WO2021256146A1

WO2021256146A1 - Spun-bonded nonwoven fabric and sanitary material

Info

Publication number: WO2021256146A1
Application number: PCT/JP2021/018742
Authority: WO
Inventors: 梶原健太郎; 森岡英樹; 船津義嗣
Original assignee: 東レ株式会社
Priority date: 2020-06-15
Filing date: 2021-05-18
Publication date: 2021-12-23
Also published as: TW202210677A; JPWO2021256146A1; KR20230024256A

Abstract

The present invention provides a spun-bonded nonwoven fabric which has water absorption and quick-drying properties that are sufficient to maintain comfort when worn, and which has a texture that feels soft. This spun-bonded nonwoven fabric is suitable for use in a sanitary material.　A spun-bonded nonwoven fabric which has a fused part and a non-fused part, wherein: the ratio of the average single fiber diameter (Da) of the fibers in one surface (A) to the average single fiber diameter (Db) of the fibers in the other surface (B), namely Da/Db is 1.1 or more; the contact angles with water of the surface (A) and the surface (B) are both 30° or less; and the tortuosity of the fibers in the surface (A) is 1.1 or more.

Description

Spun-bonded non-woven fabric and sanitary materials

The present invention relates to a spunbonded nonwoven fabric that has both excellent water absorption and quick-drying properties and a soft touch, and is particularly suitable for sanitary material applications, and sanitary materials using the same.

In recent years, various studies have been conducted to further improve the wearing comfort of non-woven fabrics used for sanitary materials such as disposable diapers, sanitary napkins, and masks. In particular, for surface members that come into direct contact with the skin, both water absorption that quickly absorbs moisture and quick-drying that transfers the absorbed moisture from the outermost surface layer to make the surface smooth without excessive dampness, that is, "water absorption". "Quick drying" is required. At the same time, a soft touch to the skin is also required.

Although it is effective to use a non-woven fabric made of hydrophilic fibers or to apply a hydrophilic treatment to the non-woven fabric as a means for imparting water absorption to the non-woven fabric, these techniques allow water absorbed from the outermost layer. The quick-drying property was not sufficient because there was no migration function.

Against this background, a spunbonded nonwoven fabric having a laminated structure of fiber layers containing long fibers for the purpose of imparting water absorption and quick-drying to the nonwoven fabric, the distance between the hydrophobic layer containing the hydrophobic fibers and the flatness and flatness. A spunbonded nonwoven fabric composed of a hydrophilic layer containing hydrophilic fibers having a ratio in a specific range and having the hydrophobic layer arranged on the surface of the nonwoven fabric has been proposed (see Patent Document 1).

Separately, as a technique for laminating a non-woven fabric, a higher average non-woven fabric diameter is provided between the first and third non-woven fabric constituent layers containing fibers having an average non-woven fabric diameter in a specific range and the first and third non-woven fabric layers. An absorbent article containing a spunbonded nonwoven fabric for arranging a second nonwoven fabric constituent layer containing the fine fibers of the above has been proposed (see Patent Document 2).

International Publication No. 2018/167881 Special Table 2013-51898 Gazette

In the technique of Patent Document 1, a hydrophilic gradient is formed in the thickness direction of the nonwoven fabric, so that a certain water absorption performance is exhibited even on a surface in which a hydrophobic layer is arranged on the outermost surface layer. However, since the outermost surface is a hydrophobic layer, the performance is not sufficient for absorbing a large amount of water such as urine, and the quick-drying property is also insufficient because liquid residue is likely to occur. In addition, the softness of the surface that touches the skin was not sufficient.

On the other hand, the technique of Patent Document 2 relates to a spunbonded nonwoven fabric having a structure in which a nonwoven fabric layer composed of fibers having different average single fiber diameters is laminated. However, since this non-woven fabric is used for a barrier cuff, it has a structure that prevents fluid from strike through, that is, has a structure that does not allow moisture to pass through, and liquid residue is likely to occur on the surface of the non-woven fabric, so that water absorption and quick-drying are insufficient. Met. In addition, the softness of the surface that touches the skin was not sufficient.

Therefore, an object of the present invention has been made in view of the above circumstances, and is a spunbond having sufficient water absorption and quick-drying property to maintain comfort when worn, and having a soft touch. It is an object of the present invention to provide a spunbonded nonwoven fabric which is a nonwoven fabric and is preferably used as a sanitary material.

As a result of the study by the present inventors, it is effective to increase the hydrophilicity of the non-woven fabric itself in order to increase the water absorption of the non-woven fabric. It was confirmed that the product did not dry as it was contained, causing problems such as inferior comfort when worn. On the other hand, when hydrophobic fibers are used for a part of the nonwoven fabric for the purpose of improving quick-drying, or when a hydrophilicity gradient is given in the thickness direction, the water absorption of the nonwoven fabric surface is lowered as a result, and the liquid remains. It was also found that problems such as these occur.

Therefore, as a result of further diligent studies in order to achieve the above-mentioned problems, the present inventors have a fused portion and a non-fused portion in the spunbonded nonwoven fabric, and the fibers constituting one surface (A). And the ratio of the average single fiber diameters of the fibers constituting the other surface (B), and the contact angle between the surface (A) and the water of the surface (B) within a specific range, and the surface (A). It has been found that by setting the degree of bending of the constituent fibers within a specific range, the non-woven fabric has sufficient water absorption and quick-drying property to maintain comfort when worn, and has a soft touch feeling.

The present invention has been completed based on these findings, and the following inventions are provided according to the present invention.

