JPH0892851A - Nonwoven fabric excellent in bulkiness-recovering property and winding up of the nonwoven fabric - Google Patents

Abstract

PURPOSE: To obtain a nonwoven fabric greatly excellent in the bulkiness- recovering property after compression in comparison with conventional bulky nonwoven fabrics. CONSTITUTION: Polybutylene terephthalate and high density polyethylene are used as a core component and a sheath component, respectively, to produce eccentric type conjugate fibers 1. The conjugate fibers are thermally treated to express spiral crimps on the fibers. The web of the crimped fibers is treated with hot air to produce a bulky nonwoven fabric 4 wherein the sheath component parts of the fibers are combined to each other to form linkages 3A, 3A. The bulky nonwoven fabric 4 has a specific volume of >=130cm<3> /g and a bulkiness-recovering property comprising a thickness-recovering property of >=20%. based on the initial thickness just after compressed to a thickness of approximately 1/30 based on the apparent thickness for 24hr and also a thickness-recovering property of >=75% based on the initial thickness after 24hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-woven fabric having excellent bulk recoverability, which recovers the bulkiness close to that before winding when it is unwound from a rolled state for a long time.

[0002]

2. Description of the Related Art A composite fiber composed of two kinds of synthetic polymers having different heat shrinkability develops a two-dimensional crimped fiber or a three-dimensional crimped fiber by heat treatment. It has been widely known that a nonwoven fabric excellent in bulkiness can be obtained by using a three-dimensional crimped fiber. For example, Japanese Examined Patent Publication No. 3-20505, or Japanese Patent Laid-Open No. 2-191.
As described in Japanese Patent Publication No. 720, it is preferable that a core-sheath type or dorsoventral type composite fiber using polypropylene as the first component and polyethylene or an ethylene propylene random copolymer as the second component is suitable as a bulky nonwoven fabric. It has been known.

In recent years, with the widespread use of sanitary materials such as sanitary napkins and disposable diapers, various kinds of non-woven fabrics have been applied to these products, and the specific volume is 100 cm ³ per part in order to enhance the feeling of wearing. A bulky non-woven fabric having a weight ratio of more than / g is used.

[0004]

However, the conventional bulky nonwoven fabric used for the above sanitary materials can exhibit a soft cushioning effect which is satisfactory in the early stage of wearing, but is poor in bulk recovery. The product loses its bulkiness over time when compressed into a compact packaging form for distribution from a product that has been compressed and stored for a long time.
It has the drawback that it is not possible to maintain the same bulkiness and good wearing feeling as during manufacturing.

The above problems can be improved to some extent in a non-woven fabric made of fibers having a spiral three-dimensional crimp, but for example, a tertiary obtained by heat treating a conventional composite fiber made of polypropylene and polyethylene. In the non-woven fabric made of the original crimped fiber, the specific volume is 130
It is possible to obtain a bulky non-woven fabric that reaches cm ³ / g, but the bulk recovery rate after compressing the non-woven fabric for 24 hours is 70% or less of the thickness before compression, which is by no means sufficient. Absent.

In general, when applying a bulky nonwoven fabric to a product, a long bulky nonwoven fabric obtained by heat treatment is wound into a roll, stored, transported to a place of use, and then unwound and used successively. . In the case of winding into a roll, the bulky nonwoven fabric is compressed while being reduced in volume to improve the storage space and transportation efficiency. For this reason, non-woven fabrics with poor bulk recovery properties do not recover to near the bulky state during manufacturing when rewound for use, and the products obtained have a soft wearing feel like bulky nonwoven fabrics during manufacturing. I can't.

An object of the present invention is to provide a non-woven fabric which is much more excellent in bulk recoverability than conventional bulky non-woven fabrics, and another object is to roll it into a roll without impairing the bulk recoverability of the bulky non-woven fabric. To provide a way to take.

[0008]

DISCLOSURE OF THE INVENTION The present invention finds that an eccentric core-sheath type composite fiber is extremely effective in improving bulk recovery, using polybutylene terephthalate as a core component and high-density polyethylene as a sheath component, The above problem was solved by forming a nonwoven fabric from this composite fiber and then heat treating it to bond the fibers with a sheath component.

