JPH01148862A - Bulky spun bond nonwoven fabric made of crystalline thermoplastic resin - Google Patents

Abstract

PURPOSE: To obtain the subject non-woven fabric having stable bulkiness and flexibility by using filaments, each having a modified cross section, having loop portions whose crimped spiral diameter is a specific value or smaller, and twisted and three-dimensionally disposed in the non-woven fabric, as filaments constituting the non-woven fabric. CONSTITUTION: This bulky spun-bonded non-woven fabric is produced from a crystalline thermoplastic resin such as polypropylene. Therein, each of filaments constituting the non-woven fabric has a modified cross section such as a triangular cross section, and a loop portion crimped spiral diameter of <=1 mm, preferably 1.0-3.0 mm. The filaments are twisted and three- dimensionally disposed in the non-woven fabric, and preferably have one or more filament twists in a filament length of 15 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spunbond nonwoven fabric made of polypropylene long fibers. More specifically, the present invention relates to a polypropylene long fiber spunbond nonwoven fabric whose constituent filaments have a specific cross-sectional shape and are arranged in a specific shape in the nonwoven fabric, thereby making it bulky and flexible.

(Problems to be solved by the prior art and the invention) Currently, spunbond nonwoven fabrics are used for various purposes.In particular, polypropylene spunbond nonwoven fabrics are used as top sheets for disposable diapers by utilizing the flexibility of polypropylene fibers. However, since the filaments used in these spunbond nonwoven fabrics are non-crimped, the resulting nonwoven fabrics have poor bulk and flexibility. However, as its use in diaper top sheets and the like has become widespread, there has been an increasing demand for bulky and flexible spunpond nonwoven fabrics.

The bulky and flexible nonwoven fabric itself can generally be made by forming a web of crimped short fibers (for example, Nisso ES fiber) using a card type web making machine and then using a hot air bonding method. However, since they are short fibers, they have drawbacks such as poor fabric strength and short fibers falling off due to damage to the bonding portion.

Therefore, the spunpond nonwoven fabric, which is made by directly forming a long fiber web without passing through short fibers, has physical properties such as strong fabric strength and no fibers falling off due to damage to the bonding part. It has many advantages compared to card-type staple fiber nonwoven fabrics, such as lower production costs due to shorter processes.

Therefore, various manufacturing methods have been proposed to provide bulky long fiber nonwoven fabrics.

For example, Japanese Patent Publication No. Sho 62-1026 describes an ejection hole for ejecting a fiber-forming fluid together with a pressurized fluid, a crimp section consisting of a ventilation wall provided at the tip of the ejection hole, and a section around the crimp section that is A pressurizing chamber for creating a pressurized atmosphere, and an ejection hole provided at a position opposite to the crimping section to eject the crimped yarn while opening and unraveling the crimped long fiber nonwoven fabric. A manufacturing apparatus is disclosed. By using this device, a long fiber nonwoven fabric consisting of substantially opened long fibers having a number of crimps of 5 to 25 crimps/25 mm and a degree of crimp of 2 to 30% by buckling crimp can be obtained. It is said that it will be done.

However, since the long fiber nonwoven fabric disclosed in Japanese Patent Publication No. 62-1026 is a buckling crimped yarn, the buckling direction in the direction along the surface of the nonwoven fabric does not contribute to bulkiness. In order to develop sufficient bulkiness, it is necessary to increase the number of crimps excessively, and as a result, the basis weight becomes large and sufficient bulkiness cannot be provided.

Furthermore, JP-A-48-1471 discloses that after spinning, two types of polymer compositions having different shrinkage properties are composite-spun into a bimetal type or eccentric sheath-core type, or a polymer composition is spun. After spinning, the filament is spun to have a biased temperature gradient within its cross section, and the substantially stretched continuous filament obtained by continuous high-speed drawing is drawn onto the collection surface by the action of a high-speed airflow guided from the outside. The collected material is deposited on the collection surface by heating or solvent treatment in a state where the number of crimps is at least 5/inch or more and the crimp elasticity is 2% or more and is deposited on the collection surface, and if necessary, turbulence treatment is also performed. A method is disclosed for forming a mat-like web in which continuous filaments are arranged in random loops.

