JPH0429776B2 - - Google Patents

Description

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

[Problems to be solved by conventional technology and invention]

Currently, spunbond nonwoven fabrics are used for various purposes. Among these, polypropylene spunbond nonwoven fabrics are used for the top sheet (the sheet that contacts the skin) of disposable diapers, etc., taking advantage of the flexibility of polypropylene fibers. However, since the filaments used in these spunbond nonwoven fabrics are non-crimped, the resulting nonwoven fabrics have the problem of poor bulk and insufficient flexibility, making them difficult to use in diaper top sheets, etc. As spunbond nonwoven fabrics become more widespread, there is an increasing demand for bulky and flexible spunbond nonwoven fabrics.

The bulky and flexible nonwoven fabric itself is generally made by creating a web from crimped staple fibers (for example, Chitsuso ES fiber) using a card-type web manufacturing machine.
It can be made by 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 bonding parts.

Therefore, spunbond nonwoven fabrics made by directly forming long fiber webs without passing through short fibers have physical properties such as high fabric strength and no fibers falling off due to breakage of the bonding part. Furthermore, it has many advantages over card-type staple fiber nonwoven fabrics, such as lower production costs due to shorter production steps. 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 pressure fluid, a crimp portion consisting of a ventilation wall provided at the tip of the ejection hole, and a crimp portion that is heated around the crimp portion. A pressurizing chamber for creating a pressurized atmosphere, and an ejection hole provided at a position opposite to the crimping section for ejecting the buckled crimped yarn while opening and unraveling the fibers. 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 crimp degree of 2 to 30% by buckling crimp can be obtained. That's what it means.

However, since the long fiber nonwoven fabric disclosed in Japanese Patent Publication No. 62-1026 is a buckled crimped yarn, the buckling direction is along the surface of the nonwoven fabric.
It does not contribute to bulkiness, and 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.

In addition, JP-A-48-1471 discloses that after spinning, two types of polymer compositions having different contractility are composite-spun into a bimetal type or eccentric sheath-core type, or a polymer composition is spun. A substantially stretched continuous filament obtained by spinning the yarn so that it has a biased temperature gradient within the cross-section of the filament and continuously taking it off at high speed is spun onto the collection surface by the action of a high-speed airflow guided from the outside. The material is transported and 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 performed. A method for forming a mat-like web in which continuous filaments are arranged in a random loop shape is disclosed.

However, the bulky mat-like fiber structure disclosed in JP-A No. 48-1471 is intended for futon cotton, etc. having a thickness of 20 mm to 400 mm, and as in the present invention, it is intended for use with low basis weights such as top sheets. It does not have sufficient properties as a hot and bulky spunbond cloth. Regarding the uniformity of thickness, it is stated that the thickness is slightly different between the center and the periphery, and includes a mat structure in which the thickness changes continuously. This difference in thickness is 20mm like a matuto structure.
However, in the case of a low basis weight spunbond nonwoven fabric such as a top sheet of the present invention, such thickness uniformity is not acceptable as a product.

Furthermore, each filament of the bulky mat-like fiber structure of JP-A-48-1471 is arranged in a substantially random direction, and the arrangement of the filaments hardly changes in the vertical and horizontal directions of the mat. It is stated that when a square sample piece cut to 5 to 20 mm in both the vertical and horizontal directions is set in a normal tensile testing machine and pulled under a constant load, the elongation rate does not differ by more than 30% in the vertical and horizontal directions.

Regarding this point, in fields with low basis weight such as top sheets, which are the target of the spunbond nonwoven fabric of the present invention, there is no difference in vertical and horizontal elongation rates.
Due to problems during the manufacturing process, it is necessary to have a rather low elongation rate in the vertical direction, and a material that has a high horizontal elongation but a small vertical elongation is required.

Furthermore, in T57-62 of the Japanese Patent Publication No. 13741/1974 and the Journal of the Japan Society of Fiber Science and Technology (Collection of Papers) Vol. 29, No. 4 (1976), which explains in detail the technology disclosed in the publication, polypropylene produced by an asymmetric cooling method is described. A crimped fiber is disclosed. 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, it is extremely difficult to uniformly cause crimp development in a large number of filaments, such as spunbond nonwoven fabric, by stretching the undrawn yarn from a non-crimped state to develop crimp. It is difficult to obtain uniform bulky spunbond.

