CN115427621A

CN115427621A - Sanitary nonwoven fabric, sanitary product and absorbent article provided with same, and method for producing sanitary nonwoven fabric

Info

Publication number: CN115427621A
Application number: CN202180029359.XA
Authority: CN
Inventors: 小林奈都美; 寒川裕太
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2020-04-22
Filing date: 2021-04-22
Publication date: 2022-12-02
Also published as: TW202207891A; WO2021215492A1; JP2021175498A

Abstract

The sanitary nonwoven fabric comprises fibers at least a part of the surface of which is composed of a polyethylene resin, and has a volume filling rate of 3.5% or more. Also preferred are: the fibers have a major axis and a minor axis, and the ratio of the length of the major axis to the length of the minor axis is 1.5 to 10. Also preferred are: in the nonwoven fabric, the fibers are in contact with each other at a plurality of points in a cross-sectional view. The present invention also provides an absorbent article comprising the sanitary nonwoven fabric. Further, the present invention provides a method for producing a sanitary nonwoven fabric, in which a web of fibers containing a polyethylene resin is subjected to a hot air treatment and a densification treatment on at least a part of the surface.

Description

Sanitary nonwoven fabric, sanitary product and absorbent article provided with same, and method for producing sanitary nonwoven fabric

Technical Field

The present invention relates to a sanitary nonwoven fabric, a sanitary product and an absorbent article provided with the same, and a method for producing the sanitary nonwoven fabric.

Background

Fiber sheets that can give a cool feeling and articles provided with the fiber sheets have been proposed. For example, patent document 1 discloses a comfortable fabric used for clothing for eliminating summer heat feeling. The document describes that the fabric comprises at least one organic polymer fiber having a thermal conductivity of 5W/mK or more in the fiber axial direction at 20 to 30 ℃, the thermal conductivity of the fabric in the thickness direction at 20 to 30 ℃ is 0.08W/mK or more, and the contact Wen Lianggan is 0.13W/cm ² As described above.

Patent document 2 discloses a sheet-like fiber bundle assembly having excellent cool feeling characteristics in contact therewith and used for bedding or bedding. The assembly is formed by laminating a plurality of sheets containing high molecular polyethylene fibers with the average fiber length of 10-200 mm.

The present applicant has also proposed a sheet for an absorbent article which is less likely to cause discomfort when in contact with the skin in a wet state (see patent document 3). The sheet comprises hydrophobic fibers and cellulose fibers, and has a cool feeling q in contact with both sides of the sheet in a state of a water content of 50 mass% _max Are all 2.5kW/m ² The following.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2010-236130

Patent document 2: japanese patent laid-open publication No. 2018-145577

Patent document 3: japanese patent laid-open publication No. 2019-42403

Disclosure of Invention

The invention relates to a sanitary non-woven fabric.

In one embodiment, the sanitary nonwoven fabric comprises fibers containing a polyethylene resin on at least a part of the surface thereof.

In one embodiment, the volume filling rate of the sanitary nonwoven fabric is preferably 3.5% or more.

The present invention also relates to an absorbent article provided with the sanitary nonwoven fabric.

The present invention also relates to a sanitary article comprising the sanitary nonwoven fabric.

In one embodiment, the sanitary product includes a 2 nd member disposed adjacent to the sanitary nonwoven fabric.

In one embodiment, the 2 nd member is 9.8mN/cm ² (1gf/cm ² ) The compression deformation under load is 0.3mm or more.

Further, the present invention relates to a method for producing a sanitary nonwoven fabric, which comprises subjecting a web comprising fibers of a polyethylene resin at least partially on the surface thereof to a hot air treatment to obtain a fiber aggregate.

In one embodiment, the fiber aggregate is preferably subjected to a compacting treatment.

Other features of the invention will be apparent from the scope of the claims and from the description which follows.

Detailed Description

Sanitary products such as absorbent articles for absorbing liquid discharged from the body, such as sanitary napkins and pantiliners, are configured by combining a plurality of components including nonwoven fabric, and such products, when they come into contact with the skin before use or during wearing, cause the wearer to feel a feeling of warmth and give a feeling of discomfort such as stuffiness during use. This may become more pronounced, especially in summer heat environments. Therefore, it is desirable that the sanitary product such as an absorbent article has a structure that a part in contact with the skin can feel cool.

However, the techniques described in patent documents 1 and 2 are applied to articles other than sanitary products such as clothes and bedding, and no study has been made on the application to sanitary products.

The technique described in patent document 3 is less likely to cause discomfort by contact with the skin even in a wet state, but there is still room for improvement as to how to reduce discomfort before the use of the absorbent article or before the absorption of liquid when the absorbent article is worn.

Accordingly, the present invention relates to a sanitary nonwoven fabric which gives a comfortable feeling of use by giving a cool feeling when it is brought into contact with the skin, and a sanitary article and an absorbent article provided with the same.

The present invention will be described below based on preferred embodiments of the present invention.

When an upper limit value, a lower limit value, or an upper limit value and a lower limit value of a numerical value are defined in the present specification, the upper limit value and the lower limit value themselves are also included. In addition, unless otherwise specifically stated, all values or ranges of values within a range where an upper limit value or lower limit value or upper and lower limit values of a numerical value are described are to be understood.

In the present specification, "a" or "an" and the like mean one or more than one meaning.

It is understood that various modifications and variations of the present invention can be realized by referring to the above disclosure and the following disclosure in the present specification. Therefore, it is understood that the present invention can be carried out in the embodiments not explicitly described in the present specification within the technical scope based on the contents of the claims.

The entire contents of the above patent documents and the following patent documents are incorporated in the present specification as a part of the contents of the present specification.

The sanitary nonwoven fabric of the present invention is suitably used as a constituent member of sanitary goods. Typical examples of the sanitary products include sanitary products such as face masks and eye masks, and absorbent articles that absorb body fluids such as urine and menstrual blood.

The sanitary nonwoven fabric is disposed on the skin contact surface side which is the surface in contact with the skin of the wearer when the sanitary product is worn, or is disposed in a portion in contact with the hand of the user or the like when the sanitary product is disposed.

The sanitary nonwoven fabric can be used without particular limitation to the uses described herein.

The sanitary nonwoven fabric of the present invention is a fibrous sheet comprising fibers containing a polyethylene resin at least partially on the surface thereof, and is preferably composed of only the fibers.

The fibers constituting the sanitary nonwoven fabric maintain the form of the fiber sheet by at least one of entanglement, fusion, and pressure bonding. Therefore, the sanitary nonwoven fabric of the present invention is configured to mainly include a form in which boundaries between constituent fibers in contact with each other are clear.

The fibers contained in the sanitary nonwoven fabric have a polyethylene resin on at least a part of the fiber surface. Examples of the presence of the polyethylene resin as the fiber contained in the sanitary nonwoven fabric of the present invention include the following: (i) A mode in which the outer surface and the inside of the fiber contain a polyethylene resin, that is, a mode in which the constituent resin of the fiber is only a polyethylene resin; or (ii) a two-component composite fiber comprising a low-melting-point component containing a polyethylene resin and a high-melting-point component having a higher melting point than the low-melting-point component, wherein the low-melting-point component is continuously present on at least a part of the fiber surface in the longitudinal direction.

It is generally known that a polyethylene resin has particularly high thermal conductivity among organic polymer materials. Therefore, from the viewpoint of suppressing a decrease in thermal conductivity due to an interface formed between the polyethylene resin and a resin other than the polyethylene resin while exhibiting high thermal conductivity of the polyethylene resin itself, and giving a cool feeling to a user, the above-described aspect (i) is preferably employed.

Specific examples of the above (i) include: fibers containing a single type of polyethylene resin as a constituent resin, or fibers containing only a plurality of types of polyethylene resins as a constituent resin. Specific examples of the above-mentioned (ii) include (a) core-sheath fibers in which a resin other than polyethylene resin as a high-melting-point component is used as a core and a sheath of polyethylene resin as a low-melting-point component is formed so as to cover the surface of the core, and (b) side-by-side fibers in which polyethylene resin as a low-melting-point component is used as a low-melting-point component and a resin other than polyethylene resin is used as a high-melting-point component, and polyethylene resin as a low-melting-point component is continuously present on at least a part of the surface of the fibers along the longitudinal direction of the fibers. The fibers used in the present invention may be solid or hollow. From the viewpoint of improving the thermal conductivity and making the user feel cool, the solid fiber is preferable.

In the mode of presence of the polyethylene resin in the fiber, the polyethylene resin is preferably present over at least the entire outer surface of the fiber, and the entire fiber is preferably formed of the polyethylene resin. That is, a fiber having a core-sheath structure in which a polyethylene resin is used as a sheath, or a solid fiber containing only a polyethylene resin is preferable. With this configuration, the polyethylene resin having high thermal conductivity is in direct contact with the skin of the user, and therefore the user can feel a cool feeling strongly.

In particular, the fibers present in the sanitary nonwoven fabric are more preferably fibers containing only a polyethylene resin as a constituent resin thereof. By using only the polyethylene resin having high thermal conductivity, the fibers can be easily configured to have high thermal conductivity, and thus the user can feel a cool feeling more strongly.

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), ethylene-propylene copolymer, and the like. These may be used alone or in combination of plural kinds.

When an ethylene-propylene copolymer is used as the polyethylene resin, the proportion of ethylene units in the copolymer is preferably 95% by mass or more, and more preferably 98% by mass or more, from the viewpoint of improving the thermal conductivity.

The proportion of the propylene unit in the copolymer is preferably 5% by mass or less, and more preferably 2% by mass or less.

Examples of the fibers containing only a polyethylene resin include: fibers containing only HDPE (i.e., fibers in which 100 mass% of HDPE is used), or core-sheath fibers or side-by-side fibers using a plurality of the above-mentioned various polyethylenes.

Examples of the core-sheath fiber or side-by-side fiber using only a polyethylene resin include: the core and the sheath are made of HDPE fibers having different melting points, core-sheath fibers having HDPE as the core and HDPE as the sheath, HDPE as the core and LLDPE as the sheath, or side-by-side fibers having HDPE continuously present in the longitudinal direction on at least a part of the surface of the fiber made of LLDPE.

In the fibers containing only the polyethylene resin, the kind or combination of the polyethylene resin may be adopted without being limited to the above.

Among these, from the viewpoint of having physical properties of high thermal conductivity and making the user feel cool more strongly, the polyethylene resin preferably contains HDPE, and more preferably contains only HDPE. That is, it is more preferable to use HDPE alone.

Examples of the resin other than the polyethylene resin used in the present invention include: polyolefin resins other than polyethylene resins such as polypropylene (PP) and polybutylene; polyester resins such as polyethylene terephthalate (PET); a polyamide resin; vinyl resins such as polyvinyl chloride and polystyrene; acrylic resins such as polyacrylic acid and polymethyl methacrylate; fluorine resins such as fluorinated ethylene; and nylon, and the like. These resins may be used singly or in combination of two or more.

