Sanitary nonwoven fabric, sanitary article and absorbent article having the same, and method for producing sanitary nonwoven fabric

Abstract

The sanitary nonwoven fabric contains fibers containing polyethylene resin on at least a portion of its surface, and the volume filling rate is 3.5% or more. It is also preferred that the fibers have 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. It is also preferred that the fibers are in contact with each other at multiple points in a cross-sectional view of the nonwoven fabric. In addition, the present invention also provides an absorbent article having the sanitary nonwoven fabric. Furthermore, the present invention also provides a method for manufacturing a sanitary nonwoven fabric, wherein a web of fibers containing polyethylene resin on at least a portion of its surface is subjected to hot air treatment and compaction treatment.

Description

Technical Field

[0001] The present invention relates to a sanitary nonwoven fabric, a sanitary product and an absorbent article having the same, and a method for producing the sanitary nonwoven fabric. Background Art

[0002] The industry has proposed fiber sheets that can make people feel cool and articles with the fiber sheets. For example, Patent Document 1 discloses a comfortable fabric used in clothing for eliminating the feeling of summer heat. According to the document, the fabric contains at least one organic polymer fiber with a thermal conductivity of 5 W / mK or more in the fiber axial direction at 20°C to 30°C, a thermal conductivity of 0.08 W / mK or more in the thickness direction of the fabric at 20°C to 30°C, and a contact coolness of 0.13 W / cm 2 above.

[0003] Patent Document 2 discloses a sheet-like fiber bundle assembly for bedding or mattresses having excellent cool-to-touch properties. The assembly is formed by laminating a plurality of sheets containing high-molecular polyethylene fibers having an average fiber length of 10 to 200 mm.

[0004] In addition, the applicant has proposed a sheet for absorbent articles that is not likely to cause discomfort when in contact with the skin even when wet (see Patent Document 3). The sheet contains hydrophobic fibers and cellulose fibers, and has a cool contact feeling q of 50% by weight on both sides of the sheet. max Both are 2.5kW / m 2 the following.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2010-236130

[0008] Patent Document 2: Japanese Patent Application Publication No. 2018-145577

[0009] Patent Document 3: Japanese Patent Application Publication No. 2019-42403 Summary of the invention

[0010] The invention relates to a sanitary nonwoven fabric.

[0011] In one embodiment, the sanitary nonwoven fabric includes fibers at least part of the surface of which contains a polyethylene resin.

[0012] In one embodiment, the volume filling rate of the sanitary nonwoven fabric is preferably 3.5% or more.

[0013] Furthermore, the present invention relates to an absorbent article comprising the above-mentioned sanitary nonwoven fabric.

[0014] Furthermore, the present invention relates to a sanitary product comprising the sanitary nonwoven fabric.

[0015] In one embodiment, the sanitary product includes a second member disposed adjacent to the sanitary nonwoven fabric.

[0016] In one embodiment, the second member has a strength of 9.8 mN / cm 2 (1gf / cm 2 ) The compression deformation under load is greater than 0.3 mm.

[0017] Furthermore, the present invention relates to a method for producing a sanitary nonwoven fabric, comprising subjecting a web of fibers at least a portion of the surface of which contains a polyethylene resin to a hot air treatment to obtain a fiber aggregate.

[0018] In one embodiment, the fiber aggregate is preferably subjected to a densification treatment.

[0019] Other features of the present invention will become apparent from the scope of the claims and the following description. DETAILED DESCRIPTION

[0020] Sanitary products such as sanitary napkins and panty liners that absorb fluids discharged from the body are composed of a combination of multiple components including nonwoven fabrics. If such products come into contact with the skin before or during use, the wearer will feel a sense of warmth, which may lead to discomfort such as stuffiness during use. This may become more pronounced in a hot summer environment. Therefore, it is desirable that the parts of sanitary products such as absorbent products that come into contact with the skin have a structure that allows the wearer to feel a cool feeling.

[0021] However, the technologies described in Patent Documents 1 and 2 are technologies applied to articles other than sanitary products such as clothing and bedding, and no research has been conducted on their application to sanitary products.

[0022] The technology described in Patent Document 3 is not likely to cause discomfort even when in contact with the skin in a wet state, but there is still room for improvement in how to reduce discomfort before using the absorbent article or when wearing the absorbent article and before absorbing liquid.

[0023] Therefore, the present invention relates to a sanitary nonwoven fabric that gives a cool feeling when in contact with the skin, thereby providing a comfortable feeling of use, and a sanitary product and an absorbent article having the same.

[0024] Hereinafter, the present invention will be described based on preferred embodiments of the present invention.

[0025] In the case where the upper limit or lower limit of a numerical value, or upper and lower limits, are specified in this specification, the value of the upper limit and lower limit itself is also included. In addition, even if not specifically stated, it should be understood that it records all numerical values ​​or numerical ranges below the upper limit of the numerical value or above the lower limit, or within the range of the upper and lower limits.

[0026] In this specification, "a" or "an" or the like means one or more than one.

[0027] It is understood that various modifications and changes of the present invention can be realized by comparing the above disclosure and the following disclosure in this specification. Therefore, it should be understood that within the technical scope of the content described in the scope of the patent claim, the present invention can also be implemented with respect to the embodiments not clearly described in this specification.

[0028] The contents of the above-mentioned patent documents and the following patent documents are all incorporated into this specification as part of the contents of this specification.

[0029] The sanitary nonwoven fabric of the present invention is suitable for use as a component of sanitary products. Typical examples of sanitary products include sanitary products such as face masks and eye masks, or absorbent articles for absorbing body fluids such as urine and menstrual blood, and absorbent articles are preferred.

[0030] The sanitary nonwoven fabric is disposed on the skin contacting surface side which contacts the skin of the wearer when the sanitary product is worn, or is disposed on a portion which contacts the user's hands when handling the sanitary product.

[0031] The sanitary nonwoven fabric can be used without being particularly limited to the uses described herein.

[0032] The sanitary nonwoven fabric of the present invention is a fiber sheet containing fibers at least part of the surface of which contains a polyethylene resin, and is preferably composed only of the fibers.

[0033] The constituent fibers of the sanitary nonwoven fabric are entangled, fused, and pressure-bonded with each other to maintain the form of a fiber sheet. Therefore, the sanitary nonwoven fabric of the present invention is mainly composed of constituent fibers in contact with each other with clear boundaries.

[0034] The fiber included in the sanitary nonwoven fabric has a polyethylene resin on at least a portion of the fiber surface. Examples of the presence of the polyethylene resin in the fiber included in the sanitary nonwoven fabric of the present invention include the following: (i) a mode in which the polyethylene resin is included on both the outer surface and the inside of the fiber, that is, a mode in which the constituent resin of the fiber is only the polyethylene resin; or (ii) a mode of a two-component composite fiber containing a low melting point component including the 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 portion of the fiber surface along the length direction.

[0035] It is known that polyethylene resin generally has a particularly high thermal conductivity among organic polymer materials. Therefore, from the viewpoint of making full use of the high thermal conductivity of the polyethylene resin itself and suppressing the decrease in thermal conductivity caused by the interface between the polyethylene resin and resins other than the polyethylene resin, so that the user feels a cool sensation, it is preferred to adopt the above-mentioned method (i).

[0036] As a specific example of the above (i), there can be mentioned: a fiber containing a single type of polyethylene resin as a constituent resin, or a fiber containing only a plurality of polyethylene resins as a constituent resin. As a specific example of the above (ii), there can be mentioned (a) core-sheath fibers, (b) parallel fibers, etc. (a) core-sheath fibers use a resin other than the polyethylene resin as a high melting point component as a core, and a sheath of the polyethylene resin as a low melting point component is formed in a manner covering the surface of the core, (b) parallel fibers use the polyethylene resin as a low melting point component, and a resin other than the polyethylene resin as a high melting point component, and the polyethylene resin as a low melting point component is continuously present on at least a portion of the fiber surface along the fiber length direction. The fiber used in the present invention may be solid or hollow. From the viewpoint of improving thermal conductivity and making it easy for the user to feel a cool feeling, solid fibers are preferred.

[0037] In the presence of the polyethylene resin in the fiber, it is preferred that the polyethylene resin is present on at least the entire outer surface of the fiber, and the entire fiber is preferably formed of the polyethylene resin. That is, it is preferred to have a core-sheath structure with the polyethylene resin as a sheath, or a solid fiber containing only the polyethylene resin. With such a configuration, the polyethylene resin with high thermal conductivity is in direct contact with the user's skin, so that the user can feel a strong cool sensation.

[0038] Especially, the fiber present in the sanitary nonwoven fabric is more preferably a fiber containing only polyethylene resin as its constituent resin. By using only polyethylene resin with high thermal conductivity, it is easy to constitute the fiber with high thermal conductivity, so the user can feel the cool feeling more strongly.

[0039] Examples of the polyethylene resin used in the present invention include low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), high-density polyethylene resin (HDPE), linear low-density polyethylene resin (LLDPE), and ethylene-propylene copolymers, etc. These can be used alone or in combination of two or more.

[0040] When an ethylene-propylene copolymer is used as the polyethylene resin, the ratio of the ethylene unit in the copolymer is preferably 95% by mass or more, more preferably 98% by mass or more, from the viewpoint of improving thermal conductivity.

[0041] The ratio of the propylene unit in the copolymer is preferably 5% by mass or less, more preferably 2% by mass or less.

[0042] Examples of the fiber composed only of a polyethylene resin include a fiber composed only of HDPE (ie, a fiber containing 100% by mass of HDPE), or a core-sheath fiber or a side-by-side fiber using a plurality of the above-mentioned various polyethylenes.

[0043] Examples of core-sheath fibers or parallel fibers using only polyethylene resin include: fibers in which the core and the sheath use HDPE with different melting points, respectively; core-sheath fibers in which the core uses one or more of LDPE and LLDPE and the sheath uses HDPE; core-sheath fibers in which the core uses HDPE and the sheath uses LLDPE; or parallel fibers in which HDPE is continuously present along the length direction on at least a portion of the surface of a fiber using LLDPE.

[0044] In the fiber containing only the polyethylene resin, the type or combination of the polyethylene resin may be adopted without being limited to the above.

[0045] Among them, from the viewpoint of having a high thermal conductivity and allowing the user to feel a stronger cool sensation, the polyethylene resin preferably contains HDPE, and more preferably contains only HDPE. That is, it is more preferable to use HDPE alone.

[0046] As resins other than polyethylene resins used in the present invention, for example, polyolefin resins other than polyethylene resins such as polypropylene (PP) and polybutene; polyester resins such as polyethylene terephthalate (PET); polyamide resins; vinyl resins such as polyvinyl chloride and polystyrene; acrylic resins such as polyacrylic acid and polymethyl methacrylate; fluororesins such as polyperfluoroethylene; and nylon, etc. These resins can be used alone or in combination of two or more.

