JP2003193361A - Filament nonwoven fabric to be made into ultrafine fiber and wiping cloth using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a filament nonwoven fabric which is readily made into ultrafine fibers by applying mechanical stress to the nonwoven fabric without requiring a complicated process and suitable as wiping cloth having especially excellent wiping property. <P>SOLUTION: This nonwoven fabric is constituted of a filament that comprises a polyalkylene terephthalate in which 0.3-10 wt.% of a lactic acid-based polyester is dispersed and mixed and has a crosssectional shape of fiber of a form with a core part and a plurality of fin parts radially projected from the core part in the length direction of the core part. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrafine fiber non-woven fabric capable of easily separating a core part and a fin part by applying a mechanical stress, and a wiping cloth using the same. It is a thing.

[0002]

2. Description of the Related Art Conventional long-fiber non-woven fabrics have higher strength than short-fiber non-woven fabrics, and their manufacturing method does not require a series of large-scale equipment such as a raw cotton feeding section, an opening device, a card machine and a crosslay machine. Therefore, it is widely used for civil engineering, agriculture, daily life related materials, clothing, etc. In recent years, various fibers have been proposed in which the constituent fibers are made thinner to improve the quality and the performance based thereon.

In the spunbond method, which is one of the typical methods for producing long-fiber non-woven fabrics, a method is proposed in which a spun spinneret having a small pore size is used to draw out a discharged polymer stream at high speed in order to make the fiber ultrafine. However, in such a method, the single fiber fineness is limited to about 0.3 dtex, and it is technically difficult to produce ultrafine fibers smaller than this, and even if it is possible, productivity is improved. However, there is a problem that the cost is increased because of a significant decrease.

As another method, a non-woven fabric is formed by using composite fibers capable of generating ultrafine fibers such as sea-island type or peeling split type, which are composed of two or more components, and then the split fibers or one component Has been proposed (JP-A-3-213555, JP-A-5-331758, JP-A-49-1).
No. 4774, Japanese Unexamined Patent Publication No. 10-53948, Japanese Patent No. 2916590, etc.). However, in such a method, since it is necessary to perform composite spinning of a plurality of polymers, there are problems that the cost increases and the process becomes complicated.

On the other hand, in Japanese Unexamined Patent Publication (Kokai) No. 5-331758, a polyalkylene glycol component is blended with one component of a peelable split type composite fiber composed of a polyester component, and mechanical stress is applied in the presence of water. A method has been proposed in which each component is peeled and divided to form ultrafine fibers. However, this method requires a large amount of alkylene glycol to be blended, which leads to a decrease in the physical properties of the fiber and a disadvantage in terms of cost.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in the background of the above-mentioned prior art, and its object is to make ultrafine fibers easily by applying mechanical stress without requiring complicated steps. A long-fiber non-woven fabric suitable for a wiping cloth, which is particularly excellent in wiping property, can be provided.

[0007]

According to the study by the present inventors, the above-mentioned problem is a long-fiber nonwoven fabric made of polyalkylene terephthalate in which 0.3 to 10% by weight of lactic acid-based polyester is dispersed and mixed, A fiber cross-sectional shape of the long fiber is a shape having a core portion and a plurality of fin portions radially protruding from the core portion along the length direction of the core portion It has been found that a fibrous nonwoven can achieve this.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The polyalkylene terephthalate used in the present invention has terephthalic acid as a main acidic component,
It is a fiber-forming polyester containing alkylene glycol such as ethylene glycol, trimethylene glycol, tetramethylene glycol as a main glycol component, and among them, polyethylene terephthalate is preferable from the viewpoint of price and versatility.

The polyester may be copolymerized with components other than those mentioned above within the range not impairing the object of the present invention, and the proportion thereof is usually 10 mol% or less based on the total acid components. Examples of the copolymerizable component include, as acid components, aromatic dicarboxylic acids such as isophthalic acid, diphenyldicarboxylic acid and naphthalene dicarboxylic acid, aliphatic dicarboxylic acids such as succinic acid, adipic acid and sebacic acid, parahydroxybenzoic acid, 4 Examples thereof include oxycarboxylic acids such as-(β-hydroxyethoxy) benzoic acid, and a copolymer component having a sulfonate group is also preferably used from the viewpoint of fiber splittability. On the other hand, as the diol component, 1,6
-Hexane diol, aliphatic diol such as neopentyl glycol, 1,4-bis (β-hydroxyethoxy)
Examples thereof include aromatic diols such as benzene, polyalkylene glycols such as polyethylene glycol and polybutylene glycol. These components may be copolymerized alone or in combination of two or more.

