WO2023013790A1

WO2023013790A1 - Nonwoven fabric for hygiene and method for producing same

Info

Publication number: WO2023013790A1
Application number: PCT/JP2022/030248
Authority: WO
Inventors: 奈都美小林; 裕太寒川
Original assignee: 花王株式会社
Priority date: 2021-08-06
Filing date: 2022-08-08
Publication date: 2023-02-09
Also published as: TW202321037A; JP2023024412A; CN116964263A

Abstract

A nonwoven fabric for hygiene according to the present invention comprises a fiber assembly which contains fibers that contain a polyamide resin, while having fusion points where the constituent fibers of the fiber assembly are fused with each other. This nonwoven fabric for hygiene has a volume filling rate of 3.5% or more. It is preferable that the constituent fibers are sheath-core composite fibers wherein the core is formed of a polyamide resin, while the sheath is formed of a high-density polyethylene resin. In a production method according to the present invention, a web of composite fibers that contain a polyamide resin is subjected to an air-through treatment, thereby obtaining a fiber assembly, and the fiber assembly is consolidated by being heated at a temperature that is not more than the melting point of the resin that constitutes the fiber assembly.

Description

Sanitary nonwoven fabric and its manufacturing method

The present invention relates to a sanitary nonwoven fabric and a method for producing the same.

There have been proposed fibers and articles that have a configuration that allows the user to perceive a cold sensation. For example, Patent Literature 1 discloses a comfortable fabric intended to be used in clothing for eliminating hot feeling in summer. This fabric contains at least one type of organic polymer fiber having a thermal conductivity of 5 W/mK or more in the fiber axis direction at 20° C. to 30° C., and a thermal conductivity in the thickness direction of the fabric at 20° C. to 30° C. is 0.5 W/mK or more. The document also discloses that the contact coldness is 0.13 W/cm ² or more at 08 W/mK or more.

Patent Document 2 discloses an absorbent article in which a cooling sensation agent is applied to side flaps extending outward from both sides in the lateral direction of an absorbent body.

In Patent Document 3, for the purpose of expressing hygroscopicity and cool contact feeling, the sheath polymer is composed of polyamide, the core polymer is composed of polyether ester amide copolymer, and the amount of inorganic particles is 0.1 in the whole fiber. Fibers containing ∼5% by weight and fabrics using the same are disclosed.

In addition, Patent Document 4 discloses a knitted fabric made by knitting yarns of composite fibers having a sheath layer made of polyethylene and a core layer made of nylon or polyester.

Japanese Patent Application Laid-Open No. 2010-236130 JP 2016-120208 A US2017/0342606A1 Utility Model Registration No. 3226090

TECHNICAL FIELD The present invention relates to a sanitary nonwoven fabric comprising a fiber assembly containing fibers containing a polyamide resin.
In one embodiment, the fiber assembly preferably has a fusion point where the constituent fibers are fused together.
In one embodiment, the volume filling rate of the fiber assembly containing fibers containing polyamide resin is preferably 3.5% or more.

The present invention also relates to a method for producing a sanitary nonwoven fabric, which includes a step of air-through processing or spunbonding a fiber web containing a polyamide resin.

Detailed description of the invention

Sanitary products such as sanitary napkins, panty liners, and other absorbent articles used to absorb fluids discharged from the body, as well as sanitary products such as eye masks that cover the eyes and face masks that cover the mouth and nose, are non-woven fabrics. When such an article touches the skin before use or during wearing, the wearer perceives a warm sensation, which may cause discomfort such as stuffiness during use. be. This can be particularly noticeable in hot environments. Therefore, it is desired that the part of the sanitary product that comes into contact with the skin has a good texture and a structure that gives a cool feeling.

However, the techniques described in Patent Documents 1, 2, and 4 are applied to articles other than sanitary goods such as clothing, and application to sanitary goods has not been considered at all.

Since the technology described in Patent Document 3 uses a cooling agent, it is slow-acting to perceive a cooling sensation, and it is difficult to feel a cooling sensation when contact is made with thick skin such as the palm of the hand.

Therefore, the present invention relates to a sanitary non-woven fabric that has a good feel and allows the user to perceive a cool sensation when touching the skin.

The present invention will be described below based on its preferred embodiments.
The sanitary nonwoven fabric of the present invention is suitably used as a constituent member of sanitary goods. Typical examples of sanitary products are sanitary products such as face masks and eye masks, and absorbent products such as disposable diapers and sanitary napkins that absorb body fluids such as urine and menstrual blood. It is a sexual item.
Sanitary nonwoven fabrics are placed on the skin-contacting side, which is the surface that contacts the wearer's skin when the sanitary product is worn, or on the part that touches the wearer's hands, etc. when handling the sanitary product. or
Sanitary non-woven fabrics are applicable without being particularly limited to the uses described herein.

The sanitary non-woven fabric of the present invention is a sheet-like article provided with a fiber aggregate containing fibers containing polyamide resin (hereinafter also referred to as "polyamide fiber-containing aggregate"). The sanitary non-woven fabric may be composed of fibers containing polyamide resin alone or mixed with other fibers to form a fiber aggregate consisting of a single fiber layer. Alternatively, the nonwoven fabric for sanitary use is made by laminating a layer of fiber aggregates containing fibers containing polyamide resin and a layer of fiber aggregates other than the layer of fiber aggregates containing polyamide resin. It may be configured as a fiber aggregate consisting of layers.

The constituent fibers of the sanitary nonwoven fabric of the present invention maintain the form of the fiber sheet by fusion. Specifically, from the viewpoint of further improving texture and breathability, the constituent fibers of the sanitary nonwoven fabric have fusion points where these fibers are fused together.
Fusion bonding is a mode in which only heat or heat and pressure are applied to a plurality of fibers to melt the fibers, thereby obscuring the boundaries between the fibers. In order to have a fusion point, it can be formed by blowing hot air onto the fiber web, as will be described later.

The fibers contained in the sanitary nonwoven fabric contain polyamide resin as described above. Modes of presence of the polyamide resin in the constituent fibers contained in the sanitary nonwoven fabric of the present invention include (i) a mode in which the constituent resin of the fiber is only a polyamide resin, and (ii) a resin component composed of a polyamide resin and the resin component. fibers containing a second resin component different from the above.

In general, polyamide resins have relatively low rigidity among organic polymer materials and have good workability, so they have been widely used for fabric products. Fibers containing polyamide resin have hygroscopicity and relatively high thermal conductivity among organic polymer materials. The inventors of the present invention focused on the above-described characteristics of the polyamide resin, and by incorporating the polyamide resin into the constituent fibers of the nonwoven fabric, the high thermal conductivity of the polyamide resin itself is exhibited, and the fibers are made to exhibit flexibility. As a result, it has been found that the nonwoven fabric can exhibit both a good texture and a cool sensation.

Specific examples of (i) include fibers composed of only a single type of polyamide resin as the constituent resin, and fibers composed of a plurality of types of polyamide resins as the constituent resin. The latter embodiment includes, for example, a fiber in which the outer surface and the inside of the fiber are made of different types of polyamide resins.
Specific examples of (ii) include (a) a fiber made of a resin in which a polyamide resin and another resin are mixed, and (b) a core made of a polyamide resin and a sheath covering the surface of the core made of another resin. or (c) side-by-side having a polyamide resin and another resin, wherein the other resin is continuously present along the length direction of the fiber on at least a part of the surface of the fiber made of the polyamide resin Composite fiber etc. are mentioned. In this case, the other resin is preferably a resin component other than the polyamide resin and has a melting point lower than that of the polyamide resin from the viewpoint of facilitating the formation of fusion points.
The fibers used in the present invention may be solid or hollow. Solid fibers are preferred from the viewpoint of enhancing thermal conductivity and making it easier for the wearer to perceive a cool sensation.

As the presence of the constituent resin in the fiber, it is preferably a conjugate fiber containing a polyamide resin, more preferably a conjugate fiber containing a polyamide resin inside the fiber, and at least the entire outer surface of the fiber is covered with other resins. More preferably, it is a conjugate fiber containing a polyethylene resin, and more preferably a conjugate fiber having a core-sheath structure in which the core is a polyamide resin and the sheath is a polyethylene resin.
Since polyethylene resin has a higher thermal conductivity than polyamide resin, the structure having polyethylene resin on the fiber surface directly contacts the wearer's skin, so that the wearer feels cool. It is possible to strongly perceive the feeling. In addition, good properties such as high thermal conductivity, low rigidity, and hygroscopicity possessed by the polyamide resin can be exhibited in the fiber, and the texture of the nonwoven fabric is further improved.

In addition, by using it together with resins with different melting points, it is possible to form a nonwoven fabric without completely fusing the fibers together, improving workability during manufacturing and improving the texture of the resulting nonwoven fabric. In addition, crimps can be developed in the conjugate fibers to further enhance the texture. In addition, the nonwoven fabric has a smooth feel, and even if the user perceives a cold sensation when touching the nonwoven fabric, it is possible to prevent the user from feeling an unpleasant wet feeling.

Examples of polyamide resins used in the present invention include nylon 6, nylon 66, and aromatic nylon. From the viewpoint of ease of fiber formation, it is preferable to use nylon 6 as the polyamide resin.

Examples of the polyethylene resin used in the present invention include low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), high-density polyethylene resin (HDPE), linear low-density polyethylene resin (LLDPE), and ethylene - propylene copolymers and the like. These can be used singly or in combination.

From the viewpoint of having a high thermal conductivity and allowing the wearer to perceive a stronger cooling sensation, it is preferable that HDPE is included as the polyethylene resin, and it is more preferable to use only HDPE. That is, it is more preferable to use HDPE alone as the polyethylene resin. In particular, by disposing HDPE on the surface of the fibers, it is advantageous in that fusion points between the fibers can be formed more easily in the manufacturing method described later.

More specifically, it is more preferable to use a composite fiber having a core-sheath structure in which the core is made of polyamide resin and the sheath is made of HDPE. As a result, even if the polyamide resin absorbs moisture resulting from bodily fluids such as sweat, urine, menstrual blood, and exhaled breath, the polyamide resin does not come into direct contact with the wearer's skin, thereby preventing unpleasant dampness. In addition, since it is possible to facilitate fusion bonding only at the intersections of the fibers during manufacturing, the tactile sensation is improved. As a result, the sanitary nonwoven fabric maintains a good texture, and has a smooth surface with a good tactile feel, allowing the wearer to perceive a comfortable cool sensation.

Further, as a preferred embodiment of the present invention, when a sanitary nonwoven fabric is produced by an air-through method, for example, by using a core-sheath composite fiber composed of a sheath-constituting resin having a lower melting point than a core-constituting resin, In addition, problems such as failure to maintain the shape of the fiber due to excessive melting of the constituent resin of the fiber and formation of holes in the resulting nonwoven fabric are less likely to occur, thereby further improving the stability of production. In addition, by subjecting the above-mentioned core-sheath composite fiber to the air-through method, it becomes easier to fuse only the intersections of the fibers, and it is possible to form a nonwoven fabric without completely fusing the fibers, and the texture is further improved. A nonwoven fabric is obtained. In addition, the nonwoven fabric has a smooth feel, and even if the user perceives a cold sensation when touching the nonwoven fabric, it is possible to prevent the user from feeling an unpleasant wet feeling.

Examples of resins other than the resins that can be used in the present invention include polyolefin resins other than polyethylene resins such as polypropylene (PP) and polybutene, polyester resins such as polyethylene terephthalate (PET), and vinyl-based resins such as polyvinyl chloride and polystyrene. Various thermoplastic fibers such as resins, acrylic resins such as polyacrylic acid and polymethyl methacrylate, and fluororesins such as polyperfluoroethylene can be used. These resins can be used singly or in combination of two or more as needed.

