JP7184537B2 - fiber structure - Google Patents

Description

The present invention relates to a fiber structure, and furthermore, it consists of a dry nonwoven fabric suitable for automobile interior dry nonwoven fabric, residential dry nonwoven fabric, highway dry nonwoven fabric, electrical product nonwoven fabric, compressor nonwoven fabric, clothing batting, bedding batting, etc. It relates to a fibrous structure.

Conventionally, nonwoven fabrics, which are excellent in sound absorption, sound insulation, and heat insulation, have been widely used as structures for vehicles, houses, highways, electric appliances, compressors, and the like.

For example, felt obtained by impregnating a wood board or regenerated fiber with a thermosetting binder such as phenol resin, nonwoven fabric obtained by impregnating inorganic fiber such as glass fiber with a thermoplastic resin and hot or cold pressing (for example, Patent Document 1), A fiber aggregate composed of a high-melting thermoplastic fiber and a low-melting thermoplastic fiber, in which a part of the low-melting thermoplastic fiber is heat-sealed (for example, Patent Document 2), a non-elastic crimped short fiber and a thermoadhesive composite sound-absorbing fiber structure (for example, Patent Document 3), which is composed of short fibers, fixed points are formed by heat-sealing the heat-adhesive composite short fibers, and the fibers are arranged in the thickness direction (for example, Patent Document 3), and a sheet on the fiber structure A laminate (for example, Patent Literature 4) in which various objects are bonded together has been proposed.

On the other hand, it is also known to use fine fiber to improve sound absorption and heat insulation, and for example, a nonwoven fabric made of meltblown fiber, which is a fine fiber, has been proposed (for example, Patent Document 5). . However, since the fibers are very fine, the thickness is easily deformed by external pressure, and the ultrafine fibers are easily melted during thermoforming, it has been difficult to obtain a nonwoven fabric with a three-dimensional structure of high performance. In addition, although a fiber aggregate using fine fineness fibers obtained by a method other than melt blowing has been proposed (Patent Document 6), when fine fineness fibers are used, uniform dispersion of fibers and generation of neps have been proposed. It was difficult to prevent and it was difficult to obtain a high quality fibrous structure.

Japanese Patent Application Laid-Open No. 59-227442 JP-A-7-3599 Japanese Patent Application Laid-Open No. 2001-207366 JP-A-2004-209975 JP-A-6-212546 JP-A-7-219556

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and an object thereof is to provide a fibrous structure that has good sound absorbing properties and that can easily obtain a complicated shape.

The fiber structure of the present invention is a fiber structure containing ultrafine short fibers having a fineness of 0.02 to 0.6 dtex and thermal adhesive short fibers having a fineness of 1 dtex or more, wherein the fine short fibers have a silicon content of 10 ~ 74 ppm, the number of crimps is 10/25.4 mm (1 inch) or more, the melting point of the heat-adhesive staple fiber is 40 ° C. or more lower than the melting point of the ultrafine staple fiber, and the blending amount of the ultrafine staple fiber is 10 90% by weight, 5-50% by weight of heat-adhesive staple fibers, and an average density of the fiber structure of 0.1 g/cm ³ or less.

Further, the resin constituting the ultrafine short fibers is polyester resin or polyolefin resin, the polyester resin is polyalkylene terephthalate resin or polyalkylene naphthalate resin, the polyolefin resin is polyethylene resin or polypropylene resin. is preferred.
In addition, the number of crimps of the ultrafine short fibers is in the range of 12/25.4 mm to 36/25.4 mm, and the silicon in the ultrafine short fibers is dimethylpolysiloxane, amino-modified polysiloxane, hydroxy-modified polysiloxane, poly oxyethylene-copolymerized polydimethylsiloxane, and the melting point of the ultrafine short fibers is preferably 200° C. or higher.

ADVANTAGE OF THE INVENTION According to this invention, the fiber structure which is easy to obtain a complicated shape while having a favorable sound absorption characteristic is provided.

The fiber structure of the present invention is a fiber structure containing ultrafine short fibers with a fineness of 0.02 to 0.6 dtex and heat-adhesive short fibers with a fineness of 1 dtex or more. The ultrafine short fibers have a silicon content of 10 to 74 pm and the number of crimps is 10/25.4 mm (1 inch) or more, and the thermoadhesive short fibers have a melting point lower than the melting point of the ultrafine short fibers by 40°C or more. have. Further, the fiber structure contains 10 to 90% by weight of ultrafine short fibers, 5 to 50% by weight of heat-adhesive short fibers, and has an average density of 0.1 g/cm ³ or less. .