Further, if the polymerization degree (intrinsic viscosity) of the polyester is too large or too small, the process stability during spinning tends to be low, and it becomes difficult to obtain a fiber having a cross-sectional shape described later. Therefore, the intrinsic viscosity (IV) measured at 35 ° C. in orthochlorophenol is 0.35 to
A range of 0.75, preferably 0.40 to 0.70 is suitable.

In the present invention, it is essential that the lactic acid-based polyester is dispersed and mixed in the above polyester, whereby the fiber having a cross-sectional shape consisting of a core portion and a fin portion, which will be described later, has no mechanical stress. By making it act, the space between the core portion and the fin portion can be easily divided to form an ultrafine fiber.

The lactic acid-based polyester used in the present invention is a polyester containing lactic acid as a main repeating unit, and examples of such polyester include poly L-lactic acid homopolyester, poly D-lactic acid homopolyester, and L-lactic acid / D-lactic acid. Examples thereof include polyesters consisting of lactic acid alone such as copolymerized polyesters, and polyesters obtained by copolymerizing 50% by weight or less of one or more copolymerization components with these lactic acids. As the copolymerization component preferably used, for example, ethylene glycol, butanediol,
Hexanediol, octanediol, decanediol and other diols, succinic acid, adipic acid, sebacic acid and other dicarboxylic acids, hydroxyalkyl carboxylic acids, pivalolactone, caprolactone and other aliphatic lactones,
Examples include polyethylene glycol. When the above components are copolymerized, it is necessary that the diol component and the dicarboxylic acid component have substantially the same amount.

The mixing ratio of the lactic acid-based polyester to be dispersed and mixed in the above-mentioned polyalkylene terephthalate needs to be in the range of 0.3 to 10% by weight based on the weight of the obtained composition. The mixing ratio of lactic acid type polyester is 0.3
If it is less than 10% by weight, the easy-dividing property which is the object of the present invention cannot be obtained. On the other hand, if it exceeds 10% by weight, the spinnability becomes poor and it becomes difficult to stably obtain fibers. A more preferable mixing ratio is in the range of 1.0 to 5.0% by weight.

The method of dispersing and mixing the lactic acid type polyester in the polyalkylene terephthalate is optional, and the method of adding the other polyester at the end of the polymerization of one of the polyesters and the method of adding each polyester during the melt spinning of the fiber. Any method such as a method of melting and kneading after mixing and a method of kneading each separately melted polyester before melt spinning may be adopted.

In the above polyester mixture, a release agent, a fluidity improver, a water repellent, a hydrophilic agent, and
Stabilizers, antioxidants, pigments, colorants, various inorganic particles, and other improving agents can be added.

Next, as shown in FIG. 1, the fibers constituting the ultrafine fiber non-woven fabric of the present invention have a fiber cross-sectional shape along the core portion and the length direction of the core portion. It is necessary to have a shape having a plurality of fin portions radially protruding from the core portion. Here, the shape of the core part is
It may have any shape such as a circular shape, an elliptical shape, and a polygonal shape, but generally it may have a substantially circular shape. On the other hand, since the fin portion has a rod shape, mechanical stress is apt to be applied in the dividing step of dividing the fin portion and the core portion by applying a mechanical stress, which will be described later, and the fin portion and the core portion are likely to be applied. Is preferable because it is easy to divide, and in particular, the ratio DA / WB of the circumscribed circle DA of the core part and the maximum width WB of the fin part
Is preferably in the range of 4-8. Further, the number of fin portions relative to the core portion is preferably 2 to 12, and more preferably 4
~ 8 pieces. If the number of fins is less than two, the effect is poor even if the fins are divided, and it becomes difficult to obtain the feeling and wiping effect based on the ultrafine fibers. On the other hand, when the number exceeds 12, the formation becomes difficult.