The content of the polyethylene resin is preferably 70% by mass or more, more preferably 80% by mass or more, further preferably 90% by mass or more, further preferably 100% by mass or less, and particularly preferably 100% by mass, based on the total mass of the resins contained in the sanitary nonwoven fabric.

In another embodiment of the nonwoven fabric for hygiene of the present invention, the nonwoven fabric for hygiene preferably contains fibers having a thermal conductivity of a predetermined value or more in at least a part of the surface.

Specifically, the sanitary nonwoven fabric preferably contains fibers having a thermal conductivity of preferably 0.11W/mK or more, more preferably 0.13W/mK or more, and still more preferably 0.15W/mK or more in a part of the surface.

In reality, the sanitary nonwoven fabric contains fibers having a thermal conductivity of 0.4W/mK or less in a part of the surface thereof.

The thermal conductivity can be measured, for example, by melting a sanitary nonwoven fabric into a form of a film sample having a thickness of about 1 mm. The detailed measurement method will be described below.

By having such a thermal conductivity, a user of a sanitary product including the sanitary nonwoven fabric can feel a cool feeling more strongly.

The configuration related to thermal conductivity in this embodiment mode may be used instead of or in combination with the above embodiment mode.

Note that, in the present embodiment, the description of the above embodiment and the respective configurations can be applied as appropriate to the aspects not described.

The sanitary nonwoven fabric having the thermal conductivity can be obtained by, for example, being configured to contain, as a constituent fiber, a fiber containing one or two or more of the polyethylene resins used in the above-described embodiments.

In this case, the thermal conductivity of at least a part of the surface constituting the fiber is preferably 0.11W/mK or more, more preferably 0.13W/mK or more, and still more preferably 0.15W/mK or more. The use of fibers having such thermal conductivity is preferable because the thermal conductivity of the sanitary nonwoven fabric can be easily achieved within a range.

In addition, the above-described thermal conductivity of the constituent fibers can be easily achieved by using fibers containing only a polyethylene resin, for example.

The thermal conductivity can be measured, for example, by the following method. First, a nonwoven fabric or fibers to be measured are peeled off from a product by cold spraying or the like, or fibers are sampled and separated. Then, the separated nonwoven fabric or fiber is introduced into a heating and pressing device such as a press, and heated and pressed at a temperature equal to or higher than the melting point of the nonwoven fabric or fiber material to prepare a film-like sample having a thickness of about 1 mm. At this time, the pressurizing conditions are appropriately adjusted so that air does not remain in the sample.

Then, using a steady-state thermal conductivity measuring apparatus (KES-F6, manufactured by gaku corporation), the thermal conductivity was measured based on the amount of heat transfer from a hot plate at 30 ℃ to a hot plate at 20 ℃ via a sample. The measurement was performed for 10 sites on one film-shaped sample, and the highest thermal conductivity among these was taken as the thermal conductivity (W/mK) in the present invention.

The sanitary nonwoven fabric of the present invention has a volume filling ratio of preferably 3.5% or more, more preferably 7.0% or more, further preferably 10.0% or more, further more preferably 14.0% or more, and particularly preferably 20.0% or more, from the viewpoint of reducing the content of air having low thermal conductivity to improve the thermal conductivity of the nonwoven fabric.

In the case of using the material for disposable hygiene in contact with the skin of the user, the volume filling ratio is preferably 60.0% or less, more preferably 50.0% or less, and still more preferably 30.0% or less, from the viewpoint of improving the texture.

By having the above volume filling ratio, the content of air having low thermal conductivity is reduced in the sanitary nonwoven fabric, so that heat transferability can be improved, thereby making it possible to make the user feel cool more strongly.

In addition, the texture of the fiber sheet and the sanitary article in which the sheet is embedded can be sufficiently expressed.

The above-described structure can be obtained by, for example, subjecting a fiber sheet to an operation such as compression as in the following production method. When the sanitary nonwoven fabric has a density gradient, the volume filling ratio of the outermost layer that is in contact with the skin of the user may be within the above range.

The above-described configuration relating to the volume filling ratio can be applied to various embodiments of a sanitary nonwoven fabric including fibers having a surface at least partially containing a polyethylene resin, a sanitary nonwoven fabric having a thermal conductivity of a surface of a constituent fiber of a predetermined value or more, and a sanitary nonwoven fabric having a thermal conductivity of a nonwoven fabric of a predetermined value or more.

The volume fill ratio in the present invention can be expressed as a percentage of the apparent volume relative to the actual volume. Specifically, a predetermined area of the sanitary nonwoven fabric to be measured is cut out to obtain a measurement sample, and the mass (g) thereof is measured. The predetermined area when the measurement sample is cut out is preferably 10cm square, but if the measurement sample having the size cannot be cut out, the measurement sample is cut out again in a region where the weight per unit area is uniform by visual observation of the sanitary nonwoven fabric as the measurement target, with the width and length of the region being as large as possible. Then, the user can use the device to perform the operation,the weight per unit area A (g/cm) of the measurement sample was calculated ² )。

The thickness B (cm) of the sample is measured by the following method. First, only a 12.59g (diameter 55 mm) plate was mounted on a laser displacement meter (LK-080 manufactured by keyence corporation), and zero point adjustment was performed with the measured thickness set to zero. Then, the above sheet was placed on a measurement sample, and the thickness in this state was measured using a laser displacement meter, and the thickness was set as the thickness B (cm) of the measurement sample. In the measurement of the thickness B, a plate was placed on the test piece to give 4.9mN/cm ² The load of (2).

Further, the density C (g/cm) of the constituent components of the fiber is used ³ ) The volume filling ratio (%) was calculated according to the following formula.

Volume filling ratio (%) =100 × (a)/(B × C)

When a sanitary nonwoven fabric to be measured is put into a sanitary product such as an absorbent article, a cold spray is blown to the sanitary product to cure the hot-melt adhesive, and thereafter the sanitary nonwoven fabric to be measured is carefully peeled off. This method is also common to other assays in this specification.

In the sanitary nonwoven fabric having the above-described configuration, since the fibers having the polyethylene resin having high thermal conductivity among the synthetic resins are used at least in a part of the surface, when the fibers are in contact with the skin of the user, heat caused by the body temperature of the user can be rapidly transferred from the user to the sanitary nonwoven fabric or other fibers not in contact with the user.

Further, by setting the volume filling rate of the sanitary nonwoven fabric within a predetermined value range, it is possible to exhibit good texture of the fiber sheet and reduce the content of air having low thermal conductivity in the sanitary nonwoven fabric, so that heat generated from the user can be quickly transferred to the sanitary nonwoven fabric side.

As a result, when the skin of the user comes into contact with the sanitary nonwoven fabric, the user can feel a cool feeling and the comfortable use feeling can be provided by the cool feeling.

According to a preferred embodiment of the present invention, the user can feel a cool feeling more strongly, and therefore, the feeling of use can be further improved.

Further, by configuring the sanitary nonwoven fabric in a form including fibers, the contact area when the skin of the user comes into contact with the sanitary nonwoven fabric can be increased, the user can feel cool, and the softness due to the configuration of the nonwoven fabric can be expressed.

The fibers constituting the sanitary nonwoven fabric are preferably in contact with each other, and more preferably in contact with each other at a plurality of points. This enables heat generated by contact with the skin of the user to be transmitted in multiple directions, and therefore, heat generated by the body temperature of the user can be efficiently transferred, and as a result, the user can feel a cool feeling more efficiently.

The "contact" in the present invention includes two modes, i.e., a mode in which fibers are in contact with each other in a state in which the boundary between the fibers is clear; and a manner in which there are portions where the fibers are fused to each other, whereby the interface between the fibers becomes unclear.

The term "multipoint contact" in the present invention means that when a nonwoven fabric is cut in a direction orthogonal to the extending direction of its constituent fibers and any fiber F on the cut surface is observed, the upper and lower fibers located in the thickness direction of the nonwoven fabric and in contact with the fiber F are in contact with the fiber F at 2 or more points.

The structure in which the fibers are in contact with each other at a plurality of points can be obtained by, for example, subjecting a raw material nonwoven fabric to a compacting treatment by compression or the like in the following production process using the below-described fibers having a non-circular cross-sectional shape such as an oval shape or a multilobal shape.

In the case where the fibers of the sanitary nonwoven fabric are in contact with each other, the contact is preferably formed by fusion or pressure bonding. With this configuration, the contact area between the fibers can be increased, and the heat transfer efficiency can be further improved. As a result, the user can be efficiently provided with a cool feeling.

The fusion is a method in which heat is applied only to a plurality of fibers or heat and pressure are applied to the plurality of fibers to melt the fibers, thereby making the boundaries between the fibers unclear.

The crimping is a method of applying only pressure to a plurality of fibers to allow gaps formed between the fibers to exist so that the fibers are in contact with each other with the boundaries between the fibers being clear. In the crimping, the above-described "multipoint contact" method is also preferable.

The cross-sectional shape of the fibers constituting the sanitary nonwoven fabric includes, for example: circular, elliptical, etc.; triangular, quadrangular, pentagonal, hexagonal and other convex polygons or regular polygons. In addition to these geometric shapes, the shape may be a multi-lobed shape having a structure in which a plurality of concave portions and convex portions are formed along the outer circumference of the cross section.

The "cross-sectional shape" in the present invention refers to a shape of fibers constituting the sanitary nonwoven fabric, which is observed when a cross section perpendicular to the extending direction of the fibers is observed.

The cross-sectional shape of the fiber is preferably a shape having a major axis and a minor axis, such as a non-perfect circle, more preferably an ellipse, or a combination of an ellipse and a multilobal shape. By adopting such a shape, the volume filling rate of the sanitary nonwoven fabric can be easily increased, and the number of contact points and the contact area between the fibers can be increased, thereby further improving the heat transfer efficiency, and thus making it possible to more effectively provide a cool feeling to the user.

When the cross-sectional shape of the fiber has a major axis and a minor axis, the ratio of the major axis length to the minor axis length (major axis length/minor axis length) is preferably 1.5 or more, more preferably 2 or more, and even more preferably 3 or more.

In addition, from the viewpoint of improving the spinnability in the production of fibers and improving the production efficiency, the ratio is preferably 10 or less, more preferably 8 or less, and still more preferably 5 or less.

Further, the above ratio is preferably satisfied over the entire length of the fiber.

The lengths of the major axis and the minor axis of the cross-sectional shape of the fiber can be measured, for example, by the following methods. First, a nonwoven fabric to be measured is cooled with liquid nitrogen, and then cut by a cutter in a direction perpendicular to the fiber length direction to prepare a measurement sample. The cross section of the measurement sample was observed using a Scanning Electron Microscope (SEM) with an arbitrary magnification sufficient to identify the fiber cross section and measure the size of the fiber cross section.

Each cross section was observed independently for 10 arbitrary fibers, and 2 points on the periphery of the cross section of each fiber were connected based on a scanning electron microscope image of each fiber, and a line segment having a maximum diameter length passing through the centroid of the cross section of the fiber was defined as a major axis, and a maximum width of a minor axis orthogonal to the major axis was defined as a minor axis (in the case of a deformed cross-sectional shape having a plurality of irregularities on the outer periphery, the minimum width of the minor axis corresponding to the concave portion was not considered). The arithmetic mean of these is defined as the major axis length or the minor axis length in the present invention.

