CN117337346A - Method for producing nonwoven fabric, nonwoven fabric produced by using same, and absorbent article comprising same as constituent member - Google Patents

Method for producing nonwoven fabric, nonwoven fabric produced by using same, and absorbent article comprising same as constituent member Download PDF

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Publication number
CN117337346A
CN117337346A CN202180097455.8A CN202180097455A CN117337346A CN 117337346 A CN117337346 A CN 117337346A CN 202180097455 A CN202180097455 A CN 202180097455A CN 117337346 A CN117337346 A CN 117337346A
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CN
China
Prior art keywords
nonwoven fabric
web
less
producing
fabric according
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Pending
Application number
CN202180097455.8A
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Chinese (zh)
Inventor
凑崎真行
菅原拓也
野田章
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Kao Corp
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Kao Corp
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Publication of CN117337346A publication Critical patent/CN117337346A/en
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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/51—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the outer layers
    • A61F13/511—Topsheet, i.e. the permeable cover or layer facing the skin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4374—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece using different kinds of webs, e.g. by layering webs
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving

Abstract

In the production method of the present invention, hot air is blown to a web containing heat-fusible fibers having a fiber diameter of 15 μm or less under the following conditions to fuse the intersections of the fibers constituting the web. The above production method preferably blows hot air to the web under the following conditions. (1) When the melting point of the resin having the lowest melting point among the resins constituting the heat-fusible fibers is Mp, the temperature T1 of the surface of the web opposite to the surface on which the hot air is blown is not less than Mp and not more than mp+15℃. (2) The temperature T1 is lower than the temperature T2 of the hot air blowing surface of the web, and the difference between the temperature T1 and the temperature T2 is 10 ℃ to 35 ℃. (3) The hot air supply rate is 0.30 m/s to 0.60 m/s.

Description

Method for producing nonwoven fabric, nonwoven fabric produced by using same, and absorbent article comprising same as constituent member
Technical Field
The present invention relates to a method for producing a nonwoven fabric, a nonwoven fabric produced by the method, and an absorbent article comprising the nonwoven fabric as a constituent member.
Background
An absorbent article such as a disposable diaper is constituted by a sheet member made of a fibrous material. As a method for producing the sheet member, a method for producing a nonwoven fabric by blowing hot air to a web formed of fibers is known. For example, patent document 1 discloses a method for producing a nonwoven fabric in which a fiber aggregate including thermally fusible fibers containing a low-melting point component and a high-melting point component is subjected to heat treatment and then immediately subjected to cooling treatment.
Further, the applicant has previously disclosed a method for producing a nonwoven fabric in which a hot air nonwoven fabric is subjected to a multi-stage calendering process so that the long axis direction of the cross section of the fiber deformed into a flat shape is oriented substantially in the plane direction of the nonwoven fabric (patent document 2). In this production method, any one of the calender processes is performed under a predetermined condition using a metal calender roll and a resin roll having a predetermined D hardness.
Further, the applicant has previously disclosed a method of producing a nonwoven fabric having irregularities on the surface by embossing a web containing heat-stretchable fibers after forming a bonded web by blowing hot air to the web (patent document 3).
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 6-158499
Patent document 2: japanese patent laid-open No. 2006-23232365
Patent document 3: japanese patent application laid-open No. 2011-137249
Disclosure of Invention
The present invention relates to a method for producing a nonwoven fabric in which heat is blown to a web containing heat-fusible fibers to fuse intersecting points of the fibers constituting the web.
The fiber diameter of the heat-fusible fiber is preferably 15 μm or less.
The above production method preferably blows hot air to the web under the following conditions.
(1) When the melting point of the resin having the lowest melting point among the resins constituting the heat-fusible fibers is Mp, the temperature T1 of the surface of the web opposite to the surface on which the hot air is blown is not less than Mp and not more than mp+15℃.
(2) The temperature T1 is lower than the temperature T2 of the hot air blowing surface of the web, and the difference between the temperature T1 and the temperature T2 is 10 ℃ to 35 ℃.
(3) The hot air supply rate is 0.30 m/s to 0.60 m/s.
The present invention also relates to a nonwoven fabric produced by the above-described production method.
The present invention also relates to an absorbent article comprising the nonwoven fabric as a constituent member.
Drawings
Fig. 1 is a schematic view showing an apparatus used in the method for producing a nonwoven fabric of the present invention.
Fig. 2 is an enlarged cross-sectional view of the hot air treatment unit shown in fig. 1.
Fig. 3 (a) to (c) are schematic diagrams for explaining a method of measuring the number of fibers that develop fuzzing per unit area in examples.
Detailed Description
In the manufacturing methods described in patent documents 1 to 3, nonwoven fabrics are manufactured by blowing hot air to a web to fuse the intersections of fibers. If the web uses fibers having a small fiber diameter, the web may be nonwoven by blowing hot air, but the strength and the feel of the nonwoven obtained tend to be insufficient, and the smoothness and the touch may be lowered. Patent documents 1 to 3 have not been studied particularly in terms of obtaining a nonwoven fabric having a good touch feeling and strength when using a fiber having a small fiber diameter.
Accordingly, the present invention relates to a method for producing a nonwoven fabric which contains fibers having a small fiber diameter and is excellent in skin touch feeling and strength, a nonwoven fabric produced by the production method, and an absorbent article which contains the nonwoven fabric as a constituent member.
The present invention will be described below based on preferred embodiments thereof. The production method of the present embodiment includes a hot air treatment step of blowing hot air to a web containing heat-fusible fibers to fuse the intersections of the fibers constituting the web. The heat treatment step of the present embodiment is a step of blowing heat to a web that is a precursor of a nonwoven fabric. As a method for producing a nonwoven fabric by blowing hot air into a web, a hot air method in which hot air is passed through a web is known, but in the hot air treatment step of the present embodiment, the hot air is blown into a web by using the conditions (1) to (3) described below, so that the whole amount of the blown hot air does not pass through the web. Hereinafter, the nonwoven fabric obtained by the hot air treatment step will also be referred to as "1 st nonwoven fabric 14". The nonwoven fabric obtained by subjecting the 1 st nonwoven fabric 14 to the calender step described later is also referred to as "2 nd nonwoven fabric 10". In the manufacturing method of the present embodiment, the 2 nd nonwoven fabric 10 is finally obtained.
The 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 as the object of the production of the present invention may be a nonwoven fabric having a single-layer structure or a nonwoven fabric having a multilayer structure. The following description is about the production of the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 having a multilayer structure, but the description is also applicable to the production of the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 having a single-layer structure.
The 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 each have a 1 st surface and a 2 nd surface located on the opposite side, and have a laminated structure in which a 1 st layer forming the 1 st surface and a 2 nd layer forming the 2 nd surface are laminated. Layer 1 uses the 1 st net 11 described later as a raw material, and layer 2 uses the 2 nd net 12 described later as a raw material. The nonwoven fabrics 10 and 14 according to the present embodiment have the 1 st layer having a smaller average fiber diameter than the 2 nd layer and include fibers having a fiber diameter of 15 μm or less.
The manufacturing method of the present embodiment will be described with reference to fig. 1 and 2. In fig. 1 and 2, symbol X indicates a conveying direction of the forming material of the nonwoven fabrics 14, 10 such as the conveying webs 11, 12, 13. Fig. 1 shows an embodiment of a manufacturing apparatus used in the method for manufacturing a nonwoven fabric according to the present invention. The manufacturing apparatus 100 shown in fig. 1 includes a web forming section 20, a hot air processing section 30, and a calendaring section 40.
The web forming section 20 includes a 1 st guide 21 and a 2 nd guide 22. The 1 st leader 21 produces a 1 st web 11 corresponding to the 1 st layer. The 2 nd leader 22 is a mechanism for manufacturing the 2 nd wire 12 corresponding to the 2 nd layer. The raw material fibers are supplied from a raw material fiber supply unit (not shown) to the respective guides 21 and 22, and the fibers are carded. Thereby forming the 1 st net 11 and the 2 nd net 12. The 2 nd wire 12 is superimposed on the 1 st wire 11. Thereby forming a laminated web 13 in which webs 11, 12 are laminated. The laminate web 13 is continuously supplied to an air-permeable transport member 31 of the hot air treatment unit 30 described later.
The hot air treatment unit 30 includes a blower 32 that blows hot air to the laminate web 13, a suction box 33 that sucks the hot air, and a conveyor 35 that conveys the laminate web 13. The conveyor 35 includes a breathable conveying member 31 made of a breathable material such as a metal mesh (steel wire mesh or the like), and conveying rollers 34a, 34b, 34c, 34d that bridge the breathable conveying member 31. The air-permeable conveying member 31 is an endless belt. The conveyor 35 is a conveyor belt in which the endless belt circulates in one direction.
