JPH11200221A - Nonwoven fabric structure with improved shock absorbing performance - Google Patents

Abstract

(57) [Problem] To provide a nonwoven fabric structure which has cushioning property, shock absorbing property and vibration absorbing property, and is excellent in moldability and recyclability. SOLUTION: The following requirements (a) to (d) are satisfied;
The thickness in which the elastic single fibers are randomly arranged is 0.5 to
50 mm, a nonwoven fabric having a bulk density of 0.15 to 0.50 g / cm ³ , further having at least one tan δ peak between −20 and 50 ° C. as an elastic polymer constituting the elastic single fiber, And the one whose value is 0.4 or more is used. (A) the average diameter of the elastic single fibers is in the range of 0.1 to 50 μm; (b) 2 to 50 single fibers are fused in parallel with each other.
Bonded and have a length of 10 times the average diameter of the single fiber
500 to 3000 linear fusion parts in the range of 1000 times
It is (c) cross section perpendicular to the fiber axis of the linear fused part, parallel shape, dog-legged shape, a rectangular shape or a bundle; to have pieces / cm ^2;
And (d) 1000 to 5000 pieces / cm ^{3 of} point fusion parts formed by fusing the intersections of the linear fusion parts and the intersections of the linear fusion parts and the single fibers, respectively. To have.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric made of a thermoplastic elastomer-based elastic yarn and having a shock-absorbing performance. More specifically, the present invention is not only excellent in shock absorbing and vibration absorbing performance, but also has high cushioning property and air permeability, and is excellent in moldability and recyclability. The present invention relates to a nonwoven fabric structure that can be suitably used for surfaces, shoes, and the like.

[0002]

2. Description of the Related Art Conventionally, foamed polyurethane, nonwoven fabric in which fiber aggregates are entangled, or a bonding treatment is performed with a binder or heat-fused fibers have been used as a structure having a cushioning property. However, urethane foam has poor air permeability and moisture permeability, so it is easy to humid, and it has a problem that it is difficult to recycle.While entangled or bonded nonwoven fabric has air permeability, the matrix fiber is an inelastic fiber. In the case of, the bulkiness is likely to decrease,
In addition, there is a problem that plastic deformation under heating is large. In order to solve the above problem, for example, Japanese Patent Application Laid-Open No. 7-238
Japanese Patent No. 459 proposes a laminated net having excellent durability and cushioning property by fusing a 100 to 100,000 denier fiber aggregate made of an elastic resin as a constituent matrix to give a three-dimensional structure. ing.

[0003] However, this material is excellent in air permeability and cushioning property, but even when an elastic material having vibration absorbing performance is used for the matrix fiber, the resilience is high due to the high thickness of the single fiber constituting the net-like material, and the resilience is high. The force is large and cannot be applied to applications intended to absorb vibration and shock. Here, as a material having a shock or vibration absorbing performance, a polymer or a gel having a high loss coefficient has been used directly. However, as a result of putting too much emphasis only on shock and vibration absorption, these materials were poor in cushioning property and air permeability, heavy, and inferior in handleability.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to achieve a nonwoven fabric structure which cannot be achieved by the above-mentioned conventional products, has a cushioning property, a shock absorbing property and a vibration absorbing property, and is excellent in moldability and recyclability. Is to provide the body.

[0005]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have made intensive studies on the relationship between the shock-absorbing property and the compression elasticity and the nonwoven fabric structure, and as a result, have found that a specific thermoplastic elastomer can be used. It has been clarified that the viscoelastic properties possessed by the polymer can be sufficiently exhibited by including the specific fiber diameter (fine fiber diameter) and a special structural portion in the nonwoven fabric.

[0006] Thus, according to the present invention, the following (a) to
The thickness in which elastic single fibers are randomly arranged to satisfy the requirement of (d) is 0.5 to 50 mm, and the bulk density is 0.15.
Is a nonwoven fabric having a tan δ peak of −20 to 50 g / cm ^3.
Provided is a nonwoven fabric structure having an impact buffering property, wherein the nonwoven fabric structure has at least one between ° C and 0.4 or more.

(A) The average diameter of the elastic single fiber is 0.1 to
(B) two to fifty of the single fibers are fused in parallel with each other;
Bonded and have a length of 10 times the average diameter of the single fiber
500 to 3000 linear fusion parts in the range of 1000 times
It then is cross-sectional shape perpendicular relative to (c) the fiber axis of the linear fused part, parallel shape, dog-legged shape, a rectangular shape or a bundle; it has pieces / cm ^2;
And (d) 1000-5000 / cm ³ point fusion parts each formed by fusing the intersections between the linear fusion parts and the intersections between the linear fusion parts and the single fibers. To have. The nonwoven fabric structure of the present invention basically comprises the above (a) to (d)
It is necessary to satisfy the following requirements. Hereinafter, these points will be described.