The ratio of the area (SA) of the core portion surrounded by the boundary between the core portion and the fin portion (circumscribing circle when the core portion is not a perfect circle) to the area (SB) of one fin portion (SB /
SA) cannot be said unequivocally due to the number of fins,
A range of 0.05 to 0.5 is suitable. This ratio is 0.0
If it is less than 5, the fin portion is too small and thus the ultrafine fibers are not sufficiently advanced in the dividing step. On the other hand, if it exceeds 0.5, the fibers of the core portion are easily cut in the dividing step. The strength of the resulting ultrafine fiber nonwoven fabric is reduced. The preferable area ratio range is 0.1 to 0.3.
Is. The specific core fineness is 1-6 dte.
x, preferably 1 to 4 dtex, the fineness of each fin portion is 0.05 to 1 dtex, preferably 0.1 to 0.4 dt
A range of ex is preferred. Here, if the fineness of each fin is too large, the texture based on the ultrafine fibers becomes insufficient,
On the other hand, if the fineness of the core portion becomes too small, the stability during spinning will decrease.

The long-fiber nonwoven fabric capable of forming ultrafine fibers of the present invention described above can be produced, for example, by the following method. That is, the lactic acid-based polyester is 0.3 to 1
When melt-spinning polyalkylene terephthalate in which 0% by weight is dispersed and mixed, for example, as shown in FIG. 2, core-portion-forming ejection holes and a plurality of fin-form slit-shaped ejections spaced around the ejection holes are formed. It can be obtained by using a spinneret in which holes are arranged and joining the polymer discharged from each hole in a molten state immediately after discharging. In this case, since the polymer discharged from the fin-shaped slit-shaped discharge holes requires a larger spinning draft than the polymer discharged from the core-shaped discharge holes, the molecular orientation between the fin portion and the core portion is high. Because they are different
It is presumed that the bonding force at the interface between the two is weak. Furthermore, since lactic acid-based polyester having low compatibility is mixed with polyalkylene terephthalate, which is a main component, if the lactic acid-based polyester is present at the interface, it becomes possible to more easily split when stress is applied. Presumed.

The long fibers spun as described above may be spun-bonded, or the spun yarn may be stretched and once wound, and then spun on a porous collecting surface while opening with a high-speed traction fluid. It is made into a web by a conventionally known method such as a method of collecting as. Among them, the spunbond method, in which the yarn spun from the spinneret is pulled at a high speed and jetted / collected on the collecting net, is particularly preferable from the viewpoint of productivity. Here, the range of 2000 to 8000 m / min is suitable as the high-speed pulling speed, and the range of 3000 to 6000 m / min is particularly preferable, and the long fibers discharged from the spinneret are controlled within the above range by an ejector or an air sucker. Just pull at high speed. The thin filaments obtained by high-speed drawing are collected on the collecting net while being opened. At that time, it is preferable to charge and open the fiber by a conventionally known method such as charging by corona discharge or contact charging.

When collecting the thin long fibers on the net, other short fibers may be mixed within a range not impairing the object of the present invention, or other long fibers may be laminated. , May be mixed. There is no particular limitation on the materials of the mixed cotton or the laminated or mixed fibers, for example, regenerated fibers such as rayon, semi-synthetic fibers such as acetate, natural fibers such as wool,
Any one or two of polyamide fibers such as nylon-6 and nylon-66, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, and polyolefin fibers such as polyethylene and polypropylene.
It is possible to select and use one or more species. Of course, the cross-sectional shape and the like of the fiber are not particularly limited, and the core-sheath type composite fiber in which the above-mentioned thermoplastic resins are combined, the separation split type composite fiber,
Any fibers can be used, such as fibers having a modified cross section.

The ultrafine-fiber-formable long-fiber nonwoven fabric of the present invention thus obtained may be obtained by accumulating a plurality of sheets or by themselves, preliminarily heat-bonding them if necessary, and once winding them. Alternatively, by continuously applying mechanical stress as it is, the core portion and the fin portion can be easily separated and separated, and an ultrafine fiber nonwoven fabric can be obtained. In addition, by performing a high-pressure hydroentanglement treatment or a needle punching treatment to form an entangled nonwoven fabric, or by thermally adhering it partially by thermocompression bonding, the strength of the obtained ultrafine long fiber nonwoven fabric is improved,
It is particularly preferable when it is put to practical use such as a wiping cloth.
However, if the fiber entanglement treatment or thermal adhesion treatment is performed after the division treatment, the fibers may be damaged and easily cut. Therefore, when used as a wiping cloth, it may cause dust generation. Therefore, it is preferable to perform the division processing simultaneously with or before the division processing.