The fibers in the structure disclosed in Japanese Unexamined Patent Publication No. 1471/1971 are formed by a fiber having a normal circular cross section in a helical crimped structure, and therefore, during use, the entanglement of the helical crimps does not occur. It has the problem that it is strengthened and its bulkiness decreases. Furthermore, this publication does not disclose the idea of twisting the constituting filaments or reversing the direction of the crimped helix. Furthermore, Japanese Patent Application Publication No. 48-1471
The bulky cloak-like fiber structure disclosed in the publication is intended for futon cotton, etc. having a thickness of 20 to 400 U+, and is applicable to thin and bulky spunbond fabrics such as top sheets as in the present invention. The target area is different from that of

In addition, the Fiber Science Society Journal (Collection of Papers) Vol.
, 29, No. 4 (1976) T 57
-62 disclose polypropylene crimped fibers produced by an asymmetric cooling method. In order to obtain this polypropylene crimped fiber, performing asymmetric cooling immediately after spinning to bring the density distribution in the undrawn fiber to a certain suitable range is said to be the basic condition for imparting crimp ability to the undrawn fiber. This undrawn yarn is stretched and then subjected to a relaxation heat treatment to obtain a crimped drawn yarn. Therefore, the manufacturing process is long and requires large-scale manufacturing equipment, and it is not suitable as a method for obtaining long fiber spunbond nonwoven fabrics that need to be manufactured in large quantities and at low cost. In addition, the obtained crimped and drawn yarn always has the same side of the T half cross section facing the inside of the spiral, so even if a large number of crimped and stretchable yarns are collected and made into a web, sufficient bulkiness can be expected. I can't.

An object of the present invention is to solve the problems of the conventionally known spunbond nonwoven fabrics mentioned above, and to provide a spunbond nonwoven fabric that has stable bulkiness and flexibility.

[Means for solving problems]

The above-mentioned object of the present invention is to provide a spunbond nonwoven fabric made of a crystalline thermoplastic resin, in which the filaments constituting the nonwoven fabric have an irregular cross section and a crimped helix diameter of 1 to 1.
This is achieved by a bulky crystalline thermoplastic resin spunbond nonwoven fabric having the following loop portions and being twisted and three-dimensionally arranged in the nonwoven fabric.

As the crystalline thermoplastic resin, polypropylene, polyethylene, polyester, etc. can be used. In particular, it is more preferable to use polypropylene in order to form a loop portion in the filament with a crimp spiral diameter of 1 cm or less.

As the irregular cross-section, polygonal cross-sections such as triangular cross-sections, various cross-sectional shapes such as C-shaped cross-sections, etc. can be used.

However, in order to obtain bulkiness and flexibility, it is preferable to use an irregular cross-section yarn having a cross-sectional shape with protruding parts than a solid irregular cross-section yarn. For example, in the case of a thread with an irregular cross-section having a triangular cross section, the cross-sectional shape is a triangular cross section with three protrusions outside the center, the width of the bottom of the protrusions is t, and the length of the protrusions is 1, and the cross-sectional area of the fiber is S, most of the constituent filaments have a cross-sectional shape that satisfies the following conditions, and the average value of the interval at which twist occurs in the longitudinal direction of the filaments is 5 to 15 m1. and preferable.

The diameter of the crimped helix of the loop portion of the filament constituting the spunbond nonwoven fabric according to the present invention is preferably 1 mm or less, more preferably 1.0 to 0.3 fi. If the crimped helix diameter exceeds 1.0 mm, the number of crimps per unit length will be small, resulting in poor bulkiness, and if it is less than 0.3 R, the space obtained by the helical shape will be extremely small. The bulkiness deteriorates and the entanglement between the filaments becomes too strong, which tends to cause myositis during web production.

It is preferable that the filaments in the nonwoven fabric have one or more twists within the length of the filaments.

Various finenesses of filaments constituting the spunbond nonwoven fabric according to the present invention can be used. However, since the non-woven fabric according to the present invention is mainly used as a thin bulky non-woven fabric, in that case, the non-woven fabric is 0.5 d to 5 d. Od filaments are preferably used.

The basis weight of the spunbond nonwoven fabric according to the present invention varies depending on the intended use. For example, thin nonwoven fabrics such as diaper top sheets weigh 15 to 30 g in terms of required properties and economy.
It is best to use one with a basis weight of / rtr.

The spunbond nonwoven fabric according to the present invention has bulkiness as described above. In the present invention, the loftiness is expressed as the bulkiness factor H, which is the value obtained by dividing the thickness (μ) at the time of 10 g/4-load by the basis weight (g/rd), and it is preferable that the value of H is 20 or more.

