AU2013321216A1

AU2013321216A1 - Nonwoven cloth

Info

Publication number: AU2013321216A1
Application number: AU2013321216A
Authority: AU
Inventors: Satoshi Mitsuno; Jun Okuda
Original assignee: Unicharm Corp
Current assignee: Unicharm Corp
Priority date: 2012-09-28
Filing date: 2013-09-20
Publication date: 2015-04-09
Anticipated expiration: 2033-09-20
Also published as: CN203700710U; EP2902537A1; KR102117135B1; EP2902537B1; KR20150060607A; CN103710883A; AU2013321216B2; US20150211157A1; JP5840100B2; JP2014070317A; EP2902537A4; CN103710883B; WO2014050762A1

Abstract

In order to address the problem of providing a nonwoven cloth provided with both improved softness and adequate thickness and specific volume, the present invention provides a nonwoven cloth having thermally fused composite fibers (F1, F2) that are mutually intersecting and overlapping, and a constricted thermally adhesive section (B1) in which the thermally fused composite fibers (F1, F2) are thermally fused in the intersecting region (R1); wherein the constricted thermally adhesive section (B1) has a recessed surface facing a center line (A1) extending in a direction (Z1) overlapping with the thermally fused composite fibers across the center (P1) of the intersecting region (R1), the distance between the thermally fused composite fibers (F1, F2) being larger than the sum of the radii of the thermally fused composite fibers, the thickness under a load of 3.0 gf/cm

Description

AB695-PCT -I1 DESCRIPTION Title of Invention: NONWOVEt1 is Technical Field [0001] The present invention relates to a nonwoven fabric. Background Art 10 [0002] A nonwoven fabric used as a component member, such as a top sheet, etc., of an absorbent article such as disposal diaper, sanitary napkin, etc., is usually formed into a strip form, is stored in the form of a wound roll, and is unwound from the roll for use. 15 [0003] If a nonwoven fabric is wound up in the form of a roll, the nonwoven fabric is compressed in the thickness direction and the bulkiness (thickness) of the nonwoven fabric is reduced, and the reduction in the bulkiness of the nonwoven fabric may result in the 20 decrease in the liquid absorption rate and the decrease in flexibility of the nonwoven fabric. [0004] As a method for restoring the bulkiness or a nonwoven fabric having a reduced bulkiness, a method in which hot air is applied to the nonwoven fabric by an 25 air-through method to restore the bulkiness of the nonwoven fabric has been known (Patent Literature 1). In this method, hot air is applied to the nonwoven fabric in the thickness direction thereof (perpendicular to the nonwoven fabric) 30 [0005] In addition, as a method for producing a nonwoven fabric, a method for forming a nonwoven fabric from an aggregate of fibers by applying a water vapor stream to the aggregate of fibers (Patent Literature 2). In this method, a water vapor stream is applied to an 35 aggregate of fibers in the thickness direction thereof (perpendicular to the fiber aggregate), and thereby the fibers are separated and a bridging structure (FIG. 4 of - 2 Patent Literature 2) is formed between the fibers. The bridging structure formed between the fibers improves the flexibility of a nonwoven fabric. Citations List 5 Patent Literature [0006] Patent Literature I: Japanese Unexamined Patent Publication No, 2004-137655 Patent Literature 2: Japanese Unexamined Patent 10 Publication No. 2009-177364 Summary of Invention Problems to Be Solved by the invention [0007] however, it is difficult to produce a nonwoven fabric having improved flexibility as well as sufficient 15 thickness and specific volume by the methods of Patent Literatures 1 and 2, since pressure is applied to a nonwoven fabric or an aggregate of fibers in the thickness direction thereof (i.e., the opposite direction to the thickness increasing direction) by hot air or a 20 water vapor stream. [0008] Therefore, an object of the present invention is to provide a nonwoven fabric having an improved flexibility as well as sufficient thickness and specific vol ume. 25 Means for Solving the Problems [0009] To overcome the above problems, the present invention is to provide a nonwoven fabric comprising heat-fusible conj ugate fibers intersecting and overlapping with each other and heat-fused constriction 30 parts at the intersection regions of the heat-fusible conjugate fibers, wherein when a virtual line extending in the overlapping direct-ion of the heat-fusible conjugate fibers through the center of an intersection region is defined as a center line, the heat-fused constriction parts have a surface which is recessed toward the center line, wherein the distance between the heat-fusible conjugate fibers that are heat-fused through a heat-fused constriction part is larger than the total of the fiber radius of each heat-fusible conjugate fiber, and wherein the nonwoven fabric has a thickness of 0. 5 to 3.0 mm under a load of 3.0 gf/cm 2 , and a specific volume 5 of 6 to 300 cm 3 /g. [0010] In a preferred embodiment (Embodiment 1) of the nonwoven fabric of the present invention, the nonwoven fabric has a plurality of heat-fused parts at the intersection regions of the heat-fusible conjugate fibers 10 intersecting and overlapping with each other, and wherein the proportion of the number of the heat-fused constriction parts to the total number of the heat-fused parts included in a predetermined. region of the nonwoven fabric is 1/10 to 9/10. 15 [0011] In a preferred embodiment (Embodiment 2) of the nonwoven fabric of the present invention, the heat fusible conjugate fibers have a fiber diameter of 10 to 30 Wi. Embodiment 2 may be combined with Embodiment 1. [0012] In a preferred embodiment (Embodiment 3) of the 20 nonwoven fabric of the present invention, wherein the heat-fusible conjugate fibers comprise a first component and a second component having a melting point lower than that of the first component, wherein the weight ratio of the second component to the first component (the second 25 component/the first component) is 4/6 to 8/2. Embodiment 3 may be combined with Embodiment 1 and/or Embodiment 2. [0013] In a preferred embodiment (Embodiment 4) of the non woven fabric of the present invention, the nonwoven fabric is obtained by a bulkiness restoration treatment 30 of a nonwoven fabric before bulkiness restoration, comprising heat-fused, heat-fusible conjugate fibers, wherein the bulkiness restoration treatment comprises a step or providing a heating chamber having an inlet and an outlet, and a step of, while conveying the nonwoven 35 fabric before bulkiness restoration so as to enter into the heating chamber through the inlet, to proceed through the heating chamber, and then to exit from the heating - 4 chamber through the outlet, feeding a heated fluid at a velocity higher than the conveyance velocity of the nonwoven fabric before bulkiness restoration so as to enter into the heating chamber through one of the inlet 5 and outlet, to proceed through Lhe heating chamber while contacting the nonwoven fabric, and then to exit from the heating chamber through the other of the inlet and outlet. Embodiment 4 may be combined with one or two or more of Embodiments 1 to 3. 10 [0014] In a preferred embodiment (Embodiment 5) of the nonwoven fabric of Embodiment 4, the nonwoven fabric before bulkiness restoration is an air-through nonwoven fabric obtained by an air-through treatment of a web comprising heat-fusible conjugate fibers to heat-fuse the 15 heat-fusible coniugate fibers. [0015] In a preferred embodiment (Emrbodiment 6) of the nonwoven fabric of Embodiment 4 or 5, the heated fluid enters into the heating chamber through the inlet and exits from the heating chamber through the outlet. 20 Embodiment 6 may be combined with Embodiment 4 and/or Embodiment 5. [0016] In a preferred embodiment (Embodiment 7) of the nonwoven fabric according to any one of Embodiments 4 to 6, the nonwoven fabric before bulkiness restoration is 25 conveyed through the heating chamber without being supported. Embodiment 7 may be combined with one or two or more of Embodiments 4 to 6. [0017] In a preferred embodiment (Embodiment 8) of the nonwoven fabric according to any one of Embodiments 4 to 30 7, the heating chamber is defined by two walls that extend from the inlet to the outlet and are separated from each other, and the nonwoven fabric before business restoration is conveyed within the heating chamber so that both surfaces of the nonwoven fabric before 35 bulkiness restoration respectively continue to face the walls. Embodiment 8 may be combined with one or two or more of Embodiments 4 to 7.

