JPH04174753A - Nonwoven filament cloth - Google Patents

Abstract

PURPOSE:To provide the subject nonwoven cloth composed of a single polymer and having excellent bulkiness by specifying the crosssectional shape of a constituent filament having denier unevenness in longitudinal direction. CONSTITUTION:A multifilament of eccentric hollow filament having denier unevenness in longitudinal direction is heat-treated at 150450 deg.C to effect the development of crimp and the objective nonwoven cloth is produced from the treated multifilament. The filament has a flat cross-section asymmetric with respect to the minor axis (c) and having a pair of recesses X, X' on the outer circumference in the direction of the major axis (n). The hollow part (e) is positioned in a part (g) having the maximum dimension parallel to the minor axis (c). The orientation degree of the part (g) is larger than that of the part (h).

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a long fiber nonwoven fabric with excellent bulkiness. More specifically, the present invention relates to a long-fiber nonwoven fabric with excellent bulkiness, which is made of crimped fibers that are obtained by heat-treating filaments that have a shrinkage difference in the cross-sectional direction.

(Conventional technology) In recent years, nonwoven fabrics have been used in a wide range of fields.

However, there are many different processes and methods for manufacturing nonwoven fabrics.
It cannot be denied that the conditions used and the product characteristics limited by these conditions impose limitations on the use of the nonwoven fabric.

For example, in stable nonwoven fabrics, various raw materials and short fibers with different shapes can be easily provided, but generally,
The reality is that the process of opening the cotton and forming the web is highly difficult, and there are some limitations due to the mechanical and practical characteristics of the product, such as its toughness and durability. .

On the other hand, the method of making continuous filament nonwoven fabric (spunbond method), in which a sheet-like material is created in one step from raw resin, is not only an economical manufacturing method, but also eliminates the difficulty of processing single fibers. Therefore, it has the advantage that it can be easily made from thick to thin materials, and efforts are being focused on its development as a tough nonwoven fabric and a nonwoven fabric with special functionality.

However, in the conventional spunbond method, it is difficult to crimp the raw yarn, and the fibers are simply laminated, resulting in a hard nonwoven fabric with no bulk. In order to solve this problem, for example, a nonwoven fabric made of bimetallic composite fibers (side-by-zide type or eccentric core-sheath type conjugate 1-thread) has been proposed in Japanese Patent Publication No. 45-2345. Since it is necessary to increase the number of discharge holes, the equipment becomes extremely complicated and the capital investment is large, resulting in an expensive nonwoven fabric and a significant loss of economic efficiency.
In addition, it becomes difficult to uniformly discharge the polymer into the multiple discharge holes, which not only deteriorates the spinnability but also makes it difficult to obtain single fibers with uniform physical properties, resulting in high bulk at a low cost that can withstand practical use. It has been difficult to obtain long fiber nonwoven fabrics.

(Objective of the Invention) The present invention was made to overcome the drawbacks of the above-mentioned prior art, and its purpose is to provide a long-fiber nonwoven fabric with excellent bulkiness at a low cost while using a single polymer. It is in.

(Structure of the Invention) In order to achieve the above object, the present inventors have made extensive studies focusing on the discharge state of the polymer near the spinneret.
It was discovered that under certain conditions, even a single polymer can produce fibers with good crimp development properties, and that if such fibers are made into a nonwoven fabric, a long fiber nonwoven fabric with excellent bulkiness can be obtained. As a result of further investigation based on this knowledge, spinneret 1
Pair of discharges = 5 = The holes are connected by a slit, and the discharge hole with a large discharge cross-sectional area is made into a hollow discharge hole forming a hollow part of the plurality of sleeves 1 to 1, and the other discharge hole with a small discharge cross-sectional area is By ejecting pairs of polymer streams with different flow velocities from a spinneret with a single discharge hole, and causing them to collide and bounce, flat sheets with uneven thickness in the longitudinal direction and orientation differences in the cross-sectional direction are produced. A hollow filament 1- is obtained, and a multifilament consisting of such filament 1 is formed between the filaments and between the filaments 1-
The material has a large difference in shrinkage rate within the hem, and by heating it during suction and injection with an air aspirator installed under the mouthpiece, crimp easily develops, resulting in an extremely bulky product. It was discovered that a long-fiber nonwoven fabric can be obtained, leading to the present invention.

