JP2001200428A - Polyester-based staple fiber and fiber structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester-based staple fiber capable of giving a fiber structure difficult to be deformed by heat under a high temperature environment such as about 70 deg.C, having a high compression stress and excellent in resistance to setting and provide the fiber structure. SOLUTION: This polyester-based staple fiber comprises a polyester having >=80 deg.C glass transition temperature and >=85% retention rate of crimp before and after the heat treatment at 210 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention can be used for automobile seats, ceiling materials, floor materials, sound absorbing materials or trunk room interior materials by mixing with heat-bondable fibers, heat-treating and heat bonding. The present invention relates to a polyester-based short fiber and a fibrous structure capable of forming a fibrous structure (nonwoven fabric, solid cotton, or the like) that is not easily deformed even in a long-term or high-temperature atmosphere.

[0002]

2. Description of the Related Art Conventionally, furniture stuffing such as sofas and chair backrests, cushions and the like, beds and car seat cushioning materials, or car ceiling materials, flooring materials, sound absorbing materials,
Polyurethane foam has been mainly used for interior materials of trunk rooms and the like. However, polyurethane foam has problems from the standpoint of safety, recyclability, and environmental protection, such as the generation of nitrogen-containing toxic gas during combustion, or the destruction of the ozone layer in the upper atmosphere by Freon gas used during production. Has been pointed out.

[0003] Therefore, as a material replacing the polyurethane foam, a fibrous structure composed of polyester fiber and polyester-based heat-adhesive fiber is disclosed in JP-A-58-31150, JP-A-2-154050, and JP-A-3-22.
No. 0354 has been proposed.

[0004] In general, as a cushion material for an automobile, it is required that the interior of the car in summer is assumed, and that it does not sag even in an atmosphere of about 70 ° C. Since the glass transition temperature (hereinafter abbreviated as Tg) of the fiber is about 70 ° C.,
Poor resilience to compression in an atmosphere of about ℃
It was also very easy to settle.

Further, since the adhesive component of the heat-adhesive fiber for adhering the main fiber is amorphous polyester, the adhesive strength in a high-temperature atmosphere is inferior. This causes the cushioning property to decrease.

To solve these problems, Japanese Patent Laid-Open Publication No. Hei 6-165888 discloses that a polyethylene naphthalate (hereinafter abbreviated as PEN) fiber and an adhesive component have a melting point (hereinafter abbreviated as Tm) of 80. There has been proposed a fibrous structure composed of a thermo-adhesive fiber using a polymer having a crystallinity of not less than ° C.

In this fiber structure, since the main fiber is made of PEN and the Tg is 120 ° C., the repulsive stress against compression is large. The part became strong, and the resulting fiber structure had a somewhat improved set in a high-temperature atmosphere.

[0008] However, the PEN fiber used in this fiber structure tends to have a reduced crimp ratio due to the heat treatment at the time of producing the fiber structure, and the compression stress and the high temperature of about 70 ° C. The sag resistance under the atmosphere was not sufficiently satisfactory.

[0009]

DISCLOSURE OF THE INVENTION The present invention eliminates the sag of such a conventional fiber structure made of polyester-based fiber, and is less likely to be thermally deformed even in a high-temperature atmosphere of about 70 ° C. It is an object of the present invention to provide a polyester-based short fiber and a fiber structure capable of obtaining a fiber structure having high heat resistance and excellent sag resistance.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems and to develop a fiber structure which is hardly thermally deformed, the present inventors have paid close attention to the polymer physical properties and crimping performance of short fibers, and have studied diligently. As a result, the present invention has been achieved. That is, the present invention provides the following (1) and (2). (1) It is made of a polyester having a Tg of 80 ° C. or more, and has a crimp retention ratio of 85 before and after heat treatment at 210 ° C.
% Of polyester-based short fibers. (2) a glass transition temperature of 20 to 80 ° C. and a melting point of 130
It is characterized by comprising 10 to 50% by weight of a polyester-based thermo-adhesive fiber whose fiber surface is covered with a crystalline copolymerized polyester at 180 to 180 ° C, and 90 to 50% by weight of a polyester-based short fiber described in (1). Fiber structure.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polymer used for the polyester short fiber of the present invention must be a polyester having a Tg of 80 ° C. or higher. As a result, the fiber structure containing the polyester staple fiber of the present invention as a constituent fiber is made of the conventional PET Tg.
(About 70 ° C.), the molecular structure is stable under an atmosphere of 70 ° C., the permanent deformation hardly occurs even under a load, and the heat deformation hardly occurs.