Normally, when the fiber diameter of the short fibers is small and the number of crimps is large, the entanglement becomes large and non-uniformity becomes remarkable. Although it contains ultrafine staple fibers of several 10/25.4 mm (1 inch) or more, by satisfying other requirements, it has excellent workability even though the fiber diameter is small and the number of crimps is large. is uniformly dispersed, and the uniformity of the finally obtained fiber structure is also excellent.

It is preferable that the ultrafine short fibers and heat-adhesive short fibers used in the fiber structure of the present invention are generally made of a synthetic resin.

Among synthetic fibers, it is preferable to use a resin containing a polyester resin or a polyolefin resin, which are excellent in versatility, as the resin constituting the ultrafine fibers used in the fiber structure of the present invention.

In the present invention, such a polyester resin or polyolefin resin can be used alone, but it is also preferable to use a fiber containing only a part of the polyester resin or polyolefin resin. Alternatively, it is also preferable that the ultrafine short fibers used in the present invention are composite fibers composed of several kinds of resins, one of which is mainly composed of a polyester resin or a polyolefin resin.

Specific examples of polyester resins preferably used in the present invention include polyalkylene terephthalates such as polyethylene terephthalate, polytrimethylene terephthalate, or polybutylene terephthalate (polytetramethylene terephthalate), Alternatively, polyesters of aromatic dicarboxylic acids such as polyethylene naphthalate, polytrimethylene naphthalate, or polyalkylene naphthalates such as polybutylene naphthalate (polytetramethylene naphthalate) and aliphatic diols can be exemplified. Alternatively, it is a polyester obtained from an alicyclic dicarboxylic acid such as polyalkylenecyclohexanedicarboxylate and an aliphatic diol, or a polyester obtained from an aromatic dicarboxylic acid such as polycyclohexanedimethylene terephthalate and an alicyclic diol, polyethylene. Polyesters obtained from aliphatic dicarboxylic acids and aliphatic diols such as succinate, polybutylene succinate, or polyethylene adipate, or polyesters obtained from polyhydroxycarboxylic acids such as polylactic acid and polyhydroxybenzoic acid can also be exemplified. can. Alternatively, a copolymer or a blend of these polyester components in an arbitrary ratio is also preferably exemplified as the resin that becomes the polyester fiber.

Depending on the purpose, the dicarboxylic acid component constituting the polyester may be isophthalic acid, phthalic acid, an alkali metal salt of 5-sulfoisophthalic acid, a quaternary ammonium salt of 5-sulfoisophthalic acid, or a quaternary 5-sulfoisophthalic acid. Phosphonium salts, succinic acid, adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, α,β-(4-carboxyphenoxy)ethane, 4,4-dicarboxyphenyl, 2,6-naphthalenedicarboxylic acid, 2,7 -Naphthalenedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid or 1,4-cyclohexanedicarboxylic acid or a diester compound composed of an organic group having 1 to 10 carbon atoms may be copolymerized as one component or two or more components. . Similarly, diethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, and 1,4-cyclohexanediol are used as diol components constituting the polyester. One component or two components such as methanol, 2,2-bis(p-β-hydroxyethylphenyl)propane, polyethylene glycol, poly(1,2-propylene)glycol, poly(trimethylene)glycol or poly(tetramethylene)glycol You may carry out copolymerization above. Furthermore, ω-hydroxyalkylcarboxylic acid, pentaerythritol, trimethylolpropane, trimellitic acid, or hydroxycarboxylic acid such as trimesic acid, or a compound having 3 or more carboxylic acid components or hydroxyl groups, may be used as one component or two or more components. It is also preferred that the polyester is copolymerized and branched. It is also possible to use a mixture of polyesters having different compositions as exemplified above.

Among them, polyalkylene terephthalate resin or polyalkylene naphthalate resin is preferable as the polyester-based resin preferably used in the present invention in view of its physical properties and ease of handling.

The intrinsic viscosity of the fibers constituting the short fibers of the present invention is preferably 0.35 to 0.50. 50 is particularly preferred. If the intrinsic viscosity is too low, the strength of the fiber tends to be low and fiberization tends to be difficult. On the other hand, if the intrinsic viscosity is too high, the performance of the ultrafine short fibers for dry-laid nonwoven fabric tends to be lowered due to, for example, a decrease in extensibility.

In addition, as the resin other than the above polyester-based resin preferably used in the present invention, it is preferable to use a polyolefin-based resin. More specifically, polyolefins used in the present invention include isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, high density polyethylene, medium density polyethylene, linear low density polyethylene, low density polyethylene, ethylene Propylene random copolymer polyolefin, or polyethylene or polypropylene obtained by block copolymerization or graft copolymerization of the third component is preferred.