- 5 Advantageous Effects of Invention [0018] A nonwoven fabric having an improved flexibility as well as sufficient thickness and specific volume is provided by the preset invention. -5 Brief Descr.iption of Drawings [0019] FIG. 1(a) is a plan view of heat-fusible conjugate fibers intersecting and overlapping with each other, in which one of: the fibers is located upside and the other 10 fiber is located downside, when viewed in plan view, and FIG. 1(b) is a cross-sectional view along line I-I in FIG. 1(a). FIG. 2(a) is a plan view of heat-fusible conjugate fibers intersecting and overlapping with each other, in 15 which one of the fibers is located upside and the other fiber is located downside, and FIG. 2(b) is a cross sectional view along line IT-Il in FIG. 2(a). FIG. 3 is an overall view of the bulkiness restoration system according to one embodiment. 20 FIG. 4 is an enlarged cross-sectional view of the heating chamber. FIG. 5 is a view of an end "'ace of the hearing chamber. FIG. 6 is a view showing another embodiment of the 25 bulkiness restoration system. FIG. 7 is a view showing still another embodiment of the bulkiness restoration system. FIG. 8 is an overall view of the bulkiness restoration system of- a comparative example. 30 FIGS. 9(a) to (c) are electron microscope photographs of a nonwoven fabric before bulkiness restoration (before conveyance to the bulkiness restoration system). FIGS. 10(a) to (c) are electron microscope 35 photographs of a nonwoven fabric subjected to the bulkiness restoration treatment under the conditions of Example 1.