The average diameter (requirement a) of the elastic fibers constituting the nonwoven fabric structure of the present invention must be in the range of 0.1 to 50 μm, preferably 2 to 20 μm. Accordingly, the internal structure of the nonwoven fabric can be kept uniform, external stress can be received without being locally concentrated, and repulsion can be suppressed. In other words, if the fineness is less than 0.1 μm, it is difficult to obtain a uniform fineness between single fibers, while if it exceeds 50 μm, unevenness in the internal structure occurs in the nonwoven fabric, and sufficient impact buffering performance cannot be exhibited. In addition, since the rigidity of the fiber increases, the repulsive force also increases. In addition, the diameter mentioned here means that the cross section of the elastic single fiber is irregular (for example, elliptical,
In the case of a polygon or the like, it means a diameter when they are regarded as a circular cross section of a corresponding thickness (denier).

Next, the linear fused portion (requirement b) means that 2 to 50 elastic single fibers are fused and bonded in a parallel state, and the length is 10 times the average diameter of the single fibers. It refers to a site that is in the range of １０００1000 times.

Since the stretchable nonwoven fabric of the present invention includes the linear fused portion, it is possible to secure voids in the thickness direction between the fiber layers while having a small diameter. Creates sex. When the number of the linear fusion parts is less than 500 per unit area of 1 cm ^{2 of the} nonwoven fabric, the above effect is difficult to be obtained. On the other hand, when the number exceeds 3,000, the fiber diameter as a whole becomes large and the resilience becomes high. This is not preferred because The preferred range is 100
0 to 2500 pieces.

On the other hand, if the number of single fibers constituting the linear fused portion exceeds 50, the apparent fiber diameter becomes too large. Usually, the number is preferably 5 to 20. As for the fusion / bonding form, if the cross-sectional shape perpendicular to the fiber axis is parallel, U-shaped, rectangular or bundled (requirement of C),
The bulkiness of the nonwoven fabric can be maintained, and uniform and appropriate voids can be secured. Further, if the length of the linear fused portion is less than 10 times the average diameter of the single fiber, it is difficult to obtain the effect of linear fusion, and if it exceeds 1000 times, it causes non-uniformity. . A preferred range is 50-500 times.

On the other hand, the point fusion part (requirement of d) is defined as a crossing point between the linear fusion parts or a crossing point between the linear fusion part and the single fiber where both are fused. Point. This point-like fused portion is 1 cm ² per unit area of the nonwoven fabric.
When 000 to 5,000 are present, the bonding between the nonwoven fabric layers and between the layers is strengthened, and the external stress is evenly dispersed.
When the number is less than 1,000, the strength and elasticity of the nonwoven fabric are not sufficient. On the other hand, when the number exceeds 5,000, the nonwoven fabric loses softness and resilience becomes excessively high. The preferred range is 1
It is 500-4000 pieces.

The next important factors are the thickness and bulk density of the nonwoven fabric and the characteristics of the elastic polymer used as the raw material of the constituent single fibers. Hereinafter, these points will be described. The thickness of the nonwoven fabric structure of the present invention is required to be 0.5 to 50 mm in order to exhibit impact buffering performance against external stress and to secure air permeability, though it depends on the application. The thickness is 0.
If it is less than 5 mm, sufficient shock-absorbing impact performance as a structure is not exhibited, and if it exceeds 50 μm, the effect is saturated. The preferred range of this thickness is 1 to 20 mm.

Further, the bulk density of the nonwoven fabric structure is 0.1
If it is less than 5 g / cm ^3, it will be difficult to exhibit the shock-absorbing performance of the nonwoven fabric, while if it exceeds 0.50 / cm ³ , the nonwoven fabric will be hard and the resilience will increase. A preferred range is from 0.20 to 0.35 g / cm ³ .

The elastic single fiber constituting the nonwoven fabric structure of the present invention is made of an elastic polymer having at least one tan δ peak between −20 and 50 ° C. and having a value of 0.4 or more. It is necessary to become. That is, the bulky and dense voids promote cushioning, and the polymer having the above-mentioned viscoelastic properties promotes shock absorbing properties.

Here, the tan δ value is obtained by setting the frequency to 10 Hz.
And is measured with respect to temperature. tan
Those having a δ peak value of less than −20 ° C. or exceeding 50 ° C. cannot exhibit sufficient shock buffering performance in a practical use temperature range. The same applies to the case where the peak value is less than 0.4. Preferably, the peak value is 0.
6 or more and appear at around 0 to 30 ° C. The number of peaks may be one or more, and the peak may be broader with respect to temperature.