The spunbonded nonwoven fabric of the present invention has a fused portion and a non-fused portion, and has an average single fiber diameter (Da) of fibers on one surface (A) and an average single fiber of fibers on the other surface (B). The ratio (Da / Db) to the diameter (Db) is 1.1 or more, the contact angles of the surface (A) and the surface (B) with water are both 30 ° or less, and the surface ( The degree of bending of the fiber of A) is 1.1 or more.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the diameter of the maximum inscribed circle of the non-fused portion is 2.0 mm or more.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the thickness (Tu) of the spunbonded nonwoven fabric in the non-fused portion is 0.5 mm or more.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the ratio (Tu / Tm) of the thickness (Tu) of the spunbonded nonwoven fabric in the non-fused portion to the thickness (Tm) of the spunbonded nonwoven fabric in the fused portion. ) Is 2.0 or more.

According to a preferred embodiment of the spunbonded nonwoven fabric of the present invention, the tortuosity of the fibers on the surface (B) is 1.1 or less.

Further, the sanitary material of the present invention is at least partially composed of the above-mentioned spunbonded nonwoven fabric.

According to a preferred embodiment of the sanitary material of the present invention, the surface (A) is arranged toward the skin side of the wearer.

According to the present invention, it is possible to obtain a spunbonded nonwoven fabric which is excellent in water absorption and quick-drying property and soft touch, and which is particularly suitable for sanitary material applications, and sanitary materials using the same.

FIG. 1 is a top conceptual diagram illustrating a method for determining the maximum inscribed circle of a non-fused portion in one embodiment of the spunbonded nonwoven fabric of the present invention. FIG. 2 is a top conceptual diagram illustrating a method for determining the maximum inscribed circle of the non-fused portion in another embodiment of the spunbonded nonwoven fabric of the present invention. FIG. 3 is a top conceptual diagram illustrating a method for determining the maximum inscribed circle of the non-fused portion in still another embodiment of the spunbonded nonwoven fabric of the present invention.

The spunbonded nonwoven fabric of the present invention has a fused portion and a non-fused portion, and has an average single fiber diameter (Da) of fibers on one surface (A) and an average single fiber of fibers on the other surface (B). The ratio (Da / Db) to the diameter (Db) is 1.1 or more, the contact angles of the surface (A) and the surface (B) with water are both 30 ° or less, and the surface ( The degree of bending of the fiber of A) is 1.1 or more. The components thereof will be described in detail below, but the present invention is not limited to the scope described below as long as the gist thereof is not exceeded.

[fiber]
The spunbonded nonwoven fabric of the present invention is preferably made of a thermoplastic resin. The thermoplastic resin may be one kind or may be composed of a plurality of thermoplastic resins.

Examples of the thermoplastic resin used for the fiber according to the present invention include aromatic polyester polymers such as "polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate" and copolymers thereof, "polylactic acid". , Polyethylene succinate, Polybutylene succinate, Polybutylene succinate adipate, Polyhydroxybutyrate-Polyhydroxyvariate copolymer, Polycaprolactone "and other aliphatic polyester polymers and copolymers thereof," Polyethylene 6, Polyamide An aliphatic polyamide polymer such as "66, polyamide 610, polyamide 10, polyamide 12, polyamide 6-12" and its copolymer, and a polyolefin polymer such as "polypropylene, polyethylene, polybutene, polymethylpentene" and its copolymer. ,
A water-insoluble ethylene-vinyl alcohol copolymer polymer containing 25 mol% to 70 mol% of ethylene units,
Polystyrene-based, polydiene-based, chlorine-based, polyolefin-based, polyester-based, polyurethane-based, polyamide-based, fluorine-based elastomer-based polymers and the like can be selected and used. In the above polymers, various additives such as titanium oxide, silica, inorganic substances such as barium oxide, carbon black, colorants such as dyes and pigments, flame retardants, fluorescent whitening agents, antioxidants, and ultraviolet absorbers are added. The agent may be contained in the polymer.

The fiber in the present invention may be not only a single component fiber but also a composite fiber in which two or more kinds of resins are composited. When the above fiber is a composite fiber, it is not particularly limited as long as it does not impair the effect of the present invention, and may be appropriately selected from a core sheath type, a sea island type, a side-by-side type, an eccentric core sheath type and the like. Further, it may be a split fiber type composite fiber in which a part or the whole of the fiber is divided into a plurality of fibers from one fiber.

The cross-sectional shape of the fiber in the present invention is not particularly limited as long as the effect of the present invention is not impaired, and may be a triangular, flat, hexagonal, hollow, or other irregular cross-section as well as a round cross-section.

It is preferable that all the fibers in the present invention have a contact angle with water of 90 ° or less. The contact angle of the fiber with water is an index different from the contact angle with water on the surface of the nonwoven fabric described later, and if the contact angle exceeds 90 °, it becomes hydrophobic, and if it is 90 ° or less, it becomes hydrophilic. Since the fibers have a contact angle with water of 90 ° or less, the contact angle of the surface of the nonwoven fabric with water can be easily set to 30 ° or less.

The contact angle of the fiber with water in the present invention is, for example, an automatic contact equipped with an inkjet water droplet ejection unit with respect to the fiber taken out from the non-woven fabric left in a room at room temperature of 20 ° C. and relative humidity of 65% for 24 hours or more. It is obtained by measuring the angle between the air interface of the droplet and the fiber when a very small amount (15 pL) of water droplet is landed on the fiber surface using a horn meter.

It should be noted that the type of the thermoplastic resin constituting the fiber on the surface (A) and the fiber on the surface (B) may have the same or different fiber cross sections.

[Surface (A)]
The surface (A) of the spunbonded nonwoven fabric of the present invention is composed of the fibers made of the above-mentioned thermoplastic resin.

The spunbonded nonwoven fabric of the present invention is preferably made of long fibers, and the constituent fibers of the surface (A) are preferably long fibers. This is because it is easy to achieve both high productivity and excellent mechanical characteristics because it is made of long fibers.