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

[Means to solve the problem]

The above-mentioned object of the present invention is to provide a spunbond nonwoven fabric made of a single component thermoplastic resin, partially thermocompressed and having a basis weight of 50 g/m ² or less and a thickness of 5 mm or less, wherein the filaments constituting the nonwoven fabric have a specific cross section as described below. A partial thermocompression bonded part that has a shape, is continuous in the longitudinal direction of the nonwoven fabric as a whole while drawing a gentle curve, and has a plurality of filaments adjacent to each other over almost the entire surface upward and downward of the nonwoven fabric. It rises in between to form a loop with a helical diameter of 1 mm or less, and the shortest distance between each partial thermocompression bonding part is 1.0 mm.
mm or more, and is achieved by a bulky spunbond nonwoven fabric characterized in that the partial thermocompression bonded portion is located approximately at the center within the cross section of the nonwoven fabric.

As the thermoplastic resin, polypropylene,
Polyethylene, polyester, etc. can be used. A crystalline thermoplastic resin is preferably used, but polypropylene is more preferably used especially in order to obtain a bulky and flexible spunbond nonwoven fabric. That is, a crystalline thermoplastic resin tends to cause crystallization deviation in the cross-sectional direction of the filament during the process of cooling and solidifying to develop crimp, and is preferable for developing bulkiness. In particular, in the case of polypropylene, since the resin itself is flexible, a more flexible and bulky spunbond nonwoven fabric can be obtained.

The specific cross section may be a polygonal cross section such as a triangular cross section, or an irregular cross section having various cross-sectional shapes such as a C-shaped cross section. However, in order to obtain bulkiness and flexibility, it is preferable to use an irregular cross-section yarn with a cross-sectional shape with protruding parts than a solid irregular cross-section yarn, and it is necessary that the shape satisfies the following formula. be.

L≧1.3l...(1) L: Perimeter of irregular cross section l: Perimeter of round cross section of the same denier as the filament with irregular cross section above If L<1.3l, point upward and downward of the nonwoven fabric. The formation of loops due to the rise of the plurality of filaments over almost the entire surface of the fabric is insufficient, and a bulky spunbond nonwoven fabric cannot be obtained. L
By setting ≧1.3l, in addition to sufficient loop formation due to upward and downward swelling of the constituent filaments to form a bulky spunbond nonwoven fabric, it is possible to form circles with the same denier. There is also the effect that the apparent diameter of the filament is larger than that of the shaped cross-section yarn or the irregular cross-section yarn with L<1.3l, resulting in a good bulky spunbond nonwoven fabric. However, if the cross-sectional shape of the filament is flat as a whole, the flat surfaces tend to overlap and the repulsive force against external forces is small. A bulging shape is preferred (see Figure 5b).One of the features of the present invention is that it is a spunbond nonwoven fabric consisting of a single component polymer.

Unlike the case of two-component spunbond fabrics, the production of nonwoven fabrics does not require complicated equipment, which is advantageous in terms of cost, and the resulting nonwoven fabrics are also advantageous in terms of industrial reuse. be.

In terms of products, especially in the case of polypropylene, the inherent softness of the material is added to the product, resulting in an extremely bulky and flexible spunbond nonwoven fabric.

The filaments constituting the spunbond nonwoven fabric of the present invention were sampled before partial thermocompression bonding, and when exposed to no external restraining force, they had helical crimp, and under a load of 2 mg/d. When the number of crimp per inch is measured, the number of crimp is 8 to 15 per inch.

In order to suppress vertical elongation during the manufacturing and processing processes, the filaments that make up the spunbond nonwoven fabric form a gentle curve while maintaining the overall structure by applying appropriate tensile action and applying partial heat bonding during web transport. appear to be continuous in the longitudinal direction of the nonwoven fabric.

It is very important to partially heat bond the crimped filament with a moderate amount of tension, so that when it is collected on the wire mesh conveyor, the crimped filament will form a helical shape in all directions. Due to moderate tension, the filament, which had been in the form of a filament, becomes a laminated web that is stretched into a gently looped shape, remains in a spiral shape, or is in an intermediate state, and is partially thermally bonded in this state. As a result, a spunbond nonwoven fabric as shown in the micrograph of FIG. 1A is obtained.

Among these, the portion having a spiral shape contributes to the bulk and flexibility of the spunbond nonwoven fabric,
On the other hand, the filament, which has been stretched to form a gentle curve, suppresses elongation in the vertical direction during manufacturing and processing processes.

Furthermore, since the filament, which has crimps and attempts to take on a spiral shape, is stretched and partially thermocompressed, the nonwoven fabric is constructed in a slightly distorted form, and the compression on the surface of the spunbond nonwoven fabric, etc. It has a moderate repulsion force against external force.

