JP5086018B2 - Buffer material and manufacturing method thereof - Google Patents

Description

  The present invention relates to a cushioning material that can be used in vehicles such as automobiles, buildings such as roads, houses, factories, and the like, and can absorb or shield noise, heat, impact, and the like, and a method of manufacturing the same.

  Conventionally, fiber aggregates such as natural fibers and synthetic fibers have excellent sound-absorbing heat insulation properties, light weight, and breathability, etc., so sound absorption for reducing noise in the passenger compartment and living space and suppressing heat diffusion It is used as a heat insulating material or an impact absorbing material for absorbing an impact.

  Regarding a sound-absorbing heat insulating material for automobiles, for example, in Japanese Patent Application Laid-Open No. 2006-240408 (Patent Document 1), the surface of a core material composed of reinforcing fibers such as glass fibers and an olefin resin is composed of an olefin resin. Lightweight and sound-absorbing undercovers for automobiles covered with a reinforced layer have been proposed. However, since this under cover forms a reinforcing layer, the structure is complicated and the air permeability is low. Furthermore, since the olefin resin is mixed with the reinforcing fiber, the sound absorption is not sufficient.

Japanese Patent Laid-Open No. 9-226480 (Patent Document 2) discloses that main fibers, binder fibers, and fine fibers made of a thermoplastic resin are oriented substantially perpendicular to the sheet surface, and the fibers are aligned with each other. Is a pad formed of a sheet-like fiber structure heat-sealed, wherein the fiber structure has a density of 0.01 to 0.05 g / cm ³ and a dynamic spring constant of 0.1 × 10 ^{5 to} 0.00. An automotive silencer pad is disclosed that is 5 × 10 ⁵ N / m. In this document, a binder fiber made of a core-sheath type composite fiber having a low melting point copolyester as a sheath component is fused with hot air. However, with this silencer pad, fibers cannot be fused uniformly within the pad, and air permeability and moldability are reduced. Further, when the strength of the pad is improved, the fibers are fixed more than necessary, and the sound absorption is reduced. Furthermore, the pad structure is complicated and productivity is low.

Furthermore, in Japanese Patent Laid-Open No. 5-181486 (Patent Document 3), a synthetic fiber staple having a single fiber fineness of 5 denier or less is used as a raw material, and the average apparent density is 0.02 to 0 using at least 50% by weight of the raw material. A sound absorbing material composed of a fiber aggregate molded to 2 g / cm ³ , and having at least a modified cross-sectional fiber having a cross-sectional shape with a long outer periphery of the fiber compared to a circular outer periphery equivalent to the cross-sectional area of the fiber, A sound absorbing material containing 30% by weight or more is disclosed. This document describes that a core-sheath type low-melting polyester fiber is heat-bonded as a binder, and heated or dried with steam to form a fiber assembly. However, even with this sound absorbing material, the fibers are not fused uniformly within the fiber assembly, and the internal structure is rough, so that the moldability, sound absorbing property, and air permeability are not sufficient.

Moreover, regarding the heat insulating sound-absorbing material for buildings, Japanese Patent Application Laid-Open No. 2005-82987 (Patent Document 4) discloses heat insulation such as glass wool in a gap between a set of interior boards made of gypsum board or calcium silicate board. A partition wall structure filled or inserted with an endothermic material has been proposed. However, since glass fiber is used, a complicated structure for fixing the glass fiber is required, and productivity is lowered.
JP-A-2006-240408 (Claim 1, Example) JP-A-9-226480 (Claim 1, paragraph [0013], Example) Japanese Patent Laid-Open No. 5-181486 (Claim 1, paragraph [0010], Example) JP 2005-82987 A (Claim 1, paragraph [0029])

  Accordingly, an object of the present invention is to provide a cushioning material that can absorb or shield energy such as sound, heat, and impact, and has high moldability, and a method for manufacturing the same.

  Another object of the present invention is to provide a cushioning material that retains high form stability and is excellent in mechanical properties such as bending stress and toughness despite having air permeability, and a method for producing the same. It is in.

  Still another object of the present invention is to provide a shock-absorbing material that is excellent in light weight and has appropriate flexibility, and a method for producing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have used a molded article having a non-woven fiber structure in which fibers are appropriately bonded by wet heat adhesive fibers as a cushioning material, such as sound, heat, and impact. The present invention has been completed by discovering that it can absorb or shield the energy of the resin and has excellent moldability.

That is, the cushioning material of the present invention is a cushioning material that includes wet heat adhesive fibers and has a non-woven fiber structure, and is formed of a molded body in which fibers are fixed by fusion of the wet heat adhesive fibers. . In this buffer material, in the cross section in the thickness direction, the fiber adhesion rate in each region divided into three equal parts in the thickness direction is 75% or less, and the ratio of the minimum value to the maximum value of the fiber adhesion rate in each region is It may be 50% or more. Further, it has an apparent density of 0.05 to 0.7 g / cm ³ , has a maximum bending stress in at least one direction of 0.05 MPa or more, and is 1.5 times the bending amount indicating the maximum bending stress. The bending stress in the amount may be 1/5 or more with respect to the maximum bending stress. This buffer material has a thermal conductivity of about 0.03 to 0.1 W / (m · K) and an air permeability according to the Frazier method of about 0.1 to 300 cm ³ / (cm ² · sec). Also good. This buffer material further contains non-humid heat adhesive fibers, and the ratio (mass ratio) of the wet heat adhesive fibers to the non-humid heat adhesive fibers is wet heat adhesive fibers / non-humid heat adhesive fibers = 60 / 40-100. It may be about / 0. The wet heat adhesive fiber may contain an ethylene-vinyl alcohol copolymer. The non-wet heat adhesive fiber is a composite fiber in which a phase structure is formed of a plurality of resins having different thermal shrinkage rates, and the composite fiber may be crimped substantially uniformly with an average curvature radius of 20 to 200 μm. The shock-absorbing material of the present invention can be used as a sound-absorbing heat insulating material, a shock absorbing material, a partition material or the like.

  The present invention includes a step of forming a fiber containing wet heat adhesive fibers into a web, and a step of heat-treating the produced fiber web with high-temperature steam to fuse the fibers to obtain a molded body having a non-woven fiber structure. The manufacturing method of the said buffer material containing is also included.

  In the present specification, the “buffer material” means a material for blocking or weakening the propagation of energy by absorbing or shielding energy by sound, heat, impact, or the like. The cushioning material in the present invention is usually used as a buffering material such as partitioning a space as a plate-like molded body to inhibit the propagation of noise or suppress the release of heat.

  Since the cushioning material of the present invention has a non-woven fiber structure in which fibers are appropriately bonded by wet heat adhesive fibers, it can absorb or shield sound, heat, and impact energy. That is, it is excellent in sound absorption, heat insulation, and shock absorption. Further, it has high moldability and can be easily formed into a complicated shape by press molding or the like. In addition, even within the non-woven fiber structure, the fibers are evenly fused, so it retains high morphological stability despite mechanical properties such as bending stress and toughness. Excellent characteristics. In addition, it is low in density and excellent in light weight, and has moderate flexibility. Furthermore, this cushioning material can be substantially composed of only fibers, and it is not necessary to add chemical binders or special chemicals. Therefore, without using components that generate harmful components (such as volatile organic compounds such as formaldehyde), It can be easily manufactured.

[Buffer material]
The cushioning material of the present invention contains wet heat adhesive fibers and has a non-woven fiber structure. In particular, the cushioning material of the present invention is composed of a molded body in which fibers are fixed by fusion of the wet heat-adhesive fibers, and has not only a high sound-absorbing and shock-absorbing property specific to the fiber structure, but also a non-woven fiber structure. By adjusting the arrangement of the fibers and the bonding state between these fibers, it cannot be obtained with ordinary nonwoven fabrics. “Bending behavior (having a high bending stress and bending beyond the point where the maximum bending stress is shown) Even if stress is retained, behavior to try to recover when the stress is released), lightness, and surface hardness (even if a force is applied to the thickness direction by applying a load to the surface, it does not easily deform) Characteristics) ”, and it is more difficult to break, and at the same time, it retains form retention and air permeability.