- f) FIGS. 11(a) to (c) are electron microscope photographs of a nonwoven fabric subjected to the bulkiness restoration treatment under the conditions or Example 2. FIGS. 12(a) to (c) are electron microscope photographs of a nonwoven fabric subjected to the bulkiness restoration treatment under the conditions of Comparative Example 1. FIGS. 13(a) to (c) are electron microscope 10 photographs of a nonwoven fabric subjected to the bulkiness restoration treatment under the conditions of Comparative Example 2. FIGS. 14(a) to (c) are electron microscope photographs of a nonwoven fabric subjected to the 15 bulkiness restoration treatment under the conditions orf Comparative Example 3. Mode for Carrying Out the Invention [0020] The nonwoven fabric of the present invention will be described in detail below. 20 The nonwoven fabric of the present invention comprises heat-fusible conjugate fibers intersecting and overlapping with each other and heat-fused constriction parts at the intersection regions of the heat-fusible conjugate fibers. 25 [0021] The nonwoven fabric of the present- invention has an improved flexibility, since the heat-fusible conjugate fibers are heat-fused through the heat-fused constriction parts. The flexibility of the nonwoven fabric can be evaluated on the basis ofr for example, the 30 compression properties of the nonwoven fabric. The compression properties of nonwoven fabrics include, for example, compression energy WC per 1 cm 2 of nonwoven fabric (N -/r2) and compression resilience RC (%), measured in KES compression test. The WC value 35 represents compression deformation properties, and the greater the WC value, the higher the compression deformation properties. In addition, the RC value represents compression recovery properties, and an RC value closer to 100% indicates higher compression recovery properties. In the KES compression test, for example, an automated compression tester KES-FB3 5 manufacture by Kato Tech Corp. can be used. The WC value is preferably 0.5 N -/m2 or more, and more preferably 1.0 N- Im/m 2 or more. The RC value is preferably 30% or more, and more preferablv 40% or more. [0022] Although the nonwoven fabric of the present 10 invention comprises many intersection regions of the heat-fusible conjugate fibers, the heat-fusible conjugate fibers are not needed to be heat-fused at all of the intersection regions, and the heat-fusible conjugate fibers may be heat-fused at some intersection regions. 15 [0023] In the nonwoven fabric of the present invention, the intersection regions of the feat-fusible conjugate fibers are regions where the heat- fusible conjugate fibers are intersecting and overlapping with each other, in which one of the fibers is located upside 20 and the other fiber is located downside when viewed in plan view (see FIG. 1(a)), and are regions extending between the heat-fusible conjugate fibers in the overlapping direction (vertical direction) of the heat fusible conjugate fibers in a cross sectional view (see 25 FIG. 1(b)). [0024] The nonwoven fabric of the present invention has a plurality of heat-fused parts at the intersection regions of the heat-fusible conjugate fibers intersecting and overlapping with each other. Although the heat-fused 30 parts comprise a portion existing within an intersection region o-f the heat-fusible conjugate fibers, it is not necessary that the entire of the heat-fused part exists within the intersection region of the heat-fusible conjugate fibers, and the heat-fused. parts may comprise a 35 portion extending outside the intersection region of the heat-fusible conjugate fibers. [0025] Some or all of the heat-fused parts included i - 8 the nonwoven fabric of the present invention are heat fused constriction parts. The proportion of the number of the heat-fused constriction parts to the total number of the heat-fused parts included in a predetermined 5 region of the nonwoven fabric is not particularly limited, but is preferably 1/10 to 9/10, and more preferably 2/8 to 8/10. The proportion of the number of the heat-fused constriction parts to the total number of the heat-fused parts can be determined by, for example, 10 observing a nonwoven fabric with a microscope such as a scanning electron nicroscope and counting the number of the total number of the heat-fused parts and the heat fused constriction parts within the visual field of the microscoe. The magnification of the microscope at the 15 time of observation is typically 100 to 500 times, and preferably 200 to 400 times. [0026] When a virtual line extending in the overlapping direction of the heat-fusible conjugate fibers through the center of an intersection region of 20 the heat-fusible conjugate fibers is defined as a center line, the heat-fused constriction parts have a surface which is recessed toward the center line. [0027] An embodiment of the heat-fused constriction parts will be explained below with ref-erring to heat 25 fusible conjugate fibers intersecting perpendicularly with each other as an example. For convenience of explanation, the intersection angle of the heat-fusible conjugate fibers is perpendicular, but the intersection ang e of the heat-fusible fibers should not be limited to 30 vertical. [0028] FIG. 1(a) is a plan view of heat-fusible conjugate fibers Fl, F2 intersecting and overlapping with each other, in which heat-fusible conjugate fiber F1 is located side and heat-fusible conjugate fiber F2 is 35 located downside. FIG. 1(b) is a cross sectional view along line I-I in FIG. 1(a). The direction of line I-I in FIG. 1(a) coincides with the direction of axis line L2 - 9 of heat-fusible conjugate fiber F2 in FIG. 1(a). [0029] As shown in FIG. 1(a), heat-fusible conjugate fiber F1 extends along axis line Li, heat-fusible conjugate fiber F2 extends along axis line L2, and heat 5 fusible conjugate fibers F1, F2 intersect perpendicularly with each other. [0030] in FIG (a), although axis line LI and axis line L2 are represented as straight lines, axis line Ll and axis line L2 should not be limited to straight lines 10 and may be curved lines. When focused on a minute section where heat-fusible conjugate fibers Fl, F2 intersect with each other, axis line Il and axis line L2 can be approximated to substantially straight lines as shown in FIG. 1 (a) 15 [0031] As shown in FIGS. 1(a) and (b), intersection region RI of heat-fusible conjugate fibers F1, F2 is a region where heat-fusible conjugate fibers F1, F2 overlap with each other when viewed in plan view and which extends between heat--fusible coniugate fibers F1, F2 in 20 overlapping direction ZI (vertical direction) of heat fusible conjugate fibers F1, F2 when viewed in cross sectional view. [0032] As shown in FIG. 1(a), center P. of intersection region RI coincides with the intersection 25 point of axis line L1 and axis line L2, when viewed in plan view. [0033] As shown in FIG. 1(b), heat-fusible conjugate fibers Fl, F2 are heat-fused with each other at heat fused constriction part Bl in intersection region RI. In 30 this embodiment, the entire of heat-fused constriction part B1 is formed inside intersection region R1, but may comprise a portion extending outside intersection region R1. [0034] As shown in FIG. 1(b), when a virtual line 35 extending in overlapping direction ZI (vertical direction) of heat-fusible conjugate fibers Fl, F2 through center P1 of intersection region R1 of heat- - 10 fusible conjugate fibers F1, F2 is defined as center line Al, heat-fused constriction part B1 has a surface which is recessed toward center line Al. Center line Al coincides with the vertical line drawn from axis line EL 5 of heat-fusible conjugate fiber F1 to axis Line L2 of heat-fusible conjugate fiber F2 in intersection region R1 of heat-fusible conjugate fibers Fl, F2. [0035] The outer peripheral surface of heat-fused constriction part B12 may be partly recessed toward center 10 line Al, and almost entire of the outer peripheral surface is preferably recessed toward center line Al. The outer peripheral surface of heat-fused constriction part. B1 may have a part where cracks have been generated, [0036] In the nonwoven fabric of the present 15 invention, the distance between the heat-fusible conjugate fibers that are heat-fused through a heat-fused constriction part is larger than the sum of the fiber radius of each heat-fusible conjugate fiber. The joining strength between the heat -fusible conjugate fibers 20 through the heat-fused constriction part decreases with the increase in the distance between the heat-fusible conjugate fibers that are heat-fused through the heat fused constriction part, and thereby the flexibility of the nonwoven fabric is improved. In addition, the 25 thickness and specific volume (void volume) of the nonwoven fabric increase with the increase in the distance between the heat-IFusible conjugate fibers that are heat-fused through the heat-fused constriction part. In the above embodiment, the distance (r3) between heat 30 fusible conjugate fibers Fl, F2 that are heat-fused through heat-fused constriction part Bi is larger than the sum of the fiber radii (r- + r2) of heat-fusible conjugate fibers Fl, F2, as shown in FIG. I (b). [0037] The heat-fused parts other than the heat-fused 35 constriction parts included in the nonwoven fabric of the present invention include, for example, heat-fused bulge parts having a surface protruding toward the direction - 11 away from the center line, wherein a virtual line extending in the overlapping direction of the heat fusible conjugate fibers F1, F2 through the center of an intersection region of the heat-fusible conjugate fibers 5 is defined as the center line. [0038] An embodiment of the heat-fused bulge parts will be explained below with referring to heat-fusible conjugate fibers intersecting perpendicularly with each other as an example. For convenience of explanation, the 10 intersection angle of the heat-fusible conjugate fibers is perpendicular, but the inLersection angle of the heat fusible fibers should not be limited to vertical. [0039] FIG. 2(a) is a plan view of heat-fusible conjugate fibers F3, F4 intersecting and overlapping with 15 each other, in which heat-fusible conjugate fiber F3 is located upside and heat-fusible conjugate fiber F4 is located downside. FIG. 2 (b) is a cross sectional view along line II-Il in FIG. 2(a). The direction of line II II in FIG. 2(a) coincides with the direction of axis line 20 L4 of heat-fusible conjugate fiber F4 in FIG. 2(a). [0040] As shown in FIG. 2(a), heat-fusible conjugate fiber F3 extends along axis line L3, heat-fusible conjugate fiber F4 extends along axis line L4, and heat fusible conjugate fibers F3, F4 intersect perpendicularly 25 with each other. [0041] In FIG. 2(a), although axis line L3 and axis line L4 are represented as straight lines, axis line P3 and axis line L4 should not be limited to straight lines and may be curved lines. When focused on a minute 30 section where heat-fusible conjugate fibers F3, F4 intersect with each other, axis line L3 and axis line L4 can be approximated to substantially straight lines as shown in FIG. 2 (a). [0042] As shown in FIGS. 2(a) and (b), intersection 35 region R2 of heat-fusible conjugate fibers F3, F4 is a region where heat-fus-ible conjugate fibers F3, F4 overlap with each other when viewed in plan view and which - 12 extends between heat-fusible conjugate fibers F3, F4 in overlapping direction Z2 (vertical direction) of heat fusible conjugate fibers F3, F4 when viewed in cross sectional view. 5 [0043] As shown in FIG. 2(a), center P2 of intersection region R2 coincides with the intersection point of axis line 13 and axis line L4, when viewed in plan vew. [0044] As shown in FIG. 2(b), heat-fusible conjugate 10 fibers F3, F4 are heat-fused with each other at heat fused bulge part B2 in intersection region R2. In this embodiment, heat-fused bulge part B2 comprises a portion existing inside intersection region R2 and a portion extending outside intersection region R2, but the entire 15 of heat-f-used bulge part B2 may exist inside intersecion region R2. [0045] As shown in FIG. 2 (b), when a virtual line extending in overlapping direction Z2 (vertical direction) of heat-fusible conjugate fibers F3, F4 20 through center P2 of intersection region R2 of heat fusible conjugate fibers F3, F4 is defined as center line A2, heat-fused bulge part B2 has a surface protruding toward the direction away from center line A2. Center line A2 coincides wit-h the vertical line drawn from axis 25 line L3 of heat-fusible conjugate fiber F3 to axis line L4 of heat-fusible conjugate fiber F4 in intersection region R2 of heat-fusible conjugate fibers F3, F4. [0046] The outer peripheral surface of heat-fused bulge part B2 may partly protrude toward the direction 30 away from center line A2, and almost entire of the outer peripheral surface is preferably protruding away from center line A2. The outer peripheral surface of heat fused constriction part B2 may have a part where cracks have been generated. 35 [0047] As shown in FIG. 2 (b) , heat-fusible conjugate fibers F3, F4 are biting into each other, and accordingly distance (r3) between heat-fusible conjugate fibers F3, - 13 F4 is smaller than the sum of the fiber radii (rl + r2) of heat-fusible conjugate fibers F3, F4. [0048] Thy nonwoven fabric of the present invention has a thickness (under a load of 3.0 gf/cm 2 ) of 0.5 to 3.0 5 mm, and preferably 0.7 to 3.0 tm, and a specific volume of 6 to 300 cm 3 /g, and preferably 12 to 200 cm 3 /g. Accordingly, the nonwoven fabric of the present invention has sufficient thickness and specific volume. When the nonwoven fabric of the present is used as a top sheet of 10 an absorbent article, the range less than the above Lower limits of the thickness and specific volume may result in decrease in liquid permeability and thereby easily develop stickiness, whereas the range more than the above upper limits result in increase in -the thickness of the 15 entire absorbent article and thereby easily provides uncomfortable feeling during wearing of the absorbent article. [0049] The thickness and specific volume vary depending on the proportion of the heat-fused 20 constriction part to the total number of the heat-fused parts, the form of the heat-fused constriction parts, the distance between the heat-fusible conjugate fibers that are heat-fused through a heat-fused constriction part, etc. The nonwoven fabric of the present invention can be 25 produced by bulkiness restoration treatment o1 a nonwoven fabric before bulkiness restoration, comprising heat fused, heat-fusible conjugate fibers, as described below, and the control of- the conditions of bulkiness restoration treatment allows adjustment in the proportion 30 of the heat-fused constriction part to the total number of the heat-fused parts, the form of the heat-fused constriction parts, the distance between the heat-fusible conjugate fibers that are heat-fused through a heat-fused constriction parts, etc., and therefore it is possible to 35 adjust the thickness and specific volume of the nonwoven fabric to desired ranges. The thickness (mn) of the nonwoven fabric is measured with a thickness gauge - 14 (THICKNESS GAUGE UF-60 manufactured by Daiei Kagaku Seiki Manufacturing Co., Ltd.) while applying a load of 3. 0 gf/cm 2 to the nonwoven fabric. Ten different points of the nonwoven fabric are measured for thickness in the 5 same manner, and an average value of ten measurement values is determined as the thickness of the nonwoven fabric. The basis weight of the nonwoven fabric is measured .in accordance with JIS L 1906 5.2. The density of the nonwoven fabric is calculated out on the basis of. 10 the following formula: Density (gcm 3 ) of nonwoven fabric = basis weight (g/m 2 ) of nonwoven fabric/thickness (mm) of nonwoven fabric x 10~3, and the specific volume of the nonwoven fabric is 15 calculated out as an inverse of the density (g/m) of the nonwoven fabric. [0050] The basis weight of the nonwoven fabric of the present invention is not particularly limited, but is preferably 10 to 80 g/m2, and more preferably 15 to 60 20 g/m 2 . [0051] The heat-fusible conjugate fibers included in the nonwoven fabric of the present invention are not particularly limited as long as they are capable of developing heat-fusible properties. The heat-fusible 25 conjugate fibers include, for example, two---component composite fibers comprising a first component (hereinafter referred to as "high-melting point component") and a second component (hereinafter referred as "low-meiting point component") having a melting point 30 lower than that of the first component, wherein the second component exists on at least a part of the fiber surface continuously along the lengthwise direction. The component which develops heat-fusible properties is mainly the low-melting point component. The heat-fusible 35 conjugate fibers may be composite fibers comprising three or more components naving different melting points or softening points. The form of the heat-fusible conjugate - 15 fibers includes, for example, core-sheath type (concentric type, eccentric type, etc.), island-sea type, split-type, side-by-side type, etc., any type of conjugate fibers may be used. In the case of core-sheath 5 type conjugate fibers, the sheath component and core component can be comprised of a low-melting point component and a high-melting point component, respectively. The heat-fusible conjugate fibers are preferably those having been subjected to a stretching 10 treatment at the stage of raw material (prior to being used for the production of the nonwoven fabric). [0052] The types of: the high-melting point component and low-melting point component are not particularly limited as long as they have a fiber-forming ability. 15 The high-melting point component and low-melting point component are generally synthetic resins. The high melting point component includes, for example, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc., and the low 20 melting point component includes, for example, polyethylenes such as high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), etc., ethylene propylene copolymer, polystyrene, polypropylene (PP), copolymerized 25 polyesters, etc. For example, in the case of core-sheath type conjugate fibers, the sheath component (low-melting point component) when the core component (high-melting point component) is PP, includes, for example, polyethylenes such as HOPE, LDPE, LLDPE, etc., ethylene 30 propylene copolymer, polystyrene, etc., and the sheath component (low-melting point component) when the core component (high-melting point component) is PET, PBT, etc., includes, for example, PP, copolymerized polyesters, etc. 35 [0053] The heat-fusible composite fibers included in the nonwoven fabric of the present invention preferably contain a low-melting point component in an amount more - 16 than that of the high-melting point component, and the weight ratio of the low-melting point component to the high-melting point component (low-melting point component/high-melting point component) is preferably 4/6 5 to 8/2, and more preferably 5/5 to 7/3. This ensures heat-fusing by an air-through method, and thereby can effectively Prevent the surfaces of the air-through nonwoven fabric after bulkiness restoration from fluffina. The weight ratio of the low-melting point 10 component/high-melting point component can be calculated on the bas-is of the cross-sectional areas of the high melting point component and low-melting point component determined by observing the cross section of the heat fusible conjugate fibers as well as on the basis of the 15 densities of the high-melting point component and low melting point component. [0054] The difference in melting point between the high-melting point component and low-melting point component is preferable y 20*C, and more preferably 254C. 20 This feature results in the increase in difference in orientation, crystallinity, etc., of each component, and thereby improves the nonwoven fabric forming properties. The melting points can be measured as a melting peak temperature determined by thermal analysis on a finely 25 cut fiber sample using a differential scanning calorimeter (for example, DSC 6200 manufactured by Seiko Instruments Inc.) at a heating rate of 104C/min. If it is not possible to measure a melting point clearly, softening point may be used in place of melting point. 30 [0055] The fiber diameter of the heat-fusible conjugate fibers included in the nonwoven fabric of the present invention is not particularly limited, but is preferably 10 to 30 pm, and more preferably 15 to 25 pm, in view of decreasing the rough feeling of the surface. 35 The fiber diameter of the heat-fusible conjugate fibers can be measured by, for example, observing the nonwoven fabric with a microscope such as a scanning electron microscope, etc. [0056] The fineness of the heat-fusible conjugate fibers included in the nonwoven fabric is not 5 particularly limited, but is preferably 1 to 6 dtex when the nonwoven fabric is used in the top sheet of an absorbent article. If the fineness is less than 1 dtex, the nonwoven fabric tends to reduce its air-permeability and liquid permeability due to the reduction in the 10 thickness of the nonwoven fabric resulting from the decrease in the strength of the conjugate fibers, whereas, if the fineness is more than 6 dtex, the nonwoven fabric tends to reduce its touch feeling due to the increase in the strength of the conjugate fibers. 15 [0057] The amount of the heat-fusible conjugate fibers included in the nonwoven fabric of the present invention is preferably 20 to 100 wt%, and more preferably 30 to 100 wt%, on the basis of the total of the fibers that form the nonwoven fabric. 20 [0058] The nonwoven fabric of the present invention may comprises, in addition to the heat-fusible conjugate fibers, the other fibers (for example, monofilaments). The other fibers include, for example, natural fibers (wool, cotton, etc.), regenerated fibers (rayon, acetate, 25 etc.), inorganic fibers (glass fibers, carbon fibers, etc.), synthetic fibers (polyethylene fibers, polypropylene fibers, polyester fibers, acryl fibers, etc.). Incorporation of the ot-her fibers can imparts the nonwoven fabric with the functions of the other fibers 30 (for example, in the case of cotton, moisture absorbing properties; and in the case of synthetic fibers, air permeability, etc.). In addition, the nonwoven fabric of the present invention may be incorporated with hollow type fibers; profiled fibers such as flat fibers, Y 35 shaped fibers, C-shaped fibers, etc.; latent crimping or actually crimped three-dimensionally crimp fibers; split fibers split by a physical load such as water stream, - I8 heat, embossing, etc. [0059] When the nonwoven fabric of the present invention comprises fibers other than the heat-fusible conjugate fibers, the content of the fibers other than 5 the heat-fusible conjugate fibers is preferably 80 wt% or less, and more preferably 70 wt% or less on the basis of the total of the fibers that form the nonwoven fabric. [0060] The heat-fusible conjugate fibers included in the nonwoven fabric may be imparted with a three 10 dimensional crimped shape. The three-dimensional crimped shape includes, for example, a zigzag shape, and a Omega shape, a spiral shape, etc. The method for imparting a three-dimensional crimped shape includes, for example, mechanical crimping, shaping by heat shrinking, etc. 15 Mechanical crimping can be controlled by the peripheral speed difference in line speed, heat, pressurization, etc., with respect to continuous linear fibers after spinning, and the greater the number of crimps per unit length of the crimped fibers, the greater the buckling 20 strength of the fibers under external pressure. The number of crimps is typically 5 to 35 per inch, and preferably 15 to 30 per inch. Heat shrinking can provide a three-dimensional crimping by using the difference in heat shrinking resulting from the melting temperature 25 difference. [0061] When the nonwoven fabric comprises latent crimping fibers and/or actually crimped fibers, even if the fiber orientation primarily aligns to the planar direction, the fiber orientation partially aligns to the 30 thickness direction. Accordingly, the buckling strength of the fibers in the thickness direction is improved, and thereby the nonwoven fabric is less likely to decrease the bulkiness thereof even if an external force is applied to the nonwoven fabric. In addition, when the 35 heat-fusible conjugate fibers are imparted with a spiral shape, the nonwoven fabric readily restore the bulkiness when the external force to the nonwoven fabric is - 19 released. The latent crimping fibers and/or actually crimped fibers included in the nonwoven fabric of the present invention may be heat-fusible conjugate fibers having imparted With a three-dimensionally crimped shape 5 or may be fibers other than heat--fusible conjugate fibers. [0062] The nonwoven fabric of the present invention may be those subjected to a hydrophilizing treatment. Hydrophilized nonwoven fabrics can preferably be used as 10 a liquid-permeable top sheet for absorbent articles, since when they contact hydrophilic excrement (such as urine, sweat, feces, etc.), they easily transmit the excrement within the absorbent article without leaving the excrement on the surface thereof. The hydrophilizing 15 treatment includes, for example, a treatment with a hydrophilizing agent, kneading a hydrophili- zing agent into the constituent fibers of the nonwoven fabric, coating a surfactant to the nonwoven fabric, etc. [0063] The fibers which constitute the nonwoven fabric 20 of the present invention may contain an inorganic filler such as titanium oxide, barium sulfate, calcium carbonate, etc., to increase whitening properties. In the case of core-sheath type fibers, the core component may contain an inorganic filler, or the sheath component 25 may contain an inorganic filler. [0064] The nonwoven fabric of the present invention may have a textured structure on a surface thereof. The presence or absence of the textured structure can be confirmed by, for example, in the cross-sectional shape 30 in the direction (CD direction) perpendicular to the conveyance direction (MD direction) . For example, the nonwoven fabric of the present invention may have a plurality of convex portions the interiors of which are comprised of heat-fusible conjugate fibers oriented 35 relatively to the thickness direction of the nonwoven fabric and a plurality of concave portions comprised of heat-fusible conjugate fibers oriented in the planar - 20 direction of the nonwoven fabric. In the textured structure, the concave portions have a thickness smaller than that of the convex portions. When the surface of the nonwoven fabric is textured, the contact area with 5 the skin can be decreased, and therefore such a nonwoven fabric is suitable as a top sheet for absorbent articles. [0065] The nonwoven fabric of the present invention can be applied in various fields utilizing bulkiness, compression deformability, compression restorability, 10 etc. The nonwoven fabric of the present invention can be suitably used as a top sheet, a second sheet (a sheet disposed between a top sheet and an absorbent body), a back sheet, and a leakage prevention sheet of absorbent articles in the field of disposal hygiene articles such 15 as sanitary napkins, disposable diapers, etc. In addition, the nonwoven fabric of the present invention can be suitably used as a personal cleaning sheet, a skin care sheet, an article wiper, etc. [0066] The nonwoven fabric of the present invention 20 can be produced by bulkiness restoration treatment of the nonwoven fabric before bulkiness restoration, comprising heat-fused, heat-fusible conjugate fibers. [0067] A preferred bulkiness restoration treatment comprises a step of providing a heating chamber having an 25 inlet and an outlet, and a step of, while conveying the nonwoven fabric before bulkiness restoration so as to enter into the heating chamber through the inlet, to proceed through the heating chamber, and then to exit from the heating chamber through the outlet, feeding a 30 heated fluid at a velocity higher than the conveyance velocity of the nonwoven fabric before bulkiness restoration so as to enter into the heating chamber through one of the inlet and outlet, to proceed through the heating chamber while contacting the nonwoven fabric, 35 and then to exit from the heating chamber through the other of the inlet and outlet. Embodiment 4 may be combined with one or two or more of Embodiments 1 to 3.