When the Tg of the polymer is less than 80 ° C.,
Under the atmosphere of about ℃, the molecular structure becomes unstable due to the micro-Brownian motion of the amorphous part, and the fiber made of this polymer is easily deformed under load, and the resulting fiber structure is also easily deformed by heat. Become.

The polyester polymer having a Tg of 80 ° C. or higher constituting the polyester short fiber of the present invention includes polyethylene-2,6-naphthalate and polyethylene-
2,7-naphthalate, poly-1,4-cyclohexylene dimethylene terephthalate, and the like. If necessary, terephthalic acid, isophthalic acid, cyclohexanedicarboxylic acid, adipic acid, as long as the effects of the present invention are not impaired. Other auxiliary raw materials such as sebacic acid, ethylene oxide adduct of bisphenol S or bisphenol A, cyclohexanedimethanol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol and the like may be copolymerized. And various additives may be included.

However, when these copolymer components are contained, the amorphousness increases as the copolymerization amount increases, and the T
Since m may decrease, heat resistance may deteriorate, and the resulting fiber structure may be thermally deformed, the upper limit of the copolymerization amount is preferably about 30 mol%.

The intrinsic viscosity of these polyester polymers is preferably from 0.40 to 0.64, more preferably from 0.45 to 0.60.

The polyester short fiber of the present invention is mixed with a heat-adhesive fiber and heat-bonded by heat treatment to form a fibrous structure. The heat treatment to be performed at the time of producing the fibrous structure is usually performed by the Tm of the adhesive component of the heat-adhesive fiber.
It is carried out at the above temperature, and at a temperature 50 ° C. higher than the Tm of the adhesive component of the thermoadhesive fiber in the highest case. Therefore,
In the short fiber of the present invention, it is necessary that the retention of the crimp ratio before and after the heat treatment at a temperature of 210 ° C. is 85% or more.

By setting the retention rate of the crimp rate of the polyester-based short fiber to 85% or more, the crimped form becomes a two-dimensional or three-dimensional structure, and the resulting fiber structure has excellent bulkiness and thermal deformation. It is difficult to do.

When the retention rate of the crimp rate of the polyester short fiber before and after the heat treatment at 210 ° C. is less than 85%,
The crimped form is lost after the heat treatment, the fiber becomes linear, and the structure of the obtained fiber structure tends to be one-dimensional, and the bulk is reduced. Further, when the fiber structure is used in a high-temperature atmosphere, the fiber structure is easily deformed by heat.

The number of crimps and the rate of crimp are preferably 5 to 20 crimps / 25 mm, and the crimp rate is preferably 10 to 30%.

Here, the performance of the short fiber of the present invention is 2
85% retention of crimp rate before and after heat treatment at 10 ° C
In order to achieve the above, it is preferable to manufacture by the following method. First, a polyester having a Tg of 80 ° C. or higher was melt-spun and stretched 3.0 to 5.0 times.
A tension heat treatment is performed at ~ 150 ° C, a crimp is applied by a press-in type crimping machine, and then a relaxation heat treatment is applied at 160 ~ 240 ° C. It is not clear why the retention rate of the crimp rate is increased by this method, but the relaxation heat treatment performed after performing the tension heat treatment and applying the crimp is performed at a temperature higher than the tension heat treatment temperature, thereby maintaining the crimped form. It is presumed that crystallization proceeds in a state of being crimped, and a strong crimp is provided.

The steps of drawing, tension heat treatment, crimping and relaxation heat treatment may be performed continuously or in separate steps, and cut into short fibers.

The fineness of the polyester short fibers is not particularly limited and may be determined according to the intended use, but is generally 2 to 40 denier, preferably 4 to 30 denier.

The form of the fiber is not particularly limited as long as the object of the present invention is not impaired. The fiber may be a fiber consisting of polyester alone, or a copolymer of polyester and another component. It may be a side-by-side type.

The cross-sectional shape of the fiber may be a round cross-section, a flat cross-section, a six-leaf, W-shaped, H-shaped, triangular cross-section or other irregular cross-section, or a hollow cross-section. In the case of a hollow cross section, the hollow ratio is preferably set to 5 to 30%.

Next, the fiber structure of the present invention will be described. The fibrous structure of the present invention is composed of the polyester-based thermo-adhesive fiber and the above-mentioned polyester staple fiber of the present invention. The polyester-based thermo-adhesive fiber has a Tg of 20 to 80 ° C and a Tm of 130. The fiber surface is covered with a crystalline copolyester at -180 ° C.