The content of the polyamide resin relative to the total mass of the fibers contained in the sanitary nonwoven fabric of the present invention is preferably 25% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, and preferably 100% by mass. % or less, more preferably 90 mass % or less, and still more preferably 80 mass % or less.
When polyethylene resin is contained in the constituent fibers, the content of polyethylene resin relative to the total mass of fibers contained in the sanitary nonwoven fabric is preferably 30% by mass or more, more preferably 40% by mass or more, and preferably 90% by mass or less. , more preferably 80% by mass or less.
It is also preferable that the content of each resin described above is satisfied in the polyamide fiber-containing assembly.

When polyethylene resin is contained in the constituent fibers, the mass ratio of the polyamide resin to the polyethylene resin contained in the nonwoven fabric for sanitary use of the present invention (polyamide resin/polyethylene resin) is from the viewpoint of expressing both a cool feeling and excellent texture. , preferably 0.1 or more, more preferably 0.2 or more, still more preferably 0.3 or more, and from the viewpoint of nonwoven fabric processability, preferably 2.0 or less, more preferably 1.5 or less, and still more preferably is less than or equal to 1.3.
It is also preferred that the mass ratios mentioned above are satisfied within the assembly containing polyamide fibers.

The type of the constituent resin in the fiber is determined by confirming the melting point of the resin constituting the fiber by differential scanning calorimetry, and by using one or more of infrared spectroscopy (IR) and nuclear magnetic resonance (NMR). to confirm. In addition, using a scanning electron microscope (SEM), the spinning method is estimated from the surface shape and cross-sectional shape of the fiber, and the type of resin in the fiber is specified.
For the content of the constituent resin, first, the mass of the nonwoven fabric to be measured and the thickness under no load are measured. After that, the fiber structure is fixed using liquid nitrogen or the like, a cross section of the nonwoven fabric is created so that the fiber cross section can be observed in a direction orthogonal to the longitudinal direction of the fiber, and the volume ratio is confirmed using an SEM or the like. The content of the resin is calculated from the obtained volume ratio and the specific gravity of the resin. When the nonwoven fabric to be measured is incorporated in sanitary goods, the nonwoven fabric is peeled off from the sanitary goods by cold spray and subjected to the measurement.

From the viewpoint of reducing the content of air, which has a low thermal conductivity, and improving the thermal conductivity of the nonwoven fabric, the volume filling rate of the aggregate containing polyamide fibers is preferably 3.5% or more, more preferably 7.0. % or more, more preferably 10.0% or more, still more preferably 12.0% or more, and even more preferably 14.0% or more.
When used as a disposable sanitary material that comes into contact with the wearer's skin, the volume filling ratio of the polyamide fiber-containing aggregate is preferably 60.0% or less, more preferably 50.0%, from the viewpoint of improving the texture. It is 0% or less, more preferably 45.0% or less, even more preferably 35.0% or less, still more preferably 30.0% or less.
Therefore, the volume filling rate of the polyamide fiber-containing assembly is preferably 3.5% or more and 60.0% or less, more preferably 7.0% or more and 50.0% or less, and still more preferably 10.0% or more and 45.0% or less. It is 0% or less, more preferably 12.0% or more and 35.0% or less, and still more preferably 14.0% or more and 30.0% or less.

Since the polyamide fiber-containing assembly has the above-described volume filling rate, the content of air with low thermal conductivity is reduced in the sanitary nonwoven fabric, so that the heat transferability can be increased. As a result, the wearer can be made to perceive a cold sensation more strongly.
In addition to this, the sanitary nonwoven fabric of the present invention and sanitary products incorporating the nonwoven fabric can exhibit a sufficient texture.
The configuration described above can be obtained, for example, by subjecting the fiber assembly obtained in the manufacturing process of the sanitary nonwoven fabric to a consolidation treatment or the like, as in the manufacturing method described later.

The volume filling factor in the present invention can be expressed as a percentage of apparent volume to actual volume. Specifically, a predetermined area of the sanitary nonwoven fabric to be measured is cut to obtain a measurement sample, and the mass (g) of the sample is measured. The predetermined area for cutting out the measurement sample is preferably 10 cm square. Cut to the width and length that gives the largest area. Then, the basis weight A (g/cm ² ) of the measurement sample is calculated.
Moreover, the method for measuring the thickness B (cm) of the measurement sample is as follows. First, only a 12.59 g (55 mm diameter) plate is placed on a laser displacement meter (LK-080 manufactured by Keyence Corporation. All laser displacement meters in this specification are this.) The thickness measured is set to zero and the zero point is adjusted. Then, the plate is placed on the measurement sample, and the thickness in that state is measured using a laser displacement meter, and this is defined as the thickness B (cm) of the measurement sample. In measuring the thickness B, a load of 4.9 mN/cm ² was applied to the measurement sample by placing the plate.

Then, using the specific gravity C (g/cm ³ ) of the constituent components of the fiber, the volumetric filling rate (%) is calculated from the following formula (I). In the case of fibers containing two or more kinds of resins such as conjugate fibers, the specific gravity C is the sum of the specific gravities based on the mass ratio of each component. For example, when a bicomponent fiber is included in which a component having a specific gravity C1 (g/cm ³ ) and a component having a specific gravity C2 (g/cm ³ ) are in a mass ratio of 30:70, the specific gravity C (g/cm ³ ) is calculated as “0.3×specific gravity C1+0.7×specific gravity C2”.
Volume filling rate (%) = 100 x (A)/(B x C) (I)

If the sanitary nonwoven fabric to be measured is incorporated into a sanitary product such as an absorbent article, apply a cold spray to the sanitary product to solidify the hot-melt adhesive, and then carefully remove the sanitary nonwoven fabric to be measured. peel off. Also, in the case where it is joined to another member such as a second fiber assembly to be described later by fusion, similarly, after fixing the structure using cold spray, liquid nitrogen, etc., the measurement target is peeled off and measured. do. This means is also common to other measurements in this specification.

The sanitary nonwoven fabric of the present invention has a friction coefficient mean deviation (MMD) measured by the following method of preferably 0.010 or less, more preferably 0.009 or less, and still more preferably 0.008 or less, 0.004 or more is realistic. With such a structure, the surface of the nonwoven fabric becomes smooth to the touch, and the nonwoven fabric has a good texture and a high usability.
The coefficient of friction described above is preferably satisfied when a polyamide fiber-containing aggregate is targeted.

The average deviation MMD of the coefficient of friction is measured using KES-FB4-AUTO-A (trade name) manufactured by Kato Tech Co., Ltd.
First, a test piece of 20 cm×20 cm is taken out from the sanitary nonwoven fabric to be measured. If a test piece of this size cannot be taken out, the size of the test piece may be changed as appropriate. Then, in this test piece, the surface on which the fiber assembly containing the polyamide resin is arranged is specified by a method such as infrared spectroscopy (FT-IR).
The specimen is then mounted on a smooth metal flat test stand. The contact surface of the contact is pressed against the surface of the fiber assembly of the test piece with a force of 49 cN, and the test piece is horizontally moved 2 cm at a constant speed of 0.1 cm/sec. A uniaxial tension of 7.3 cN/cm is applied to the specimen. The contact is made by bending 20 pieces of piano wire with a diameter of 0.5 mm into a U shape with a width of 10 mm. The contact is pressed against the test piece with a force of 49 cN by a weight.
This measurement is performed both in one direction (MD direction) of the nonwoven fabric and in a direction perpendicular to the direction (CD direction) to obtain MMD _MD and MMD _CD , and the average value is obtained from the following formula (II), and this is the friction Let MMD be the average deviation of the coefficients. If the test piece of the sample can only be taken out in either the MD direction or the CD direction, the value in only one direction is taken as the mean deviation MMD of the friction coefficient.
Mean deviation of coefficient of friction MMD={(MMD _MD ² +MMD _CD ² )/2} ^1/2 (II)

The sanitary nonwoven fabric of the present invention preferably has a total thickness of 0.05 mm or more, more preferably 0.08 mm or more, from the viewpoint of improving the texture of the nonwoven fabric.
In addition, the sanitary nonwoven fabric of the present invention has a thickness of preferably 8 mm or less, more preferably 7.5 mm or less, and further preferably 8 mm or less, more preferably 7.5 mm or less, from the viewpoint of reducing the air content in the nonwoven fabric and increasing the thermal conductivity. Preferably, it is 7 mm or less.
The thickness of the sanitary nonwoven fabric described above is measured using a laser displacement meter or the like under a load of 4.9 mN/cm ² (0.5 gf/cm ² ).
To efficiently produce a sanitary nonwoven fabric capable of efficiently making a wearer perceive a cold sensation by increasing the heat capacity of the sanitary nonwoven fabric, because the thickness of the sanitary nonwoven fabric of the present invention is configured as described above. can be done.
From the same point of view, it is also preferable that the polyamide fiber-containing assembly satisfies the thickness range described above under a load of 4.9 mN/cm ² (0.5 gf/cm ² ).

In the sanitary nonwoven fabric of the present invention, the cool contact q _max of the polyamide fiber-containing aggregate is preferably 0.06 W/m ² or more, more preferably 0.08 W/m ² or more, and still more preferably 0.10 W/m. ² or more, preferably 0.80 W/m ² or less, more preferably 0.60 W/m ² or less, and even more preferably 0.50 W/m ² or less.
Specifically, the cool contact q _max of the polyamide fiber-containing assembly of the sanitary nonwoven fabric is preferably 0.06 W/m ² or more and 0.80 W/m ² or less, more preferably 0.08 W/m ² or more and 0 0.60 W/m ² or less, more preferably 0.10 W/m ² or more and 0.50 W/m ² or less.

The cool contact q _max can be measured, for example, by the following method. First, a test piece having a size of 10 cm long×10 cm wide is cut out from the sanitary nonwoven fabric to be measured, and the test piece is left for 24 hours in an environment of room temperature of 23° C. and relative humidity of 50%. If it is not possible to cut out the test piece with the above dimensions, cut the test piece with as large a dimension as possible so as to have dimensions close to the above dimensions.
Next, under this environment, the test piece is placed on the measuring table, and the test piece is fixed to the measuring table using double-sided tape. As the measuring table, one that is set to 23° C. by a constant temperature device using gas or liquid as a heat medium is used.
Subsequently, the cooling sensation q _max of the object to be measured is measured according to the measurement device (KES-F7 Thermolab II, manufactured by Kato Tech Co., Ltd.) and the measurement manual of the device. Specifically, a pure copper plate with an area of 9.0 cm ² and a mass of 9.8 g was used as a hot plate to be brought into contact with the object to be measured, and the initial temperature of the copper plate was set to 33°C (a temperature 10°C higher than the surface temperature of the object to be measured). , The contact pressure of the copper plate to the object to be measured is set to 1 kPa, the copper plate is brought into contact with the test piece, the value of the heat flow at the moment of contact is set to zero, and the maximum value of the heat flow is measured. This measurement is performed 5 times for the surface to be measured, and the arithmetic average value of the plurality of measured values is taken as the cool contact sensation q _max (W/m ² ) of the measurement object.

The cool contact sensation is a quantified skin sensation that feels cold when the skin touches an object. This cool contact feeling varies depending on the amount of heat transferred from the skin to the object when the skin touches the object. The cool contact q _max corresponds to the maximum amount of heat transferred from _the skin to the object. becomes smaller as the case may be. Therefore, when the value of the contact coolness q _max is within the above range, the coolness can be perceived more effectively.

In the sanitary nonwoven fabric of the present invention, it is preferable that the fibers constituting the nonwoven fabric are arranged with a certain orientation.
With such a configuration, heat transfer easily occurs along the fiber length direction, making it easier for the wearer to perceive a cool sensation.