The ratio of separation of the core portion and the fin portions by applying mechanical stress must be 30% or more of the total number of fin portions. If the separation ratio is less than 30%, the function and texture of the ultrafine fibers are lacking, which is not preferable. Above all, the separation ratio is preferably 50% or more, and more preferably 70% or more.

The method of applying mechanical stress is not particularly limited as long as it can divide the core portion and the fin portion to form the ultrafine fibers, and a plurality of methods may be combined. Examples of the mechanical division treatment method include a method of applying pressure between rollers, a method of performing ultrasonic treatment, a method of giving an impact, a method of rubbing treatment, and a method of performing high-pressure columnar water flow treatment. In addition, the method by the high-pressure columnar water treatment, even if not subjected to the confounding treatment in advance,
It is preferable because the fibers can be divided and entangled at the same time. However, if the basis weight of the nonwoven fabric to be treated is too large, it becomes difficult to form divided five fine fibers. Therefore, a method of applying pressure after the entanglement treatment or a method of performing rubbing treatment is preferable. Of course, any of the above methods may be combined with another method of forming ultrafine fibers.

[0024]

EXAMPLES The present invention will be described in more detail below with reference to examples. The parts and% in the examples and comparative examples are by weight unless otherwise specified, and the physical properties are measured by the following methods. (1) Intrinsic viscosity Orthochlorophenol was used as a solvent and measured at 35 ° C. (2) Fineness before division Measured according to JIS-L1015 7-5-1A method. (3) Using a Pierce-2 (manufactured by Pierce Co., Ltd.), which is an area ratio image analysis system for the core and fins, a section cross-sectional image of the single fiber before division is magnified 500 times, and the cross-sectional area of the core of the fiber is enlarged. (SA) and fin section cross-sectional area (SB) were measured and determined from the following equation. Area ratio of core part and fin part = SB / SA

(4) Dividing ratio For the ultrafine fiber non-woven fabric which can be made into ultrafine fibers before the dividing treatment, a pair of flat metal rollers (room temperature) is used.
After nipping at a linear pressure of 686 N (70 kg) / cm for 5 times and then dividing the resulting ultrafine fiber nonwoven fabric, the cross section of the nonwoven fabric is directly observed with an electron microscope.
The image was taken at 00 times, the cross section of 50 fibers was measured, and it was determined by the following formula from the number of separated fin portions and the total number of fin portions. Division ratio (%) = (number of separated fin portions) / (total number of fin portions) × 100 (5) Wiping-off coloring liquid (Suminol Fast Blue 4G)
L: 0.2%, water: 20.0%, ethylene glycol (polymerization degree 300): 79.8%), 30 cm × 20 c
After uniformly coating on an acrylic plate having a size of m with a screen printing stage, 1.96 is applied on the acrylic plate.
An 8 cm × 6 cm sample loaded with N (200 g) was slid at 500 mm / min, and the ratio of the coloring liquid remaining on the acrylic plate was measured after taking a photograph, and the result was as follows. Indicated. ◯: The residual liquid on the acrylic plate is less than 20% of the coating amount. ×: The residual liquid on the acrylic plate is 20% or more of the coating amount.

Examples 1 to 3 and Comparative Examples 1 to 4 Polyethylene terephthalate having a titanium oxide content of 0.5% by weight and an intrinsic viscosity of 0.64 (manufactured by Teijin Ltd .: melting point 258 ° C.)
And polylactic acid (Lacti manufactured by Shimadzu Corporation: melting point 17)
5 ° C. and a weight average molecular weight of 200,000) were melt-kneaded with a biaxial kneader so that the content of polylactic acid was as shown in Table 1, and the polymer temperature was 277 ° C. ), A spinneret having core-portion-forming discharge holes having a circular cross section and four fin-portion-forming discharge holes arranged at equal intervals around the core-portion-forming discharge holes (the number of fins in Example 3 and Comparative Examples 3-4). The discharge amount per single hole was 2 g / min, and high-speed towing was performed at an air pressure of 0.35 MPa.
A high-voltage application process of 30 kV was applied, and then the fibers were collided with an air flow to open the filaments, and were collected by a collecting net conveyor as a web having a width of 1 m. The web thus obtained was continuously heat-bonded by an embossing calender at 150 ° C. above and below to obtain a nonwoven fabric having a basis weight of 100 g / m ² . Table 1 shows the evaluation results of this nonwoven fabric.