- 21 [0068] The nonwoven fabric before bulkiness restoration is preferably an air-through nonwoven fabric obtained by air-through treatment of a web comprising heat-fusible conjugate fibers to heat-fuse the heat 5 fusible conjugate fibers. In the bulkiness restoration treatment, it is preferable that the heated fluid enters into the heating chamber through the inlet and exits from the heating chamber through the outl et, and that the nonwoven fabric before bulkiness restoration is conveyed 10 through the heating chamber without being supported, that the heating chamber is defined by two walls that extend from the inlet to the outlet and are separated from each other, and the nonwoven fabric before bulkiness restoration is conveyed within the heating chamber so 15 that both surfaces of the nonwoven fabric before bulkiness restoration respectively continue to face the walls. [0069] An embodiment of the method for producing the nonwoven fabric of the present invention will be 20 explained below, on the basis of the drawings. This embodiment employs bulkiness restoration system I for restoring the bulkiness of nonwoven fabric F, as shown in FIG. 3, [0070] Nonwoven fabric F is one comprising heat-fused, 25 heat-fusible conjugate fibers. The nonwoven fabric includes, for example, an air-through nonwoven fabric, point-bond nonwoven fabric, spunbond nonwoven fabric, etc., and is preferably an air-through nonwoven fabric. [0071] Air-through nonwoven fabrics are nonwoven 30 fabrics obtained by passing hot air through a web comprising heat-fusible conjugate fibers to heat-fuse the intersections of the heat-fusible conjugate fibers. The web comprising heat-fusible conjugate fibers can be formed by a well -known web forming process using a 35 carding machine, etc. The web forming process includes, for example, a process in which short fibers are conveyed by an air flow and are deposited on a net (air-laid - 22 method), etc. The web thus formed is a fiber aggregate before forming a nonwoven fabric and is not subjected to a treatment (for example, heat-fusing treatment in airthrough method, calendering method, etc.) which will be 5 applied to a nonwoven fabric production process, and therefore is in the form In which the fibers are extremely loosely entangled with each other. The airthrough treatment for the web comprising heat-fusible conjugate fibers, can be carried out using, for example, 10 a hot--air blowing apparatus. In an air-through treatment, a hot air heated to a predetermined temperature (for example, 120 to 1604C) is blown to a web and is passed through the web, and thereby heat-fusing together the intersections of heat-fusible conjugate 15 fibers in the web. The nonwoven fabric produced by such an air-through treatment includes, for example, nonwoven fabrics comprising mainly of: core-sheath type conjugate fibers in which the sheath component is a high-density polyethylene and the core component is polyethylene 20 terephthalate and having a fiber length of 2.0 to 100 mm, and preferably 35 to 65 mm, and a fineness of 1.1 to 8.8 dtex, and preferably 2.2 to 5.6 dtex. [0072] Blowing hot air is an example of heat treatment for heat-fusing together the intersections of the heat 25 fusible conjugate fibers in a web. The heat treatment is not particularly limited as long as it can heat the heat fusible conjugate fibers (low melting point component) to the melting point or more. The heat treatment can be carried out using hot air as well as a heat medium such 30 as microwave, steam, infrared radiation, etc. [0073] Nonwoven fabric F may have a texture on a surface thereof. The texture can be imparted to the surface of nonwoven fabric F by, for example, blowing hot air to the web, thereby allowi-ng the formation of a 35 plurality of convex portions the interiors of which are comprised of heat-fusible conjugate fibers oriented to the thickness direction of the nonwoven fabric and a - 23 plurality of concave portions comprised of heat-fusible conjugate fibers oriented in the planar direction of the nonwoven fabric. [0074] As shown in FIG. 3, nonwoven fabric F is wound 5 around roll R, resulting in decrease in bulkiness of nonwoven fabric F. Accordingly, to restore the bulkiness of nonwoven fabric F, bulkiness restoration system 1 is used. [0075] Nonwoven fabric F comprises a plurality of 10 heat-fused parts at the intersection regions of the heat fusible conjugate fibers intersecting and overlapping with each other. The plurality of heat-fused parts included in nonwoven fabric F are mainly heat-fused bulge parts shown in FIG. 2. Then, some or all of the heat 15 fused bulge parts as shown in FIG. 2 change into heat fused constriction parts as shown in FIG. 1 during the bulkiness restoration treatment with bulkiness restoration system 1. That is, during the bulkiness restoration treatment with bulkiness restoration system 20 1, the heat-fused bulge parts soften or melt, and the heat-fusible conjugate fibers heat-fused with each other via the heat-fused bulge parts are slightly spaced away from each other, and consequently the heat-fused bulge parts slightly extend and change into heat-fused 25 constriction parts. Particularly, since, in the bulkiness restoration treatment with bulkiness restoration system 1, hot air flows in parallel to nonwoven fabric F before bulkiness restoration and the velocity of the hot air is higher than the velocity of 30 the nonwoven fabric, a turbulent flow is generated within bulkiness restoration system 1, and thereby promoting heat transfer. In addition, since a force is not applied to the constituent fibers of nonwoven fabric F in the same direction but is applied to the constituent fibers 35 along the fiow of air, the heat-fused bulge parts slightly extend and change into heat-fused constriction parts.