The appropriate tensile action is preferably about 10%.

The length of the constituent filaments taken before partial thermocompression bonding is 1.4 to 2.0 times longer at 100 mg/d than the length at 2 mg/d.

A plurality of filaments extend upward and downward over almost the entire surface of the nonwoven fabric between adjacent thermocompression bonded parts to form loops.

This loop can be clearly observed in the cross-sectional photograph of the spunbond nonwoven fabric in the horizontal direction (Fig. 1B).
It is preferable that the helical diameter of the loop is 1.0 mm or less. If the helical diameter exceeds 1.0 mm, the number of crimps per unit length will be small, resulting in poor bulkiness and flexibility, as well as a rough texture on the skin, which is undesirable.

In the micrograph, the filaments constituting the nonwoven fabric were cut because the nonwoven fabric was cut out to take a cross-sectional photo, and it can be seen that the filaments released from the partial thermocompression bond form a spiral loop. This photo shows that the filament, which attempts to take on a spiral shape, forms a nonwoven fabric in a distorted manner.

For partial thermocompression bonding, if the spacing between the thermocompression bonding parts is small, the spiral loop of the crimped filament will be too constrained to the nonwoven fabric surface and the bulk will be lost, so a spacing of 0.5 mm or more is required. It is. Furthermore,
The shortest distance between each partial thermocompression bonding part is 1.0 mm or more,
The one in which the partial thermocompression bonded part is located approximately in the center of the cross-section of the nonwoven fabric is an extremely good bulky spunbond because the hard feel of the partial thermocompression bonded part does not appear on the surface of the nonwoven fabric. The bulky spunbond nonwoven fabric according to the present invention can be preferably used in fields such as top sheets of disposable diapers. When used in such fields, if the basis weight of the nonwoven fabric is less than 10 g/m ² , the nonwoven fabric will lack strength, and if it exceeds 50 g/m ² , it is unfavorable from an economic standpoint.

As a method of partial thermocompression bonding, a method of heating a roll engraved with a desired design and a mirror-finished roll and thermocompression bonding between them, or a method of thermal bonding using ultrasonic waves can be used. The method of bonding using ultrasonic waves is advantageous because it allows rolls with deep engravings suitable for partial thermal bonding of bulky spunbonds to be produced at low cost without being equipped with heating equipment.

The spunbond nonwoven fabric according to the present invention has bulkiness as described above. In the present invention, the bulkiness is 10g/
The value obtained by dividing the thickness (μ) at a load of 4 cm ² by the basis weight (g/m ² ) is expressed as the bulk factor H, and the value of H is preferably 20 or more.

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

FIG. 1 shows electron micrographs (40x magnification) of the present invention in the planar direction (FIG. 1A) and the thickness direction (FIG. 1B). From these photographs, it can be seen that the filaments constituting the present invention have irregular cross-sections and are continuous in the longitudinal direction of the non-woven fabric while drawing a gentle curve, and that the filaments that constitute the present invention are continuous in the longitudinal direction of the non-woven fabric as a whole. It can be observed that the filaments form a loop between adjacent partial thermocompression bonded parts.

FIG. 2 shows electron micrographs (40x magnification) of a conventionally known long fiber nonwoven fabric in the plane direction (FIG. 2A) and the thickness direction (FIG. 2B). As shown in these photographs, in conventionally known long fiber nonwoven fabrics, the filaments constituting the nonwoven fabric have a round cross section and are arranged in a straight line with a lack of bulk.

From FIG. 1B and FIG. 2B, it can be easily determined that the bulk of the nonwoven fabric of the present invention is higher than conventionally known long fiber nonwoven fabrics.

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

FIG. 5 illustrates the cross-sectional shape of a filament constituting the nonwoven fabric of the present invention. Any filament with an irregular cross section has a cross-sectional shape having a convex portion.

Next, the method for manufacturing the bulky spunbond nonwoven fabric of the present invention will be explained with reference to FIG.

The spunbond nonwoven fabric of the present invention is produced by melt-extruding a thermoplastic resin such as polypropylene through a unique die 1, cooling the filament using a cold air device 2, and taking it off with a high-speed traction device 3 such as a high-speed air suction car. The cooling described here is 20℃, 70%
It is sufficient to use cooling air at around RH.

The yarn leaving the high-speed traction device 3 passes through a charging device 4, is collected as a web 10 on a moving wire mesh conveyor 5, is conveyed, and is thermocompressed by partial thermocompression rolls 6 and 7. The spunbond nonwoven fabric 11 is wound up using a winding machine 8 .