The average single fiber diameter of the fibers constituting the surface (A) of the spunbonded nonwoven fabric of the present invention is preferably 3.0 to 30.0 μm. The average single fiber diameter of the fibers constituting the surface (A) is preferably 3.0 μm or more, more preferably 5.0 μm or more, and further preferably 10.0 μm or more. By setting the average single fiber diameter of the fibers constituting the surface (A) to 3.0 μm or more, when used as a sanitary material, moisture is easily transferred to the adjacent water absorber. The average single fiber diameter of the fibers constituting the surface (A) is preferably 30.0 μm or less, more preferably 28.0 μm or less, and further preferably 25.0 μm or less. By setting the average single fiber diameter of the fibers constituting the surface (A) to 30.0 μm or less, it is easy to obtain a soft texture.

The average single fiber diameter referred to here is calculated as follows.

First, an image is taken of the cross section of the fibers constituting one surface at a magnification at which one fiber can be observed with a scanning electron microscope. Subsequently, using the captured image, using image analysis software (for example, "WinROOF2015" manufactured by Mitani Corporation), the area Af (μm ² ) formed by the cross-sectional contour of the single fiber is measured, and this area Af is used. Calculate the diameter of a perfect circle with the same area. This is arbitrarily extracted and measured for 20 fibers constituting the same surface, a simple number average is obtained, the unit is μm, and the value rounded to the second decimal place is the average single fiber on the surface referred to in the present invention. Let it be the diameter.

The spunbonded nonwoven fabric of the present invention has a bending degree of fibers on the surface (A) of 1.1 or more. The bending degree of the fiber on the surface (A) is preferably 1.2 or more, more preferably 1.3 or more. This is because a high water absorption rate can be obtained when the bending degree of the fiber on the surface (A) is 1.1 or more. The mechanism by which a high water absorption rate is obtained is not clear, but it is presumed to be the effect of forming various interfiber voids. Further, when the bending degree of the fiber on the surface (A) is 1.1 or more, it becomes easy to obtain a soft touch feeling. The upper limit of the bending degree of the fiber on the surface (A) is not particularly limited, but is preferably 10.0 or less from the viewpoint of process stability and productivity.

The degree of fiber bending referred to here is obtained as follows.

First, an image is taken of one surface with a scanning electron microscope at a magnification that allows one fiber to be observed in a straight line over 500 μm. Then, using the captured image, using image analysis software (for example, National Institutes of Health "ImageJ"), the apparent length of the fiber was measured between two linear fibrous points of 500 μm. , The apparent length of this fiber is divided by 500 μm to calculate the apparent length / linear length. This is arbitrarily extracted and measured for 20 fibers constituting the same surface, a simple number average is obtained, and the value rounded to the second decimal place is defined as the tortuosity of the fibers on the surface in the present invention.

[Surface (B)]
The surface (B) of the spunbonded nonwoven fabric of the present invention is composed of fibers made of the above-mentioned thermoplastic resin, similarly to the surface (A).

The spunbonded nonwoven fabric of the present invention is preferably made of long fibers, and the constituent fibers of the surface (B) are preferably long fibers as in the surface (A). This is because it is easy to achieve both high productivity and excellent mechanical characteristics because it is made of long fibers.

The average single fiber diameter of the fibers constituting the surface (B) of the spunbonded nonwoven fabric of the present invention is preferably 1.0 to 25.0 μm. The average single fiber diameter of the fibers constituting the surface (B) is preferably 1.0 μm or more, more preferably 3.0 μm or more, still more preferably 5.0 μm or more. This is because when the size is 1.0 μm or more, the arrangement of the fibers does not become too dense, and when used as a material for disposable diapers, water easily transfers to the adjacent water absorber. The average single fiber diameter of the fibers constituting the surface (B) is preferably 25.0 μm or less, more preferably 20.0 μm or less, still more preferably 16.0 μm or less. This is because when the thickness is 25.0 μm or less, high capillary force can be easily obtained and excellent water absorption can be obtained.

The degree of bending of the fibers on the surface (B) of the spunbonded nonwoven fabric of the present invention is preferably 1.1 or less, more preferably 1.0. This is because when the bending degree of the fibers on the surface (B) is 1.1 or less, it is easy to form small interfiber voids and it is easy to obtain a high capillary force. The lower limit of the bending degree of the fiber on the surface (B) is 1.0, which is included when the apparent length and the length in a straight line match, which is a preferable embodiment.

[Average single fiber diameter of surface (A) and surface (B)]
In the spunbonded nonwoven fabric of the present invention, the ratio (Da / Db) of the average single fiber diameter (Da) of one surface (A) to the average single fiber diameter (Db) of the fibers of the other surface (B), hereinafter simply " (Sometimes abbreviated as "average single fiber diameter ratio") is 1.1 or more.

The average single fiber diameter ratio referred to here is the average single fiber diameter (Da) of the fibers constituting the surface (A) and the average single fiber diameter (B) of the fibers constituting the surface (B) by using the above-mentioned method. Db) is measured, the ratio (Da / Db) is calculated, and the value is rounded off to the second digit.

Generally, in a non-woven fabric, the size of the voids woven by the fibers changes according to the average single fiber diameter of the constituent fibers. Therefore, when layers with different average single fiber diameters are formed, layers with different interfiber void sizes are formed, and when moisture adheres, the layer is made of thick fibers due to the difference in capillary force. The absorbed moisture can be transferred to a layer of fine fibers. Furthermore, as a result of diligent studies, the present inventors have set this average single fiber diameter ratio within a specific range, which not only has an effect of improving water absorption due to the difference in capillary effect, but also has a rapid effect on the surface of a non-woven fabric layer made of thick fibers. It has been found that dryness is imparted.