The various thermoplastic resins listed above may contain known additives such as pigments, dyes, matting agents, antifouling agents, antibacterial agents, deodorants, fluorescent brighteners, antioxidants, and anti-oxidants. A preferred embodiment is a polyester composition containing a retardant, a stabilizer, an ultraviolet absorber, a lubricant, or the like. For example, it is particularly preferable to contain titanium dioxide or the like as a pigment.

Furthermore, in the present invention, the ultrafine fibers for dry-laid nonwoven fabric are preferably ultrafine fibers of either polyester-based resin or polyolefin-based resin, particularly polyethylene terephthalate-based resin, copolymerized polyethylene terephthalate-based resin, polypropylene-based resin, high density It is preferably one or more resins selected from polyethylene resins.

The ultrafine short fibers used in the present invention are made of fibers composed of the above synthetic resins, and are required to be ultrafine fibers having a fineness of 0.02 to 0.6 dtex. However, when the single yarn fineness is less than 0.01 dtex, the entanglement of the ultrafine fibers becomes significant, and when the single yarn fineness is small, there are many difficulties in terms of spinning technology. More specifically, it becomes difficult to stably produce good quality fibers due to breakage and fluffing occurring in the spinning process. Furthermore, the manufacturing cost tends to increase. Conversely, if the single filament fineness is too large, the properties of the ultrafine fibers tend not to be reflected in the physical properties of the resulting nonwoven fabric. In particular, nonwoven fabrics in the low basis weight range tend to be difficult to obtain strength and denseness between fibers when made into dry nonwoven fabrics.

As for the fineness of such ultrafine short fibers, it is necessary that the single yarn fineness is in the range of 0.02 to 0.6 dtex. The finer the single yarn fineness, the better the ventilation resistance and sound absorption of the fiber structure. However, the finer the fiber structure, the lower the actual rigidity of the fiber itself, and accordingly the sound absorption coefficient around 1000 Hz is improved. . In order to reliably exhibit the effect, it is preferable that the ultrafine short fibers are uniformly spread. On the other hand, if the single yarn fineness is less than 0.01 dtex, the entanglement of the ultrafine fibers becomes significant, and if the single yarn fineness is small, it is difficult in terms of spinning technology. More specifically, it is not preferable because it not only makes it difficult to stably produce fibers of good quality due to the occurrence of breakage and fluff in the spinning process, but also increases the production cost. On the other hand, if the single filament fineness exceeds 1 dtex, it is not possible to ensure the strength and denseness of a nonwoven fabric or the like in a low basis weight region that can bring out the characteristics of ultrafine fibers.

The fiber length of the ultrafine fibers is preferably in the range of 3 to 100 mm, more preferably 4 to 50 mm, even more preferably 5 to 40 mm. If the fiber length is too small, the aspect ratio represented by the fiber length/width of the cross section of the fiber or diameter of the ellipse becomes too small, which affects the bonding between the fibers constituting the nonwoven fabric, the workability of the nonwoven fabric, and the strength of the nonwoven fabric. is not preferable from the viewpoint of On the other hand, if the fiber length is too long, defects tend to occur due to the entanglement of the fibers.

The ultrafine short fibers used in the present invention must be crimped fibers, and the number of crimps must be 10/25.4 mm (inch) or more. It is more preferably 10 to 30/25.4 mm, particularly preferably 15 to 25/25.4 mm. If the number of crimps is less than 10 per 25.4 mm (inch), the carding process cannot be stably passed. On the other hand, if the number of crimps is too large, even if the other requirements of the present invention are satisfied, the entanglement of the fibers tends to become strong, resulting in defects such as neps.

The ultrafine short fibers used in the present invention should have a silicon content of 10 to 74 ppm. Such silicon may be kneaded into the resin that constitutes the fiber, but is more preferably arranged on the surface of the fiber. If the silicon content is less than 10 ppm, defects due to fiber opening property and single filament breakage increase . In particular, the effect of silicon is more pronounced when other inorganic substances are contained in the ultrafine fibers, and is effective when, for example, the pigment titanium dioxide is contained.

In order to contain silicon in this way, it is preferable to add it as a silicon-containing compound. More specifically, dimethylpolysiloxane, amino-modified polysiloxane, hydroxy-modified polysiloxane, polyoxyethylene-copolymerized dimethylpolysiloxane, etc. are exemplified, and at least one type is preferably included. The silicon-containing compound is preferably used particularly when placed on the surface of the fiber. There is no particular problem even if it is mixed with other components having the function of As other components, the oil agent preferably contains an alkyl phosphate metal salt, particularly preferably an alkyl phosphate metal salt having 8 to 18 carbon atoms such as a lauryl phosphate metal salt.