When the cross-sectional shape of the fiber is a deformed cross-sectional shape having a plurality of irregularities on the outer periphery, such as a multilobal shape, ellipse approximation processing is performed based on the periphery of the fiber cross-section using image processing software or the like from a scanning electron microscope image of each fiber cross-section obtained for any 10 fibers. The arithmetic average value calculated based on the respective lengths of the major axis and the minor axis of the ellipse obtained by the processing is defined as the major axis length or the minor axis length in the present invention.

From the viewpoint of improving the texture of the nonwoven fabric, the thickness of the nonwoven fabric for hygiene of the present invention is preferably 0.1mm or more, more preferably 0.2mm or more, and further preferably 0.3mm or more.

The thickness of the sanitary nonwoven fabric of the present invention is preferably 3mm or less, more preferably 1.5mm or less, and even more preferably 0.5mm or less, from the viewpoint of reducing the air content in the nonwoven fabric to improve the thermal conductivity.

The thickness of the sanitary nonwoven fabric is set to be 4.9mN/cm ² (0.5gf/cm ² ) Measured under load using a laser displacement meter or the like.

By making the thickness of the sanitary nonwoven fabric the above-mentioned constitution, the thermal capacity of the sanitary nonwoven fabric can be increased, and the sanitary nonwoven fabric which can give a cool feeling to the user can be efficiently produced.

In addition, the present inventionThe weight per unit area of the sanitary nonwoven fabric of (2) is preferably 15g/m ² Above, more preferably 20g/m ² Above, it is more preferably 25g/m ² The above.

The sanitary nonwoven fabric of the present invention preferably has a basis weight of 140g/m ² Hereinafter, more preferably 90g/m ² Hereinafter, it is more preferably 50g/m ² The following.

With the above configuration, the difference in cool feeling due to the variation in the basis weight of the sanitary nonwoven fabric can be reduced, and the fibers can be effectively fused and densified, whereby the sanitary nonwoven fabric having a predetermined volume filling rate can be manufactured with high productivity.

The sanitary nonwoven fabric of the invention has cool feeling q _max Preferably 0.06W/m ² Above, more preferably 0.08W/m ² Above, more preferably 0.10W/m ² Above, and preferably 0.80W/m ² The lower limit is more preferably 0.60W/m ² It is more preferably 0.50W/m or less ² The following.

Specifically, the sanitary nonwoven fabric has a cool feeling q _max Preferably 0.06W/m ² Above and 0.80W/m ² It is more preferably 0.08W/m or less ² Above and 0.60W/m ² It is more preferably 0.10W/m or less ² Above and 0.50W/m ² The following.

Cool feeling of contact q _max The measurement can be carried out, for example, by the following method.

First, a test piece was cut out of a sanitary nonwoven fabric to be measured so as to have a length of 10cm × a width of 10cm, and the test piece was left to stand at room temperature of 23 ℃ and a relative humidity of 50% for 24 hours.

Then, in this environment, the test piece was placed on the measurement stand, and the test piece was fixed to the measurement stand using a double-sided adhesive tape. A thermostat device using gas or liquid as a heat medium was used as the measurement table.

Then, the contact with the object to be measured was carried out by a measuring apparatus (KES-F7 Thermo Lab II manufactured by Kyoto Co., ltd.) in accordance with the measurement instructions of the apparatusCool feeling q _max And (4) carrying out measurement.

Specifically, the usable area is 9.0cm ² And a pure copper plate having a mass of 9.8g as a hot plate to be brought into contact with the measurement object, the initial temperature of the copper plate was set to 33 ℃ (10 ℃ higher than the surface temperature of the measurement object), the contact pressure of the copper plate and the measurement object was set to 1kPa, the copper plate was brought into contact with the test piece, the value of the heat flow rate at the moment of the contact was set to zero, and the maximum value of the heat flow rate was measured.

The measurement was performed 5 times on each surface of the object to be measured, and the arithmetic average of the obtained measured values was defined as the cool feeling q of contact of the object to be measured _max (W/m ² )。

The cool-touch feeling is a value obtained by numerically expressing a skin feeling that feels cool when the skin touches an object. The cool feeling upon contact differs depending on the amount of heat transfer from the skin to the object when the skin comes into contact with the object, and the more the amount of heat transfer is, the cooler the skin feels upon contact. Cool feeling of contact q _max A cool feeling q is given to the skin corresponding to the maximum value of the heat transfer amount from the skin to the object _max The value of (2) is larger as the contact with the object is cooled, and is smaller as the contact with the object is warmed. Thus, by making the contact cool q _max The value of (b) is within the above range, the cool feeling can be more effectively felt.

The sanitary nonwoven fabric of the present invention is a sheet-like article having 2 faces, and it is preferable that the proportion of the constituent fibers (hereinafter, also referred to as "fiber surface proportion") on the surface of the sanitary nonwoven fabric be a predetermined value or more. The surface of the sanitary nonwoven fabric is a region from the outermost surface of the sanitary nonwoven fabric to a distance of20 μm from the surface in the thickness direction. The outermost surface of the sanitary nonwoven fabric means a surface perpendicular to the thickness direction of the sanitary nonwoven fabric, which is formed by a portion located on the outermost side in the thickness direction in an image obtained by cutting the sanitary nonwoven fabric in the thickness direction and observing the cross section in the thickness direction using a Scanning Electron Microscope (SEM).

Specifically, the fiber surface presence ratio of the sanitary nonwoven fabric is preferably 40% or more, more preferably 45% or more, and still more preferably 50% or more, and preferably 90% or less, more preferably 85% or less, and still more preferably 80% or less.

More specifically, the fiber surface presence ratio of the sanitary nonwoven fabric is preferably 40% or more and 90% or less, more preferably 45% or more and 85% or less, and still more preferably 50% or more and 80% or less.

The fiber surface presence ratio is a ratio indicating a relationship between the constituent fibers and the gaps between the fibers on the surface of the nonwoven fabric, in view of the presence ratio of the fibers. Therefore, when the fiber surface existence rate is in the above range, the air content in the fiber can be reduced, and a higher cool feeling can be obtained.

The fiber surface presence ratio can be measured as a ratio on an area basis, for example, by the following method.

Specifically, 2 sites were randomly sampled from a sanitary nonwoven fabric to be measured in 4cm × 4cm sections. One surface of the obtained sample was measured under the conditions of a voltage of 15kV and a magnification of 50 times using a Scanning Electron Microscope (SEM), and an SEM image was obtained. Then, the SEM image was binarized into the threshold values of 121 to 255 using image processing software WinROOF2018 (manufactured by sambucus corporation), and the ratio of the area of the bright (white) portion after binarization to the area of the entire image area was measured and calculated using the area calculation function built in the software, and the area ratio was set as the fiber surface existence rate of the present invention.

When it is difficult to measure by the above method, the area ratio of the bright portion is measured by binarizing the threshold value to a value of 70 to 255.

The sanitary nonwoven fabric of the present invention is preferably arranged such that the fibers constituting the nonwoven fabric have a certain orientation.

With this configuration, heat is easily transferred in the longitudinal direction of the fibers, and the user can easily feel a cool feeling.

More specifically, in the sanitary nonwoven fabric of the present invention, when the nonwoven fabric is left standing on a horizontal plane, the fiber length direction of the fibers of the nonwoven fabric is preferably substantially parallel to the horizontal plane.

In addition, in addition to or instead of this, the sanitary nonwoven fabric preferably has one direction of fiber extension in a plan view. For example, when considering the 1 st direction and the 2 nd direction orthogonal to the 1 st direction of the sanitary nonwoven fabric in a plan view of the sanitary nonwoven fabric, it is more preferable that the extending direction of the fibers is aligned with the 1 st direction or the 2 nd direction of the nonwoven fabric. When the fibers have intersections, it is desirable that the angle formed by the fibers having intersections be 50% or more of the obtuse angle in a plan view of the sanitary nonwoven fabric. By obtuse angle is meant an angle greater than 90 deg..

For the quantification of the angle formed by the fibers, the sanitary nonwoven fabric may be photographed by SEM at a magnification at which the intersection of the fibers at about 10 points in the visual field is observed at any 3 points of the sanitary nonwoven fabric, and the obtained image data may be measured and counted by image analysis software attached to the SEM or any image analysis software. In addition, in the case where the image analysis software is not provided, the obtained image data may be printed, the angles of the fibers may be checked by an angle measuring device such as a protractor, and the angles may be counted by writing the angles into a data table.

By having at least one of the above-described configurations relating to the orientation of the fibers, the heat transfer can be easily advanced in a certain direction, and the user can be more effectively made to feel a cool feeling.

Such a configuration can be obtained, for example, by producing a long sheet using short HDPE fibers as a material, conveying the long sheet while applying tension to the long sheet in the conveying direction, fusing the fibers to each other by a hot air method, or conveying the fibers in one direction while spinning out the HDPE fibers to a conveying device such as a belt conveyor.

In the above description, for convenience of explanation, a mode in which the sanitary nonwoven fabric has a single fiber layer and the single fiber layer contains fibers containing a polyethylene resin at least partially on the surface (whether the sanitary nonwoven fabric contains only a single fiber or is blended with other fibers) has been described as an example, but the present invention is not limited to this mode. Specifically, the sanitary nonwoven fabric may have a plurality of fiber layers of2 or more layers.

As one embodiment of the sanitary nonwoven fabric, for example, at least: the polyethylene resin composition comprises a fiber layer containing 1 st fibers (hereinafter, also referred to as a 1 st fiber layer) having at least a part of the surface thereof containing a polyethylene resin, and a layer containing 2 nd fibers (hereinafter, also referred to as a 2 nd fiber layer) containing fibers other than the 1 st fibers, which is arranged adjacent to the fiber layer. The term "adjacent" as used herein means that the fiber layers are adjacent to each other without interposing other fiber layers therebetween, but an adhesive is allowed to intervene between the fiber layers.

In this case, from the viewpoint of more effectively feeling cool, the 1 st fiber layer preferably constitutes the outer surface of the sanitary nonwoven fabric. From the same viewpoint, at least the 1 st fiber layer preferably satisfies various preferred embodiments relating to the sanitary nonwoven fabric, and more preferably satisfies the preferred embodiments in the entire sanitary nonwoven fabric.

Specifically, the sanitary nonwoven fabric having a multilayer structure can be obtained, for example, by subjecting a web containing 1 st fibers at least a part of the surface of which is composed of a polyethylene resin and a 2 nd web containing fibers other than the 1 st fibers to hot air processing or spun bonding processing in a state of being laminated. In this case, the boundary between the fiber layers is not always clear, but may include a portion where the boundary is clear. In the case of this embodiment, the fiber layers maintain the form of the fiber sheet by at least one of entanglement, fusion, and pressure bonding, for example.