As long as the elastic polymer satisfies the above viscoelastic properties, polyurethane, polyester elastomer,
Any kind of olefin elastomer may be used, but polyester elastomers are preferred in consideration of heat stability during fiber formation, light resistance after fabric formation, yellowing resistance, and the like.

The polyester-based elastomer must be made of a block copolymer elastic material containing the following polyesters A and B as constituents. (A) an acid component in which 50 mol% or more is terephthalic acid based on the total acid component;
A polyester comprising a diol component in which at least mol% is 1,4-butanediol (crystalline hard segment component). (B) 50 to 100 mol% as the total acid component has 8 to 8 carbon atoms.
A polyester (soft segment component) comprising an acid component which is an aromatic dicarboxylic acid of 16 and a diol component which is an aliphatic diol compound having 3 to 20 carbon atoms in an amount of 50 to 100 mol% based on all diol components.

In the polyester A constituting the crystalline hard segment, at least 50 mol%, preferably at least 70 mol% of the acid component is terephthalic acid or an ester-forming derivative thereof, and at least 50 mol% of the diol component, preferably at least 70 mol%. A polybutylene terephthalate-based polyester obtained by polycondensing a component unit in which at least mol% is 1,4-butanediol or an ester-forming derivative thereof is preferably used. That is, the hard segment is a crystalline aromatic polyester segment, and other dicarboxylic acids include isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 4,4 '-Diphenyldicarboxylic acid, adipic acid and the like, while the diols include ethylene glycol, trimethylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexane Dimethanol and the like can be mentioned. The acid component and the diol component may be used alone or in combination. However, the crystalline polyester A alone constituting the hard segment has an intrinsic viscosity of 0.6 to 2.0 and a melting point of 120 ° C. Preferably at 150 ° C. or higher,
It is preferably 0 ° C. or lower, more preferably 220 ° C. or lower. If the intrinsic viscosity is less than 0.6, the melt-moldability of the obtained copolymerized polyester will be significantly reduced, and the performance as a nonwoven fabric structure will also be poor. Conversely, if the intrinsic viscosity exceeds 2.0, the melt-kneading temperature must be set high during the production of the copolymerized polyester, which is not preferable from the viewpoint of thermal degradation of the polyester.

On the other hand, as the polyester B constituting the soft segment, 50 to 100 mol% of the total acid component is composed of an acid component comprising an aromatic dicarboxylic acid having 8 to 16 carbon atoms, and 50 to 100 mol% of the total % Is carbon number 3
And a diol component which is an aliphatic diol compound of No. 20 to 20.

The aromatic dicarboxylic acid component reduces the crystallinity in order to function as a soft segment in the obtained block copolymerized polyester without lowering the hydrolysis resistance and heat resistance of the soft segment polyester. It must occupy the above amounts for purposes.
Preferred examples of the aromatic dicarboxylic acid component include, but are not limited to, terephthalic acid, isophthalic acid, and diphenyldicarboxylic acid.

The acid component other than the aromatic dicarboxylic acid component includes an aliphatic dicarboxylic acid component having 4 to 20 carbon atoms. When the number of carbon atoms of the aliphatic dicarboxylic acid component is less than 4, the number of carbon atoms existing between carboxyl groups is small, so that the obtained block copolymerized polyester is susceptible to hydrolysis and has poor thermal stability during melt spinning. . Conversely, if the number of carbon atoms exceeds 20, the aliphatic dicarboxylic acid is not preferable because it has problems such as high cost and difficulty in obtaining it. The preferred carbon number is 7-20. Aliphatic dicarboxylic acids that can be preferably used include, for example, azelaic acid, sebacic acid, decanedicarboxylic acid and the like. These may be used alone or in combination of two or more.

On the other hand, as the aliphatic diol compound,
Alkylene glycol is mentioned, but if the carbon number of the diol is less than 3, the number of repeating structural units per unit weight increases, and the hydrolysis resistance is inferior. Conversely, if the number of carbons exceeds 20, the reactivity is undesirably low. On the other hand, when the content of the aliphatic diol component is less than 50 mol%, the glass transition temperature of the block copolymer polyester increases, but the flexibility of the copolymer polyester decreases.

Such diol compounds include propylene glycol, tetramethylene glycol, 1,5
-Pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, triethylene glycol, trimethylpentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 1,
Examples thereof include 9-nonanediol and eicosanediol, but those having an alkyl group in a side chain are particularly preferable in order to reduce the crystallinity of the soft segment. These diol compounds can be used alone or
More than one species may be used in combination.