-a, if the bulkiness of the nonwoven fabric is improved, the nonwoven fabric will be easier to stretch in the warp direction or the weft direction. Especially when it becomes easier to stretch in the warp direction, the nonwoven fabric will stretch in the warp direction during the processing process to make certain products.
It has the disadvantage that the width in the latitudinal direction becomes narrower as the width increases. The spunbond nonwoven fabric according to the present invention has a 5% modulus in the longitudinal direction of 20 g/rd and 0.4 in order to prevent the above-mentioned defects even though it is bulky.
kg/3cm width or more. In order to obtain a nonwoven fabric with a modulus of 5% of this value, it is recommended to add appropriate tensile effects to the web manufacturing process and to use partial thermal bonding.

The present invention will be described in detail below with reference to the accompanying drawings showing an example of the spunbond nonwoven fabric of the present invention.

Figure 1 shows the planar direction of the nonwoven fabric of the present invention (Figure 1A) -
and an electron micrograph (magnification 4) in the thickness direction (Fig. 1B).
0 times). From these photographs, it can be observed that the filaments constituting the nonwoven fabric of the present invention have an irregular cross section, a loop portion with a crimped helix diameter of 1 crane or less, and are twisted and arranged three-dimensionally in the nonwoven fabric. Can be done.

Fig. 2 shows the planar direction of a conventionally known long fiber nonwoven fabric (Fig. 2A
) and in the thickness direction (Figure 2B). As shown in these photographs, in conventionally known long fiber nonwoven fabrics, the filaments constituting the nonwoven fabric are not crimped; They are arranged in a straight line and lack bulk.

As can be easily seen by comparing FIG. 1B and FIG. 2B, the conventional long-fiber nonwoven fabric is thinner than the nonwoven fabric of the present invention, which indicates a difference in bulk.

FIG. 3 is a microscopic photograph of filaments taken out from a web of the nonwoven fabric of the present invention before compression treatment, and the spiral crimp of the filaments constituting the nonwoven fabric of the present invention can be observed as loops. On the other hand, filaments constituting conventionally known nonwoven fabrics have a linear shape or shape as shown in FIG.

The mechanism by which the filaments constituting the nonwoven fabric of the present invention are twisted will be explained based on FIG. In producing the nonwoven fabric of the present invention, in addition to the first cooling device for cooling the asymmetrically spun filaments as described below, a second cooling device is used to give twist to the filaments. The state of the filament at this time is shown in FIG. 5A. In other words, the upstream vertices a, b, and c of the triangular cross section are a', b' at the downstream.
.

It is twisted as shown by a'. In this twisted state, cooling air is applied from the first cooling device, so the cooling air side, that is, the front side in FIG. 5A, is cooled and solidified first to form a low-density portion. When the filament is spun and taken off, as shown in FIG. 5B, each of the upstream vertices a and b of the triangular cross section.

C and the downstream vertices a#, bL, and cJ return to positions corresponding to each other, and the low-density portions are arranged to overlap with each other.

Therefore, as illustrated in FIG. 6, in the filament constituting the nonwoven fabric of the present invention, one component (shaded area) is exposed and hidden four times for every 2.5 crimps in the figure.

On the other hand, as shown in FIG. 7, in the conventionally known spiral crimp of untwisted filaments in long-fiber nonwoven fabrics, the number of times of helical crimp is the same as the number of times that one component is hidden. That is, one component, such as a low-density section, arranged on the outside of the helical shape is always on the outside in the longitudinal direction of the filament.

FIG. 8 illustrates the cross-sectional shape of filaments constituting the nonwoven fabric of the present invention. Any of the irregular cross-section filaments has a cross-sectional shape with a protrusion.

When the cross-sectional shape of the filament constituting the nonwoven fabric of the present invention is triangular, it is preferable that the values of t and l as defined in FIG. 9 satisfy the specified values as described above. In other words, t is the width of the protrusion at the position where the inscribed circle of the irregular cross section touches (root of the protrusion), and l is the position where the inscribed circle touches (
Measure the length from the base of the protrusion to the tip of the protrusion.

Next, a method for manufacturing the bulky crystalline thermoplastic resin spunbond nonwoven fabric of the present invention will be explained with reference to FIG. 10. The spunbond nonwoven fabric of the present invention is made of polypropylene with a deformed base 1.
The yarn 9 is melt-extruded and immediately below the arrival in Japan, cooling air is blown from a direction perpendicular to the running direction of the yarn 9 under the special conditions described below, and a high-speed air soccer etc. The vehicle will be picked up using a high-speed towing/taking device 4.