  Such a cushioning material, as will be described later, causes high-temperature (superheated or heated) water vapor to act on the web containing the wet heat-adhesive fiber, and exhibits an adhesive action at a temperature below the melting point of the wet heat adhesive fiber. It can be obtained by partially bonding each other. That is, it is obtained by point-bonding or partial-bonding single fibers and bundle-like bundled fibers so as to form a “scrum” while holding moderately small voids under wet heat.

(Wet heat adhesive fiber)
The wet heat adhesive fiber is composed of at least a wet heat adhesive resin. The wet heat adhesive resin only needs to be able to flow or easily deform at a temperature that can be easily realized by high-temperature steam and to exhibit an adhesive function. Specifically, a thermoplastic resin that is softened with hot water (for example, about 80 to 120 ° C., particularly about 95 to 100 ° C.) and can be self-adhered or bonded to other fibers, for example, a cellulose-based resin (C such as methylcellulose) _1-3 alkylcelluloses, hydroxyalkyl C _1-3 alkyl celluloses such as hydroxypropyl cellulose, carboxy C _1-3 alkyl cellulose or a salt thereof, such as carboxymethyl cellulose), polyalkylene glycol resin (polyethylene oxide, poly C ₂ such as polypropylene oxide _-4 alkylene oxide), polyvinyl resins (polyvinyl pyrrolidone, polyvinyl ether, vinyl alcohol polymers, polyvinyl acetals, etc.), acrylic copolymers and alkali metal salts thereof [(meth) acrylic acid, (meth) acrylamide, etc. Copolymers containing units composed of any acrylic monomers or their salts], modified vinyl copolymers (such as vinyl monomers such as isobutylene, styrene, ethylene, vinyl ether, and maleic anhydride) Copolymer with unsaturated carboxylic acid or its anhydride or salt thereof), polymer with hydrophilic substituent introduced (polyester, polyamide, polystyrene or salt with introduced sulfonic acid group, carboxyl group, hydroxyl group, etc.) Etc.), 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 or water-soluble polymer. 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. %. When the saponification degree 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.

  The cross-sectional shape (cross-sectional shape perpendicular to the fiber length direction) of the wet 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. The wet heat adhesive fiber may be a composite fiber composed of a plurality of resins including at least a wet heat adhesive resin. The composite fiber only needs to have the wet heat adhesive resin on at least a part of the fiber surface, but from the viewpoint of adhesiveness, the wet heat adhesive resin continuously occupies at least a part of the surface in the length direction. Is preferred.

  Examples of the cross-sectional structure of the composite fiber in which the wet heat adhesive fiber occupies the surface include a core-sheath type, a sea-island type, a side-by-side type, a multilayer bonding type, a radial bonding type, and a random composite type. Among these cross-sectional structures, the core-sheath structure (that is, the sheath part is wet-heat-adhesive, which is a structure in which the wet-heat adhesive resin occupies the entire surface continuously in the length direction because it is a highly adhesive structure. A core-sheath structure made of resin is preferred.

  In the case of a composite fiber, wet heat adhesive resins may be combined with each other, but may be combined with non-wet heat adhesive resins. Non-wet heat adhesive resins include water-insoluble or hydrophobic resins such as polyolefin resins, (meth) acrylic resins, vinyl chloride resins, styrene resins, polyester resins, polyamide resins, polycarbonate resins, Examples include polyurethane resins and thermoplastic elastomers. These non-wet heat adhesive resins can be used alone or in combination of two or more.

  Among these non-wet heat adhesive resins, from the viewpoint of heat resistance and dimensional stability, resins having a melting point higher than that of wet heat adhesive resins (particularly ethylene-vinyl alcohol copolymers), such as polypropylene resins and polyester resins. Resins and polyamide resins, particularly polyester resins and polyamide resins are preferred from the standpoint of excellent balance between heat resistance and fiber-forming properties.

Polyester resins include aromatic polyester resins such as poly C _2-4 alkylene arylate resins (polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), especially polyethylene such as PET. A terephthalate resin is preferred. In addition to the ethylene terephthalate unit, the polyethylene terephthalate resin is not limited to other dicarboxylic acids (for example, isophthalic acid, naphthalene-2,6-dicarboxylic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid, bis (carboxyphenyl) ethane. , 5-sodium sulfoisophthalic acid, etc.) and diols (for example, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, Units composed of polyethylene glycol, polytetramethylene glycol, etc.) may be included at a ratio of about 20 mol% or less.

  Polyamide resins include polyamides 6, polyamides 66, polyamides 610, polyamides 10, polyamides 12, polyamides 6-12 and other aliphatic polyamides and copolymers thereof, half-synthesized from aromatic dicarboxylic acids and aliphatic diamines. Aromatic polyamide is preferred. These polyamide-based resins may also contain other copolymerizable units.

  In the case of a composite fiber composed of a wet heat adhesive resin and a non-wet heat adhesive resin (fiber-forming polymer), the ratio (mass ratio) of both can be selected according to the structure (for example, core-sheath structure). The wet heat adhesive resin is not particularly limited as long as it exists on the surface. For example, wet heat adhesive resin / non-wet heat adhesive resin = 90/10 to 10/90 (for example, 60/40 to 10/90), preferably It is about 80/20 to 15/85, more preferably about 60/40 to 20/80. If the proportion of wet heat adhesive resin is too large, it will be difficult to ensure the strength of the fiber, and if the proportion of wet heat adhesive resin is too small, it will be difficult to have the wet heat adhesive resin continuously in the length direction of the fiber surface. Thus, the wet heat adhesiveness is lowered. This tendency is the same when the wet heat adhesive resin is coated on the surface of the non-wet heat adhesive fiber.

  The average fineness of the wet 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 in this range, the balance between the strength of the fiber and the expression of wet heat adhesion is excellent.

  The average fiber length of the wet heat adhesive fibers can be selected, for example, from a range of about 10 to 100 mm, preferably 20 to 80 mm, 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 molded body is improved.

  The crimp rate of the wet heat adhesive fiber is, for example, about 1 to 50%, preferably 3 to 40%, more preferably about 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.

(Other fibers)
The cushioning material may further contain non-wet heat adhesive fibers. Non-wet heat adhesive fibers include polyester fibers (polyethylene terephthalate fibers, polytrimethylene terephthalate fibers, polybutylene terephthalate fibers, aromatic polyester fibers such as polyethylene naphthalate fibers), polyamide fibers (polyamide 6, polyamide 66, Aliphatic polyamide fibers such as polyamide 11, polyamide 12, polyamide 610, polyamide 612, semi-aromatic polyamide fibers, aromatic polyamide fibers such as polyphenylene isophthalamide, polyhexamethylene terephthalamide, poly p-phenylene terephthalamide, etc. ), Polyolefin fibers (poly C _2-4 olefin fibers such as polyethylene and polypropylene), acrylic fibers (acrylonitrile-vinyl chloride copolymer, etc.) Acrylonitrile fibers having rilonitrile units), polyvinyl fibers (polyvinyl acetal fibers, etc.), polyvinyl chloride fibers (polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylonitrile copolymer fibers, etc.) ), Polyvinylidene chloride fiber (fiber such as vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-vinyl acetate copolymer), polyparaphenylene benzobisoxazole fiber, polyphenylene sulfide fiber, cellulosic fiber (for example, rayon fiber) And acetate fibers). These non-wet heat adhesive fibers can be used alone or in combination of two or more.

  These non-wet heat adhesive fibers can be appropriately selected and used according to the type of the buffer material. When importance is attached to mechanical properties such as hardness, it is preferable to use hydrophilic fibers with high hygroscopicity, for example, polyvinyl fibers or cellulose fibers, particularly cellulose fibers. Cellulosic fibers include natural fibers (cotton, wool, silk, hemp, etc.), semi-synthetic fibers (acetate fibers such as triacetate fiber), regenerated fibers (rayon, polynosic, cupra, lyocell (for example, registered trademark name: “ Tencel "etc.)). Among these cellulosic fibers, for example, semi-synthetic fibers such as rayon can be suitably used, and when combined with wet heat adhesive fibers containing an ethylene-vinyl alcohol copolymer, the affinity with wet heat adhesive fibers is high. As the shrinkage progresses, the adhesiveness also improves, and in the present invention, a molded body having a relatively high density and high mechanical properties can be obtained.

