(Characteristics of bulky fiber structure)
The bulky fiber structure of the present invention has a non-woven fiber structure obtained from a web composed of the above fibers, and its external shape can be selected according to the application, but is usually a sheet or plate. . The planar shape is not particularly limited, and may be, for example, a circular or elliptical shape, a polygonal shape, or a square shape such as a square or a rectangle.

  Furthermore, in the bulky fiber structure of the present invention, in order to obtain a non-woven fiber structure having a good balance between air permeability and cushioning properties, in the internal shape of the fiber structure, the fibers are bonded by fusing the heat-adhesive fibers. The adhesion state is appropriately adjusted, and adjacent or intersecting fibers need to be entangled with each other in the crimped coil portion by crimping the crimped fibers.

  Specifically, the bulky fiber structure including the latent crimpable conjugate fiber has an intersection at which the heat-adhesive fiber intersects with the crimped fiber or other heat-adhesive fibers (that is, the intersection between the heat-adhesive fibers, thermal adhesiveness). It is preferable that the fibers are fused at the intersection of the fibers and the crimped fibers. In the present invention, in the bulky fiber structure, the fibers constituting the non-woven fiber structure are bonded at the contact points of each fiber by heat-adhesive fibers, but the shape of the fiber structure is maintained with as few contacts as possible. In order to achieve this, it is preferable that the adhesion points are distributed substantially uniformly from the vicinity of the surface of the structure to the inside thereof. For example, when the structure is plate-shaped, it is uniformly distributed from the surface of the structure to the inside (center) and back, along the surface direction and thickness direction (especially in the thickness direction that is difficult to make uniform). It is preferable. When the adhesion points are concentrated on the surface or inside, the cushioning property is lowered, and the form stability in a portion having few adhesion points is lowered. For example, if the treatment is performed for a long time at a high temperature in order to achieve sufficient adhesion by a method using a heater or the like, the portion close to the heat source adheres excessively and cushioning properties (particularly flexibility with respect to initial stress) are reduced.

  On the other hand, the bulky fiber structure of the present invention is distributed almost uniformly from the vicinity of the surface of the structure to the inside, and efficiently fixes the fibers, so the number of fusion points by the heat-adhesive fibers is small. In spite of the fact that no elastomer component is used, the form stability can be exhibited, and both cushioning and sag resistance can be achieved. Furthermore, since the fibers are fused by the heat-bonding fibers, the fibers can be prevented from falling off. For example, even if the fiber structure is cut into a desired size and used, the fibers are removed from the cut surface. Is suppressed, and the structure is not easily destroyed.

  Specifically, in the bulky fiber structure of the present invention, the fiber constituting the nonwoven fiber structure is 30% or less (for example, 1 to 30%), preferably 1 by the fusion of the heat-adhesive fibers. 5 to 25%, more preferably about 2 to 20% (particularly 2 to 10%), and the fiber adhesion rate can be appropriately selected depending on the application. Although the fiber adhesion rate in this invention can be measured by the method as described in the Example mentioned later, the ratio of the cross section number of the fiber which adhered 2 or more with respect to the cross section number of all the fibers in a non-woven fiber cross section is shown. Therefore, a low fiber adhesion rate means that the proportion of fusion of a plurality of fibers is small. In the present invention, since the adhesion rate is low as described above, a good cushioning property can be exhibited in the fiber structure in combination with a coiled crimp of the crimped fiber described later.

  Regarding the uniformity of fusion, for example, when the structure is a sheet-like or plate-like body, in the cross section in the thickness direction of the structure, the fiber adhesion rate in each region divided in three in the thickness direction is within the above range. It is preferable that it exists in. Furthermore, the ratio of the minimum value to the maximum value of the fiber adhesion rate in each region (minimum value / maximum value) (the ratio of the minimum region to the region with the maximum fiber adhesion rate) is, for example, 50% or more (for example, 50 to 100%), preferably 55 to 99% (eg 60 to 99%), more preferably 60 to 98% (eg 70 to 98%), especially 70 to 97% (eg 75 to 97%). is there. In the present invention, since the fiber adhesion rate has such uniformity in the thickness direction, the form can be maintained even at a few fusion points, the cushioning property and the air permeability can be improved, and the flexibility and the form stability can be maintained. It can be compatible with sex.

  In the specification of the present application, the “region divided into three in the thickness direction” means each region divided into three equal parts by slicing in a direction orthogonal to the thickness direction of the plate-like structure.

  The fiber adhesion rate, which indicates the degree of fusion, can be easily calculated based on the number of bonded fiber cross sections in a predetermined region by taking a photograph of an enlarged cross section of the fiber structure using a scanning electron microscope (SEM). Can be measured. However, when the fibers are fused in a bundle shape, such as when the proportion of heat-bonding fibers is large, each fiber is fused in a bundle shape or at an intersection, so that it can be observed as a single fiber. It can be difficult. In this case, for example, the fiber adhesion rate can be measured by releasing the adhesion of the adhesion portion by means such as melting or washing and comparing with the cut surface before the release.

  As described above, in the fiber structure of the present invention, not only the fusion by the heat-adhesive fibers is uniformly dispersed and point-bonded, but also the point adhesion of these points is short (for example, several tens to The network structure is stretched densely at several hundred μm). With such a structure, the fiber structure of the present invention has a high followability to strain due to the flexibility of the fiber structure even when an external force is applied, and each fusion point of finely dispersed fibers. Therefore, it can be estimated that high morphological stability is exhibited. On the other hand, conventional porous molded bodies, foams, and the like are constituted by wall-like interfaces around the pores and have low air permeability.

  In particular, in the bulky fiber structure of the present invention, in order to obtain a non-woven fiber structure having a good balance between air permeability and cushioning properties, the inner shape of the fiber structure is obtained by fusing the heat-adhesive fibers. While the adhesion state is moderately adjusted, a plurality of adjacent or intersecting fibers (crimped fibers and thermally adhesive fibers, crimped fibers, or thermally bonded fibers) are entangled with each other and restrained or latched, The crimped coil portion of the crimped fiber has a structure that is entangled so as to surround a plurality of these intertwined fibers.