[0047] 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, particularly preferably 100% by mass, relative to the total mass of the resin contained in the sanitary nonwoven fabric.

[0048] As another embodiment of the sanitary nonwoven fabric of the present invention, the sanitary nonwoven fabric preferably contains fibers having a thermal conductivity of a predetermined value or more in at least a part of the surface.

[0049] Specifically, the sanitary nonwoven fabric preferably contains fibers having a thermal conductivity of preferably 0.11 W / mK or more, more preferably 0.13 W / mK or more, and further preferably 0.15 W / mK or more, on a part of the surface.

[0050] Furthermore, realistically, sanitary nonwoven fabrics contain fibers having a thermal conductivity of 0.4 W / mK or less in a portion of the surface.

[0051] The thermal conductivity can be measured by, for example, melting a sanitary nonwoven fabric to obtain a film-like sample having a thickness of about 1 mm. The detailed measurement method will be described below.

[0052] By having such a thermal conductivity, the user of the sanitary product including the sanitary nonwoven fabric can feel a stronger sense of coolness.

[0053] The configuration related to thermal conductivity in this embodiment can be adopted instead of the above-mentioned embodiment or can be incorporated into the above-mentioned embodiment.

[0054] In addition, with regard to aspects not described in this embodiment, the above-described embodiment and the description related to each configuration can be appropriately applied.

[0055] The sanitary nonwoven fabric having the above thermal conductivity can be obtained, for example, by having a structure containing fibers including one or two or more of the polyethylene resins used in the above embodiment as constituent fibers.

[0056] In this case, the thermal conductivity of at least a portion of the surface constituting the fiber is preferably 0.11 W / mK or more, more preferably 0.13 W / mK or more, and further preferably 0.15 W / mK or more. If fibers having such thermal conductivity are used, it is easy to achieve the thermal conductivity range of the sanitary nonwoven fabric, which is preferred.

[0057] The above-mentioned thermal conductivity of the constituent fibers can be easily achieved by using fibers containing only polyethylene resin, for example.

[0058] Thermal conductivity can be measured, for example, by the following method. First, the nonwoven fabric or fiber to be measured is peeled off from the product by cold spray or the like, or fiber sampling or the like is performed to separate the fibers. Then, the separated nonwoven fabric or fiber is introduced into a heating and pressurizing device such as a press, and is heated at a temperature above the melting point of the nonwoven fabric or fiber raw material while being pressurized to form a film-like sample with a thickness of about 1 mm. At this time, the pressurizing conditions are appropriately adjusted so that air does not remain in the sample.

[0059] Then, the thermal conductivity was measured using a steady-state thermal conductivity measuring apparatus (KES-F6, manufactured by Kado Technology Co., Ltd.) based on the amount of heat transferred from a 30° C. hot plate via the sample to a 20° C. hot plate. The measurement was performed at 10 locations on one film-like sample, and the value of the highest thermal conductivity was defined as the thermal conductivity (W / mK) in the present invention.

[0060] The sanitary nonwoven fabric of the present invention preferably has a volume filling rate of 3.5% or more, more preferably 7.0% or more, further preferably 10.0% or more, still 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.

[0061] When used as a disposable sanitary material that comes into contact with the user's skin, the volume filling rate is preferably 60.0% or less, more preferably 50.0% or less, and even more preferably 30.0% or less from the viewpoint of improving the texture.

[0062] By having such a volume filling ratio, the content of air having low thermal conductivity in the sanitary nonwoven fabric is reduced, so that the heat transfer property can be improved, thereby allowing the user to feel a stronger cooling sensation.

[0063] In addition, the texture of the fiber sheet and the sanitary products in which the fiber sheet is placed can be fully expressed.

[0064] The above structure can be obtained, for example, by compressing the fiber sheet as in the following production method. When the sanitary nonwoven fabric has a density gradient, the volume filling rate of the outermost layer that contacts the user's skin is within the above range.

[0065] The above-mentioned structure related to the volume filling rate can be applied to each embodiment of a sanitary nonwoven fabric containing fibers at least part of the surface of which contains a polyethylene resin, a sanitary nonwoven fabric having a thermal conductivity of a predetermined value or more on the surface of the fibers, and a sanitary nonwoven fabric having a thermal conductivity of a predetermined value or more.

[0066] The volume filling rate in the present invention can be expressed as a percentage of the apparent volume to the actual volume. In detail, a specified area of ​​the sanitary nonwoven fabric to be measured is cut off as a measurement sample, and its mass (g) is measured. The specified area when cutting the measurement sample is preferably 10 cm square, but if a measurement sample of this size cannot be cut out, then the sanitary nonwoven fabric to be measured is cut off in an area where the unit area weight is uniform under visual observation, with a width and length that is as large as possible. Then, the unit area weight A (g / cm 2 ).

[0067] In addition, the method for measuring the thickness B (cm) of the measurement sample is as follows. First, only a 12.59g (55mm diameter) plate is placed on a laser displacement meter (LK-080 manufactured by Keyence Corporation. The laser displacement meters in this specification are all this laser displacement meter), and the measured thickness is set to zero to perform zero point adjustment. Then, the above-mentioned plate is placed on the measurement sample, and the thickness in this state is measured using the laser displacement meter, and the thickness is set to the thickness B (cm) of the measurement sample. In the measurement of thickness B, a force of 4.9mN / cm is given to the measurement sample by the placement of the plate. 2 of load.

[0068] In addition, the density C (g / cm 3 ), and calculate the volume filling rate (%) according to the following formula.

[0069] Volume filling rate (%) = 100 × (A) / (B × C)

[0070] When a sanitary nonwoven fabric to be measured is placed in a sanitary product such as an absorbent article, a cold spray is blown onto the sanitary product to cure the hot melt adhesive, and then the sanitary nonwoven fabric to be measured is carefully peeled off. This method is also common to other measurements in this specification.

[0071] Since the sanitary nonwoven fabric having the above structure uses fibers having a polyethylene resin with high thermal conductivity among synthetic resins on at least a portion of its surface, when the fibers come into contact with the user's skin, the heat caused by the user's body temperature can be quickly transferred from the user to the sanitary nonwoven fabric or other fibers that are not in contact with the user.

[0072] Furthermore, by making the volume filling rate of the sanitary nonwoven fabric within a specified range, the good texture of the fiber sheet can be exhibited, and the content of air with low thermal conductivity in the sanitary nonwoven fabric can be reduced, thereby allowing the heat generated by the user to be quickly transferred to the sanitary nonwoven fabric side.

[0073] As a result, when the user's skin comes into contact with the sanitary nonwoven fabric, the user can feel a cool sensation, and the cool sensation brings a comfortable feeling of use.

[0074] According to a preferred embodiment of the present invention, the user can feel a stronger cooling sensation, thus contributing to further improving the feeling of use.

[0075] Furthermore, by configuring the sanitary nonwoven fabric to include fibers, the contact area between the user's skin and the sanitary nonwoven fabric can be increased, so that the user can feel a cool sensation, and the softness due to the configuration of the nonwoven fabric can be exhibited.

[0076] The fibers constituting the sanitary nonwoven fabric are preferably in contact with each other, and more preferably in contact with each other at multiple points. Thus, the heat generated by contact with the user's skin can be transferred in multiple directions, so that the heat generated by the user's body temperature can be transferred with high efficiency, and as a result, the user can feel a cool sensation more efficiently.

[0077] The term “contact” in the present invention includes two aspects: a aspect in which fibers are in contact with each other with clear boundaries between the fibers; and a aspect in which the fibers are partially fused with each other, so that the boundaries between the fibers are unclear.

[0078] "Multi-point contact" in the present invention means that when the nonwoven fabric is cut in a direction perpendicular to the extension 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 connected to the fiber F are connected to the fiber F at more than two points.

[0079] The structure in which the fibers are in contact at multiple points can be obtained, for example, by using fibers having a non-circular cross-sectional shape such as an elliptical or multilobal shape as described below and subjecting the raw nonwoven fabric to a densification treatment such as compression in the following production process.

[0080] When the fibers of the sanitary nonwoven fabric are in contact with each other, it is also preferred that the contact is formed by fusion or crimping. By adopting such a structure, the contact area between the fibers can be increased, thereby further improving the heat transfer efficiency. As a result, a cool feeling can be efficiently given to the user.

[0081] Fusion refers to a method in which the fibers are melted by simply applying heat or applying heat and pressure to a plurality of fibers, thereby blurring the boundaries between the fibers.

[0082] The so-called pressure bonding refers to a method in which a plurality of fibers are brought into contact with each other with clear boundaries between the fibers by simply applying pressure to the fibers, and gaps between the fibers are allowed to exist. The above-mentioned "multi-point contact" method is also preferred in the pressure bonding.

[0083] The cross-sectional shape of the fibers constituting the sanitary nonwoven fabric may be, for example, a circle such as a perfect circle and an ellipse, a convex polygon such as a triangle, a quadrilateral, a pentagon, and a hexagon, or a regular polygon. In addition to these geometric shapes, a multi-lobed shape having a structure with a plurality of concave and convex portions along the periphery of the cross section may also be used.

[0084] The "cross-sectional shape" in the present invention refers to the shape of the fibers constituting the sanitary nonwoven fabric when observing a cross section perpendicular to the direction in which the fibers constitute the sanitary nonwoven fabric.

[0085] The cross-sectional shape of the fiber is preferably a non-circular shape, and more preferably an ellipse, or a shape obtained by combining an ellipse and a multi-lobed shape, etc., with a major axis and a minor axis. 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 contact area between the fibers can be increased, thereby further improving the heat transfer efficiency, so that the user can feel a cool feeling more effectively.

[0086] 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.

[0087] From the viewpoint of improving the spinnability during fiber production and enhancing production efficiency, the ratio is preferably 10 or less, more preferably 8 or less, and even more preferably 5 or less.

[0088] In addition, it is preferable that the above ratio is satisfied over the entire length of the fiber.

[0089] 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 method. First, the nonwoven fabric to be measured is cooled with liquid nitrogen, and then the nonwoven fabric is 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 is observed using a scanning electron microscope (SEM) at any magnification sufficient to identify the fiber cross section and measure the size of the fiber cross section.

[0090] Take any 10 fibers as the object, observe each cross section independently, connect two points on the periphery of the fiber cross section according to the scanning electron microscope image of each fiber, set the line segment with the maximum diameter through the centroid of the fiber cross section as the major axis, and set the maximum width of the minor axis orthogonal to the major axis as the minor axis (in the case of a special-shaped cross section with multiple concave and convex parts on the periphery, the minimum width of the minor axis corresponding to the concave part is not considered). The arithmetic mean of these is set as the major axis length or the minor axis length in the present invention.

[0091] When the cross-sectional shape of the fiber is a cross-sectional shape having a plurality of irregularities on the outer periphery such as a multi-lobal shape, an ellipse approximation process is performed based on the periphery of the fiber cross section using scanning electron microscope images of each fiber cross section obtained for arbitrary 10 fibers using image processing software, etc. The arithmetic mean calculated based on the lengths of the major axis and minor axis of the ellipse obtained by the process is set as the major axis length or minor axis length in the present invention.