Another embodiment of the nonwoven fabric for sanitary use having a multilayer structure includes a mode in which a fiber web or a fiber sheet containing 1 st fibers at least a part of the surface of which is composed of a polyethylene resin is bonded to a fiber web or a fiber sheet containing fibers other than the 1 st fibers with an adhesive to maintain the fiber sheet. In this case, the interface of the individual fiber layers is usually clear.

In any case, the fibers other than the 1 st fiber include not only fibers containing the above-described constituent resins such as PET resin and PP resin, but also one or more of pulp fibers, rayon fibers, fibers subjected to hydrophilization treatment, and the like.

The weight per unit area of the 2 nd fiber layer is preferably 15g/m ² Above, more preferably 20g/m ² Above, it is more preferably 25g/m ² The above is preferably 140g/m ² Hereinafter, more preferably 90g/m ² Hereinafter, more preferably 70g/m ² The following.

The sanitary nonwoven fabric may be used as it is, or a sanitary product provided with the sanitary nonwoven fabric may be produced by using the sanitary nonwoven fabric as a constituent member of the sanitary product.

When the sanitary nonwoven fabric of the present invention is incorporated into a sanitary product, the nonwoven fabric preferably constitutes a surface facing the skin of the user.

In either case, typically, it is disposable.

The sanitary article provided with the sanitary nonwoven fabric of the present invention is, for example, an absorbent article. That is, the sanitary nonwoven fabric can be used as a constituent member of an absorbent article or the like.

Typically, an absorbent article includes a front sheet and a back sheet, and an absorbent body disposed between the front sheet and the back sheet, and may be used in a state where a sanitary nonwoven fabric is disposed in addition to the front sheet and the back sheet, or in a state where the sanitary nonwoven fabric is disposed in place of the front sheet or the back sheet. Examples of the absorbent article include, but are not limited to, disposable diapers, urine leakage pads, menstrual napkins, panty liners, and the like, and articles for absorbing liquid discharged from the human body are widely included.

When the sanitary nonwoven fabric is used as a component of an absorbent article or the like, the sanitary nonwoven fabric can be disposed in a place that is in direct contact with the skin of the user when the sanitary product such as an absorbent article is used or when the sanitary product such as an absorbent article is taken out of a package or the like. That is, the sanitary nonwoven fabric is preferably disposed on the outer surface of the sanitary product such as an absorbent article.

The outer surface of the sanitary product such as an absorbent article means a surface (including the front surface and the back surface, and the surface side in the thickness direction rather than the inner surface) of the sanitary product such as an absorbent article which can be touched by a user's hand after the package is opened and the sanitary product such as an absorbent article is taken out.

That is, the sanitary nonwoven fabric constituting the sanitary product may be disposed on a surface facing the skin of the wearer wearing the sanitary product, may be disposed on a surface not facing the skin of the wearer wearing the sanitary product, or may constitute a package of the sanitary product.

More specifically, when a sanitary nonwoven fabric is used in an absorbent article, for example, a disposable diaper, which is an embodiment of a sanitary product, it can be used as a component member, for example, a topsheet, a side nonwoven fabric, a waist gather, a gather disposed near a groin portion, an outer cover, and the like.

In addition, when the sanitary nonwoven fabric is used for an absorbent article, such as a panty liner or a sanitary napkin, which is one embodiment of a sanitary product, it can be used as a front sheet, a side nonwoven fabric, a hip protector, a pouch for single packaging, or the like.

In addition, when the sanitary nonwoven fabric is used in an absorbent article, such as a leakage pad and a sanitary napkin, which is one embodiment of a sanitary product, it can be used as a front sheet or a component member such as a wrinkle disposed near a groin portion.

In particular, from the viewpoint of reducing discomfort due to stuffiness and the like by feeling cool when using a sanitary product such as an absorbent article, it is preferable that the sanitary nonwoven fabric is disposed so as to constitute a surface (hereinafter, also referred to as "skin-facing surface") side facing the skin of a wearer wearing the sanitary product such as an absorbent article when the sanitary product is worn at a correct position.

It is also preferable that the sanitary nonwoven fabric is disposed at a portion where the sanitary product of the absorbent article directly contacts the skin of the wearer when worn.

Examples of the constituent members of such an absorbent article include: a front sheet, a side nonwoven fabric, a waist gather, a gather disposed near a groin portion, and the like.

The topsheet used in the absorbent article is a sheet constituting the skin-facing surface side, and the backsheet is a sheet constituting the surface facing the opposite side of the skin of the wearer wearing the absorbent article (hereinafter, this is also referred to as "non-skin-facing surface"). When the material other than the sanitary nonwoven fabric of the present invention is used for the front sheet and the back sheet used in the absorbent article, the material conventionally used for the absorbent article can be used, and is not particularly limited. As the topsheet, various nonwoven fabrics, apertured films, and the like having liquid permeability can be used, for example. As the back sheet, a sheet having poor liquid permeability, or having hydrophobicity or liquid permeability can be used. The former includes: resin films, laminates of resin films and nonwoven fabrics, and the like. The latter may be the same as the front sheet.

An absorbent body used for an absorbent article includes an absorbent core. The absorbent core is composed of, for example, a fiber stack of hydrophilic fibers such as cellulose typified by pulp, a mixed fiber stack of the hydrophilic fibers and a water-absorbent polymer, a stack of a water-absorbent polymer, and the like, and typically includes hydrophilic fibers and a water-absorbent polymer.

The absorbent core may also be covered by a core-spun sheet. As a covering method of the core-covering sheet, for example, at least the skin-facing surface may be covered with a liquid-permeable core-covering sheet, or the entire surface including the skin-facing surface and the non-skin-facing surface may be covered with a core-covering sheet. As the core-spun sheet, for example, a sheet paper containing hydrophilic fibers, a nonwoven fabric having liquid permeability, or the like can be used.

From the viewpoint of avoiding the fibers from entangling the skin and ensuring a good feeling to the user, the fiber diameter of the fibers used in the sanitary nonwoven fabric is preferably 3 μm or more, and more preferably 5 μm or more.

In addition, the fiber diameter of the fibers used for the sanitary nonwoven fabric is preferably 70 μm or less, more preferably 50 μm or less, from the viewpoint of reducing the fiber gaps in the nonwoven fabric, reducing the air content in the nonwoven fabric, and improving the thermal conductivity.

The fiber diameter of the fiber was measured by preparing a measurement sample and performing SEM observation in the same manner as the method of measuring the lengths of the major axis and the minor axis of the cross-sectional shape of the fiber, and the fiber diameters of 10 fibers were measured for 1 sample, and the arithmetic average thereof was set as the fiber diameter of the present invention. When the fibers are non-perfect circles, the lengths of the major axis and the minor axis of the fibers are measured by the above-described method, and the arithmetic average of the major axis length and the minor axis length of one fiber is defined as the fiber diameter, and the arithmetic average of the diameters of 10 fibers is defined as the fiber diameter of the fiber of the present invention.

The sanitary nonwoven fabric of the present invention may further contain a filler for improving thermal conductivity as long as the effects of the present invention can be exerted. Examples of such fillers include: at least one of titanium oxide, aluminum oxide, boron nitride, magnesium oxide, silicon dioxide, carbon black, carbon nanotubes, and the like. The filler may be present in the fibers, may be present between the fibers, may be present in a state where a part of the surface of the fibers is exposed, and may be present in a state where the fiber is embedded in the fiber.

When the sanitary nonwoven fabric of the present invention is used to produce a sanitary product, the sanitary product may further include another member (hereinafter, this member is also referred to as a "2 nd member") in addition to the sanitary nonwoven fabric (hereinafter, for convenience of description, this is also referred to as a "1 st fiber assembly") which is an assembly of fibers containing a polyethylene resin at least a part of the surface thereof.

As an embodiment of the sanitary product in which the member 2 is disposed, at least one of an absorbent sheet containing an absorbent polymer and fibers, an absorbent body containing an absorbent polymer and fibers, and the like can be used as the member 2. These are examples of fiber assemblies different from sanitary nonwoven fabrics. The sanitary article comprising these 2 nd members is preferably the absorbent article described above.

That is, in the present embodiment, the sanitary nonwoven fabric as the 1 st fiber assembly and the absorbent sheet and/or the absorbent body as the 2 nd member are disposed as the constituent materials of the sanitary product. The 1 st fiber aggregate and the 2 nd member are also preferably arranged adjacent to each other. The fiber assemblies in the present embodiment may or may not be joined to each other.

As the absorbent sheet, for example, an absorbent sheet described in japanese patent application laid-open No. 8-246395 or the like can be used.

When the sanitary article includes the 2 nd member or the sanitary nonwoven fabric includes the 2 nd fiber layer, it is preferable to use a member having a thickness variation of a predetermined value or more for the 2 nd member or the 2 nd fiber layer.

In detail, the 2 nd member was 9.8mN/cm ² (1gf/cm ² ) The amount of compression set under load is preferably 0.3mm or more, more preferably 0.5mm or more. The amount of compression deformation of the 2 nd member under this load is preferably 3mm or less. The amount of change in compression was determined as the thickness of the No. 2 member under no load minus 9.8mN/cm as described below ² (1gf/cm ² ) The amount of change in thickness of the 2 nd member under load is expressed.

It is preferable that the 2 nd fiber layer constituting the sanitary nonwoven fabric has the same compression set. In the case where the sanitary product includes both the sanitary nonwoven fabric having a multilayer structure and the 2 nd member, it is preferable that both the 2 nd member and the 2 nd fiber layer satisfy the above-described compression deformation amount.

With this configuration, when the 1 st fiber aggregate containing fibers at least a part of which contains a polyethylene resin on the surface is in contact with the wearer, the 1 st fiber aggregate is easily deformed following the deformation of the 2 nd member, so that the contact area with the wearer can be increased, and the wearer can efficiently feel a cool feeling.

The 2 nd fiber layer having the above physical properties can be obtained by, for example, using a fiber containing PET resin or PP resin, or a PET/HDPE core-sheath composite fiber or the like as a constituent fiber in the following production method, subjecting the constituent fiber to hot air treatment to obtain a fiber web, and using the fiber web to obtain the 2 nd fiber layer.

In the case where the 2 nd member is an absorbent sheet or an absorbent body, for example, the absorbent sheet or the absorbent body can be obtained by appropriately adjusting the basis weights of the fibers, the fibrous sheet, and the water-absorbent polymer constituting the absorbent sheet or the absorbent body.

The thickness of the 2 nd member or the 2 nd fiber layer can be measured, for example, by the following method.

First, it was confirmed by visual observation or SEM observation of the cross section of the object to be measured, observation of the fiber diameter, the distance between fibers, or the boundary between members, and the like, whether there was a sanitary nonwoven fabric having a plurality of fiber layers or there was a sanitary nonwoven fabric and a 2 nd member other than the sanitary nonwoven fabric.