When producing 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 appears as an apparent crimp when it is collected as a web on the collection surface.

Although the windward side cools and solidifies, it is elongated by the traction force of the high-speed traction device, and in this state, the leeward side cools and solidifies, so when the traction force is released, only the windward side that had been elongated shrinks, resulting in apparent winding. It is thought that this causes shrinkage. When polypropylene is used as the raw material, the crimped filament of the present invention has a density of 0.900 or less, but conventional filaments without crimps have a density of more than 0.905, and the density of the part that is cooled and solidified first on the windward side is It is thought that crystallization of about 0.895 is extremely suppressed.

In addition, a speed difference of about 10% is provided between the wire mesh conveyor and the partial heat bonding roll in order to give an appropriate tensile effect to the web collected on the wire mesh conveyor.

In conventional filament webs without crimping,
If a large tensile force of about 10% is applied, the web will slip off at a certain point, but the crimped web of the present invention can withstand such a large tensile force.
It is thought that a crimped spunbond nonwoven fabric that does not cause shearing of the web and draws gentle curves in the longitudinal direction is provided as long as the crimps are stretched.

Furthermore, the shortest distance between the bonding points of the partial heat-bonding roll is set to 1.0 mm or more, so that the mirror-finish roll is held when being transferred from the wire mesh conveyor to the partial heat-bonding roll (in Fig. 6, 7 indicates that the mirror-finish roll 6 is By performing partial thermocompression bonding with the nonwoven fabric (formed into an engraved roll), the partial thermocompression portion can be positioned approximately at the center in the cross-sectional direction of the nonwoven fabric.

In FIG. 1B, it can be observed that a large number of filaments are partially thermocompressed and are located approximately in the center in the cross-sectional direction of the nonwoven fabric.

〔Example〕

The present invention will be explained in more 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 1 m ² of nonwoven fabric.

◎High bulk factor (H) Compressive elasticity tester E-2 manufactured by Nakayama Electric Industry Co., Ltd.
Using a mold, the thickness T (μ) of the nonwoven fabric at a load of 10 g is measured under a measurement area of 4 cm ² and is expressed as the value divided by the basis weight.

H=T/Weight ◎ Helix diameter: The diameter of the loops in the nonwoven fabric is measured under a microscope photograph, and the average value (mm) is used.

◎MFR: JIS K7210 Measured under condition 4 in Table 1 and indicates the ease of polymer flow.

◎ Cut a 5% modulus nonwoven fabric in the vertical direction into a rectangular shape with a width of 3 cm so that the tensile direction is the vertical direction.
A tensile test was performed at cm/min, and the stress at 5% elongation was expressed in Kg.

◎Flexibility JIS L1096 bending and bending using E method (6, 19, 5
Measured using the handle-o-meter method).

◎Peripheral length of filament cross section: L A microscopic photograph of the filament cross section was taken, the circumferential length was measured, and the average value of 10 filaments was determined.

◎Perimeter of round-section filament of the same denier: l
It was calculated as a completely circular cross section.

Example 1 Polypropylene (MFR=
38JIS K7210 table, condition 4) at an extrusion temperature of 240
Extruded quantitatively at 1300g/min at ℃, 1m in the longitudinal direction with a 1540-hole Y-shaped irregular nozzle (220 rows in the longitudinal direction and 7 rows equally spaced in the width direction).
By using a rectangular spinneret with a width of 5 cm, a group of irregularly shaped filaments was spun, which was pulled at a speed of 3500 m/min by using a rectangular high-speed airflow traction device, and then charged by a corona charging device. ,
A receiving web was created on a wire mesh web conveyor equipped with a moving suction device.

A cooling device is installed between the spinneret and the rectangular high-speed airflow traction device to cool the filament group, and cooling air (70% R.
H.20℃) was applied.

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 having a basis weight of 20 g/m ² as shown in FIG. At this time, the speeds of the conveyor, partial thermocompression roll, and winding machine were 44 m/min and 49.0 m/min, respectively.
50m/min. The embossing roll used for partial thermocompression has a crimping area of 7%, the shortest distance between crimping points is 1.5 mm, and the depth of the embossing engraving is 0.8 mm.
It was hot.

The bulk factor of the obtained nonwoven fabric is 28,
The flexibility was 11.8g in the vertical direction and 5.0g in the horizontal direction.
The 5% modulus in the longitudinal direction was 0.50 kg/3 cm width, and the nonwoven fabric had good bulk and flexibility. The denier of the constituting filament was 2.2 denier (l=58μ), and L obtained from a cross-sectional photograph of the filament was 81μ.