  On the other hand, when heat insulation sound absorption and impact absorption are more important than moldability and form stability, hydrophobic fibers with low hygroscopicity, such as polyolefin fibers, polyester fibers, polyamide fibers, especially various properties It is preferable to use a polyester fiber (polyethylene terephthalate fiber or the like) having an excellent balance. When these hydrophobic fibers are combined with wet heat adhesive fibers containing an ethylene-vinyl alcohol copolymer, the gap between the fibers increases, and the number of fibers that can vibrate freely without fusing increases. Thus, a shock absorbing material with high shock absorption can be obtained.

  The average fineness and average fiber length of the non-wet heat adhesive fibers are the same as those of the wet heat adhesive fibers.

  Furthermore, the phase structure is composed of a plurality of resins having different thermal shrinkage rates (or thermal expansion coefficients) among hydrophobic fibers, such as when the cushioning material is used for applications that particularly require flexibility and shock absorption. It is preferable to use a formed conjugate fiber (latently crimped conjugate fiber).

  The latent crimpable conjugate fiber is a fiber having an asymmetric or layered (so-called bimetal) structure that causes crimping by heating due to a difference in thermal contraction rate (or thermal expansion rate) of a plurality of resins (latent crimped fiber) ). A plurality of resins usually have different softening points or melting points. As the plurality of resins, for example, the non-wet heat adhesive resin exemplified in the section of the wet heat adhesive fiber can be used. Among them, a non-wet heat adhesive resin (or heat-resistant hydrophobic resin or non-aqueous resin) having a softening point or a melting point of 100 ° C. or higher from the viewpoint that the fiber does not melt and soften even when heat-treated with high-temperature steam. For example, a polypropylene-based resin, a polyester-based resin, and a polyamide-based resin are preferable, and an aromatic polyester-based resin and a polyamide-based resin are particularly preferable from the viewpoint of excellent balance between heat resistance and fiber forming property. In the present invention, the resin exposed on the surface of the composite fiber is preferably a non-wet heat adhesive fiber so that the fusion by the composite fiber does not occur even when treated with high-temperature steam.

  The plurality of resins constituting the composite fiber 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, the composite fiber is a combination of an aromatic polyester resin, particularly a polyalkylene arylate resin (a) and a modified polyalkylene arylate resin (b) because it is easy to produce latent crimpable conjugate fibers. It may be a combination. In particular, in the present invention, a type that develops crimp after web formation is preferable, and the combination is also preferable in this respect. By producing crimp after the web formation, the fibers can be efficiently entangled and the web shape can be maintained with a smaller number of fusion points, so that high flexibility can be realized.

The polyalkylene arylate resin (a) is composed of an aromatic dicarboxylic acid (such as symmetric aromatic dicarboxylic acid such as terephthalic acid or naphthalene-2,6-dicarboxylic acid) and an alkanediol component (such as ethylene glycol or butylene glycol such as C _{3- 6} alkanediol etc.) and 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 crimps are not expressed, and the form stability and stretchability of the nonwoven fiber aggregate after the crimps are reduced. On the other hand, if the proportion of the copolymer component is too high, the crimping performance will be high, but it will be difficult to spin stably.

  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 cross-sectional shape of the composite 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 shape, elliptical shape, polygonal shape, 3-14 leaf shape, It is not limited to T-shape, H-shape, V-shape, dogbone (I-shape), etc.], and may be a hollow cross-section, but is usually a round cross-section.

  As a cross-sectional structure of the composite fiber, a phase structure formed in 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), a radial type (radial bonding type) ), Hollow radiation type, block type, random composite type and the like. Among these cross-sectional structures, the structure in which the phase portions are adjacent (so-called bimetal structure), or the structure in which the phase structure is asymmetrical, for example, an eccentric core-sheath type, in parallel, because it is easy to develop spontaneous crimping by heating. A mold structure is preferred.

  If the composite fiber has a core-sheath type structure such as an eccentric core-sheath type, the core portion is not damaged if it has a heat shrinkage difference with the non-wet heat adhesive resin of the sheath portion located on the surface. Consists of wet heat adhesive resin (for example, vinyl alcohol polymers such as ethylene-vinyl alcohol copolymer and polyvinyl alcohol) and thermoplastic resin having a low melting point or softening point (for example, polystyrene, low density polyethylene, etc.) May be.

  The average fineness of the composite fiber can be selected from a range of, for example, about 0.1 to 50 dtex, preferably 0.5 to 10 dtex, and more preferably 1 to 5 dtex (particularly 1.5 to 3 dtex). If the fineness is too thin, it is difficult to produce the fiber itself, and it is difficult to secure the fiber strength. Moreover, it becomes difficult to express a beautiful coiled crimp in the step of expressing crimp. On the other hand, if the fineness is too thick, the fiber becomes stiff and it is difficult to express sufficient crimp.

  The average fiber length of the composite 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 40 to 60 mm). If the fiber length is too short, it becomes difficult to form a fiber web, and in addition, in the step of developing crimps, entanglement between fibers becomes insufficient, and it becomes difficult to ensure strength and stretchability. In addition, if the fiber length is too long, it becomes difficult to form a fiber web with a uniform basis weight, and a lot of fibers are entangled at the time of web formation, which interferes with each other when crimping occurs. Therefore, it becomes difficult to develop flexibility.

  By applying heat treatment to this composite fiber, crimp is developed (appears) and becomes a fiber having a substantially coiled (spiral or helical spring-shaped) three-dimensional crimp.

  The number of crimps before heating (mechanical crimp number) is, for example, about 0 to 30 pieces / 25 mm, preferably about 1 to 25 pieces / 25 mm, and more preferably about 5 to 20 pieces / 25 mm. The number of crimps after heating is, for example, 30 pieces / 25 mm or more (for example, 30 to 200 pieces / 25 mm), preferably about 35 to 150 pieces / 25 mm, and more preferably about 40 to 120 pieces / 25 mm. It may be about 45 to 120 pieces / 25 mm (especially 50 to 100 pieces / 25 mm).

  Since the molded body containing the latent crimpable fiber is crimped with high-temperature steam, the composite fiber has a characteristic that the crimp of the composite fiber appears substantially uniformly inside the molded body. Specifically, for example, in the cross section in the thickness direction, the number of fibers forming one or more coil crimps in the central portion (inner layer) of each region divided in three in the thickness direction is, for example, 5-50 pieces / 5 mm (surface length) · 0.2 mm (thickness), preferably 5-40 pieces / 5 mm (surface direction) · 0.2 mm (thickness), more preferably 10-40 pieces / thickness. It is 5 mm (surface direction) · 0.2 mm (thickness). In the present invention, most of the crimped fibers and the inside of the molded body (from the vicinity of the surface of the molded body to the central portion) have a uniform number of crimps. It has flexibility and practical strength. 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 molded body.

  As described above, the crimped fiber constituting the molded body has a substantially coil-shaped crimp after the crimp is developed. The average curvature radius of a circle formed by the coil of crimped fibers can be selected from a range of about 10 to 250 μm, for example, for example, 20 to 200 μm (for example, 50 to 200 μm), preferably 50 to 160 μm (for example, 60 to 150 μm), more preferably about 70 to 130 μm. Here, the average radius of curvature is an index representing the average size of the circle formed by the coil of crimped fibers, and when this value is large, the formed coil has a loose shape, in other words It means having a shape with a small number of crimps. Further, when the number of crimps is small, the entanglement between the fibers is also reduced, which is disadvantageous for exhibiting flexibility. Conversely, when a coiled crimp having an average radius of curvature that is too small is manifested, the fibers are not sufficiently entangled, making it difficult to ensure web strength, and also exhibiting such a crimp. Production of latent crimpable conjugate fibers is also very difficult.

  In the composite fiber crimped into a coil shape, the average pitch of the coil is, for example, about 0.03 to 0.5 mm, preferably about 0.03 to 0.3 mm, and more preferably about 0.05 to 0.2 mm.