When the object to be measured is a sanitary product, after the structure is fixed by, for example, immersing the sanitary product in liquid nitrogen, the sanitary nonwoven fabric and the 2 nd member other than the sanitary nonwoven fabric are carefully peeled off from the sanitary product to be measured and separated. Then, the separated member was used for a contact cooling feeling q described in detail in the following examples _max Measurement of (a) q _max The fibrous sheet having the highest value of (2) is referred to as a sanitary nonwoven fabric, and the member adjacent to the sanitary nonwoven fabric is referred to as a 2 nd member.

Then, the plate was placed on the plate, and 9.8mN/cm was added to the separated 2 nd member ² (1gf/cm ² ) In the loaded state, the thickness in this state was measured using a laser displacement meter, and was set as the thickness of the 2 nd member.

In the case where the object to be measured is a sanitary nonwoven fabric having a multilayer structure, q obtained by the measurement by the above-mentioned method is used _max The fiber layer on the side of the highest value of (2) was defined as the 1 st fiber layer, the fiber layer adjacent to the 1 st fiber layer was defined as the 2 nd fiber layer, and the 2 nd fiber layer was used for the above measurement.

Further, 9.8mN/cm in the entire sanitary article ² (1gf/cm ² ) The compression set under load is preferably 0.3mm or more, more preferably 0.4mm or more. The compression deformation amount of the entire sanitary product under such a load is preferably 15mm or less, and more preferably 10mm or less.

With this configuration, the nonwoven fabric can exhibit flexibility as a whole to improve the feeling of use, and the contact area between the first fiber aggregate 1 containing the fibers containing the polyethylene resin at least partially on the surface and the wearer can be increased to efficiently provide the wearer with a cool feeling.

The compression deformation amount can be easily achieved by, for example, a hot air method in which the temperature or the wind speed of hot air is set lower than a condition generally used, or by increasing the number of fibers or using fibers containing a resin having a melting point higher than the temperature of hot air, thereby reducing the fusibility between the fibers.

This can be easily achieved by adopting a configuration such that 2 or more fiber layers are provided and only 1 fiber layer is provided with a layer having a higher compression deformation amount than the other fiber layers, in addition to or instead of the above configuration; or the weight per unit area of 1 fiber layer is increased compared with other fiber layers; or blending the fibers with high melting point in 1 fiber layer.

The compression set can be measured, for example, using a KES-FB-3 compression tester manufactured by Kyoritsu Co. A cut piece of a predetermined size was cut out from a sanitary nonwoven fabric to be measured, and this was used as a sample. The sample was mounted on a test stand of a testing machine and placed with an area of 2cm ² The steel plates of the circular plane are compressed. The compression speed was 0.02mm/sec and the maximum compression load was 9.8mN/cm ² (1gf/cm ² ). The thickness under no load condition was defined as T0 (mm), and 9.8mN/cm was set ² (1gf/cm ² ) When the thickness under load is taken as the thickness Tm (mm), the compressive deformation amount (mm) can be calculated as "T0-Tm" obtained by subtracting the thickness Tm from the thickness T0.

When the 2 nd member is an absorbent sheet, the total weight per unit area is preferably 40g/m ² Above, more preferably 60g/m ² Above, more preferably 70g/m ² The above is preferably 500g/m ² Hereinafter, it is more preferably 400g/m ² Hereinafter, it is more preferably 300g/m ² The following.

When the 2 nd member is an absorbent body, the total weight per unit area is preferably 30g/m ² Above, more preferably 40g/m ² Above, more preferably 50g/m ² The above is preferably 600g/m ² Hereinafter, 550g/m is more preferable ² Hereinafter, it is more preferably 500g/m ² The following.

In the above description, the sanitary nonwoven fabric of the present invention and sanitary products (including absorbent articles) including the same are described, and a preferred method for producing the sanitary nonwoven fabric of the present invention will be described below. The production method comprises a step (hot air step) of obtaining a fiber aggregate by subjecting a web, at least a part of the surface of which is composed of fibers of a polyethylene resin, to hot air treatment.

In addition to this, a step of compacting the obtained fiber aggregate (compacting step) is preferably employed.

The thermal conductivity of the fiber used in the present production method is preferably within the above range.

First, a web of fibers comprising a polyethylene resin is formed for at least a portion of the surface. The web can be formed by, for example, a carding method using a known carding machine.

Then, a hot air treatment of blowing hot air to the web is performed to obtain an aggregate of fibers containing a polyethylene resin at least partially on the surface. This step is a step of forming a web of fibers into a nonwoven fabric, and the fiber aggregate produced in this manner is generally called a through-air nonwoven fabric.

In general, when a fiber web containing a polyethylene resin is subjected to hot air processing, from the viewpoint of production efficiency, core-sheath fibers having a polyethylene resin as a sheath and a high-melting resin other than the polyethylene resin as a core are mainly used, and it is extremely difficult to form a fiber nonwoven fabric containing only the polyethylene resin by hot air processing. In addition, the use of core-sheath fibers is advantageous in improving the texture and strength of the obtained hot-air nonwoven fabric, but there is still room for improvement in improving the thermal conductivity to make the user feel cool.

The present inventors have made diligent studies on these points of improvement and, as a result, have found that: by controlling the temperature and the wind speed of the hot wind in the hot wind step, a hot wind nonwoven fabric having good texture and strength can be efficiently produced even when fibers containing only a polyethylene resin are used.

The hot air to be blown to the fiber web in the hot air process preferably has a temperature and a wind speed within specific ranges. More specifically, from the viewpoint of improving the texture of the sanitary nonwoven fabric obtained, the temperature of the hot air blown to the fiber web may be preferably in the range of melting point M +4 ℃ or lower, more preferably in the range of melting point M +3 ℃ or lower, and still more preferably in the range of melting point M +2 ℃ or lower, in terms of the relationship with the melting point M (° c) of the resin contained in the fiber surfaces constituting the fiber web.

In addition, from the viewpoint of appropriately fusing the fibers constituting the web to each other so that the sanitary nonwoven fabric exhibits durable strength, the temperature of the hot air blown to the web may be preferably in the range of melting point M-4 ℃ or higher, more preferably in the range of melting point M-2 ℃ or higher, and still more preferably in the range of melting point M or higher.

The temperature of the hot air is the temperature of the hot air at the air outlet. The temperature can be measured, for example, by attaching a thermocouple to the outlet or a position at the limit of the proximity to the outlet.

For example, when fibers having HDPE (melting point M:130 ℃) on the surface thereof are used as the fibers constituting the web, the temperature of the hot air may be preferably 126 ℃ or higher, more preferably 128 ℃ or higher, and still more preferably 130 ℃ or higher.

The temperature of the hot air under the above conditions may be preferably 134 ℃ or lower, more preferably 133 ℃ or lower, and still more preferably 132 ℃ or lower.

The melting point M of the resin constituting the fiber surface can be measured by a differential scanning calorimeter (DSC 7000x manufactured by Hitachi High-Tech Science Co., ltd.). First, using a fiber sample (1 mg) cut into small pieces, thermal analysis of the sample was performed at a temperature rise rate of 10 ℃/min, and the melting peak temperature of each resin was measured. The melting point is defined as the melting peak temperature at the first temperature increase. In the case where a clear melting point cannot be measured by this method, this resin is defined as "a resin having no melting point". In the case of a resin having no melting point, the softening point is defined as melting point M.

In the hot air step, the air velocity of the hot air blown to the fiber web is preferably 0.6 m/sec or more, and more preferably 1 m/sec or more, from the viewpoint of sufficiently passing the hot air in the thickness direction of the fiber web to easily fuse the fibers.

From the same viewpoint, the wind speed of the hot air blown to the fiber web is preferably 2 m/sec or less, and more preferably 1.4 m/sec or less.

By performing the hot air process under the conditions of the temperature and the air velocity, the polyethylene resin present on the surface of the fibers constituting the fiber web can be melted or softened, and the portions where the fibers are fused with each other can be randomly formed, so that the produced sanitary nonwoven fabric exhibits flexibility and good texture due to the hot air nonwoven fabric, and also exhibits durable strength.

The web conveyance speed in the hot air step is preferably 3m/min or more, more preferably 10m/min or more, and preferably 200m/min or less, and more preferably 160m/min or less within the above temperature and wind speed ranges.

The fiber aggregate obtained through the above steps is formed into a nonwoven fabric, and thus can be used as it is as the sanitary nonwoven fabric of the present invention. The sanitary non-woven fabric is a hot air non-woven fabric.

From the viewpoint of easily obtaining a sanitary nonwoven fabric having a predetermined volume filling ratio, it is preferable to further perform a compacting treatment (compacting step) on the fiber aggregate obtained through the above-described steps. The compacting treatment in this step may be a method capable of compressing the fiber aggregate by applying pressure in the thickness direction thereof.

The compacting treatment can be performed, for example, by a method in which the fiber aggregate is placed between two metal flat plates and pressed (hereinafter, this method is also referred to as "pressing method"), or a method in which the fiber aggregate is introduced between a pair of rolls and pressed (hereinafter, this method is also referred to as "calendering method").

The compacting treatment may be performed only once, or may be performed a plurality of times by the same or different methods as required. The temperature in the compacting treatment may be room temperature, may be in a heated state, or may be a combination of these.

The conditions for the densification treatment are preferably under pressure in a heated state. More specifically, in the case of using the compacting method, the pressurizing condition in the compacting treatment is preferably 5MPa or more, and more preferably 10MPa or more, in terms of surface pressure, from the viewpoint of sufficiently compacting the fiber aggregate and easily obtaining a sanitary nonwoven fabric having a high volume filling rate.

In addition, in the case of using the pressing method, the pressing condition in the compacting treatment is preferably 72MPa or less, and more preferably 32MPa or less, in terms of surface pressure, from the viewpoint of not making the fiber aggregate into a film, maintaining the fiber shape in which the boundary between the constituent fibers is clear, and improving the texture of the obtained sanitary nonwoven fabric.

In addition, from the viewpoint of sufficiently densifying the fiber aggregate to easily obtain a sanitary nonwoven fabric having a high volume filling rate, the pressure condition in the calendering is preferably 78.4N/cm (8 kgf/cm) or more, and more preferably 127.4N/cm (13 kgf/cm) or more, as represented by a line pressure.

In addition, from the viewpoint of not forming a film of the fiber aggregate, maintaining a fiber shape in which the boundaries between the constituent fibers are clear, and improving the texture of the obtained sanitary nonwoven fabric, the pressing condition in the calendering method is preferably 686N/cm (70 kgf/cm) or less, and more preferably 294N/cm (30 kgf/cm) or less, as represented by a line pressure.

In both of the pressing method and the calendering method, the heating temperature in the compacting treatment is preferably 70 ℃ or higher, and more preferably 80 ℃ or higher, from the viewpoint of sufficiently compacting the fiber aggregate and easily obtaining a sanitary nonwoven fabric having a high volume filling factor.

In the case of either the pressing method or the calendering method, the heating temperature in the compacting treatment is preferably 120 ℃ or lower, more preferably 110 ℃ or lower, from the viewpoint of not making the fiber aggregate into a film, maintaining the fiber shape in which the boundary between the constituent fibers is clear, and improving the texture of the obtained sanitary nonwoven fabric.