[0092] From the viewpoint of improving the texture of the nonwoven fabric, the thickness of the sanitary nonwoven fabric of the present invention is preferably 0.1 mm or more, more preferably 0.2 mm or more, and even more preferably 0.3 mm or more.

[0093] In addition, from the viewpoint of reducing the air content in the nonwoven fabric to improve thermal conductivity, the thickness of the sanitary nonwoven fabric of the present invention is preferably 3 mm or less, more preferably 1.5 mm or less, and even more preferably 0.5 mm or less.

[0094] The thickness of the sanitary nonwoven fabric is set at 4.9 mN / cm 2 (0.5gf / cm 2 ) is measured using a laser displacement meter or the like under load.

[0095] By setting the thickness of the sanitary nonwoven fabric to the above configuration, the heat capacity of the sanitary nonwoven fabric can be increased, and the sanitary nonwoven fabric that can efficiently give a cool feeling to the user can be efficiently manufactured.

[0096] In addition, the weight per unit area of ​​the sanitary nonwoven fabric of the present invention is preferably 15 g / m 2 More preferably 20 g / m 2 More preferably, 25 g / m 2 above.

[0097] In addition, the weight per unit area of ​​the sanitary nonwoven fabric of the present invention is preferably 140 g / m 2 Below, more preferably 90g / m 2 Below, more preferably 50g / m 2 the following.

[0098] With the above configuration, the difference in cool feeling caused by uneven weight per unit area of ​​the sanitary nonwoven fabric can be reduced, and the fibers can be effectively fused and compacted, so that a sanitary nonwoven fabric having a predetermined volume filling rate can be produced with high productivity.

[0099] The cool feeling of the sanitary nonwoven fabric of the present invention is max Preferably 0.06W / m 2 More preferably 0.08W / m 2 More preferably, 0.10 W / m 2 Above, and preferably 0.80W / m 2 Below, more preferably 0.60W / m 2 Below, more preferably 0.50 W / m 2 the following.

[0100] Specifically, the cool touch feeling of sanitary nonwoven fabrics max Preferably 0.06W / m 2 Above and 0.80W / m 2 Below, more preferably 0.08W / m 2 Above and 0.60W / m 2Below, more preferably 0.10 W / m 2 Above and 0.50W / m 2 the following.

[0101] Cool touch max For example, it can be measured by the following method.

[0102] First, a test piece was cut out from a sanitary nonwoven fabric to be measured so as to have a size of 10 cm in length×10 cm in width, and the test piece was left to stand in an environment of room temperature 23° C. and relative humidity 50% for 24 hours.

[0103] Then, under this environment, the test piece is placed on the measuring table and fixed to the measuring table using double-sided tape. A constant temperature device using gas or liquid as a heat medium is used as the measuring table.

[0104] Then, the contact coolness q of the measurement object was measured by a measuring device (KES-F7 Thermo Lab II manufactured by Kado Technology Co., Ltd.) according to the measurement instructions of the device. max Carry out determination.

[0105] Specifically, the usable area is 9.0 cm 2 A pure copper plate with a mass of 9.8 g is used as a hot plate in contact with the object to be measured. The initial temperature of the copper plate is set to 33°C (a temperature 10°C higher than the surface temperature of the object to be measured), and the contact pressure between the copper plate and the object to be measured is set to 1 kPa. The copper plate is brought into contact with the test piece, and the value of the heat flow at the moment of contact is set to zero, and the maximum value of the heat flow is measured.

[0106] This measurement was performed 5 times for each measurement target surface, and the arithmetic mean of the obtained multiple measurement values ​​was set as the contact coolness q of the measurement target. max (W / m 2 ).

[0107] The so-called cool contact feeling is a value obtained by quantifying the cool skin feeling when the skin touches an object. The cool contact feeling varies depending on the amount of heat transferred from the skin to the object when the skin touches the object. The greater the heat transfer, the cooler the contact feeling. max Corresponding to the maximum value of the heat transfer from the skin to the object, the contact coolness q max The value of q is as follows: the cooler the object is when in contact with it, the larger the value is, and the warmer the object is when in contact with it, the smaller the value is. max When the value of is within the above range, the cooling sensation can be felt more effectively.

[0108] The sanitary nonwoven fabric of the present invention is a sheet-like article having two surfaces, wherein the existence ratio of the constituent fibers on the surface of the sanitary nonwoven fabric (hereinafter also referred to as "fiber surface existence ratio") is preferably greater than a specified value. It should be noted that the surface of the sanitary nonwoven fabric refers to the area from the outermost surface of the sanitary nonwoven fabric to the area 20 μm away from it in the thickness direction. The outermost surface of the sanitary nonwoven fabric refers to the surface orthogonal to the thickness direction of the sanitary nonwoven fabric formed by the outermost portion in the thickness direction in the image when the sanitary nonwoven fabric is cut in the thickness direction and the cross section along the thickness direction is observed using a scanning electron microscope (SEM).

[0109] Specifically, the fiber surface presence ratio of the sanitary nonwoven fabric is preferably 40% or more, more preferably 45% or more, and even more preferably 50% or more, and is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less.

[0110] More specifically, the fiber surface abundance ratio of the sanitary nonwoven fabric is preferably 40% to 90%, more preferably 45% to 85%, and even more preferably 50% to 80%.

[0111] The fiber surface existence ratio is a ratio obtained by focusing on the existence ratio of the fiber to express the relationship between the constituent fibers and the gaps between the fibers on the surface of the nonwoven fabric. Therefore, by making the fiber surface existence ratio within the above range, the air content in the fiber can be reduced to obtain a higher cool feeling.

[0112] The fiber surface abundance ratio can be measured as a ratio based on area, for example, according to the following method.

[0113] In detail, two parts are randomly cut from the sanitary nonwoven fabric of the measurement object with a slice size of 4 cm × 4 cm as a sample. Using a scanning electron microscope (SEM), one side of the obtained sample is measured under the conditions of a voltage of 15 kV and a magnification of 50 times to obtain a SEM image. Then, using the image processing software WinROOF2018 (manufactured by Mitani Shoji Co., Ltd.), the SEM image is binarized with a threshold value of 121 to 255, and the area calculation function built into the above software is used to measure and calculate the ratio of the area of ​​the binarized bright (white) part to the area of ​​the entire image, and the area ratio is set as the fiber surface presence rate of the present invention.

[0114] When it is difficult to measure by the above method, the threshold value is set to a value of 70 to 255, the image is binarized, and the area ratio of the bright color portion is measured.

[0115] The sanitary nonwoven fabric of the present invention is preferably arranged such that the fibers constituting the nonwoven fabric have a certain orientation.

[0116] With this structure, heat transfer is easily generated along the longitudinal direction of the fibers, making it easier for the user to feel a cool sensation.

[0117] More specifically, it is preferred that the sanitary nonwoven fabric of the present invention has the fiber length direction of the fibers of the nonwoven fabric substantially parallel to the horizontal plane when the nonwoven fabric is placed still on the horizontal plane.

[0118] In addition, or alternatively, it is preferred that the fiber extends in one direction when the sanitary nonwoven fabric is viewed from above. For example, when the sanitary nonwoven fabric is viewed from above, considering the first direction of the sanitary nonwoven fabric and the second direction orthogonal to the first direction, it is further preferred that the fiber extends in the same direction as the first direction or the second direction of the nonwoven fabric. In the case where the fibers have intersections, it is desired that the angles formed by the fibers having the intersections when the sanitary nonwoven fabric is viewed from above account for more than 50%. The so-called obtuse angle refers to an angle greater than 90°.

[0119] Regarding the quantitative determination of the angles between the fibers, any three locations of the sanitary nonwoven fabric can be photographed with a SEM at a magnification such that about 10 intersections of the fibers can be confirmed within the field of view, and the image data obtained can be measured and counted using image analysis software attached to the SEM or any image analysis software. Alternatively, if image analysis software is not available, the obtained image data can be printed, the angles between the fibers can be confirmed using an angle measuring device such as a protractor, and the angles can be written into a data table for statistics.

[0120] By having at least one of the above-mentioned structures related to the orientation of the fibers, heat transfer can be easily advanced in a certain direction, thereby making it easier for the user to feel a cool sensation more effectively.

[0121] This structure can be obtained, for example, by manufacturing a long sheet using short fibers of HDPE as a material, conveying the long sheet while applying tension to the long sheet in the conveying direction, and fusing the fibers to each other by a hot air method, or spinning HDPE fibers onto a conveying device such as a belt conveyor while conveying the fibers in one direction.

[0122] In the above description, for the sake of convenience, the sanitary nonwoven fabric has a single fiber layer and the single fiber layer contains fibers containing polyethylene resin on at least a portion of the surface (regardless of whether it contains only a single fiber or is blended with other fibers), but it is not limited to this form. In detail, the sanitary nonwoven fabric may also have a plurality of fiber layers of two or more layers.

[0123] As an embodiment of the sanitary nonwoven fabric, for example, it comprises at least: a fiber layer containing a first fiber whose surface at least partly contains a polyethylene resin (hereinafter, also referred to as the first fiber layer), and a second fiber layer containing fibers other than the first fiber arranged adjacent to the fiber layer (hereinafter, also referred to as the second fiber layer). Adjacent here means that the fiber layers are adjacent to each other without interposing other fiber layers, but an adhesive is allowed to be interposed between the fiber layers.

[0124] In this case, from the viewpoint of more effectively feeling the cool feeling, it is preferred that the first fiber layer constitutes the outer surface of the sanitary nonwoven fabric. In addition, based on the same viewpoint, it is preferred that at least the first fiber layer satisfies various preferred forms related to the above-mentioned sanitary nonwoven fabric, and more preferably satisfies the above-mentioned preferred forms in the entire sanitary nonwoven fabric.

[0125] Specifically, the multilayered sanitary nonwoven fabric can be obtained, for example, by performing hot air processing or spunbonding processing on a fiber web containing a first fiber whose surface at least partly contains a polyethylene resin and a second fiber web containing fibers other than the first fiber in a laminated state. In this case, the boundary between each fiber layer is usually unclear, but a portion where the boundary is clear may also be included. In the case of this method, each fiber layer maintains the form of the fiber sheet by, for example, at least one of mutual entanglement, fusion and crimping.

[0126] As another embodiment of the multilayered sanitary nonwoven fabric, there can be mentioned a method in which a fiber web or fiber sheet containing first fibers whose surface at least partly contains a polyethylene resin is bonded to a fiber web or fiber sheet containing fibers other than the first fibers by an adhesive, thereby maintaining the fiber sheet. In this case, the boundaries between the fiber layers are usually clear.