That is, according to the present invention, a melt spinnable medium.

- In a long-fiber nonwoven fabric composed of multifilaments 1 made of a polymer, the filaments I constituting the multifilaments are flat and facing each other across the long axis at the outer periphery in 5 directions. an eccentric hollow filament having a pair of concave portions, and having a cross-sectional shape that is asymmetrical with respect to the short axis between the concave portions in the row, and uneven thickness in the longitudinal direction of the filament. and the hollow portion is on the side where the straight line parallel to the short axis is maximum in the cross section of the ficimen 1, and the degree of orientation of the hollow portion existing portion divided by the short axis is a solid adjacent thereto. A bulky long-fiber nonwoven fabric is provided, which is characterized in that the multifilament has a degree of orientation greater than that of the parts thereof, and that the multifilament is crimped by heat treatment at 150 to 450°C.

The present invention will be explained with reference to the drawings.

FIG. 1 is a cross-sectional view of a filament constituting a multifilament used in the present invention, and FIG. 2 is a side view in the longitudinal direction of the filament constituting the multifilament 1 to 1, and a front view obtained by rotating the side view by 90 degrees. Figure 3 is a sectional view of the multifilament I used in the present invention, Figure 4 is a sectional view of the discharge hole of the spinneret for obtaining the above filament, and Figure 5 is the discharge hole shown in Figure 4(a). A perspective view (electron micrograph) of a filament cut along a cross section of the filament immediately after the polymer is discharged from the hole in a free fall manner is shown.

In FIG. 1, ri is the major axis, C is the minor axis, and X.

X' is a pair of recesses facing each other across the long axis (r), e is the hollow part, m is the cross section of ficimen 1 and the short axis ((
), g is the length of the straight line that shows the maximum value among the straight lines parallel to The cross-sectional area of the g section is always larger than that of the 11 section.

In the multifilament 1 used in the present invention, the cross-sectional shape of the constituent filaments is shown in Fig. 1(a) (
As shown in b), it is flat and asymmetrical with respect to the short axis (C) formed by connecting a pair of recesses (x, x') facing each other across the long axis (r), and g part,
That is, a hollow portion (e>) exists on the side having the maximum linear length (rn).

The orientation degree of the g part of the fissuring 1i plane having the cross-sectional shape is higher than the orientation degree of the 71 part, and
The filament 1 has uneven thickness in the longitudinal direction as shown in FIG.

FIGS. 2(a) and 2(b) respectively show a side view of the filament constituting the multifilament and a front view obtained by rotating the side view by 90 degrees.

The thickness unevenness in the longitudinal direction of the filament 1- constituting the multifilamen 1- is as shown in Fig. 2 (a) (+)).
In the longitudinal direction, the cross-sectional area of the h portion changes more widely than the cross-sectional area of the g portion. As shown in Figure 1, if the cross-sectional area of the g part including the hollow part is larger than the h part, the g
The degree of orientation of the part h is higher than that of the part h, and as will be described later, the degree of orientation is much higher than that of the case where the part g is solid because it is subjected to large shearing force during spinning. Together, they can have a large contractile force.

As a result, the long fiber nonwoven fabric of the present invention using such multifilament 1 can exhibit uniform and sufficient bulkiness.

In the present invention, preferred embodiments of the cross-sectional shape of the ficimen 1 include those exhibiting a substantially eyebrow shape as shown in FIG. 1(a), or substantially isosceles triangles as shown in FIG. 1(b). Preferably. In particular, it is preferable to use a polyester resin having a substantially isosceles diagonal cross-sectional shape because it can exhibit a unique luster.

The hollowness ratio of the part g in such a flat hollow filament is 2 to 30%, particularly preferably 15% to 5%, and the sectional rffi product Sg including the hollow part (e) of the part g
and the cross-sectional area Sl′l of the h portion < S g / S
h) is preferably 1.2.about.3, sometimes 1.3 to 1.8.