- 24 [0076] The joining strength of the heat-fusible conjugate fibers by the heat-fused parts decreases due to the change in shape of the hea-fused parts from a bulge from to a constriction form. Due to the change in shape 5 of the heat-fused parts from a bulce form to a constriction form, the degree of freedom of the fibers to compression deformation is increased., and thereby making it easier for the fibers to move. Accordingly, nonwoven fabric F subjected to the bulkiness restoration treatment 10 has excellent compression deformation properties. In addition, since heat easily transfers to the heat-fusible conjugate fibers during bulkiness restoration treatment, the resins which constitute the heat-fusible conjugate fibers are oriented by the heat, and therefore have 15 improved crystallinity. Therefore, in nonwoven fabric F subjected to the bulkiness restoration treatment, the initial strength of fibers is improved, and accordinglv the fibers are less likely to deform by initial deformation, and thereby the shape retention properties 20 are improved. Therefore, nonwoven fabric subjected to the bulkiness restorat ion treatment exhibits excellent compression restoration properties. [0077] The basis weight of nonwoven fabric F is substantial ally constant before and after bulkiness 25 restoration treatment. The basis weight to the nonwoven fabric is, for example, 10 to 80 g/m 2 (particularly 15 to 60 g/m 2 ) The thick ness of nonwoven fabric F is increased by the bulkiness restoration treatment. The thickness (under a load of 3.0 gf/cm 2 ) of the nonwoven fabric F is 30 increased, for example, from 0.2 to 0.6 mm (particularly 0.3 to 0.5 mm) (before bulkiness restoration treatment) to 0.5 to 3.0 mm particularlyy 0.7 to 3.0 mm). The specific volume of nonwoven fabric F is increased by the bulkiness restoration treatment. The specific volume of 35 nonwoven fabric F is increased, for example from 2.5 to 50 cm/g (particularly 5 to 33 cm 3 /gj to 6 to 300 cm 3 /g (particularly 12 to 200 cm3/g).