The blower 32 and the suction box 33 are disposed to face each other with the air-permeable transport member 31 interposed therebetween. The air-permeable transport member 31 transports the laminated web 13 between the blower 32 and the suction box 33. The blower 32 has a hot air supply port (not shown) for supplying hot air to the air-permeable transport member 31 disposed opposite thereto. The laminated web 13 placed on the air-permeable transport member 31 is transported in the transport direction X and passes under the blower 32. The laminated web 13 passes under the blower 32 in a state where the 2 nd web 12 faces the blower 32 and the 1 st web 11 faces the air-permeable transport member 31. At this time, hot air heated to a predetermined temperature is blown onto the laminate web 13. That is, the surface on the 2 nd wire 12 side of the laminated web 13 becomes a blowing surface of hot air (hereinafter, simply referred to as "blowing surface"), and the surface on the 1 st wire 11 side becomes a non-blowing surface of hot air (hereinafter, simply referred to as "non-blowing surface"). The non-blowing face is the face on the opposite side of the blowing face. The heat-fusible fibers contained in the laminate web 13 are softened or melted by heat applied when the hot air is blown, and the fibers are bonded at the intersections. Thereby, the 1 st nonwoven fabric 14 was obtained. The hot air blown to the laminate web 13 is sucked and recovered by the suction box 33.
In the conveying device 35, the 1 st conveying roller 34a and the 4 th conveying roller 34d are disposed on the upstream side of the conveying path of the laminated web 13 between the blower 32 and the suction box 33, and the 2 nd conveying roller 34b and the 3 rd conveying roller 34c are disposed on the downstream side of the conveying path. The 1 st conveying roller 34a and the 4 th conveying roller 34d are located on the upstream side with respect to the blower 32. The 1 st conveying roller 34a is disposed at a position closer to the blower 32 than the 4 th conveying roller 34d in the vertical direction. The 2 nd conveying roller 34b and the 3 rd conveying roller 34c are located on the downstream side with respect to the blower 32. The 2 nd conveying roller 34b is disposed at a position closer to the blower 32 than the 3 rd conveying roller 34c in the vertical direction.
The manufacturing apparatus 100 includes a cooling device 50 that cools the air-permeable transport member 31 heated by hot air. The cooling device 50 is located between the 3 rd conveying roller 34c and the 4 th conveying roller 34d, and cools the air-permeable conveying member 31 conveyed between these conveying rollers 34c and 34 d. As the cooling device 50, a known device such as a blower fan that blows cold air may be used. As the cooling device 50, any one of the conveying rollers 34a, 34b, 34c, 34d may be used as a cooling roller. The cooling roller is provided with a refrigerant such as water or gas inside.
The calender 40 includes a calender roll 41 made of metal on the surface thereof, and a 1 st resin roll 42 and a 2 nd resin roll 43 made of resin on the surface thereof. The 1 st resin roll 42, the calender roll 41, and the 2 nd resin roll 43 are arranged in this order so as to overlap in the vertical direction. That is, the 1 st resin roll 42 and the 2 nd resin roll 43 are disposed so as to face each other in contact with the calender roll 41. The 1 st resin roll 42 is disposed on the upstream side and the 2 nd resin roll 43 is disposed on the downstream side in the conveyance direction X of the 1 st nonwoven fabric 14. In a state where the 1 st nonwoven fabric 14 is introduced into the calender part 40, the 1 st layer of the 1 st nonwoven fabric 14 is in contact with the calender roll 41 between the 1 st resin roll 42 and the calender roll 41. Further, between the 2 nd resin roll 43 and the calender roll 41, the 1 st layer of the 1 st nonwoven fabric 14 is in contact with the calender roll 41. The 2 nd nonwoven fabric 10 was obtained by the calendering process in the calender part 40. The metal calender roll 41 and the 1 st and 2 nd resin rolls 42 and 43 each have at least a shaft portion made of metal.
In the manufacturing method of the present embodiment, the 2 nd nonwoven fabric 10 is manufactured using the manufacturing apparatus 100 described above. The manufacturing method of the present embodiment includes: a web forming step of forming a 1 st web 11 and a 2 nd web 12, and laminating the two webs 11 and 12 to obtain a laminated web 13; a hot air treatment step of blowing hot air to the laminate web 13 under the conditions (1) to (3) described below to obtain a 1 st nonwoven fabric 14; and a calendaring step of calendaring the 1 st nonwoven fabric 14 to obtain a 2 nd nonwoven fabric 10.
In the web forming step, first, the 1 st web 11 and the 2 nd web 12 are manufactured. These webs 11 and 12 are produced by opening raw material fibers such as heat-fusible fibers with an opener, and forming the opened raw material fibers into webs with the above-mentioned guides 21 and 22. The 1 st and 2 nd webs 11 and 12 are sheets of a stage before the nonwoven fabric is produced, and thermal fusion does not occur between fibers in the webs.
The 1 st and 2 nd nets 11 and 12 contain heat-fusible fibers. The heat-fusible fibers are fibers fused to each other by heat, and are produced from a thermoplastic resin as a raw material. Examples of the thermoplastic resin include polyolefin such as Polyethylene (PE) and polypropylene (PP); polyesters such as polyethylene terephthalate (PET); polyamides such as nylon 6 and nylon 66; the polyalkyl acrylate, polyalkyl methacrylate, polyvinyl chloride, polyvinylidene chloride, etc., may be used singly or in combination of two or more. As the heat-fusible fiber, a composite fiber containing 2 or more components including a low-melting component and a high-melting component can be used. Examples of the composite fiber include a core-sheath type fiber having a core-sheath structure including a core portion and a sheath portion, and a side-by-side fiber. The core-sheath type composite fiber may be concentric or eccentric.
From the viewpoint of ensuring the strength of the nonwoven fabrics 10, 14 more reliably, the heat-fusible fibers preferably contain PE as a constituent resin, more preferably contain PE at least on the surface, and still more preferably are formed of PE. For example, when a fiber having a core-sheath structure is included as the heat-fusible fiber, it is preferable that the resin component of the core portion is PET and the resin component of the sheath portion is PE.
From the same viewpoints as described above, the content of the heat-fusible fibers in the 1 st web 11 is preferably at least 50 mass% or more, more preferably 90 mass% or more and 100 mass% or less with respect to the total mass of the 1 st web 11.
The content of the heat-fusible fibers in the 2 nd web 12 is preferably in the same range as that of the 1 st web 11.
The 1 st and 2 nd webs 11 and 12 may contain other fibers in addition to the heat-fusible fibers. As the other fibers, fibers that are not fused to each other by heat may be mentioned. Examples thereof include pulp, cotton, rayon, lyocell, and tencel. One or a combination of two or more of them may be used alone.
The 1 st web 11 contains heat-fusible fibers having a fiber diameter of 15 μm or less. Hereinafter, the "heat-fusible fiber having a fiber diameter of 15 μm or less" will also be referred to as a fine fiber. The reason why the fine fibers are used as the raw material is to make the surfaces (particularly the surface on the 1 st layer side) of the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 have good touch feeling.
From the viewpoint of further improving the smoothness of the nonwoven fabrics 10, 14, the content of the fine fibers in the 1 st web 11 is preferably 25% or more, more preferably 30% or more, and in practice 100% or less. The content ratio of the fine fibers can be adjusted by using the amount of the raw material fibers used in the production of the 1 st web 11. The method for measuring the content of the fine fibers will be described later.
From the viewpoint of further improving the strength and softness of the nonwoven fabrics 10, 14, it is preferable that the average fiber diameter of the fibers constituting the 2 nd web 12 is larger than the average fiber diameter of the fibers constituting the 1 st web 11 (2 nd web 12 > 1 st web 11).
From the same viewpoints as described above, the difference between the average fiber diameter of the fibers constituting the 1 st web 11 and the average fiber diameter of the fibers constituting the 2 nd web 12 is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 25 μm or less, more preferably 15 μm or less, and further preferably 0.5 μm or more and 25 μm or less, more preferably 1 μm or more and 15 μm or less.
From the viewpoint of further improving the smoothness of the layer 1 side surfaces of the nonwoven fabrics 10, 14, the 1 st web 11 containing fine fibers preferably has an average fiber diameter of 5 μm or more, more preferably 8 μm or more, still more preferably 20 μm or less, still more preferably 15 μm or less, and still more preferably 5 μm or more and 20 μm or less, still more preferably 8 μm or more and 15 μm or less, which constitute the web 11.
From the viewpoint of further improving the touch feeling and strength of the nonwoven fabrics 10, 14, the 2 nd web 12 preferably has an average fiber diameter of the fibers constituting the web 12 of 5 μm or more, more preferably 8 μm or more, still more preferably 30 μm or less, still more preferably 20 μm or less, and yet still more preferably 5 μm or more and 30 μm or less, still more preferably 8 μm or more and 20 μm or less.