However, 1. , the hollowness ratio and cross-sectional area Sg and 51-1 are obtained from a condylar microscope photograph of the cross-section of the polygon.

In addition, as shown in FIGS. 2(a) and (b), filament 1
Filament I~, in which the portion h is joined to the portion g without being wrapped in the longitudinal direction of ~, is preferable because its degree of deformation in the longitudinal direction, that is, the thickness unevenness is large.

Naturally, the multifilament according to the present invention, which is constructed of filaments having large thickness unevenness in the longitudinal direction, also has large thickness unevenness in the longitudinal direction.

In addition, in the longitudinal direction of the filaments constituting the multifilament used in the present invention, large thickness irregularities [the length (L) from peak to peak is 0.5 to 3 m] as shown in Figure 2 are randomly present. Therefore, in any cross section of a multifilament made of such filaments, as shown in FIG. 3, an effect similar to that of a mixture of filaments having different deniers is exhibited.

In other words, in Fig. 3, A indicates the filament cross section which is the maximum cross-sectional area of one multifilament cross section,
nl and m indicate the maximum linear length parallel to the long axis and short axis of the filament cross section <A), respectively. In addition, B indicates the filament cross section with the minimum cross-sectional area in one multifilament cross section shown in Figure 3, and n2 and m2 indicate the maximum linear length parallel to the long axis and short axis of the filament cross section (B), respectively. .

In general, when filaments with different cross-sectional areas as shown in Figure 3, i.e., fissiments with different deniers, are mixed, a thick denier filament with a large cross-sectional area is mixed with a thin denier filament with a small cross-sectional area. Since thick denier filaments have a higher shrinkage rate than those of conventional denier filaments, the thick denier filaments shrink more when subjected to heat treatment, resulting in a difference in thread length and can be made into a bulky nonwoven fabric.

The multifilament of the present invention can exhibit a bulky and soft touch texture when the filament (A) with the maximum cross-sectional area and the filament (B) with the minimum cross-sectional area satisfy the following [Formula II]. It is possible and preferable.

rl, x Xmt /n,, Xm2≧1.5 [
Furthermore, as mentioned above, there are large irregularities in the cross-sectional direction and longitudinal direction, that is, there are large differences in shrinkage, so the structure appears to be a mixture of filaments with shrinkage differences between and within the filaments. There is.

Multifi used in the present invention described above = 12
- The laments can be obtained by spinning using a spinneret with discharge holes as shown in FIG.

In FIG. 4]. a to lc, 2.3 are discharge holes for discharging the polymer flow, 4 is a hollow portion formed by a plurality of slots 71 shown as ]a to IC, 2 is a single discharge hole, 3 ]a~1c A slit connecting the hollow discharge hole consisting of the slit and hollow part (4) with the single discharge hole (2), ρA2 is the inner diameter 1,0 and W of the single discharge hole (2) are the length and width of the slit (3), and JIA and QBl are the outer diameter and inner diameter of the hollow discharge hole in FIG. 6(a), respectively.

The characteristics of such discharge holes are that they have different discharge cross-sectional areas] - As a pair of discharge holes, a hollow discharge hole composed of a plurality of slits (1, 8 to lc) is inserted into the discharge hole having a large discharge cross-sectional area, and the other discharge hole has a large discharge cross-sectional area. This is because a single discharge hole (2) is used for each discharge hole with a small discharge cross-sectional area, and the hollow discharge hole and the single discharge hole (2) are connected by a slit (3).

In the multifilament manufacturing method of the present invention, the polymer flow discharged from the hollow discharge hole of FIG. (2) Colliding the discharged polymer flow,
It is necessary to bond them while bouncing them, then cool and solidify them before taking them off.

By employing such a method for producing a multifilament according to the present invention, it is possible to obtain a cross-sectional shape as shown in Fig. Ficimen I has a much higher degree of orientation than the fruit, and also has uneven thickness in the longitudinal direction.
~ is obtained.