- 25 [0078] As shown in FIG. 3, bulkiness restoration system 1 comprises conveyor 2 which conveys nonwoven fabric F in the form of a strip while unwinding it from a roll R. Conveyor 2 comprises two roller pairs 2a, 2b. 5 Each roller pair 2a, 2b comprises a pair of rollers which rotate in opposite directions each other. When these rollers are rotated, nonwoven fabric F is conveyed. In this embodiment, nonwoven -fabric F is conveyed in the machine direction MD which substantially coincides with 10 the horizontal direction so that one surface and the other surface generally face upward and downward, respectively. [0079] As shown in Fig. 3, bulkiness restoration system 1. further comprises heater 3 for heating nonwoven 15 fabric F to be conveyed with a fluid. Heater 3 comprises fluid source 3a, feed pipe 3b which is connected to an outlet of fluid source 3a, nozzle 3c which is connected to an outlet of feed pipe 3b, flowmeter 3ba which is arranged in feed pipe 3b, regulator 3d which is arranged 20 in feed pipe 3b downstream of flowmeter 3ba, electric heater 3e which is arranged in feed pipe 3b downstream ot regulator 3d, and housing 3f. Nozzle 3c has, f-or example, an elongated rectangular shaped outlet. [0080] In this embodiment, the fluid is air, and fluid 25 source 3a is a compressor. When compressor 3a is operated, air flows through feed pipe 3b. Flowmeter 3ba detects the flow rate of air which flows through feed pipe 3b and outputs an air flow rate in the form of a quantity under standard condition (O'C, 1 atm). The air 30 pressure in feed pipe 3b is reduced by regulator 3d from, for example, 0.6 MPaG to 3 MPaG to 0.01 MPaG. The air is then heated by electric heater 3e. The heated air then flows out from nozzle 3c. The flow rate of air flown out from the nozzle 3c is, for example, 2380 L/min. (2.38 35 m 3 /min., standard condition). Air is heated by electric heater 3e to, for example, 100 to 200*C so that the temperature of the air flown out from nozzle 3c is, for - 26 example, 70 to 160*C. The temperature of the air flown out from nozzle Sc can be detected by a temperature sensor arranged in vicinity of the outlet of- nozzle 3c. [0081] As shown in FIGS. 4 and 5, housing 3f comprises 5 upper wall 3fu and bottom wall 3fb which extend in the horizontal direction and apart from each other and a pair of side walls 3fs and 3fs arranged between upper wall 3fu and bottom wall 3fb. These upper wall 3fu, bottom wall 3fb, and side walls 3fs and 3fs define internal space 3s 10 having a cross-sectional rectangular shape. Internal space 3s comprises a mutually facing pair of openings 3si and 3so. [0082] Heating chamber 3g having inlets 3gi, 3go is defined in internal space 3s provided in the downstream 15 side of the outlet of nozzle 3c. In this embodiment, the outlet of nozzle 3c is arranged at opening 3si of internal space 3s. Therefore, heating chamber 3g coincides with internal space 3s. In addition, inlet 3gi of heating chamber 3q coincides with opening 3si of 20 internal space 3s, and outlet 3go of heating chamber 3q coincides with opening 3so of internal space 3s. [0083] Nonwoven fabric F is conveyed by conveyor 2 so that it enters into heating chamber 3g through inlet 3gi, proceeds through heating chamber 3g, and then exits from 25 heating chamber 3g through outlet 3go. In this case, no roller or belt for conveying nonwoven fabric F is disposed within heating chamber 3g. In other words, nonwoven fabric F is conveyed within heating chamber 3g without being supported, Further, nonwoven fabric F is 30 conveyed within heating chamber 3g so that both surfaces Fs of nonwoven fabric F respectively continue to face upper wall 3fu and bottom wall 3fb that are the partition walls defining heating chamber 3g. [0084] On the other hand, the air flown out from 35 nozzle 3c enters into heating chamber 3g through inlet 3gi, proceeds through heating chamber 3g while contacting nonwoven fabric F being conveyed, and then exits from - 27 heating chamber 3g through outlet 3go. In this case, air is fed so that the linear velocity of the air is higher than the conveyance velocity of nonwoven fabric F. [0085] In this embodiment, upper wall 3fu and bottom 5 wall 3fb are, for example, formed from stainless steel sheets having a thickness of 3 mn. Length 13 of housing 3f or heating chamber 3g in the machine direction MD is 1675 mm. Width W3f of housing 3f is 240 mm, and width W3g of heating chamber 3g is 200 mm. Height H3f of housing 10 3f is 11 mm, and height H3g of heating chamber 3g is 5 mm. [0086] In this embodiment, upper wall 3fu and bottom wall 3fb extend in horizontal planes. Angle 0 formed between the orientation line of nozzle 3c and horizontal 15 plane H (see FIG. 4) is preferably 0 to 30 degrees, more preferably 0 to 10 degrees, and most preferably 0 degree. [0087] As shown in FIG. 3, bulkiness restoration system 1 further comprises cooler 4 for cooling nonwoven fabric F which is conveyed downstream from heater 3, with 20 a fluid. Cooler 4 comprises fluid source 4a, feed pipe 4b connected to the outlet of fluid source 4a, nozzle 4c connected to the outlet of feed pipe 4b, regulator 4d and cooling device 4e disposed in feed pipe 4b, and housing 4f. 25 [0088] In this embodiment, the fluid is air, and fluid source 4a is a compressor. If compressor 4a is operated, air flows through feed pipe 4b. The air pressure inside feed pipe 4b is reduced by regulator 4d. The air is then cooled by cooling device 4e. The cooled air then flows 30 out from nozzle 4c. [00891 Similarly to housing 3f of heater 3, housing 4f of cooler 4 comprises an upper wall and a bottom wall which extend apart from each other and a pair of side walls and arranged between the upper wall and bottom 35 wall, and these upper wall, bottom wall, and side walls define cooling chamber 4g having a cross-sectional rectangular shape. Cooling chamber 4g comprises inlet - 28 4gi and outlet 4go mutually facing with each other. [00903 Nonwoven fabric F is conveyed by conveyor 2 so that it enters into cooling chamber 4g through inlet 4 gi, proceeds through cooling chamber 4g, and then exits from 5 cooling chamber 4g through outlet 4go. In this case, no roller or belt f-or conveying nonwoven fabric F is disposed within cooling chamber 4g. In other words, nonwoven fabric F is conveyed within cooling chamber 4g without being supported. Further, nonwoven fabric F is 10 conveyed within cooling chamber 4g so that both surfaces Fs of nonwoven fabric F respectively continue to face upper wall and bottom wall that are the partition walls defining cooling chamber 4g. [0091] In this embodiment, nozzle 4c of cooler 4 is 15 arranged at inlet 4gi. Therefore, the air flown out from nozzle 4c enters into cooling chamber 4g through inlet 4gi and proceeds through cooling chamber 4g while contacting nonwoven fabric F being conveyed, and then exits from heating chamber 4g through outlet 4go. In 20 this case, air is fed so that the linear velocity of the air is higher than the conveyance velocity of nonwoven fabric F. [0092] Nonwoven fabric F unwound from roll R is conveyed so as to pass firstly through heating chamber 3g 25 of heater 3. Simultaneously, a heated air is fed from nozzle 3c of heater 3 into heating chamber 3g. Consequently, nonwoven fabric F is heated by contacting the heated air, and thereby the bulkiness of nonwoven fabric F is increased. That is, the bulkiness of 30 nonwoven fabric F is restored. [0093] In this case, air proceeds mainly along surfaces Fs of nonwoven fabric F. As a result, the restoration of bulkiness of the nonwoven fabric F is nor disturbed by the flow of air. That is, the bulkiness of 35 nonwoven fabric F is restored well. [0094] Furthermore, in this embodiment, in heating chamber 3g, the linear velocity of the air is higher than - 29 the conveyance velocity of nonwoven fabric F. As a result, turbulence is generated in the air flows adjacent to surfaces Ps of nonwoven fabric F. Therefore, various molecules contained in the air collide with surfaces Fs 5 of nonwoven fabric F at random angles. Accordingly, the fibers of nonwoven fabric F are loosen, and thereby promoting the restoration of bulkiness. In addition, due to the turbulence in the air flows, nonwoven fabric F flaps within heating chamber 3g. As a result, the heated 10 air easily enters into the inside of nonwoven fabric F and nonwoven fabric F can be efficiently heated. Therefore, length L3f of heating chamber 3g or housing 3f (FIG. 4) can be shortened. [0095] Furthermore, housing 3f does not require an 15 equipment for feeding air or an equipment for sucking out air. Therefore, housing 3f can be further reduced in size. [0096] Furthermore, in heating chamber 3g, nonwoven fabric F is conveyed without being supported by rollers, 20 etc. As a result, the restoration of bulkiness of nonwoven fabric F is not disturbed by the rollers, etc. [0097] Nonwoven fabric F conveyed out from heating chamber 3g is then conveyed so as to pass through cooling chamber 4g of cooler 4. Simultaneously, a cooled air is 25 fed from nozzle 4c of cooler 4 into cooling chamber 4g. Consequently, nonwoven fabric F contacts the cooled air and is cooled. [0098] Tn this case, air proceeds mainly along surfaces Fs of nonwoven fabric F. As a result, the 30 decrease in bulkiness ot nonwoven fabric F by the flow of: air is prevented. [0099] Further, the linear velocity of the air within cooling chamber 4g is higher than the conveyance velocity of nonwoven fabric F. As a result, it is possible to 35 cool the entire nonwoven fabric F located within cooling chamber 4g. That is, nonwoven fabric F can be efficiently cooled. Therefore, cooling chamber 4g and - 30 housing 4f can be reduced in size. [0100] Nonwoven fabric conveyed out from cooling chamber 4g is then conveyed by conveyor 2 to, for example, a system for producing an absorbent product. In 5 the system for producing an absorbent product, nonwoven fabric F is for example used as the top sheet of an absorbent product. [0101] In this embodiment, since nonwoven fabric comprises heat-fusible conjugate fibers, the temperature 10 of the air flown out from nozzle 3c of heater 3 is preferably equal to or more than the temperature which is lower than the melting point of the heat-fusible conjugate fibers (low-melting point component) by 50C and less than the melting point of the heat-fusible conjugate 15 fibers. If the temperature of air is lower than the melting point minus 50*C, the bulkiness of the nonwoven fabric may not be restored sufficiently. If the temperature of air is equal to or more than the melting point, the fibers will melt. 20 [0102] In view of efficient heating of nonwoven fabric F, heating chamber 3g is preferably small in cross sectional area, that is, small in width W3g and height 13g. However, during conveyance, nonwoven fabric F meanders in the width direction and flaps in the 25 thickness direction. Therefore, if width W3g or height H3g is excessively small, there is a possibility that nonwoven fabric F may collide with housing 3f. In addition, if the cross-sectional area of heating chamber 3g, i.e., the flow passage area for air, is excessively 30 small, the pressure loss at heating chamber 3g is larger. Considering these facts, width W3g is preferably larger than the width of nonwoven fabric F by 5 to 40 mm, and is more preferably larger than the width of nonwoven fabric F by 10 to 20 mm. Further, height 113g is preferably 2 to 35 10 mm, and more preferably 3 to 7 mm. [0103] In the embodiments described above, nozzle 3c of heater 3 was arranged at inlet 3gi of heating chamber - 31 3g. In another embodiment, nozzle 3c is arranged at outlet 3go of heating chamber 3g. In this case, air is fed so as to enter into heating chamber 3g through outlet 3go, to proceed through heating chamber 3g while 5 contacting nonwoven fabric F being conveyed, and then to exit from heating chamber 3g through inlet 3gi. [0104] Accordingly, air is fed so as to enter into heating chamber 3g through one of inlet 3gi and outlet 3go, to proceed through heating chamber 3g while 10 contacting nonwoven fabric F, and then to exit from heating chamber 3g through the other of inlet 3gi and outlet 3go. [0105] However, if nozzle 3c is arranged at outlet 3go, the machine direction MD of nonwoven fabric F and 15 the air flow are in opposite directions from each other. Therefore, it is necessary to increase the force in the machine direction MD which acts on nonwoven fabric F for conveyance, that is, the tension. If the tension is increased, there is a possibility that the restoration of 20 bulkiness of nonwoven fabric F may be prevented. A similar problem arises when nonwoven fabric F is allowed to meander in heating chamber 3g in the machine direction MD and in the direction opposite to the machine direction MD alternately. 25 [0106] In contrast, in an embodiment shown in FIGS. I to 3, nozzle 3c is arranged at inlet 3gi, and nonwoven fabric F is conveyed through heating chamber Sg so that the two surfaces Fs of nonwoven fabric F continue to face upper wall 3fu and bottom wall 3fb. Therefore, the 30 machine direction MD of nonwoven fabric F and the air flow are in the same direction with each other within heating chamber 3g. Therefore, the bulkiness restoration can be carried out while maintaining the tension applied to nonwoven fabric F for conveyance at a low level. 35 [0107] Further, in the embodiments described above, nozzle 3c is arranged above nonwoven fabric F at inlet 3gi. In another embodiment, nozzle 3c is arranged below - 32 nonwoven fabric F. Furthermore, in another embodiment, nozzles 3c are arranged both above and below nonwoven fabric F. [0108] FIGS. 6(A) and 6(B) show another embodiment of 5 nozzle 3c. Referring to FIG. 6(A), nozzle 3c comprises body 3ca having, for example, a rectangular shape. Body 3ca comprises internal space 3cb, air inlet 3cc and air outlet cd which are communicated with internal space 3cb, and air guide plate 3ce which extends adjacent to 10 air outlet 3cd. Air inlet 3cc is connected to feed pipe 3b. [0109] Nozzle 3c is integrally fastened to housing 3f. That is, as shown in FITG. 6(B), air guide plate 3ce of nozzle 3 is inserted into internal space 3s through 15 inlet 3si of internal space 3s of housing 3f, and body 3ca is fixed to upper wall 3fu of housing 3f. As a result, air passage Sa is formed between air guide plate 3ce and upper wall 3fu, and nonwoven fabric passage 5b is formed between air guide plate 3ce and bottom wall 3fb. 20 In this case, for example, height H5a of air passage 5a and thickness tce of air guide plate 3ce are respectively 1 rm, and height H5h of nonwoven fabric passage 5b is 3 mm. The width of nozzle 3c is substantially identical to the width of internal space 25 3s. [0110] Air passage 5a is communicated with air outlet 3cd of nozzle 3c and is also communicated with internal space 3s of housing Sf. In this case, heating chamber 3g is defined downstream of the outlet of air passage 5a. 30 Therefore, the heated air which is fed from feed pipe 3b to body 3ca flows through air outlet 3d into air passage 5a, flows through air passage 7a, and then flows through inlet 3gi into heating chamber 3g. [0111] Nonwoven fabric passage 5b is on the one hand 35 communicated With the outside of housing 3f, while on the other hand is communicated with heating chamber 3g. Nonwoven fabric F enters into nonwoven fabric passage 5b - 33 from outside of housing 3f, proceeds through nonwoven fabric passage 5b, and then enters into heating chamber 3g through inlet 3gi. [0112] In this case, the flow passage area at outlet 5 3go of heating chamber 3g is larger than the flow passage area of nonwoven fabric passage 5b, and accordingly the flow passage resistance at outlet 3go is smaller than that of nonwoven fabric passage 5b. Therefore, the air which flown into heating chamber 3g through inlet 3gi is 10 prevented from flowing backward through nonwoven fabric passage 5b, and thereby can flow steadily toward the outlet 3go through heating chamber 3g. [0113] In the embodiment shown in FTG. 7, bottom wall 3fb of housing 3f is extended to below body 3ca of nozzle 15 3c, as compared with the embodiment which is shown in FIG. 6. As a result, nonwoven fabric passage 5b is also extended to below body 3ca of nozzle 3c. [0114] The arrangement of nozzle 4c of cooler 4 is similar to the arrangement of nozzle 3c of heater 3. 20 [0115] Furthermore, in the embodiments described above, cooler 4 is disposed downstream of heater 3. In another embodiment, cooler 4 is omitted. That is, nonwoven fabric F unloaded from heater 3 is conveyed to the production system without being cooled by cooler 4. 25 [0116] In still another embodiment, a heater for heating housing 3f is disposed. The temperature of the inside surface of housing 3f defining heating chamber 3g is maintained by this heater at, for example, substantially the same temperature as the temperature of 30 the air flown out from nozzle Sc. In such an embodiment, restoration of bulkiness of the nonwoven fabric F can be promoted. A silicone rubber heater manufactured by Threehigh Co., Ltd., can be used as the heater for housing 3f. In still another embodiment, a heater for 35 heating nozzle 3c is disposed. [0117] In still another embodiment, a heat insulating material for covering housing 3f'L is disposed. The - 34 temperature decrease inside housing 3f or heating chamber 3g is suppressed by the heat insulating material. In sti1 another embodiment, a heat insulating material for covering nozzle 3c is disposed. 5 [0118] Various embodiments described above may be combined with each other. Examples [0119] The present invention will now be explained in more detail on the basis of examples and comparative 10 examples, and the present invention is not limited by the examples and comparative examples. The measurement methods of the properties evaluated in examples and comparative examples are as follows. [Basis Weight] I5 The basis weight was measured according to JIS L 1906, 5.2. [0120] [Bulkiness] The bulkiness was measured using a thickness gauge 20 (THICKNESS GAUGE U- F-60 manufactured by Daiei Kagaku Seiki Mfg. Co., Ltd.) while applying a load of 3.0 gf/cm- to a nonwoven fabric. Ten different points of the nonwoven fabric were measured for bulkiness (thickness) , and an average value of the ten measurement values was 25 determined as the bulkiness (thickness) of the nonwoven fabric. [0121] [Compression Properties] The compression properties were evaluated using an automated compression testLer KES-FB3 manufactured by Kato 30 Tech Corp. The measurement conditions were as follows. SENS: 2 Speed: 0.02 mm/sec. Stroke: 5 mm/10 V 35 Compression area: 2 cm 2 Capture interval: 0.1 sec. Upper load limit: 50 g/cm 2 - 35 Repetition number: 1 [0122] The compression properties were evaluated based on the compressional energy per 1 cm 2 of nonwoven fabric, WC (N-m/m2) and the compressional resilience RC (%) 5 Measurements were carried out total three times, and the average values of WC and RC are calculated. A higher WC value means that it is more easily to be compressed, and an RC value closer to 100% means higher recovery properties. 10 [0123] [Liquid Permeability] The liquid permeability was evaluated using a LISTER strike-through tester manufactured by LENZING AG. The evaluation procedure is as follows. (1) A sample cut out to a size of 100 x 100 mm is 15 placed on 5 sheets of a filter paper (ADVANTEC FILTER PAPER GRADE 2) cut out to a size of 100 x 100 mm, and an electrical liquid permeation plate was placed thereon. (2) The filter paper, sample and electrical liquid permeation plate were set on the strike-through tester. 20 (3) A 5 mL of physiological saline was poured into the body of the strike-through tester. (4) The physiological saline (at room temperature) was allowed to drop frm the body of the strike-through tester through an opening of the elect-rical liquid 25 permeation plate. (5) The electrification time of the electrical liquid permeation plate was recorded. (6) The measurement was carried out three times, and an average value of the liquid permeation time is 30 calculated out. The liquid permeation time was 69.13 seconds when no sample was set, i .e., with only 5 sheets of the filter paper. [0124] [Examples 1 to 2 and Comparative Examples 1 to 35 31 (1) Bulkiness Restoration Treatment A nonwoven fabric in the form of roll was provided.