The content ratio of the fine fibers, the average fiber diameter of the fibers constituting the 1 st web 11, and the average fiber diameter of the fibers constituting the 2 nd web 12 were measured by observing the respective webs under an electron microscope and observing them under an enlarged scale. Specifically, each net to be measured was cut out in the entire thickness direction using a sharp razor to form a 10mm×30mm region in plan view, and this was used as a measurement sample. A500 μm X400 μm region (observation region) was photographed at a magnification of 200 times on the main surface of the measurement sample using a scanning electron microscope (Scanning Electron Microscope: SEM, JCM-6000Plus trade name, manufactured by Japanese electronics Co., ltd. SEM in the present specification is all the same). In this SEM-based photographing, fibers located at the outermost surface in the photographing field of view of the measurement sample are focused. For 5 sites of 1 piece of measurement sample, the imaging positions of which are different from each other, a total of 5 SEM images were obtained for each surface. For each SEM image obtained, the fiber diameter and the content ratio of the fine fibers were measured by the following method. First, in the SEM image, "focused fiber" is selected. "focused fibers" are fibers that do not have a blurred profile in the observation area. Then, for each focused fiber, a portion other than the thermally fused portion where thermal fusion occurs between the fibers is arbitrarily selected. Then, a line perpendicular to the longitudinal direction of the fiber of the selected portion is drawn, and the diameter length of the fiber along the line is measured as a fiber diameter. In this measurement, the focused fiber is measured at a position where a diameter line showing the diameter and length, that is, a line perpendicular to the longitudinal direction of the fiber, and a line showing the contour of the fiber are perpendicular to each other. Then, the number of fine fibers having a fiber diameter of 15 μm or less was counted as the number of fine fibers, and the ratio of the number of fine fibers to the number of focused fibers in the SEM image, that is, the percentage (%) of "number of fine fibers/number of focused fibers" was obtained. The ratio was obtained for each of a total of 5 SEM images obtained from the measurement sample, and the average value of these images was defined as "fine fiber content ratio". The average value of the fiber diameters of the focused fibers is "average fiber diameter of the fibers constituting the 1 st web 11" or "average fiber diameter of the fibers constituting the 2 nd web".
When a nonwoven fabric comprising the 1 st and 2 nd webs 11 and 12 was used and the average fiber diameter and the proportion of fine fibers of the fibers constituting the webs 11 and 12 were measured, a region of 10mm×30mm in plan view was cut out of the nonwoven fabric in the entire thickness direction using a sharp razor, and the obtained material was used as a measurement sample. In this case, the surfaces on the 1 st layer side (1 st net 11 side) and the 2 nd layer side (2 nd net 12 side) of the measurement sample were observed in an enlarged manner by the above-described method.
From the viewpoint of further improving the bulk of the nonwoven fabrics 10, 14, the weight per unit area of the 1 st and 2 nd webs 11, 12 is preferably in the following range.
The weight per unit area of the 1 st net 11 is preferably lower than the weight per unit area of the 2 nd net 12 (1 st net 11 < 2 nd net 12). Specifically, the difference between the weight per unit area of the 1 st net 11 and the weight per unit area of the 2 nd net 12 is preferably 0.5g/m 2 The above is more preferably 1g/m 2 The above is preferably 10g/m 2 Hereinafter, more preferably 8g/m 2 Hereinafter, it is preferably 0.5g/m 2 Above and 10g/m 2 Hereinafter, more preferably 1g/m 2 Above and 8g/m 2 The following is given.
The weight per unit area of the 1 st net 11 is preferably 5g/m 2 The above is more preferably 7g/m 2 The above is preferably 15g/m 2 Hereinafter, it is more preferably 12g/m 2 Hereinafter, it is preferably 5g/m 2 Above and 15g/m 2 Hereinafter, it is more preferably 7g/m 2 Above and 12g/m 2 The following is given.
Unit surface of the 2 nd web 12The total weight is preferably 5g/m 2 The above is more preferably 7g/m 2 The above is preferably 25g/m 2 Hereinafter, it is more preferably 20g/m 2 Hereinafter, it is preferably 5g/m 2 Above and 25g/m 2 Hereinafter, it is more preferably 7g/m 2 Above and 20g/m 2 The following is given.
The fineness of the 1 st and 2 nd webs 11 and 12 is preferably in the following range from the viewpoint of improving the soft feel, the fluffy feel and the smooth feel of the nonwoven fabrics 10 and 14.
The titer of the 1 st net 11 is preferably lower than the titer of the 2 nd net 12 (1 st net 11 < 2 nd net 12). Specifically, the ratio of the fineness of the 2 nd web to the fineness of the 1 st web (the fineness of the 2 nd web/the fineness of the 1 st web) is preferably 1.1 or more, more preferably 1.2 or more, further preferably 1.3 or more, and is preferably 3 or less, more preferably 2.5 or less, further preferably 2.0 or less, further preferably 1.1 or more and 3.0 or less, more preferably 1.1 or more and 2.5 or less, further preferably 1.3 or more and 2.0 or less.
The fineness of the 1 st web 11 is preferably 0.5dtex or more, more preferably 1.0dtex or more, further preferably 5.0dtex or less, more preferably 4.0dtex or less, further preferably 0.5dtex or more and 5.0dtex or less, more preferably 1.0dtex or more and 4.0dtex or less.
The fineness of the 2 nd web 12 is preferably 1.0dtex or more, more preferably 1.5dtex or more, further preferably 8.0dtex or less, more preferably 5.0dtex or less, further preferably 1.0dtex or more and 8.0dtex or less, more preferably 1.5dtex or more and 5.0dtex or less.
The fineness of the fibers can be measured by the following method. The 1 st web 11 was cut into 50mm X100 mm (area 5000 mm) 2 ) A measurement sample was prepared in the form of a rectangle. Then, the measurement sample was subjected to cross-sectional observation, and the fiber thickness was photographed at a magnification of 200 times by using a scanning electron microscope with respect to 10 standard fibers at positions spaced apart by 0.05mm in the thickness direction from one side of the 2 main surfaces of the measurement sample, to calculate a fiber thickness average value Dn (μm). Then, standard fibers were determined at positions spaced apart by 0.05mm in the thickness direction from the one surface side of the sample for measurementThe theoretical fiber-present density Pn (g/cm) was obtained by using a Differential Scanning Calorimeter (DSC) 3 ). Based on the obtained average value Dn (μm) of the fiber thickness and the theoretical fiber existence density Pn (g/cm) 3 ) The weight (g) per 10000m of fiber length was calculated, and the calculated value was set as the fineness (dtex) of the 1 st web 11.
The fineness of the 2 nd web 12 can also be obtained by the same method as that of the 1 st web 11.
When the fineness of the fibers constituting the webs 11 and 12 in the nonwoven fabric was measured using the nonwoven fabric formed of the 1 st web 11 and the 2 nd web 12, a region (area 5000 mm) of 50mm×100mm in plan view was cut out of the nonwoven fabric in the entire thickness direction using a sharp razor 2 ) The obtained material was used as a measurement sample. In this case, the average fiber thickness Dn (μm) and the theoretical fiber existing density Pn (g/cm) of the standard fibers at positions spaced apart by 0.05mm in the thickness direction from the non-blown surface of the 1 st layer (1 st web 11) of the measurement sample were obtained by the above-described method 3 ) From these values, the fineness (dtex) of the 1 st web 11 was calculated. The fineness (dtex) of the 2 nd wire 12 was calculated by the same method as that of the 1 st wire 11 except that the standard fiber was used as the target at a position spaced apart by 0.05mm in the thickness direction from the non-blown surface of the 2 nd wire (2 nd wire 12) of the measurement sample.
In the web forming step, the 1 st web 11 and the 2 nd web 12 during conveyance are joined, and the 2 nd web 12 is laminated on the 1 st web 11 to obtain a laminated web 13 (see fig. 1). The resulting laminate web 13 was used in the subsequent hot air treatment process.
The heat treatment step is a step of producing the 1 st nonwoven fabric 14 by blowing heat to the laminate web 13 and fusing the intersections of the fibers constituting the laminate web 13. In the hot air treatment step, hot air is blown onto the laminate web 13 under the following conditions (1) to (3).
(1) When the melting point of the resin having the lowest melting point among the resins constituting the heat-fusible fibers contained in the laminate web 13 is Mp, the temperature T1 of the non-blown surface of the web (laminate web 13) is Mp to mp+15 ℃.
(2) The temperature T1 is lower than the temperature T2 of the blowing face of the hot air of the web (laminate web 13) and the difference between the temperature T1 and the temperature T2 is 10 ℃ or higher and 35 ℃ or lower.
(3) The hot air supply rate is 0.30 m/s to 0.60 m/s.