More specifically, in the sanitary nonwoven fabric of the present invention, when the nonwoven fabric is left standing on a horizontal surface, the fiber length direction of the fibers of the nonwoven fabric is preferably substantially parallel to the horizontal surface.
In addition to or instead of this, it is preferable that the fibers extend in one direction when the sanitary nonwoven fabric is viewed from above. For example, in a plan view of the sanitary nonwoven fabric, when considering the first direction of the sanitary nonwoven fabric and the second direction orthogonal to the first direction, the extending direction of the fibers is the first direction or the second direction of the nonwoven fabric. It is more preferable that the When fibers have crossing points, it is desirable that 50% or more of the sanitary nonwoven fabrics have an obtuse angle formed by the crossing fibers in a plan view. An obtuse angle refers to an angle greater than 90°.

Quantification of the angle between fibers is performed by photographing arbitrary 3 points of the sanitary nonwoven fabric with a SEM at a magnification that allows about 10 fiber intersections to be confirmed within the field of view, and the obtained image data is attached to the SEM or It is possible to measure and tabulate using arbitrary image analysis software or the like. If you do not have image analysis software, you can print the image data, check it with an angle measuring device such as a protractor, write it on a data sheet, and tabulate it.
By having at least one configuration related to the orientation of the fibers described above, it becomes easier for heat to move in a certain direction, and it is possible to make it easier for the wearer to more effectively perceive a cool sensation.
In such a configuration, for example, a long sheet is produced using short fibers containing a polyamide resin as a material, the long sheet is conveyed while applying tension in the conveying direction, and the fibers are fused together by an air-through method. Alternatively, it can be obtained by a method in which fibers containing a polyamide resin are conveyed in one direction while being spun on conveying equipment such as a belt conveyor.

In the sanitary nonwoven fabric of the present invention, the polyamide fiber-containing aggregate preferably has a thermal conductivity of 0.08 W/mK or more, more preferably 0.10 W/mK or more, and still more preferably 0.13 W/mK or more. The thermal conductivity described above can be measured by, for example, melting a sanitary nonwoven fabric and making it into a film-like sample having a thickness of about 1 mm. A detailed measurement method will be described later.
By having such a thermal conductivity, it is possible to make the wearer of the sanitary article containing the sanitary nonwoven fabric perceive a stronger cooling sensation.

In the above description, for convenience of explanation, the sanitary nonwoven fabric is an aspect having a single fiber layer containing fibers containing polyamide resin (regardless of whether it is composed of a single fiber or mixed with other fibers). ) has been described as an example, but the present invention is not limited to this form. Another embodiment of the sanitary nonwoven fabric of the present invention is described below.

As another embodiment of the sanitary nonwoven fabric, for example, a layer of fiber aggregates containing first fibers containing a polyamide resin (hereinafter also referred to as a "first fiber layer") and a layer adjacent to the fiber layer. and a layer of a fiber aggregate containing second fibers containing fibers other than the first fibers (hereinafter also referred to as "second fiber layer"). In other words, this embodiment is a sanitary nonwoven fabric having a multilayer structure. Adjacent here means that the fiber layers are adjacent to each other without interposing another fiber layer, and it is permissible that an adhesive is interposed between the fiber layers.
In this case, the first fiber layer preferably constitutes the outer surface of the sanitary nonwoven fabric from the viewpoint of effectively perceiving a cool sensation. Moreover, from the same point of view, at least the first fiber layer preferably satisfies the above-described various preferred aspects of the sanitary nonwoven fabric, and more preferably the entire sanitary nonwoven fabric satisfies the above preferred aspects.

Specifically, a sanitary nonwoven fabric having a multi-layer structure is, for example, a state in which a fiber web containing first fibers containing a polyamide resin and a second fiber web containing fibers other than the first fibers are laminated, and then air-through processed or It can be obtained by spunbonding. In this case, the boundaries between the fiber layers are generally unclear, but may include portions where the boundaries are clear. In the case of this form, each fiber layer maintains the form of a fiber sheet by at least one of entanglement, fusion bonding, and compression bonding, for example.
In still another embodiment of a sanitary nonwoven fabric having a multilayer structure, a fibrous web or fibrous sheet containing first fibers containing a polyamide resin and a fibrous web or fibrous sheet containing fibers other than the first fibers are bonded together with an adhesive. A mode in which the form of the fiber sheet is maintained by adhering and joining is exemplified. In this case, the boundaries of each fiber layer are generally clear.

In any aspect, the fibers other than the first fibers include fibers containing the above-described constituent resins such as PET resin and PP resin, as well as pulp fibers, rayon fibers, and other hydrophilized fibers. One or more types are mentioned.

The basis weight of the first fiber layer is preferably 10 g/m ² or more, more preferably 15 g/m ² or more, still more preferably 18 g/m ² or more, from the viewpoint of sufficiently perceiving a cool sensation. is 200 g/m ² or less, more preferably 150 g/m ² or less, still more preferably 100 g/m ² or less.
The basis weight of the second fiber layer is preferably 10 g/m ² or more, more preferably 15 g/m ² or more, still more preferably 20 g/m ² or more, more preferably 140 g/m ² or less, more preferably 90 g/m 2 or more. ² or less, more preferably 70 g/m ² or less.

When the sanitary nonwoven fabric has a multilayer structure, the thermal conductivity of the fiber layer containing the first fibers containing the polyamide resin is preferably 0.11 W/mK or more, more preferably 0.13 W/mK or more, and even more preferably 0.15 W/mK or more. The use of fibers having such a thermal conductivity is preferable because the range of thermal conductivity for sanitary nonwoven fabrics can be achieved.
Moreover, the above-described thermal conductivity of the constituent fibers can be achieved by using composite fibers containing polyamide resin and polyethylene resin as constituent fibers, for example.

Thermal conductivity can be measured, for example, by the following method. First, the nonwoven fabric or fiber to be measured is separated from the product by using a cold spray or the like, or by collecting the fiber. Next, the separated nonwoven fabric or fiber is introduced into a heating and pressurizing equipment such as a press, and is heated and pressed at a temperature higher than the melting point of the nonwoven fabric or fiber raw material to form a film sample having a thickness of about 1 mm. At this time, the pressurization conditions are appropriately adjusted so that no air remains in the sample.
Then, using a constant thermal conductivity measuring device (manufactured by Kato Tech Co., Ltd., KES-F7 Thermolab II), the amount of heat transferred in a steady state from the hot plate at 33 ° C. to the hot plate at 23 ° C. through the sample. The thermal conductivity is measured based on This measurement is performed at three points for one film-like sample, and the highest thermal conductivity value among these is taken as the thermal conductivity (W/mK) in the present invention.
When the measurement object is a sanitary nonwoven fabric with a multilayer structure, the fiber layer on the side with the highest value of the above-mentioned cool contact q _max is set as the first fiber layer, and the thermal conductivity of the fiber layer is measured as described above. Offer to

When the sanitary nonwoven fabric of the present invention includes a second fiber layer, from the viewpoint of reducing the content of air with low thermal conductivity and improving the thermal conductivity of the nonwoven fabric, the first fiber of the sanitary nonwoven fabric The volume filling factor in the layer is preferably 3.5% or more, more preferably 7.0% or more, still more preferably 10.0% or more, still more preferably 12.0% or more, and still more preferably 14.0% or more. 0% or more.
When used as a disposable sanitary material that comes into contact with the wearer's skin, the volume filling rate of the first fiber layer of the sanitary nonwoven fabric is preferably 60.0% or less, more preferably 60.0% or less, more preferably, from the viewpoint of improving the texture. is 50.0% or less, more preferably 45.0% or less, even more preferably 35.0% or less, still more preferably 30.0% or less.
By having such a configuration, it is possible to increase heat transferability, and as a result, it is possible to make the wearer perceive a colder sensation more strongly. In addition to this, the sanitary nonwoven fabric of the present invention and sanitary products incorporating the nonwoven fabric can exhibit a sufficient texture.
In the measurement of the volume filling factor of the first fiber layer, the fiber layer on the surface side with the highest value of the above-mentioned cool contact q _max is taken as the first fiber layer, and this fiber layer is subjected to the measurement of the above-mentioned volume filling factor.

In the case where the sanitary nonwoven fabric includes the above-mentioned second fiber layer, it is preferable that the thickness change of the second fiber layer is a predetermined value or more.
Specifically, the amount of compressive deformation of the second fiber layer under a load of 9.8 mN/cm ² (1 gf/cm ² ) is preferably 0.3 mm or more, more preferably 0.5 mm or more. Further, the amount of compressive deformation of the second fiber layer under the same load is preferably 3 mm or less. As will be described later, the amount of compression deformation is the amount of change obtained by subtracting the thickness of the second fiber layer under a load of 9.8 mN/cm ² (1 gf/cm ² ) from the thickness of the second fiber layer under no load. is represented as The compression deformation amount can be calculated by a method described later.
With such a configuration, when the first fiber layer comes into contact with the wearer, the first fiber layer easily deforms following the deformation of the second fiber layer, thereby making contact with the wearer. By increasing the area, it is possible to make the wearer perceive a cold feeling efficiently. A method for measuring the thickness of the second fiber layer will be described later.

Since the sanitary nonwoven fabric having the above configuration uses fibers containing polyamide resin among synthetic resins, when the fibers come into contact with the wearer's skin, the heat caused by the wearer's body temperature is transferred from the wearer. It can be transferred quickly to sanitary nonwovens or to other fabrics that are not in contact with the wearer. As a result, when the wearer's skin comes into contact with the sanitary nonwoven fabric, the wearer can perceive a cool sensation, and can be provided with a comfortable feeling of use due to the cool sensation. In addition, the flexibility and hygroscopicity of the polyamide resin are exhibited satisfactorily, and this point also contributes to the improvement of the feeling of use.
In addition, since the sanitary nonwoven fabric has fusion points between fibers, heat can be easily transferred to other fibers, and a good texture as a fiber sheet can be developed. , can improve usability and comfort.
In addition, since the sanitary nonwoven fabric is formed in the form of a fiber sheet, the contact area between the wearer's skin and the sanitary nonwoven fabric is increased, and the wearer can perceive a cool sensation. , flexibility resulting from the configuration of the nonwoven fabric can be expressed.

The total basis weight of the sanitary nonwoven fabric of the present invention is preferably 10 g/m ² or more, more preferably 15 g/m ² or more, still more preferably 18 g/m ² or more.
The total basis weight of the sanitary nonwoven fabric of the present invention is preferably 200 g/m ² or less, more preferably 150 g/m ² or less, and even more preferably 120 g/m ² or less.
With the above-described structure, it is possible to reduce the difference in perception of coldness caused by the uneven basis weight of the sanitary nonwoven fabric, and to effectively fuse and consolidate the fibers. , a sanitary nonwoven fabric having a predetermined volumetric filling rate can be produced with high productivity.
When the sanitary nonwoven fabric of the present invention is incorporated as a constituent member of a sanitary product, the fiber sheet having the highest cool contact q _max value, which will be described later, is taken as the sanitary nonwoven fabric, and its basis weight is measured.

The above-described sanitary nonwoven fabric may be used as it is, or may be used as a constituent member of a sanitary product to provide a sanitary product comprising the sanitary nonwoven fabric.
Further, when the sanitary nonwoven fabric of the present invention is incorporated into sanitary products, it is preferable that the nonwoven fabric or the first fiber layer side of the nonwoven fabric forms the surface facing the wearer's skin.
In either case they are typically disposable.

Sanitary products comprising the sanitary nonwoven fabric of the present invention include, for example, absorbent articles such as disposable diapers, sanitary napkins, underarm sweat pads, incontinence pads, panty liners, and sanitary masks such as face masks and eye masks. goods, but sanitary goods are not limited to these. For example, absorbent articles comprising sanitary nonwoven fabrics broadly include articles used to absorb liquid discharged from the human body.

Sanitary nonwoven fabrics can be used as constituent members of absorbent articles and the like.
Absorbent articles typically comprise a topsheet and a backsheet, with an absorbent body disposed between the topsheet and the backsheet, in addition to or without the topsheet or the backsheet. It can be used as it is in a state where the sanitary nonwoven fabric is arranged.