  The ratio (mass ratio) between the wet heat adhesive fiber and the non-wet heat bond fiber is also determined according to the type and use of the cushioning material: wet heat bond fiber / non-wet heat bond fiber = 100/0 to 10/90 (for example, The range can be selected from about 90/10 to 20/80). As the ratio of both, when the ratio of wet heat adhesive fibers increases, the adhesion point increases, so mechanical properties such as surface hardness and bending behavior improve, and when the ratio of non-humid heat adhesive fibers increases, Since voids increase and free fibers also increase, heat insulation sound absorption tends to be improved. Moreover, since the fixing force of the fiber is also reduced, the impact absorbability and flexibility are also improved. In the present invention, in particular, from the viewpoint of strength and formability required for members of buildings and vehicles, the ratio (mass ratio) of both is wet heat adhesive fiber / non-wet heat adhesive fiber = 100/0. 60/40 (for example, 99/1 to 60/40), preferably 100/0 to 70/30 (for example, 95/5 to 70/30), more preferably 100/0 to 80/20 (particularly 100 / 0 to 90/10).

  The molded body (or fiber) is further added with conventional additives such as stabilizers (heat stabilizers such as copper compounds, ultraviolet absorbers, light stabilizers, antioxidants, etc.), dispersants, thickeners, fine particles. , Colorant, Antistatic agent, Flame retardant, Plasticizer, Lubricant, Crystallization rate retarding agent, Lubricant, Antibacterial agent, Insect / Anticide agent, Antifungal agent, Matting agent, Animal heat agent, Fragrance, Fluorescent whitening An agent, a wetting agent, a plasticizer and the like may be contained. These additives can be used alone or in combination of two or more. These additives may be carried on the surface of the molded body or may be contained in the fiber.

(Characteristics of cushioning material)
The cushioning material of the present invention has a non-woven fiber structure obtained from the web composed of the fibers, the shape of which can be selected according to the application, and may be circular, elliptical, or polygonal in cross section. However, it is usually in the form of a sheet or plate.

  Furthermore, in order to have a non-woven fiber structure having a high hardness (morphological stability) and a good balance between heat-absorbing sound absorption and shock absorption and light weight (low density) in the cushioning material, It is necessary that the arrangement state and the adhesion state of the fibers constituting the fiber web are appropriately adjusted. That is, it is desirable that the fibers constituting the fiber web are arranged so as to intersect each other while being arranged substantially parallel to the surface of the fiber web (non-woven fiber). Furthermore, it is preferable that the molded body constituting the buffer material is fused at the intersection where the fibers intersect. In particular, a molded body that requires high form stability forms bundled fused fibers that are fused in a bundle of several to several tens at a portion where fibers other than the intersection are arranged substantially in parallel. It may be. These fibers form a “scrum” by partially forming a fused structure at the intersection of single fibers, the intersection of bundle fibers, or the intersection of single fibers and bundle fibers A structure (a structure in which fibers are bonded at an intersection and entangled like a mesh, or a structure in which fibers are bonded at an intersection to constrain adjacent fibers to each other) to achieve the desired bending behavior, surface hardness, etc. it can. In the present invention, it is desirable that such a structure is distributed substantially uniformly along the surface direction and the thickness direction of the fiber web.

  The phrase “arranged approximately parallel to the fiber web surface” as used herein indicates a state where there are no repeated portions where a large number of fibers are locally arranged along the thickness direction. More specifically, when an arbitrary cross section of the fiber web of the formed body is observed with a microscope, the existence ratio (number ratio) of fibers continuously extending in the thickness direction over 30% of the thickness of the fiber web. Is 10% or less (especially 5% or less) with respect to all the fibers in the cross section.

  Fibers are arranged parallel to the fiber web surface when there are many fibers oriented in the thickness direction (perpendicular to the web surface) and the fiber arrangement is disturbed around the fiber web. This is because an unnecessarily large void is generated in the woven fiber, and the bending strength and surface hardness of the molded body are reduced. Therefore, it is preferable to reduce this gap as much as possible. For this purpose, it is desirable to arrange the fibers as parallel to the fiber web surface as possible.

  In addition, when the web is entangled by means such as a needle punch, a high-density molded body can be easily manufactured. Furthermore, when the fibers are entangled before being wet-heat bonded, the shape of the fibers before bonding is maintained, so that it becomes easy to produce a molded product having a large thickness, which is advantageous in terms of production efficiency. However, the entanglement of the fibers by the needle punch or the like is disadvantageous in that the fibers are arranged in parallel to the fiber web surface. Furthermore, since the density of the molded body is increased by the entanglement, it is difficult to manufacture a low-density and lightweight molded body. Therefore, from the viewpoint of arranging the fibers in parallel, it is preferable that the degree of fiber entanglement is reduced or not entangled.

  In particular, when a load is applied in the thickness direction of the molded body when the molded body is in the form of a sheet or plate, if there is a large void, the void is crushed by the load and the surface of the molded body is easily deformed. . Further, when this load is applied to the entire surface of the molded body, the thickness tends to be reduced as a whole. Such a problem can be avoided if the molded body itself is a resin filling without voids, but the liquid permeability is lowered.

  On the other hand, in order to reduce the deformation in the thickness direction due to the load, it is conceivable to make the fibers thinner and more densely filled with the fibers. However, the bending stress decreases. In order to secure bending stress, it is necessary to increase the fiber diameter to some extent. However, if thick fibers are simply mixed, large voids are easily formed near the intersections of the thick fibers and deformed in the thickness direction. It becomes easy to do.

  Therefore, the cushioning material of the present invention has a low density, and the fibers are aligned with each other in parallel along the surface direction of the web and dispersed (or the fiber direction is directed in a random direction) so that the fibers are mutually aligned. By crossing and adhering at the intersection, a small gap is generated to ensure liquid permeability and high water absorption. Furthermore, an appropriate surface hardness is ensured by such a continuous fiber structure. In particular, when a bundle of fibers fused in parallel in the fiber length direction is formed in a place where the fibers are aligned in parallel without intersecting with other fibers, compared to the case where the fibers are composed of only single fibers. High bending strength can be secured mainly. When a molded body having high hardness and strength is desired, several bundles are formed at the portion where each fiber is arranged in a bundle between the intersections while adhering at the intersections where the fibers intersect each other. It is preferable to form a fiber. Such a structure can be confirmed from the existence state of the single fiber when the cross section of the compact is observed.

  Furthermore, in the cushioning material of the present invention, the fiber constituting the nonwoven fiber structure has a fiber adhesion rate of, for example, 75% or less (for example, 1 to 75%), preferably 3 to 3 by fusing the wet heat adhesive fibers. It is bonded at 70%, more preferably 5-60% (especially 10-50%). 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 a ratio of a plurality of fibers fused to each other (a ratio of fibers fused by fusing) is small.

  In the present invention, the fibers constituting the non-woven fiber structure are bonded at the contact points of the respective fibers. In order to express a large bending stress with as few contacts as possible, this bonding point is the thickness direction. In addition, it is preferably distributed uniformly from the surface of the molded body to the inside (center) and the back surface. When the adhesion points are concentrated on the surface or inside, not only is it difficult to ensure excellent mechanical properties and moldability, but also the shape stability in the portion where the adhesion points are small is lowered.

  Therefore, in the cross section in the thickness direction of the molded body, it is preferable that the fiber adhesion rate in each region divided in three in the thickness direction is in the above range. 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%, more preferably 60 to 98% (especially 70 to 97%). In the present invention, since the fiber adhesion rate has such uniformity in the thickness direction, the hardness, bending strength, bending resistance and toughness are excellent even though the fiber adhesion area is low. . Furthermore, since the bonding area of the fibers is low, there are many fibers that can vibrate freely and the sound absorption is high.

  As described above, in the cushioning material of the present invention, not only fusion by wet heat adhesive fibers is uniformly dispersed and point-bonded, but also the point adhesion of these points is short (for example, several tens to several 100 μm), and the network structure is densely stretched. Due to such a structure, the cushioning material of the present invention has high followability to strain due to the flexibility of the fiber structure even when an external force acts, and at each fusion point of finely dispersed fibers. Since the external force is dispersed and reduced, it can be estimated that high folding resistance and toughness are expressed. On the other hand, the conventional porous molded body, foam, and the like form a continuous interface around the pores, so that the external force is received in a large area compared to the cushioning material of the present invention, It can be presumed that distortion is likely to occur, and folding resistance and toughness are lowered.