Further, the silicon-containing compound is preferably one that undergoes a cross-linking reaction from the viewpoint of durability against falling off of the silicon component from the fiber. Such a silicon-containing compound is attached to the fiber as a solution and then dried to treat the fiber, and then contained in the ultrafine short fiber of the present invention.

When added as a compound, if the silicon content is too low, defects such as fiber opening property and single filament breakage increase. On the other hand, if the silicon content is too high, the excess component will become scum, which will drop off and stain during the nonwoven fabric processing process, resulting in deterioration of the process condition.

Further, the fiber structure of the present invention must contain thermally adhesive short fibers with a fineness of 1 dtex or more in addition to the ultrafine staple fibers with a fineness of 0.02 to 0.6 dtex as described above.

Such short heat-bondable fibers are preferably synthetic fibers, and more preferably heat-bondable conjugate short fibers. In order to ensure the strength and bulkiness of the fiber structure of the present invention, it is essential to bond the fibers together. It is preferably a conjugate fiber consisting of. In particular, it is preferable that the adhesive component is the sheath component, and the core-sheath composite fiber is composed of another component usually composed of a resin as the core. Moreover, the heat-fusible component of the heat-adhesive short fibers must have a melting point lower than that of the polymer component constituting the ultrafine short fibers by 40° C. or more. If this temperature is less than 40° C., the adhesion is insufficient and the fiber structure becomes stiff and difficult to handle, failing to achieve the object of the present invention.

It is necessary that the fineness of the heat-adhesive short fibers is 1 dtex or more. In this case, the needle passage resistance becomes extremely large, causing needle breakage, fiber breakage, etc., and the desired fiber structure cannot be obtained.

Here, examples of the polymer used as the heat-sealing component of the heat-adhesive short fibers used in the fiber structure of the present invention include polyurethane-based elastomers, polyester-based elastomers, inelastic polyester-based polymers and their copolymers, Examples include polyolefin polymers and copolymers thereof, polyvinyl alcohol polymers and the like.

Among the above heat-sealable components, copolymerized polyester polymers are particularly preferred. For example, the copolymerized polyester is preferably copolymerized polyethylene terephthalate obtained by copolymerizing isophthalic acid as a dicarboxylic acid component. Various stabilizers, ultraviolet absorbers, thickening/branching agents, delustering agents, coloring agents, and various other improving agents may be blended in the above-mentioned polymer, if necessary.

Further, when the heat-adhesive short fibers are conjugate fibers, it is preferable that the partner component of the heat-sealable component is a non-elastic polyester resin component, and the polyester resin component is the above-mentioned ultrafine short fiber. It is possible to utilize resin components similar to those used in the fiber. At that time, the heat-sealing component preferably occupies 1/2 or more of the surface area. Further, the weight ratio of the heat-sealing component and the other components is preferably in the range of 30/70 to 70/30. When the heat-adhesive staple fibers are conjugate staple fibers, the form is not particularly limited, but the heat-fusible component and other components are preferably side-by-side or core-sheath type, and particularly preferably core-sheath type. It is to be. In such a core-sheath type heat-adhesive conjugate staple fiber, another component such as a non-elastic polyester serves as the core portion, and the thermoplastic elastomer serves as the sheath portion. At this time, the core portions of the heat-adhesive short fibers may be concentric or eccentric.

Further, the heat-adhesive staple fibers preferably contain 10 to 5000 ppm of silicon, which further improves the blendability.

The single fiber diameter of the heat-adhesive short fibers used in the fiber structure of the present invention is preferably in the range of 5 to 50 μm. Moreover, the fiber length is preferably longer than that of the ultrafine fibers. As a specific numerical value, short fibers that are cut to a length of 3 to 100 mm are preferred. Further, the range of 4 to 76 mm is preferable, and the range of 5 to 64 mm is particularly preferable.

In the present invention, ultrafine staple fibers having a fineness of 0.02 to 0.6 dtex and thermally adhesive staple fibers having a fineness of 1 dtex or more are blended and heat-treated to cross the thermally adhesive staple fibers. A fibrous structure is formed in which fixed points heat-sealed in a state and fixed points heat-sealed in a state in which the heat-adhesive short fibers and the ultrafine short fibers are intersected.

At this time, it is necessary that the content of ultrafine short fibers with a fineness of 0.02 to 0.6 dtex is in the range of 10 to 90% by weight. More preferably, it is used in a range of 20 to 90% by weight in order to improve sound absorption performance and heat insulation performance. In the fiber structure of the present invention, it is possible to improve the sound absorption performance and heat insulation performance by increasing the ratio of the ultrafine short fibers. Also, the content of the heat-adhesive short fibers should be in the range of 5 to 50% by weight. If the amount of heat-bonded fibers is less than this range, the number of fixation points will be extremely small, making handling difficult and the fiber structure lacking stiffness and poor moldability. On the other hand, if the proportion of the thermally-bonded composite short fibers is more than this range, the number of bonding points becomes too large, resulting in reduced thickness due to heat shrinkage in the heat treatment step, resulting in a decrease in sound absorption.