When sanitary non-woven fabric is used as a component of absorbent articles, etc., the sanitary non-woven fabric should not be worn when using sanitary articles such as absorbent articles, or when handling sanitary articles such as absorbent articles such as taking them out of their packaging. It can be placed at a site that comes into direct contact with the skin of a person. In other words, the sanitary nonwoven fabric is preferably arranged on the outer surface of sanitary articles such as absorbent articles.
The outer surface of a sanitary article such as an absorbent article refers to the surface of a sanitary article such as an absorbent article that can be touched by the wearer after the package is opened and the sanitary article such as an absorbent article is taken out. containing, but not the inner surface that progresses in the thickness direction, but the surface side). Thus, the outer surface of the sanitary article is preferably the skin-facing surface or the non-skin-facing surface.

Specifically, when a sanitary nonwoven fabric is used for a disposable diaper as an absorbent article, which is one embodiment of a sanitary product, for example, a surface sheet, a side nonwoven fabric, a waist gather, a gather placed near the groin, and an exterior It can be used as a structural member such as a body. Among these, by using a sanitary nonwoven fabric for at least the exterior body, the sanitary article such as an absorbent article can be touched by the wearer's hand when it is taken out, so that the sanitary article has a good touch and excellent quality. can be easily reminded of by the wearer.

In the case of using sanitary non-woven fabrics for urine leakage pads and sanitary napkins as absorbent articles, which are one embodiment of sanitary products, for example, the configuration of the surface sheet, side non-woven fabric, hip guard, or individual packaging bag. It can be used as a member.
In addition, when sanitary nonwoven fabrics are used for urine leakage pads and sanitary napkins as absorbent articles, which are one embodiment of sanitary products, they can be used as constituent members such as topsheets and gathers placed near the groin, for example. can.

When using sanitary products such as absorbent articles, from the viewpoint of reducing discomfort due to dampness by making a sensation of coldness perceptible, sanitary nonwoven fabrics are used when sanitary products such as absorbent articles are worn in an appropriate position. , the surface of the absorbent article facing the skin of the wearer who wears the sanitary product (hereinafter also referred to as "skin-facing surface").

Absorbent bodies used in absorbent articles comprise an absorbent core. The absorbent core is, for example, a pile of hydrophilic fibers such as cellulose such as pulp, a mixed pile of hydrophilic fibers and a water-absorbing polymer, a pile of water-absorbing polymers, and a water-absorbing space between two sheets. It is composed of an absorbent sheet or the like in which a hydrophilic polymer is retained, and typically contains hydrophilic fibers and a water-absorbing polymer.
The absorbent core may be covered with a corewrap sheet. As a covering mode of the core wrap sheet, for example, at least the skin-facing surface may be covered with a liquid-permeable core wrap sheet, and the entire surface including the skin-facing surface and the non-skin-facing surface is covered with the core wrap sheet. May be covered. As the core wrap sheet, for example, a thin paper made of hydrophilic fibers, a liquid-permeable nonwoven fabric, or the like can be used.

When the sanitary nonwoven fabric is used as a mask, for example, the sanitary nonwoven fabric can be used alone or as a laminate obtained by laminating another sanitary nonwoven fabric on the sanitary nonwoven fabric. In addition, the member containing the sanitary nonwoven fabric may be provided with an ear hook portion so that the member containing the sanitary nonwoven fabric can be configured to keep the mouth, nose or eyes covered.
Even in this form, the sanitary nonwoven fabric is preferably placed on the skin-facing surface, and more preferably placed on the part that comes into direct contact with the wearer's skin.

When the sanitary nonwoven fabric of the present invention is used to make a sanitary product, the sanitary product is a sanitary nonwoven fabric that is an assembly of fibers containing a polyamide resin (hereinafter, this is also referred to as a "first fiber assembly" for convenience of explanation. ), a further member (hereinafter also referred to as a “second member”) may be provided.

Examples of embodiments of sanitary products in which the second member is arranged include, for example, an absorbent sheet containing a water-absorbing polymer and fibers, an absorbent body containing a water-absorbing polymer and fibers, a hydrophilic non-woven fabric, etc. At least one of can be used. These are examples of fiber aggregates different from sanitary nonwoven fabrics. Sanitary articles having these second members preferably include the absorbent articles described above.
In other words, in the present embodiment, the sanitary nonwoven fabric, which is the first fiber assembly, and the absorbent sheet, the absorbent body, and/or the nonwoven fabric, which are the second members separate from the sanitary nonwoven fabric, are used as the constituent materials of the sanitary article. and are arranged. It is also preferable that the first fiber assembly and the second member are arranged adjacent to each other. Each fiber assembly in this embodiment may or may not be joined to each other.
As the absorbent sheet, for example, the absorbent sheet described in JP-A-8-246395 can be used.

In the case where the sanitary article comprises the above-described second member, or the sanitary nonwoven fabric includes the above-described second fiber layer, the second member or the second fiber layer should have a thickness change of a predetermined value or more. is preferred.
Specifically, the amount of compressive deformation of the second member under a load of 9.8 mN/cm ² (1 gf/cm ² ) is preferably 0.3 mm or more, more preferably 0.5 mm or more. Further, the amount of compressive deformation of the second member under the same load is preferably 3 mm or less. As will be described later, the amount of compressive deformation is expressed as the amount of change obtained by subtracting the thickness of the second member under a load of 9.8 mN/cm ² (1 gf/cm ² ) from the thickness of the second member under no load. be done.
It is preferable that the second fiber layer constituting the sanitary nonwoven fabric also has a similar amount of compressive deformation. In addition to this, when the sanitary article includes both the sanitary nonwoven fabric having a multi-layer structure and the second member, it is preferable that both the second member and the second fiber layer satisfy the compressive deformation amounts described above.
With such a configuration, when the first fiber assembly touches the wearer, the first fiber assembly easily deforms following the deformation of the second member, and the wearer feels comfortable. By increasing the contact area, it is possible to make the wearer perceive a cool sensation efficiently.

The second fiber layer having the above-mentioned physical properties is, for example, a fiber made of PET resin or PP resin, or a PET/HDPE core-sheath composite fiber, etc., used as a constituent fiber in the manufacturing method described later, and a fiber subjected to an air-through treatment. It can be obtained by using a web.
When the second member is an absorbent sheet or an absorbent body, it can be obtained, for example, by appropriately adjusting the basis weights of the fibers, fiber sheets, and water-absorbent polymer that constitute the absorbent sheet or absorbent body.

The thickness of the second member or the second fiber layer can be measured, for example, by the following method.
First, the cross section of the object to be measured is observed visually or by SEM, and the fiber diameter, the distance between fibers, the boundary between members, etc. are observed to determine whether it is a sanitary nonwoven fabric having a plurality of fiber layers, or Confirm that the second member other than the sanitary nonwoven fabric and the sanitary nonwoven fabric is present.
If the object to be measured is a sanitary product, after fixing the structure by immersing the sanitary product in liquid nitrogen, etc., carefully remove the sanitary nonwoven fabric and the second member other than the sanitary nonwoven fabric from the sanitary product to be measured. peel off and separate. Then, the separated members are subjected to the measurement of the above-described cool contact feeling q _max , the fiber sheet with the highest q _max value is taken as the sanitary nonwoven fabric, and the member adjacent to the sanitary nonwoven fabric is taken as the second member.
Then, a plate is placed on the separated second member, etc., and a load of 4.9 mN/cm ² (0.5 gf/cm ² ) is applied, and the thickness in that state is measured using a laser displacement meter. This is the thickness of the second member.
When the object to be measured is a sanitary nonwoven fabric with a multi-layer structure, the fiber layer on the surface side with the highest value of q _max , which will be described in detail in the examples described later, is the first fiber layer, and is adjacent to the first fiber layer. The second fiber layer is used as the second fiber layer, and the second fiber layer is subjected to the above-described measurement.

In the sanitary article as a whole, the amount of compression deformation under a load of 9.8 mN/cm ² (1 gf/cm ² ) is preferably 0.3 mm or more, more preferably 0.4 mm or more. In addition, the amount of compressive deformation of the entire sanitary article under the same load is preferably 15 mm or less, more preferably 10 mm or less.
With such a configuration, the nonwoven fabric as a whole can exhibit flexibility and improve the feeling of use, and the contact area of the fiber assembly containing the polyamide resin with the wearer can be increased to provide a cool feeling. can be efficiently perceived by the wearer.

For example, in the case of the air-through method, the amount of compression deformation described above can be obtained by lowering the temperature and speed of the hot air below those normally used, by increasing the number of fibers, or by using a resin with a higher melting point than the temperature of the hot air. This is achieved by using fibers containing such fibers to reduce the fusion between the fibers.
In addition or instead of this, two or more fiber layers are provided, and only one fiber layer is provided with a layer having a higher compression deformation amount than the other fiber layers, or the basis weight of one fiber layer is increased. This can be achieved by increasing the number of fiber layers more than other fiber layers or by blending fibers having a high melting point in one fiber layer.

The amount of compression deformation can be measured using, for example, a KES-FB-3 compression tester manufactured by Kato Tech Co., Ltd. A section of a certain size is used as a sample from the sanitary nonwoven fabric to be measured. The sample is mounted on the test stand of the testing machine and compressed between steel plates with circular flat surfaces of 2 cm ² in area. The compression speed is 0.02 mm/sec, and the maximum compression load is 9.8 mN/cm ² (1 gf/cm ² ). Compression deformation obtained by subtracting the thickness Tm from the thickness T0, where the thickness under no load is T0 (mm) and the thickness under a load of 9.8 mN/cm ² (1 gf/cm ² ) is Tm (mm). The amount (mm) can be calculated as "T0-Tm".

When the second member is an absorbent sheet, the overall basis weight is preferably 40 g/m ² or more, more preferably 60 g/m ² or more, still more preferably 70 g/m ² or more, and more preferably 500 g/m ² Below, more preferably 400 g/m ² or less, still more preferably 300 g/m ² or less.
When the second member is an absorbent body, the overall basis weight is preferably 30 g/m ² or more, more preferably 40 g/m ² or more, still more preferably 50 g/m ² or more, and more preferably 600 g/m ² or less. , more preferably 550 g/m ² or less, still more preferably 500 g/m ² or less.

The sanitary nonwoven fabric preferably has a flexural rigidity value equal to or less than a predetermined value. Specifically, the flexural rigidity value of the sanitary nonwoven fabric is preferably 0.25 gf·cm ² /cm or less, more preferably 0.2 gf·cm ² /cm or less, and even more preferably 0.15 gf·cm ² /cm or less. , more preferably 0.1 gf·cm ² /cm or less. With such a configuration, it becomes easy to bend following an external force, so the contact area with the wearer's skin can be increased, and a cold sensation can be efficiently perceived.

The flexural rigidity value of sanitary nonwoven fabrics is obtained from "Standardization and Analysis of Texture Evaluation (2nd Edition)" (Author: Toshio Kawabata, Publisher: The Textile Machinery Society of Japan, Texture Measurement and Standardization Research Committee, Publication date: July 10, 1980), pp. 27-28, can be measured by the following method.
Specifically, a cut sample with a size of 20 cm in the length direction and 10 cm in the width direction is obtained. The sample is attached to the chucks of a pure bending tester (trade name: KES-FB2) manufactured by Kato Tech Co., Ltd. so that the distance between the chucks is 10 mm. The direction of attachment is such that the longitudinal direction of the sanitary nonwoven fabric is the bending direction. Pure bending with constant velocity curvature is performed in the range of curvature K=−2.5 to +2.5 cm ⁻¹ . The deformation speed is 0.50 cm ⁻¹ /sec. By this operation, the relationship (MK curve) between the bending moment M per unit area of the sample and the curvature K is obtained. From the results, the bending stiffness B (gf·cm ² /cm) per unit length, which is the slope of the MK curve, is calculated. B is the slope between K=0.5 cm ⁻¹ and K=1.5 cm ⁻¹ and the slope between K=−0.5 cm ⁻¹ and K=−1.5 cm ⁻¹ , K are measured from the characteristics of the process of increasing the absolute value of , and are defined as Bf and Bb, respectively. The arithmetic average value (Bf+Bb)/2 is taken as the bending stiffness value of the present invention.