In the cushioning material of the present invention, the existence frequency of single fibers (single fiber end faces) in the cross section in the thickness direction is not particularly limited. For example, when high heat insulation sound absorption or shock absorption is required, any of the cross sections the frequency of occurrence of single fibers present in 1 mm ² is an average of 100 pieces / mm ² or more (e.g., about 100-300 / mm ²⁾ may be. On the other hand, when mechanical properties are required rather than heat insulating sound absorption and light weight, the presence frequency of single fibers is, for example, an average of 100 / mm ² or less, preferably 60 / mm ² or less (for example, 1 ˜60 pieces / mm ² ), more preferably 25 pieces / mm ² or less (for example, 3 to 25 pieces / mm ² ). When the presence frequency of the single fiber is too high, the fusion of the fibers is small and the strength of the molded body is lowered. If the frequency of single fibers exceeds 100 fibers / mm ² , bundle fusion of fibers decreases, making it difficult to ensure high bending strength. Furthermore, in the case of a plate-shaped molded body, it is preferable that the fibers fused in a bundle shape are thin in the thickness direction of the molded body and have a wide shape in the surface direction (length direction or width direction).

In the present invention, the existence frequency of the single fiber is measured as follows. That is, the range corresponding to 1 mm ² selected from the scanning electron microscope (SEM) photograph of the cross section of the compact is observed, and the number of single fiber cross sections is counted. Arbitrary several places (for example, 10 places selected at random) are observed in the same manner, and the average value per unit area of the single fiber end face is defined as the existence frequency of single fibers. At this time, all the number of fibers in a single fiber state are counted in the cross section. That is, in addition to fibers that are completely in a single fiber state, even if a plurality of fibers are fused, a fiber that is separated from the fused portion in the cross section and is in a single fiber state is counted as a single fiber.

  The wet heat-adhesive fibers in the molded body can prevent the fibers from dropping off from the molded body due to fiber slipping or the like because the fibers do not penetrate the molded body in the thickness direction. The production method for arranging the wet heat adhesive fibers in this way is not particularly limited, but a means for laminating a plurality of shaped bodies in which the wet heat adhesive fibers are entangled and performing wet heat adhesion is simple and reliable. Moreover, the fiber which penetrates in the thickness direction of a molded object can be reduced significantly by adjusting the relationship between fiber length and the thickness of a molded object. From such points, the thickness of the molded body is 10% or more (for example, 10 to 1000%), preferably 40% or more (for example, 40 to 800%), more preferably 60% or more with respect to the fiber length. (For example, 60 to 700%), particularly 100% or more (for example, 100 to 600%). By such adjustment, the dropout of fibers from the molded body can be suppressed without lowering the mechanical strength such as bending stress of the molded body.

  As described above, the buffer material of the present invention is affected by the density and mechanical properties depending on the ratio and the presence state of the bundle-like fused fibers. The fiber adhesion rate indicating the degree of fusion can be easily measured based on the number of bonded fiber cross sections in a predetermined region by taking a photograph of an enlarged cross section of the cushioning material using SEM. However, when fibers are fused in a bundle, each fiber is fused in a bundle or at an intersection, making it difficult to observe as a single fiber, especially when the density is high. easy. In this case, for example, when the cushioning material of the present invention is bonded with a core-sheath type composite fiber formed of a sheath part made of wet heat adhesive fiber and a core part made of a fiber-forming polymer. The fiber adhesion rate can be measured by releasing the adhesion of the bonded portion by means such as melting or washing and comparing it with the cut surface before the release. On the other hand, in the present invention, as an index reflecting the degree of fiber fusion, the area ratio occupied by the cross section formed by the fiber and the bundle of fiber bundles in the cross section (thickness direction cross section) of the molded body after molding, that is, fiber filling Rate can also be used. The fiber filling rate in the cross section in the thickness direction is, for example, 20 to 80%, preferably 20 to 60%, and more preferably about 30 to 50%. If the fiber filling rate is too small, there are too many voids in the molded body, making it difficult to ensure the desired surface hardness and bending stress. On the other hand, if it is too large, the surface hardness and bending stress can be sufficiently secured, but it becomes very heavy and the liquid permeability tends to decrease.

The cushioning material of the present invention (particularly, a molded product in which fibers are fused in a bundle and the frequency of single fibers is 100 pieces / mm ² or less) is concave due to a load even if it is plate-shaped (board-shaped). It is desirable to have a surface hardness that is difficult to be deformed. As such an index, it can be evaluated by the hardness by the durometer hardness test of E type and FO type (test in accordance with JIS K6253 "Testing method for hardness of vulcanized rubber and thermoplastic rubber"). In E type, it is 30 or more, for example, Preferably it is 40-100, More preferably, it is about 50-80. On the other hand, in FO type, it is 40 or more, for example, Preferably it is 50 or more, More preferably, it is about 60-100 (especially 70-100). If this hardness is too small, it is likely to be deformed by a load applied to the surface.

  The molded body containing such bundled fused fibers has a low frequency of bundled fused fibers in order to balance the thermal insulation sound absorption and shock absorption, bending strength, surface hardness and lightness in a high dimension. In addition, it is preferable that the fibers are bonded at a high frequency at the intersection of the fibers (bundle fibers and / or single fibers). However, if the fiber adhesion rate is too high, the distances between the bonded points are too close to each other, the heat insulating sound absorbing property, the shock absorbing property, and the flexibility are lowered, and it becomes difficult to eliminate distortion due to external stress. For this reason, the molded body needs to have a fiber adhesion rate of 75% or less. Since the fiber adhesion rate is not too high, the fiber can freely vibrate in the molded body, a passage by a fine gap can be secured, and lightness and air permeability can be improved. Therefore, in order to develop large sound-absorbing heat insulating properties, bending stress, surface hardness and air permeability with as few contacts as possible, the fiber adhesion rate increases in the thickness direction from the molded body surface to the inside (center) and back surface. It is preferable to distribute uniformly along. When the adhesion points are concentrated on the surface or inside, it is difficult to ensure air permeability in addition to the above bending stress and form stability.

  Therefore, in the cushioning material of the present invention, it is preferable that the fiber filling rate in each region divided into three equal parts in the thickness direction is in the above range in the cross section in the thickness direction. Furthermore, the ratio (minimum value / maximum value) of the minimum value to the maximum value of the fiber filling rate in each region is 50% or more (for example, 50 to 100%), preferably 60 to 99%, more preferably 70 to 98%. Degree. In the present invention, if the fiber filling rate is uniform in the thickness direction, the bending strength, folding resistance, toughness and the like are excellent. The fiber filling rate in the present invention can be measured from a SEM photograph by a method using an image analyzer.

  The cushioning material of the present invention is also characterized by high toughness and bending stress and exhibiting excellent bending behavior. In the present invention, in order to express this bending behavior, the repulsive force of the sample generated when the sample is gradually bent is measured according to JIS K7017 “Fiber-Reinforced Plastics—How to Obtain Bending Properties”, and the maximum stress (peak stress) is measured. ) As a bending stress and used as an index of bending behavior. That is, the larger the bending stress, the harder the molded body, and the more the bending amount (displacement) until the measurement object breaks, the better the curved body.

  The buffer material of the present invention has a maximum bending stress in at least one direction (preferably in all directions) of 0.05 MPa or more (for example, 0.05 to 100 MPa), preferably 0.1 to 30 MPa, more preferably 0. It may be about 2 to 20 MPa. Furthermore, in the case of having a high bending stress, such as a molded body containing bundled fused fibers (a plurality of fibers fused in a bundled form), the maximum bending stress is 2 MPa or more, preferably 5 to 100 MPa, Preferably, it may be about 10-60 MPa. If the maximum bending stress is too small, it is easily broken by its own weight or a slight load when used in a plate shape. Further, if the maximum bending stress is too high, it becomes too hard, and if it is bent beyond the peak of the stress, it is easily broken and broken. In addition, in order to obtain hardness exceeding 100 MPa, it is necessary to increase the density of the molded body, and it is difficult to ensure light weight and liquid permeability.