That is, the nonwoven fabric excellent in bulk recovery of the present invention is
The eccentric core-sheath type composite fiber web having a spiral crimp in which the core component is polybutylene terephthalate and the sheath component is high-density polyethylene, has a specific volume which is heat-bonded in the sheath component portion. 130 cm ³ / g
The above non-woven fabric, which is about 1/30 of the apparent thickness
In addition, the thickness recovery rate immediately after compression for 24 hours is 20% or more of the initial thickness, and the thickness recovery rate after 24 hours is 75% or more of the initial thickness.

Further, the method for winding a bulky nonwoven fabric according to the present invention is a method in which interfiber fibers of an eccentric core-sheath type composite fiber web having a spiral crimp having a core component made of polybutylene terephthalate and a sheath component made of high density polyethylene. However, the specific volume formed by heat bonding at the sheath component is 130 cm ³
/ G or more non-woven fabric, which is about 1 / th of its apparent thickness
The thickness recovery rate immediately after compression for 30 to 24 hours is 20% of the initial thickness.
% Or more and the thickness recovery rate after 24 hours is 75% or more of the initial thickness, the nonwoven fabric of the present invention is characterized in that the nonwoven fabric temperature is cooled to less than 60 ° C. and wound into a roll. .

The composite ratio (core component: core component: polybutylene terephthalate) of the core component of the eccentric core-sheath type composite fiber constituting the nonwoven fabric excellent in bulk recovery of the present invention and the high density polyethylene of the sheath component (core component: The sheath component) is 70 to 30: 3.
Within the range of 0 to 70, a desired spiral crimp can be developed by heat treatment. If the number of crimps is 20/25 mm or more, the specific volume is 130
A bulky nonwoven fabric having a cm ³ / g or more can be obtained, and a good bulk recovery property is exhibited after heat bonding.

The non-woven fabric of the present invention in which the fibers of the eccentric core-sheath type composite fiber web having the above-mentioned spiral crimp are heat-bonded to each other in the sheath component part thereof has a basis weight of 1
At 0 g / m ² , the apparent thickness is 1.3 mm or more and the specific volume is 130 cm ³ / g or more.
Therefore, since it has a relatively low basis weight, it has a large apparent thickness and is excellent in bulk recovery after compression and opening. Therefore, it is 10 to ²⁰ g / m ² for sanitary materials and 30 to 50 g / m ² for heat retention. ^{About 2} can be preferably applied.

The eccentric core-sheath type composite fiber having spiral crimps constituting the nonwoven fabric of the present invention has a high melting point and is a fiber forming component polybutylene terephthalate (melting point 22.
4 ° C) and 50 more than this polybutylene terephthalate
High-density polyethylene with a low melting point above ℃ (melting point 135-1
(37 ° C.), which is a thermo-adhesive conjugate fiber composed of a self-adhesive component, and is maintained in a crimped state by heat treatment at a temperature not lower than the melting point of the low melting point component and not higher than the melting point of the high melting point component by 50 ° C. The fibers can be bonded together in the state, and the nonwoven fabric thus obtained is remarkably superior in bulk recoverability to conventional bulky nonwoven fabrics.

When the above-mentioned nonwoven fabric of the present invention having an excellent bulk recovery property is wound into a roll while being pressed and then used by being pulled out from the roll, the nonwoven fabric which is still in a high temperature state immediately after the heat treatment is wound into the roll. It is important to cool the nonwoven fabric to some extent, preferably to a temperature of 60 ° C. or lower, and then wind it. When a non-woven fabric still in a high temperature state immediately after heat treatment is wound up or wound into a roll while pressing it at a temperature of 60 ° C. or more without being sufficiently cooled, the bulk recovery rate of the non-woven fabric taken out from the roll is 70%. If it is less than 1, the bulk recovery property will be hindered.

In order to cool the non-woven fabric after heat treatment to a temperature of 60 ° C. or lower, for example, a porous machine such as a porous punching plate, a suction drum provided with a wire mesh, or a metal net conveyor is used after a heat-bonding machine. It is advisable to provide a conveying means and forcibly cool it with cooling air while transporting the non-woven fabric immediately after adhesion processing onto this porous transporting means, or to transport the non-woven fabric while bringing the non-woven fabric into contact with the surface of the water-cooling roll. When such a cooling means is not used, the non-woven fabric is soft-rolled with a low tension of, for example, about 0.5 to 1.0 kg, and then allowed to stand and then naturally cooled so as not to be greatly compressed in the thickness direction. Then, it is recommended to rewind to a hardness suitable for transportation and handling while pressing.