  In the bulky fiber structure of the present invention, the crimped fibers are preferably present uniformly in the thickness direction. Specifically, for example, in the cross section in the thickness direction, the number of fibers forming an arc of approximately 2/3 rounds or more in the central portion (inner layer) in each region divided in three in the thickness direction. For example, 3-60 pieces / 5 mm (length in the surface direction) × 1 mm (thickness), preferably 5-50 pieces / 5 mm (length in the surface direction) × 1 mm (thickness), more preferably 10 40 pieces / 5 mm (length in the surface direction) × 1 mm (thickness) (particularly 20 to 30 pieces / 5 mm (length in the surface direction) × 1 mm (thickness)). In the present invention, most of the crimped fibers and the inside of the structure (from the vicinity of the surface of the structure to the center) have a uniform number of crimps, so that even if it does not contain rubber or elastomer, it is highly flexible. And has a practical strength even if it does not contain an adhesive.

  Furthermore, the uniformity of crimps inside the fiber structure can be evaluated, for example, by the uniformity of fiber curvature in the thickness direction. The fiber curvature is a ratio (L2 / L1) of the fiber length (L2) to the distance (L1) between both ends of the fiber (crimped fiber), and the fiber curvature (particularly in the central region in the thickness direction). The fiber curvature ratio is, for example, 1.1 or more (for example, 1.1 to 5), preferably 1.15 to 4 (for example, 1.2 to 3.5), and more preferably 1.25 to 3 ( In particular, it is about 1.3 to 2.5). In the present invention, as will be described later, in order to measure the fiber curvature based on the electron micrograph of the cross section of the fiber structure, the fiber length (L2) is a straight line obtained by stretching the three-dimensionally crimped fiber. It does not mean the fiber length (actual length) made into a shape, but the fiber length (fiber length on the photograph) obtained by stretching the two-dimensionally crimped fibers shown in the photograph into a straight line. That is, the fiber length (fiber length on the photograph) in the present invention is measured shorter than the actual fiber length.

  Furthermore, in the present invention, substantially uniform crimps exist inside the structure (that is, crimped fibers having a uniform crimp size and number of crimps are uniformly distributed in the thickness direction). ), The fiber curvature is uniform, and good cushioning properties and heat insulation properties are ensured. In the present invention, the uniformity of the fiber bending rate can be evaluated by, for example, comparing the fiber bending rate in each layer that is divided into three equal parts in the thickness direction in the cross section in the thickness direction of the structure. That is, in the cross section in the thickness direction, the fiber curvature rate in each region divided in three in the thickness direction is in the above range, and the ratio of the minimum value to the maximum value of the fiber curvature rate in each region (the fiber curvature rate is the maximum). The ratio of the minimum area to the area of (ii) is, for example, 75% or more (for example, 75 to 100%), preferably 80 to 99.9%, more preferably 90 to 99.5% (particularly 95 to 99%). Degree.

  As a specific method for measuring the fiber curvature and its uniformity, a method of taking a cross-section of the fiber structure with an electron micrograph and measuring the fiber curvature for a region selected from each region divided in three in the thickness direction Is used. The area to be measured is measured in an area of 2 mm or more in the length direction for each of the surface layer (surface area), inner layer (center area), and back layer (back area) divided into three. Further, the thickness direction of each measurement region is set so that each measurement region has the same thickness width in the vicinity of the center of each layer. Furthermore, each measurement region includes 100 or more (preferably about 300 or more, more preferably about 500 to 1000) fiber pieces that are parallel in the thickness direction and capable of measuring the fiber curvature in each measurement region. Set as follows. After setting each of these measurement regions, after measuring the fiber curvature rate of all the fibers in the region, calculating the average value for each measurement region, the region showing the maximum average value and the minimum average value The uniformity of the fiber curvature is calculated by comparison with the region shown.

  In the fiber structure including such heat-adhesive fibers and crimped fibers, the orientation of each fiber is not particularly limited. For example, in the case of a sheet shape or a plate shape, fibers constituting the fiber structure (particularly heat bonding) The alignment state of the fibers may be adjusted appropriately. In other words, the heat-adhesive fibers (or the heat-adhesive fibers and other fibers) constituting the fiber structure may be arranged so as to intersect each other while being arranged substantially parallel to the sheet surface. In the present specification, “orientated substantially parallel to the surface direction” means that a large number of fibers penetrate the nonwoven fabric in the thickness direction locally, such as a general needle punch nonwoven fabric. This means a state in which the shape of the nonwoven fabric is maintained by constraining the fibers to each other and the portion that contributes to achieve a large strength is not repeatedly present. Therefore, from the viewpoint of arranging the fibers in parallel, it is preferable that the degree of entanglement of the fibers by the needle punch is reduced or not entangled.

  Furthermore, in such a plate-like structure, when the heat-adhesive fibers are arranged parallel to the sheet surface, adjacent or intersecting heat-adhesive fibers are entangled with each other. Even in the thickness direction (or oblique direction), the fibers are slightly entangled. In particular, in the present invention, the crimped coil portion of the crimped fiber is entangled so as to surround a plurality of heat-bonded fibers arranged in layers in the thickness direction, and the fibers are appropriately restrained by fusing. Yes. Furthermore, since the entangled fibers are fused by the heat-bonding fibers, they exhibit cushioning properties.

  Furthermore, the coiled crimped fiber is easily deformed with respect to the force applied to the length direction (axial core) and is difficult to return to the original shape, but for the force from the coil side surface direction, It is difficult to deform, and even if it is deformed, it easily returns to its original shape. Therefore, the bulky fiber structure of the present invention can achieve both form maintenance and cushioning properties, although the fusion bonding point of the heat-bonding fibers is small.

  The bulky fiber structure of the present invention usually has anisotropy between the flow direction (MD direction) and the width direction (CD direction) in the production process, as well as the anisotropy between the surface direction and the thickness direction. doing. That is, in the bulky fiber structure of the present invention, in the process of production, not only the heat-adhesive fibers are substantially parallel to the surface direction, but also the heat-adhesive fibers oriented substantially parallel to the surface direction are However, it tends to be substantially parallel. As a result, when a rectangular fiber structure is manufactured, anisotropy appears between the flow direction and the width direction in the manufacture of the fiber structure.

  Since the bulky fiber structure of the present invention has a non-woven fiber structure, it has voids formed between the fibers. Unlike the resin foam such as sponge, these voids are not independent voids but are continuous, and thus have air permeability. In particular, the bulky fiber structure of the present invention realizes high lightness and air permeability by entanglement by a relatively large crimped coil portion of crimped fibers.