Furthermore, in the fiber structure of the present invention, it is more preferable that the ultrafine short fibers are polyester short fibers. In particular, when the fiber structure of the present invention is used for sound absorbing parts of a car, etc., it is advantageous when joining it to other board-like structures such as a structure using polyester fiber and a structure using glass fiber that constitute the car. Become. When an olefin ultrafine fiber-based sound absorbing material is used, it is inferior in heat resistance to a polyester-based sound absorbing material, making it difficult to mold together with a board-like structure. Therefore, an adhesive resin or the like was used to join the board-like structure in a separate process, but the use of the adhesive resin and the process were sometimes complicated. When the ultrafine short fibers are polyester short fibers, this step can be omitted, and furthermore, the heat resistance is high, and the product can be integrally molded.

It is also preferable to add colored fibers to the fiber structure of the present invention in addition to the above ultrafine short fibers and thermoadhesive short fibers. In addition to the advantage that stains are less noticeable, it is also preferable for quality maintenance because the state of blended cotton can be easily judged from the appearance. In particular, it is preferable to use a fiber structure in which recoiled fibers are mixed as the colored fibers. Reclaimed fiber is used to collect and reuse used clothing, etc., and contributes to reducing the burden on the environment.

The average density of such a fibrous structure of the present invention must be less than 0.1 g/cm ³ . Further, it is preferably in the range of 0.005 to 0.100 g/cm ³ . More preferably, it is 0.010 g/cm ³ to 0.08 g/cm ³ . If the average density exceeds 0.1 g/cm ³ , the fibrous structure becomes plate-like and subsequent molding becomes difficult. In addition, sound is likely to be reflected, which may make it impossible to use the material as a sound absorbing material. Conversely, if the density is too low, the bonding inside the fiber structure is weak, and handling tends to be difficult.

Moreover, in the fiber structure of the present invention, it is preferable that the bulkiness does not change significantly at 200° C. or higher. For example, it is preferred that the fibrous structure containing ultrafine short fibers changes in bulk by less than 30%, preferably less than 20% at 200°C. In order to obtain such a fiber structure, it is necessary to select a resin having a high melting point of the ultrafine fibers constituting the fiber structure and a high melting point of the components other than the heat-adhesive short fibers of the heat-adhesive short fibers. preferable.
The fiber structure of the present invention is often integrally molded together with other fiber structures. , and the thickness does not decrease, it is possible to continue to secure the original sound absorption at a high level.

Furthermore, it is also preferable that the fiber structure of the present invention has another layer attached to one or both sides thereof. When used as multiple layers in this way, a dry nonwoven fabric containing a large amount of ultrafine fibers can be used for the surface layer, and a dry nonwoven fabric containing a small amount of ultrafine fibers can be used for the back layer. Alternatively, it is also preferable to use a dry nonwoven fabric containing ultrafine fibers for the surface layer and a dry nonwoven fabric containing no ultrafine fibers for the back layer by means of heat bonding, adhesive, needle punching, or the like.

It is also preferable to attach various layers other than the fiber structure of the present invention to the fiber structure of the present invention. For example, it is preferable to bond a nonwoven fabric by a direct spinning method such as spunbond, meltblown or flashbond.

Furthermore, the fiber structure of the present invention is preferably subjected to known functional processing such as water-repellent processing, flameproof processing, flame-retardant processing, and negative ion generation processing. However, it is also one of the preferable aspects to make the part high density.

In order to obtain such a fibrous structure of the present invention, it is preferable to first form a fibrous web. Among them, a web manufacturing method using an air lay method is preferable. For example, more specifically, it is a method in which two or more types of fibers are weighed and uniformly mixed by a mixing facility, and then the fibers are opened. In this case, it is preferable to use a fiber opening machine to spread the fibers and at the same time to mix the fibers uniformly. However, when a high-density metallic wire or the like is used, the cotton sinks into the wire, neps, etc. occur, resulting in deterioration in quality and productivity.

Next, the mixed and spread constituent fibers are aligned by an air stream, and brought into a cylindrical shape by the air stream against the peripheral surface of a suction drum having a mesh surface to be bundled to form a fiber web. At this time, the base material-constituting fibers are sucked in a form in which the fibers are obliquely laminated on the peripheral surface of the suction drum where the constituent fibers are taken up. After that, by conveying the bundled fiber group by a conveyor equipped with a belt and rollers, the surface layer and the back layer are parallel to the belt, but the fibers in the intermediate layer are oriented obliquely in the thickness direction. It is possible to obtain a fibrous web which is packed in a state.