[0027]

[Table 1]

Examples 4 to 6 and Comparative Examples 5 to 7 Polyethylene terephthalate having a titanium oxide content of 0.5% by weight and an intrinsic viscosity of 0.64 (manufactured by Teijin Ltd .: melting point 258 ° C.)
And polylactic acid (Lacti manufactured by Shimadzu Corporation: melting point 17)
5 ° C. and a weight average molecular weight of 200,000) were melt-kneaded using a biaxial kneader so that the content of polylactic acid was as shown in Table 2, and the polymer temperature was 277 ° C. ), A spinneret having core-portion-forming discharge holes having a circular cross section and four fin-portion-forming discharge holes arranged at equal intervals around the core-portion-forming discharge holes (the number of fins in Example 6 and Comparative Examples 7 to 8) The discharge amount per single hole was 2 g / min, and high-speed towing was performed at an air pressure of 0.35 MPa.
A high-voltage application process of 30 kV was applied, and then the fibers were collided with an air flow to open the filaments, and were collected by a collecting net conveyor as a web having a width of 1 m. The obtained web was continuously heat-bonded with an embossing calendar of 150 ° C. above and below, and then supplied on a mesh-shaped screen moving at a speed of 10 m / min to give water,
The splitting process was performed by a high-pressure (7.5 × 10 ³ kPa) water stream. At that time, the hole diameter of the high-pressure water jet is 0.1
mm, the number of holes = 601, the hole pitch = 1 mm, and the injection hole group row = 6 rows, and the web was passed through the front and back sides once. After this, water is squeezed with a mangle roll and treated with a drying / heat treatment device kept in an atmosphere of 98 ° C. to give a basis weight of 80 g / m 2.
² ultra-fine long-fiber nonwoven fabric was obtained. Table 2 shows the evaluation results of this nonwoven fabric.

[0029]

[Table 2]

[0030]

INDUSTRIAL APPLICABILITY The long-fiber nonwoven fabric capable of being made into ultrafine fibers of the present invention is divided by being subjected to mechanical stress so that cracks are easily generated (in the fiber axis direction) between the core part and the fin part. It can be made into ultrafine fibers and can be easily manufactured by using the conventional method and apparatus for manufacturing a long-fiber nonwoven fabric. In addition, the resulting ultrafine long-fiber nonwoven fabric has excellent texture, heat retention, wipeability, and filterability, so it is used in a wide range of applications such as clothing, wipers, filters, high-quality printed paper, and artificial leather. Can be done, and its industrial significance is great. Especially in the application of wiping cloth, it has excellent wiping and handling properties.

[Brief description of drawings]

1A and 1B are schematic views each showing an example of a discharge hole shape of a spinneret used in the present invention.

FIG. 2 is a schematic view showing an example of a cross section of a fiber capable of being made into an ultrafine fiber according to the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4L035 BB31 DD02 DD13 FF05                 4L045 AA05 BA10 BA34 CA05 CB02                 4L047 AA21 AB03 AB08 AB09 BA04                       CC16

Claims (6)

[Claims] 1. A long-fiber nonwoven fabric made of polyalkylene terephthalate in which 0.3 to 10% by weight of lactic acid-based polyester is dispersed and mixed, and the cross-sectional shape of the fibers of the long fiber is a core portion and a length of the core portion. A long-fiber non-woven fabric capable of being made into ultrafine fibers, which has a shape having a plurality of fin portions radially protruding from a core portion along a direction. 2. The continuous fiber non-woven fabric according to claim 1, wherein the ratio SB / SA of the cross-sectional area SA of the core portion and the cross-sectional area SB of the fin portion is 0.05 to 0.5. 3. The continuous fiber non-woven fabric according to claim 1, wherein the ratio DA / WB of the circumscribed circle diameter DA of the core portion and the fin portion maximum width WB is 4 to 8. 4. A polyalkylene terephthalate in which lactic acid-based polyester is dispersed and mixed in an amount of 0.3 to 10% by weight, and a fiber cross-sectional shape is radial from the core part and the core part along the length direction of the core part. An ultrafine long-fiber nonwoven fabric characterized in that long fibers having a shape having a plurality of protruding fin portions are separated from the core portion by at least 30% of the fin portions due to the action of mechanical stress. 5. The ultrafine fiber long-fiber nonwoven fabric according to claim 4, which has been subjected to an entanglement treatment or an adhesive treatment. 6. A wiping cloth made of the ultrafine long-fiber nonwoven fabric according to claim 4 or 5.