Specifically, the air permeability of the bulky fiber structure of the present invention is 1 cm ³ / (cm ² · sec) or more (for example, 1 to 500 cm ³ / (cm ² · sec)) as measured by the Frazier method. For example, 10 to 450 cm ³ / (cm ² · sec), preferably 50 to 400 cm ³ / (cm ² · sec), more preferably 80 to 300 cm ³ / (cm ² · sec) (particularly 100 ˜250 cm ³ / (cm ² · sec))), usually about 100 to 300 cm ³ / (cm ² · sec). If the air permeability is too small, it is necessary to apply pressure from the outside in order to allow air to pass through the fiber structure, making it difficult for natural air to enter and exit. On the other hand, if the air permeability is too high, the fiber voids in the fiber structure become too large, and the cushioning property is lowered. In this invention, since it has such a high air permeability, even if it uses for the use which contacts a human body, it can utilize comfortably without being steamed.

The apparent density of the bulky fiber structure of the present invention can be selected, for example, from a range of about 0.01 to 0.1 g / cm ³ , for example, 0.012 to 0.08 g / cm ³ , preferably Is about 0.013 to 0.05 g / cm ³ (particularly 0.015 to 0.03 g / cm ³ ). If the apparent density is too low, the air permeability is improved, but the form stability is lowered. On the other hand, if the apparent density is too high, the form stability can be secured, but the air permeability and cushioning ability are lowered. In the present invention, the combination of fusion by heat-bonding fibers and entanglement by crimped coil portions of crimped fibers provides cushioning properties while maintaining the form of the fiber structure despite its low density. It is possible to do.

The basis weight (weight per unit area after heating) of the bulky fiber structure of the present invention can be selected from the range of, for example, about 50 to 10,000 g / m ² , preferably 150 to 5000 g / m ² , more preferably 200, depending on the application. It is about -3000 g / m < ² > (especially 300-2000 g / m < ² >). Note that when used as a rigid or hard highly cushioning material, for example, 500~10000g / m ^2, preferably 1000~8000g / m ^2, more preferably a 1200~5000g / m ²⁾ approximately Also good. If the basis weight is too small, it is difficult to ensure cushioning and form stability, and if the basis weight is too large, it is too thick to allow high-temperature steam to sufficiently enter the web during wet heat processing and melt in the thickness direction. It becomes difficult to obtain a structure with uniform wearing.

  The bulky fiber structure of the present invention has excellent cushioning properties, in particular, low initial stress and flexible touch. About such cushioning properties, in the hysteresis loop of the behavior (50% compression recovery behavior) that has been compressed and recovered to 50% according to JIS K6400-2, the initial 50% compression behavior at the time of 25% compression It can be expressed by the ratio (Y / X) of the stress [compression stress (X)] and the stress [recovery stress (Y)] at 25% compression in the return (recovery) behavior after 50% compression. In the fiber structure of the present invention, for example, the ratio in at least one direction (such as the thickness direction) may be 30% or more, for example, 35% or more (for example, about 35 to 90%), preferably 40%. Above (for example, about 40 to 80%), more preferably about 45 to 60%. This ratio (Y / X) can be selected from such a range according to the application. The higher this ratio, the better the cushioning properties.In this invention, this ratio is high, so even though it is a soft touch, even if the repulsive force is slowly increased according to the load, the load can be released. The form is restored.

  The bulky fiber structure of the present invention has high flexibility, and the compressive stress required for compression by 25% is, for example, about 0.1 to 1 N / 30 mmφ (particularly 0.2 to 0.5 N / 30 mmφ). On the other hand, the compressive stress required for 50% compression may be, for example, about 0.5 to 5 N / 30 mmφ (particularly 0.8 to 3 N / 30 mmφ). Furthermore, when used for applications with high rigidity and rigidity, the compressive stress required for 25% compression is, for example, about 1 to 20 N / 30 mmφ (especially 5 to 20 N / 30 mmφ), whereas 50 The compressive stress required for% compression may be, for example, about 5 to 50/30 mmφ (particularly 10 to 40/30 mmφ).

  The bulky fiber structure of the present invention has high flexibility and a high compressibility. Specifically, the compression rate may be, for example, 50% or more, for example, about 60 to 99%, preferably 65 to 98%, and more preferably about 70 to 95% (particularly 75 to 90%). . In the present invention, the nonwoven fabric structure is excellent in cushioning properties but has high flexibility, so that the structure can be greatly compressed even under a low load.

  The bulky fiber structure of the present invention is not only flexible but also excellent in compression durability. For example, even when it is repeatedly used as a cushioning material, there is little decrease in cushioning performance. The fiber structure of the present invention has a return rate after repeated compression of 70 in a test based on the repeated compression residual strain test B method (constant displacement method) of JIS K6400-4, which is an index representing such compression durability. %, Preferably 75% or more (for example, 75 to 99%), more preferably 80% or more (for example, 80 to 98%), particularly 85 to 97% (for example, 90 to 96%). Degree. Therefore, the bulky fiber structure of the present invention has little sag even when used as a cushion material for a long period of time.

  When the fiber structure of the present invention is plate-shaped or sheet-shaped, the thickness is not particularly limited, but can be selected from a range of about 1 to 500 mm, for example, 5 to 300 mm, preferably 10 to 150 mm, and more preferably. It is about 15-100 mm (especially 20-50 mm). If the thickness is too thin, it will be difficult to develop cushioning properties. In addition, you may laminate | stack and use a sheet-like fiber structure. Furthermore, although the fiber structure of the present invention has a non-woven fiber structure, there are few variations in thickness (thickness unevenness) even in a plate shape or a sheet shape, and the thickness is substantially uniform. It can be used effectively as a cushioning material.

  When a wet heat adhesive fiber such as ethylene-vinyl alcohol fiber is used as the bulky fiber structure of the present invention, in particular, the heat adhesive fiber, water absorption (and from the capillary effect of the fiber and the affinity of the wet heat adhesive resin) Water retention) and moisture permeability are high.

  On the other hand, a fiber structure using a hydrophobic thermoplastic fiber such as a polyester fiber as the heat-adhesive fiber has high water repellency. In particular, in the present invention, the fiber structure is water or water vapor in the manufacturing process described later. As a result, the hydrophilic substance attached to the fiber is washed away, and the inherent hydrophobicity of the resin is effectively expressed on the surface of the fiber. Specifically, this water repellency is preferably 3 or more (preferably 3 to 5 points, more preferably 4 to 5 points) in the JIS L1092 spray test. Furthermore, the fiber structure of the present invention is also effective for use in contact with the human body because the fiber oil agent adhering to the fibers is washed away and the skin irritation is reduced due to the cleaning effect of water and water vapor.