Examples of web forming apparatuses using the air-lay method suitable for such a web forming process include "V12/R" manufactured by AUTEFA, and "RANDO-WEBBER" manufactured by RANDO. ” (registered trademark of the company).

Moreover, in order to obtain the fiber structure of the present invention, it is necessary to perform a heat bonding step in the step of joining the fibers. In this heat-bonding process, the short fibers are heated at a temperature corresponding to the thermal properties of the short fibers under no pressure or while being sandwiched between air-permeable belts. The fiber structure is obtained by heating the fiber and bonding the heat-adhesive staple fiber to other constituent fibers.

Alternatively, after the mixed cotton is sufficiently opened, a web is created by a carding method using metallic wires for ultrafine fibers, the webs are superimposed with a cross layer, and heat treatment is applied to create a fiber structure. . It is also preferable to heat-treat the web while folding it like an accordion (for example, "Struto equipment" manufactured by Struto may be used). Furthermore, it is also possible to perform needle punching in order to suppress surface fluff before heat treatment.

Further, by forming each constituent fiber in the fiber structure of the present invention more three-dimensionally, a fiber structure (dry-laid nonwoven fabric) more suitable for objects having complicated shapes can be obtained. In particular, since cars and the like have complicated shapes, sound leaks through gaps and the like, but by using a dry-type nonwoven fabric that matches the shape, the characteristics of a dry-type nonwoven fabric can be fully exhibited. Although the method for three-dimensional molding is not particularly limited, it can be easily produced by preheating the fiber structure to about 180° C., inserting the heated fiber structure into a mold at room temperature, and pressing. .

Examples are given below in order to make the structure and effect of the present invention concrete, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by weight", and each physical property value in Examples and Comparative Examples was measured according to the following methods.

(1) Silicon content The sample ultrafine fiber for dry nonwoven fabric was molded into a tablet shape, and the front and back surfaces of the tablet were measured twice with a fluorescent X-ray measurement device (ZSX) manufactured by RIGAKU, and the average value was calculated. .

(2) Single yarn fineness Measured by the method described in Japanese Industrial Standard JIS L 1015:2005 8.5.1 A method. That is, a small amount of the fiber sample is drawn parallel with a metal comb and placed on a piece of rag paper placed on a cutting table. A gauge plate is crimped while the fiber sample is stretched straight with an appropriate force, and cut to a length of 30 mm with a blade such as a safety razor. 300 fibers are counted as one set, and the mass is weighed to determine the apparent fineness. From this apparent fineness and the separately measured equilibrium moisture content, the net fineness is calculated by the following formula. An average value of 5 times of regular fineness was calculated.
F=[(100+R0)/(100+Rc)]×D
F: Regular fineness D: Apparent fineness R0: Official moisture content (%) (value specified in Japanese Industrial Standard JIS L 0105 4.1)
Rc: equilibrium moisture content (%)

(3) Fiber length Measured by the method described in Japanese Industrial Standard JIS L 1015:2005 8.4.1 A method.

(4) Number of crimps Measured by the method described in Japanese Industrial Standards JIS L 1015:2005 8.12.1.

(5) Intrinsic viscosity: [η]
0.12 g of a fiber (polyester polymer) sample was dissolved in 10 mL of a tetrachloroethane/phenol mixed solvent (volume ratio 1/1), and the intrinsic viscosity (dL/g) at 35°C was measured.

(6) Melt flow rate: MFR
The melt flow rate was measured according to Japanese Industrial Standard JIS K 7210 Condition 4 (measurement temperature: 190°C, load: 21.18N). The melt flow rate is a value measured using polymer pellets immediately before melt spinning as a sample.

(7) Melting point Using a thermal differential analyzer type, measurement was performed at a temperature increase of 20°C/min to obtain a melting peak. When the melting temperature is not clearly observed, a micro melting point measuring device is used, and the temperature (softening point) at which the polymer begins to soften and flow is taken as the melting point. In addition, the average value was calculated|required by n number 5.

(8) Card passability of fibers Black polyester fibers in which carbon particles with a round cross section of 2.2 dtex are kneaded into white ultrafine fibers are laminated in two layers at a weight ratio of 70% and 30%, respectively. did. After that, the cotton is passed through a pin-cylinder type fiber opening machine twice, and then a fiber web is produced using a high-speed card tester manufactured by Ikegami Kikai Co., Ltd. The occurrence of neps and the blended cotton of the obtained fiber web Based on the situation, evaluation was made according to the following criteria. Since the black polyester fiber was used, the nonwoven fabric had a gray color as a dry-laid nonwoven fabric, and the stain was hardly visible and could withstand practical use.
A: The fibers easily pass through the carding machine, there are no unopened fibers, and neps are hardly generated.
B: There seems to be no unopened fibers, but some neps are generated.
C: A web in which a large amount of neps are generated or unopened fibers remain.