[0016]

The core component polybutylene terephthalate retains the spirally crimped fiber form, and the sheath component high-density polyethylene acts as an adhesive component for fiber-to-fiber bonding by heat treatment. Tightly connect the intersections of. The non-woven fabric in which the fibers are bonded together imparts bulkiness to the non-woven fabric by the elasticity of the individual spirally crimped fibers, and the elasticity of the individual spirally crimped fibers improves the bulk recoverability after compression.

[0017]

EXAMPLE FIG. 1 is an enlarged view of an eccentric core-sheath type composite fiber (1) having spiral crimps, which constitutes the nonwoven fabric of the present invention, in which (2) is a core component and (3) is a sheath. It is an ingredient. Further, FIG. 2 shows the nonwoven fabric of the present invention in which the above composite fiber web is heat-treated and bonded at the low melting point component portions (3A) and (3A) of the composite fiber (1).
FIG. 3 is an enlarged view of (4), and FIG. 3 is an enlarged view showing a state where the nonwoven fabric (4) of FIG. 2 is pressed in the thickness direction.

[Examples 1 to 3, Comparative Examples 1 to 4] (1). The following resins were prepared as core components (high melting point components). Resin A: Polybutylene terephthalate having a melting point of 224 ° C. and an IU value of 0.75 (manufactured by Polyplastics Co.) Resin B: 98% by weight of HI, 97 mol% of IPF, MFR2
Highly crystalline polypropylene resin 0 g / 10 minutes, melting point 165 ° C., Q value 9.5 resin C: melting point 258 ° C., density 1.38 g / cm ³ , 27
Polyethylene terephthalate with MFR 45g / 10 minutes at 0 ° C (2). The following resin was prepared as a sheath component (low melting point component). Resin D: melting point 137 ° C., density 0.964, MI 17 g /
10 minutes high density polyethylene resin E: melting point 135 ° C., density 0.956, MI 13 g /
10 minutes high density polyethylene resin F: melting point 123 ° C., density 0.926, MI 20 g /
10 minutes of medium density polyethylene

Eccentric type core-sheath type composite fibers were melt-spun using the above resin under the conditions shown in Table 1 at a spinneret number of 500 and a discharge rate of 150 g / min per 1 spindle, and subsequently 60 to 60 after spinning. 80
Draw in warm water at ℃, apply mechanical crimp with a stuffer box, and 80-110 ℃ with a net conveyor dryer.
Was dried at a temperature of, and the staple was cut into a cut length of 51 mm. The obtained fiber performance was measured by a conventional method. The measurement results are shown in Table 1. The crimp shape of the fiber before the heat treatment is indicated by M, S, and C. However, M is a shape of the mechanical crimp, S is a spiral shape, and C is a shape in which the mechanical crimp and the spiral crimp are mixed.

Next, each fiber was heated at 130 ° C. for 55 seconds to develop crimps. The crimp shape of each fiber was spiral and the number of crimps was as shown in Table 1. Note that the crimp shape is visually observed using a magnifying glass with the fibers left unloaded, and the number of crimps is 25 for each 10 fibers.
The average number of crimps per hit is shown.

Next, each of the above fibers was applied to a roller card to form a web, which was heat-bonded by a hot air penetrating heating machine at 145 ° C. to obtain a heat-bonded nonwoven fabric having a basis weight of 30 g / m ² . After each non-woven fabric was left to stand overnight, its thickness was measured and used as the initial thickness A (mm). Next, each non-woven fabric has a thickness of 0.1 m
It was compressed with a weight of m and left for 7 days. Then, after 7 days, the weight was released, the thickness immediately after that and the thickness B after the lapse of 24 hours were measured, and A / B × 100 (%) was calculated to obtain the bulk recovery rate.