  Although the bulky fiber structure of the present invention has a high cushioning property and flexibility, it has an appropriate surface hardness, and has an FO type durometer hardness test (“vulcanization of JIS K6253” The hardness according to the test based on “the hardness test method of rubber and thermoplastic rubber” is, for example, 5 or more (for example, 5 to 100), preferably 8 or more (for example, 8 to 80), and more preferably 10 or more ( For example, it is about 10 to 70). In particular, in applications where flexibility is required, it may be about 10 to 20, for example. In addition, when using for the use as which rigidity is requested | required, hardness may be 20-100, for example, Preferably about 30-80 may be sufficient.

  Since the bulky fiber structure of the present invention has a non-woven fiber structure, the heat insulation is also high, and the thermal conductivity is as low as 0.1 W / m · K or less, for example, 0.01 to 0.1 W / m · K, preferably 0.02 to 0.08 W / m · K, more preferably about 0.03 to 0.07 W / m · K.

[Method for producing bulky fiber structure]
The method for producing a bulky fiber structure according to the present invention includes a step of forming a fiber including the thermal adhesive fiber and the crimped fiber (or a latent crimpable fiber of the crimped fiber), and the generated fiber web. Heating and humidifying with high-temperature steam and fusing.

  In the method for producing a bulky fiber structure of the present invention, first, a fiber containing the thermal adhesive fiber and the crimped fiber (or the latent crimpable fiber of the crimped fiber) is formed into a web. As a method for forming the web, a conventional method, for example, a direct method such as a spun bond method or a melt blow method, a card method using melt blow fibers or staple fibers, a dry method such as an air array method, or the like can be used. Among these methods, a card method using melt blown fibers or staple fibers, particularly a card method using staple fibers is widely used. Examples of the web obtained using staple fibers include a random web, a semi-random web, a parallel web, and a cross-wrap web.

  Next, the obtained fiber web is sent to the next process by a belt conveyor, heated and humidified with high-temperature steam, and the fibers are bonded three-dimensionally by fusing the heat-adhesive fibers. In addition, when using latent crimpable fibers, crimping of the fibers is caused by heating, and the fiber entanglement also proceeds at the same time. In this case, the mixing ratio of the heat-adhesive fibers can be kept low. A softer cushioning material can be obtained. In the present invention, by using a method of treating with high-temperature steam as a heating method, uniform fusion can be expressed from the surface to the inside of the fiber structure.

  In addition, when using crimped fibers that have already been crimped in advance by heat treatment or the like, in order to allow the crimped fibers to be uniformly present in the thickness direction of the structure, the heat-adhesive fibers and the crimped fibers are sufficiently combined. It becomes important to blend. That is, since the crimped fiber that has been crimped in advance has high uniformity such as the radius of curvature and the number of crimps, a nonwoven fiber structure having uniform crimp can be produced by a simple method such as blending. On the other hand, when the latent crimpable fiber is used, crimp is developed by heat treatment with high-temperature steam. In the present invention, even when a latent crimpable fiber is used, it can be uniformly heated in the thickness direction of the web by high-temperature steam, so that uniform crimp can be expressed from the surface to the inside of the fiber web. That is, in the present invention, a non-woven fiber structure having a uniform crimp in the thickness direction can be obtained as compared with a dry heat treatment such as hot air even if latent crimpable fibers are used. It is preferable to use crimped fibers that have been crimped in advance from the viewpoint that a nonwoven fiber structure having crimps can be easily produced.

  Specifically, the obtained fiber web is sent to the next process by a belt conveyor, and then exposed to a superheated or high-temperature steam (high-pressure steam) stream to obtain a fiber structure having a nonwoven fiber structure. That is, when the fiber web transported by the belt conveyor passes through the high-speed high-temperature steam flow ejected from the nozzle of the steam spraying device, the fibers are bonded to each other by fusing the heat-adhesive fibers with the sprayed high-temperature steam. Heat-adhesive fibers or other fibers such as heat-adhesive fibers and crimped fibers) are three-dimensionally bonded. In particular, the non-woven fiber structure has a structure having an appropriate gap when the heat-bonding fiber surrounded by the crimped coil portion of the crimped fiber is bonded to the coil portion. In particular, since the fiber web in the present invention has air permeability, high-temperature water vapor can penetrate into the inside, and a fiber structure having a substantially uniform fusion state can be obtained.

  The belt conveyor to be used is not particularly limited as long as it can be subjected to high temperature steam treatment without disturbing the form of the fiber web used for processing, and an endless conveyor is preferably used. In addition, a general independent belt conveyor may be used, and another belt conveyor may be combined as necessary, and the web may be transported with the web sandwiched between both belts. By conveying in this way, when processing a fiber web, it can suppress that the form of the fiber web conveyed by external force, such as the water used for a process, high temperature steam, and a conveyor's vibration, deform | transforms. It is also possible to control the density and thickness of the treated non-woven fibers by adjusting the distance between the belts.

  In order to supply water vapor to the fiber web, a conventional water vapor jet apparatus is used. As this steam spraying device, a device capable of spraying steam substantially uniformly over the entire width of the web at a desired pressure and amount is preferable. When two belt conveyors are combined, water vapor is supplied to the web through a water-permeable conveyor belt or a conveyor net placed on the conveyor. A suction box may be attached to the other conveyor. Excess water vapor that has passed through the fiber web can be sucked and discharged by the suction box. Further, in order to perform steam treatment on both sides of the front and back of the fiber web at a time, in a conveyor opposite to the conveyor on which the steam spraying device is mounted, more than the portion on which the steam spraying device is mounted. You may install another water vapor | steam injection apparatus in the conveyor of a downstream part. If there is no downstream steam injection device and suction box, and if you want to steam-treat the front and back of the fiber web, you can reverse the front and back of the fiber web that has been treated once and pass it through the processing device again. Good.