(9) Thickness (mm) of fiber structure and sheet-like material
Measured according to JIS K6400.

(10) Density of fiber structure (g/cm ³ )
Density (g/cm3) was determined by the following formula.
Density (g/cm ³ ) = web basis weight (g/cm ² )/fiber structure thickness (cm)

(11) Sound absorption characteristics (sound absorption coefficient)
The sample is placed so that the sheet-like material is positioned on the sound source side, and the sound absorption coefficient is the normal incident sound absorption coefficient according to JIS-A1405, and is a multi-channel analysis system 3550 type manufactured by Bruel & Kjar (software: BZ5087 type 2-channel analysis software). was measured by the two-microphone method. The sound absorption coefficients were compared at 1000 Hz.

(12) Formability The material was hot-drawn at 190°C for 180 seconds to form a case having an inner diameter of 60 mm, a height of 20 mm and a thickness of 5 mm. The appearance of the body of this case was observed and evaluated according to the following criteria.
Grade 3: A beautiful case was created.
Grade 2: The case was able to be made, although there were some wrinkles.
Grade 1: The case cannot be made or there is a problem with the product.

[Reference example 1]
Polyethylene terephthalate (PET) chips containing 0.3% by weight of titanium dioxide and having an intrinsic viscosity of 0.47 dL/g are melted at 290°C and discharged from a spinneret having 2504 round holes at a discharge rate of 340 g/min. Then, it was taken off at a speed of 500 m/min to obtain an undrawn polyethylene terephthalate yarn having a single filament fineness of 2.7 dtex. The undrawn yarns were pulled together to form a tow of 163,000 dtex and drawn in warm water at a total draw ratio of 32.8. Thereafter, a polyoxyethylene-copolymerized polydimethylsiloxane-based oil was applied as a component containing lauryl phosphate salt as a main component and containing silicon. Thereafter, crimping was applied in a push-type crimper box to obtain ultrafine short fibers for dry nonwoven fabric having a single filament fineness of 0.06 dtex, a fiber length of 24 mm, and a number of crimps of 17/25.4 mm.

On the other hand, as a heat bonding fiber, a core-sheath type polyester fiber (sheath component: low melting point PET [melting point 110 ° C.], core component: polyethylene terephthalate [melting point 256 ° C.]) has a fiber diameter of 2.2 dtex and a fiber length of 51 mm. A thermoadhesive short fiber having a crimp number of 9/25.4 mm was prepared.

50% by weight of ultrafine polyester fiber and 20% by weight of thermoadhesive short fiber are combined with 30% by weight of separately prepared black polyester fiber (fiber diameter: 2.2 dtex, fiber length: 51 mm, number of crimps: 10/25.4 mm). After blending, it was thoroughly mixed in a mixing device and passed through a pin cylinder and a metallic wire cylinder to further improve blendability and openability. After that, a dry nonwoven fabric was prepared by an air laying method, and then heat-adhered in a hot air circulating furnace with net-shaped belts on the top and bottom and the temperature of the hot air was set to 180 ° C., resulting in a basis weight of 306 g / m ² and a thickness of 21 mm. , and a fiber structure (dry nonwoven fabric) having a density of 0.015 g/cm ³ was obtained. Table 1 shows the fiber properties, moldability of the fiber structure (dry nonwoven fabric), and sound absorption properties. Other preparation conditions and physical properties are also shown in Table 1.

[Example 1]
A fiber structure (dry nonwoven fabric) was obtained in the same manner as in Reference Example 1, except that the ultrafine staple fibers had a single filament fineness of 0.10 dtex, a cut length of 32 mm, and a number of crimps of 14/25.4 mm. rice field. The results are also shown in Table 1.

[Reference example 2]
A fiber structure was obtained in the same manner as in Reference Example 1, except that the amount of dimethylpolysiloxane attached to the ultrafine short fibers was increased by 10 times. The results are also shown in Table 1.

[Reference example 3]
Ultrafine short fibers, heat-adhesive short fibers, and black fibers are the same as in Reference Example 1, and the mixing ratio is changed to 25% by mass of ultrafine short fibers, 20% by mass of heat-adhesive short fibers, and black After blending with 55% by weight of polyester fiber, a fiber structure having a basis weight of 487 g/m ² , a thickness of 11.0 mm and a density of 0.05 g/cm ³ was obtained in the same manner as in Reference Example 1. Table 1 shows the fiber properties, the formability of the fiber structure, and the sound absorption properties. Other preparation conditions and physical properties are also shown in Table 1.