The yarn leaving the high-speed traction and take-off device 4 passes through a charging device 5, is collected as a web 10 on a moving wire mesh conveyor 6, is conveyed, and is thermally bonded by a partial thermal bonding roll 7 to form a spunbond nonwoven fabric 11. It is wound up using a winding machine 8.

In the method for producing spunbond nonwoven fabric of the present invention, in addition to the normal cooling air supply device 2 (hereinafter referred to as the first cooling device 2) having its upper end at a position of 10 to 15 cm below the spindle surface, a , 0.5 to 1.5 degrees in a direction different from 5 degrees to 45 degrees in the horizontal plane with respect to normal cooling air discharged in the horizontal direction.
Cooling air supply device 3 (hereinafter referred to as the second
(referred to as a cooling device 3). The cooling air mentioned here has a RH of about 70% and 20° C. at the outlet. The crimped filament of the present invention rotates the irregularly shaped filament around the longitudinal axis of the filament by using another cooling air at a position closer to the spinneret surface than the normal cooling air and at a different angle from the normal cooling air. A force acts, which causes the location that cools and solidifies first to change randomly along the length. As a result, the helical crimped filament itself becomes twisted in the length direction.

When manufacturing a filament having a helical crimp, the windward side of the irregularly shaped filament is first cooled and solidified, and then the leeward side is solidified. By doing this while being pulled at a high speed, the yarn is released from the high speed pulling and is collected as a web on the collection surface, resulting in visible crimp.

Although the windward side cools and solidifies, it is elongated by the traction force of high-speed traction, and in this state, the leeward side cools and solidifies.
It is thought that only the windward side, which had been elongated when released from the traction force, contracts, causing overt crimp. The crimped filament of the present invention has a density of 0.900 or less, whereas conventional non-crimped filaments have a density of more than 0.905, and the density of the part that cools and solidifies first on the windward side is 0.900.
It seems that crystallization of about 805 is extremely suppressed.

As shown in FIG. 6, the filaments constituting the nonwoven fabric of the present invention thus obtained are arranged such that a certain part of the cross section of the filaments is located outside the helix of the filaments, and
It is moved by being placed inside.

〔Example〕

The present invention will be explained in further detail with reference to Examples below.

Prior to the description of Examples, the definitions and measurement methods of physical property values used in the present invention will be summarized below.

■Weight: Expressed in weight (g) per 1rrf of nonwoven fabric.

■Bulk factor (H) Compressive elasticity testing machine manufactured by Nakajiro Denki Sangyo ■ Using the E-2 type, Failure at 10g load under measurement area 4d Measure the thickness T (μ) of the woven fabric and calculate the basis weight. Expressed as the divided value.

H-T/eye (size) Helix diameter: The diameter of the loop is measured under a microscopic photograph of the nonwoven fabric, and the average value (w) is used.

■Width t of protrusion in fiber cross section (μ) At the base of the protrusion in the fiber cross section The average of 10 filaments in the width of the protrusion value.

◎Length l (μ) of protrusions on fiber cross section Protruding from the base of the protrusion in the cross section of the fiber. filament at the distance to the tip of the Average value of 10 pieces.

■Twisting in the longitudinal direction of the filament In electron micrograph, filament The part where the twist is strong (the angle of change is (more than 10°) and the twist is reversed. The length of the filament Express the distance in this part in simple terms. Was.

0M FR: JIS [7210] Measured under condition 4 in Table 1 and represents the ease of flow of the polymer.

■ A nonwoven fabric with a 5% modulus in the vertical direction was cut into a rectangle with a width of 3 as and the tensile direction was in the vertical direction, and a tensile test was performed at a tensile speed of 30 / min using a Tensilon manufactured by Toyo Baldwin ■. Stress is expressed in kg.

O flexibility JIS L1096 stiffness is determined by E method (6,1
Polypropylene (MFR = 38
Measured under condition 4 in JIS K7210 table) at extrusion temperature 2
Extruded quantitatively at 1300 g/m at 40 °C, 15
1 m in the longitudinal direction with 40 holes of irregular triangular cross-section nozzles (arranged in 220 rows in the longitudinal direction and 7 columns in the radial direction at equal intervals)
By using a rectangular spinneret with a width of 5 ca+, a group of irregularly shaped filaments is spun, and this is pulled at a speed of 3500 m/min by using a rectangular high-speed airflow traction device,
After charging with a corona charging device, the web was placed on a wire mesh web conveyor equipped with a moving suction device.