In Fig. 18, a pair of four parts indicated by x and x' correspond to the polymer flow discharged from the hollow discharge hole in Fig. 4, and the polymer flow discharged to the discharge hole (2). This is the joined joint.

The reason why such a filament is obtained in the present invention is considered to be as follows.

That is, in general, if the flow velocity of the polymer flow passing through each slit constituting the hollow discharge hole and a single discharge hole is equal to each other, the total pressure loss of the multiple slits of the hollow discharge hole is equal to that of the single discharge hole. It is larger than the hole.

However, a fourth hollow discharge hole and a single discharge hole (2) are combined in the same discharge hole through a slit (3).
In the discharge holes shown in the figure, a flow velocity difference occurs between the polymer flows passing through both holes so that the pressure loss in both holes is equal.

This lick, slit width of hollow discharge hole, single discharge hole (2)
By adjusting the inner diameter of the hollow discharge hole (ρA2) etc., a flow velocity difference is given so that the flow velocity of the polymer flow discharged from the single discharge hole (2) is faster than that of the slits 1a to 1c of the hollow discharge hole. , the difference in flow velocity can be easily increased.

In this way, the flow rate of the polymer flow passing through the slit (la~IC) of the hollow discharge hole is slower than that of the polymer flow passing through the single discharge hole (2), and the spinning draft is caused by the slit (la~IC) of the hollow discharge hole. It is mainly concentrated in the polymer stream discharged from la-lc). Moreover, the filament discharged from the nozzle is suctioned by an air aspirator, but especially at a take-up speed of 25
In high-speed withdrawal of 00 m/min or more, a high draft of 500 or more concentrates on the polymer flow discharged from the slits (la to lc) of the hollow discharge hole, so the hollow portion formed by such a polymer flow is The polymer stream is subjected to a greater shear force than if it were a single discharge hole, resulting in a much higher degree of orientation than if the polymer stream were solid.

The discharge cross-sectional area (S2) of the single discharge hole (2) is the total discharge cross-sectional area (Sl) of the slits (la to lc) of the hollow discharge hole.
>, the cross-sectional area on the h side is smaller than the cross-sectional area on the g side including the hollow part.

In the cross-section of the filament obtained in this way, as shown in FIG. 1, the portion g, which includes the hollow portion (e) and has a larger cross-sectional area than the portion h, has a higher degree of orientation than the portion h.

Furthermore, the flow rate of the polymer flow discharged from the hollow discharge hole and the single discharge hole (2) is different, and
= Since the two polymer streams are connected by the polymer stream discharged from (3), the polymer discharged from the single discharge hole (2) is added to the polymer stream discharged from the hollow discharge hole. As a result of the flow colliding and bouncing and joining together, a filament I having uneven thickness in the longitudinal direction as shown in FIG. 2 is obtained.

The arrangement shape of the slits of the hollow discharge hole and the cross-sectional shape of the single discharge hole (2) employed in the present invention are not particularly limited, and may be any shape known in the art such as a triangle, square, or Y-shape. can be used.

Among these, a triangular array not shown in FIG. 1(b) is preferred.

According to the discharge hole shown in FIG. 4(b) using such a triangular hollow discharge hole, a filament having an approximately isosceles triangular cross-sectional shape as shown in FIG. The filament can exhibit a unique luster.

Further, if the slit array shape of the hollow discharge holes and the cross-sectional shape of the single discharge hole are circular as shown in FIG. 4(a), the cross-sectional shape will be approximately cocoon-shaped as shown in FIG. 1(a). Figure 4(a)
The discharge hole is preferred because it is easy to work with.

Furthermore, in FIG. 4, surprisingly, by connecting the single discharge hole (2) and the hollow discharge hole with a single slit (3), the polymer flow discharged from the single discharge hole (2) is Since the polymer flow discharged from the hollow discharge hole collides and bounces on one side of the polymer flow and joins together, the hollow part (g) and the solid part (
A filament I shown in FIG. 2 in which the filaments h) are bonded without twisting is obtained, and a large thickness unevenness can be imparted to the filament in the longitudinal direction.

The shape of the sleeve I-(3+) may be hook-shaped or curved in addition to the linear shape shown in FIG.