The fiber diameter of the fibers used in the sanitary non-woven fabric is preferably 1 μm or more, more preferably 5 μm or more, and still more preferably 12 μm or more, from the viewpoint that the constituent fibers do not cling to the skin and the tactile sensation and feeling of use of the wearer are kept good. is.
In addition, from the viewpoint of reducing the interstices between fibers in the nonwoven fabric, reducing the air content in the nonwoven fabric, and enhancing the thermal conductivity, the thickness is preferably 40 μm or less, more preferably 30 μm or less, and even more preferably 27 μm or less.
The fiber diameter of the fiber is measured by preparing a measurement sample and observing the SEM in the same manner as in the measurement method for each length of the long axis and short axis in the cross-sectional shape of the fiber, and measuring the fiber diameter of 10 fibers per sample. Then, the arithmetic average value is taken as the fiber diameter of the present invention. When the fiber is non-perfect circular, each length of the long axis and short axis of the fiber is measured by the above method, and the arithmetic mean value of the long axis length and the short axis length of one fiber is the fiber diameter. , and the arithmetic average value of the ten fiber diameters is taken as the fiber diameter of the fiber in the present invention.

The fiber length of the fibers used in the sanitary nonwoven fabric is preferably 30 mm or more, more preferably 38 mm or more, in the case of short fibers, from the viewpoint of keeping the wearer's tactile sensation and usability good. In addition, from the viewpoint of enhancing thermal conductivity, in the case of short fibers, the length is preferably 40 mm or more, more preferably 45 mm or more. In the case of short fibers, the length is preferably 70 mm or less, more preferably 60 mm or less, from the viewpoint of not impairing processability.
The fiber length of the fiber is measured by measuring the distance from the end point to the end point of 10 fibers with a ruler without stretching the fiber as it is when the fiber is in a crimped state. The arithmetic mean value of the lengths is taken as the fiber length of the fibers of the present invention.

As long as the effects of the present invention are exhibited, the sanitary nonwoven fabric of the present invention may further contain a filler for increasing thermal conductivity. Examples of such fillers include at least one of titanium oxide, alumina, boron nitride, magnesium oxide, silica, carbon black, zinc oxide, and carbon nanotubes. The filler may exist within the fibers, between the fibers, or partially exposed on the surface of the fibers and embedded within the fibers.

The above is a description of the sanitary nonwoven fabric of the present invention and sanitary goods comprising the sanitary nonwoven fabric. A preferred method for producing the sanitary nonwoven fabric of the present invention will now be described.
This manufacturing method includes a step (air-through step) of performing an air-through treatment on a fiber web containing a polyamide resin to obtain a fiber assembly.
In addition to this, it is preferable to adopt a step (consolidation step) of performing a consolidation treatment on the obtained fiber assembly.
Further, it is more preferable that the conjugate fiber used in this production method is the core-sheath conjugate fiber described above.

First, a web of fibers containing polyamide resin is formed. The fiber web can be formed, for example, by a carding method using a known carding machine.

Next, the fiber web is subjected to an air-through treatment in which hot air is blown to obtain a fiber assembly containing fibers containing a polyamide resin. This step is a step of forming a fiber web into a nonwoven fabric, and the fiber assembly thus produced is generally called an air-through nonwoven fabric.

In general, when a fiber web containing a polyamide resin is air-through processed, the use of composite fibers such as core-sheath composite fibers is advantageous in terms of increasing the texture and strength of the resulting air-through nonwoven fabric. There is room for improvement in terms of making the wearer perceive a cool sensation due to the improvement.
As a result of intensive studies by the present inventors on these improvements, it was found that an air-through nonwoven fabric having good texture and strength can be efficiently produced by controlling the temperature and wind speed of the hot air in the air-through process.

In the air-through step, it is preferable that the temperature and wind speed of the hot air blown onto the fiber web be within specific ranges. Specifically, the temperature of the hot air blown onto the fiber web maintains the shape of the fibers without causing the fibers to form a film, in relation to the melting point Mp (°C) of the resin that forms the surface of the fibers that form the fiber web. From the viewpoint of improving the texture of the resulting sanitary nonwoven fabric, the melting point Mp+10° C. or less, more preferably melting point Mp+9° C. or less, and even more preferably melting point Mp+8° C. or less can be set.
In addition, from the viewpoint of appropriately fusing the fibers constituting the fibrous web with each other so that the sanitary nonwoven fabric exhibits a strength that can withstand use, the temperature of the hot air blown onto the fibrous web is preferably the melting point Mp-4° C. or higher. More preferably, the melting point Mp is −2° C. or higher, and more preferably the melting point Mp or higher.
When the core-sheath composite fiber is used in the present production method, it is preferable to use a fiber in which the melting point of the resin constituting the core in the core-sheath composite fiber is higher than the melting point of the resin constituting the sheath. is preferable from the viewpoint of further improving the texture of the resulting nonwoven fabric and making it easy to perceive a cool sensation.

The air-through process can be performed, for example, by blowing hot air onto the fiber web on the net conveyor using an air-through furnace. In this case, the temperature of the hot air described above is the temperature at the position of the centroid of the hot air outlet in plan view and directly above the net conveyor. This temperature can be measured, for example, using a thermocouple.

As the fibers constituting the fiber web, for example, the sheath constituting the fiber surface is HDPE (melting point Mp: 130 ° C.), and the core is polyamide resin nylon 6 (melting point: 225 ° C.). Core-sheath composite fiber. is used, the temperature of the hot air can be preferably 126° C. or higher, more preferably 128° C. or higher, and still more preferably 130° C. or higher.
The temperature of the hot air under the above conditions is preferably 140° C. or lower, more preferably 139° C. or lower, and even more preferably 138° C. or lower.

When fibers made of polyamide resin are used as the fibers constituting the fiber web, for example, nylon 6 (melting point Mp: 225°C), the temperature of the hot air is preferably 221°C or higher, more preferably 223°C or higher. More preferably, it can be 225° C. or higher. The temperature of the hot air under the above conditions is preferably 235° C. or lower, more preferably 234° C. or lower, and even more preferably 233° C. or lower.
When nylon 66 (melting point Mp: 265°C) is used as a fiber made of polyamide resin, the temperature of the hot air can be preferably 261°C or higher, more preferably 263°C or higher, and still more preferably 265°C or higher. The temperature of the hot air under the above conditions is preferably 275° C. or lower, more preferably 274° C. or lower, and even more preferably 273° C. or lower.

The melting point Mp of the resin that forms the fiber surface can be measured using a differential scanning calorimeter (DSC7000x, manufactured by Hitachi High-Tech Science Co., Ltd.). First, using a finely cut fiber sample (1 mg), thermal analysis of the sample is performed at a heating rate of 10° C./min to measure the melting peak temperature of each resin. The melting point is defined as the melting peak temperature during the first heating. If the melting point cannot be unambiguously determined by this method, the resin is defined as "a resin without a melting point". If the resin does not have a melting point, the softening point is the melting point Mp.

In the air-through step, the wind speed of the hot air blown onto the fibrous web is preferably 0.6 m/sec or more, from the viewpoint of allowing the hot air to sufficiently pass through the fibrous web in the thickness direction of the fibrous web and facilitating the formation of fusion bonds between the fibers. More preferably, it is 1.0 m/sec or more.
From the same point of view, the velocity of the hot air blown onto the fibrous web is preferably 2.0 m/sec or less, more preferably 1.4 m/sec or less.
By performing the air-through process under the temperature and wind speed conditions described above, the resin existing on the surface of the fibers constituting the fiber web is melted or softened, and the fusion points where the fibers are fused together can be randomly formed. Therefore, the manufactured sanitary nonwoven fabric exhibits the softness and good texture attributed to the air-through nonwoven fabric, and exhibits strength to withstand use.

The conveying speed of the fiber web in the air-through step is preferably 3 m/min or more, more preferably 10 m/min or more, and preferably 200 m/min or less, more preferably 160 m/min or less, within the temperature and wind speed ranges described above. is.

Since the fiber assembly obtained through the above steps is made into a nonwoven fabric, it may be used as it is as the sanitary nonwoven fabric of the present invention. This sanitary nonwoven fabric is an air-through nonwoven fabric.

From the viewpoint of easily obtaining a sanitary nonwoven fabric having a predetermined volumetric filling rate, it is preferable to further perform a consolidation treatment on the fiber assembly obtained through the above steps (consolidation step). For the consolidation treatment in this step, a method capable of compressing the fiber assembly by pressurizing it in its thickness direction can be adopted.

As the consolidation treatment, for example, a method of placing a fiber aggregate between two metal flat plates and pressing (hereinafter, this method is also referred to as a “press method” or “press treatment”), or a method in which both peripheral surfaces are smooth A method in which a fiber assembly is introduced between a pair of rolls and pressurized (hereinafter, this method is also referred to as "calendering method" or "calendering").
The consolidation process may be performed once or, if desired, multiple times in the same or different manners. The temperature in the consolidation treatment may be room temperature, may be in a heated state, or may be a combination thereof.
From the viewpoint of increasing the production efficiency, it is preferable to adopt the calendering method, and from the viewpoint of efficiently performing the consolidation in the heated state without temperature unevenness, the calendering method is used using a pair of rolls whose peripheral surfaces are made of metal or the like. It is more preferable to provide

As for the condition of the consolidation treatment, it is preferable to pressurize in a heated state. Specifically, the pressurization conditions in the consolidation process are expressed in terms of surface pressure when using a press method, from the viewpoint of sufficiently consolidating the fiber assembly and easily obtaining a sanitary nonwoven fabric with a high volume filling rate. , preferably 5 MPa or more, more preferably 7 MPa or more.
In addition, from the viewpoint of improving the texture of the sanitary nonwoven fabric obtained while maintaining the fiber shape in which the boundaries between the constituent fibers are clear without making the fiber aggregate into a film, the heat treatment in the consolidation treatment is performed. When the press method is used, the pressure condition is preferably 72 MPa or less, more preferably 32 MPa or less, in terms of surface pressure.

In addition, the pressurization conditions when the calendering method is employed are expressed in linear pressure, preferably 78.0, from the viewpoint of sufficiently consolidating the fiber assembly and easily obtaining a sanitary nonwoven fabric with a high volume filling factor. It is 4 N/cm (8 kgf/cm) or more, more preferably 127.4 N/cm (13 kgf/cm) or more.
In addition, the calendering method was adopted from the viewpoint of obtaining a sanitary nonwoven fabric with a good texture while maintaining a fiber shape with clear boundaries between constituent fibers without making the fiber assembly into a film. The pressurization conditions are preferably 686 N/cm (70 kgf/cm) or less, more preferably 490 N/cm (50 kgf/cm) or less, still more preferably 294 N/cm (30 kgf/cm) or less, in terms of linear pressure. is.

In addition, the heating temperature in the consolidation treatment is the following from the viewpoint of sufficiently consolidating the fiber aggregate and easily obtaining a sanitary nonwoven fabric with a high volume filling factor, regardless of whether it is a pressing method or a calendering method. The melting point Mp is preferably −80° C. or higher, more preferably melting point Mp −70° C. or higher, and still more preferably melting point Mp −60° C. or higher.
From the viewpoint of maintaining a fiber shape with clear boundaries between constituent fibers without making the fiber assembly into a film and improving the texture of the obtained sanitary nonwoven fabric, either a pressing method or a calendering method is used. Even in the case of , it is preferably in the range of the melting point Mp or lower, more preferably in the range of the melting point Mp-20° C. or lower.
When heating in the consolidation treatment, the flat metal plate may be heated to the temperature range described above in the case of the press method, and the circumferential surface of the roll may be heated to the temperature range described above in the case of the calender method.