Example 2 Under the same conditions as Example 2 except that the speeds of the conveyor, thermocompression roll, and winding machine were 58 m/min, 64 m/min, and 65 m/min, respectively, 15 g/m ²
A spunbond nonwoven fabric with a certain weight was obtained. The obtained nonwoven fabric has a bulk factor of 29 and a flexibility of 7.7 in the vertical direction.
g, and 4.8 g in the horizontal direction. The 5% modulus in the vertical direction was 0.45Kg/3cm width.

Example 3 Same conditions as Example 2 except that the amount of melt extrusion was 1540 g/min, and the speeds of the conveyor, partial thermocompression roll, and crimper were 51 m/min, 57 m/min, and 58 m/min, respectively. A nonwoven fabric with a fabric weight of 20 g/m ² was obtained. The bulk factor H of the obtained nonwoven fabric is
28, and the flexibility is 12.4g in the vertical direction and 12.4g in the horizontal direction.
It was 5.3g. The cross-sectional shape of the filament was trilobal, L was 85μ, and denier was 2.6 denier (l=63μ).

Comparative Example 1 A spunbond nonwoven fabric was obtained under the same conditions as in Example 1, except that a spinneret with a round spinning nozzle and a rectangular cross section was used, and the speed of the wire mesh conveyor was changed to 47 m/min.

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

Comparative Example 2 In Example 1, a Y-shaped irregular nozzle was used and L=
The triangular cross section is 1.2l, and the conveyor speed is 47m/
A spunbond nonwoven fabric was obtained under the same conditions except that the amount of spunbond nonwoven fabric was increased.

The number of filament crimps was 3/25 mm, and the obtained nonwoven fabric had a bulk factor of 18 and lacked bulk.

The flexibility of the non-woven fabric is 16.8g in the vertical direction and 7.0g in the horizontal direction.
The 5% modulus in the vertical direction was 1.2Kg/3cm width.

Comparative Example 3 The same conditions as Example 1 were used, except that the embossing roll for partial thermocompression used in Example 1 had a crimping area of 30% and the shortest distance between the partial thermocompression parts was 0.4 mm. / ^m2 spunbond nonwoven fabric was obtained.

An average of 10/25 filaments before partial thermocompression bonding
Although a crimp number of mm was observed, the obtained spunbond nonwoven fabric had a bulk factor of 19 and lacked bulk.

〔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 fibers and low cost, it can be usefully used in a wide range of applications such as diaper top sheets.

[Brief explanation of drawings]

FIG. 1 is a photomicrograph showing the shape of the constituent fibers of the nonwoven fabric of the present invention, FIG. 1A is a photo in the planar direction, and FIG. 1B is a photo 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. It is. FIG. 5 is a diagram illustrating the cross-sectional shapes of various filaments constituting the nonwoven fabric of the present invention.
FIG. 6 is a side view showing an example of the nonwoven fabric manufacturing apparatus of the present invention. 1... Mouthpiece, 2... Cooling device, 3... High speed traction device, 4... Charging device, 5... Wire mesh conveyor, 6, 7... Partial thermocompression bonding roll, 8... Winding machine.

Claims (1)

[Scope of Claims] 1. A spunbond nonwoven fabric made of a single component thermoplastic resin and partially thermocompressed and having a basis weight of 50 g/m ² or less and a thickness of 5 mm or less, wherein the filament constituting the nonwoven fabric has the following formula (1 ), the nonwoven fabric as a whole is continuous in the longitudinal direction while drawing a gentle curve, and multiple filaments are adjacent to each other over almost the entire surface upward and downward of the nonwoven fabric. It rises between the partial heat-compressed parts to form a loop with a helical diameter of 1 mm or less,
The shortest distance between each partial thermocompression bonding part is 1.0 mm or more,
The bulky spunbond nonwoven fabric is characterized in that the partial thermocompression bonded portion is located approximately at the center within the cross section of the nonwoven fabric. L>1.3l...(1) L: Circumferential length of irregular cross section l: Circumferential length of round cross section filament having the same denier as the aforementioned irregular cross section filament 2 A claim characterized in that the thermoplastic resin is polypropylene. 1. The bulky spunbond nonwoven fabric according to item 1. 3. The bulky spunbond nonwoven fabric according to claim 1, wherein the thermoplastic resin is polypropylene.