[0127] In either embodiment, fibers other than the first fibers include fibers containing the above-mentioned constituent resins such as PET resin and PP resin, and one or more of pulp fibers, rayon fibers, and hydrophilized fibers.

[0128] The weight per unit area of ​​the second fiber layer is preferably 15 g / m 2 More preferably 20 g / m 2 More preferably, 25 g / m 2 More than, preferably 140g / m 2 Below, more preferably 90g / m 2 Below, more preferably 70g / m 2 the following.

[0129] The sanitary nonwoven fabric may be used as it is, or may be used as a constituent member of a sanitary product to produce a sanitary product having the sanitary nonwoven fabric.

[0130] Furthermore, when the sanitary nonwoven fabric of the present invention is incorporated into a sanitary product, it is preferred that the nonwoven fabric forms a surface facing the skin of the user.

[0131] In either case, it is typically disposable.

[0132] Sanitary products including the sanitary nonwoven fabric of the present invention are, for example, absorbent articles, etc. That is, the sanitary nonwoven fabric can be used as a constituent member of absorbent articles, etc.

[0133] Typically, absorbent articles include a front sheet and a back sheet, and an absorber disposed between the front sheet and the back sheet, and can be used in a state where a sanitary nonwoven fabric is disposed in addition to the front sheet or the back sheet, or in a state where a sanitary nonwoven fabric is disposed instead of the front sheet or the back sheet. Examples of absorbent articles include disposable diapers, urine leakage pads, sanitary napkins for menstruation, sanitary pads, etc., but are not limited to these, and widely include articles for absorbing liquid discharged from the human body.

[0134] When the sanitary nonwoven fabric is used as a component of an absorbent article, the sanitary nonwoven fabric can be placed in a position that comes into direct contact with the user's skin when the absorbent article or other sanitary product is used or when the absorbent article or other sanitary product is taken out of a package. That is, the sanitary nonwoven fabric is preferably placed on the outer surface of the absorbent article or other sanitary product.

[0135] The so-called outer surface of sanitary products such as absorbent articles refers to the surface of sanitary products such as absorbent articles that can be touched by the user with hands after the package is opened and the sanitary products such as absorbent articles are taken out (including the front and back sides, the surface side in the thickness direction rather than the internal surface).

[0136] That is, the sanitary nonwoven fabric constituting the sanitary product may be disposed on the surface facing the skin of the wearer wearing the sanitary product or on the surface not facing the skin of the wearer wearing the sanitary product, and may constitute a package of the sanitary product.

[0137] Specifically, when a sanitary nonwoven fabric is used in an absorbent article as an embodiment of a sanitary product, such as a disposable diaper, it can be used as a component member such as a front sheet, a side nonwoven fabric, waist pleats, pleats arranged near the groin, and an outer packaging body.

[0138] In addition, when sanitary nonwoven fabrics are used in absorbent articles as an embodiment of sanitary products, such as urine leakage pads and menstrual sanitary napkins, they can be used as components such as front sheets, side nonwoven fabrics, buttocks protection, or bags for individual packaging.

[0139] When a sanitary nonwoven fabric is used in an absorbent article as an embodiment of a sanitary product, such as a urine leakage pad or a sanitary napkin, it can be used as a structural member such as a topsheet or gathers arranged near the groin.

[0140] In particular, from the perspective of providing a cool feeling when using sanitary products such as absorbent articles and reducing discomfort caused by stuffiness, the sanitary nonwoven fabric is preferably configured in the following manner so that when the sanitary product of the absorbent article is worn in the correct position, it constitutes the side opposite to the skin of the wearer of the sanitary product wearing the absorbent article (hereinafter also referred to as the "skin-opposing side").

[0141] Furthermore, it is also preferable that the sanitary nonwoven fabric is disposed at a portion of the sanitary article of the absorbent article which comes into direct contact with the skin of the wearer when the absorbent article is worn.

[0142] As a structural member of such an absorbent article, a surface sheet, a side nonwoven fabric, waist gathers, gathers arranged near the groin, etc. are mentioned, for example.

[0143] The front sheet used in the absorbent article is a sheet constituting the skin-opposite side, and the back sheet is a sheet constituting the side facing the side opposite to the skin of the wearer wearing the absorbent article (hereinafter also referred to as the "non-skin-opposite side"). When using materials other than the sanitary nonwoven fabric of the present invention for the front sheet and the back sheet used in the absorbent article, materials previously used in absorbent articles can be used without particular restrictions. As the front sheet, for example, various nonwoven fabrics with liquid permeability, perforated films, etc. can be used. As the back sheet, a sheet with poor liquid permeability or hydrophobicity or liquid permeability can be used. As the former, there can be cited: resin films, laminates of resin films and nonwoven fabrics, etc. The latter can use the same as the front sheet.

[0144] The absorbent used in absorbent articles has an absorbent core. The absorbent core is composed of, for example, a fiber stack of hydrophilic fibers such as cellulose represented by pulp, a mixed fiber stack of the hydrophilic fibers and a water-absorbent polymer, a stack of a water-absorbent polymer, and typically contains hydrophilic fibers and a water-absorbent polymer.

[0145] The absorbent core may also be covered by a core wrapping material. As a covering method of the core wrapping material, for example, at least the skin-facing surface may be covered by a liquid-permeable core wrapping material, or the entire surface including the skin-facing surface and the non-skin-facing surface may be covered by the core wrapping material. As the core wrapping material, for example, a thin sheet of paper containing hydrophilic fibers or a liquid-permeable nonwoven fabric may be used.

[0146] From the viewpoint of preventing the constituent fibers from getting tangled in the skin and ensuring a good touch for the user, the fiber diameter of the fibers used in the sanitary nonwoven fabric is preferably 3 μm or more, more preferably 5 μm or more.

[0147] In addition, from the viewpoint of reducing the inter-fiber gaps in the nonwoven fabric, thereby reducing the air content in the nonwoven fabric and improving thermal conductivity, the fiber diameter of the fibers used in the sanitary nonwoven fabric is preferably 70 μm or less, more preferably 50 μm or less.

[0148] Regarding the fiber diameter of the fiber, the same method as the method for measuring the lengths of the major axis and the minor axis of the cross-sectional shape of the fiber is used to prepare the measurement sample and perform SEM observation, and the fiber diameters of 10 fibers are measured for each sample, and the arithmetic mean thereof is set as the fiber diameter of the present invention. In the case where the fiber is not a perfect circle, the lengths of the major axis and the minor axis of the fiber are measured by the above method, and the arithmetic mean of the length of the major axis and the length of the minor axis of one fiber is set as the fiber diameter, and the arithmetic mean of the diameters of the 10 fibers is set as the fiber diameter of the fiber of the present invention.

[0149] As long as the effects of the present invention can be exerted, the sanitary nonwoven fabric of the present invention may further contain a filler for improving thermal conductivity. Such fillers include, for example, at least one of titanium oxide, aluminum oxide, boron nitride, magnesium oxide, silicon dioxide, carbon black, and carbon nanotubes. The filler may be present in the fiber, between the fibers, or partially exposed on the fiber surface and embedded in the fiber.

[0150] When sanitary products are made using the sanitary nonwoven fabric of the present invention, the sanitary products may include other components (hereinafter, the components are also referred to as "second components") in addition to the sanitary nonwoven fabric as an aggregate of fibers containing a polyethylene resin at least part of the surface (hereinafter, for convenience of explanation, this is also referred to as "first fiber aggregate").

[0151] As an embodiment of the sanitary article provided with the second member, for example, at least one of an absorbent sheet containing an absorbent polymer and fibers, and an absorbent containing an absorbent polymer and fibers can be used as the second member. These are examples of fiber assemblies different from sanitary nonwoven fabrics. As sanitary articles having these second members, the above-mentioned absorbent articles can be preferably cited.

[0152] That is, in this embodiment, a sanitary nonwoven fabric as the first fiber assembly and an absorbent sheet and / or absorbent as the second member are arranged as the constituent materials of the sanitary article. It is also preferred that the first fiber assembly and the second member are arranged adjacent to each other. The fiber assemblies in this embodiment may or may not be joined to each other.

[0153] As the absorbent sheet, for example, the absorbent sheet described in Japanese Patent Application Laid-Open No. 8-246395 can be used.

[0154] When the sanitary product includes the second member, or when the sanitary nonwoven fabric includes the second fiber layer, it is preferred that the second member or the second fiber layer has a thickness variation of at least a predetermined value.

[0155] Specifically, the second member is 9.8 mN / cm 2 (1gf / cm 2 ) is preferably 0.3 mm or more, more preferably 0.5 mm or more. In addition, the compressive deformation of the second member under the load is preferably 3 mm or less. As described below, the compressive deformation is the thickness of the second member under no load conditions minus 9.8 mN / cm 2 (1gf / cm 2 ) is expressed as the change in the thickness of the second component under the load.

[0156] Preferably, the second fiber layer constituting the sanitary nonwoven fabric also has the same compression deformation. In addition, when the sanitary product has both the sanitary nonwoven fabric and the second member of the multilayer structure, preferably the second member and the second fiber layer respectively satisfy the above-mentioned compression deformation.

[0157] With this structure, when the first fiber assembly including fibers containing polyethylene resin at least partially on the surface contacts the wearer, the first fiber assembly easily deforms following the deformation of the second member, thereby increasing the contact area with the wearer and efficiently making the wearer feel cool.

[0158] Regarding the second fiber layer having the above-mentioned physical properties, for example, in the following manufacturing method, fibers containing PET resin, PP resin, or PET / HDPE core-sheath composite fibers are used as constituent fibers, which are subjected to hot air treatment to obtain a fiber web, and then the fiber web is used to obtain the second fiber layer.

[0159] When the second member is an absorbent sheet or absorbent body, it can be obtained by, for example, appropriately adjusting the basis weight of fibers, fiber sheets, and water-absorbent polymers constituting the absorbent sheet or absorbent body.

[0160] The thickness of the second member or the second fiber layer can be measured, for example, by the following method.

[0161] First, the cross section of the object to be measured is observed visually or by SEM, and the fiber diameter, the distance between fibers, or the boundary between components are observed to confirm whether it is a sanitary nonwoven fabric having multiple fiber layers, or whether there is a sanitary nonwoven fabric and a second component other than the sanitary nonwoven fabric.

[0162] When the object to be measured is a sanitary product, the sanitary product is immersed in liquid nitrogen to fix the structure, and then the sanitary nonwoven fabric and the second member other than the sanitary nonwoven fabric are carefully peeled off from the sanitary product to be measured to separate them. Then, the separated member is used for the contact coolness q described in detail in the following examples. max The determination of q max The fiber sheet having the highest value of is set as the sanitary nonwoven fabric, and the member adjacent to the sanitary nonwoven fabric is set as the second member.

[0163] Then, a plate was placed, and a force of 9.8 mN / cm was applied to the separated second member. 2 (1gf / cm 2 ) is loaded, a laser displacement meter is used to measure the thickness in this state, and the thickness is set as the thickness of the second component.