The pressurization time in the consolidation process can be appropriately set as long as the fiber shape of the fibers constituting the fiber assembly is maintained and consolidation is possible.
For example, when a pressing method is used, the pressurization time under the pressure and temperature conditions described above can be preferably 5 seconds or more, more preferably 10 seconds or more, per one consolidation treatment.
Further, when the pressing method is used, the pressurization time under the above pressure and temperature conditions can be preferably 25 seconds or less, more preferably 20 seconds or less, per one consolidation treatment.

For example, when a calendering method is used, the pressurization time under the pressure and temperature conditions described above is preferably 0.01 seconds or longer, more preferably 0.04 seconds or longer, per one consolidation treatment. .
In addition, when the calendering method is used, the pressurization time under the pressure and temperature conditions described above is preferably 0.10 seconds or less, more preferably 0.08 seconds or less, per one consolidation treatment. .

By performing the consolidation treatment under the above conditions, the fiber aggregate can be compressed in the thickness direction to obtain a sanitary nonwoven fabric having a predetermined volume filling ratio and thickness.
In particular, within the ranges of pressure and heating temperature described above, the morphological stability and dimensional stability can be enhanced by heat treatment while the constituent resin of the fiber is unlikely to melt, so the shape of the fiber can be maintained even after production. It is possible to obtain a sanitary nonwoven fabric that maintains a predetermined volume filling rate while maintaining a predetermined volumetric filling rate.
Moreover, when fibers having a perfect circular cross-sectional shape are used, the cross-sectional shape of the fiber can be flattened by the consolidation treatment, so there is also the advantage that the volume filling factor can be increased.
The sanitary nonwoven fabric obtained by the above method is an air-through nonwoven fabric even after undergoing the consolidation treatment.

In the case of producing the desired sanitary non-woven fabric having a multilayer structure, for example, a second fiber web containing a thermoplastic resin formed by a carding method is laminated on a fiber web containing a polyamide resin to obtain fibers. A laminate of webs. By subjecting the laminate to an air-through treatment, an air-through nonwoven fabric, which is a fiber aggregate having a multi-layer structure, can be obtained. In this nonwoven fabric, the boundaries of each fiber layer are unclear. At this time, it is preferable that the temperature of the hot air to be blown is determined by taking the melting point of the resin having the lowest melting point as the melting point Mp described above.

In the above-described case, it is preferable that the step of blowing hot air in the air-through treatment arranges the laminate of the fiber webs so that the hot air is blown against the fiber web other than the fiber web containing the polyamide resin. By adopting such a method, the fibers in the fiber web containing the polyamide resin are thermally fused together by the pressure of the hot air to form the first fiber assembly having a high volume filling factor, and the second fiber web is formed. It is possible to obtain a nonwoven fabric for sanitary use having a structure in which bulkiness is maintained on the side and which is excellent in compressive deformation property.
As such a method, for example, the side of the laminate on which the fiber web containing the polyamide resin is arranged may be arranged on the lower surface side such as the net side of the air-through device to perform the air-through treatment.

Another form of manufacturing a sanitary nonwoven fabric having a multilayer structure is to obtain fiber sheets by subjecting a fiber web containing a polyamide resin and a second fiber web containing a thermoplastic resin to an air-through treatment, respectively. It can be obtained by joining fiber sheets with an adhesive or by various embossing methods such as fusion bonding, adhesion, or pressure bonding.

The sanitary nonwoven fabric of the present invention can also be produced by a method based on the spunbond method instead of the production method described above. That is, a process (spunbonding process) of obtaining a fiber assembly by performing a spunbonding process on the polyamide resin may be provided. The sanitary nonwovens thus produced are spunbonded nonwovens.

Specifically, raw material resin of fibers is extruded in a molten state through a spinneret having a large number of pores, and the extruded resin is drawn with a roll or the like to form long fibers, and these long fibers are accumulated on a net conveyor. to obtain a web of fibers containing a polyamide resin. After that, the fiber web is introduced between embossing rolls having a plurality of protrusions on the peripheral surface, and densification (thermocompression bonding) is performed by heating and pressurizing to obtain the sanitary nonwoven fabric of the present invention. In other words, in this method, the formation of fused points between constituent fibers, the formation of a non-woven fabric from the fiber web, and the consolidation treatment are performed at the same time.

The temperature of the embossing roll is preferably in the range of melting point Mp-40°C or higher, more preferably melting point Mp-35°C or higher, and still more preferably melting point Mp-30°C or higher.
From the viewpoint of sufficiently fusing the embossed portions, the pressure conditions of the embossing rolls are preferably in the range of 0.3 MPa or higher, more preferably 0.5 MPa or higher, and even more preferably 1.0 MPa or higher.
Moreover, from the viewpoint of preventing perforation due to excessive pressurization, the pressurization conditions are preferably 40 MPa or less, more preferably 35 MPa or less, and still more preferably 30 MPa or less.

In the case of manufacturing the intended sanitary nonwoven fabric having a multilayer structure, for example, a second fiber web containing a thermoplastic resin formed by a carding method is laminated on a fiber web containing a polyamide resin, A laminate of fiber webs. Then, consolidation (thermocompression bonding) may be performed on the laminate by heating and pressurizing under the conditions described above.

The sanitary nonwoven fabric of the present invention can be obtained through the above steps. This sanitary nonwoven fabric is preferably incorporated as a constituent member of sanitary articles such as absorbent articles in subsequent steps.
When sanitary nonwoven fabric is used as a constituent material for sanitary products such as absorbent articles, the sanitary nonwoven fabric produced by the above method is used as one of the constituent materials in any of the steps of producing the sanitary product, One or more of the steps of cutting the sanitary nonwoven fabric and performing various operations such as laminating or joining the sanitary nonwoven fabric and other constituent materials constituting the sanitary product (e.g., absorbent bodies, sheets, etc.) It is possible to manufacture sanitary products such as absorbent articles of interest.

Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to the above embodiments.

Regarding the embodiment of the present invention described above, the following sanitary nonwoven fabric and method for producing the same are further disclosed.
<1>
A fiber assembly containing fibers containing a polyamide resin,
The fiber aggregate has a fusion point where the constituent fibers are fused together,
A nonwoven fabric for sanitary use, wherein the fiber assembly containing fibers containing a polyamide resin has a volume filling rate of 3.5% or more.

<2>
The volume filling rate of the fiber aggregate containing fibers containing the polyamide resin is preferably 7.0% or more, more preferably 10.0% or more, still more preferably 12.0% or more, and still more preferably 14.0%. % or more,
The volume filling rate is preferably 60.0% or less, more preferably 50.0% or less, still more preferably 45.0% or less, even more preferably 35.0% or less, and even more preferably 30.0% or less. and
The volume filling rate is preferably 7.0% or more and 60.0% or less, more preferably 7.0% or more and 50.0% or less, still more preferably 10.0% or more and 45.0% or less, still more preferably The sanitary nonwoven fabric according to <1> above, wherein the content is 12.0% or more and 35.0% or less, and more preferably 14.0% or more and 30.0% or less.

<3>
The sanitary nonwoven fabric according to <1> or <2>, wherein the fibers are composite fibers containing a polyamide resin.
<4>
The sanitary nonwoven fabric according to <3> above, wherein the composite fiber is a composite fiber containing a polyamide resin inside the fiber.
<5>
The sanitary nonwoven fabric according to <3> or <4> above, wherein the composite fiber is a composite fiber further containing a polyethylene resin on the entire outer surface of the fiber.

<6>
The sanitary nonwoven fabric according to any one of <1> to <5>, wherein the fiber is a core-sheath composite fiber having a core made of polyamide resin and a sheath made of high-density polyethylene resin.
<7>
The content of the polyamide resin relative to the total mass of the fibers contained in the sanitary nonwoven fabric is preferably 25% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, and preferably 100% by mass or less. , More preferably 90% by mass or less, still more preferably 80% by mass or less, the sanitary nonwoven fabric according to any one of <1> to <6>.
<8>
The sanitary nonwoven fabric according to any one of <1> to <7>, wherein the polyamide resin is one or more of nylon 6, nylon 66, and aromatic nylon.
<9>
the fibers further comprise a polyethylene resin;
The content of the polyethylene resin relative to the total mass of the fibers contained in the sanitary nonwoven fabric is preferably 30% by mass or more, more preferably 40% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less. The sanitary nonwoven fabric according to any one of <1> to <8> above.

<10>
The sanitary nonwoven fabric further comprises a polyethylene resin,
The mass ratio of the polyamide resin to the polyethylene resin contained in the sanitary nonwoven fabric (polyamide resin/polyethylene resin) is preferably 0.1 or more, more preferably 0.2 or more, and still more preferably 0.3 or more. is 2.0 or less, more preferably 1.5 or less, still more preferably 1.3 or less, the sanitary nonwoven fabric according to any one of <1> to <9>.

<11>
The sanitary nonwoven fabric further comprises a polyethylene resin,
The polyethylene resin includes low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), high-density polyethylene resin (HDPE), linear low-density polyethylene resin (LLDPE), and ethylene-propylene copolymer. one or two or more,
The sanitary nonwoven fabric according to any one of <1> to <10>, which is preferably a high density polyethylene resin (HDPE).
<12>
The sanitary nonwoven fabric according to any one of <1> to <11>, having a mean deviation (MMD) of coefficient of friction of 0.010 or less.
<13>
Any one of <1> to <12> above, wherein the mean deviation (MMD) of the coefficient of friction is preferably 0.009 or less, more preferably 0.008 or less, and preferably 0.004 or more. sanitary nonwovens.

<14>
The overall thickness of the sanitary nonwoven fabric under a load of 4.9 mN/cm ² (0.5 gf/cm ² ) is preferably 0.05 mm or more, more preferably 0.08 mm or more, and preferably 8 mm or less. The sanitary nonwoven fabric according to any one of <1> to <13>, which is preferably 7.5 mm or less, more preferably 7 mm or less.
<15>
The total basis weight of the sanitary nonwoven fabric is preferably 10 g/m ² or more, more preferably 15 g/m ² or more, still more preferably 18 g/m ² or more, and preferably 200 g/m ² or less, more preferably The sanitary nonwoven fabric according to any one of <1> to <14>, which has a weight of 150 g/m ² or less, more preferably 120 g/m ² or less.
<16>
A cool contact q _max of the fiber assembly of the sanitary nonwoven fabric is preferably 0.06 W/m ² or more, more preferably 0.08 W/m ² or more, and still more preferably 0.10 W/m ² or more. , preferably 0.80 W/m ² or less, more preferably 0.60 W/m ² or less, still more preferably 0.50 W/m ² or less, according to any one of the above <1> to <15> Sanitary non-woven fabric.
<17>
The heat conductivity of the fiber assembly of the sanitary nonwoven fabric is preferably 0.08 W/mK or more, more preferably 0.10 W/mK or more, and still more preferably 0.13 W/mK or more, above <1> to The sanitary nonwoven fabric according to any one of <16>.

<18>
The flexural rigidity value of the sanitary nonwoven fabric is preferably 0.25 gf·cm ² /cm or less, more preferably 0.2 gf·cm ² /cm or less, even more preferably 0.15 gf·cm ² /cm or less, and still more preferably. is 0.1 gf·cm ² /cm or less, the sanitary nonwoven fabric according to any one of <1> to <17>.
<19>
The fiber diameter of the fiber is preferably 1 μm or more, more preferably 5 μm or more, still more preferably 12 μm or more, preferably 40 μm or less, more preferably 30 μm or less, still more preferably 27 μm or less. The sanitary nonwoven fabric according to any one of <18>.
<20>
The sanitary product according to any one of <1> to <19>, wherein the fiber length of the fiber is preferably 30 mm or more, more preferably 38 mm or more, and preferably 70 mm or less, more preferably 60 mm or less. non-woven fabric.
<21>
The sanitary nonwoven fabric according to any one of <1> to <20>, further comprising a filler.
<22>
The sanitary nonwoven fabric according to <21>, wherein the filler is one or more of titanium oxide, alumina, boron nitride, magnesium oxide, silica, carbon black, zinc oxide, and carbon nanotubes.