When the copolyester is amorphous, if the ambient temperature exceeds the Tg of the copolyester, the molecular structure becomes unstable, so that the bonded portion does not become strong and the resulting fiber structure Is easy to set when used for a short time or in a high temperature atmosphere, and does not function as a cushion material. Therefore, it is necessary to use a copolyester having crystallinity for the adhesive component.

If the crystalline copolymerized polyester has a Tg of less than 20 ° C., the yarn-forming properties are poor, such as the occurrence of single yarn adhesion during melt spinning.
It is not preferable because it becomes easy to set under an atmosphere of about 70 ° C. On the other hand, if the Tg exceeds 80 ° C., although it is effective for sag resistance of the fibrous structure, it is necessary to perform stretching at a high temperature in the yarn-making process, and the plastic crystallization due to stretching and partial crystallization occur simultaneously. Starts, and the stretchability decreases, such as the occurrence of yarn breakage, which is not preferable.

If the Tm is less than 130 ° C., there is no heat resistance, so that when the fiber structure is used, the fiber structure is easily depressed in a high-temperature atmosphere. On the other hand, when the temperature exceeds 180 ° C., a fusion heat treatment at a high temperature is required, and the polymer is likely to be decomposed by the high temperature heat treatment.

The crystalline copolyester having the above-mentioned physical properties includes, for example, a terephthalic acid component, an aliphatic lactone component, an ethylene glycol component,
It can be obtained by using 1,4 butanediol component.

Here, when an aliphatic lactone component is used, its ratio is preferably set to 10 to 20 mol% of the acid component (total of the terephthalic acid component and the aliphatic lactone component). If the content is less than 10 mol%, the crystallinity is improved, but the Tm exceeds 180 ° C., and it is necessary to perform the thermal bonding treatment at a high temperature. If the content exceeds 20 mol%, adhesion occurs at the time of spinning, and the spinnability deteriorates. As the aliphatic lactone component, a lactone having 4 to 11 carbon atoms is preferable. Among them, ε-caprolactone and δ-valerolactone are preferable.

The crystalline copolyester covering the surface of the polyester-based heat-bondable fiber may be any of isophthalic acid, phthalic acid, adipic acid, sebacic acid, diethylene glycol, triethylene, or the like as long as the effects of the present invention are not impaired. It may contain a copolymer component such as ethylene glycol.

As the form of the polyester-based heat-bondable fiber, as long as the fiber surface is covered with the above-mentioned crystalline copolyester, it may be an all-melt type fiber composed of only the crystalline copolyester, Further, a core-sheath type composite fiber in which polyethylene terephthalate is disposed as a core component and the above-mentioned crystalline copolymerized polyester is disposed as a sheath component may be used.

The fineness of the polyester-based heat-adhesive fiber is not limited, but is 2 to 60 in consideration of the cushioning property.
Denier is appropriate.

Further, the mixing ratio of the polyester staple fiber and the polyester thermoadhesive fiber constituting the fiber structure of the present invention is such that the polyester staple fiber is 90 to 50% by weight,
It is necessary that the content of the polyester-based heat-adhesive fiber is 10 to 50% by weight, and more preferably, the content of the polyester-based short fiber is 80 to 60% by weight, and the content of the polyester-based heat-adhesive fiber is 20 to 40% by weight.

10% by weight of polyester-based heat-adhesive fiber
If it is less than 1, the number of bonding points between the fibers becomes small, so that the fiber structure loses its shape, the compressive residual strain rate increases, and the elastic recovery rate of the fiber structure deteriorates. On the other hand, if the amount of the polyester-based thermoadhesive fiber is more than 50% by weight, the number of bonding points between the fibers increases, but the bulk decreases, and the amount of the polyester-based short fiber decreases. And it is not preferable.

[0036] Specific examples of the fiber structure of the present invention include non-woven fabric and solid cotton. Above all, the solid cotton preferably has a density of 20 to 40 kg / m ³ in consideration of cushioning properties and weight reduction in automotive seat applications.

Further, the fiber structure of the present invention has a density of 2
25% compressive stress at 0 to 40 kg / m ³ is 8 kgf
It is preferable that it is above. 25% compressive stress is 8kgf
If it is less than 30, a feeling of bottom contact occurs, the sitting comfort is poor, and long-term use causes tiredness of the hips and pain in the buttocks, which impairs comfort and makes the fiber structure easily slip off Not preferred.