  Looking at the correlation between the bending amount (displacement) and the bending stress caused by the bending amount, the stress increases as the bending amount increases. For example, the bending amount increases approximately linearly. In the buffer material of the present invention, when the measurement sample reaches a specific bending amount, the stress gradually decreases thereafter. That is, when the amount of bending and the stress are graphed, a correlation is shown in which an upward convex parabola is drawn. The buffer material of the present invention may have a so-called “stickiness (or toughness)” without causing a rapid stress drop even when the bending material exceeds the maximum bending stress (bending stress peak) and is further bent. One of the features. In the present invention, as an index representing such “stickiness”, the bending stress remaining in a state exceeding the bending amount (displacement) at the peak of the bending stress can be used. That is, the buffer material of the present invention has a maximum bending stress that is a stress when bent to a displacement that is 1.5 times the amount of bending that indicates the maximum bending stress (hereinafter sometimes referred to as “1.5 times displacement stress”). It is only necessary to maintain 1/5 or more (for example, 1/5 to 1) of the stress, for example, 1/3 or more (for example, 1/3 to 9/10), preferably 2/5 or more (for example, 2/5 to 9/10), more preferably 3/5 or more (for example, 3/5 to 9/10). The double displacement stress is 1/10 or more (for example, 1/10 to 1) of the maximum bending stress, preferably 3/10 or more (for example, 3/10 to 9/10), more preferably 5/10. You may maintain above (for example, 5 / 10-9 / 10).

  The cushioning material of the present invention can ensure high lightness due to the gap generated between the fibers. Moreover, since these voids are not independent voids but are continuous, they have high air permeability. Such a structure is a structure that is extremely difficult to produce by conventional hardening methods such as a method of impregnating a resin and a method of forming a film-like structure by closely adhering surface portions. .

That is, the buffer material of the present invention has a low density, specifically, the apparent density can be selected from the range of about 0.05 to 0.7 g / cm ³ , From the viewpoint of the balance, for example, 0.06 to 0.5 g / cm ³ , preferably 0.07 to 0.4 g / cm ³ , and more preferably about 0.08 to 0.35 g / cm ³ (particularly 0. 1 to 0.3 g / cm ³ ). If the apparent density is too low, the heat-absorbing sound absorption and shock absorption are high and lightweight, but it is difficult to ensure sufficient bending hardness and surface hardness, and conversely if too high, the hardness can be ensured, Thermal insulation sound absorption and light weight are reduced. When used as a cushioning material in applications requiring high heat-absorbing sound absorption and shock absorption, it is preferable to adjust the density as low as possible within the above range. When the density decreases, the fibers become entangled and become close to a general non-woven fiber structure in which the fibers are fused at the intersections. On the other hand, when the density is increased, the fibers are fused in a bundle, and the porous molded body. It becomes a structure close to.

The basis weight of the buffer material can be selected from the range of, for example, about 50 to 10000 g / m ² , preferably 150 to 8000 g / m ² , more preferably about 300 to 6000 g / m ² . In applications where hardness is required and a basis weight, for example, 1000~10000g / m ^2, preferably 1500~8000g / m ^2, more preferably about 2000~6000g / m ^2. If the basis weight is too small, it is difficult to ensure the hardness. If the basis weight is too large, the web is too thick and high-temperature steam cannot sufficiently enter the inside of the web in wet heat processing, and the structure is uniform in the thickness direction. It becomes difficult to make a body.

  When the cushioning material of the present invention is in the form of a plate or a sheet, the thickness is not particularly limited, but can be selected from the range of about 1 to 500 mm, for example, 2 to 300 mm, preferably 3 to 100 mm, more preferably It is about 5-50 mm. If the thickness is too thin, it will be difficult to ensure the hardness, and if it is too thick, the mass will become heavy, and the handleability will deteriorate.

Since the cushioning material of the present invention has a non-woven fiber structure, it has high air permeability. Specifically, the air permeability according to the fragile method is 0.1 cm ³ / (cm ² · sec) or more [eg, 0.1 to 300 cm ³ / (cm ² · sec)], preferably 0.5 to 250 cm ³ / (Cm ² · sec) [for example, 1 to 250 cm ³ / (cm ² · sec)], more preferably about 5 to ²⁰⁰ cm ³ / (cm ² · sec), and usually 1 to 100 cm ³ / (cm ²・ Second). 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 molded body, making it difficult for natural air to enter and exit. On the other hand, if the air permeability is too high, the air permeability increases, but the fiber voids in the molded body become too large and the bending stress decreases.

The buffer material of the present invention exhibits sound absorption in a frequency range (about 10 to 20000 Hz) that can be detected as sound, and is usually used for sound having a frequency of about 100 to 10000 Hz. In particular, the cushioning material of the present invention is effective for sound having a frequency of 200 to 5000 Hz, preferably 300 to 3000 Hz, more preferably 500 to 2500 Hz (especially 500 to 1800 Hz), for example. Specifically, the buffer material having a density of 0.15 g / cm ³ and a thickness of 10 mm may have a normal incident sound absorption coefficient of 0.25 or more (for example, 0.25 to 0.9) with respect to 2000 Hz sound, Preferably it is 0.3-0.8, More preferably, it is about 0.4-0.6. Furthermore, the normal incident sound absorption coefficient for sound of 3000 Hz may be 0.5 or more (for example, 0.5 to 0.99), preferably 0.6 to 0.95, more preferably 0.7 to 0. .9 or so.

  Since the cushioning material of the present invention has a non-woven fiber structure, the heat insulating property is also high, and the thermal conductivity is as low as 0.1 W / (m · K) or less, for example, 0.02 to 0.1 W / (M · K), preferably 0.03 to 0.08 W / (m · K) (particularly 0.04 to 0.07 W / (m · K)).

[Method of manufacturing cushioning material]
In the manufacturing method of the shock absorbing material of this invention, the fiber containing the said wet heat adhesiveness fiber is first made into a web. As a method for forming the web, a conventional method, for example, a direct method such as a spunbond method or a meltblowing method, a card method using meltblown fibers or staple fibers, a dry method such as an airlay 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. Of these webs, a semi-random web and a parallel web are preferred when the proportion of bundled fused fibers is increased.

  Next, the obtained fiber web is sent to the next step by a belt conveyor, and then exposed to superheated or high-temperature steam (high-pressure steam) flow to obtain a shaped body having a non-woven 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 wet-heat adhesive fibers are fused by the sprayed high-temperature steam, and the fiber Each other (wet heat adhesive fibers or wet heat adhesive fibers and other fibers) are three-dimensionally bonded. In particular, since the fiber web in the present invention has air permeability, high-temperature water vapor penetrates into the inside, and a molded body having a substantially uniform fusion state can be obtained. In addition, when a latent crimpable composite fiber is contained, crimp is expressed substantially uniformly in the thickness direction.

  The belt conveyor to be used is not particularly limited as long as it can be subjected to high-temperature steam treatment while basically compressing the fiber web used for processing to a desired density, and an endless conveyor is preferably used. In addition, it may be a general single belt conveyor, or may be transported by combining two belt conveyors as necessary and sandwiching the web between both belts. By carrying in this way, when processing a fiber web, it can suppress that the form of the fiber web conveyed by external forces, such as water used for processing, high temperature steam, and vibration of a conveyor, changes. 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, when it is desired to obtain a molded body 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 hydroentanglement process or the needle punch process, the fibers in the fiber web that is the object to be processed enter the inside of the fiber web without largely moving. . It is considered that due to the invasion action and wet heat action of the water vapor flow into the fiber web, the water vapor flow efficiently covers the surface of each fiber existing in the fiber web in a wet heat state, and uniform heat bonding becomes possible. In addition, since this treatment is performed in a very short time under a high-speed air flow, the heat conduction of the water vapor to the fiber surface is sufficient, but the treatment is completed before the heat conduction to the inside of the fiber is sufficiently achieved. For this reason, the entire fiber web to be processed is not easily crushed or deformed so as to lose its thickness due to the pressure or heat of high-temperature steam. As a result, the wet heat bonding is completed so that the degree of bonding in the surface and the thickness direction is substantially uniform without causing large deformation in the fiber web. Moreover, since heat can be sufficiently transmitted to the inside of the nonwoven structure as compared with the dry heat treatment, the degree of fusion in the surface and thickness direction becomes substantially uniform.