The point is that the hollow discharge hole and the single discharge hole (2) are connected by the sleeve I~.

In addition, by setting the length of the slit (3) so that a recess (x, The vibration period due to the collision and bounce of the combined flow of both types discharged from the filament 1 can be made larger, and extremely large unevenness in thickness can be imparted to the obtained filament 1 in the longitudinal direction. As a result, an arbitrary cross-section of a multifilament made of such filaments has a difference in filament cross-sectional area as shown in FIG. 3, and the values of nl, Xm+, /n2Xm2 in this case are 1.5 or more.

In the discharge hole shown in FIG. 4, one single discharge hole (2) is connected to the hollow discharge hole, but a plurality of single discharge holes (2) may be connected.

Further, the shape of the discharge hole shown in FIG. 4 may be changed so that the obtained filament I has a plurality of hollow portions in the cross section. For example, a plurality of hollow portions of the hollow discharge hole may be provided.

The specific dimensions of the ejection holes used in the present invention described above are shown below for the ejection holes shown in FIG. 4(a).

1.5≦81/S2≦15 S□>82>33゜0.04≦ <, OA1 , Q B+, )/2
≦0.30 -0.10≦! J A2 <, Q
B Go <, QA Go ≦1.50.05≦, Q≦
1.30 0.03≦WρA2≦1.0 However, Sl: Discharge January i area of hollow discharge hole (mrl1
2) S2: Discharge cross section pi (mm”) of single discharge hole (2)
S3: Discharge 1 new ifi product (body 2) of the slit connecting the hollow discharge hole and the ejection hole (2), QAt: Outer diameter of the hollow discharge hole (mm), QB,: Hollow discharge Inner diameter of hole (m[I+), QA2
: Inner diameter of the single discharge hole (2) (mm), Q : Length of the connecting slit 1 (mm) W : Width to the continuous slit (mm), and spinning consisting of such a discharge hole ``By using 1 gold, it is possible to easily obtain a multifilament in which different denier filaments 1~ are mixed together.

Furthermore, in the method for producing a multifilament according to the present invention, the flow rate of the polymer flow discharged from the hollow discharge hole is V;
) and the flow rate (■2) of the polymer stream discharged from a single discharge hole (2), the discharge speed ratio (V1/■2) is 1. /7～
1. /1.5, particularly preferably 1-/3, 4 to 1/2.3, at which time the polymer discharge rate ratio [discharge rate of hollow discharge hole <Ql)/single discharge hole ( 2) Discharge amount (
Q, >] is 3/1- to]15, especially 1.5/:l-
It is preferable to set it to 1./3.3.

Now, with the discharge hole shown in FIG. 4(a), the shape of the spun filament 1 obtained just below the metal surface is Not shown in Figure 5.

Figure 5 shows the result of free fall, and shows that the cross-sectional area on the side discharged from the hollow discharge hole hardly changes, while the cross-sectional area on the side discharged from the single discharge hole changes. It shows. Furthermore, Figure 5 also shows that the polymer flow discharged from a single discharge hole does not wrap around or wrap around the polymer flow discharged from a hollow discharge hole, and vibrates in one direction. . .

However, since the spun filament 1-, which is not shown in FIG. 5, is obtained by free-falling and is not affected by the spinning draft, the cross-sectional shape of the filament 1- constituting the multifilament according to the present invention is different from the one shown in FIG. The difference is -2] - Although it is recognized that under the action of spinning draft, the solid part bounces and joins the hollow part, so the length of the solid part becomes longer than the hollow part, so the length of the solid part is longer than that of the hollow part. A filament having the filament cross-sectional shape shown in (a) is particularly preferred)
It is something that can be done.

The filament I discharged as described above travels through the air and is sucked into an air aspirator installed at a position 20cl11 or 200cm below the nozzle and is ejected. At that time, the take-up speed can be changed by adjusting the suction speed of the air aspirator.
It is preferable to collect the filament at a rate of 00 m/min in order to make the degree of orientation on the g side greater than that on the 11 side in the cross section of the filament shown in FIG.