  The endless belt used for the conveyor is not particularly limited as long as it does not hinder the conveyance of the fiber web or the high-temperature steam treatment. However, when high-temperature steam treatment is performed, the surface shape of the belt may be transferred to the surface of the fiber web depending on the conditions. In particular, in order to obtain a fiber structure having a flat surface, a net with a fine mesh may be used. The upper limit is about 90 mesh, and a net that is roughly coarser than 90 mesh (for example, a net of about 10 to 50 mesh) is preferable. A finer mesh net than this has low air permeability and makes it difficult for water vapor to pass through. The mesh belt is made of metal, heat-treated polyester resin, polyphenylene sulfide resin, polyarylate resin (fully aromatic polyester resin), aromatic polyamide resin, etc. The heat resistant resin is preferable.

  Since the high-temperature steam sprayed from the steam spraying device is an air stream, unlike the water entanglement process or the needle punch process, the fiber in the fiber web that is the object to be processed enters the fiber web without moving significantly. To do. Due to the invasion action and wet heat action of the water vapor flow into the fiber web, the water vapor flow effectively covers the surface of each fiber existing in the fiber web in a wet heat state, and uniform heat bonding (and heat crimping) is possible. It is thought that it becomes. In addition, since this treatment is performed in a very short time under a high-speed air stream, the heat conduction to the surface of each fiber is sufficient, but the treatment is completed before the heat conduction to the inside of the fiber is sufficiently achieved. Therefore, the entire fiber web to be processed is not crushed by the pressure or heat of high-temperature steam, and deformation that damages its thickness is unlikely to occur. As a result, the thermal bonding is completed so that the degree of adhesion in the surface and the thickness direction is substantially uniform without causing a large deformation in the fiber web. Furthermore, since heat can be sufficiently conducted to the inside of the fiber as compared with the dry heat treatment, the degree of fusion in the surface and the thickness direction becomes substantially uniform.

Furthermore, when obtaining a fiber structure having a relatively high form stability, when the high-temperature steam is supplied to the web for processing, the target web is processed between the conveyor belt or the rollers and the desired apparent density. You may expose to high temperature water vapor | steam in the state compressed (for example, about 0.03-0.1 g / cm < ³ >). As a compression method, for example, by securing an appropriate clearance between rollers or between conveyors, it is possible to adjust to a target thickness or density. In the case of a conveyor, it is difficult to compress the fiber web all at once, so it is preferable to set the belt tension as high as possible and gradually narrow the clearance from the upstream of the steam treatment point. At this time, if it is desired to make the fiber structure more stable, the back side of the endless belt on the opposite side of the nozzle across the web is made of a stainless steel plate or the like so that water vapor cannot pass through the structure. Since the water vapor that has passed through the fiber web is reflected here, it is more firmly bonded by the heat retaining effect of the water vapor. Conversely, when light adhesion is required, a suction box may be provided to discharge excess water vapor to the outside.

  The nozzle for injecting the high-temperature steam may be a plate or a die in which predetermined orifices are continuously arranged in the width direction, and may be arranged so that the orifices are arranged in the width direction of the fiber web to be supplied. There may be one or more orifice rows, and a plurality of rows may be arranged in parallel. A plurality of nozzle dies having a single orifice array may be installed in parallel.

  When using a type of nozzle having an orifice in the plate, the thickness of the plate may be about 0.5 to 1 mm. The orifice diameter and pitch are not particularly limited as long as the target fiber fixation is possible, but the orifice diameter is usually 0.05 to 2 mm, preferably 0.1 to 1 mm, more preferably. It is about 0.2 to 0.5 mm. The pitch of the orifices is usually about 0.5 to 3 mm, preferably about 1 to 2.5 mm, and more preferably about 1 to 1.5 mm. If the orifice diameter is too small, the processing accuracy of the nozzle becomes low and the processing becomes difficult, and the operational problem that clogging is likely to occur easily occurs. On the other hand, if it is too large, it will be difficult to obtain a sufficient water vapor injection force. On the other hand, if the pitch is too small, the nozzle holes become too dense and the strength of the nozzle itself is reduced. On the other hand, if the pitch is too large, there are cases where high-temperature water vapor does not sufficiently hit the fiber web, making it difficult to ensure web strength.

  The high-temperature steam used is not particularly limited as long as the target fiber can be fixed, and may be set depending on the material and form of the fiber used. The steam pressure (steam pressure) is, for example, 0.01 to The pressure is about 1 MPa, preferably about 0.03 to 0.5 MPa, and more preferably about 0.07 to 0.3 MPa. If the water vapor pressure is too high or too strong, the fibers that make up the web may move more than necessary, causing turbulence, or the fibers may melt too much to partially retain the fiber shape. There is. If the pressure is too weak, the amount of heat required for fiber fusion cannot be applied to the web being processed, or water vapor cannot penetrate the web, causing fiber fusion spots (non-uniformity) in the thickness direction. ) May occur. In addition, it may be difficult to control the uniform ejection of water vapor from the nozzle.

  The temperature of the high-temperature steam is, for example, about 70 to 150 ° C., preferably 80 to 130 ° C., more preferably 90 to 120 ° C. (particularly 100 to 120 ° C.). The processing speed of the high temperature steam is, for example, 200 m / min or less, preferably 0.1 to 100 m / min, and more preferably about 1 to 50 m / min.

  If necessary, a plurality of plate-like fiber structures may be stacked to form a stacked body, or may be stacked with other materials to form a stacked body. Further, it may be processed into a desired form (various shapes such as a cylindrical shape, a quadrangular prism shape, a spherical shape, and an ellipsoidal shape) by molding.

  After the fibers of the fiber web are partially thermally bonded in this way, moisture may remain in the resulting nonwoven fiber structure, and the fiber structure may be dried as necessary. For drying, it is necessary that the fiber on the surface of the structure in contact with the heating element for drying does not melt and lose its fiber form due to the heat of drying, and the conventional method is used as long as the fiber form can be maintained. it can. For example, a large dryer such as a cylinder dryer or tenter used for drying nonwoven fabrics may be used, but the remaining moisture is very small and can be dried by a relatively light drying means. Therefore, a non-contact method such as far-infrared irradiation, microwave irradiation, electron beam irradiation, or a method of blowing or passing hot air is preferable.

  Further, as described above, the bulky fiber structure of the present invention can be obtained by adhering heat-adhesive fibers with high-temperature steam, but partially (such as adhesion between the obtained fiber structures) or other conventional uses. For example, it may be bonded by a processing method such as partial hot-pressure fusion (such as hot embossing) or mechanical compression (such as needle punch).