[0164] When the object to be measured is a multilayered sanitary nonwoven fabric, the q max The fiber layer on the side with the highest value of is defined as a first fiber layer, and the fiber layer adjacent to the first fiber layer is defined as a second fiber layer, and the second fiber layer is used for the above measurement.

[0165] In addition, in sanitary products as a whole, 9.8mN / cm 2 (1gf / cm 2 ) The compression deformation under the load is preferably 0.3 mm or more, more preferably 0.4 mm or more. In addition, the compression deformation of the sanitary product as a whole under the load is preferably 15 mm or less, more preferably 10 mm or less.

[0166] This structure can make the nonwoven fabric as a whole soft and improve the feel during use, and can increase the contact area between the first fiber assembly including fibers containing polyethylene resin at least partially on the surface and the wearer, so that the wearer can feel cool efficiently.

[0167] Regarding the above-mentioned compression deformation, for example, if it is a hot air method, it can be easily achieved by the following structure, that is, making the temperature or wind speed of the hot air lower than the conditions normally used, or increasing the number of fibers or using fibers containing a resin with a melting point higher than the hot air temperature, thereby reducing the fusibility between the fibers.

[0168] This can be easily achieved by adopting the following structures in addition to the above-mentioned structures, or by adopting the following structures instead of the above-mentioned structures, namely, providing two or more fiber layers, and providing only one fiber layer with a layer having a higher compression deformation amount than the other fiber layers; or increasing the unit area weight of one fiber layer compared with the other fiber layers; or blending fibers with a high melting point into one fiber layer.

[0169] The amount of compression deformation can be measured, for example, using a KES-FB-3 compression tester manufactured by Kato Technology Co., Ltd. A certain size of slice is cut from the sanitary nonwoven fabric to be measured and used as a sample. The sample is mounted on the test bench of the test machine and placed on a surface having an area of ​​2 cm 2 The compression speed is 0.02mm / sec and the maximum compression load is 9.8mN / cm 2 (1gf / cm 2 ). The thickness under no-load condition is set to thickness T0 (mm), and 9.8 mN / cm 2 (1gf / cm 2 ) When the thickness under load is set to thickness Tm (mm), the compressive deformation amount (mm) can be calculated as "T0-Tm" which is the thickness T0 minus the thickness Tm.

[0170] When the second member is an absorbent sheet, the overall weight per unit area is preferably 40 g / m 2 More preferably 60g / m 2 More preferably, 70 g / m 2 More than, preferably 500g / m 2 Below, more preferably 400g / m 2 Below, more preferably 300g / m 2 the following.

[0171] When the second member is an absorbent body, the overall weight per unit area is preferably 30 g / m 2 More preferably 40g / m 2 More preferably, 50 g / m 2 More than, preferably 600g / m 2 Below, more preferably 550g / m 2 Below, more preferably 500g / m 2 the following.

[0172] The above is a description of the sanitary nonwoven fabric of the present invention and sanitary products (including absorbent articles) having the sanitary nonwoven fabric. The preferred method for producing the sanitary nonwoven fabric of the present invention is described below. The production method comprises a step (hot air step) of obtaining a fiber assembly by hot air treatment of a web of fibers having at least a portion of its surface containing a polyethylene resin.

[0173] In addition to this, it is preferred to further employ a step of subjecting the obtained fiber aggregate to a densification treatment (densification step).

[0174] Furthermore, it is also preferred that the thermal conductivity of the fiber used in the present production method be within the above-mentioned value range.

[0175] First, a web of fibers whose surface at least partially includes a polyethylene resin is formed. The fiber web can be formed, for example, by a carding method using a known carding machine.

[0176] Then, a hot air treatment is performed by blowing hot air to the fiber web to obtain a fiber aggregate having a polyethylene resin on at least a portion of the surface. This step is a step of converting the fiber web into a nonwoven fabric, and the fiber aggregate produced in this way is generally called a hot air nonwoven fabric.

[0177] Generally speaking, when hot-air processing is performed on a fiber web containing polyethylene resin, from the viewpoint of manufacturing efficiency, core-sheath fibers having polyethylene resin as a sheath and a high melting point resin other than polyethylene resin as a core are mainly used, and it is extremely difficult to form a nonwoven fabric of a fiber containing only polyethylene resin by hot-air processing. In addition, the use of core-sheath fibers is conducive to improving the texture and strength of the obtained hot-air nonwoven fabric, but there is still room for improvement in terms of improving thermal conductivity to make the user feel cool.

[0178] The present inventors have made intensive studies on these improvements and have found that by controlling the temperature and wind speed of the hot air in the hot air process, a hot air nonwoven fabric having good texture and strength can be efficiently manufactured even when using fibers containing only polyethylene resin.

[0179] The temperature and wind speed of the hot air blown to the fiber web in the hot air step are preferably within a specific range. Specifically, from the viewpoint of making the texture of the obtained sanitary nonwoven fabric good, the temperature of the hot air blown to the fiber web is preferably within the range of the melting point M+4°C or less, more preferably within the range of the melting point M+3°C or less, and further preferably within the range of the melting point M+2°C or less, in terms of the relationship with the melting point M (°C) of the resin contained in the fiber surface constituting the fiber web.

[0180] In addition, from the perspective of appropriately fusing the fibers constituting the fiber web to each other so that the sanitary nonwoven fabric exhibits durable strength, the temperature of the hot air blown to the fiber web may preferably be in the range of above the melting point M-4°C, more preferably in the range of above the melting point M-2°C, and further preferably in the range of above the temperature of the melting point M.

[0181] The temperature of the hot air is the temperature of the hot air at the outlet, which can be measured by installing a thermocouple at the outlet or at a position as close to the outlet as possible.

[0182] For example, when fibers having HDPE (melting point M: 130° C.) on their surfaces are used as fibers constituting the fiber web, the temperature of the hot air is preferably 126° C. or higher, more preferably 128° C. or higher, and further preferably 130° C. or higher.

[0183] The temperature of the hot air under the above conditions may be preferably 134° C. or lower, more preferably 133° C. or lower, and further preferably 132° C. or lower.

[0184] The melting point M of the resin constituting the fiber surface can be measured using a differential scanning calorimeter (DSC7000x manufactured by Hitachi High-Tech Science Co., Ltd.). First, a fiber sample (1 mg) cut into small pieces is used to perform thermal analysis of the sample at a heating rate of 10°C / min to measure the melting peak temperature of each resin. The melting point is defined as the melting peak temperature at the first heating. When a clear melting point cannot be determined by this method, the resin is defined as a "resin without a melting point". In the case of a resin without a melting point, the softening point is set to the melting point M.

[0185] In the hot air step, the wind speed of the hot air blown onto the fiber web is preferably 0.6 m / sec or more, more preferably 1 m / sec or more, from the viewpoint of allowing the hot air to sufficiently pass through the fiber web in the thickness direction to facilitate fusion of the fibers.

[0186] In addition, from the same viewpoint, the wind speed of the hot air blown onto the fiber web is preferably 2 m / sec or less, and more preferably 1.4 m / sec or less.

[0187] By carrying out the hot air process under the above-mentioned temperature and wind speed conditions, the polyethylene resin existing on the surface of the fibers constituting the fiber web can be melted or softened, and random areas where the fibers are fused to each other are formed. Therefore, the sanitary non-woven fabric manufactured exhibits the softness and good texture brought by the hot air non-woven fabric, and exhibits durable strength.

[0188] The conveying speed of the fiber web in the hot air step is preferably 3 m / min or more, more preferably 10 m / min or more, and is preferably 200 m / min or less, more preferably 160 m / min or less within the above-mentioned temperature and wind speed ranges.

[0189] The fiber aggregate obtained through the above steps has been converted into a nonwoven fabric, and thus can be used directly as the sanitary nonwoven fabric of the present invention. The sanitary nonwoven fabric is a hot air nonwoven fabric.

[0190] From the viewpoint of easily obtaining a sanitary nonwoven fabric having a predetermined volume filling rate, it is preferred to further subject the fiber assembly obtained through the above steps to a densification treatment (densification step). The densification treatment in this step can be performed by a method that compresses the fiber assembly in its thickness direction.

[0191] The densification treatment may be performed, for example, by placing the fiber assembly between two metal plates and applying pressure (hereinafter, this method is also referred to as a "pressing method"), or by introducing the fiber assembly between a pair of rollers and applying pressure (hereinafter, this method is also referred to as a "calendering method").

[0192] The compaction treatment may be performed only once, or may be performed multiple times by the same or different methods as required. In addition, the temperature during the compaction treatment may be room temperature, heated, or a combination of these.

[0193] The conditions for the compaction treatment are preferably pressurized in a heated state. Specifically, from the viewpoint of sufficiently compacting the fiber assembly to easily obtain a sanitary nonwoven fabric with a high volume filling rate, when a pressing method is used, the pressurization conditions in the compaction treatment are expressed as a surface pressure of preferably 5 MPa or more, and more preferably 10 MPa or more.

[0194] In addition, from the viewpoint of not membrane-forming the fiber aggregate, maintaining the fiber shape with clear boundaries between the constituent fibers, and making the obtained sanitary nonwoven fabric have a good texture, when using the pressing method, the pressurization conditions in the compaction treatment are expressed in terms of surface pressure, which can be preferably set to less than 72 MPa, and more preferably to less than 32 MPa.

[0195] In addition, from the perspective of fully compacting the fiber aggregate and easily obtaining a sanitary nonwoven fabric with a high volume filling rate, the pressurizing conditions when using the calendering method, expressed in terms of linear pressure, are preferably above 78.4 N / cm (8 kgf / cm), and more preferably above 127.4 N / cm (13 kgf / cm).

[0196] In addition, from the viewpoint of preventing the fiber aggregate from being membrane-formed, maintaining the fiber shape with clear boundaries between the constituent fibers, and making the obtained sanitary nonwoven fabric have a good texture, the pressurizing conditions when using the calendering method are expressed in terms of linear pressure, preferably below 686 N / cm (70 kgf / cm), and more preferably below 294 N / cm (30 kgf / cm).

[0197] In addition, from the perspective of fully compacting the fiber aggregate to easily obtain a sanitary nonwoven fabric with a high volume filling rate, in either the pressing method or the calendering method, the heating temperature in the compaction treatment is preferably above 70°C, and more preferably above 80°C.

[0198] From the viewpoint of preventing the fiber aggregate from being membrane-formed, maintaining the fiber shape with clear boundaries between the constituent fibers, and making the obtained sanitary nonwoven fabric have a good texture, the heating temperature in the compaction treatment can be preferably set to below 120°C, and more preferably to below 110°C, in either the pressing method or the calendering method.

[0199] When heating is performed during the compaction treatment, the metal flat plate may be heated to the above-mentioned temperature range in the case of a pressing method, and the peripheral surface of a roll may be heated to the above-mentioned temperature range in the case of a calendering method.