Here, if the spinning take-off speed is less than 2,500 m for 7 minutes, although thickness unevenness exists in the longitudinal direction of the obtained filaments 1 to 1, the difference in orientation degree in the cross-sectional direction of filaments 1 to 1 tends to be insufficient. There is.

The cross-sectional shape of each filament 7 in an arbitrary cross section of the multifilament f′: ) obtained in this way is as shown in FIG. Also, there is a filament having a shape without recesses (x, x') in the cross section of the filament shown in FIG. Even if filaments with such a cross-sectional shape are present, the object of the present invention can be fully achieved if the number of filaments is small.

In particular, the so-called spinning running zone heating method, in which the polymer flow discharged from the spinning Ll gold is cooled and solidified, further heated under a constant tension, and then taken off, is carried out at a take-up speed of 3000 to 5500.
A latent crimped multifilament having physical properties comparable to drawn yarn (unlike the hot-pressure air drawing described later, no crimps have developed) is obtained in one step by drawing at a speed of 3.0 m/min. This is the preferred method because it allows Heating in this method involves placing the cooled and solidified multifilament at a position of 50-300cn+ from the lower end of the cooling area and heating it over a length of 50 to 100 cm.
This can be achieved by running in a heated atmosphere maintained at 0°C or higher, preferably 200-350'C. As a means for forming such a heated atmosphere, any method such as a heating tube method using an electric heater or the like, a steam jet method blowing heated steam, etc. can be adopted.

In the present invention, the filament is then heated by suctioning with an air aspirator and increasing the temperature of the air. By such heating, crimps and yarn length differences, which had not been latent until then, surprisingly appear all at once, and a nonwoven fabric with excellent bulk when accumulated on a wire mesh can be obtained. 1 The preferable temperature of the air is 150°C or higher and 450°C or higher, particularly 200°C or higher and 300°C or higher.
A range below ℃ is desirable.

If the air temperature is less than 150°C, crimp and thread difference will not be sufficiently developed, and the adhesive treatment that is commonly performed after collecting the filament will not cause crimp or thread difference. 3. Because the thread difference is restricted, the performance cannot be fully demonstrated, resulting in a nonwoven fabric with insufficient bulk.3. On the other hand, in the case of mature jets with air temperatures exceeding 450°C, crimp and yarn length differences are sufficiently developed, but when the fibers come into contact with the aspirator, some of the fibers melt and become hard bolls. There is a tendency for this to occur and lower the quality of the nonwoven fabric.

= 24- Note that the melt-spun homopolymer targeted in the present invention is polyethylene derephthalate-1, in which 85 mol% or more of the repeating units are substantially composed of ethylene terephthalate; In the combination, additives for matting, improving dyeability, antistatic properties, etc. may be included as a copolymer or a blend. The intrinsic viscosity of polyethylene terephthalate (measured in orthochlorophenol at 35°C) is preferably 0.45 to 1.20, particularly 0.45 to 1.20.
50 to 1.00 is preferable. When the intrinsic viscosity is less than 0.45, the strength level of the obtained multifilament tends to be low, and when the intrinsic viscosity exceeds 1.20, the melt viscosity during spinning is too high and the melt temperature is raised. Thermal decomposition during spinning tends to increase.

Effect> When melt spinning the multifilaments 1 to 1 used in the present invention, spinning LI gold having discharge holes as shown in FIG. As a result, large thickness irregularities in the longitudinal direction of the filament, as shown in Fig. 1, can be produced. As shown in the filament cross section,
A multifilament I can be obtained which has both a difference in the degree of orientation in the cross-sectional direction such that the degree of orientation on the g side is higher than that on the Fl side.

By adjusting the slits 1-riJ of the plurality of slits constituting the hollow discharge hole and the hole diameter of the single discharge hole, the flow velocity difference between the polymer streams discharged from the pair of such discharge holes can be made sufficiently large. can do.

This slick allows the spinning draft to be concentrated on the polymer flow discharged from the hollow discharge hole, and a large shearing force acts on the polymer flow discharged from the hollow discharge hole, so that the degree of orientation in the hollow portion is reduced to that of the solid portion. higher than the orientation degree of r-
It is possible to achieve an extremely higher degree of orientation than when the 1-+ hollow portion is solid.