The intrinsic viscosity of the polyester B alone constituting the soft segment is preferably in the range of 0.6 to 1.0. If the intrinsic viscosity is less than 0.6, the melt-moldability of the obtained block copolymerized polyester is significantly reduced, and the performance as a nonwoven fabric structure is also poor. Conversely, if the intrinsic viscosity exceeds 1.0, the melt-kneading temperature must be set high during the production of the block copolymerized polyester, which is not preferable from the viewpoint of thermal degradation of the polyester.

In order to obtain the above-mentioned polyester ester type block copolymer elastomer, the polyester A constituting the hard segment and the polyester B constituting the soft segment may be melt-kneaded and subjected to a blocking reaction. It is preferable that each copolymerization ratio in the blocking reaction is (polyester A) :( polyester B) = (10-70) :( 90-30) by weight ratio. When the copolymerization ratio of the polyester A constituting the hard segment is less than 10% by weight, the hard segment portion in the obtained block copolymerized polyester is too small, and the heat resistance, the moldability, the workability at the time of producing the nonwoven fabric, and the like are reduced. Not only does it decrease, but the elongation stress of the nonwoven fabric structure becomes insufficient. Conversely, if it exceeds 90% by weight, the elongation elastic recovery of the block copolymerized polyester becomes insufficient. The blocking reaction may be a batch system, a continuous system, or any system.For example, each polyester component may be individually subjected to a polycondensation reaction to a desired intrinsic viscosity, and then mixed to perform a blocking reaction. Good.

Of course, the elastic polymer may contain a flame retardant and, if desired, additives such as a chain extender, a filler, an antioxidant and a lubricant.

Further, in the nonwoven fabric structure of the present invention, the elastic single fibers on the surface of the nonwoven fabric are heat-fused at least at one contact point with each other by heat fusion to form a smooth portion. It preferably occupies 10% or more of the surface of the nonwoven fabric structure.

By fusing the single fibers on the surface layer to form a smooth portion, the surface of the nonwoven fabric becomes fluffed and deformed when the nonwoven fabric is installed and constructed, or when subjected to shock or vibration. And stress can be efficiently transmitted to the inside. This smooth portion can be easily formed by thermocompression bonding the surface of the nonwoven fabric using an emboss or flat calender.

If the area occupancy of the smooth portion is less than 10%, sufficient shape retention cannot be exhibited. In order to secure the air permeability, it is preferably 20 to 60%.

Next, a method for producing the nonwoven fabric structure of the present invention will be described. The nonwoven fabric structure of the present invention can be prepared by a method such as a spunbond method or a melt blow method (for example,
-95362, JP-B-63-31581,
Japanese Patent Publication No. Hei 4-47578).
As a method for easily obtaining a small-diameter elastic fiber having the above-mentioned characteristics (a) to (d), a melt blow method is most desirable.

In the melt blow method, a molten polymer is discharged from a spinneret having a large number of spinning holes arranged in the width direction.
A method in which fibers formed by injecting a high-temperature and high-speed gas flow from a pair of so-called lip portions provided adjacent to a base and a slit formed between the bases and thinning are collected on a sheet. In addition, a single fiber having a small diameter can be easily obtained, and the molten polymer can be deposited while directly forming a sheet. Therefore, the nonwoven fabric of the thermoplastic elastomer can be most preferably obtained. The average fiber diameter of the single fibers constituting the nonwoven fabric can be easily changed in the range of 0.1 to 50 μm by appropriately changing the melt blow conditions according to the purpose and required use.

The preferred melt viscosity of the polymer is from 100 poise to 3000 poise, more preferably 5 poise.
It is not less than 00 poise and not more than 2000 poise. If the melt viscosity is too low, yarn breakage and polymer balls tend to occur,
In addition, the uniformity of the fiber diameter becomes poor. On the other hand, if the melt viscosity is too high, it becomes difficult to reduce the fiber diameter.

The spinning temperature of the polymer is given by the melting point of the polymer +
The temperature is preferably 10 ° C. or higher and 100 ° C. or lower, and it is preferable to lower the viscosity at a temperature as high as possible within a range where the polymer does not thermally decompose and a process condition is stable. If the temperature is too high, the melt viscosity becomes high, and thermal decomposition is likely to occur, so that long-term operation stability decreases. In addition, the discharge amount per single hole cannot be determined unconditionally because it depends on the target fiber diameter and the hole diameter of the spinning hole.
When it is 1 to 10 m / min, a nonwoven fabric satisfying the requirements (a) to (d) is obtained. This range is preferably from 1 to 5 m / min.