<23>
Having a first fiber layer made of the fiber assembly and a second fiber layer made of the second fiber assembly arranged adjacent to the first fiber layer,
The sanitary nonwoven fabric according to any one of <1> to <22>, wherein the second fiber assembly has a compressive deformation amount of 0.3 mm or more under a load of 9.8 mN/cm ² .
<24>
The sanitary nonwoven fabric according to <23>, wherein the first fiber layer is arranged on the outer surface.
<25>
The basis weight of the first fiber layer is preferably 10 g/m ² or more, more preferably 15 g/m ² or more, still more preferably 18 g/m ² or more, and preferably 200 g/m ² or less, more preferably The sanitary nonwoven fabric according to <23> or <24> above, which is 150 g/m ² or less, more preferably 100 g/m ² or less.
<26>
The basis weight of the second fiber layer is preferably 10 g/m ² or more, more preferably 15 g/m ² or more, still more preferably 20 g/m ² or more, and preferably 140 g/m ² or less, more preferably 90 g/m 2 or more. The sanitary nonwoven fabric according to any one of <23> to <25>, which has a m ² or less, more preferably 70 g/m ² or less.
<27>
The amount of compressive deformation of the second fiber layer under a load of 9.8 mN/cm ² (1 gf/cm ² ) is preferably 0.3 mm or more, more preferably 0.5 mm or more, and preferably 3 mm or less. The sanitary nonwoven fabric according to any one of <23> to <26>.

<28>
A sanitary nonwoven fabric according to any one of <1> to <27> and a second member arranged adjacent to the nonwoven fabric,
The sanitary product, wherein the second member has a compressive deformation amount of 0.3 mm or more under a load of 9.8 mN/cm ² .
<29>
The sanitary product according to <28> above, wherein the compressive deformation amount of the second member under a load of 9.8 mN/cm ² (1 gf/cm ² ) is preferably 0.5 mm or more and preferably 3 mm or less. .
<30>
The sanitary article according to <28> or <29> above, wherein the entire sanitary article has a compressive deformation amount of 0.3 mm or more under a load of 9.8 mN/cm ² .
<31>
The amount of compressive deformation of the entire sanitary article under a load of 9.8 mN/cm ² (1 gf/cm ² ) is preferably 0.4 mm or more, preferably 15 mm or less, more preferably 10 mm or less. 28> to <30>, the sanitary product according to any one of the above items.

<32>
The sanitary product according to any one of <28> to <31>, wherein the second member is an absorbent body or an absorbent sheet.
<33>
the second member is an absorbent sheet,
The total basis weight of the absorbent sheet is preferably 40 g/m ² or more, more preferably 60 g/m ² or more, still more preferably 70 g/m ² or more, and preferably 500 g/m ² or less, more preferably The sanitary goods according to any one of <28> to <32> above, which is 400 g/m ² or less, more preferably 300 g/m ² or less.

<34>
the second member is an absorber,
The basis weight of the entire absorbent body is preferably 30 g/m ² or more, more preferably 40 g/m ² or more, still more preferably 50 g/m ² or more, preferably 600 g/m ² or less, more preferably 550 g. /m ² or less, more preferably 500 g/m ² or less, the sanitary goods according to any one of the above <28> to <32>.
<35>
An absorbent article comprising the sanitary nonwoven fabric according to any one of <1> to <27>.
<36>
The absorbent article according to <35>, wherein the sanitary nonwoven fabric is disposed on the outer surface of the absorbent article.

<37>
The method for producing a sanitary nonwoven fabric according to any one of <1> to <27>,
A method for producing a sanitary nonwoven fabric, comprising a step of subjecting a fiber web containing a polyamide resin to an air-through treatment or a spunbond treatment.
<38>
A step of air-through treating a fiber web containing a polyamide resin,
In the above step, the temperature of the hot air blown onto the fiber web is preferably melting point Mp+10° C. or less, more preferably melting point Mp+9° C. or less, still more preferably melting point Mp+8° C. or less, where melting point Mp is the melting point of the constituent resin of the fiber. , preferably melting point Mp-4°C or higher, more preferably melting point Mp-2°C or higher, and still more preferably melting point Mp or higher.
<39>
A step of air-through treating a fiber web containing a polyamide resin,
In the above step, the velocity of the hot air blown onto the fibrous web is preferably 0.6 m/sec or more, more preferably 1.0 m/sec or more, and preferably 2.0 m/sec or less, more preferably 1.4 m/sec. The manufacturing method according to <37> or <38>, comprising:
<40>
A step of air-through treating a fiber web containing a polyamide resin,
The conveying speed of the fiber web in the step is preferably 3 m/min or more, more preferably 10 m/min or more, and preferably 200 m/min or less, more preferably 160 m/min or less. The production method according to any one of <39>.

<41>
further comprising a step of subjecting the fiber assembly obtained by the air-through treatment or the spunbond treatment to a consolidation treatment,
The manufacturing method according to any one of <37> to <40>, wherein the consolidation treatment is performed while heating at a temperature below the melting point of the constituent resin of the fiber.
<42>
As the consolidation treatment, a press treatment is performed in which the fiber assembly is placed between two metal flat plates and pressed, or a calendering treatment is performed in which the fiber assembly is introduced between a pair of rolls and pressed. The manufacturing method according to <41>.
<43>
As the consolidation treatment, the press treatment is performed,
The production method according to <41> or <42> above, wherein the pressurizing condition in the press treatment is preferably 5 MPa or more, more preferably 7 MPa or more, and preferably 72 MPa or less, more preferably 32 MPa or less.

<44>
As the consolidation treatment, the calendar treatment is performed,
The pressurization conditions in the calendering are preferably 78.4 N/cm (8 kgf/cm) or more, more preferably 127.4 N/cm (13 kgf/cm) or more, and preferably 686 N/cm (70 kgf/cm). The manufacturing method according to <41> or <42> above, more preferably 490 N/cm (50 kgf/cm) or less, still more preferably 294 N/cm (30 kgf/cm) or less.
<45>
The heating temperature in the consolidation treatment is preferably melting point Mp-80° C. or higher, more preferably melting point Mp-70° C. or higher, and still more preferably melting point Mp-60, where Mp is the melting point of the constituent resin of the fiber. ° C. or higher, preferably the melting point Mp or lower, and more preferably the melting point Mp -20°C or lower.

The present invention will be described in more detail below with reference to examples. However, the scope of the invention is not limited to such examples. The column indicated by "-" in the table means non-containing or non-measurement.

[Examples 1 to 3]
A core-sheath composite fiber having nylon 6 as a polyamide resin as a core and HDPE as a sheath was used. The mass ratio of resin, fiber diameter and fiber length are shown in Table 1 below.
First, a web of the composite fiber adjusted to have a basis weight shown in Table 1 below was subjected to an air-through treatment to obtain a fiber assembly in the form of a non-woven fabric. The air-through treatment conditions were as shown in Table 1 below. Next, the fiber aggregate was subjected to a compaction treatment using a pair of flat-surfaced metal plates under the heating and pressurizing conditions shown in Table 1 below to obtain the intended sanitary nonwoven fabric. All of these nonwoven fabrics had a single layer structure.

[Example 4]
The desired nonwoven fabric for sanitary use having a single layer structure was obtained in the same manner as in Example 1, except that the wind speed during the air-through treatment was 1.2 m/sec and the consolidation treatment was performed by a calendering method. A pair of flat rolls with a smooth surface were used with a pressurization condition of 483 N/cm (49.3 kgf/cm) by the calender method.

[Example 5]
In the same manner as in Example 1, except that a core-sheath composite fiber having a core of nylon 6 as a polyamide resin and a sheath of HDPE was used, and the mass ratio of the resin was changed as shown in Table 1 below. A sanitary nonwoven fabric was obtained.

[Example 6]
A web of fibers consisting only of nylon 6 as a polyamide resin was formed by a spunbond method, and the web was subjected to fusion bonding and compaction treatment with an embossing roll to obtain a sanitary nonwoven fabric composed of a spunbonded nonwoven fabric. . The conditions for the spunbond method were as shown in Table 1 below. This nonwoven fabric had a single layer structure.
The length of the fiber obtained by the spunbond method was substantially infinite, and the fiber length was not measured in this example.

[Example 7]
A web of fibers consisting only of nylon 66 as a polyamide resin is formed by a spunbond method, and the web is subjected to fusion bonding and consolidation treatment with an embossing roll under the same conditions as in Example 6 to form a spunbond nonwoven fabric. A sanitary nonwoven fabric consisting of

[Example 8]
In this example, a sanitary nonwoven fabric having a multi-layer structure was produced.
Specifically, a fiber web made of a core-sheath composite fiber having nylon 6 as a polyamide resin as a core and HDPE as a sheath was subjected to an air-through treatment under the same conditions as in Example 1, and then subjected to the same treatment as in Example 1. A single-layer nonwoven fabric (basis weight: 90 g/m ² ) was obtained by performing consolidation treatment under the conditions.
Separately, a second fiber web made of a core-sheath composite fiber having a core of PET and a sheath of PE was prepared, and subjected to air-through treatment and consolidation treatment under the same conditions as in Example 1 to obtain a single layer. A nonwoven fabric (basis weight: 20 g/m ² ) was obtained.
Finally, the respective nonwoven fabrics were laminated and joined via a hot-melt adhesive to obtain the intended multi-layer structure sanitary nonwoven fabric (basis weight: 110 g/m ² ).

[Example 9]
A core-sheath composite fiber having a core made of nylon 6 as a polyamide resin and a sheath made of HDPE and a core-sheath composite fiber having a PET core and a PE sheath were mixed at a mass ratio of 1:1. The air-through treatment and consolidation treatment were performed under the same conditions as in Example 1 to obtain the desired nonwoven fabric. This nonwoven fabric had a single-layer structure without the second fiber assembly.

[Comparative Example 1]
A desired sanitary nonwoven fabric was obtained in the same manner as in Example 1, except that a core-sheath composite fiber having a core of PET and a sheath of HDPE was used without using a polyamide resin.

[Comparative Example 2]
The intended sanitary nonwoven fabric was obtained in the same manner as in Example 1, except that a core-sheath composite fiber having a core of PP and a sheath of HDPE was used without using a polyamide resin.

[Measurement of thickness of sanitary nonwoven fabric]
The thickness of the sanitary nonwoven fabrics of Examples and Comparative Examples was measured. The thickness is measured at five points or more using a laser displacement meter while a load of 4.9 mN/cm ² (0.5 gf/cm ² ) is applied to the sanitary nonwoven fabric to be measured. Let the average value be the thickness (mm). Table 1 shows the results.

[Measurement of volume filling factor]
The volume filling ratio (%) of the sanitary nonwoven fabrics of Examples and Comparative Examples was calculated by the method described above. Table 1 shows the results.

[Measurement of compression deformation amount under 9.8 mN/cm ² load]
The amount of compressive deformation (mm) under a load of 9.8 mN/cm ² was calculated by the method described above for the sanitary nonwoven fabrics of Examples and Comparative Examples. Table 1 shows the results.

[Measurement of MMD]
The MMD of the sanitary nonwoven fabrics of Examples and Comparative Examples was calculated by the method described above. Table 1 shows the results.