Moreover, since the total discharge cross-sectional area to the plurality of ribs 1 constituting the hollow discharge hole is larger than the discharge cross-sectional area of a single discharge hole,
In the cross section to the obtained fissine>.1, the cross-sectional area of the hollow part is larger than that of the solid part.

Further, even if the distance between the two holes is increased, since the two holes are connected by the slit, the two types of combined flow can be joined while generating large vibrations due to collision and bounce.

The filaments constituting the multifilament obtained in this way have an extremely high degree of orientation in the hollow part, which has a larger cross-sectional area than the solid part. In addition to having a shrinkage rate, the filaments also have large thickness variations in the longitudinal direction, so multifilaments made of such filaments have large shrinkage differences between and within the filaments, and when heated air It can exhibit a large shrinkage force during heat treatment.

(Effects of the Invention) The present invention can improve the conventional long-fiber nonwoven fabric spinning apparatus ( By using the spunbond method as is, a long-fiber nonwoven fabric with excellent bulkiness can be obtained.Therefore, there is no need for expensive and complicated equipment such as a conjugate spinning machine, resulting in lower costs and maintenance. It is now possible to make fabrics of the same level as conventional long-fiber nonwoven fabrics, and the economic effect is significant.In addition, since it also has the toughness of long-fiber nonwoven fabrics, its usefulness has greatly improved, and it has been widely used in the medical and hygiene fields. It can be used in a wide range of fields, including general household supplies, clothing materials, and agricultural and engineering wood materials.

(Example) Hereinafter, the present invention will be further explained with reference to Examples. In addition, each characteristic used in the examples was measured by the following method.

(1) n1m, 02m2: Take a cross-sectional photograph of any cross-section of the multifilament ejected into the air aspirator at a magnification of 560 times, and determine the long axis and short axis of the filament cross-section where the cross-sectional area including the hollow part is maximum. The maximum straight line length (m, ) in the direction parallel to , and the long axis of the filament cross section (n2
) and the maximum straight line length m2) in the direction parallel to the short axis.

(2) 11 dimensions: Cut out a 20 x 20 cm sample of the bonded nonwoven fabric to which an adhesive has been applied, measure its weight, repeat 10 times, and determine the basis weight from the average weight.

(3) Thickness: Size 20X20an, weight 0.25g/cIi<10
0 g > of the resin plate, then place the resin plate on the nonwoven fabric, measure the thickness, and calculate the thickness of the nonwoven fabric from the difference. Repeat 10 times and take the average value as the thickness.

(4) Bulky: Calculated from the basis weight and thickness.

(5) Texture: In addition to classifying the texture from soft to soft texture to hard paper-like texture, the fiber shape (particularly the presence or absence of hardness due to melting) is determined by microscopic observation. .

Example 2: Polyethylene terephthalate (containing 0.3% by weight of TiO2 as a matting agent) having an intrinsic viscosity [η] of 0.64 was melted and then heated to 300°C, as shown in Figure 4a. It was discharged from the discharge holes at a discharge rate of 1.0 g/min per hole (250 discharge holes).

Table 1 shows the dimensions of each part of the discharge hole used here.

-30= Note that the land lengths of the hollow discharge hole, single discharge hole 2, and slit 3 shown in Table 1 are all 0.6+nm.

In such a discharge hole, the discharge amount ratio <Q1/Q2) and the discharge speed ratio (V
l/V2) were 1.2/1 and 1/3.4, respectively.

Then, the polymer flow discharged from the single discharge hole 2 collides and bounces onto one side of the polymer flow discharged from the hollow discharge hole directly below the spinneret.

The unbonded PET stream was then heated to a temperature of 26°C and a humidity of 60°C.
% cooling air was blown at a linear velocity of 30 an/sec to cool and solidify, then the mixture was sucked and jetted at a velocity of 3,500 m/min by an air aspirator, and collected on a wire mesh.