The high-temperature and high-pressure gas for drawing and thinning the discharged polymer is preferably air or water vapor. If the temperature of the traction gas is too far from the spinning temperature of the polymer, it affects the temperature of the discharged polymer. Therefore, the spinning temperature of the polymer is not lower than −10 ° C. and the melting point of the polymer is not higher than 100 ° C., more preferably the spinning temperature of the polymer. +10 to 50 ° C.
The gas flow rate is appropriately determined depending on the target fiber diameter, the discharge amount, and the bonding state, and depends on the jet slit width of the gas flow, but the preferable flow rate is 0.01 to 0.2 Nm per 1 cm of die width. ³ / min. 0.01 Nm ³ /
If it is less than minute, thinning does not proceed sufficiently, and the unevenness of the obtained nonwoven fabric becomes large. If it exceeds 0.2 Nm ³ / minute, fiber breakage occurs frequently depending on the width of the slit and the discharge amount.

The single fibers that have been discharged and drawn by a high-temperature, high-pressure gas are deposited as a nonwoven fabric on a collecting surface such as a net having a suction function. The distance between the lower surface of the base and the collecting surface can be appropriately selected depending on the solidification state of the single fiber, the desired density, and the structure.
If the collecting surface is located too low with respect to the solidification temperature of the polymer, not only will the linear fusion zone decrease, but the single fiber flow will be disturbed by the jet gas flow and the accompanying flow, and the single fibers will be bundled. Entangled in the fabric and cause a nonwoven fabric group. Also, if the collecting surface is located too high, the single fiber shrinks due to hot air,
Bulkiness may be lost. Preferred distance is 10-8
0 cm.

The obtained nonwoven fabric structure may be used alone or in a plurality of layers, depending on the intended use.

[0038]

EXAMPLES The present invention will be described more specifically below, but the present invention is not limited thereto. In addition,
In the examples, "parts" indicates parts by weight, and each physical property value was measured by the following method.

(1) Average Single Fiber Diameter (Fiber Diameter) The cross section of the nonwoven fabric was calculated by averaging 100 single fiber diameters from a × 500 electron micrograph and averaging them.

(2) The number of fused single fibers, the length and the number of the linearly fused portions, and the number of dot-like fused portions in the linearly fused portion The surface of the nonwoven fabric was measured from an electron micrograph of × 50 magnification. The number of fused single fibers in the linear fused portion was determined. The length of the linear fused portion was also determined, and the magnification with respect to the average single fiber diameter was calculated. Further, the number m of linear fusion parts and the number of point fusion parts are calculated for the area of 4.8 mm ² and calculated to be the number per 1 cm ² , and are involved in the linear fusion with respect to the total number n of single fibers. As the number of single fibers to be obtained, the ratio of the linearly fused portion was calculated by the following equation. Ratio (%) of linear fusion parts = m / n × 100

(3) 50% Compressive Stress The nonwoven fabric was hollowed out to a diameter of 100 mmφ, laminated to a thickness of 20 mm, and compressed to 50% of the sample thickness at a head speed of 20 mm / min using an Intesco compression stress tester. The stress at the time of performing was measured, and it measured as stress per unit area.

(4) 50% Compressive Elasticity Recovery Rate The nonwoven fabric was cut out to a diameter of 100 mmφ, laminated to a thickness of 20 mm, and subjected to 50% of the sample thickness at a head speed of 20 mm / min using a compression stress tester manufactured by Intesco Corporation. , The head was immediately inverted, and the thickness v 'when the load became zero was measured. The thickness before the load was calculated as v using the following equation. 50% compression elastic recovery (%) = v ′ / v × 100

(5) Compression durability: 12.7 g / cm ² , 127.4
g / cm ² , and allowed to stand at room temperature for 10 days. After removing the weight, the thickness w ′ for 30 minutes was measured.
Was calculated by the following equation. Compression durability (%) = w ′ / w × 100

(6) tan δ A dynamic viscoelasticity measuring device (DDV-25 manufactured by Orientec Co., Ltd.)
FP) was measured at a measurement frequency of 10 Hz for a 0.5 mm thick film of an elastic polymer constituting the nonwoven fabric structure.

(7) Shock Absorbing Performance From 30 cm above a nonwoven polymer having a diameter of 100 mmφ,
An iron ball having a weight of 50 g and a diameter of 20 mmφ was dropped, and was calculated from the rebound height 1 by the following equation. Shock absorption performance (%) = (30-1) / 30 × 100

(8) Air permeability Measured according to JIS L1096.

[Example 1] Dimethyl terephthalate 194
Parts by weight, 162 parts by weight of tetramethylene glycol, and 0.15 parts by weight of titanium tetrabutoxide were charged into a transesterification reactor, and heated at 190 ° C. under a nitrogen gas atmosphere.
The ester exchange reaction was carried out while the generated methanol was allowed to flow out of the system.