In the case of heating in the compacting treatment, the flat metal plate may be heated to the above temperature range in the case of the pressing method, and the peripheral surface of the roll may be heated to the above temperature range in the case of the calendering method.

The pressing time in the compacting treatment may be appropriately set as long as the conditions are such that the fiber shape of the fibers constituting the fiber aggregate can be maintained and compacting can be performed.

For example, in the case of using the pressing method, the pressing time under the above-described pressure and temperature conditions may be preferably 5 seconds or more, and more preferably 10 seconds or more per one compacting treatment.

In the case of using the pressing method, the pressing time under the above-described pressure and temperature conditions may be preferably 25 seconds or less, and more preferably 20 seconds or less, per one compacting treatment.

For example, in the case of using the calendering method, the pressing time under the above-described pressure and temperature conditions may be preferably 0.01 seconds or more, and more preferably 0.04 seconds or more per compacting treatment.

In the case of using the calendering method, the pressing time under the above-described pressure and temperature conditions may be preferably 0.1 seconds or less, and more preferably 0.08 seconds or less per densification treatment.

By performing the compacting treatment under the above conditions, the fiber assembly can be compressed in the thickness direction, and a sanitary nonwoven fabric having a predetermined volume filling rate can be easily obtained.

In particular, since the resin constituting the fibers is in a state of being hardly melted in the above pressure and temperature ranges and the form stability and dimensional stability by the heat treatment can be improved, the sanitary nonwoven fabric maintaining a predetermined volume filling rate even after the production can be obtained.

In addition, when fibers having a circular cross-sectional shape are used, the cross-sectional shape of the fibers can be flattened by the compacting treatment, and therefore, there is also an advantage that the volume filling ratio can be increased.

The sanitary nonwoven fabric obtained by the above method is a hot air nonwoven fabric even when it is subjected to a compacting treatment.

The sanitary nonwoven fabric of the present invention may be produced by a method based on a spunbond method instead of the above production method. The hygiene nonwoven produced in this way is a spunbond nonwoven.

More specifically, a raw material resin for fibers is extruded from a spinneret having a plurality of fine holes in a molten state, the extruded resin is stretched by a roller or the like to form long fibers, and the long fibers are gathered on a mesh-like conveyor belt to obtain a mesh having at least a part of the surface of the mesh containing fibers of a polyethylene resin. Thereafter, the web is introduced between embossing rollers and densified (thermocompression bonding) by heating and pressing, thereby obtaining the nonwoven fabric for hygiene of the present invention. That is, the method is one in which the nonwoven fabric and the densification of the fiber web are performed simultaneously. The temperature and the pressing condition of the embossing roll can be set in the same ranges as those of the above-described densifying treatment.

In the case of producing a nonwoven fabric having a multilayer structure, for example, a 2 nd web containing a thermoplastic resin formed by a carding method is laminated on a web containing a polyethylene resin at least at a part of the surface thereof to form a laminate of webs. Then, the laminate is subjected to hot air treatment, whereby a hot air nonwoven fabric as a fiber aggregate having a multilayer structure can be obtained. In this case, the temperature of the hot air to be blown is preferably determined by setting the melting point of the resin having the lowest melting point as the melting point M.

As another mode of producing a nonwoven fabric for sanitary use having a multilayer structure, it can be obtained by subjecting a fiber web containing a polyethylene resin at least a part of the surface thereof and a 2 nd fiber web containing a thermoplastic resin to hot air treatment to obtain fiber sheets, respectively, and then joining these fiber sheets with an adhesive interposed therebetween.

The fiber aggregate obtained through the above-described steps can be used as it is as the sanitary nonwoven fabric of the present invention. In addition, the compacting step may be performed under the above conditions.

Alternatively, the target nonwoven fabric may also be manufactured by a method based on a spunbond method. As a production method, for example, the 2 nd fiber web may be laminated on a fiber web containing a polyethylene resin at least at a part of the surface thereof, and densified (thermocompression bonding) by heating and pressing in this state. The hygiene nonwoven produced in this way is a spunbond nonwoven.

Through the above steps, the sanitary nonwoven fabric of the present invention can be obtained. The sanitary nonwoven fabric is preferably incorporated as a component of a sanitary product such as an absorbent article in a subsequent step.

When the sanitary nonwoven fabric is used as a constituent material of a sanitary product such as an absorbent article, the sanitary product can be produced by one or more of the following steps in any step of producing the sanitary product: a step of cutting the sanitary nonwoven fabric produced by the above method, using the sanitary nonwoven fabric as one of the constituent materials; the sanitary nonwoven fabric is subjected to various operations such as laminating or bonding with other constituent materials (for example, an absorbent body, a sheet, etc.) constituting the sanitary product.

In the case of manufacturing a sanitary product provided with the 2 nd member, for example, after separately manufacturing the sanitary nonwoven fabric, the sanitary nonwoven fabric as the 1 st fiber assembly and the absorbent body or the absorbent sheet as the 2 nd member may be laminated or joined in an adjacent state at any stage of the manufacturing process of the sanitary product. In this case, the sanitary nonwoven fabric may be disposed so as to constitute a surface facing the skin of the wearer when the sanitary product is worn, or may be disposed on a surface side not facing the skin of the wearer when the sanitary product is worn.

The present invention has been described above based on preferred embodiments of the present invention, but the present invention is not limited to the above embodiments.

The embodiments of the present invention described above also disclose the following nonwoven fabric for hygiene, absorbent article provided with the same, and method for producing nonwoven fabric for hygiene.

＜1＞

A sanitary nonwoven fabric comprising fibers at least a part of the surface of which comprises a polyethylene resin and

the volume filling rate is 3.5% or more, more preferably 7% or more, still more preferably 10% or more, and still more preferably 14% or more.

＜2＞

A sanitary nonwoven fabric comprising fibers having a thermal conductivity of 0.11W/mK or more, more preferably 0.13W/mK or more, and still more preferably 0.15W/mK or more on at least a part of the surface thereof, and

the volume filling rate is 3.5% or more, more preferably 7% or more, and still more preferably 14% or more.

＜3＞

The nonwoven fabric for sanitary use according to the above < 1 > or < 2 >, wherein the volume filling rate is 60% or less, preferably 50% or less, and more preferably 30% or more.

＜4＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 3 >, wherein the fibers are (i) bicomponent composite fibers in which the outer surface and the inner portion of the fibers contain a polyethylene resin, or (ii) bicomponent composite fibers in which a low-melting-point component containing a polyethylene resin and a high-melting-point component having a high melting-point and low-melting-point component are contained, and the low-melting-point component is continuously present on at least a part of the fiber surface in the longitudinal direction.

＜5＞

The sanitary nonwoven fabric according to any one of the above-mentioned < 1 > to < 4 >, wherein the content of the polyethylene resin is 70% by mass or more and 100% by mass or less, preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 100% by mass or less, based on the total mass of the resins contained in the sanitary nonwoven fabric.

＜6＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 5 >, wherein the resin constituting the fibers is only a polyethylene resin.

＜7＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 6 >, wherein the fibers have a cross-sectional shape having a major axis and a minor axis, and

the ratio of the major axis length to the minor axis length (major axis length/minor axis length) is 1.5 or more and 10 or less.

＜8＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 7 >, wherein the fibers are in contact with each other at a plurality of points in a cross-sectional view.

＜9＞

The sanitary nonwoven fabric according to any one of the above < 1 > to < 8 >, having 4.9mN/cm ² The thickness under load is 0.1mm to 3 mm.

＜10＞

The sanitary nonwoven fabric according to any one of the above < 1 > to < 9 >, having 4.9mN/cm ² The thickness under load is 0.3mm to 0.5 mm.

＜11＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 10 >, having a basis weight of 15g/m ² Above and 140g/m ² The following.

＜12＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 11 >, having a basis weight of 25g/m ² Above and 50g/m ² The following.

＜13＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 12 >, wherein the polyethylene resin contains a high-density polyethylene resin, preferably contains only a high-density polyethylene resin.

＜14＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 13 >, wherein the fiber diameter of the fibers is 3 μm or more, preferably 5 μm or more.

＜15＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 14 >, wherein the fiber diameter of the fibers is 70 μm or less, preferably 50 μm or less.

＜16＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 15 > which is a hot air nonwoven fabric.

＜17＞

A sanitary article comprising the sanitary nonwoven fabric according to any one of the above items < 1 > to < 16 >.

＜18＞

The sanitary product according to the above < 17 >, wherein the sanitary nonwoven fabric constitutes a surface of the sanitary product facing the skin of the user.

＜19＞

A sanitary product according to the above-mentioned < 17 > or < 18 >, which is an absorbent article.

＜20＞

The sanitary product according to any one of the above items < 17 > to < 19 >, wherein the sanitary nonwoven fabric is disposed on an outer surface of the sanitary product.

＜21＞

The sanitary nonwoven fabric or sanitary article according to any one of the above-mentioned items < 1 > to < 20 >, which is disposable.

＜22＞

A method for producing a sanitary nonwoven fabric, comprising subjecting a web comprising fibers of a polyethylene resin at least partially on the surface thereof to hot air treatment to obtain a fiber aggregate, and thereafter,

the fiber aggregate is subjected to a compacting treatment.

＜23＞

The process according to < 22 >, wherein the densification treatment is performed under a surface pressure of 5MPa or more, preferably 10MPa or more, or under a linear pressure of 78.4N/cm (8 kgf/cm) or more, preferably 127.4N/cm (13 kgf/cm) or more, and the densification treatment is performed under a linear pressure of 13kgf/cm or more

At a temperature of 70 ℃ to 120 ℃.

＜24＞

The method of producing a sanitary nonwoven fabric according to the above < 22 > or < 23 >, wherein the densification treatment is performed under a surface pressure of 30MPa or less, preferably 20MPa or less, or under a linear pressure of 686N/cm (70 kgf/cm) or less, preferably 294N/cm (30 kgf/cm) or less.

＜25＞

The method for producing a sanitary nonwoven fabric according to any one of the above < 22 > to < 24 >, wherein the compacting treatment is performed at a temperature of 80 ℃ or higher and 110 ℃ or lower.

＜26＞

The method for producing a sanitary nonwoven fabric according to any one of the above items < 22 > to < 25 >, wherein the hot air treatment is performed by blowing hot air having a temperature of-4 ℃ or higher of the melting point of the resin constituting the fiber surface and +4 ℃ or lower of the melting point of the resin to the web at an air speed of 0.6 m/sec or higher and 2 m/sec or lower.

＜27＞

The method for producing a sanitary nonwoven fabric according to any one of the above items < 22 > to < 26 >, wherein the hot air treatment is more preferably performed by blowing hot air having a temperature of-2 ℃ or higher and +2 ℃ or lower to the web, the melting point of the resin constituting the fiber surface.