The average single fiber diameter ratio (Da / Db) in the present invention is preferably 1.2 or more, more preferably 1.3 or more, and even more preferably 1.4 or more. By setting the average single fiber diameter ratio (Da / Db) to 1.1 or more, the above-mentioned capillary effect acts, and good water absorption and quick-drying on the surface (A) can be obtained. The upper limit of the average single fiber diameter ratio in the present invention is not particularly limited, but is preferably 10.0 or less from the viewpoint of process stability and productivity.

[Spanbond non-woven fabric]
As described above, the spunbonded nonwoven fabric of the present invention has a fused portion and a non-fused portion. The fused portion is a portion where the fiber on the surface (A) and the fiber on the surface (B) are fused, and the non-fused portion is a portion other than that on the spunbonded nonwoven fabric. , The area surrounded by the fused part. In the fused portion, since the fiber on the surface (A) and the fiber on the surface (B) are fused, the density around the fused portion tends to be high. The presence of a high-density fused portion and a relatively low-density non-fused portion in the plane of the spunbonded non-woven fabric facilitates the movement of water in the plane and is simple in the thickness direction. It is possible to facilitate the development of more efficient water absorption and quick-drying performance than the movement of water.

In the present invention, whether or not the portion is a fused portion in a part of the spunbonded nonwoven fabric, that is, a portion where the fiber on the surface (A) and the fiber on the surface (B) are fused. Whether or not the surface (A) is arbitrarily selected by observing an image of the cross section of the relevant portion of the spunbonded nonwoven fabric as a magnification in which the thickness direction of the spunbonded nonwoven fabric is in the field of view with a scanning electron microscope. If the surface (B) of the fused portion is fused at the same position in the plane direction, it is determined that the portion is the fused portion.

Further, in the spunbonded nonwoven fabric of the present invention, it is preferable that the diameter of the maximum inscribed circle of the non-fused portion is 2.0 mm or more. The diameter of the maximum inscribed circle is more preferably 3.0 mm or more, further preferably 4.0 mm or more. This is because when the diameter of the maximum inscribed circle is 2.0 mm or more, it is easy to form a low-density portion sufficiently distant from the fused portion, so that a high water absorption rate can be easily obtained. It is also preferable in that it is easy to obtain a soft touch. The diameter of the maximum inscribed circle is preferably 10.0 mm or less, more preferably 9.0 mm or less, still more preferably 8.0 mm or less. This is because when the diameter of the maximum inscribed circle is 10.0 mm or less, it is easy to suppress fluffing due to friction or the like.

As illustrated in FIGS. 1 to 3, the diameter of the maximum inscribed circle in the present invention is formed on the fused portion (11) with a microscope when the surface of the spunbonded nonwoven fabric (1) is observed from above. A field of view having a size of 10 mm × 10 mm or more in which the enclosed non-woven fabric can be observed is photographed. Then, using the captured image, the diameter of the maximum inscribed circle (13) that can be placed on the non-fused portion (12) is measured using image analysis software (for example, "WinROOF2015" manufactured by Mitani Corporation). do. This is arbitrarily extracted and measured at 20 points constituting the same surface, a simple number average is obtained, the unit is mm, and the value rounded to the second decimal place is the maximum inscribed circle of the surface in the present invention. Let it be the diameter.

The spunbonded nonwoven fabric of the present invention has one surface (A) in which the average single fiber diameter of the fiber is Da and the other surface (B) in which the average single fiber diameter of the fiber is Db, as described above. The average single fiber diameter ratio (Da / Db) is 1.1 or more. By doing so, the surface (A) in which the average single fiber diameter is large and the interfiber voids in the nonwoven fabric layer are likely to be large becomes the outermost layer, and when water is absorbed on the surface (A) side, the surface (A) is promptly absorbed. Since the water is transferred to the surface (B) side, quick-drying can be obtained on the outermost surface on the surface (A) side.

Further, in the spunbonded nonwoven fabric of the present invention, the contact angles of the surfaces (A) and the surface (B) of the spunbonded nonwoven fabric with water are both 30 ° or less. When the contact angles of the front and back surfaces of the spunbonded nonwoven fabric with water are both 30 ° or less, preferably 20 ° or less, more preferably 10 ° or less, the water in contact with the surface of the spunbonded nonwoven fabric is easily absorbed by the nonwoven fabric. .. Further, the lower limit of the contact angle with water in the present invention is 0 °, but the contact angle with water of 0 ° means a state in which all the water is absorbed by the non-woven fabric in the measurement method described later.

The contact angle of the surface of the spunbonded nonwoven fabric with water can be controlled by the hydrophilicity of the thermoplastic resin used for the fibers constituting the spunbonded nonwoven fabric and the addition of a hydrophilic oil agent in a subsequent process. For example, the higher the hydrophilicity of the thermoplastic resin and the larger the amount of the hydrophilic oil agent adhered to the resin, the smaller the contact angle with water tends to be.

The contact angle of the surface of the spunbonded nonwoven fabric of the present invention with water refers to a value measured and calculated by the following method.
(1) The spunbonded nonwoven fabric is left in a room at room temperature of 20 ° C. and relative humidity of 65% for 24 hours or more.
(2) The spunbonded nonwoven fabric subjected to the above treatment is set on the stage of the contact angle meter installed in the same room so that the surface (A) becomes the measurement surface.
(3) A 2 μL droplet composed of ion-exchanged water is prepared at the needle tip and landed on a non-woven fabric.
(4) The contact angle with the droplet is obtained from the image 2 seconds after the droplet has landed on the non-woven fabric. If all the water is absorbed by the non-woven fabric within 2 seconds, it is judged that the interface of the droplet with air is on the same surface as the surface of the non-woven fabric layer, and the contact angle with water is defined as 0 °. ..
(5) The measurement position is changed for each level, and the measurement is performed 5 times, and the arithmetic mean value is taken as the contact angle between the surface (A) and water.
(6) Set the spunbonded non-woven fabric subjected to the same treatment as (1) so that the front surface (A) is the back surface, repeat the above operations (2) to (5), and calculate the arithmetic mean value. The contact angle between the surface (B) and water.