  The bulky fiber structure obtained by such a method is usually in the form of a plate or a sheet and may be used as it is. However, a square sheet is obtained by cutting or the like according to the shape of the intended use. And processed into rectangular sheets. Further, it may be processed into a desired form (various shapes such as a columnar shape, a quadrangular prism shape, a spherical shape, and an ellipsoid shape) by molding. Furthermore, the obtained plate-shaped or sheet-shaped molded body may be processed into a desired shape (curved processing or the like) by conventional thermoforming or the like. Examples of thermoforming methods include compression molding, pressure forming (extrusion pressure forming, hot plate pressure forming, vacuum pressure forming, etc.), free blow molding, vacuum forming, bending, matched mold forming, hot plate forming, hot press forming. Etc. are available.

  The bulky fiber structure of the present invention has high breathability and is excellent in cushioning properties and form stability (holding property), and therefore, cushioning materials in various fields such as industry, agriculture, daily life materials such as furniture ( Sofa, bed, etc.), bedding (futon, etc.), clothing, daily necessities (sheet cushion, rug, etc.), packaging materials, and cushioning materials for vehicles. In addition, cushioning materials such as brassiere cups, shoulder pads, shoe insoles (such as cushioning materials or protective materials) for touching or wearing the human body by utilizing its soft texture and low skin irritation. Material). In particular, by using excellent cushioning and compression durability, it is possible to provide a high degree of sitting comfort (cushion) with long-time movement, such as vehicles such as automobiles, motorcycles, bicycles, trains, airplanes, ships, etc. It is also useful as a cushioning material for a seat (such as a part where the buttocks contact or a backrest part where the back contacts) that requires high performance, durability, and breathability.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. Each physical property value in the examples was measured by the following method. In the examples, “%” is based on mass unless otherwise specified.

(1) Weight per unit (g / m ² )
Measured according to JIS L1913 “Testing method for general short fiber nonwoven fabric”.

(2) Thickness (mm), apparent density (g / cm ³ )
The thickness was measured according to JIS L1913 “Test method for general short fiber nonwoven fabric”, and the apparent density was calculated from this value and the basis weight value.

(3) Number of crimps Evaluation was made according to JIS L1015 “Testing method for chemical fiber staples” (8.12.1).

(4) Average curvature radius Using a scanning electron microscope (SEM), a photograph was taken of a cross section of the nonwoven fiber structure enlarged 25 times. Of the fibers shown in the photograph of the cross-section of the non-woven fibrous structure, the radius of the circle when a circle is drawn along the spiral of the fibers forming an arc of approximately 2/3 or more rounds ( The radius of the circle when the crimped fiber was observed from the coil axis direction) was determined, and this was taken as the radius of curvature. In addition, when the fiber has drawn the spiral in the ellipse shape, 1/2 of the sum of the major axis and the minor axis of the ellipse was used as the radius of curvature. However, in order to exclude the case where the crimped fiber does not exhibit sufficient coil crimping or the case where the spiral shape of the fiber is reflected as an ellipse, the major axis and minor axis of the ellipse Only the ellipses whose ratio is in the range of 0.8 to 1.2 were measured. In addition, the measurement was performed with respect to an SEM image taken for an arbitrary cross section, and was shown as an average value of n number = 100.

(5) Fiber curvature and uniformity thereof An electron micrograph (magnification x 25 times) in the cross section of the nonwoven fiber structure was taken, and in the projected portion of the taken fiber, in the thickness direction, the surface layer, the inner layer, The measurement area was set so as to be divided into three equal parts in the back layer, and in the vicinity of the center of each layer, the length direction was 2 mm or more and 500 or more measurable fiber pieces were included. For these regions, the end-to-end distance (shortest distance) between one end of the fiber and the other end was measured, and the fiber length of the fiber (fiber length on the photograph) was measured. That is, when the end of the fiber is exposed on the surface of the non-woven fiber structure, the end is used as it is as an end for measuring the distance between the ends, and the end is inside the non-woven fiber structure. When buried, the boundary part (end part on the photograph) buried inside the nonwoven fiber structure was used as an end part for measuring the distance between the end parts. At this time, among the photographed fibers, a fiber image that cannot be confirmed to be continuous over 100 μm or more was excluded from measurement. And fiber curvature was computed from ratio (L2 / L1) of the fiber length (L2) of the fiber with respect to the distance (L1) between edge parts. In addition, the measurement of fiber curvature calculated the average value for every surface layer, inner layer, and back layer divided into three equal to the thickness direction. Furthermore, the uniformity in the thickness direction of the fiber curvature was calculated from the ratio between the maximum value and the minimum value of each layer.

  In FIG. 1, the schematic diagram about the measuring method of the image | photographed fiber is shown. FIG. 1 (a) shows a fiber in which one end is exposed on the surface and the other end is buried inside the non-woven fiber structure. In the case of this fiber, the end-to-end distance L1 is the end of the fiber. It becomes the distance from the part to the boundary part buried in the nonwoven fiber structure. On the other hand, the fiber length L2 is a length obtained by two-dimensionally stretching the fiber of the portion where the fiber can be observed (the portion from the end of the fiber until it is buried in the non-woven fiber structure) on the photograph.

  FIG. 1 (b) shows a fiber in which both ends are buried in the nonwoven fiber structure, and in the case of this fiber, the distance L1 between the ends is the both ends of the portion exposed on the surface of the nonwoven fiber structure ( This is the distance between the two ends on the photo. On the other hand, the fiber length L2 is a length obtained by two-dimensionally stretching the portion of the fiber exposed on the surface of the nonwoven fiber structure on the photograph.

(6) Fiber adhesion rate Using a scanning electron microscope (SEM), a photograph was taken of the fiber structure cross section enlarged 25 times. The photograph of the cross section in the thickness direction of the captured fiber structure is divided into three equal parts in the thickness direction, and the fiber cut surfaces (fiber end faces) that can be found in each of the three divided areas (front surface, inside (center), back surface) The ratio of the number of cut surfaces where the fibers are bonded to each other was determined. Of the total number of fiber cross sections that can be found in each region, the ratio of the number of cross sections in a state where two or more fibers are bonded is expressed as a percentage based on the following formula. In addition, in the part which fibers contact, there exists a part which is simply contacting, without melt | fusion, and a part which has adhere | attached by melt | fusion. However, by cutting the fiber structure for microscopic photography, the fibers that are simply in contact with each other are separated from each other by the stress of each fiber on the cut surface of the fiber structure. Therefore, in the cross-sectional photograph, it can be determined that the contacting fibers are bonded to each other.