＜28＞

The method for producing a sanitary nonwoven fabric according to any one of the above items < 22 > to < 27 >, wherein the surface of the fiber contains a high-density polyethylene resin,

the melting point of the high-density polyethylene resin is 130 ℃, and

the hot air treatment is performed by blowing hot air having a temperature of 126 ℃ or higher, preferably 128 ℃ or higher, and more preferably 130 ℃ or higher to the web.

＜29＞

The method for producing a sanitary nonwoven fabric according to any one of the above items < 22 > to < 28 >, wherein the surface of the fiber contains a high-density polyethylene resin,

the melting point of the high-density polyethylene resin is 130 ℃, and

the hot air treatment is performed by blowing hot air having a temperature of 134 ℃ or less, preferably 133 ℃ or less, and more preferably 132 ℃ or less to the web.

＜30＞

The method for producing a sanitary nonwoven fabric according to any one of the above items < 22 > to < 29 >, wherein the hot air treatment is performed by blowing hot air to the web at an air speed of 1 m/sec or more and 1.4 m/sec or less.

＜31＞

A method for manufacturing a sanitary product, comprising one or more of the following steps in any step of manufacturing the sanitary product: a step of cutting a sanitary nonwoven fabric produced by the method of producing a sanitary nonwoven fabric described in any one of the above-mentioned < 22 > to < 30 > as one of the constituent materials; and a step of laminating or bonding the sanitary nonwoven fabric and another constituent material constituting the sanitary product.

＜32＞

The sanitary nonwoven fabric according to any one of the above-mentioned items < 1 > to < 16 > having a cool feeling q when exposed to a touch _max Is 0.06W/m ² As described above.

＜33＞

The sanitary nonwoven fabric according to any one of the above items < 1 > to < 16 > and < 32 >, wherein the proportion of the constituent fibers present on the surface of the sanitary nonwoven fabric is 40% or more by area.

＜34＞

The nonwoven fabric for sanitary use according to any one of the above-mentioned < 1 > to < 16 >, < 32 >, < 33 >, wherein the volume filling rate is 10.0% or more.

＜35＞

A sanitary article comprising the sanitary nonwoven fabric described in any one of the above items < 1 > to < 16 > and < 32 > to < 34 > and the 2 nd member disposed adjacent to the nonwoven fabric, wherein the sanitary nonwoven fabric is used as a sanitary article

The above component 2 was 9.8mN/cm ² (1gf/cm ² ) The amount of compression set under load is 0.3mm or more.

＜36＞

The sanitary product according to < 35 > above, wherein the 2 nd member is a fiber aggregate different from the sanitary nonwoven fabric.

＜37＞

The sanitary product according to the above < 36 >, wherein the 2 nd member is an absorbent body.

＜38＞

A method for producing a sanitary nonwoven fabric, which comprises the steps of producing the sanitary nonwoven fabric as described in any one of the above items < 1 > to < 16 >, < 32 > to < 34 > and

subjecting a web comprising fibers of a polyethylene resin at least partially on the surface to a hot air treatment to obtain a fiber aggregate, and then,

the fiber aggregate is subjected to a compacting treatment.

Examples

The present invention will be described in more detail below with reference to examples. The scope of the invention is not limited to this example.

[ examples 1 to 5]

A fiber including a single resin HDPE and having a flat, multi-lobal cross-sectional shape with a major axis and a minor axis (hereinafter, this shape is also referred to as "flat profile" as in the table) was used. The major axis length, the minor axis length, and the ratio of the major axis length to the minor axis length in the fiber cross section (this ratio is also referred to as "major axis/minor axis ratio" in the table) are shown in table 1 below.

First, a web of the fibers whose basis weight was adjusted as shown in table 1 below was subjected to hot air treatment to obtain a nonwoven fiber assembly. The conditions of the hot air treatment are shown in table 1 below. Then, the fiber assembly was subjected to densification treatment under the conditions of heating and pressurization shown in table 1 below by a pressing method, to obtain the objective sanitary nonwoven fabric. The obtained nonwoven fabric is a single layer.

[ examples 6 to 8]

The same procedures as in examples 1 to 5 were carried out except that the basis weight was adjusted as shown in table 1 below, and the densification treatment was carried out by calendering under the heating and pressurizing conditions shown in table 1 below, to obtain the objective nonwoven fabrics for hygiene. The obtained nonwoven fabric is a single layer.

[ example 9]

A core-sheath fiber (hereinafter, also referred to as PET/HDPE fiber) having a core of PET and a sheath (fiber surface) of HDPE and having a perfect circular cross-sectional shape was used. The polyethylene resin content of the fiber was 50 mass%. The fiber web containing the fibers was subjected to hot air treatment and densification treatment under the same conditions as in example 1, to obtain a target sanitary nonwoven fabric. The obtained nonwoven fabric is a single layer.

[ example 10]

A fiber comprising a single resin HDPE and having a right circular cross-sectional shape is used. A web of the above fibers whose basis weight was adjusted as shown in table 1 below was produced by a spunbond process, and the web was densified by an embossing roll to obtain a sanitary nonwoven fabric composed of a spunbond nonwoven fabric. The conditions for the spunbond process are shown in table 1 below. The obtained nonwoven fabric is a single layer.

[ example 11]

The objective nonwoven fabric for hygiene was obtained in the same manner as in example 1, except that the densification treatment was not performed.

[ examples 12 to 14]

A core-sheath fiber (hereinafter, also referred to as PP/HDPE fiber) having a core of PP and a sheath (fiber surface) of HDPE and a perfect circular cross-sectional shape is used. The polyethylene resin content of the fiber was 50 mass%. A web of the fibers whose basis weight was adjusted as shown in table 1 below was formed, and the web was subjected to hot air treatment and compacting treatment under the same conditions as in example 1 to obtain the objective sanitary nonwoven fabric. The obtained nonwoven fabric is a single layer.

Comparative example 1

A web of fibers was formed using the same core-sheath fibers as in example 9, and subjected to hot air treatment under the conditions shown in table 1 below to obtain the objective nonwoven fabric for hygiene. In this comparative example, no densification treatment was performed.

Comparative example 2

A web of fibers was formed using the same core-sheath fibers as in example 12, and subjected to hot air treatment under the conditions shown in table 1 below to obtain the objective nonwoven fabric for hygiene. In this comparative example, no densification treatment was performed.

Comparative example 3

A web of fibers was formed using the same core-sheath fibers as in example 12, and subjected to hot air treatment under the conditions shown in table 1 below, and then subjected to densification treatment by calendering without heating under the conditions shown in table 1 below, to obtain the objective sanitary nonwoven fabric.

[ measurement of thickness of sanitary nonwoven Fabric ]

The thickness of the sanitary nonwoven fabrics of examples and comparative examples was measured. In the measurement of the thickness, 4.9mN/cm was applied to the sanitary nonwoven fabric as the object of the measurement ² Under a load, measurement was performed at 5 or more positions using a laser displacement gauge, and the arithmetic mean of the obtained measurement values was defined as the thickness (mm). The results are shown in Table 1.

[ measurement of thermal conductivity of nonwoven Fabric ]

The sanitary nonwoven fabrics of examples and comparative examples were measured for thermal conductivity by the following method.

(1. Sample preparation)

A sanitary nonwoven fabric to be measured was cut into small pieces, and a laminate of about 10g of a plurality of pieces stacked was held between 2 SUS plates and positioned at the center of the SUS plates, and heated for 1 minute without applying pressure to obtain a melt. The heating temperature is the melting point M +20 ℃ as measured by the differential scanning calorimeter, and in the case of a nonwoven fabric containing a plurality of resin materials, the heating is carried out based on the melting point of the resin having the highest melting point. Specifically, the nonwoven fabric containing pure HDPE fibers was heated at 50 ℃, the nonwoven fabric containing PP/HDPE fibers was heated at 180 ℃, and the nonwoven fabric containing PET/HDPE fibers was heated at 300 ℃.

Then, a gauge pressure of 200kgf (total mass including the top plate: 21848kg; in the case of calculating the pressure by the surface pressure, since the area of the melt changes with the melting of the resin, the surface pressure is calculated based on the area of the finally obtained circular resin plate, for example, in the case of a circular resin plate having a diameter of 15cm, the surface pressure is 12 MPa) is maintained for 1 minute, and then the pressure is maintained in a pressurized state and water-cooled to 20 ℃ to obtain a circular resin plate having a diameter of about 15 to 20cm (the diameter of the obtained circular resin plate may change depending on the melt viscosity of the resin).

Then, the obtained circular resin plate is cut in a radial line shape passing through the center, and if the maximum diameter length is 5cm or more, the circular resin plate is further cut to 5cm or less. Then, the cut resin plates were superposed on each other so that the extending direction of the virtual line segment having the largest diameter was random to eliminate the influence of the resin orientation, and then 2 shims having a thickness of 1mm were disposed in parallel at a position 10cm from the center of the SUS plate, and the SUS plate was superposed thereon. Thereafter, heating under non-pressurized conditions and heating and cooling under pressurized conditions were performed in the same manner as described above. When air bubbles enter, the same operation is repeated. The purpose of the 2-time heating and melting was to melt the sample temporarily, to eliminate the influence of crystallization of the resin which changed during the fiber spinning process, and to make the thermal history constant. Thereby, a film was obtained.

(2. Measurement of thermal conductivity)

The thermal conductivity was measured by the following method using a measuring apparatus (KES-F7 Thermo Lab II manufactured by Kyoto technologies Co., ltd.).

First, a circle having a diameter of 17cm was cut out from the obtained film, and the film was left to stand at room temperature of 23 ℃ and a relative humidity of 50% for 24 hours. Then, the thermal conductivity of the object to be measured is measured by the measuring device in accordance with the measurement guidelines of the device. Specifically, the temperature of a heat source for measurement (BT-BOX, which is formed by integrating an aluminum plate 5cm in length by 5cm in width and 1mm in thickness with a heater, etc.) was set to 33 ℃ (10 ℃ higher than the surface temperature of the object to be measured), and the contact area was reduced for every 0.25m of the film in order to prevent the film from warping ² The heat source body was brought into contact with the film so as to apply a load of 1kg to the area of (3). In the display panel of the measuring instrument, the time when the heat flow from the heat source body to the measurement target becomes constant is set as the measurement start time, and the average heat flow within 60 seconds from this time is measured. According to the determinationThe conditions and the measured heat flow rate were calculated based on the following formula (I). The thickness D of the film is an arithmetic average of thicknesses measured at 3 or more positions by a laser displacement meter under no load. The above measurement was performed 3 times for each measurement object, and the maximum value among the obtained measurement values was defined as the thermal conductivity (W/mK) of the sample. The results are shown in Table 1.

As reference examples, the thickness D and the thermal conductivity were measured for each of the films produced by the above-described method using only PET and the films produced by the above-described method using only PP. The results are shown in table 2 together with the results of examples and comparative examples.

k＝100×(W×D)/(A×ΔT)…(I)

(k: thermal conductivity [ W/mK ]]W is as follows: heat flow rate [ W/m ] ² ]D, D: thickness of film [ cm ]]And A: aluminum plate area (25 cm) ² ) Δ T: temperature difference between Heat Source and film (10 ℃ C.)