After completion of the transesterification, 230
C., polycondensation reaction, intrinsic viscosity 1.07, melting point 223
Thus, a polybutylene terephthalate-based polyester polymer at a temperature of ° C was obtained.

On the other hand, 136% by weight of dimethyl isophthalate, 62% by weight of dimethyl sebacate, and 180 parts by weight of 1,6-hexanediol were added to 0.1% of dibutyltin acetate.
The mixture was heated together with 3 parts by weight to remove by-product methanol from the reaction system. The reaction product is transferred to a reaction vessel capable of
The reaction was carried out at 55 ° C. under reduced pressure to obtain an amorphous polyester having an intrinsic viscosity of 0.80.

The above-mentioned polybutylene terephthalate-based polyester and amorphous polyester were mixed in a weight ratio of 35:65.
After reacting at an internal temperature of 240 ° C. for 50 minutes under a reduced pressure of 1 mmHg, 0.2% of phenylphosphonic acid was used as a catalyst deactivator.
Part by weight was added, and the mixture was further stirred for 10 minutes to completely stop the blocking reaction.

The polyester ester block copolymer obtained has an intrinsic viscosity of 1.15 and a melting point of 205.
° C, the tan δ peak was at -10 to 0 ° C, and its value was 0.7.

The copolymer was dried under reduced pressure of 1 mmHg for 120 minutes.
After drying at 280 ° C. for 16 hours and melting at 280 ° C. by a melt blow method, the discharge hole is 1 mm in the width direction of the die in a circular cross section.
Discharge linear velocity 2.1
The polyester was stretched and thinned by discharging compressed air at a rate of 0.04 Nm ³ / min per 1 cm width of the die after discharging at m / min.
It was collected as a nonwoven fabric on a collecting net provided below.

The average single fiber diameter of the obtained nonwoven fabric is 8 μm, the bulk density of the nonwoven fabric is 0.20 g / cm ³ , the thickness is 9 mm, and the fibers constituting the fabric are 100% along the fiber axis direction.
7 or more fused at a distance of more than a micron
2% was contained, and the number of fused portions at that time was almost 8 to 12, and the cross-sectional shape of the fused portion was almost parallel or bundle. The number of linear fusion parts per unit area of 1 cm ^{2 of the} nonwoven fabric is 2,000, and the number of point fusion parts is 23.
There were 00 pieces.

Further, the obtained non-woven fabric was subjected to an emboss calender with a metal embossing roller on the upper side and a metal flat roller on the lower side, and the upper surface of the non-woven cloth was 75% / surface area at 135 ° C. and a linear pressure of 30 kgf / cm ^2.
Is fused so as to be smooth, and the bulk density is 0.26 g
/ Cm ³ , thickness 7 mm, air permeability 0.2 cc / cm ² /
s was obtained. Table 1 shows the compression characteristics and shock absorbing performance of this nonwoven fabric structure.

Comparative Example 1 A non-woven fabric having a thickness of 9 mm was obtained from the polymer used in Example 1 by a melt blow method. At this time, the discharge linear velocity of the polymer was set to 12.2 m / min, and the compressed air flow rate was set to 0.10 Nm ³ / cm per die width of 1 cm.
The procedure was carried out in the same manner as in Example 1 except that the amount was changed. The average fiber diameter of the obtained nonwoven fabric is 10 μm, the apparent density of the nonwoven fabric is 0.23 g / cm ³ , and the thickness is 7 mm. Of the fibers constituting the fabric, at a distance of 100 μm or more along the fiber axis direction Two or more fused fibers are contained in 85% of the total single fibers, and the number of fused fibers is 3 to
There were many variations of ten. The number of linear fused portions per unit area of 1 cm ^{2 of the} nonwoven fabric was 3,500, and the number of dotted fused portions was 5,400.

Further, the obtained nonwoven fabric was embossed in the same manner as in Example 1 to partially fuse the surface of one side of the nonwoven fabric.
Bulk density 0.38 g / cm ³ , thickness 7 mm, air permeability 0.0
A non-woven fabric of cc / cm ² / s was obtained. Table 1 shows the compression characteristics and shock absorbing performance of this nonwoven fabric structure.

Comparative Example 2 A non-woven fabric having a thickness of 9 mm was obtained from the polymer used in Example 1 by a melt blow method. At this time, the discharge linear velocity of the polymer was 0.48 m / min, and the compressed air flow rate was 0.03 Nm ³ / cm per die width.
The procedure was carried out in the same manner as in Example 1 except that the amount was changed. The average fiber diameter of the obtained nonwoven fabric is 55μ, the apparent density of the nonwoven fabric is 0.16 g / cm ³ , and the thickness is 10 mm. Of the fibers constituting the fabric, at a distance of 600 microns or more along the fiber axis direction. 35% of the total number of single fibers contains two or more fused fibers, and the number of fused fibers is 2 to 4 in most cases and the cross-sectional shape is almost parallel. Met. The number of linear fused portions per unit area of 1 cm ^{2 of the} nonwoven fabric was 450, and the number of dotted fused portions was 100.