Fiber adhesion rate (%) = (number of cross sections of fibers bonded two or more) / (total number of cross sections of fibers) × 100
However, for each photograph, all the fibers with visible cross sections were counted, and when the number of fiber cross sections was 100 or less, a photograph to be observed was added so that the total fiber cross section number exceeded 100. In addition, the fiber adhesion rate was calculated | required about each area | region divided into three equally, and the uniformity in the thickness direction was computed from the ratio of the maximum value and the minimum value.

(7) 25% stress, 50% stress, 25% recovery / compression stress ratio, compression recovery rate According to JIS K6400-2 “7.3 Compression Deflection Measurement Method B”, a 40 mmφ circular pressure plate is applied at 100 mm / min. 25% from the force-deflection curve when moving at speed and pushing to 50% of the initial thickness of a 30 mmφ cylindrical sample and then immediately returning at the same speed (when the load is removed at the same speed) The values of the stress at the time of compression and the stress at the time of 50% compression are read, and the values are taken as 25% compression stress and 50% compression stress, respectively, and the stress at 25% compression (25% recovery stress) when returned to 25% Reading, the ratio with 25% compressive stress was calculated, and the ratio was 25% recovery / compressive stress.

(8) Compression rate (%)
Using a nonwoven fabric thickness measuring instrument, the thickness (A1) when a load of 0.5 g / m ² is applied to the fiber structure is measured. Next, the thickness (A2) when a load of 35 g / m ² was applied was measured and calculated according to the following formula.

    Compression rate (%) = 100 × (A1-A2) / A1.

(9) Compression durability (%)
JIS K6400-4 Part 4: Repeated compression residual strain test in compression residual strain and repeated compression residual strain Based on the B method (constant displacement method), the return rate (%) after repeated compression was measured.

(10) Surface hardness It measured according to the FO type durometer hardness test (the test based on the "hardness test method of vulcanized rubber and thermoplastic rubber" of JIS K6253).

(11) Thermal conductivity It measured by the unsteady hot wire method according to "JIS R2648, the test method of the heat conductivity by the hot wire method of a refractory heat insulation brick".

(12) Air permeability Measured by the fragile method according to JIS L1096.

Example 1
Core-sheath type composite staple fiber having a core component of polyethylene terephthalate and a sheath component of ethylene-vinyl alcohol copolymer (ethylene content 44 mol%, saponification degree 98.4 mol%) as wet heat adhesive fibers (Co., Ltd.) “Kuraray”, “Sophista”, fineness 3 dtex, fiber length 51 mm, core-sheath mass ratio = 50/50, number of crimps 21/25 mm, crimp ratio 13.5%) was prepared.

  On the other hand, polyethylene terephthalate-based highly crimped fibers (manufactured by Toray Industries, Inc., “T-12”, 5.6 dtex × 58 mm length, about 15 crimps / 25 mm, average radius of curvature 700 μm) are used as the coil crimped fibers. Got ready.

The core-sheath type composite staple fiber (wet heat adhesive fiber) and the side-by-side type composite staple fiber (coil crimped fiber) in a mass ratio of wet heat adhesive fiber / coil crimped fiber = 50/50. After blending, a card web having a basis weight of about 100 g / m ² was prepared by the card method, and five webs were stacked to obtain a card web having a total basis weight of 500 g / m ² .

  The card web was transferred to a belt conveyor equipped with a 50 mesh, 500 mm wide stainless steel endless wire mesh. In addition, the belt conveyor which has the same metal mesh is equipped in the upper part of the metal mesh of this belt conveyor, and it rotated in the same direction at the same speed, respectively, and used the belt conveyor which can adjust the space | interval of these metal meshes arbitrarily. .

  Next, the steam web is introduced into the steam jetting device provided in the lower belt conveyor, and 0.1 MPa of high-temperature steam is jetted from the device so as to pass in the thickness direction of the card web (perpendicularly). After the steam treatment, the nonwoven fabric structure was obtained by drying with hot air at 120 ° C. for 1 minute. In this steam spraying device, a nozzle is installed in the lower conveyor so as to spray high-temperature steam toward the web via a conveyor net, and a suction device is installed in the upper conveyor. Further, another jetting device, which is a combination of the arrangement of the nozzle and the suction device reversed, is installed on the downstream side in the web traveling direction of the jetting device, and steam treatment is performed on both the front and back sides of the web. did.

  In addition, the hole diameter of the water vapor | steam injection nozzle was 0.3 mm, and the water vapor | steam injection apparatus with which the nozzle was arranged in 1 row at 1 mm pitch along the width direction of the conveyor was used. The processing speed was 3 m / min, and the interval (distance) between the upper and lower conveyor belts on the nozzle side and the suction side was 30 mm. The nozzles were arranged on the back side of the conveyor belt so as to be almost in contact with the belt.

  The evaluation results of the obtained bulky fiber structure are shown in Table 1. The image which expanded the cross section of the obtained bulky fiber structure 25 times with the scanning electron microscope (SEM) is shown in FIG. From the photograph of FIG. 2, the obtained bulky fiber structure was entangled so that crimped fibers having an average curvature radius of 700 μm surrounded other fibers.

Example 2
A fiber structure was obtained in the same manner as in Example 1 except that the wet heat adhesive fiber and the coil crimped fiber were mixed in a ratio (mass ratio) of wet heat adhesive fiber / coil crimped fiber = 70/30. The evaluation results of the obtained fiber structure are shown in Table 1.

Example 3
After blending wet heat adhesive fibers and coil crimped fibers in a ratio (mass ratio) of wet heat adhesive fibers / coil crimped fibers = 70/30, a card web having a basis weight of about 100 g / m ² is produced by the card method. A fiber structure was obtained in the same manner as in Example 1 except that 15 webs were stacked to form a card web having a total basis weight of 1500 g / m ² . The evaluation results of the obtained fiber structure are shown in Table 1.

Example 4
A fiber structure was manufactured in the same manner as in Example 1 except that eight fiber webs were stacked to form a card web having a total basis weight of about 800 g / m ² and the interval between the upper and lower conveyor belts was 50 mm. The evaluation results of the obtained fiber structure are shown in Table 1.