Further, an acrylic acid ester emulsion adhesive was applied to the thus assembled web, which was dried and rolled up. The filaments constituting the long fiber nonwoven fabric produced in this way have the cross-sectional shape shown in FIG.
The hollow ratio of the part was 8%.

In addition, the ratio of the maximum and minimum cross-sectional areas of the multifilament injected from the air aspirator in any cross section (rz
2 > + A cross-sectional area Sg including the hollow part e of the g part,
Table 2 shows the ratio S g/Sh to the cross-sectional area sh of the h portion.

Table 2 In addition, Table 3 shows the bulkiness and texture of the obtained long fiber nonwoven fabric when the temperature of the compressed air supplied to the air aspirator was changed.

Comparative Example 1 - PET with an intrinsic viscosity [η] of 0.64 (Ti as a quenching agent)
(contains 0.3% by weight of O2) tends to melt at '100'C
Heat the hole to
) and was discharged at a discharge rate of 1.0 g/min. (Number of discharge holes: 250) Next, cooling air at a temperature of 26°C and a humidity of 60% was blown onto the PF and T streams at a linear velocity of 30 cm/sec, and after cooling and assimilation, the air aspirator was used to blow the cooling air at a speed of 3500 m/min. Do not aspirate, spray, or collect on wire mesh. Furthermore, an acrylic acid ester emulsion adhesive was applied to the thus obtained web, which was dried and rolled up. Table 4 shows the temperature of the air used in the aspirator and the bulkiness and texture of the nonwoven fabric.

= 35 -

[Brief explanation of drawings]

FIG. 12 is a sectional view of filaments 1 to 1 constituting the long fiber nonwoven fabric of the present invention, and FIG. 2 is a side view of the filaments in the longitudinal direction and 90
°Rotated front view. FIG. 3 is a cross-sectional view of a group of filaments constituting the long-fiber nonwoven fabric of the present invention, FIG. 4 is a cross-sectional view of the discharge hole of a spinneret for obtaining the long-fiber nonwoven fabric of the present invention, and FIG. Immediately after the polymer is discharged in free fall from the discharge hole shown, filaments 1 to 1 are cut along the cross section and perspective views (electron micrographs) of the filaments are shown.

Claims (6)

[Claims] 1. In a long-fiber nonwoven fabric composed of multifilaments made of a single polymer that can be melt-spun, the filaments constituting the multifilaments are flat and facing each other across the long axis at the outer periphery in the long axis direction. An eccentric hollow filament having a pair of recesses, a cross-sectional shape that is asymmetric with respect to the short axis between the pair of recesses, and uneven thickness in the longitudinal direction of the filament, The hollow portion is on the side where the straight line parallel to the short axis is maximum in the cross section of the filament, and the degree of orientation of the hollow portion existing portion divided by the short axis is higher than the degree of orientation of the adjacent solid portion. 1. A bulky long fiber nonwoven fabric characterized in that the multifilaments have large fibers and are crimped by heat treatment at 150 to 450°C. 2. The bulky long fiber nonwoven fabric according to claim 1, wherein the filament has a cross-sectional shape that is substantially cocoon-shaped and asymmetrical with respect to its short axis. 3. The cross-sectional shape of the filament is approximately isosceles triangular and has a pair of recesses on opposing long sides, and
The bulky long fiber nonwoven fabric according to claim 1, which is asymmetrical with respect to the short axis between the pair of recesses. 4. The bulky long fiber nonwoven fabric according to claim 1, wherein a plurality of hollow filament portions are present. 5. 2. The bulky long fiber nonwoven fabric according to claim 1, wherein the solid portion is bonded to the hollow portion without being wound around the hollow portion in the longitudinal direction of the filament. 6. The bulky long fiber nonwoven fabric according to claim 1, wherein the filaments in any cross section of the multifilament satisfy the following formula [I]. n_1×m_1/n_2×m_2≧1.5 [I] However, n_1×m_1, n_2×m_2 is the maximum linear length parallel to the major axis and short axis for each filament cross section in an arbitrary cross section of the multifilament. The product is
The maximum and minimum values are shown respectively.