Furthermore, when obtaining a molded body having a high surface hardness and bending strength, when the high-temperature steam is supplied to the web for processing, the web to be processed is placed between a conveyor belt or rollers with a desired apparent density (for example, , About 0.3 to 1 g / cm ³ ), and exposure to high temperature water vapor is important. In particular, when trying to obtain a relatively high-density molded body, it is necessary to compress the fiber web with sufficient pressure when processing with high-temperature steam. Furthermore, it is also possible to adjust to a target thickness and density by securing an appropriate clearance between rollers or between conveyors. In the case of a conveyor, since it is difficult to compress the web at a stretch, 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. Furthermore, it is processed into a molded article having desired sound absorption, bending hardness, surface hardness, lightness, and air permeability by adjusting the steam pressure and the processing speed.

  At this time, if it is desired to increase the hardness, 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 the steam cannot pass through. Since it reflects here, it adhere | attaches more firmly by the heat retention effect of vapor | steam. 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, the water vapor jetting power is reduced. 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, when the pitch is too large, there is a case where high-temperature water vapor does not sufficiently hit the web, so that the web strength is lowered.

  The high-temperature steam is not particularly limited as long as the target fiber can be fixed, and may be set according to the material and form of the fiber used. The pressure is, for example, 0.1 to 2 MPa, preferably 0.2 to The pressure is about 1.5 MPa, more preferably about 0.3 to 1 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. On the other hand, if the pressure is too weak, it may not be possible to give the web the amount of heat necessary for fiber fusion, or water vapor may not penetrate the web, resulting in fiber fusion spots in the thickness direction. 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 about 80 to 120 ° C, and more preferably about 90 to 110 ° 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, it is also possible to impart designability to a molded body obtained by applying predetermined uneven patterns, characters, pictures, etc. to the conveyor belt and transferring them. Further, a plurality of plate-shaped molded bodies may be stacked to form a stacked body, or a stacked body may be formed by stacking with other materials.

  After the fibers of the fiber web are partially wet-heat bonded in this way, moisture may remain in the resulting molded body having the nonwoven fiber structure, and the web may be dried as necessary. As for drying, it is necessary that the surface of the molded body in contact with the heating body for drying does not lose the fiber form due to the heat of drying so that the fiber form does not disappear, and a conventional method can be used as long as the fiber form can be maintained. . 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.

  Furthermore, as described above, the molded body is obtained by adhering wet heat adhesive fibers with high-temperature steam, but partially (such as bonding between molded bodies obtained by wet heat bonding), other conventional methods, For example, you may adhere | attach by processing methods, such as partial hot-pressure melt | fusion (hot embossing etc.) and mechanical compression (needle punch etc.).

  The wet heat adhesive fibers can also be fused by dipping the fiber web in hot water. However, it is difficult to control the fiber adhesion rate by such a method, and a molded product with high uniformity of the fiber adhesion rate is obtained. Is difficult. The reason for this is that the wet heat adhesiveness differs depending on the position due to the air contained in the fiber web, the influence on the structure caused by this air being pushed out of the fiber web, the wet heat bonded fiber web It can be presumed that the deformation of the fine structure inside the fiber by the take-off roller when taking out from the hot water or the difference in the deformation of the fine structure in the vertical direction due to the weight of the hot water contained in the taken-out fiber web.

  The obtained cushioning material is a desired shape (various shapes such as a cylindrical shape, a quadrangular prism shape, a spherical shape, and an ellipsoidal shape) using a mold or the like in the manufacturing process of the above-described cushioning material (molded body). However, the plate-shaped or sheet-shaped molded body obtained by the above-described method may be secondarily molded. The shape of the cushioning material of the present invention is usually a plate shape (flat plate shape, curved plate shape, bent plate shape, etc.), cylindrical shape, or the like.

  As the secondary molding method, for example, cutting may be used, but from the viewpoint of simplicity, secondary molding is preferably performed by conventional thermoforming. Examples of thermoforming 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, wet heat press forming, etc. Is available. In particular, since the reproducibility of the mold is high and it is possible to follow a complicated shape, pressure molding may be performed using the mold, for example, at a temperature of 100 to 150 ° C. (particularly about 120 to 140 ° C.). , And may be molded at a pressure of 0.05 to 2 MPa (particularly about 0.1 to 1 MPa).

  Since the cushioning material of the present invention has a non-woven fiber structure in which a continuous air passage is formed and is excellent in heat insulation sound absorption and shock absorption, various fields that require these characteristics, such as vehicles such as automobiles, It is used for buildings such as roads, houses, factories, and personal protective equipment such as helmets. Specifically, it can be used as a sound absorbing material, a heat insulating material, a sound absorbing heat insulating material, a shock absorbing material, or a partition material (partition material) that requires one or more of these characteristics. In the present invention, there is no strict distinction as a use in these characteristics. For example, even a sound absorbing material has other characteristics such as heat insulation and shock absorption.

  Specifically, as the sound-absorbing heat insulating material (sound absorbing and / or heat insulating material), typically, for example, a vehicle (for example, a vehicle such as an automobile, an aircraft) or a building [for example, a building on a road (for a highway) Can be used as a partition material or a component of a soundproof wall, factory house or equipment, building, house, etc.].

  Among them, as the sound absorbing heat insulating material of the vehicle, since the cushioning material of the present invention is excellent in light weight in addition to the above characteristics, heat insulating sound absorbing parts in automobiles such as feed insulators, dash outer insulators, undercover insulators, wheel houses, etc. Insulators, dash inner insulators, floor insulators, roof liners, rear par shell insulators, rear quarter insulators, and particularly useful as roof liners (ceiling materials) taking advantage of their light weight.

  As a sound-absorbing heat insulating material for a building, the cushioning material of the present invention is excellent in formability and shape retention in addition to the above characteristics, so that it can be used as an interior or exterior material of a building, for example, a partition material (partition wall), a floor board. Suitable for partition boards, ceiling partition boards, doors, shutters, shutters, etc. In addition, the cushioning material of the present invention can be used as a building member that requires air permeability by taking advantage of its excellent air permeability. Furthermore, the cushioning material of the present invention may be used in combination with other building materials (such as hard board), but since both heat-absorbing sound-absorbing and shock-absorbing properties and mechanical properties and moldability are compatible, Unlike the partition board, it is not necessary to form a complicated structure in order to develop the heat insulating sound absorbing property, and the cushioning material of the present invention alone can be used as a member such as the partition board.

  As a typical example of the shock absorber, it can be used as a body protector that protects the human body from an impact, for example, a shock absorber filled in a helmet or safety shoes, for example, a helmet inner.

  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, “parts” and “%” are based on mass unless otherwise specified.

(1) Melt index (MI) of ethylene-vinyl alcohol copolymer
According to JIS K6760, it measured using the melt indexer on the conditions of 190 degreeC and a 21.2N load.

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

(3) Thickness (mm), apparent density (g / cm ³ )
The thickness was measured according to JIS L1913 “General Short Fiber Nonwoven Fabric Testing Method”, and the apparent density was calculated from this value and the basis weight value.

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

(5) Fiber Adhesion Rate Using a scanning electron microscope (SEM), a photograph was taken with the cross section of the molded body magnified 100 times. The photograph of the cross section in the thickness direction of the photographed molded product is divided into three equal parts in the thickness direction, and the number of fiber cut surfaces (fiber end faces) that can be found in each of the three divided regions (front surface, inside (center), back surface) On the other hand, 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 molded body for microscopic photography, the fibers in contact with each other are separated from each other by the stress of each fiber on the cut surface of the molded body. 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 ratio (minimum value / maximum value) of the minimum value with respect to the maximum value was also calculated | required together.

(6) Bending stress It measured according to A method (three-point bending method) among the methods as described in JIS K7017. At this time, the measurement sample was a 25 mm wide × 80 mm long sample, the distance between fulcrums was 50 mm, and the test speed was 2 mm / min. In the present invention, the maximum stress (peak stress) in this measurement result chart is defined as the maximum bending stress. The bending stress was measured in the MD direction and the CD direction. Here, the MD direction refers to a state in which the measurement sample is collected so that the web flow direction (MD) is parallel to the long side of the measurement sample, while the CD direction refers to the long side of the measurement sample. A state in which a measurement sample is collected so that the web width direction (CD) is parallel.