Further, the obtained nonwoven fabric was embossed in the same manner as in Example 1 to partially fuse the surface of one side of the nonwoven fabric.
Bulk density 0.22 g / cm ³ , thickness 7 mm, air permeability 2.0
A non-woven fabric of cc / cm ² / s was obtained. Table 1 shows the compression characteristics and shock absorbing performance of this nonwoven fabric structure.

Example 2 Dimethyl Terephthalate 194
Parts by weight, 162 parts by weight of tetramethylene glycol, and 0.15 parts by weight of titanium tetrabutoxide were charged into a transesterification reactor, and charged under a nitrogen atmosphere.
The temperature was raised to ° C., and transesterification was carried out while the produced methanol was allowed to flow out of the system.

After completion of the transesterification, 230
C., polycondensation reaction, intrinsic viscosity 1.07, melting point 223
Thus, a polybutylene terephthalate-based polyester polymer at a temperature of ° C was obtained. On the other hand, 194 parts by weight of dimethyl isophthalate and 150 parts by weight of triethylene glycol were heated together with 0.3 parts by weight of dibutyltin acetate to remove by-product methanol from the reaction system. The reaction product was transferred to a reaction vessel capable of reducing pressure and reacted at 255 ° C. under reduced pressure to obtain an amorphous polyester having an intrinsic viscosity of 0.75.

The above polybutylene terephthalate-based polyester and the amorphous polyester are mixed in a weight ratio of 30:70.
° C, and under a reduced pressure of 1 mmHg at an internal temperature of 24.
After reacting at 0 ° C. for 50 minutes, 0.2 parts by weight of phenylphosphonic acid was added as a catalyst deactivator, and the mixture was further stirred for 10 minutes to completely stop the block reaction.

The polyester ester block copolymer obtained has an intrinsic viscosity of 1.04 and a melting point of 183 ° C.
And the tan δ peak was at 0 to 5 ° C., and its value was 0.7.

The copolymer was dried under reduced pressure of 1 mmHg for 120 minutes.
After drying at 260 ° C. for 16 hours and melting at 260 ° C. by a melt blow method, the compressed air heated at 300 ° C. was discharged using the die of Example 1 at a discharge linear velocity of 2.1 m / min. Flow rate per width 1cm is 0.05Nm
³ / min after stretching and thinning the polyester, 3
It was collected as a nonwoven fabric on a collection net provided 5 cm below.

The average single fiber diameter of the obtained nonwoven fabric was 8 μm, the bulk density of the nonwoven fabric was 0.20 g / cm ³ , the thickness was 9 mm, and the fibers constituting the fabric were 100 μm along the fiber axis direction.
8 or more fused at a distance of more than a micron
0% was contained, and the number of fused parts was 4 to 20 in most cases, and the cross-sectional shape of the fused part was almost parallel or bundled. The number of linear fusion parts per unit area of 1 cm ^{2 of the} nonwoven fabric was 2,500, and the number of point fusion parts was 3,200.

Further, the obtained nonwoven fabric was embossed in the same manner as in Example 1 to partially fuse the surface of one side of the nonwoven fabric.
Bulk density 0.26 g / cm ³ , thickness 8 mm, air permeability 0.2
A non-woven fabric of cc / cm ² / s was obtained. Table 1 shows the compression characteristics and shock absorbing performance of this nonwoven fabric structure.

Comparative Example 3 Dimethyl Terephthalate 167
Parts by weight, 105 parts by weight of tetramethylene glycol, polytetramethylene glycol 32 having a number average molecular weight of 2,000
After the transesterification reaction of 5 parts by weight in the reactor, the internal temperature was raised to 245 ° C., the reaction was carried out under a weak vacuum for 30 minutes, and then the reaction was carried out under a high vacuum for 200 minutes. The melting point of the obtained block copolymer with polyetherester is 190
° C, the intrinsic viscosity is 1.52, the tan δ peak is broad in the range of -60 to -50 ° C, and its value is 0.2
Met.

The copolymer was heated at 115 ° C. under a reduced pressure of 1 mmHg.
For 16 hours and melted at 260 ° C. by a melt blow method, and then, using the die of Example 1, discharging at a linear velocity of 1.7 m / min. 0.06Nm ³ flow rate per 1cm width
The polyester was stretched and thinned at a rate of / min, and then collected as a nonwoven fabric on a collection net provided 35 cm below the die.