Further, it is preferable that the compression set at 70 ° C. of the fibrous structure is 20% or less. 20%
If the temperature exceeds 70 ° C., use of the film in an atmosphere of about 70 ° C. causes a large set, which gives a feeling of bottoming out, which is unfavorable because of poor sitting comfort.

Here, the method for producing the fibrous structure of the present invention will be described by way of an example. 90 to 50% by weight of the polyester staple fiber of the present invention and the polyester thermoadhesive fiber 10
Approximately 50% by weight of cotton wool is mixed, and a card machine is used to prepare a web. The heat-bonding component is melted by a heat treatment apparatus in which the web is heated to a temperature not lower than Tm of the heat-bonding component of the polyester-based heat-bondable fiber and not higher than Tm of the heat-bonding component + 50 ° C. The thickness is regulated so as to obtain the density. Once cooled to room temperature, a crystallization heat treatment is performed at a temperature equal to or higher than the crystallization start temperature (hereinafter, abbreviated as Tc) of the thermal bonding component and Tc + 30 ° C. or lower of the thermal bonding component.
The polyester-based heat-adhesive fiber promotes the crystallinity of the bonded portion to obtain a fibrous structure. In this case, needling may be performed before the heat treatment. As the heat treatment apparatus, a hot air dryer, a rotary drum dryer, or the like is used.

[0040]

Next, the present invention will be described specifically with reference to examples. The determination of various physical properties in the examples was performed as follows. (1) Tg and Tm Measurement was performed at a heating rate of 20 ° C./min using a differential scanning calorimeter DSC-7 manufactured by PerkinElmer. (2) Fineness It was measured by the method of JIS L-1015-7-5-1. (3) Crimp ratio Measured according to the method of JIS L-1015-7-12-12. (4) Retention rate of crimp rate After leaving the obtained short fibers in a hot air drier at a temperature of 210 ° C for 20 minutes, the crimp rate after heat treatment was measured by the method of JISL-1015-7-12-12. did. At this time, the crimp rate after the heat treatment and the crimp rate before the heat treatment were determined by the method (3), and the retention rate of the crimp rate was determined using the following equation. Retention of crimp rate (%) = (B / A) × 100 A: Crimp rate before heat treatment (%) B: Crimp rate after heat treatment (%) (5) Residual compressive strain Thickness as test specimen A square fiber structure having a length of 20 mm and a size of 10 cm × 10 cm was prepared and measured by a method of JIS K-6401 (70 ° C. × 22 hours). (6) 25% compressive stress A fibrous structure having a density of 25 kg / m ³ and a thickness of 35 mm was prepared as a test piece, and was subjected to the method of JIS K-6401.
The compression force at the time of 25% compression with respect to the initial bulk was measured.

Example 1 A PEN polymer having a Tg of 120 ° C. and a Tm of 267 ° C. was dried under reduced pressure by a conventional method, and then spun at a spinning temperature of 300 ° C. and a discharge rate of 400 g / min using a melt spinning apparatus.
/ Min to obtain an undrawn fiber. Next, this undrawn fiber was bundled to 100,000 denier, and drawn at 95 ° C.
After stretching in a wet bath at 95 ° C. and a stretching ratio of 4.5 times,
In a heat drum, a tension heat treatment at a temperature of 110 ° C is performed.
The crimp is applied by a press-in type crimp applying machine, and further 170 ° C.
For 5 minutes, cooled to room temperature, and cut into 51 mm pieces to obtain PEN short fibers (main fibers) having a fineness of 15 denier. Next, Tm256 was added to the core component as a heat-adhesive fiber.
The melt-spinning apparatus was used for spinning using PET at 0 ° C. and a crystalline copolyester having Tg of 32 ° C. and Tm of 160 ° C. as the sheath component. The fiber was drawn at a spinning temperature of 270 ° C., a discharge rate of 642 g / min, and a speed of 700 m / min to obtain a core-sheath type undrawn fiber.
Next, the undrawn fiber is subjected to a drawing temperature of 60 ° C. and a draw ratio of 3.
After drawing at 8 times, crimping was performed with a press-in type crimping machine and cut to 51 mm to obtain a polyester-based heat-bondable fiber having a fineness of 4 denier. The PEN staple fiber thus obtained and the polyester-based heat-adhesive fiber were mixed at a ratio of 80:20, a web was formed with a card, and then laminated. After subjecting this laminated web to a thermal bonding treatment at 210 ° C. for 10 minutes, the thickness was regulated at 60 ° C. to a thickness of 35 mm. Then, crystallization heat treatment was performed at 110 ° C. for 20 minutes to obtain a fibrous structure.