[0200] The pressing time in the densification treatment can be appropriately set as long as the densification can be performed while maintaining the fiber shape of the fibers constituting the fiber aggregate.

[0201] For example, when a press method is used, the pressurization time under the above-mentioned pressure and temperature conditions can be preferably set to 5 seconds or more, more preferably 10 seconds or more per one compaction treatment.

[0202] When the pressing method is used, the pressing time under the above-mentioned pressure and temperature conditions is preferably set to 25 seconds or less, and more preferably set to 20 seconds or less per one compaction treatment.

[0203] For example, when the calendering method is used, the pressing time under the above-mentioned pressure and temperature conditions can be preferably set to 0.01 seconds or more, and more preferably set to 0.04 seconds or more per one compaction treatment.

[0204] When the calendering method is used, the pressing time under the above-mentioned pressure and temperature conditions can be preferably set to 0.1 seconds or less, and more preferably set to 0.08 seconds or less per one compaction treatment.

[0205] By performing the densification treatment under the above conditions, the fiber aggregate can be compressed in the thickness direction, and a sanitary nonwoven fabric having a predetermined volume filling rate can be easily obtained.

[0206] In particular, within the above-mentioned pressure and temperature range, the constituent resin of the fiber is not easily melted, and the morphological stability and dimensional stability brought about by the heat treatment can be improved, so that a sanitary nonwoven fabric that maintains a specified volume filling rate even after production can be obtained.

[0207] Furthermore, when using fibers having a perfect circular cross-sectional shape, the cross-sectional shape of the fibers can be flattened by a densification treatment, which also has the advantage of being able to increase the volume filling rate.

[0208] The sanitary nonwoven fabric obtained by the above method is an air-through nonwoven fabric even when subjected to a densification treatment.

[0209] The sanitary nonwoven fabric of the present invention can also be produced by a method based on a spunbond method instead of the above-mentioned production method. The sanitary nonwoven fabric produced in this way is a spunbond nonwoven fabric.

[0210] Specifically, the raw material resin of the fiber is extruded in a molten state from a spinning head having a plurality of fine holes, and the extruded resin is stretched by a roller or the like to form long fibers, and these long fibers are gathered on a mesh conveyor belt to obtain a web of fibers having at least a portion of the surface containing a polyethylene resin. Thereafter, the fiber web is introduced between embossing rollers, and compacted (thermocompression bonding) is performed by heating and pressurizing to obtain the sanitary nonwoven fabric of the present invention. That is, the present method is a method of simultaneously performing nonwoven fabrication and compaction treatment of the fiber web. The temperature and pressurization conditions of the embossing rollers can be set in the same range as the conditions for the above-mentioned compaction treatment.

[0211] In the case of manufacturing a multi-layered nonwoven fabric, for example, a second fiber web containing a thermoplastic resin formed by a carding method is laminated on a fiber web containing a polyethylene resin at least partially on the surface to form a laminate of fiber webs. Then, the laminate is subjected to a hot air treatment to obtain a hot air nonwoven fabric as a fiber assembly of a multi-layered structure. At this time, the temperature of the hot air blown is preferably determined by setting the melting point of the resin with the lowest melting point to the above-mentioned melting point M.

[0212] Another method of producing a multilayered sanitary nonwoven fabric is to obtain the nonwoven fabric by subjecting a fiber web having at least a portion of its surface made of a polyethylene resin and a second fiber web made of a thermoplastic resin to hot air treatment to obtain fiber sheets, and then joining the fiber sheets with an adhesive.

[0213] The fiber assembly obtained through the above steps can be used directly as the sanitary nonwoven fabric of the present invention. In addition, a densification step may be performed under the above conditions.

[0214] Alternatively, the target nonwoven fabric can also be manufactured by a method based on a spunbond method. As a manufacturing method, for example, the second fiber web is laminated on a fiber web containing a polyethylene resin at least partially on the surface, and in this state, it is compacted (thermocompression bonded) by heating and pressurizing. The sanitary nonwoven fabric manufactured in this way is a spunbond nonwoven fabric.

[0215] The sanitary nonwoven fabric of the present invention can be obtained through the above steps. The sanitary nonwoven fabric is preferably incorporated as a component of sanitary products such as absorbent articles in the subsequent steps.

[0216] When sanitary nonwoven fabric is used as a constituent material of sanitary products such as absorbent articles, any process of manufacturing sanitary products may include one or more of the following processes to manufacture the target absorbent articles or other sanitary products: a process of using the sanitary nonwoven fabric manufactured by the above method as one of the constituent materials and cutting the sanitary nonwoven fabric; a process of performing various operations such as laminating or joining the sanitary nonwoven fabric with other constituent materials (such as absorbent bodies or sheets, etc.) constituting the sanitary products.

[0217] When manufacturing a sanitary article having a second member, for example, after separately manufacturing the sanitary nonwoven fabric, at any stage of the manufacturing process of the sanitary article, the sanitary nonwoven fabric as the first fiber assembly and the absorbent body or absorbent sheet as the second member are stacked or joined in an adjacent state. In this case, the sanitary nonwoven fabric may be arranged in a manner constituting a surface facing the skin of the wearer when the sanitary article is worn, or may be arranged on a surface side that does not face the skin of the wearer when the sanitary article is worn.

[0218] As mentioned above, although this invention was demonstrated based on the preferred embodiment of this invention, this invention is not limited to the said embodiment.

[0219] The embodiments of the present invention described above further disclose the following sanitary nonwoven fabric, an absorbent article including the same, and a method for producing the sanitary nonwoven fabric.

[0220] <1>

[0221] A sanitary nonwoven fabric comprising fibers at least a portion of the surface of which contains a polyethylene resin, and

[0222] The volume filling rate is 3.5% or more, more preferably 7% or more, further preferably 10% or more, and still more preferably 14% or more.

[0223] <2>

[0224] A sanitary nonwoven fabric, comprising fibers having a thermal conductivity of 0.11 W / mK or more, more preferably 0.13 W / mK or more, and further preferably 0.15 W / mK or more, on at least a portion of its surface, and

[0225] The volume filling rate is 3.5% or more, more preferably 7% or more, and further preferably 14% or more.

[0226] <3>

[0227] The sanitary nonwoven fabric as described in <1> or <2> above, wherein the volume filling factor is 60% or less, preferably 50% or less, and more preferably 30% or less.

[0228] <4>

[0229] A sanitary nonwoven fabric as described in any one of <1> to <3> above, wherein the fiber is (i) a bicomponent composite fiber containing a polyethylene resin both on the outer surface and inside of the fiber, or (ii) a bicomponent 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 in at least a portion of the fiber surface along the length direction.

[0230] <5>

[0231] The sanitary nonwoven fabric as described in any one of <1> to <4> above, 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, relative to the total mass of the resin contained in the sanitary nonwoven fabric.

[0232] <6>

[0233] The sanitary nonwoven fabric as described in any one of <1> to <5> above, wherein the resin constituting the fibers is only polyethylene resin.

[0234] <7>

[0235] The sanitary nonwoven fabric as described in any one of <1> to <6> above, wherein the cross-sectional shape of the fiber has a major axis and a minor axis, and

[0236] 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.

[0237] <8>

[0238] The sanitary nonwoven fabric as described in any one of <1> to <7>, wherein the fibers are in contact with each other at multiple points in cross-sectional view.

[0239] <9>

[0240] The sanitary nonwoven fabric as described in any one of <1> to <8> above, wherein 4.9 mN / cm 2 The thickness under load is 0.1 mm or more and 3 mm or less.

[0241] <10>

[0242] The sanitary nonwoven fabric as described in any one of <1> to <9> above, wherein 4.9 mN / cm 2 The thickness under load is 0.3 mm or more and 0.5 mm or less.

[0243] <11>

[0244] The sanitary nonwoven fabric as described in any one of <1> to <10> above, having a weight per unit area of ​​15 g / m 2 Above and 140g / m 2 the following.

[0245] <12>

[0246] The sanitary nonwoven fabric as described in any one of <1> to <11> above, having a weight per unit area of ​​25 g / m 2 Above and 50g / m 2 the following.

[0247] <13>

[0248] The sanitary nonwoven fabric as described in any one of <1> to <12>, wherein the polyethylene resin comprises a high-density polyethylene resin, and preferably comprises only a high-density polyethylene resin.

[0249] <14>

[0250] The sanitary nonwoven fabric as described in any one of <1> to <13>, wherein the fiber diameter of the fiber is 3 μm or more, preferably 5 μm or more.

[0251] <15>

[0252] The sanitary nonwoven fabric as described in any one of <1> to <14>, wherein the fiber diameter of the fiber is 70 μm or less, preferably 50 μm or less.

[0253] <16>

[0254] The sanitary nonwoven fabric as described in any one of <1> to <15> above, which is an air-through nonwoven fabric.

[0255] <17>

[0256] A sanitary product comprising the sanitary nonwoven fabric as described in any one of <1> to <16> above.

[0257] <18>

[0258] The sanitary product as described in the above-mentioned <17>, wherein the sanitary nonwoven fabric constitutes a surface of the sanitary product facing the skin of the wearer.

[0259] <19>

[0260] The sanitary article as described in the above <17> or <18>, which is an absorbent article.

[0261] <20>

[0262] The sanitary article as described in any one of <17> to <19>, wherein the sanitary nonwoven fabric is disposed on an outer surface of the sanitary article.

[0263] <21>

[0264] The sanitary nonwoven fabric or sanitary article as described in any one of <1> to <20> above, which is disposable.

[0265] <22>

[0266] A method for producing a sanitary nonwoven fabric comprises subjecting a web of fibers having at least a portion of its surface containing a polyethylene resin to a hot air treatment to obtain a fiber aggregate, and then,

[0267] The fiber aggregate is subjected to a compression treatment.

[0268] <23>

[0269] The method for producing a sanitary nonwoven fabric as described in <22> above, wherein the densification treatment is carried out at a surface pressure of 5 MPa or more, preferably 10 MPa or more, or at a linear pressure of 78.4 N / cm (8 kgf / cm) or more, preferably 127.4 N / cm (13 kgf / cm) or more, and

[0270] The reaction is performed at a temperature of 70°C to 120°C.

[0271] <24>

[0272] A method for producing a sanitary nonwoven fabric as described in <22> or <23> above, wherein the above-mentioned compaction treatment is carried out under a surface pressure of less than 30 MPa, preferably less than 20 MPa, or under a linear pressure of less than 686 N / cm (70 kgf / cm), preferably less than 294 N / cm (30 kgf / cm).

[0273] <25>

[0274] The method for producing a sanitary nonwoven fabric according to any one of <22> to <24>, wherein the densification treatment is performed at a temperature of 80° C. to 110° C.

[0275] <26>

[0276] A method for producing a sanitary nonwoven fabric as described in any one of items <22> to <25> above, wherein the hot air treatment is carried out by blowing hot air having a temperature of not less than -4°C the melting point of the resin constituting the fiber surface and not more than +4°C the melting point of the resin onto the web at a wind speed of not less than 0.6 m / s and not more than 2 m / s.