In the hot air treatment step satisfying the conditions (1) to (3), the constituent fibers (heat-fusible fibers) of the laminate web 13 are moderately heat-fused while suppressing excessive flattening of the thickness of the laminate web 13. Thus, the 1 st nonwoven fabric 14 can obtain a soft and fluffy touch because the thickness of each of the 1 st and 2 nd webs 11 and 12 is well maintained. In the above-described heat treatment step, the fine fibers contained in the 1 st web 11 are prevented from being excessively heat-fused, so that the non-blown surface (the surface on the 1 st web 11 side) of the 1 st nonwoven fabric 14 is formed into a smooth touch feeling by the fine fibers. As described above, in the manufacturing method of the present embodiment, the nonwoven fabric 14 having soft, fluffy touch and having a smooth surface and excellent touch feeling can be obtained. In the manufacturing method of the present embodiment, the constituent fibers of the laminated web 13 are appropriately fused, so that a soft nonwoven fabric 14 excellent in strength can be obtained.
On the other hand, when a conventional hot air method is used for the laminate web 13 including the fine fibers, the fine fibers are excessively fused, and the original smooth touch of the fine fibers is lowered, so that the hand of the hot air nonwoven fabric may be impaired. In addition, the web is excessively flattened by hot air of the hot air method, and thus the fluffy feeling may be impaired.
The following describes the conditions (1) to (3).
The condition of the above (1) is represented by the following formula (i).
Mp≤T1≤Mp+15℃···(i)
Mp: the melting point of the lowest melting point resin among the resins constituting the heat-fusible fibers contained in the web (laminate web 13)
T1: temperature of non-blown face of web (laminated web 13)
Mp is the melting point of the lowest melting point resin among the resins constituting the heat-fusible fibers contained in the laminate web 13. When the heat-fusible fibers of the laminate web 13 are composed of a plurality of resins, such as core-sheath type composite fibers, mp is the melting point of the lowest melting point resin among these resins. The softening point is set in the absence of a resin having a clear melting point.
The temperature T1 is a temperature at a position P1 (see fig. 2) which is separated by 10cm in the normal direction from the non-blown conveying surface f1 of the air-permeable conveying member 31 of the hot air treatment conveying path r1 to which the hot air is blown, in view of the convenience of temperature measurement. The "hot air treatment conveying path r1" is a path facing the hot air supply port of the blower 32, among the conveying paths of the laminated web 13 formed by the air-permeable conveying member 31. The "non-blowing conveyance surface f1" is a surface of the air-permeable conveyance member 31 on the opposite side to the surface facing the hot air supply port of the blower 32. The temperature at the position P1 corresponds to the temperature T1 of the non-blown surface of the laminate web 13.
The temperature T1 affects the degree of thermal fusion on the non-blown surface (layer 1 side surface) side of the nonwoven fabrics 10 and 14 and the feel. Under the condition of (1) above, the temperature T1 is set to Mp or higher to ensure the strength of the non-blown surface, and the temperature T1 is set to mp+15 ℃ or lower to suppress excessive thermal fusion of the fine fibers, thereby improving the feel of the non-blown surface. From the viewpoint of further improving the feel, the difference between the temperatures T1 and Mp is 15 ℃ or less, preferably 0.5 ℃ or more, more preferably 1 ℃ or more, further preferably 10 ℃ or less, more preferably 5 ℃ or less, and further preferably 0.5 ℃ or more and 15 ℃ or less, more preferably 1 ℃ or more and 10 ℃ or less, further preferably 1 ℃ or more and 5 ℃ or less under the conditions of (1) above.
The condition of the above (2) is represented by the following formula (ii).
10℃≤T2-T1≤35℃···(ii)
T2: temperature of the blown surface of the web (laminate web 13)
In the above formula (ii), T2 > T1 is used as a precondition.
The temperature T2 is a temperature of the hot air treatment conveying path r1 at a position P2 (see fig. 2) which is 10cm away from the blowing conveying surface f2 of the air-permeable conveying member 31 in the normal direction, in view of the convenience of temperature measurement. The "blowing conveyance surface f2" is a surface of the air-permeable conveyance member 31 facing the hot air supply port of the blower 32. The temperature at the position P2 corresponds to the temperature T2 of the blowing surface of the laminate web 13.
For measuring the temperatures T1 and T2, a known measuring means such as a thermocouple type temperature sensor and a temperature display is used. The temperature T1 and the temperature T2 were measured by the following methods. When the hot air treatment conveyance path r1 is divided into four sections, i.e., the 1 st section S1, the 2 nd section S2, the 3 rd section S3 and the 4 th section S4, in this order from the upstream side in the conveyance direction X, the temperatures at the positions P1 and P2 at the midpoints of the conveyance path lengths of the four sections S1, S2, S3 and S4 are measured. Thereafter, the average temperature of the position P1 and the average temperature of the position P2 in the four sections S1, S2, S3, S4 are calculated, and the calculated average temperatures are set as the temperatures T1 and T2.
The temperature T2 affects the thermal fusion between the constituent fibers of the nonwoven fabrics 10, 14. Under the condition (2), the difference (T2-T1) between the temperature T1 and the temperature T2 is set to 10 ℃ or higher, whereby the constituent fibers of the laminated web 13 are thermally fused to ensure the strength of the entire nonwoven fabrics 10, 14, and the difference (T2-T1) between the temperature T1 and the temperature T2 is set to 35 ℃ or lower, whereby excessive thermal fusion of the constituent fibers on the blown surface side of the laminated web 13 is suppressed. This can impart strength and flexibility to the nonwoven fabrics 10 and 14. In view of ensuring the strength and flexibility of the nonwoven fabrics 10, 14 more reliably, the difference (T2-T1) between the temperature T1 and the temperature T2 is preferably 12 ℃ or higher, more preferably 15 ℃ or higher, still more preferably 30 ℃ or lower, more preferably 25 ℃ or lower, still more preferably 12 ℃ or higher and 30 ℃ or lower, still more preferably 15 ℃ or higher and 25 ℃ or lower under the condition of (2) above.
Under the condition (3), the hot air supply speed of the hot air treatment conveying path r1 is set to be 0.30 m/sec or more and 0.60 m/sec or less.
The supply speed of the hot air affects the thickness of the nonwoven fabrics 10, 14. Under the condition (3), the original thickness of the laminate web 13 is preferably maintained by appropriately thermally fusing the constituent fibers of the laminate web 13 by setting the hot air supply rate to 0.30 m/sec or more and setting the hot air supply rate to 0.60 m/sec or less. This can impart cushioning properties and a fluffy touch to the nonwoven fabrics 10 and 14. In view of ensuring the cushioning properties and the fluffy touch of the nonwoven fabrics 10 and 14 more reliably, the hot air supply rate is preferably 0.33 m/sec or more, more preferably 0.35 m/sec or more, still more preferably 0.57 m/sec or less, still more preferably 0.50 m/sec or less, and still more preferably 0.33 m/sec or more and 0.57 m/sec or less, still more preferably 0.35 m/sec or more and 0.50 m/sec or less under the condition of (3) above.
The hot air supply speed was measured at a position P2 of the hot air treatment conveying path r1 which was 10cm away from the blowing conveying surface f2 of the air-permeable conveying member 31 in the normal direction by using a known anemometer (for example, modem 6162, modem 0203, etc. of anemarast manufactured by Kanomax corporation, japan).
As described above, the 1 st web 11 of the laminated web 13 contains fine fibers. In the heat treatment step, from the viewpoint of further suppressing excessive thermal fusion of the fine fibers and moderate thermal fusion between the constituent fibers of the 2 nd web 12, it is preferable to blow heat from the 2 nd web 12 side to the laminate web 13. Thereby, the non-blown surface of the laminate web 13 can be made smoother, and the strength of the 1 st nonwoven fabric 14 can be ensured more reliably.
The hot air treatment step of the present embodiment continuously supplies the laminate web 13 to the endless air-permeable transport member 31, transports the laminate web 13, and simultaneously continuously blows hot air to the laminate web 13. As described above, in the manufacturing method of the present embodiment, the hot air treatment process is continuously performed while continuously conveying the laminate web 13. The above-described hot air treatment conveyance path r1 is included in a part of the endless path r2 of the air-permeable conveyance member 31 (see fig. 2).
Immediately after the start of the operation of the manufacturing apparatus 100, the temperature of the air-permeable transport member 31 is substantially normal temperature, but when the operation is continued, the temperature of the air-permeable transport member 31 may be increased by the hot air of the blower 32. For this reason, the temperature T2 may also rise. In the heat treatment step, the breathable conveying member 31 heated by continuous blowing of the heat air is preferably cooled before the laminate web 13 is supplied, in order to further suppress an excessive increase in the temperature T2 in the heat treatment step and to further smooth the surface of the nonwoven fabrics 10, 14 on the blowing surface side. This step of cooling is also referred to as a "cooling step" hereinafter. The cooling step of the present embodiment is performed in the circulating path r2 of the air-permeable transport member 31 by the cooling device 50 disposed in a path other than the hot air treatment transport path r 1. For example, the cooling device 50 blows cold air to the air-permeable transport member 31 before it enters the hot air treatment transport path r1, and cools the air-permeable transport member 31. As the cooling device 50, any one of the conveying rollers 34a, 34b, 34c, 34d may be used as a cooling roller. The cooling roller is provided with a refrigerant such as water or gas inside.