50 CI in the running direction of the filaments for cooling the filament group between the spinneret and the rectangular high-speed air traction device.
a first cooling device 2 and a first cooling device 2 having a length of 11;
A second cooling device 3 with a length of 5 cm is installed closer to the spinneret surface.
was installed, and cooling air (70% R, H, 20° C.) was blown perpendicularly to the strike direction of the filament group. The upper end of the cold air blowing position of the first cooling device 2 is 15 cm from the spinneret surface, and the cooling air speed is 1.0 m/5ecs, and 5c in the second cooling device 3.
m and 0.5 m/see. Also, the blowing direction of cold air from the first cooling device and the second cooling device is 1 in the horizontal plane.
The difference was 0°. The filaments constituting the obtained bulky long fiber web had an average number of crimps of 10/25 mm.

This web was conveyed by a wire mesh conveyor 6 and thermocompression bonded at 135° C. by a partial thermocompression roll 7 to obtain a bulky spunbond nonwoven fabric with a basis weight of 20 g/M. The speeds of the conveyor, partial thermocompression roll, and winding machine at this time were 47 m/min, 49.0 m/min, and 50 m/min, respectively. The embossing roll used for partial thermocompression had a crimping area of 7%, the shortest distance between the crimping points was 1.5 u, and the depth of the embossing engraving was 0.
．． It was 81.

The crimped helix diameter of the filaments in the spunbond nonwoven fabric obtained was 0.8 mm, and the average interval at which twist occurred in the longitudinal direction of the filaments was 10 mm.

The bulk factor (■) was 3o, and the flexibility was 12.0 g in the vertical direction and 4.8 g in the horizontal direction. The 5% modulus in the vertical direction was 0.47 kg/3 cm Width T: t obtained from the cross-sectional photograph of the constituent filaments is 8
．． 5μ, l was 13μ, and the denier of the single yarn was 2.2 denier.

The distance from the spinneret surface to the upper end of the cold air blowing position of the first cooling device 2 and the second cooling device 3 for the yarn is 20 CI, respectively.
8,10 (M!1 and cooling air speed 1.0 m/s in both cases)
A spunbond nonwoven fabric with a basis weight of 20 g/m was obtained under the same conditions as in Example 1 except that ec was used.

The crimped helix diameter of the obtained nonwoven fabric was 0.9 va,
The average value of the intervals at which twist occurred in the longitudinal direction of the constituent filaments was 11 mm. The bulk factor H of nonwoven fabric is 28
The flexibility is 12.3g in the vertical direction.

It weighed 5.0 g in the horizontal direction. The cross-sectional shape of the filament was trilobal, t was 8.5μ, and l was 12μ.

Spunbond nonwoven fabric with a fabric weight of 1.15 g/rrr was prepared under the same conditions as Example 2, except that the speeds of the Yukon bearer, thermocompression roll, and winding machine were set to 62 m/min, 64 m/min, and 65 m/min, respectively. I got it. The bulk factor of the obtained nonwoven fabric was 31, the flexibility was 8.0 g in the vertical direction, and 4 in the horizontal direction.
．． It was 4g. Vertical 5% modulus is 0.42
kg/3 cm width.

Implementation ■ The amount of soil melt extrusion was set to 1540 g/min, and the speed of the conhair, partial heat compression roll, and crimping machine was set to 55% each.
Example 2 except that m/min, 57m/min, and 58m/min
A nonwoven fabric with a basis weight of 20 g/rtr was obtained under the same conditions as above.

The diameter of the crimped helix of the obtained nonwoven fabric was 0.9 ml, and the interval at which twist occurred in the longitudinal direction of the constituent filaments was 13 times. The bulk factor H of the nonwoven fabric was 29, and the degree of flexibility was 12.6 g in the vertical direction and 5.1 g in the horizontal direction. The cross-sectional shape of the filament is trilobal, and t is 9μ.
l was 12μ.

A spunbond nonwoven fabric was obtained under the same conditions as in Example 1 of the northern group except that a spinning nozzle having a round shape and a short cross-section spinneret was used.

Although there were crimps in the web before thermocompression bonding, the number of crimps was as small as 3/25, and the obtained nonwoven fabric also had a bulk factor H of 16 and lacked bulk.