Example 5
After blending wet heat adhesive fiber and coil crimped fiber in a ratio (mass ratio) of wet heat adhesive fiber / coil crimped fiber = 50/50, a card web having a basis weight of about 120 g / m ² is produced by the card method. Then, a fiber structure was produced in the same manner as in Example 1 except that this web was transferred to a belt conveyor as a single layer and the interval between the upper and lower conveyor belts was 10 mm. The evaluation results of the obtained fiber structure are shown in Table 1.

Example 6
A core-sheath type composite staple fiber having a core component made of polyethylene terephthalate and a sheath component made of a modified polyethylene terephthalate resin (“TJ04C2” manufactured by Teijin Fibers Ltd., fineness) A fiber structure was produced in the same manner as in Example 1 except that 2.2 dtex, fiber length 51 mm, and sheath component melting point 110 ° C. were used. Table 2 shows the evaluation results of the obtained fiber structure.

Example 7
A fiber structure in the same manner as in Example 6, except that the hydrophobic heat-adhesive fiber and the coil-crimped fiber are blended in a ratio (mass ratio) of hydrophobic heat-adhesive fiber / coil-crimped fiber = 70/30. Got. Table 2 shows the evaluation results of the obtained fiber structure.

Example 8
A fiber structure was obtained in the same manner as in Example 1 except that the wet heat adhesive fiber and the coil crimped fiber were mixed in a ratio (mass ratio) of wet heat adhesive fiber / coil crimped fiber = 30/70. Table 2 shows the evaluation results of the obtained fiber structure.

Comparative Example 1
An attempt was made to produce a fiber structure in the same manner as in Example 1 except that polyethylene terephthalate fiber (fineness: 3 dtex, fiber length: 51 mm) was used alone as the raw material fiber, but the polyethylene terephthalate fiber was not bonded in the wet heat treatment, Since it was still in the web state, it could not be handled as a sheet. Some of the web properties are shown in Table 2.

Comparative Example 2
A fiber structure was obtained in the same manner as in Example 1 except that the wet heat adhesive fiber and the coil crimped fiber were mixed in a ratio (mass ratio) of wet heat adhesive fiber / coil crimped fiber = 20/80. However, in this structure, the fibers were not sufficiently fixed with the wet heat-adhesive fibers, and when the compression recovery was repeated, the fibers dropped out and the form collapsed. Table 2 shows the evaluation results of the obtained fiber structure.

Example 9
A fiber structure was obtained in the same manner as in Example 1 except that the wet heat adhesive fiber and the coil crimped fiber were mixed in a ratio (mass ratio) of wet heat adhesive fiber / coil crimped fiber = 90/10. Table 2 shows the evaluation results of the obtained fiber structure.

  As is clear from the results of Tables 1 and 2, the fiber structures of Examples 1 to 9 are excellent in cushioning properties and compression recovery properties, have high breathability, have less fiber dropout, and have shape stability. It was an excellent cushion body. The fiber structure of Example 8 had slightly lower compression durability and rigidity than the fiber structures of Examples 1-7. Although the fiber structure of Example 9 was a fiber structure having very high form stability, the density was high and the flexibility was low as compared with the fiber structures of Examples 1-8.

FIG. 1 is a schematic diagram showing a method for measuring fiber curvature in the present invention. FIG. 2 is an electron micrograph (25 times) of a cross section of the bulky fiber structure obtained in Example 1.

Claims (8)

Bulky fiber in which a fiber comprising a heat-adhesive fiber and a crimped fiber having an average curvature radius of 0.3-2 mm is entangled to form a non-woven fiber structure, and the fiber is fixed by fusion of the heat-adhesive fiber A structure,
Obtained by a production method comprising a step of forming a fiber containing a heat-adhesive fiber and a crimped fiber, and a step of fusing the produced fiber web by heating and humidifying with high-temperature steam,
The thermal bonding fibers containing more than 25% by mass relative to entire structure, and in the structure section, in the cross section in the thickness direction, both the bonded fiber ratio in each of the regions divided into three equal in the thickness direction A bulky fiber structure that is 0.5 to 10%, and in which the bonding points of the fibers fused by the heat-bonding fibers are distributed substantially uniformly.   The average radius of curvature of the crimped fiber is 0.5 to 1 mm, and the crimped fiber is a parallel type or eccentric core-sheath type composite fiber composed of a polyalkylene arylate resin and a modified polyalkylene arylate resin. The bulky fiber structure according to claim 1.   A thermoplastic resin in which the heat-adhesive fiber has a melting point or softening point of 50 to 150 ° C. and a sheath portion composed of a wet heat-adhesive resin or a hydrophobic heat-adhesive resin, and a higher melting point or softening point than the heat-adhesive resin. The bulky fiber structure according to claim 1, wherein the bulky fiber structure is a core-sheath type composite fiber formed with a core portion made of a resin.   The bulky fiber structure according to any one of claims 1 to 3, wherein a ratio (mass ratio) of the heat-bonding fiber and the crimped fiber is the former / the latter = 90/10 to 30/70. In the cross section in the thickness direction, the fiber curvature rate in each region divided into three equal parts in the thickness direction is 1.1 or more, and the ratio between the maximum value and the minimum value of the fiber curvature rate in each region is 75, respectively. with at least%, claim 1-4 the bonded fiber ratio in each of the regions is from 2 to 10% both, and the ratio between the maximum value and the minimum value of the bonded fiber ratio in each region is 50% or more The bulky fiber structure according to any one of the above. The apparent density is 0.01 to 0.1 g / cm ³ , the air permeability by the Frazier method is 50 to 400 cm ³ / (cm ² · sec ), and the thermal conductivity is 0.03 to 0.07 W / m. In the behavior that is K and is compressed and recovered to 50% in accordance with JIS K6400-2, the ratio of 25% compressive stress in the recovery behavior to 25% compressive stress in the compression behavior is 30% or more Item 6. A bulky fiber structure according to any one of Items 1 to 5. Surface hardness by FO type durometer is 8-80, compression ratio to load of 0.5g / m ² is 60% or more, and repeated compression residual strain test of JIS K6400-4 Method B (constant displacement method) The bulky fiber structure according to any one of claims 1 to 6, wherein the return rate after repeated compression in accordance with (1) is 75% or more.   The production of a bulky fiber structure according to claim 1, comprising a step of forming a fiber containing a heat-adhesive fiber and a crimped fiber, and a step of fusing the produced fiber web by heating and humidifying with high-temperature steam. Method.