From the same viewpoints as described above, the temperature of the breathable conveying member 31 after the cooling step and before the hot air treatment step is preferably 25 ℃ or higher, more preferably 30 ℃ or higher, and further preferably 130 ℃ or lower, more preferably 120 ℃ or lower, and further preferably 25 ℃ or higher and 130 ℃ or lower, more preferably 30 ℃ or higher and 120 ℃ or lower. At the inlet of the hot air treatment conveying path r1, the temperature of the air-permeable conveying member 31 after the cooling step and before the hot air treatment step is measured by a known measuring means such as a thermocouple type temperature sensor or a temperature display.
From the same viewpoint as described above, the temperature difference between Mp and the temperature of the air-permeable transport member 31 cooled by the cooling step (mp—the temperature of the air-permeable transport member 31 cooled by the cooling step) is preferably greater than 0 ℃, more preferably 10 ℃ or higher, and further preferably 105 ℃ or lower, more preferably 90 ℃ or lower, and further preferably greater than 0 ℃ and 105 ℃ or lower, more preferably 10 ℃ or higher and 90 ℃ or lower.
The 1 st nonwoven fabric 14 was obtained by the above-described hot air treatment step. As described above, the 1 st nonwoven fabric 14 is a nonwoven fabric excellent in touch feel and strength, but in the manufacturing method of the present embodiment, a calendering step of applying a calendering process to the 1 st nonwoven fabric 14 is further performed. The calendaring process can smooth the surface of the nonwoven fabric, further improving the smoothness when contacting the skin. In addition, the density of the constituent fibers of the nonwoven fabric can be increased, and the softness can be further improved. As described above, the thickness of each of the 1 st and 2 nd webs 11 and 12 of the 1 st nonwoven fabric 14 is well maintained, and the nonwoven fabric has a fluffy touch. For this reason, even if the 1 st nonwoven fabric 14 is subjected to the calender process, the thickness is easily recovered, and therefore the 2 nd nonwoven fabric 10 obtained through the calender process also has a good fluffy touch.
The calendering in the calendering step may be performed in two or more stages, or may be performed in one stage, and preferably at least in one stage or more. From the viewpoint of further improving the smoothness and softness of the surface of the 2 nd nonwoven fabric 10, the calendering step is preferably performed in multiple stages.
In the calendering process of the present embodiment, a two-stage calendering process is applied to the 1 st nonwoven fabric 14. The 1 st nonwoven fabric 14 is introduced between the calender roll 41 and the 1 st resin roll 42, and subjected to the first-stage calender process. The 1 st nonwoven fabric 14 is introduced between the calender roll 41 and the 2 nd resin roll 43, and the second-stage calender process is performed. In the first stage and the second stage of the calender processing, the 1 st layer of the 1 st nonwoven fabric 14 is brought into contact with the calender roll 41.
The calendaring process is preferably performed under the following condition (C1).
Temperature: 25 DEG C
Line pressure: 20N/cm or more and 500N/cm or less
And (3) roller: a pair of calender rolls are used, one of which is a metal calender roll and the other is a resin roll having a D hardness (JIS K6253) of 40 to 100 degrees.
When the calendering process is performed in multiple stages in the calendering process, the condition (C1) is preferably satisfied in any one of the calendering processes. That is, it is preferable to perform the multi-stage calendering under the condition (C1) described above.
By performing the calender process satisfying the condition (C1), the surface of the 1 st layer in contact with the calender roll 41 becomes smoother, and the softness of the 2 nd nonwoven fabric 10 is further improved. Further, excessive compression of the constituent fibers is suppressed, and the bulkiness of the 2 nd nonwoven fabric 10 can be further maintained. This is because the layer 1 side facing the calender roll 41 is pinched by the calender process, and the fibers contained in the layer 1 are deformed and flattened, and the densification is achieved by the pinching. In addition, the nonwoven fabric 14 is deformed or broken at a part of the bonding points between the fibers by the "kneading" action by the nip, and the nonwoven fabric 14 becomes soft. The fibers contained in the 2 nd layer facing the resin rolls 42 and 43 are not easily deformed due to the soft material of the resin rolls 42 and 43, and are hardly deformed and densified. The major axis direction of the cross section of the fibers contained in the flattened layer 1 is oriented in the plane direction of the nonwoven fabric 14.
The calender roll 41 may be a smooth roll subjected to mirror finishing, or may be a roll to which fine irregularities such as a texture are applied. The calender roll 41 is preferably a metal roll.
As the 1 st resin roll 42 and the 2 nd resin roll 43, for example, rolls made of a resin such as hard rubber, silicone rubber, urethane rubber, NBR, EPDM, or the like can be used.
Under the condition (C1), one or both of the 1 st resin roll 42 and the 2 nd resin roll 43 preferably has a D hardness (JIS K6253) of the constituent resin of the roll surface of 40 degrees or more and 100 degrees or less, more preferably 70 degrees or more and 95 degrees or less.
The calender roll 41 and/or the resin rolls 42, 43 may be used in a heated state or may be used in a non-heated state under the condition (C1). When used in a non-heated state, the calendaring process is performed at room temperature (25 ℃ C.).
Under the condition (C1), the line pressure of the calender process is preferably 20N/cm or more and 500N/cm or less, and more preferably 20N/cm or more and 300N/cm or less from the viewpoint of further improving the bulk of the 2 nd nonwoven fabric 10. The calender roll 41 and/or the resin rolls 42, 43 may be used in a heated state or a non-heated state, but from the viewpoint of improving the bulk feeling and the touch at the same time, it is preferable to use them in a non-heated state.
In the case of performing the two-stage calendering as in the present embodiment, the condition (C1) may be satisfied in both stages, or the condition (C1) may be satisfied in either one of the stages. From the viewpoint of making the surface of the 1 st layer of the 2 nd nonwoven fabric 10 smoother, it is preferable that the calendering in the second stage satisfies the condition (C1) and that the line pressure of the calendering in the first stage is higher than that in the second stage. From the same viewpoint as described above, the line pressure in the first stage of the calendaring is preferably 50N/cm or more and 700N/cm or less, more preferably 100N/cm or more and 300N/cm or less.
From the viewpoint of more reliably obtaining a bulky touch, it is preferable to perform an additional step of further subjecting the 2 nd nonwoven fabric 10 after the calender treatment to a heat treatment or calender treatment so that the compression work amount WC becomes 1.2 mN.cm/cm 2 Above and 1.6 mN.cm/cm 2 The following is given. That is, it is preferable to apply an additional step to the 2 nd nonwoven fabric 10 so that the compression work WC of the 2 nd nonwoven fabric 10 becomes 1.2 mN.cm/cm 2 Above and 1.6 mN.cm/cm 2 The following is given.
[ measurement of compression work ]
It is generally known that the compression work can be expressed by a measured value of KES (KAWABATA EVALUATION SYSTEM) (reference: standardization and analysis of hand feeling evaluation (2 nd edition), and release of the handfeel evaluation from Sichuan end Ji Xiong, showa 55, 7 months and 10 days). For the measurement of the compression work, a compression test apparatus KES-G5 manufactured by Kato Tech Co., ltd was used. First, a nonwoven fabric to be measured was mounted on a test bed of a compression test apparatus, and the test bed had an area of 2cm 2 Is compressed between the circular planar steel plates. In the compression step, the compression speed was set to 0.2cm/sec, and the compression maximum load was set to 2450mN/cm 2 . The compression Work (WC) is represented by the following formula (1) and has the unit of "mN cm/cm 2 ". In the following formula, tm represents 2450mN/cm 2 Thickness under load (24.5 kPa), T 0 Represent 4.902mN/cm 2 (49 Pa) thickness under load. In addition, P in the following formula (1) a Represents the measured load (mN/cm) during the compression process 2 ). The larger the compression Work (WC) value, the more fluffy the touch is formed.
[ number 1]
When the calendering process is applied to the 2 nd nonwoven fabric 10 in the additional step, the same conditions as those in the calendering process may be used. For example, the calendaring process may be performed in a single stage or two or more stages in the additional process.
When the heat treatment is applied to the 2 nd nonwoven fabric 10 in the additional step, the 2 nd nonwoven fabric 10 is preferably heat-treated at a temperature lower than the melting point Mp of the heat-fusible fibers contained in the 2 nd nonwoven fabric 10. Examples of the heat treatment method include a method of blowing hot air to the 2 nd nonwoven fabric 10 and a method of heating the 2 nd nonwoven fabric 10 in a predetermined temperature environment without air. In the above method of blowing hot air, the aforementioned hot air treatment unit 30 may be used under the condition that the temperature T2 is lower than M.