- 36 This nonwoven fabric is an air-through nonwoven fabric having a texture on the air-through treated surface (the surface to which hot air has been applied) . The properties of the nonwoven fabric are shown in Table I. 5 In Table 1, WF, tm, and tO respectively represent the width of the nonwoven fabric, the thickness of the nonwoven Fabric before it is wound around roll R, and the thickness before it is conveyed into the bulkiness restoration system. The thickness of the nonwoven fabric 10 was measured using a thickness gauge FS-60 DS manufacture by Daiei Kagaku Seiki Manufacturing Co., Ltd. The surface area of the pressing plates was 20 cm2 (circle), and the measurement load was 0.3 kPa (3 gf /cm [0125] [Table 11 -___ _ -------- -- C--- ---- ard. method Web forming method Card method Fiber bonding method - Air through method (heat using) Fiber structure - Core-sheath structure Material of core -Polyethylene terephthalate Material of sheath P2*olyethylene Multilayer structure Double layer structure of fiber Top Fiber length mm 3 8 layer Denier dtex 1.3 Basis weight g/m 2 7 Bottom Fiber length nUM 45 ------------------ _ layer Denier dtex 2.2 [B:a 9Basis weight g/m 2 17 ---------- Total basis weight g7/m2 23.18 WF m 0.16 Tm mm 34 15 The bulkiness restoration system according to the embodiment shown in FIGS. 3 to 5 was used to carry out a bulkiness restoration treatment for the nonwoven fabric. Y747-304SS manufactured by Spraying Systems was used as 20 nozzle 3c. PFD-802-40 manufactured by CKD was used as flowmeter 3ba. AR30-03 manufactured by SMC Corporation was used as regulator 3d. Microcable Air Heater (Model Type: MCA-3P-5000, 200V, 5 kW) manufactured by Sakaguchi E.-I. Voc Corporation was used as electric heater 3e.