[ measurement of volume filling Rate ]

The volume filling ratio (%) of the sanitary nonwoven fabrics of examples and comparative examples was calculated by the above method. The results are shown in Table 1.

[ Cool feeling upon contact q _max Measurement of (2)]

The method comprises storing heat in a heat plate such as a metal plate with a temperature sensor, setting the temperature of the heat plate to be higher than that of a measurement object, contacting the heat plate with the surface of the measurement object, immediately transferring the heat stored in the heat plate to the measurement object at a low temperature side after the contact, wherein the maximum value of the heat flow is the contact cooling feeling q _max 。

Cool feeling of contact q _max The measurement of (2) was carried out by the following method using a measuring apparatus (KES-F7 Thermo Lab II manufactured by Kyoto technologies Co., ltd.).

First, a test piece was cut out from a sanitary nonwoven fabric to be measured in a size of 10cm in length × 10cm in width, and the test piece was left to stand at room temperature of 23 ℃ under an atmosphere of 50% relative humidity for 24 hours.

Then, in this environment, the test piece was placed on the measurement stand, and the test piece was fixed to the measurement stand using a double-sided adhesive tape. A thermostat using gas or liquid as a heat medium is used as the measurement stage.

Then, the measurement device is used to measure the cool feeling q of the object to be measured according to the measurement guidance of the device _max And (4) carrying out measurement. Specifically, the usable area is 9.0cm ² And a pure copper plate having a mass of 9.8g as a hot plate to be brought into contact with the measurement object, the initial temperature of the copper plate was set to 33 ℃ (10 ℃ higher than the surface temperature of the measurement object), the contact pressure of the copper plate and the measurement object was set to 1kPa, the copper plate was brought into contact with the test piece, the value of the heat flow rate at the moment of contact was set to zero, and the maximum value of the heat flow rate was measured. The measurement is performed 5 times for each surface to be measured, and the arithmetic average of the obtained measured values is defined as the cool feeling q of contact of the object to be measured _max (W/m ² )。

Cool feeling of contact q _max The larger the value of (A), the faster the heat transfer, and the more easily the user feels cool. The results are shown in table 1 below.

[ Table 1]

[ Table 2]

As shown in tables 1 and 2, the sanitary nonwoven fabrics of the examples have higher thermal conductivity and volume filling ratio than the comparative examples, and have cool feeling q _max And is also high.

In particular, as is clear from examples 1 to 8, the effect is remarkable by using the flat and shaped fibers.

Therefore, the sanitary non-woven fabric of the present invention can give a cool feeling when it is in contact with the skin of a user, thereby giving a comfortable feeling of use.

[ examples 15 and 16]

The hot-air nonwoven fabric containing HDPE, which is a single resin used in example 2, was used as the 1 st fiber layer, and the single-layer hot-air nonwoven fabric containing PET/HDPE fibers, which was adjusted to have the basis weight as shown in table 3 below, was used as the 2 nd fiber layer. These fiber layers were laminated and bonded with an adhesive to obtain a sanitary nonwoven fabric comprising a fiber sheet having a plurality of fiber layers (2 layers). The structure of the 1 st fiber layer in this example was the same as the sanitary nonwoven fabric of example 2.

[ examples 17 to 21]

The hot-air nonwoven fabric containing HDPE, which is a single resin used in example 4, was used as the 1 st fiber layer, and the single-layer hot-air nonwoven fabric containing PET/HDPE fibers, which was adjusted to have the basis weight as shown in table 3 below, was used as the 2 nd fiber layer. These fiber layers were laminated and bonded with an adhesive to obtain a sanitary nonwoven fabric comprising a fiber sheet having a plurality of fiber layers (2 layers). The structure of the 1 st fiber layer in this example is the same as that of the sanitary nonwoven fabric of example 4.

[ example 22]

The hot-air nonwoven fabric containing HDPE, which is a single resin used in example 10, was used as the 1 st fiber layer, and the single-layer hot-air nonwoven fabric containing PET/HDPE fibers, which was adjusted to have the basis weight as shown in table 3 below, was used as the 2 nd fiber layer. These fiber layers were laminated and bonded with an adhesive to obtain a sanitary nonwoven fabric composed of a fiber sheet having a plurality of fiber layers (2 layers). The structure of the 1 st fiber layer in this example was the same as the sanitary nonwoven fabric of example 10.

[ measurement of volume filling Rate ]

The volume filling (%) of the sanitary nonwoven fabric of the example was calculated in the same manner as described above. The results are shown in table 3 below. In table 3, the results of only the sanitary nonwoven fabric in examples 2, 4 and 10 will be disclosed again.

[ Cool feeling upon contact q _max Measurement of (2)]

The cool feeling q of the sanitary nonwoven fabric of the example was measured in the same manner as the above method _max . In examples 15 to 22, the measurement was performed with respect to the surface on the side where the 1 st fiber layer was disposed. The results are shown in Table 3.

[ evaluation of functionality of Cool feeling ]

Please refer to 20 professional functional inspectors who touched the sanitary nonwoven fabrics of examples 2, 4 and 10 and the sanitary nonwoven fabrics of examples 15 to 22 on the side of the 1 st fiber layer, respectively, and evaluated the cool feeling felt when they touched the surface according to the following criteria. The sanitary nonwoven fabrics used for evaluation were those which were placed in an environment of 23 ℃ and became isothermal with the ambient temperature. The higher the arithmetic average value of the evaluation score, the more effectively the sanitary nonwoven fabric is perceived as cool. The results are shown in table 3 below.

And 5, dividing: and q is _max A fiber sheet having a thickness of 0.15 or more strongly feels cool to the same extent, and is very excellent in cool feeling.

And 4, dividing: can be used for making people feel cool.

And 3, dividing: can feel cool.

And 2, dividing: a cooling sensation was hardly felt.

1 minute: and q is _max The hot-air nonwoven fabric having a thickness of less than 0.06 is completely free from a cool feeling to the same extent.

[ Table 3]

As shown in Table 3, it was found that the sanitary nonwoven fabrics of the examples all had the volume filling ratio and the cool feeling q upon contact _max All are high, and people can feel excellent cool.

The fiber surface presence (%) of the sanitary nonwoven fabrics of example 9 and comparative example 1 was calculated by the above method.

As a result, the fiber surface presence ratio of example 9 was 58%, and the surface fiber presence ratio of comparative example 1 was 36%. Therefore, the fiber surface presence ratio in example 9 is higher than that in comparative example 1, and the contact property of the fiber with the object to be contacted can be further improved. As a result, a user can feel an excellent cool feeling.

Industrial applicability

According to the present invention, there are provided a sanitary nonwoven fabric which gives a comfortable feeling of use by giving a cool feeling when in contact with the skin, and a sanitary article and an absorbent article provided with the same.

Claims

1. A sanitary nonwoven fabric comprising fibers at least a part of the surface of which comprises a polyethylene resin and

the volume filling rate is more than 3.5%.

2. A sanitary nonwoven fabric comprising fibers having a thermal conductivity of 0.11W/mK or more in at least a part of the surface thereof

The volume filling rate is more than 3.5%.

3. The sanitary non-woven fabric according to claim 1 or 2, wherein the resin constituting the fibers is only a polyethylene resin.

4. The sanitary nonwoven fabric according to any one of claims 1 to 3, wherein the cross-sectional shape of the fibers has a major axis and a minor axis, and

the ratio of the major axis length to the minor axis length is 1.5 or more and 10 or less.

5. The sanitary non-woven fabric according to any one of claims 1 to 4, wherein the fibers are in multi-point contact with each other in a cross-sectional view.

6. The sanitary nonwoven fabric according to any one of claims 1 to 5, which has a mN/cm of 4.9 ² The thickness under load is 0.1mm to 3 mm.

7. The sanitary nonwoven fabric according to any one of claims 1 to 6, having a weight per unit area of 15g/m ² Above and 140g/m ² The following.

8. The sanitary nonwoven fabric according to any one of claims 1 to 7, which is cool to the touch q _max Is 0.06W/m ² The above.

9. The sanitary nonwoven fabric according to any one of claims 1 to 8, wherein the proportion of the constituent fibers present on the surface of the sanitary nonwoven fabric is 40% by area or more.

10. The sanitary nonwoven fabric according to any one of claims 1 to 9, wherein the volume filling rate is 10.0% or more.

11. The sanitary non-woven fabric according to any one of claims 1 to 10, wherein the fiber is a fiber containing a polyethylene resin on both the outer surface and the inner portion of the fiber, or

The fiber is a composite fiber containing a low-melting-point component containing a polyethylene resin and a high-melting-point component having a higher melting point than the low-melting-point component, and the low-melting-point component is continuously present on at least a part of the fiber surface in the longitudinal direction.

12. The sanitary nonwoven fabric according to any one of claims 1 to 11, wherein the fiber comprises a polyethylene resin, and

the content of the polyethylene resin is 70 to 100 mass% based on the total mass of the fibers.

13. The sanitary non-woven fabric according to any one of claims 1 to 12, wherein the fiber comprises only a polyethylene resin.

14. The sanitary non-woven fabric according to any one of claims 1 to 13, wherein the fiber comprises a high density polyethylene resin.

15. The sanitary non-woven fabric according to any one of claims 1 to 14, wherein the fiber contains only a high-density polyethylene resin.

16. The sanitary nonwoven fabric according to any one of claims 1 to 15, wherein the fiber diameter of the fiber is 3 μm or more and 70 μm or less.

17. A sanitary article comprising the sanitary nonwoven fabric according to any one of claims 1 to 16 and a 2 nd member disposed adjacent to the nonwoven fabric, the sanitary nonwoven fabric being

The 2 nd component is 9.8mN/cm ² The amount of compression set under load is 0.3mm or more.

18. The sanitary product according to claim 17, wherein the 2 nd member is a fiber aggregate different from the sanitary nonwoven fabric.

19. The sanitary article according to claim 17, wherein the 2 nd member is an absorbent body.

20. The sanitary article according to any one of claims 17 to 19, which is an absorbent article.

21. The sanitary product according to any one of claims 17 to 20, wherein the sanitary nonwoven fabric is disposed on an outer surface.

22. An absorbent article comprising the sanitary nonwoven fabric according to any one of claims 1 to 16.

23. A method for producing the sanitary nonwoven fabric according to any one of claims 1 to 16, the method comprising

and compacting the fiber assembly.

24. The production method according to claim 23, wherein the compacting treatment is performed at a surface pressure of 5MPa or more or a linear pressure of 78.4N/cm or more and at a temperature of 70 ℃ or more and 120 ℃ or less.

25. The production method according to claim 23 or 24, wherein the hot air treatment is performed by blowing hot air having a temperature of-4 ℃ or higher of a melting point of the resin constituting the fiber surface and +4 ℃ or lower of the melting point of the resin to the web at an air speed of 0.6 m/sec or higher and 2 m/sec or lower.