[0277] <27>

[0278] The method for producing a sanitary nonwoven fabric as described in any one of <22> to <26>, wherein the hot air treatment is more preferably performed by blowing hot air having a temperature of not less than -2°C the melting point of the resin constituting the fiber surface and not more than +2°C the melting point to the web.

[0279] <28>

[0280] The method for producing a sanitary nonwoven fabric as described in any one of <22> to <27>, wherein the surface of the fiber contains a high-density polyethylene resin,

[0281] The melting point of the high-density polyethylene resin is 130°C, and

[0282] The hot air treatment is performed by blowing hot air having a temperature of 126° C. or higher, preferably 128° C. or higher, and more preferably 130° C. or higher, to the web.

[0283] <29>

[0284] The method for producing a sanitary nonwoven fabric as described in any one of <22> to <28>, wherein the surface of the fiber contains a high-density polyethylene resin,

[0285] The melting point of the high-density polyethylene resin is 130°C, and

[0286] The hot air treatment is performed by blowing hot air having a temperature of 134° C. or lower, preferably 133° C. or lower, and more preferably 132° C. or lower, to the web.

[0287] <30>

[0288] The method for producing a sanitary nonwoven fabric according to any one of <22> to <29>, wherein the hot air treatment is performed by blowing hot air onto the web at a wind speed of 1 m / sec to 1.4 m / sec.

[0289] <31>

[0290] A method for manufacturing a sanitary product, which comprises one or more of the following steps in any process of manufacturing the sanitary product: a step of using a sanitary nonwoven fabric manufactured by the method for manufacturing a sanitary nonwoven fabric as described in any one of items <22> to <30> as one of the constituent materials and cutting the sanitary nonwoven fabric; and a step of laminating or joining the sanitary nonwoven fabric with other constituent materials constituting the sanitary product.

[0291] <32>

[0292] The sanitary nonwoven fabric as described in any one of <1> to <16> has a cool touch feeling q max 0.06W / m 2 above.

[0293] <33>

[0294] The sanitary nonwoven fabric as described in any one of <1> to <16> and <32>, wherein the constituent fibers are present in a ratio of 40% or more by area on the surface of the sanitary nonwoven fabric.

[0295] <34>

[0296] The sanitary nonwoven fabric as described in any one of <1> to <16>, <32>, and <33>, wherein the volume filling factor is 10.0% or more.

[0297] <35>

[0298] A sanitary product comprising the sanitary nonwoven fabric as described in any one of <1> to <16> and <32> to <34>, and a second member disposed adjacent to the nonwoven fabric, and

[0299] The second component is 9.8mN / cm 2 (1gf / cm 2 ) The compression deformation under load is greater than 0.3 mm.

[0300] <36>

[0301] The sanitary article as described in the above-mentioned <35>, wherein the second member is a fiber aggregate different from the sanitary nonwoven fabric.

[0302] <37>

[0303] The sanitary product as described in the above-mentioned <36>, wherein the second member is an absorbent body.

[0304] <38>

[0305] A method for producing a sanitary nonwoven fabric, which is a method for producing a sanitary nonwoven fabric as described in any one of <1> to <16> and <32> to <34> above, and

[0306] A fiber aggregate is obtained by subjecting a web of fibers having at least a portion of its surface containing a polyethylene resin to a hot air treatment, and then,

[0307] The fiber aggregate is subjected to a compression treatment.

[0308] Example

[0309] Hereinafter, the present invention will be described in more detail by way of examples, but the scope of the present invention is not limited to these examples.

[0310] [Examples 1 to 5]

[0311] Fibers containing a single resin, HDPE, and having a flat and multi-lobed cross-sectional shape having a major axis and a minor axis (hereinafter, this shape is also referred to as a "flat profile", and the same applies to the table) were used. The major axis length, minor axis length, and the ratio of the major axis length to the minor axis length (this ratio is also referred to as a "major axis / minor axis ratio" in the table) in the fiber cross section are shown in the following Table 1.

[0312] First, a web of the above-mentioned fibers whose weight per unit area is adjusted as shown in Table 1 below is subjected to hot air treatment to obtain a fiber assembly of nonwoven fabric. The conditions of the hot air treatment are shown in Table 1 below. Then, the fiber assembly is subjected to compaction treatment by a pressing method under the heating and pressurizing conditions shown in Table 1 below to obtain the target sanitary nonwoven fabric. The obtained nonwoven fabrics are all single-layer.

[0313] [Examples 6 to 8]

[0314] The target sanitary nonwoven fabrics were obtained in the same manner as in Examples 1 to 5 except that the weight per unit area was adjusted as shown in Table 1 below and the densification treatment was performed by calendering under the heating and pressurizing conditions shown in Table 1 below. The obtained nonwoven fabrics were all single-layer.

[0315] [Example 9]

[0316] A core-sheath fiber (hereinafter referred to as PET / HDPE fiber) having a perfect circular cross-sectional shape and a core of PET and a sheath (fiber surface) of HDPE was used. The polyethylene resin content of the fiber was 50% by mass. Under the same conditions as in Example 1, a fiber web containing the fiber was subjected to hot air treatment and compaction treatment to obtain a target sanitary nonwoven fabric. The obtained nonwoven fabric was a single layer.

[0317] [Example 10]

[0318] Fibers containing a single resin, HDPE, and having a perfect circular cross-sectional shape were used. A web of the above fibers whose unit weight was adjusted as shown in Table 1 below was produced by a spunbond method, and the web was compacted by an embossing roll to obtain a sanitary nonwoven fabric consisting of a spunbond nonwoven fabric. The conditions of the spunbond method are shown in Table 1 below. The obtained nonwoven fabric was a single layer.

[0319] [Example 11]

[0320] The target sanitary nonwoven fabric was obtained in the same manner as in Example 1 except that the densification treatment was not performed.

[0321] [Examples 12 to 14]

[0322] A core-sheath fiber (hereinafter referred to as PP / HDPE fiber) having a perfect circular cross-sectional shape and a core of PP and a sheath (fiber surface) of HDPE was used. The polyethylene resin content of the fiber was 50% by mass. A web of the above-mentioned fibers whose unit area weight was adjusted to be as shown in Table 1 below was formed, and the web was subjected to hot air treatment and compaction treatment under the same conditions as in Example 1 to obtain the target sanitary nonwoven fabric. The obtained nonwoven fabrics were all single-layer.

[0323] [Comparative Example 1]

[0324] A fiber web was formed using the same core-sheath fibers as in Example 9 and subjected to hot air treatment under the conditions shown in the following Table 1 to obtain the intended sanitary nonwoven fabric. In this comparative example, no densification treatment was performed.

[0325] [Comparative Example 2]

[0326] A fiber web was formed using the same core-sheath fibers as in Example 12, and hot air treatment was performed under the conditions shown in the following Table 1 to obtain the target sanitary nonwoven fabric. In this comparative example, no densification treatment was performed.

[0327] [Comparative Example 3]

[0328] A fiber web 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. Thereafter, the web was subjected to a densification treatment by calendering without heating under the conditions shown in Table 1 below to obtain a target sanitary nonwoven fabric.

[0329] [Measurement of Thickness of Sanitary Nonwoven Fabrics]

[0330] The thickness of the sanitary nonwoven fabrics of the examples and comparative examples was measured. In the thickness measurement, a 4.9 mN / cm 2 The laser displacement meter was used to measure at 5 or more locations under load, and the arithmetic mean of the measured values ​​was defined as the thickness (mm).

[0331] [Measurement of thermal conductivity of nonwoven fabrics]

[0332] The thermal conductivity of the sanitary nonwoven fabrics of Examples and Comparative Examples was measured by the following method.

[0333] (1. Sample production)

[0334] The sanitary nonwoven fabric to be measured was cut into small pieces, and a laminate of about 10 g formed by stacking multiple pieces was held between two SUS plates and placed in the center of the SUS plates, and heated for 1 minute without pressurization to obtain a fused product. The heating temperature was the melting point M+20°C measured by the above-mentioned differential scanning calorimeter. In the case of a nonwoven fabric containing multiple resin materials, the heating was performed based on the melting point of the resin with the highest melting point. Specifically, the nonwoven fabric containing pure HDPE fibers was heated at 50°C, the nonwoven fabric containing PP / HDPE fibers was heated at 180°C, and the nonwoven fabric containing PET / HDPE fibers was heated at 300°C.

[0335] Then, while maintaining the above-mentioned heating temperature, a gauge pressure of 200kgf (total mass including the top plate: 21848kg; when calculating the pressure based on the surface pressure, the area of ​​the melt will change as the resin melts, so the surface pressure should be calculated based on the area of ​​the circular resin plate finally obtained. For example, when the diameter of the circular resin plate is 15cm, the surface pressure is 12MPa) is applied to the obtained melt and maintained for 1 minute. Then, the melt is water-cooled to 20°C while maintaining the pressurized state to obtain a circular resin plate with a diameter of about 15 to 20cm (the diameter of the obtained circular resin plate may vary depending on the melt viscosity of the resin).

[0336] Then, the obtained circular resin plate is cut in a radial shape through the center. In addition, if the maximum diameter is more than 5cm, it is further cut into less than 5cm. Then, the cut resin plate is overlapped and placed in the center of the SUS plate in a random manner to eliminate the influence of resin orientation so that the extension direction of the imaginary line segment of the maximum diameter is random. Two shims with a thickness of 1mm are arranged in parallel at a position 10cm from the center of the SUS plate, and the SUS plate is overlapped thereon. Thereafter, by the same operation as above, heating under non-pressurized conditions and heating and cooling under pressurized conditions are performed. In the case of bubbles entering, the same action is repeated. The purpose of the 2nd heating and melting is to temporarily melt the sample, eliminate the influence of the crystallization of the resin that changes in the fiber spinning process, and make the thermal history certain. Thus, a film is obtained.

[0337] (2. Determination of thermal conductivity)

[0338] The thermal conductivity was measured by the following method using a measuring device (KES-F7 Thermo Lab II manufactured by Kado Techno Co., Ltd.).

[0339] First, a circle with a diameter of 17 cm was cut out from the prepared film and placed in an environment with a room temperature of 23°C and a relative humidity of 50% for 24 hours. Then, the thermal conductivity of the object to be measured was measured using the above-mentioned measuring device and in accordance with the measuring guide of the device. Specifically, the temperature of the heat source body (BT-BOX, which is an integrated aluminum plate with a length of 5 cm × a width of 5 cm and a thickness of 1 mm and a heater, etc.) used for measurement was set to 33°C (a temperature 10°C higher than the surface temperature of the object to be measured). In order to prevent the film from warping and causing a reduction in the contact area, the film was heated every 0.25 m. 2 The heat source is brought into contact with the film by applying a load of 1 kg to an area of ​​the film. In the display panel of the measuring device, the time point when the heat flow from the heat source to the measured object becomes constant is set as the measurement start time point, and the average heat flow within 60 seconds from this time point is measured. According to the measurement conditions and the heat flow obtained by the measurement, it is calculated based on the following formula (I). The thickness D of the film is the arithmetic mean of the thickness obtained by measuring more than 3 parts under no-load conditions by a laser displacement meter. The above measurement is performed 3 times for each measured object, and the maximum value of the obtained measured values ​​is set as the thermal conductivity (W / mK) of the sample. The results are shown in Table 1.