The 2 nd nonwoven fabric 10 was obtained by the above-described production method. The 2 nd nonwoven fabric 10 and the 1 st nonwoven fabric 14 obtained in the aforementioned hot air treatment step are each suitable for use in nonwoven fabric products. The nonwoven fabric product is a product made of a nonwoven fabric or a product provided with the nonwoven fabric as a constituent member. As nonwoven fabric products, for example, there are widely used absorbent articles such as disposable diapers and sanitary napkins, thermal appliances such as eye masks, surgical gowns, masks, cleaning sheets, wiping sheets, and the like. The "absorbent article" is widely used to absorb body fluids (urine, soft feces, menstrual blood, sweat, etc.) discharged from a human body, and includes, for example, disposable diapers, sanitary napkins, underpants, incontinence pads, and the like.
An absorbent article typically includes a liquid-permeable front sheet disposed in a position relatively close to the skin of the wearer, a liquid-permeable or liquid-impermeable or hydrophobic back sheet disposed in a position relatively far from the skin of the wearer, and a liquid-retentive absorbent member interposed between the two sheets. The absorbent article may further include an outer package formed on an outer surface thereof.
When the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 are used as the constituent members of the absorbent article, the nonwoven fabrics 10 and 14 are preferably used as the constituent members to be brought into contact with the skin of a user such as a wearer. In this case, the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 are more preferably used such that the 1 st layer side surface becomes a skin contact surface. Since the 1 st layer side of these nonwoven fabrics 10, 14 is flat and smooth, a good wearing feel can be obtained. Examples of the constituent members that come into contact with the skin of a user such as a wearer include a front sheet and an outer package.
The 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 are each produced as a belt-like nonwoven fabric having a longitudinal direction aligned with the conveyance direction X (MD direction) (see fig. 1). The direction (width direction) orthogonal to the longitudinal direction of these nonwoven fabrics 10, 14 coincides with the direction (CD direction) orthogonal to the conveyance direction X. From the viewpoint of ensuring the strength more reliably, the tensile strength in the MD direction of either one or both of the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 to be produced is preferably 10N/50mm or more, more preferably 20N/50mm or more, further preferably 100N/50mm or less, more preferably 70N/50mm or less, and further preferably 10N/50mm or more and 100N/50mm or less, more preferably 20N/50mm or more and 70N/50mm or less. From the same viewpoints as described above, the tensile strength in the CD direction of each of the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 to be produced is preferably 4N/50mm or more, more preferably 5N/50mm or more, further preferably 15N/50mm or less, more preferably 12N/50mm or less, and further preferably 4N/50mm or more and 15N/50mm or less, more preferably 5N/50mm or more and 12N/50mm or less.
The respective measurement methods of the tensile strength in the MD direction and the tensile strength in the CD direction are described in detail in [ measurement of tensile strength ] of examples described later. In this [ measurement of tensile strength ], when a measurement sample cannot be obtained at the time of cutting out, the measurement sample is cut out with the length in the width direction set to 50mm and the length in the length direction shortened by 50mm (for example, 50mm×150mm, or 50mm×100 mm). In this case, the distance between the chucks of the tensile tester was set to be 50mm shorter than the length of the measurement sample in the longitudinal direction. Even if the length of the measurement sample in the longitudinal direction is changed in this way, the measurement result of the tensile strength can be directly compared.
From the viewpoint of suppressing the appearance fuzzing and further improving the hand of the nonwoven fabric, the number of fuzzed fibers per unit area of either or both of the 1 st nonwoven fabric 14 and the 2 nd nonwoven fabric 10 to be produced is preferably 20 or less, more preferably 10 or less, and most preferably 0. That is, from the above point of view, the fewer the number of fibers that develop fuzzing per unit area, the more preferable. The method for measuring the number of fibers is described in detail in examples (measurement of the number of fibers that develop fuzzing per unit area) described later. In this [ measurement of the number of fibers that have developed fuzzing per unit area ], when a 10cm×10cm measurement piece cannot be cut out of nonwoven fabric, the measurement piece is set to have a size of 7cm×7cm.
The present invention has been described above based on preferred embodiments thereof, but the present invention is not limited to the above embodiments and can be appropriately modified. The above-described respective configurations may be appropriately combined.
For example, in the manufacturing method of the above embodiment, the laminated web 13 in which the 1 st web 11 and the 2 nd web 12 are laminated is used, but a single-layer web may be used instead. In this case, the single layer web contains fine fibers.
The manufacturing method of the above embodiment includes a cooling step, but the cooling step may not be included if the conditions (1) to (3) described above in the hot air treatment step are satisfied.
Examples
The present invention will be described in further detail with reference to examples. However, the scope of the present invention is not limited by this embodiment.
[ example 1 ]
The 2 nd nonwoven fabric 10 was manufactured using the manufacturing apparatus 100 shown in fig. 1. First, a web forming step is performed. The raw material fiber of the 1 st web 11 was a heat-fusible fiber formed of a concentric core-sheath type composite fiber (core-sheath ratio 50% by mass: 50% by mass) containing PET as a core component and PE as a sheath component. The raw material fiber of the 1 st net 11 is a fine fiber with a fiber diameter of 12.4 μm and a fineness of 1.3dtex, and participates in the tree formation The melting point Mp of the resin (PE of the sheath component) having the lowest melting point among the fats is 130 ℃. The raw material fiber was introduced into a 1 st guide 21 to produce a 1 st web 11 (weight per unit area 10 g/m) 2 )。
The raw material fiber of the 2 nd web 12 was a heat-fusible fiber formed of a concentric core-sheath type composite fiber (core-sheath ratio 50% by mass: 50% by mass) having a core component including PET and a sheath component including PE. The raw material fiber of the 2 nd web 12 had a fiber diameter of 16.7 μm and a fineness of 2.0dtex, and the melting point Mp of the lowest melting point resin (PE of the sheath component) among the constituent resins was 130 ℃. The raw material fiber was introduced into a 2 nd guide 22 to produce a 2 nd web 12 (15 g/m weight per unit area) 2 ). The average fiber diameter of the fibers constituting the 1 st web 11 was 12.4 μm, and the average fiber diameter of the fibers constituting the 2 nd web 12 was 16.7 μm. The average fiber diameter was determined by the method described above. Thereafter, the 2 nd wire 12 is laminated on the 1 st wire 11 to produce a laminated wire 13.
Then, the laminate web 13 is subjected to a hot air treatment step using the hot air treatment unit 30. At this time, the surface on the 2 nd wire 12 side is set as the blowing surface and the surface on the 1 st wire 11 side is set as the non-blowing surface in the laminated wire 13. The conditions of the hot air treatment step (temperature T1, difference between temperature T1 and Mp, temperature T2, difference between temperature T1 and temperature T2, and supply rate of hot air) are shown in table 1 below.
In the hot air treatment step, a cooling step of cooling the air-permeable transport member 31 is performed before the laminated web 13 is supplied. The temperature of the air-permeable transport member 31 after the cooling process and before the hot air treatment process was 105 ℃. The 1 st nonwoven fabric 14 was produced by the above-described hot air treatment step.
Then, a calendaring process is performed using the calendaring unit 40. The calendering step as shown in fig. 1, the 1 st nonwoven fabric 14 is subjected to a two-stage calendering process. The calender roll 41 is a smooth roll having a metal surface subjected to mirror finishing. For the surface of the 1 st resin roll 42, a roll made of hard rubber and having a D hardness (JIS K6253) of 40 degrees to 100 degrees inclusive is used. The 2 nd resin roller 43 uses the same roller as the 1 st resin roller 42. The first and second stages of calendering were carried out at room temperature (25 ℃). The line pressures of the first stage and the second stage of the calendering are shown in table 1 below. The 2 nd nonwoven fabric 10 was produced by the above-mentioned calendering process.
Examples 2 to 5
In examples 2 to 4, a 2 nd nonwoven fabric 10 was produced in the same manner as in example 1, except that the conditions of the hot air treatment step were different.
The 1 st nonwoven fabric 14 obtained before the calender step in example 1 was used as the nonwoven fabric obtained in example 5.
Comparative examples 1 to 4
In comparative examples 1 to 3, a 2 nd nonwoven fabric 10 was produced in the same manner as in example 1, except that the conditions of the hot air treatment step were different.
In comparative example 4, a 2 nd nonwoven fabric 10 was produced in the same manner as in example 1, except that the conditions of the hot air treatment step were different and the cooling step was not performed.