The spunbonded non-woven fabric of the present invention has the highest breaking strength with respect to the _{lowest breaking strength σ min} measured by rotating in the plane of the spunbonded non-woven fabric up to 180 ° every 22.5 ° with 0 ° in any one direction. The ratio of breaking strength σ _max _{(σ max} / σ _min , hereinafter may be simply abbreviated as breaking strength ratio) is preferably 1.2 to 4.0. By setting the breaking strength ratio to preferably 1.2 or more, more preferably 1.3 or more, the fibers are easily oriented in the non-woven fabric surface, and high capillary force is easily developed. Therefore, the in-plane fibers are easily developed. It is possible to obtain higher water absorption and quick-drying property by causing the movement of the fiber. Further, by setting the breaking strength ratio to preferably 4.0 or less, more preferably 3.5 or less, an extremely low angle of breaking strength is eliminated, so that tearing of the non-woven fabric during process passage or product processing is suppressed. be able to.

The breaking strength ratio of the spunbonded nonwoven fabric of the present invention was measured and calculated by the following method based on "6.3 Tensile strength and elongation (ISO method)" of JIS L1913: 2010 "General nonwoven fabric test method". Point to a value.
(1) Set any one direction of the spunbonded nonwoven fabric to 0 °, cut out a test piece having a length of 300 mm and a width of 25 mm so that the vertical direction coincides with the above direction, change the location, and collect three test pieces.
(2) Grasp the test piece and set it in the tensile tester with an interval of 200 mm.
(3) A tensile test is carried out at a tensile speed of 100 m / min, the strength [N] at break is obtained for the three collected test pieces, and the arithmetic mean value thereof is defined as the breaking strength σ.
(4) The axis is the direction rotated clockwise by 22.5 ° in the plane of the spunbonded nonwoven fabric with respect to any one direction set to 0 °, and the vertical direction is 300 mm in length so as to coincide with the above axial direction. × Cut out a test piece with a width of 25 mm, change the location, and collect 3 test pieces. After that, the above operations (2) to (3) are performed to calculate the breaking strength σ.
(5) The operation of (4) above is repeated until the rotation angle of the spunbonded nonwoven fabric in the plane becomes 180 °, and the breaking strength σ at each angle is calculated.
(6) Of the breaking strength σ calculated by the above method, the ratio of the maximum breaking strength σ _max _{to the lowest breaking strength σ min} _{(σ max} / σ _min ) is calculated and used as the breaking strength ratio of the spunbonded non-woven fabric.

In the spunbonded nonwoven fabric of the present invention, the spunbonded nonwoven fabric layer (S) and the melt blow nonwoven fabric layer (M) can be arranged according to the purpose as long as the effects of the present invention are not impaired. Examples of these arrangements include aspects such as SMS, SMMS, SMSMS, SMSMS, and the like. In these cases, one surface of the laminated nonwoven fabric is regarded as the surface (A) of the spunbonded nonwoven fabric, and the other surface is regarded as the surface (B).

The spunbonded nonwoven fabric of the present invention preferably has a water absorption rate of 20 seconds or less as measured on the surface (A). By setting the water absorption rate to preferably 20 seconds or less, more preferably 15 seconds or less, and further preferably 10 seconds or less, the non-woven fabric has good performance of removing water adhering to the surface, that is, has excellent water absorption.

The water absorption rate referred to here is measured based on "7.1.1 Drop method" of JIS L1907: 2010 "Water absorption test method for textile products". Drop one drop of water on the spunbonded non-woven fabric, measure the time until it is absorbed and the mirror reflection on the surface disappears, calculate the simple average of the values measured at 10 different points, and use the decimal point as the unit. The value rounded to the first decimal place is taken as the water absorption rate in the present invention.

The basis weight of the spunbonded nonwoven fabric of the present invention is preferably ^{10 to 100 g / m 2.} By setting the basis weight to preferably 10 g / m ² or more, more preferably 13 g / m ² or more, and further preferably 15 g / m ² or more, a spunbonded nonwoven fabric having mechanical strength that can be put into practical use can be obtained. Further, by setting the basis weight to preferably 100 g / m ² or less, more preferably 50 g / m ² or less, a spunbonded nonwoven fabric having appropriate flexibility suitable for use as a nonwoven fabric for sanitary materials can be obtained. ..

The spunbonded nonwoven fabric of the present invention ^{has a texture (g / m 2} ), which is a 20 cm × 25 cm test piece based on “6.2 Mass per unit area” of JIS L1913: 2010 “General nonwoven fabric test method”. , 3 samples are taken per 1 m of width of the sample, each mass (g) in the standard state is weighed, and the mass per ^{1 m 2 calculated from the average value is referred to.}

The spunbonded nonwoven fabric of the present invention may be provided with a hydrophilic agent for the purpose of increasing water absorption. Examples of the type of the hydrophilizing agent include surfactants, and among them, nonionic surfactants are preferable.

The spunbonded nonwoven fabric of the present invention preferably has a non-fused portion thickness (Tu) of 0.5 mm or more. When the Tu is 0.5 mm or more, more preferably 0.7 mm or more, still more preferably 0.9 mm or more, the spunbonded nonwoven fabric has an appropriate cushioning property. On the other hand, when the size is 1.50 mm or less, more preferably 1.40 mm or less, still more preferably 1.30 mm or less, the spunbonded nonwoven fabric has excellent bending flexibility.