Indigo 1 A spunbond nonwoven fabric was obtained under the same conditions as in Comparative Example 1 except that the second cooling device 3 was removed.

There was no crimp in the filaments, and the obtained nonwoven fabric lacked bulkiness with a bulkiness factor H of 14.2. (The nonwoven fabric of Comparative Example 2 is a conventional spunbond nonwoven fabric, as shown in the electron micrograph in Figure 2.) The flexibility of the nonwoven fabric is 17.5 g in the vertical direction, 7.5 g in the horizontal direction, and the 5% modulus in the vertical direction is It was 1.3 kg/3 cm width.

Northern Comparison ■ A spunbond nonwoven fabric was obtained under the same conditions as in Main Example 1 except that the second cooling device 3 was removed.

The number of crimps in the filament was 4/25B, the diameter of the crimped helix was 1.5 mm, and no twisting of the filament occurred. The obtained nonwoven fabric has a bulk factor H of 16
It lacked bulk. The flexibility of the nonwoven fabric was 16.8 g in the vertical direction, 7.0 g in the horizontal direction, and the 5% modulus in the vertical direction was 1.2 kg/3 cm width.

〔Effect of the invention〕

Since the nonwoven fabric of the present invention is configured as described above, it has excellent bulkiness and flexibility that cannot be obtained with conventional long fiber nonwoven fabrics.In addition to these excellent properties, long fiber nonwoven fabrics inherently have high strength and In addition to properties such as non-shedding of fibers and low stiffness, it can be usefully used in a wide range of applications such as top sheets of diapers.

[Brief explanation of the drawing]

FIG. 1 is a microscopic photograph showing the shape of the constituent fibers in the nonwoven fabric of the present invention, and FIG. 1A is a photograph taken in the planar direction;
FIG. 1B is a photograph taken in the cross-sectional direction. FIG. 2 is a microscopic photograph showing the shape of the constituent fibers of a conventionally known nonwoven fabric, FIG. 2A is a photograph taken in a plane direction, and FIG. 2B is a photograph taken in a cross-sectional direction. FIG. 3 is a microscopic photograph illustrating the shape of one filament constituting the nonwoven fabric of the present invention, and FIG. 4 is a microscopic photograph illustrating the shape of one filament constituting a conventionally known long fiber nonwoven fabric. be. Fifth
The figures are perspective views illustrating the twisting mechanism of filaments constituting the nonwoven fabric of the present invention, in which Figure 5A shows a state in which the filaments are twisted and cooled asymmetrically immediately after spinning, and Figure 5B shows a state in which the filaments are twisted and cooled asymmetrically. The filament produced in this manner is shown in a state where it is being taken off. FIG. 6 is a diagram schematically showing the shape of filaments constituting the nonwoven fabric of the present invention. FIG. 7 is a diagram schematically showing the shape of filaments in a conventionally known long fiber nonwoven fabric. FIG. 8 is a diagram illustrating the cross-sectional shapes of various filaments constituting the nonwoven fabric of the present invention. FIG. 9 is a diagram illustrating elements that define the cross-sectional shape when the filaments constituting the nonwoven fabric of the present invention have a triangular cross-section. FIG. 10 is a side view showing an example of the nonwoven fabric manufacturing apparatus of the present invention. 1... Base, 2... First cooling device,
3...Third cooling device, 4...High speed traction device 5...Charging device, 6...Wire mesh conveyor,
7... Partial thermal adhesive roll, 8... Winder, 9...
Yarn, 10...Web, 11...Nonwoven fabric, D...Low density part, Shi...Width of the filament at the position where the inscribed circle touches, l...Protrusion from the position where the inscribed circle touches Length to tip.

Claims (2)

[Claims] 1. A spunbond nonwoven fabric made of a crystalline thermoplastic resin, in which the filaments constituting the nonwoven fabric have an irregular cross section and a loop portion with a crimped helix diameter of 1 mm or less, and are arranged three-dimensionally while being twisted in the nonwoven fabric. A spunbond nonwoven fabric made of bulky crystalline thermoplastic resin. 2. When the irregular cross section is a triangular cross section having three protrusions outside the center, the width of the bottom of the protrusions is t, the length of the protrusions is l, and the cross-sectional area of the fiber is s. Most of the constituent filaments have a cross-sectional shape that satisfies the following conditions,
The spunbond nonwoven fabric according to claim 1, wherein the average value of the intervals at which twist occurs in the longitudinal direction of the filaments is 5 mm to 15 mm. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