[Reference Example 4]
70 parts of polyethylene phthalate (PET) and 30 parts of polypropylene (PP) are melt-mixed with N2 gas as a foaming agent, extruded from an extruder at an extrusion temperature of 170 to 350° C., and rapidly cooled at the die outlet to be taken off. A reticulated atypical fiber sheet was obtained. On the other hand, a large number of polyester tow sheets of about 450,000 denier were combined, laminated with an acrylic binder, overfed twice and stretched at a stretching ratio of 10, and heat-pressed to obtain a sheet with a basis weight of 70 g/m ² .

This sheet is inserted in front of the hot air circulating furnace in Reference Example 1 and bonded with the web of Reference Example 3 in a hot air circulating furnace in which the temperature of the hot air is set to 180° C. and which has net-like belts on the upper and lower sides. Thus, a fiber structure (dry nonwoven fabric) having a basis weight of 562 g/m ² , a thickness of 11.7 mm and a density of 0.048 g/cm ³ was obtained. Table 2 shows the fiber characteristics, moldability of the fiber structure (dry nonwoven fabric), and sound absorption properties. Table 2 shows the results.

[Comparative Example 1]
Ultrafine short fibers were obtained in the same manner as in Reference Example 1, except that the amount of dimethylpolysiloxane attached to the fibers in the drawing step was reduced. The amount of silicon contained in the fibers was 6 ppm. A fiber structure was obtained in the same manner as in Reference Example 1 except for the above. Numerous neps were confirmed on the surface of the fabricated fiber structure. The results are also shown in Table 2.

[Comparative Example 2]
A fibrous structure was obtained in the same manner as in Reference Example 1, except that the number of crimps applied to the ultrafine short fibers was adjusted to 8 by adjusting the number of crimps imparted by the push-type crimper box. After that, in the same manner as in Reference Example 1, the mixed cotton was mixed and opened to form a web using a metallic card using a wire for ultra-thin fibers, and the webs were superimposed with a cross layer. The manufacturing conditions are also shown in Table 2. However, many ultrafine fibers fell under the metallic card, and many web cuts occurred when the web was transferred from the metallic card equipment to the cross layer equipment. .

[Comparative Example 3]
TC3403 (basis weight = 318 g/m ² , thickness = 30 mm) manufactured by Three M Co., Ltd. under the trade name of Thinsulate was prepared. This product is composed of polyester thick fibers and PP meltblown fibers, and when the fiber diameter was measured by an electron microscope, the diameter of the PP meltblown fibers was distributed from 0.5 to 15 μm, and the average value of 100 fibers was It was 3.3 μm. When this thinsulate fiber was heat-molded in the same manner as in Reference Example 1, the ultrafine fibers contained therein were fused and a fiber structure with high sound absorption was not obtained. Table 2 shows the sound absorption coefficient of Thinsulate before heat molding.

Claims (7)

A fibrous structure containing ultrafine short fibers with a fineness of 0.02 to 0.6 dtex and heat-adhesive short fibers with a fineness of 1 dtex or more, wherein the ultrafine short fibers have a silicon content of 10 to 74 ppm and the number of crimps is 10. / 25.4 mm (1 inch) or more, the heat-bondable staple fiber has a melting point lower than the melting point of the ultrafine staple fiber by 40 ° C or more, and the blending amount of the ultrafine staple fiber is 10 to 90% by weight. 1. A fiber structure characterized by containing 5 to 50% by weight of elastic short fibers and having an average density of 0.1 g/cm ³ or less. 2. The fiber structure according to claim 1, wherein the resin constituting the ultrafine staple fibers is polyester resin or polyolefin resin. 3. The fiber structure according to claim 2, wherein the polyester resin is a polyalkylene terephthalate resin or a polyalkylene naphthalate resin. 3. The fiber structure according to claim 2, wherein the polyolefin resin is polyethylene resin or polypropylene resin. The fiber structure according to any one of claims 1 to 4, wherein the number of crimps of the ultrafine short fibers is in the range of 12/25.4 mm to 36/25.4 mm. Any one of claims 1 to 5, wherein the silicon in the ultrafine short fibers is derived from at least one of dimethylpolysiloxane, amino-modified polysiloxane, hydroxy-modified polysiloxane, and polyoxyethylene-copolymerized polydimethylsiloxane. A fiber structure according to any one of claims 1 to 3. The fiber structure according to any one of claims 1 to 6, wherein the ultrafine short fibers have a melting point of 200°C or higher.