The thickness (Tu) of the non-fused portion of the spunbonded nonwoven fabric of the present invention is not particularly limited, but is, for example, the thickness under no load measured by a shape measuring machine (for example, "VR3050" manufactured by KEYENCE CORPORATION). To say.

In the spunbonded nonwoven fabric of the present invention, the ratio (Tu / Tm) of the thickness of the non-fused portion (Tu) to the thickness of the fused portion (Tm) is preferably 2.0 or more, preferably 5.0 or more. Is more preferable, and 10.0 or more is further preferable. When Tu / Tm is 2.0 or more, the difference in density between the periphery of the fused portion and the position separated from the fused portion becomes large, and the circumference of the fused portion becomes large. This is because it is easy to achieve both high water absorption in the high-density part in the above and excellent softness in the low-density part in the remote position. The upper limit is not particularly limited, but is usually 50 or less.

The thickness (Tm) of the fused portion of the spunbonded nonwoven fabric of the present invention is not particularly limited, but for example, a field of view in which a cross section can be observed with a microscope is photographed. Subsequently, using the captured image, the thickness is measured using image analysis software (for example, "WinROOF2015" manufactured by Mitani Corporation). This is measured at 10 arbitrarily extracted points, a simple number average is obtained, the unit is mm, and the value rounded to the third decimal place is the thickness (Tm) of the fused portion of the spunbonded nonwoven fabric in the present invention. be.

Further, the ratio (Tu / Tm) of the thickness of the non-fused portion (Tu) to the thickness of the fused portion (Tm) is obtained by dividing Tu (mm) measured and calculated by the above by Tm (mm). It shall be calculated by rounding off the second decimal place.

[Sanitary material]
The sanitary material of the present invention is at least partially composed of the above-mentioned spunbonded nonwoven fabric. By doing so, a sanitary material having excellent water absorption and quick-drying property can be obtained. The sanitary material of the present invention is mainly a disposable article used for health-related purposes such as medical treatment and long-term care, and examples thereof include disposable diapers, sanitary napkins, gauze, bandages, masks, gloves, adhesive plasters, and the like. The components include, for example, top sheets, back sheets, side gathers and the like of disposable diapers.

Above all, the sanitary material in which the surface (A) of the spunbonded nonwoven fabric is arranged toward the skin side of the wearer can immediately absorb the moisture adhering to the skin surface side into the inside of the spunbonded nonwoven fabric. , It is more preferable because it can reduce discomfort to the wearer.

For example, when the sanitary material is a disposable diaper and the spunbonded non-woven fabric is placed inside the disposable diaper, when the surface (A) is arranged toward the wearer's skin side, sweat or excretion generated during wearing is discharged. The diaper is quickly absorbed and the liquid is rapidly transferred to the surface (B), so that the surface can be kept smooth without excessive dampness.

Further, when the sanitary material is a mask and the spunbonded non-woven fabric is used inside the mask, when the surface (A) is arranged toward the wearer's skin side, sweat and exhalation are condensed and the skin is exposed. Even if moisture adheres to the surface side, it is immediately absorbed inside the spunbonded non-woven fabric and then rapidly transferred to the surface (B), leaving the skin surface smooth without excessive dampness. Can be kept.

[Manufacturing method of spunbonded non-woven fabric]
Next, a preferred embodiment for producing the spunbonded nonwoven fabric of the present invention will be specifically described.

The spunbonded nonwoven fabric of the present invention melts a thermoplastic resin as a raw material, spins it from a spinneret, and then cools and solidifies the yarns obtained by pulling and stretching them with an ejector on a moving net. It is manufactured by the spunbond method, which requires a step of collecting, forming a non-woven fiber web, and then heat-sealing.

As the shape of the spinneret and ejector used, various shapes such as a round shape and a rectangular shape can be adopted. Above all, from the viewpoint that the amount of compressed air used is relatively small and the threads are less likely to be fused or scratched, it is preferable to use a combination of a rectangular base and a rectangular ejector.

In the present invention, the spinning temperature is preferably (melting temperature of the raw material thermoplastic resin + 10 ° C.) or more (melting temperature of the raw material thermoplastic resin + 100 ° C.) or less. By setting the spinning temperature within the above range, a stable molten state can be obtained and excellent spinning stability can be obtained.

The spun yarn is cooled next, but as a method of cooling the spun yarn, for example, a method of forcibly blowing cold air onto the yarn, or natural cooling at the ambient temperature around the yarn. A method of adjusting the distance between the spinneret and the ejector, and the like, or a method of combining these methods can be adopted. Further, the cooling conditions can be appropriately adjusted and adopted in consideration of the discharge amount per single hole of the spinneret, the spinning temperature, the atmospheric temperature and the like.

Next, the cooled and solidified yarn is towed and stretched by the compressed air ejected from the ejector.

In the spunbonded nonwoven fabric of the present invention, it is important to control the average single fiber diameter of the fibers constituting the surface (A) and the surface (B).

The average single fiber diameter of the fiber is determined by the discharge amount and the traction speed per the discharge hole of the spinneret, that is, the spinning speed. Therefore, it is preferable to determine the discharge amount and the spinning speed according to the desired average single fiber diameter.

The spinning speed is preferably 2000 m / min or more, more preferably 3000 m / min or more. By setting the spinning speed to 2000 m / min or more, high productivity can be obtained, and the orientation and crystallization of the fibers can be advanced to obtain high-strength long fibers.

The long fiber yarns stretched by traction in this way are collected by a moving net to form a sheet, and then subjected to a heat fusion process.