[ evaluation ]
The 2 nd nonwoven fabric 10 of examples 1 to 4 and comparative examples 1 to 4 and the 1 st nonwoven fabric 14 of example 5 were measured for thickness, compression work WC and tensile strength. The compression work WC was measured by the method described above. Further, the average deviation MMD of the friction coefficient was measured for the layer 1 side surface of each nonwoven fabric. The measurement results are shown in table 1 below.
[ measurement of thickness ]
The nonwoven fabric as the measurement target was given 4.9N/cm 2 In this state, 5 or more points were measured using a laser displacement meter (manufactured by Omron corporation, high-precision displacement sensor ZS-LD80 (trade name)). The arithmetic average of the measured values was set as the thickness (mm).
[ measurement of tensile Strength ]
The nonwoven fabrics of each example and each comparative example were belt-shaped nonwoven fabrics, and the longitudinal direction was aligned with the conveyance direction X (MD direction). The direction (width direction) of the nonwoven fabric perpendicular to the longitudinal direction coincides with the direction (CD direction) perpendicular to the transport direction X. From the nonwoven fabric to be measured, a sheet having a length of 200mm and a width of 50mm was cut out, and the sheet was used as a sheet for measuring tensile strength in the MD direction. The measurement piece was mounted between chucks of a tensile testing machine (model "AUTOGRAPH AG-X" manufactured by Shimadzu corporation) so that the longitudinal direction of the measurement piece was aligned with the tensile direction. The distance between the chucks was set to 150mm. Then, the attached measuring sheet was pulled at a speed of 300mm/min to obtain a graph of tensile strength accompanied by a change in the tensile distance. The maximum tensile strength was determined from the obtained graph. This measurement of the maximum tensile strength was repeated 3 times, and the average value thereof was defined as the tensile strength in the MD direction.
Further, a nonwoven fabric as a measurement target was cut into a size of 50mm in the longitudinal direction and 200mm in the width direction, and the cut was used as a measurement piece of tensile strength in the CD direction. The tensile strength in the CD direction was measured by the same method as the tensile strength in the MD direction except that the measuring sheet was used.
[ measurement of average deviation MMD of Friction coefficient ]
A KES-FB4 surface tester (manufactured by Kato Tech Co., ltd.) was used as the measurement surface on the 1 st web 11 side (the 1 st layer side), and 5kPa (50 gf/cm) was applied to the measurement object with a contact 2 ) In a state of a load of (2), the contact was moved in the horizontal direction at a constant speed of 0.1cm/sec by 3cm, and the average deviation MMD of the friction coefficient of the region in which the contact was moved was measured. The measurement was performed at 3 different points of the nonwoven fabric, and the average value thereof was defined as the average deviation MMD of the friction coefficient of the nonwoven fabric. The lower the average deviation MMD of the friction coefficient is, the smoother the layer 1 side surface can be evaluated.
In order to evaluate fuzzing of the 2 nd nonwoven fabrics 10 of examples 1 to 4 and comparative examples 1 to 4 and the 1 st nonwoven fabric 14 of example 5, fuzzing fibers per unit area were measured. The measurement results are shown in table 1 below.
[ measurement of the number of fluffed fibers per unit area ]
FIG. 3 is a schematic view showing a method for measuring the number of fibers forming a nonwoven fabric, which have been fluffed, in a 65% RH atmosphere at 22 ℃. First, a 10cm×10cm measurement piece 104 was cut out of a nonwoven fabric to be measured with a sharp razor. Then, as shown in fig. 3 (a), the measurement sheet 104 was folded into a mountain, and this was placed on A4-size black backing paper (not shown), and as shown in fig. 3 (b), A4-size black backing paper 101 having holes 107 of 1cm in the vertical direction by 1cm in the horizontal direction was placed on the measurement sheet 104 on the backing paper. At this time, the crease 105 of the measurement sheet 104 is disposed so as to be visible from the hole 107 of the upper black backing paper. For example, "KENRAN (Black) order weight 265g" of Fuji co paper Co., ltd. Is used as the base paper disposed above and below the measurement plate 104. In fig. 3, for convenience of explanation, the backing paper 101 is shown in white. Then, 2 weights 102 of 50g were placed on the backing paper 101 placed on the test piece 104. At this time, the weight 102 was placed on the fold 105 of the measurement piece 104 at a position separated by 5cm from both side edges of the hole 107 of the backing paper 101 placed on the measurement piece 104 to the outside in the direction along the fold 105. Thereby, the measurement piece 104 is brought into a completely folded state. Then, as shown in FIG. 3 (c), the inside of the hole 107 of the backing paper was observed at a magnification of 30 times by using a microscope (VHX-900, manufactured by Keyence, inc.). From this observation, the number of fibers whose distal ends are located above the virtual line 108, which is obtained by moving the virtual line 108 1mm in parallel upward from the crease 105 of the measuring sheet 104, was counted as the number of fibers in which fuzzing occurred. When there are fibers 106a traversing the virtual line 108 2 times (see fig. 3 (c)), the number of fibers is 2. In the example shown in fig. 3 (c), there are 4 fibers in which the virtual line 108 is traversed 1 time, and 1 fiber 106a in which the virtual line 108 is traversed 2 times, and the number of fibers in which fuzzing occurs is 6 because the number of fibers 106a traversed 2 times is counted as 2. The number of the fibers to be fluffed was counted for 9 measurement pieces cut from the nonwoven fabric to be measured, and the average (rounded to an integer) was set to the number of the fibers to be fluffed per unit area (1 cm×1 cm). The surface on the 1 st web 11 side (the surface on the 1 st layer side) was set as the measurement surface.
Further, the 2 nd nonwoven fabrics 10 of examples 1 to 4 and comparative examples 1 to 4 and the 1 st nonwoven fabric 14 of example 5 were subjected to sensory evaluation of softness and fluffy touch. The evaluation results are shown in table 1 below.
[ evaluation of softness and fluffy touch ]
The test piece was a material cut out of a nonwoven fabric to be evaluated in a size of 10cm×10 cm. The softness and fluffy touch of the nonwoven fabric were evaluated by contacting the panel member with a test piece, using 3 adult men familiar with the evaluation of the touch of the nonwoven fabric as the panel member and the 1 st web 11 side surface (1 st layer side surface) as the measurement surface. Specifically, the evaluation was performed on 5 grades of 1 to 5 points. A score of 5 indicates the highest evaluation. The method of contact of the test piece is not specified, and the panelists freely contact the test piece to evaluate the test piece. The average value of 3 panelists was rounded to one point below the decimal point to calculate an evaluation score. The evaluation results are shown in table 1 below.
TABLE 1
As shown in table 1, the nonwoven fabrics of examples 1 to 5 had a larger thickness than the nonwoven fabrics of comparative examples 1, 3 and 4, and the compression work WC was larger than the nonwoven fabrics of comparative examples 1 and 4. The nonwoven fabrics of examples 1 to 5 had tensile strengths of 40.0N or more in the MD direction and 6.4 or more in the CD direction. The nonwoven fabric of example 5 was not only thicker than the nonwoven fabric of comparative example 2, but also less fluffing than the nonwoven fabric of comparative example 2, and had good feel both in appearance and in touch.
The nonwoven fabrics of examples 1 to 5 have smaller average deviation MMD of the friction coefficient of the layer 1 side surface than the nonwoven fabrics of comparative examples 1 to 4. The results showed that the surface of the 1 st layer side of the nonwoven fabrics of examples 1 to 5 was smooth.
The nonwoven fabrics of examples 1 to 5 had 9 or less fibers per unit area that had developed fuzzing on the layer 1 side surface, and exhibited little fuzzing on the surface.
The nonwoven fabrics of examples 1 to 5 had a sensory evaluation of softness of 5.3 or more and a sensory evaluation of fluffy touch of 4.6 or more.
The results show that the nonwoven fabrics of examples 1 to 5 are excellent in the combination of the touch feeling such as smoothness, softness and bulk, and have both touch feeling and strength compared with the nonwoven fabrics of comparative examples 1 to 4.
Industrial applicability
According to the method for producing a nonwoven fabric of the present invention, a nonwoven fabric containing fibers having a small fiber diameter and having excellent touch feeling and strength can be obtained.

Claims (38)

1. A method for manufacturing a non-woven fabric,
blowing hot air to a web comprising thermally fusible fibers having a fiber diameter of 15 μm or less under the following conditions to fuse intersections of fibers constituting the web:
(1) When the melting point of the resin with the lowest melting point among the resins constituting the heat-fusible fibers is Mp, the temperature T1 of the surface of the web opposite to the surface on which the hot air is blown is not less than Mp and not more than Mp+15℃,
(2) The temperature T1 is lower than the temperature T2 of the blowing face of the hot air of the web and the difference between the temperature T1 and the temperature T2 is 10 ℃ or higher and 35 ℃ or lower,
(3) The hot air supply rate is 0.30 m/s to 0.60 m/s.