[Thermal conductivity of nonwoven fabric]
The thermal conductivity and cool contact sensation of the sanitary nonwoven fabrics of Examples and Comparative Examples were measured by the following methods.
(1. Sample creation)
The sanitary non-woven fabric to be measured is cut into small pieces, and a laminate obtained by laminating multiple sheets of about 10 g is held between two stainless steel plates in the center of the stainless steel plate and heated for 1 minute without pressure. Then, a fused product was obtained. The heating temperature was set to the melting point Mp+20° C. measured by the above-mentioned differential scanning calorimeter, and in the case of a nonwoven fabric containing a plurality of resin materials, the heating was based on the melting point of the resin having the highest melting point. Specifically, it was heated at 245°C.
Then, while maintaining the above-described heating temperature, the obtained fused material is subjected to a gauge pressure of 200 kgf (total mass including the top plate: 21848 kg; when calculating the pressure as a surface pressure, the area of the fused material is the melting of the resin. Since the surface pressure changes with the After holding it for 1 minute, it was cooled with water to 20° C. while maintaining the pressurized state to obtain a circular resin plate with a diameter of about 15 to 20 cm (the diameter of the circular resin plate obtained varies depending on the melt viscosity of the resin). sell).
Subsequently, the obtained circular resin plate was cut radially through the center, and further cut to 5 cm or less if the maximum span length was 5 cm or more. Then, so that the effect of the orientation of the resin is eliminated, the extending direction of the virtual line segment at the maximum span length is random. Two shims were placed in parallel at a distance of 10 cm from the center of the stainless plate, and the stainless plate was placed thereon. After that, heating under no pressure and heating and cooling under pressure were performed in the same manner as described above. If air bubbles were to enter, the same operation was repeated. The purpose of heating and melting twice is to melt the sample once to eliminate effects such as crystallization of the resin, which changes during the fiber spinning process, and to make the heat history constant. This gave a film.

(2. Measurement of thermal conductivity)
Thermal conductivity was measured by the following method using a measuring device (KES-F7 Thermolab II manufactured by Kato Tech Co., Ltd.).
First, the produced film was cut into a size of 10 cm long×10 cm wide, and left for 24 hours in an environment of room temperature of 23° C. and relative humidity of 50%. Then, the thermal conductivity of the measurement object was measured according to the above-mentioned measuring device and the measurement manual of the device. Specifically, the temperature of the heat source for measurement (BT-BOX, an aluminum plate with a length of 5 cm × width of 5 cm and a thickness of 1 mm and a heater etc. are integrated) is set to 33 ° C. In order to prevent the film from warping and reducing the contact area, the heat source body was brought into contact with the film so that a load of 1 kg per 0.25 m ² was applied to the film. . The measurement was started when the heat flow from the heat source to the object to be measured became constant on the display panel of the measuring instrument, and the average heat flow was measured for 60 seconds from that time. It was calculated based on the following formula (III) from the measurement conditions and the measured heat flow rate. The thickness D of the film was the arithmetic mean value of the thicknesses measured at three or more points under no load with a laser displacement meter. The above measurement was performed three times for each object to be measured, and the maximum value of the measured values was taken as the thermal conductivity (W/mK) of the sample. Table 1 shows the results.

k=100×(W×D)/(A×ΔT) (III)
(k: thermal conductivity [W/mK], W: heat flow [W/m ² ], D: film thickness [cm], A: aluminum plate area (25 cm ² ), ΔT: heat source and film Temperature difference (10°C))

[Measurement of cool contact sensation]
The cool contact sensation was measured by the following method using a measuring device (KES-F7 Thermolab II manufactured by Kato Tech Co., Ltd.).
First, a sanitary nonwoven fabric to be measured was cut into a size of 23 cm in length×14 cm in width, and left for 24 hours in an environment of room temperature of 23° C. and relative humidity of 50%. Next, in accordance with the above-mentioned measuring device and the measurement manual of the device, the sanitary non-woven fabric to be measured is subjected to a constant temperature device using gas or liquid as a heat medium in order to define the temperature difference from the heat source. It was brought to 23°C.
Subsequently, the cool contact sensation q _max of the measurement object was measured according to the above-described measurement device and the measurement manual of the device. Specifically, a measuring terminal made of pure copper (T-Box) with an area of 9.0 cm ² and a mass of 9.8 g was used as a hot plate to be brought into contact with the object to be measured. 10°C higher than the surface temperature), the contact pressure of the copper plate to the measurement object is 98 mN/cm ² (10 gf/cm ² ), the copper plate is brought into contact with the test piece, and the heat flow value at the moment of contact was taken as zero, and the maximum value of the heat flow was measured. This measurement was performed 5 times for the surface to be measured, and the arithmetic average value of the plurality of measured values was taken as the cool contact sensation q _max (W/m ² ) of the measurement object.
The larger the value of the contact coolness q _max , the larger the amount of heat transfer, the faster the heat transfer, and the easier it is for the wearer to perceive a cold sensation. The results are shown in Table 1 below.

[Evaluation of texture]
The texture of the nonwoven fabrics of Examples and Comparative Examples was evaluated by the following method. Softness, smoothness, and touch were used as the items of the evaluation test for texture. First, 20 expert panelists were allowed to touch the surface of the nonwoven fabric, each item was scored according to the following evaluation criteria, and the average score for each item was calculated. Then, the overall average score was further calculated from the average score of each item, and the average score was used as the evaluation of the texture. Table 1 shows the results.
5 points: Good.
4 points: Slightly good.
3 points: Normal.
2 points: Slightly bad.
1 point: Bad.

[Evaluation of cold feeling]
The cooling sensation of the nonwoven fabrics of Examples and Comparative Examples was evaluated by the following method. First, 20 expert panelists were asked to touch the surface of the nonwoven fabric and score the cold sensation when touching the nonwoven fabric according to the following criteria, and the arithmetic average value was used as the evaluation of the cold sensation. . Table 1 shows the results.
5 points: Very excellent cold feeling. (The cooling sensation is felt as strong as a contact cooling sensation cloth with a q-max of 0.20 or more.)
4 points: Cool feeling is good.
3 points: A cold sensation can be perceived.
2 points: A feeling of coolness is hardly felt.
1 point: no cold sensation is felt. (Like an air-through nonwoven fabric with a q-max of 0.06 or less, it does not feel cold.)

As shown in Table 1, the sanitary nonwoven fabrics of each example had a better texture, higher thermal conductivity and higher volume filling factor than the comparative example, and also had a cool contact q _max . It can be seen that the cooling sensation is higher and the sensation of cooling is more perceptible.
Therefore, the sanitary nonwoven fabric of the present invention has a good feel, and when it touches the skin, it gives a cool sensation and provides a comfortable feeling of use.

According to the present invention, a sanitary non-woven fabric is provided that has a good texture and allows the user to perceive a cool sensation when touching the skin.

Claims

A fiber assembly containing fibers containing a polyamide resin,
The fiber aggregate has a fusion point where the constituent fibers are fused together,
A nonwoven fabric for sanitary use, wherein the fiber assembly containing fibers containing a polyamide resin has a volume filling rate of 3.5% or more.
The sanitary nonwoven fabric according to claim 1, wherein the fiber assembly containing fibers containing the polyamide resin has a volume filling rate of 12.0% or more.
The sanitary nonwoven fabric according to claim 1 or 2, wherein the fibers are composite fibers containing polyamide resin.
The sanitary nonwoven fabric according to any one of claims 1 to 3, wherein the polyamide resin is one or more of nylon 6, nylon 66, and aromatic nylon.
The sanitary nonwoven fabric further comprises a polyethylene resin,
The sanitary product according to any one of claims 1 to 4, wherein the mass ratio of the polyamide resin to the polyethylene resin contained in the sanitary nonwoven fabric (polyamide resin/polyethylene resin) is 0.1 or more and 2.0 or less. non-woven fabric.
The sanitary nonwoven fabric further comprises a polyethylene resin,
The polyethylene resin includes low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), high-density polyethylene resin (HDPE), linear low-density polyethylene resin (LLDPE), and ethylene-propylene copolymer. The sanitary nonwoven fabric according to any one of claims 1 to 5, which is one or more.
The sanitary nonwoven fabric according to claim 6, wherein the fiber is a core-sheath composite fiber having a core made of polyamide resin and a sheath made of high-density polyethylene resin (HDPE).
The sanitary nonwoven fabric according to any one of claims 1 to 7, wherein the mean deviation (MMD) of the coefficient of friction is 0.010 or less.
The sanitary nonwoven fabric according to any one of claims 1 to 8, wherein the fiber assembly of the sanitary nonwoven fabric has a cool contact q max of 0.06 W/m 2 or more and 0.80 W/m 2 or less. .
The sanitary nonwoven fabric according to any one of claims 1 to 9, wherein the fiber assembly of the sanitary nonwoven fabric has a thermal conductivity of 0.08 W/mK or more.
The sanitary nonwoven fabric according to any one of claims 1 to 10, wherein the sanitary nonwoven fabric has a flexural rigidity value of 0.25 gf·cm 2 /cm or less.
The sanitary nonwoven fabric according to any one of claims 1 to 11, wherein the fibers have a fiber diameter of 1 μm or more and 40 μm or less.
The sanitary nonwoven fabric according to any one of claims 1 to 12, wherein the fibers have a fiber length of 30 mm or more and 70 mm or less.
The sanitary nonwoven fabric according to any one of claims 1 to 13, wherein the sanitary nonwoven fabric further contains a filler.
The sanitary nonwoven fabric according to claim 14, wherein the filler is one or more of titanium oxide, alumina, boron nitride, magnesium oxide, silica, carbon black, zinc oxide, and carbon nanotubes.
Having a first fiber layer made of the fiber assembly and a second fiber layer made of the second fiber assembly arranged adjacent to the first fiber layer,
The sanitary nonwoven fabric according to any one of claims 1 to 15, wherein the second fiber assembly has a compressive deformation amount of 0.3 mm or more under a load of 9.8 mN/cm 2 .
The sanitary nonwoven fabric according to claim 16, wherein the first fiber layer is arranged on the outer surface.
A sanitary nonwoven fabric according to any one of claims 1 to 17 and a second member arranged adjacent to the nonwoven fabric,
The sanitary product, wherein the second member has a compressive deformation amount of 0.3 mm or more under a load of 9.8 mN/cm 2 .
The sanitary article according to claim 18, wherein the compressive deformation amount under a load of 9.8 mN/cm 2 is 0.3 mm or more.
The sanitary article according to claim 18 or 19, wherein said second member is an absorbent body.
An absorbent article comprising the sanitary nonwoven fabric according to any one of claims 1 to 17.
The absorbent article according to claim 21, wherein the sanitary nonwoven fabric is arranged on the outer surface of the absorbent article.
A method for producing a sanitary nonwoven fabric according to any one of claims 1 to 17,
A method for producing a sanitary nonwoven fabric, comprising a step of subjecting a fiber web containing a polyamide resin to an air-through treatment or a spunbond treatment.
further comprising a step of subjecting the fiber assembly obtained by the air-through treatment or the spunbond treatment to a consolidation treatment,
24. The manufacturing method according to claim 23, wherein the consolidation treatment is performed while heating at a temperature below the melting point of the constituent resin of the fiber.
As the consolidation treatment, a press treatment is performed in which the fiber assembly is placed between two metal flat plates and pressed, or a calendering treatment is performed in which the fiber assembly is introduced between a pair of rolls and pressed. 25. The manufacturing method according to claim 24.
As the consolidation treatment, the press treatment is performed,
26. The manufacturing method according to claim 24 or 25, wherein a pressurizing condition in said press treatment is 5 MPa or more and 72 MPa or less.
As the consolidation treatment, the calendar treatment is performed,
26. The manufacturing method according to claim 24 or 25, wherein the pressurization condition in the calendering is 78.4 N/cm (8 kgf/cm) or more and 686 N/cm (70 kgf/cm) or less.