As a method for obtaining a fiber having a tortuosity of 1.1 or more on the surface (A) of the spunbonded nonwoven fabric of the present invention, a composite spun fiber using a thermoplastic resin having different characteristics may be used, or depending on the degree of cooling. It is possible to control the degree of bending by forming regions with different stresses on the fiber cross section. In the case of a composite spun fiber, the tortuosity can be increased to 1.1 or more by using a thermoplastic resin having a large melting point difference or a thermoplastic resin having a large viscosity difference. Further, the bending degree can be made 1.1 or more by increasing the difference in cooling conditions between one side surface of the fiber and the opposite side surface.

As a method for obtaining a fiber having a bending degree of 1.1 or less, which is a preferred embodiment of the surface (B) of the spunbonded nonwoven fabric of the present invention, a composite spun fiber using a thermoplastic resin having different properties, a single fiber, or a single fiber is used. Even for single-component spun fibers produced by blending, it is important to equalize the stress borne by the fiber cross section depending on the degree of cooling. Therefore, in the case of a composite spun fiber, the tortuosity can be reduced to 1.1 or less by using a thermoplastic resin having a small melting point difference or a thermoplastic resin having a small viscosity difference. It is also important to cool the fibers uniformly in order to reduce the bending degree to 1.1 or less.

The spunbonded nonwoven fabric of the present invention has a surface (A) and a surface (B) having different fiber diameters. Further, the tortuosity of the fibers constituting the surface (A) is 1.1 or more. As a method for obtaining such a spunbonded nonwoven fabric, for example, from the spinneret for the surface (A), on the fiber web obtained by collecting on the collection net as described above, the downstream side of the collection net. It is possible to adopt a method of depositing fiber webs from the spinneret for the surface (B) arranged in the above and heat-sealing them at once to fix them.

As a method for heat-sealing the spunbonded non-woven fabric of the present invention, in a pair of upper and lower rolls, a heat embossed roll having an engraving (uneven portion) on the surface of one roll and a flat without engraving on the surface of the other roll. Thermal fusion methods using various rolls, such as thermal embossing rolls consisting of a combination of (smooth) rolls and thermal calendar rolls consisting of a combination of upper and lower flat (smooth) rolls, and ultrasonic vibration of the horn. A method by heat fusion such as ultrasonic fusion can be adopted.

When the spunbonded nonwoven fabric of the present invention is produced by heat-sealing with an embossed roll, the fibers on the surface (A) and the surface (B) are fused together at the positions corresponding to the convex portions of the embossed roll. It is preferable because it is easy. Further, by designing the position of the convex portion of the embossed roll, the maximum inscribed circle of the unfused portion can be controlled, which is also a preferable embodiment.

A hydrophilic agent may be added to the spunbonded nonwoven fabric thus obtained before winding. Examples of the method for applying the hydrophilizing agent to the spunbonded non-woven fabric include coating with kiss roll or spray, dip coating, etc., but coating with kiss roll is preferable from the viewpoint of uniformity and ease of controlling the amount of adhesion.

Next, the present invention will be described in detail based on examples. However, the present invention is not limited to these examples. In addition, in the measurement of each physical property, the one without any special description is the one obtained by the measurement based on the above-mentioned method.

(1) Thickness The measurement was performed as described above.

(2) Metsuke Measurement was performed as described above.

(3) The ratio (Da / Db) of the average single fiber diameter (Db) of the surface (B) to the average single fiber diameter (Da) of the surface (A).
For each fiber, fiber samples were randomly collected from the non-woven fiber web collected on the net, and the cross section of the fiber was measured with a scanning electron microscope "S-5500" manufactured by Hitachi High-Technologies Co., Ltd. to obtain one fiber. The image was taken at an observable magnification. Then, as the image analysis software, "WinROOF2015" manufactured by Mitani Corporation was used, and the measurement was performed as described above.

The average single fiber diameter (Da) of the fibers constituting the surface (A) and the average single fiber diameter (Db) of the fibers constituting the surface (B) are measured, the ratio (Da / Db) is calculated, and the decimal point is calculated. The value is rounded off to the second decimal place.

(4) Tortuosity The measurement was performed as described above.

(5) Contact angle of spunbonded non-woven fabric with water The measurement was carried out as described above using a contact angle meter "DMo-501" manufactured by Kyowa Interface Science Co., Ltd.

(6) Presence or absence of fused portion Observation and measurement were performed as described above.

(7) In the water-absorbing and quick-drying spunbonded non-woven fabric, one drop of water is dropped on the surface (A), and after 1 minute has passed, a healthy general adult (15 men and women, 30 people in total) feels the surface. It was touched by hand and evaluated in the following three stages. The average score of the evaluation results was calculated for each non-woven fabric, and the texture of the spunbonded non-woven fabric was used.
5: The surface is smooth and does not feel moisture 3: There is no moisture on the surface, but it is moist 1: The surface is moist and moist (8) Soft feeling Spunbond non-woven fabric is healthy in general Adults (15 males and 15 females, 30 in total) touched it by hand, and the tactile sensation on the surface was evaluated in the following three stages. The average score of the evaluation results was calculated for each non-woven fabric, and the soft feeling of the non-woven fabric was used.

5: Very soft (feels smooth when stroking the surface and feels moderate elasticity in the thickness direction)
3: Not soft 1: I can't feel the softness (I feel a catch when stroking the surface, and I feel a strong repulsion when I press it, or it becomes flat)
[Example 1]
(Fiber web forming surface (A))
Polypropylene (PP) and ethylene copolymerized polypropylene (copolymerized PP) are melted by different extruders to form side-by-side composite fibers (mass ratio 1: 1), and round holes having a hole diameter of 0.4 mm are formed. A single-hole ejection amount of 0.9 g / min was spun from the rectangular cap. After the spun yarn was cooled and solidified, it was pulled and stretched by compressed air having a pressure at the ejector of 0.08 MPa in a rectangular ejector, and collected on a moving net to obtain a non-woven fiber web. .. The average single fiber diameter of the fibers constituting the obtained surface (A) was 18.4 μm.