[0340] As reference examples, the thickness D and thermal conductivity of a film produced by the above method using only PET and a film produced by the above method using only PP were measured. The results are shown in Table 2 together with the results of Examples and Comparative Examples.

[0341] k=100×(W×D) / (A×ΔT)…(I)

[0342] (k: thermal conductivity [W / mK], W: heat flow [W / m 2 ], D: film thickness [cm], A: aluminum plate area (25cm 2 ), ΔT: Temperature difference between heat source and film (10°C)

[0343] [Measurement of volume filling rate]

[0344] The volume filling ratio (%) of the sanitary nonwoven fabrics of Examples and Comparative Examples was calculated by the above-mentioned method. The results are shown in Table 1.

[0345] [Contact cool feeling max Determination of

[0346] A hot plate such as a metal plate with a temperature sensor is made to store heat and the temperature of the hot plate is set to a higher temperature than the object to be measured. The hot plate is brought into contact with the surface of the object to be measured. After the contact, the heat stored on the hot plate is immediately transferred to the object to be measured at the low temperature side. The maximum value of the heat flow at this time is the contact cooling sensation q. max .

[0347] Cool touch max The measurement was performed by the following method using a measuring apparatus (KES-F7 Thermo LabII manufactured by Kado Techno Co., Ltd.).

[0348] First, a test piece having a size of 10 cm in length×10 cm in width was cut out from a sanitary nonwoven fabric to be measured, and the test piece was left to stand in an environment of room temperature 23° C. and relative humidity 50% for 24 hours.

[0349] Then, under this environment, the test piece is placed on the measuring table and fixed to the measuring table using double-sided tape. A constant temperature device using gas or liquid as a heat medium is used as the measuring table.

[0350] Then, the contact coolness q of the measurement object is measured by the above-mentioned measurement device and according to the measurement guide of the device. max Specifically, the area used is 9.0 cm 2 , a pure copper plate of mass 9.8g is used as a hot plate in contact with the object to be measured, the initial temperature of the copper plate is set to 33°C (a temperature 10°C higher than the surface temperature of the object to be measured), the contact pressure between the copper plate and the object to be measured is set to 1kPa, the copper plate is brought into contact with the test piece, the value of the heat flow at the moment of contact is set to zero, and the maximum value of the heat flow is measured. This measurement is performed 5 times for each surface of the object to be measured, and the arithmetic average of the obtained multiple measurement values ​​is set as the contact coolness q of the object to be measured max (W / m 2 ).

[0351] Cool touch max The larger the value of , the faster the heat transfer is, and the easier it is for the user to feel a cool sensation. The results are shown in Table 1 below.

[0352] [Table 1]

[0353]

[0354] [Table 2]

[0355]

[0356] As shown in Table 1 and Table 2, it can be seen that the sanitary nonwoven fabrics of each embodiment have higher thermal conductivity and volume filling rate than the comparative example. max Also high.

[0357] In particular, it can be seen from Examples 1 to 8 that this effect becomes remarkable by using flat and irregular-shaped fibers.

[0358] Therefore, when the sanitary nonwoven fabric of the present invention comes into contact with the user's skin, the user can feel a cool sensation, thereby providing a comfortable feeling of use.

[0359] [Examples 15 and 16]

[0360] The hot air nonwoven fabric containing a single resin HDPE used in Example 2 was set as the first fiber layer, and the single-layer hot air nonwoven fabric containing PET / HDPE fibers whose unit weight was adjusted as shown in Table 3 below was set as the second fiber layer. These fiber layers were stacked 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 configuration of the first fiber layer in this example is the same as that of the sanitary nonwoven fabric in Example 2.

[0361] [Examples 17 to 21]

[0362] The hot air nonwoven fabric containing a single resin HDPE used in Example 4 was set as the first fiber layer, and the single-layer hot air nonwoven fabric containing PET / HDPE fibers whose unit weight was adjusted as shown in Table 3 below was set as the second fiber layer. These fiber layers were stacked 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 configuration of the first fiber layer in this example is the same as that of the sanitary nonwoven fabric in Example 4.

[0363] [Example 22]

[0364] The hot air nonwoven fabric containing a single resin HDPE used in Example 10 was set as the first fiber layer, and the single-layer hot air nonwoven fabric containing PET / HDPE fibers whose unit weight was adjusted as shown in Table 3 below was set as the second fiber layer. These fiber layers were stacked 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 configuration of the first fiber layer in this example is the same as that of the sanitary nonwoven fabric in Example 10.

[0365] [Measurement of volume filling rate]

[0366] The volume filling ratio (%) of the sanitary nonwoven fabric of the examples 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 fabrics in Examples 2, 4, and 10 are shown again.

[0367] [Contact cool feeling max Determination of

[0368] The cool feeling q of the sanitary nonwoven fabric of the example was measured in the same manner as the above method. max For Examples 15 to 22, the surface on which the first fiber layer was disposed was measured. The results are shown in Table 3.

[0369] [Sensory evaluation of cooling sensation]

[0370] 20 professional sensory inspectors were asked to touch the sanitary nonwoven fabrics of Examples 2, 4, and 10, and the surface of the first fiber layer in the sanitary nonwoven fabrics of Examples 15 to 22, and evaluate the cool feeling felt when touching the surface according to the following criteria. It should be noted that the sanitary nonwoven fabrics used for evaluation were placed in an environment of 23°C and became isothermal with the ambient temperature. The higher the arithmetic mean of the evaluation score, the easier it is to effectively feel the cool feeling of the sanitary nonwoven fabric. The results are shown in Table 3 below.

[0371] 5 points: with q max The fiber sheet with a value of 0.15 or more can provide a similarly strong cooling feeling, and the cooling feeling is very excellent.

[0372] 4 points: A good cooling sensation can be felt.

[0373] 3 points: A cool feeling can be felt.

[0374] 2 points: Almost no cooling sensation is felt.

[0375] 1 point: with q max The air-through nonwoven fabric with a value less than 0.06 does not feel cool at all to the same extent.

[0376] [Table 3]

[0377]

[0378] As shown in Table 3, it can be seen that the volume filling rate and the contact coolness q of the sanitary nonwoven fabrics of each embodiment are max Both are high, giving people an excellent cooling feeling.

[0379] In addition, the fiber surface existence ratio (%) of the sanitary nonwoven fabrics of Example 9 and Comparative Example 1 was calculated by the above-mentioned method.

[0380] As a result, the fiber surface existence rate of Example 9 was 58%, and the fiber surface existence rate of Comparative Example 1 was 36%. Therefore, the fiber surface existence rate of Example 9 was higher than that of Comparative Example 1, and the contact property of the fiber with respect to the contact object could be further improved. As a result, an excellent cooling sensation could be felt.

[0381] Industrial Applicability

[0382] According to the present invention, there are provided a sanitary nonwoven fabric which gives a cool feeling when in contact with the skin and provides a comfortable feeling of use, and a sanitary product and an absorbent article having the same.

Claims

1. An absorbent article comprising a sanitary nonwoven fabric, The sanitary nonwoven fabric comprises fibers whose surface at least partly comprises polyethylene resin and whose surface at least partly has a thermal conductivity of 0.11 W / mK or more. The volume filling rate of the sanitary nonwoven fabric is 14.0% or more, The fiber diameter of the fiber used in the sanitary nonwoven fabric is 5 μm or more and 50 μm or less. 4.9 mN / cm 2 The thickness under load is 0.2 mm or more and 0.5 mm or less, The weight per unit area of ​​the sanitary nonwoven fabric is 25 g / m 2 Above and 90 g / m 2 the following, The cool feeling of the sanitary nonwoven fabric max 0.22 W / m 2 above, The sanitary nonwoven fabric is a hot air nonwoven fabric. The sanitary nonwoven fabric is used as a front sheet, a side nonwoven fabric, waist gathers, gathers arranged near the groin, or a constituent member of an outer packaging body.

2. The absorbent article according to claim 1, wherein The cross-sectional shape of the fiber 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.

3. The absorbent article according to claim 1 or 2, wherein: In cross-sectional view, the fibers are in contact with each other at multiple points.

4. The absorbent article according to claim 1 or 2, wherein: The constituent fibers are present in a ratio of 40% or more on the surface of the sanitary nonwoven fabric in terms of area.

5. The absorbent article according to claim 1 or 2, wherein: The fiber is a fiber whose outer surface and interior both contain polyethylene resin, or The fiber is a composite fiber containing a low melting point component including 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 in at least a portion of the fiber surface in the longitudinal direction.

6. The absorbent article according to claim 1 or 2, wherein: The fibers comprise a polyethylene resin, and The content of the polyethylene resin is 70% by mass or more and 100% by mass or less relative to the total mass of the fiber.

7. The absorbent article according to claim 1 or 2, wherein: The fibers comprise only polyethylene resin.

8. The absorbent article according to claim 1 or 2, wherein: The fibers include high density polyethylene resin.

9. The absorbent article according to claim 1 or 2, wherein: The fibers comprise only high density polyethylene resin.

10. The absorbent article according to claim 1 or 2, further comprising a second member disposed adjacent to the nonwoven fabric, and The second member is at 9.8 mN / cm 2 The compressive deformation under load is 0.3 mm or more.

11. The absorbent article according to claim 10, wherein The second member is a fiber assembly different from the sanitary nonwoven fabric.

12. The absorbent article according to claim 10, wherein The second member is an absorbent body.

13. The absorbent article according to claim 1 or 2, wherein: The sanitary nonwoven fabric is arranged on the outer surface.

14. A method for producing an absorbent article, comprising the following steps: A fiber aggregate is obtained by subjecting a web of fibers having at least a portion of its surface containing a polyethylene resin to a hot air treatment, and then, The fibrous aggregate is subjected to a densification treatment to produce the sanitary nonwoven fabric.

15. The manufacturing method according to claim 14, wherein: The densification treatment is performed at a surface pressure of 5 MPa or more or a linear pressure of 78.4 N / cm or more and at a temperature of 70° C. or more and 120° C. or less.

16. The manufacturing method according to claim 14 or 15, wherein: The hot air treatment is performed by blowing hot air having a temperature of not less than -4°C the melting point of the resin constituting the fiber surface and not more than +4°C the melting point of the resin onto the web at a wind speed of not less than 0.6 m / sec and not more than 2 m / sec.

Images