[0022]

[Table 1]

Subsequently, the nonwoven fabric of Example 1 (initial thickness 4.9)
(mm) is transferred to another continuous net conveyor immediately after the hot air treatment, and the surface temperature of the nonwoven fabric is 40 ° C. with 10 ° C. cold air.
Cooled to. Then, the nonwoven fabric was tightly wound into a roll at a pressure of 12 kg / m. For comparison, the non-woven fabric of Example 1 was immediately cooled with hot air immediately without cooling.
The roll was tightly wound at a pressure of 2 kg / m. Then, each of the rolled non-woven fabrics was allowed to stand for 7 days, then unwound from the roll, and the thickness of each was measured.
The thickness of the cooled non-woven fabric was 3.6 mm, but the thickness of the non-woven fabric rolled in the hot state was 0.7 mm,
The effect of rapid bulk recovery by cooling was confirmed.

[0024]

As described above, in the bulky nonwoven fabric of the present invention, the fibers of the eccentric core-sheath type composite fiber web having spiral crimps in which the core component is polybutylene terephthalate and the sheath component is high-density polyethylene are , The non-woven fabric heat-bonded in the sheath component portion, the core component is polypropylene, the sheath component is a eccentric core-sheath type composite fiber web having a spiral crimp made of high-density polyethylene, The bulk recovery property is far superior to that of a conventional typical bulky nonwoven fabric in which the sheath component is heat-bonded.

From Table 1 showing examples of the present invention, for example, a non-woven fabric having a low fabric weight of about 10 g / m ² and an apparent thickness of about 1.3 mm (specific volume 130 cm ³ / g) is selected. Even when created, the thickness recovery rate immediately after compression for 24 hours is 20% or more of the initial thickness, and the thickness recovery rate after 24 hours is 75% of the initial thickness to about 1/30 of the apparent thickness. It is also clear that a nonwoven fabric excellent in bulk recoverability as described above can be obtained, and such a nonwoven fabric having a low basis weight and excellent in bulk recoverability is particularly suitable for sanitary materials.

Therefore, when such a non-woven fabric having high bulkiness and excellent bulk recovery property is used by being interposed between a sanitary material such as a surface sheet of an absorbent article and an absorbent material, the nonwoven fabric conforms to the body shape of the wearer. This has the effect of flexibly joining the joints and accurately maintaining the joined state even when the compressed state of the joined portion changes from moment to moment.

The nonwoven fabric of the present invention having an excellent bulk recovery property is cooled to a temperature of less than 60 ° C. and wound into a roll, so that even if the nonwoven fabric is compressed under pressure at the time of winding, the roll is rolled. When unwound from the non-woven fabric and taken out, the non-woven fabric is restored to a bulky state and can be used as a non-woven fabric having excellent bulk recoverability.

[0028] Such a characteristic is that it is not necessary to manufacture a fabric having a large basis weight in consideration of the settling of the thickness at the time of roll winding as in the prior art, and it can be wound tighter than a conventional nonwoven fabric of the same thickness. Therefore, when the roll is wound to the same diameter, the winding length can be remarkably increased, which is useful for reducing distribution costs such as transportation and storage.

[Brief description of drawings]

FIG. 1 is an enlarged view of an eccentric core-sheath type composite fiber having a spiral crimp, which constitutes the nonwoven fabric of the present invention.

FIG. 2 is an enlarged view of a bonded portion of a nonwoven fabric after heat treatment.

FIG. 3 is an enlarged view showing a state where the nonwoven fabric of FIG. 2 is pressed in the thickness direction.

[Explanation of symbols]

 1. Eccentric core-sheath type composite fiber 2. Core component 3. Sheath component 4. Bulky non-woven fabric

[Procedure amendment]

[Submission date] December 28, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

FIG.

[Fig. 2]

[Figure 3]

Claims (2)

[Claims] 1. A core component of polybutylene terephthalate,
The eccentric core-sheath type composite fiber web having a spiral crimp whose sheath component is made of high-density polyethylene or medium-density polyethylene is heat-bonded to each other in the sheath component to have a specific volume of 130 cm ³ / It is a bulky non-woven fabric with a weight of g or more, and is about 1/30 of its apparent thickness
The thickness recovery rate immediately after time compression is 20% or more of the initial thickness, 2
A nonwoven fabric excellent in bulk recovery, characterized in that the thickness recovery rate after 4 hours is 75% or more of the initial thickness. 2. A method for winding a non-woven fabric having excellent bulk recovery, comprising winding the non-woven fabric according to claim 1 to a non-woven fabric temperature of less than 60 ° C. and winding the roll into a roll.