(Fiber web forming surface (B))
Polypropylene was melted by an extruder and spun from a rectangular mouthpiece having a round hole having a hole diameter of 0.4 mmφ at a single hole discharge rate of 0.3 g / min. After the spun yarn is cooled and solidified by cold air, it is pulled and stretched by compressed air having a pressure at the ejector of 0.08 MPa in a rectangular ejector to form a surface (A) on a moving net. Collected on the textile web. The average single fiber diameter of the fibers constituting the obtained surface (B) was 10.6 μm.

(Spanbond non-woven fabric)
The laminated fiber web thus obtained is made of metal on the lower roll by using a metal embossed roll arranged in a so-called quilting pattern, which is a lattice pattern in which a straight line pattern formed by a perfect circular convex portion is orthogonal to the upper roll. Using an embossed roll having a pair of upper and lower heating mechanisms composed of flat rolls, heat fusion is performed at a linear pressure of 300 N / cm and a heat fusion temperature of 125 ° C., and a grain size of 40 g / m ² . A spunbonded non-woven material was obtained. Then, as a hydrophilic treatment, a nonionic surfactant was applied to the nonwoven fabric using kissroll so that the active ingredient was 0.5 wt% with respect to the weight of the spunbonded nonwoven fabric.

Table 1 shows the evaluation results of the obtained spunbonded non-woven fabric.

[Example 2]
A spunbonded nonwoven fabric was obtained in the same manner as in Example 1 except that a metal embossed roll in which regular circular protrusions were staggered at the same pitch in both directions of MD and CD was used for the upper roll.

[Example 3]
A spunbonded nonwoven fabric was obtained in the same manner as in Example 2 except that the single-hole discharge rate of the fiber web forming the surface (A) was 0.53 g / min.

[Example 4]
A spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the linear pressure was heat-sealed at 10 N / cm using an embossed roll.

[Example 5]
Examples except that the fiber web forming the surface (B) was melted with polypropylene and ethylene copolymer polypropylene by different extruders and spun out as side-by-side composite fibers (mass ratio 1: 1). A spunbonded nonwoven fabric was obtained in the same manner as in 1.

[Comparative Example 1]
The fiber web constituting the surface (A) and the fibers and fiber webs constituting the surface (B) each have a single-hole discharge rate of 0.6 g / min, and ethylene copolymer polypropylene and the same ethylene copolymer polypropylene are used. A spunbonded nonwoven fabric was obtained in the same manner as in Example 1 except that it was melted and spun by another extruder.

Table 2 shows the evaluation results of the obtained spunbonded non-woven fabric.

[Comparative Example 2]
Instead of heat-sealing using an embossed roll, a spunbonded nonwoven fabric was obtained by the same method as in Example 1 except that the obtained fiber web was heated with hot air at 150 ° C. and heat-sealed. In the fusion with hot air, although the adjacent fibers are fused to each other, the "fused portion" in which the fibers on the surface (A) and the fibers on the surface (B) are fused is not formed.

[Comparative Example 3]
The fiber web forming the surface (A) was melted with ethylene copolymer polypropylene and the same ethylene copolymer polypropylene with different extruders, and spun out as side-by-side composite fibers (mass ratio 1: 1). A spunbonded nonwoven fabric was obtained in the same manner as in Example 1 except for the above.

In Examples 1 to 5, the average single fiber diameter ratio (Da / Db) is large, the bending degree of the surface (A) is large, and the fibers of the surface (A) and the fibers of the surface (B) are fused together. It can be seen that it has an excellent water absorption and quick-drying property and an excellent soft feeling because it has a place where it is used.

On the other hand, in Comparative Example 1, since the average single fiber diameter ratio is small, moisture is not transferred to the surface (B) side in the non-woven fabric, and the water absorption and quick-drying property are inferior. Further, in Comparative Example 2, since the fibers on the surface (A) and the fibers on the surface (B) do not have a place where both of them are fused, it is difficult for water to move into the surface, and the water absorption and quick-drying performance. Is inferior. In Comparative Example 3, since the bending degree of the surface (A) was small, it was difficult to obtain a water absorption rate, the water absorption and quick-drying performance was not sufficient, and the soft feeling was also inferior.

1: Spun-bonded non-woven fabric 11: Fused portion 12: Non-fused portion 13: Maximum inscribed circle of non-fused portion

Claims

It has a fused portion and a non-fused portion, and the ratio (Da) of the average single fiber diameter (Da) of the fibers on one surface (A) to the average single fiber diameter (Db) of the fibers on the other surface (B). / Db) is 1.1 or more, the contact angle between the surface (A) and the surface (B) with water is both 30 ° or less, and the bending degree of the fiber on the surface (A) is 1. .Spunbonded non-woven fabric that is 1 or more.
The spunbonded nonwoven fabric according to claim 1, wherein the diameter of the maximum inscribed circle of the non-fused portion is 2.0 mm or more.
The spunbonded nonwoven fabric according to claim 1 or 2, wherein the thickness (Tu) of the spunbonded nonwoven fabric in the non-fused portion is 0.5 mm or more.
Claims 1 to 3 in which the ratio (Tu / Tm) of the thickness (Tu) of the spunbonded nonwoven fabric in the non-fused portion to the thickness (Tm) of the spunbonded nonwoven fabric in the fused portion is 2.0 or more. The spunbonded non-woven fabric described in any of the above.
The spunbonded nonwoven fabric according to any one of claims 1 to 4, wherein the fiber of the surface (B) has a tortuosity of 1.1 or less.
A sanitary material that is at least partially composed of the spunbonded nonwoven fabric according to any one of claims 1 to 5.
The sanitary material according to claim 6, wherein the surface (A) is arranged toward the skin side of the wearer.