Example 2 PEN short fibers and a fibrous structure were obtained in the same manner as in Example 1 except that a copolymerized polyester having a Tg of 103 ° C. obtained by copolymerizing isophthalic acid with PEN was used.

Examples 3 to 7 PEN short fibers and fibrous structures were produced in the same manner as in Example 1 except that the tension heat treatment temperature and the relaxation heat treatment temperature were changed as shown in Table 1 in the process of producing PEN short fibers. Obtained.

Comparative Example 1 A main fiber and a fiber structure were obtained in the same manner as in Example 1 except that a PET polymer having a Tg of 69 ° C. was used instead of the PEN polymer.

Comparative Example 2 The procedure of Example 1 was repeated except that a copolymerized polyester having a Tg of 73 ° C. and copolymerized isophthalic acid with PEN was used.
EN short fibers and fiber structures were obtained.

Comparative Examples 3 and 4 PEN short fibers and fibrous structures were prepared in the same manner as in Example 1 except that the tension heat treatment temperature and the relaxation heat treatment temperature were changed as shown in Table 1 in the process of producing PEN short fibers. Obtained.

Comparative Example 5 The procedure of Example 1 was repeated except that an amorphous polyester (Tg of 62 ° C., softening point of 110 ° C.) obtained by copolymerizing 40% by mole of isophthalic acid was used as an adhesive component of the heat-adhesive fiber. A heat-adhesive fiber and a fiber structure were obtained.

Example 8, Comparative Examples 6 and 7 A fibrous structure was obtained in the same manner as in Example 1 except that the mixing ratio of the PEN short fiber and the heat-adhesive fiber was changed as shown in Table 1.

Table 1 shows the measurement results of various physical properties of the main fibers and the fiber structures obtained in Examples 1 to 8 and Comparative Examples 1 to 7.

[0050]

[Table 1]

As is clear from Table 1, in Examples 1 to 8, the crimp retention of the main fiber was high, and the obtained fiber structure was excellent in the compression set at 70 ° C. However, it was difficult to be thermally deformed. On the other hand, in Comparative Example 1, the main fiber was PET short fiber, and the Tg was less than 80 ° C., and in Comparative Example 2, the Tg of PEN was less than 80 ° C., so that both crimp retentions were low and obtained. The resulting fibrous structure also had a high compressive residual strain rate and was easily deformed by heat. Also in Comparative Examples 3 and 4, since the crimp retention of the PEN short fiber was low, the obtained fiber structure had a high compression residual strain rate and was easily thermally deformed. In Comparative Example 5, since the adhesive component of the heat-bonding fiber was an amorphous polyester, the resulting fiber structure had a high compression set rate and was inferior in cushioning properties. In Comparative Example 6, since the mixing ratio of the heat bonding fibers was small, the fiber structure lost its shape when the performance of the fiber structure was measured, and the performance of the fiber structure could not be measured. In Comparative Example 7, since the mixing ratio of the main fibers was small, the obtained fibrous structure had a high compression residual strain rate, had poor resilience to compression, and had poor cushioning properties.

[0052]

The polyester short fiber of the present invention has a Tg
Is made of polyester having a temperature of 80 ° C. or higher, and is a polyester short fiber having a high retention rate of a crimp rate at a high temperature when producing a fibrous structure. The fibrous structure is less likely to be thermally deformed even when used in a high temperature atmosphere of about 70 ° C., and is particularly suitable as an automobile seat, a ceiling material, a floor material, a sound absorbing material, or a trunk room interior material.

Claims (3)

[Claims] 1. A polyester-based short fiber comprising a polyester having a glass transition temperature of 80 ° C. or higher, and having a retention rate of a crimp rate of 85% or higher before and after a heat treatment at 210 ° C. 2. A polyester thermoadhesive fiber 10 whose fiber surface is covered with a crystalline copolymerized polyester having a glass transition temperature of 20 to 80 ° C. and a melting point of 130 to 180 ° C.
50% by weight of the polyester staple fiber 9 according to claim 1.
A fiber structure comprising 0 to 50% by weight. 3. The fibrous structure according to claim 2, wherein a 25% compressive stress at a density of 20 to 40 kg / m ³ is 8 kgf or more, and a compressive residual strain at 70 ° C. is 20% or less.