The average single fiber diameter of the obtained non-woven fabric is 7 μm, the bulk density of the non-woven fabric is 0.19 g / cm ³ , the thickness is 9 mm, and the fibers constituting the fabric have a linear fused portion length. 55% of the total number of fibers fused at two or more fibers at a distance of 70 microns or more is contained, and the number of fused fibers is 3 to 8
Most of the books had a parallel cross section. The number of linear fusion parts per unit area of 1 cm ^{2 of the} nonwoven fabric was 1,500, and the number of dot fusion parts was 2,300.

Further, the obtained nonwoven fabric was embossed in the same manner as in Example 1 to partially fuse the surface of one side of the nonwoven fabric.
Bulk density 0.27 g / cm ³ , thickness 7 mm, air permeability 0.1
A non-woven fabric of cc / cm ² / s was obtained. Table 1 shows the compression characteristics and shock absorbing performance of this nonwoven fabric structure.

[0070]

[Table 1]

As shown in Table 1, Examples 1 and 2, which are embodiments of the present invention, do not have a strong repulsive force, have excellent recoverability after compression, have good cushioning properties, It was also excellent in buffer properties. On the other hand, in Comparative Example 1, the fineness is small, but the number of linear and dot fusion parts constituting the nonwoven fabric structure is extremely large. Became inferior. In Comparative Example 2 having a large single fiber diameter, both the compressive stress and the compressive recovery rate were low, and the cushioning property was poor. In addition, the set was large and the shock absorbing performance was poor. In Comparative Example 3 in which the polymer composition was out of the range of the present invention, compression recovery and set were good, but rubber elasticity was high and impact cushioning performance was poor.

Although the nonwoven fabric structure of Example 1 was used as an elbow pad, it had extremely excellent impact buffering properties and exhibited a good feeling of use. Further, when the structure was attached to the periphery of the door and used, the impact sound when the door was closed was greatly reduced, and a comfortable environment was obtained. Furthermore, when used as a shoe insole, the shock was appropriately absorbed, and it became possible to walk comfortably for a long time.

[0073]

The nonwoven fabric structure of the present invention has the softness exhibited by the small diameter single fibers, and the fine particles formed by the small diameter single fibers being appropriately linearly or dottedly fused. Since the voids are uniformly dispersed inside, good cushioning properties are exhibited. Further, the single fiber is made of a single component elastic polymer having a specific viscoelastic characteristic, so that the single fiber also has recyclability and shock absorbing performance. Therefore, the obtained nonwoven fabric structure does not cause concentration of stress for building materials, bedding, seating surfaces, shoe soles, and the like, and thus can be suitably used for pressure sores.

Claims (3)

[Claims] (1) satisfying the following requirements (a) to (d):
The thickness in which the elastic single fibers are randomly arranged is 0.5 to
A non-woven fabric having a thickness of 50 mm and a bulk density of 0.15 to 0.50 g / cm ³ , wherein the elastic polymer constituting the elastic single fiber is t
A nonwoven fabric having impact cushioning performance, having at least one an δ peak between −20 and 50 ° C. and having a value of 0.4 or more. (A) the average diameter of the elastic single fibers is in the range of 0.1 to 50 μm; (b) 2 to 50 single fibers are fused in parallel with each other.
Bonded and have a length of 10 times the average diameter of the single fiber
500 to 3000 linear fusion parts in the range of 1000 times
It is (c) cross section perpendicular to the fiber axis of the linear fused part, parallel shape, dog-legged shape, a rectangular shape or a bundle; to have pieces / cm ^2;
And (d) 1000-5000 / cm ³ point fusion parts each formed by fusing the intersections between the linear fusion parts and the intersections between the linear fusion parts and the single fibers. To have. 2. An elastic single fiber comprising the following polyesters A and B:
2. The nonwoven fabric structure having shock-absorbing performance according to claim 1, comprising a block copolymer elastic material containing: (A) A polyester comprising an acid component whose terephthalic acid accounts for at least 50 mol% based on the total acid component and a diol component whose 1,4-butanediol accounts for at least 50 mol% based on the total diol component. (B) 50-100 as total acid component
A polyester comprising an acid component in which mol% is an aromatic dicarboxylic acid having 8 to 16 carbon atoms and a diol component which is an aliphatic diol compound having 3 to 20 carbon atoms in 50 to 100 mol% based on the total diol component. 3. The non-woven fabric surface elastic elastic fibers are thermocompression-bonded to each other at contact points to form a smooth portion, and the entire area of the portion occupies at least 10% of the surface layer of the non-woven fabric structure. 2. A nonwoven fabric structure having the shock absorbing performance according to 1.