(7) 1.5 times displacement stress In the measurement of bending stress, the stress when the bending amount (displacement) exceeding the maximum bending stress (peak stress) is exceeded and further bent to 1.5 times the displacement is continued. 1.5 times the displacement stress.

(8) Thermal conductivity The thermal conductivity was measured by the unsteady hot wire method according to JIS R2648 “Test method of thermal conductivity by the hot wire method of refractory heat insulating brick”.

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

(10) Durometer hardness Measured by a durometer hardness test of type E and FO according to JIS K6253. For the type E durometer hardness test, use a durometer (manufactured by TECLOCK, "GS-721N"), and for the type FO durometer hardness test, use a durometer (manufactured by TECLOCK, "GS-744G"). did. In particular, when the sample is soft, accurate measurement is difficult with the E type, so measurement was performed only with the FO type.

(11) Sound absorption rate Using a sound absorption rate measurement system using an acoustic impedance tube (manufactured by Bruel & Care Co., 2 microphone impedance tube 4206 type large measurement tube), the normal sound absorption rate according to JIS A-1405 method. Was measured.

Example 1
As a wet heat adhesive fiber, a 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%) ) "Kuraray", "Sophista", fineness 2.2dtex, fiber length 51mm, core-sheath mass ratio = 50/50, number of crimps 21 / 25mm, crimp rate 13.5%).

Using this core-sheath type composite staple fiber, a card web having a basis weight of about 140 g / m ² was prepared by a card method, and seven sheets of this web were stacked to obtain a card web having a total basis weight of about 1000 g / m ² .

  The card web was transferred to a belt conveyor equipped with a 50 mesh, 500 mm wide stainless steel endless net. 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 conveyor, and steam treatment is performed by ejecting 0.4 MPa high-temperature steam from the device in the thickness direction of the card web (perpendicularly). As a result, a molded body having a non-woven fiber structure was obtained. 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 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 10 mm. The nozzles were arranged on the back side of the conveyor belt so as to be almost in contact with the belt.

  The obtained molded body has a board-like form, has hardness enough to be self-supporting, has a central portion, and the tip is in the gravitational direction even if the surface direction is directed in a direction intersecting with gravity. It never turned. The evaluation results of this buffer material are shown in Table 1. Furthermore, the result of having measured the sound absorption performance of this buffer material is shown in FIG.

Example 2
A cushioning material was produced in the same manner as in Example 1 except that 11 fiber webs were stacked to form a card web having a total basis weight of about 1500 g / m ² . The evaluation results of the obtained cushioning material are shown in Table 1. Furthermore, the result of having measured the sound absorption performance of this buffer material is shown in FIG.

Example 3
A cushioning material was manufactured in the same manner as in Example 1 except that 18 fiber webs were stacked to form a card web having a total basis weight of 2500 g / m ² . The evaluation results of the obtained cushioning material are shown in Table 1. Furthermore, the result of having measured the sound absorption performance of this buffer material is shown in FIG.

Example 4
Side-by-side composed of polyethylene terephthalate resin (component A) having an intrinsic viscosity of 0.65 and a modified polyethylene terephthalate resin (component B) copolymerized with 20 mol% isophthalic acid and 5 mol% diethylene glycol as latent crimpable fibers Type composite staple fiber (manufactured by Kuraray Co., Ltd., “PN-780”, 1.7 dtex × 51 mm length, mechanical crimp number 12 pieces / 25 mm, 130 ° C. × 62 minutes after heat treatment for 1 minute, 62 pieces / 25 mm) The core-sheath type composite staple fiber (manufactured by Kuraray Co., Ltd., “Sophista”) and the side-by-side type composite staple fiber (latently crimpable conjugate fiber) in a mass ratio, wet heat adhesive fiber / latent fold A cushioning material was produced in the same manner as in Example 1 in which a card web was produced by blending the compressible conjugate fiber at a ratio of 70/30. The evaluation results of the obtained cushioning material are shown in Table 1. The cushioning material was so soft that accurate measurement could not be performed with a type E durometer.

Comparative Example 1
Table 1 shows the results of evaluation of a commercially available sound absorbing material (manufactured by 3M, “Synthrate”). This sound absorbing material could not be measured with a durometer. Furthermore, the result of having measured the sound absorption performance of this sound absorbing material is shown in FIG.

Comparative Example 2
Table 1 shows the results of evaluation of a commercially available foam board (“Pef” manufactured by Toray Industries, Inc.). The hardness could not be measured with a type E durometer. Furthermore, the result of having measured the sound absorption performance of this foam board is shown in FIG.

Comparative Example 3
Table 1 shows the results of evaluation of commercially available glass fibers (glass wool). The hardness could not be measured with a type E durometer. Furthermore, the result of having measured the sound absorption performance of this glass fiber is shown in FIG.

Comparative Example 4
Table 1 shows the results of evaluation of commercially available polystyrene foam. This polystyrene foam was broken when bent to a displacement of 1.5 times the maximum bending stress. Furthermore, the result of having measured the sound absorption performance of this polystyrene foam is shown in FIG.

  As is clear from the results of Table 1 and FIG. 1, the cushioning material of the example is excellent in sound absorbing and heat insulating properties. In particular, the buffer materials of Examples 1 to 3 have high bending stress and high hardness. On the other hand, the cushioning material of the comparative example has a small hardness and a low moldability. Furthermore, the shock absorbing materials of Comparative Examples 2 and 4 have low sound absorption.

FIG. 1 is a graph showing the sound absorption performance of the cushioning material obtained in the example. FIG. 2 is a graph showing the sound absorption performance of the buffer material of the comparative example.

Claims (9)

A buffer material comprising a wet heat adhesive fiber and having a non-woven fiber structure, wherein the buffer material is composed of a molded body in which fibers are fixed by fusion of the wet heat adhesive fiber,
Obtained by a method comprising a step of forming a fiber containing wet heat adhesive fibers into a web and a step of heat-treating the produced fiber web with high-temperature steam to fuse the fibers to obtain a molded article having a non-woven fiber structure. ,
In the cross section in the thickness direction, the fiber adhesion rate in each region divided into three equal parts in the thickness direction is 75% or less, and the ratio of the minimum value to the maximum value of the fiber adhesion rate in each region is 50% or more. Cushioning material. In addition to having an apparent density of 0.05 to 0.7 g / cm ³ , the maximum bending stress in at least one direction is 0.05 MPa or more, and the bending amount is 1.5 times the bending amount indicating the maximum bending stress. The buffer material according to claim 1, wherein the bending stress is 1/5 or more of the maximum bending stress.   The buffer material according to claim 1, wherein the thermal conductivity is 0.03 to 0.1 W / (m · K). The cushioning material according to any one of claims 1 to 3, which has an air permeability of 0.1 to 300 cm ³ / (cm ² · sec) by a fragile method.   Furthermore, it contains non-humid heat adhesive fibers, and the ratio (mass ratio) of the wet heat adhesive fibers and the non-wet heat adhesive fibers is wet heat adhesive fiber / non-humid heat adhesive fiber = 60/40 to 100/0. Item 5. The cushioning material according to any one of Items 1 to 4.   The buffer material according to any one of claims 1 to 5, wherein the wet heat adhesive fiber contains an ethylene-vinyl alcohol copolymer.   The non-wet heat adhesive fiber is a composite fiber in which a phase structure is formed of a plurality of resins having different heat shrinkage rates, and the composite fiber is crimped substantially uniformly with an average curvature radius of 20 to 200 µm. 6. The cushioning material according to 6.   The shock-absorbing material according to any one of claims 1 to 7, which is a sound-absorbing heat insulating material, an impact absorbing material, or a partition material.   The method comprising the steps of forming a fiber containing a wet heat adhesive fiber into a web, and a step of heat-treating the produced fiber web with high-temperature steam to fuse the fibers to obtain a molded body having a non-woven fiber structure. The method for producing a cushioning material according to any one of 8.

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