2. The method for producing a nonwoven fabric according to claim 1, wherein,
the net has a 1 st net and a 2 nd net,
the 1 st web contains heat-fusible fibers having a fiber diameter of 15 μm or less.
3. The method for producing a nonwoven fabric according to claim 2, wherein,
the content of the heat-fusible fibers having a fiber diameter of 15 μm or less in the 1 st web is 25% or more, preferably 30% or more and 100% or less.
4. The method for producing a nonwoven fabric according to claim 2 or 3, wherein,
the average fiber diameter of the fibers constituting the 2 nd web is larger than the average fiber diameter of the fibers constituting the 1 st web.
5. The method for producing a nonwoven fabric according to any one of claims 2 to 4, wherein,
the difference between the average fiber diameter of the fibers constituting the 1 st web and the average fiber diameter of the fibers constituting the 2 nd web is 0.5 μm or more and 25 μm or less, preferably 1 μm or more and 15 μm or less.
6. The method for producing a nonwoven fabric according to any one of claims 2 to 5, wherein,
The average fiber diameter of the fibers constituting the 1 st web is 5 μm or more and 20 μm or less, preferably 8 μm or more and 15 μm or less.
7. The method for producing a nonwoven fabric according to any one of claims 2 to 6, wherein,
the average fiber diameter of the fibers constituting the 2 nd web is 5 μm or more and 30 μm or less, preferably 8 μm or more and 20 μm or less.
8. The method for producing a nonwoven fabric according to any one of claims 2 to 7, wherein,
the weight per unit area of the 1 st net is lower than the weight per unit area of the 2 nd net.
9. The method for producing a nonwoven fabric according to claim 8, wherein,
the difference between the weight per unit area of the 1 st net and the weight per unit area of the 2 nd net was 0.5g/m 2 Above and 10g/m 2 Hereinafter, it is preferably 1g/m 2 Above and 8g/m 2 The following is given.
10. The method for producing a nonwoven fabric according to claim 8 or 9, wherein,
the weight per unit area of the 1 st net is 5g/m 2 Above mentionedAnd 15g/m 2 Hereinafter, it is preferably 7g/m 2 Above and 12g/m 2 The following is given.
11. The method for producing a nonwoven fabric according to any one of claims 8 to 10, wherein,
the weight per unit area of the 2 nd net is 5g/m 2 Above and 25g/m 2 Hereinafter, it is preferably 7g/m 2 Above and 20g/m 2 The following is given.
12. The method for producing a nonwoven fabric according to any one of claims 2 to 11, wherein,
The fineness of the 1 st web is 0.5dtex or more and 5.0dtex or less, more preferably 1.0dtex or more and 4.0dtex or less.
13. The method for producing a nonwoven fabric according to any one of claims 2 to 12, wherein,
the fineness of the 2 nd web is 1.0dtex or more and 8.0dtex or less, more preferably 1.5dtex or more and 5.0dtex or less.
14. The method for producing a nonwoven fabric according to any one of claims 2 to 13, wherein,
the ratio of the fineness of the 2 nd web to the fineness of the 1 st web, that is, the fineness of the 2 nd web/the fineness of the 1 st web is 1.1 or more and 3.0 or less, preferably 1.1 or more and 2.5 or less, more preferably 1.3 or more and 2.0 or less.
15. The method for producing a nonwoven fabric according to any one of claims 2 to 14, wherein,
blowing the hot air from the 2 nd wire side.
16. The method for producing a nonwoven fabric according to any one of claims 1 to 15, wherein,
under the condition of (1), the difference between the temperatures T1 and Mp is 0.5 ℃ or higher and 15 ℃ or lower, preferably 1 ℃ or higher and 10 ℃ or lower, and more preferably 1 ℃ or higher and 5 ℃ or lower.
17. The method for producing a nonwoven fabric according to any one of claims 1 to 16, wherein,
under the condition of (2), the difference between the temperature T1 and the temperature T2, i.e., T2-T1, is 12℃or more and 30℃or less, preferably 15℃or more and 25℃or less.
18. The method for producing a nonwoven fabric according to any one of claims 1 to 17, wherein,
under the condition of (3), the hot air supply rate is 0.33 m/sec to 0.57 m/sec, preferably 0.35 m/sec to 0.50 m/sec.
19. The method for producing a nonwoven fabric according to any one of claims 1 to 18, comprising a step of continuously blowing the hot air onto the web while continuously feeding the web onto the endless air-permeable transport member and transporting the web,
in the step, the air-permeable transport member heated by the continuous blowing of the hot air is cooled before the web is supplied.
20. The method for producing a nonwoven fabric according to claim 19, wherein,
the temperature of the breathable conveying member after cooling and before continuous blowing of the hot air is 25 ℃ or more and 130 ℃ or less, preferably 30 ℃ or more and 120 ℃ or less.
21. The method for producing a nonwoven fabric according to claim 19 or 20, wherein,
the temperature difference between Mp and the cooled temperature of the breathable conveying member, that is, mp-the temperature of the breathable conveying member cooled in the cooling step is greater than 0 ℃ and equal to or less than 105 ℃, preferably 10 ℃ to 90 ℃.
22. The method for producing a nonwoven fabric according to any one of claims 1 to 21, wherein,
and calendaring the nonwoven fabric obtained by blowing the hot air to the web.
23. The method for producing a nonwoven fabric according to claim 22, wherein,
the calendering is performed in multiple stages, and any of the calendering is performed under the following conditions, namely C1:
temperature: 25 ℃ of,
Line pressure: 20N/cm or more and 500N/cm or less,
And (3) roller: a pair of calender rolls are used, one of which is a metal calender roll and the other is a resin roll having a D hardness of 40 degrees to 100 degrees, the D hardness being defined in JIS K6253.
24. The method for producing a nonwoven fabric according to claim 23, wherein,
as the metal calender roll, a smooth calender roll subjected to mirror finishing or a calender roll to which fine irregularities are applied is used.
25. The method for producing a nonwoven fabric according to claim 23 or 24, wherein,
as the resin roller, a roller composed of a resin of hard rubber, silicone rubber, urethane rubber, NBR, or EPDM is used.
26. The method for producing a nonwoven fabric according to any one of claims 23 to 25, wherein,
The resin roll is used as the resin roll, wherein the D hardness is 70-95 degrees, and the D hardness is defined in JIS K6253.
27. The method for producing a nonwoven fabric according to any one of claims 23 to 26, wherein,
the calendaring is performed by pressing the fiber sheet on line at a pressure of 20N/cm or more and 300N/cm or less.
28. The method for producing a nonwoven fabric according to any one of claims 23 to 27, wherein,
and performing the calendaring process of at least one stage among the calendaring processes under the condition C1.
29. The method for producing a nonwoven fabric according to any one of claims 23 to 28, wherein,
the calendering process is performed in two stages, with the second stage of calendering process being performed under the conditions C1.
30. The method for producing a nonwoven fabric according to claim 29, wherein,
the line pressure of the calendering process of the first stage is made higher than that of the second stage.
31. The method for producing a nonwoven fabric according to claim 30, wherein,
the line pressure of the first stage of calendaring is set to be 50N/cm or more and 700N/cm or less, preferably 100N/cm or more and 300N/cm or less.
32. The method for producing a nonwoven fabric according to any one of claims 22 to 31, wherein,
The nonwoven fabric after the calendaring is processed so that the compression work WC is 1.2mN cm/cm 2 Above and 1.6 mN.cm/cm 2 The heat treatment or the calendaring process is performed in the following manner.
33. A nonwoven fabric produced by the method for producing a nonwoven fabric according to any one of claims 1 to 32.
34. The nonwoven fabric of claim 33, wherein,
the tensile strength of the nonwoven fabric in the longitudinal direction, that is, in the transport direction, is 10N/50mm or more and 100N/50mm or less, preferably 20N/50mm or more and 70N/50mm or less.
35. The nonwoven fabric according to claim 33 or 34, wherein,
the nonwoven fabric has a tensile strength in the width direction, i.e., in a direction perpendicular to the conveying direction, of 4N/50mm or more and 15N/50mm or less, preferably 5N/50mm or more and 12N/50mm or less.
36. The nonwoven fabric according to any one of claims 33 to 35, wherein,
the number of fibers per unit area of the nonwoven fabric that develop fuzzing is 20 or less, preferably 10 or less, and more preferably 0.
37. An absorbent article comprising the nonwoven fabric according to any one of claims 33 to 36 as a constituent member.
38. The absorbent article of claim 37, wherein,
The nonwoven fabric has a layer containing thermally fusible fibers having a fiber diameter of 15 [ mu ] m or less,
the nonwoven fabric is contained so that the layer-side surface is a skin contact surface.
CN202180097455.8A 2021-07-12 2021-07-12 Method for producing nonwoven fabric, nonwoven fabric produced by using same, and absorbent article comprising same as constituent member Pending CN117337346A (en)

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