- 37 [0126] The treatment conditions in Examples 1 and 2 are shown in Table 2. In Table 2, THAi represents the temperature of the air at the inlet of: the heating chamber, qHA represents the air flow (O*C) discharged from 5 the compressor, SHA (= W3g -13g) represents the air flow passage area in the heating chamber, VHA (= qHA/SHA) represents the linear velocity of air in the heating chamber, VF represents the conveyance velocity of the nonwoven fabric, and TH (=L3g/VF) represents the heating 10 time of the nonwoven fabric, that is, the time during which the nonwoven fabric is retained in the heating chamber. [0127] [Table 2] Units- Example 1 Exampie 2 THAi C 85 116 qHA m 3 /min. (0") 7. 13 4. 75 L2g m 6.70 3.35 W3g m 0.20 0.20 H3g m 0.005 0.005 2 SHA m 0.001 0.001 VHA m/mn. 1783 2377 VF r/m.in 400 200 trH sec. 1.005 1.005 15 [0128] Bulkiness Restoration Treatment in Comparative Examples 1 to 3 The same nonwoven fabric as that of- Examples I and 2 was provided. The bulkiness restoration system shown in FIG. 8 was used to carry out a bulkiness restoration 20 treatment for the nonwoven fabric. Referring '-o FIG. 8, the bulkiness restoration system for Comparative Examples 1 to 3 was comprised of air permeable belt 22 driven by a pair of rollers 21, 21, and the nonwoven fabric FF unwound from a roll was conveyed on belt 22 in the 25 machine direction MD. The bulkiness restoration system was further comprised of hot air feeder 31 for feeding hot air, suction device 32 for sucking the air from hot air feeder 31, cold air f-eeder 41. for feeding a cold air, and suction device 42 for sucking the air from cold air - 38 feeder 41. Hot air Feeder 31 was comprised of a fan. Hot air feeder 31 and suction device 32 were arranged facing with each other across space S3, and cold air feeder 41 and suction device 42 were arranged facing with 5 each other across space S4. Belt 22 passed through these spaces S3 and S4, and therefore nonwoven fabric FF was conveyed through spaces S3 and S4. At the same time, hot air was red trom hot air feeder 31 perpendicular to a surface of the nonwoven fabric FF. The hot air passed 10 through nonwoven fabric FF, and then was sucked by suction device 32. In the same manner, a cold air was fed from cold air feeder 41 perpendicular to a surface or nonwoven fabric FE. The cold air passed through nonwoven fabric FF, and then was sucked by suction device 42. 15 [0129] The treatment conditions in Comparative Examples 1 to 3 are shown in Table 3. In Table 3, THAi' represents the temperature of the air flown out from hot air feeder 31, qHA' represents the air flow (804C) discharged from hot- air feeder 31, Ps' represents the 20 static pressure (80"C) at hot air feeder 31, L3g' and W3g' represent the machine direction length and width of the parts where air flow is generated, in hot air feeder 31 and suction device 32, SHA' (-L3g' -W3g') represents the air flow passage area in space S3, VHA' (= qHA'/SHA') 25 represents the linear velocity of air in space S3, SF' (= L3g' -WF) represents the surface area of the nonwoven fabric part located within space S3, that is, the nonwoven fabric part through which air passes, VF' represents the conveyance velocity of the nonwoven 30 fabric, and TH' represents the heating time, that is, the time during which the nonwoven fabric is retained in space 33.

- 39 [0130] [Table 3] Units Comarative Comparative Comparative ] E xample 1. Example 2 Example3 THAi' C 80 10' 0 120 qHA r /min. 20.4 20..4 O2. L3g' r 3.4 3-_4 3.4 W3g' m 0.2 0.2 0.2 SHA' mz 0.68 0.68 0.68 VHA' m/min. 30 30 30 SF' m 0.544 0.544 0.544 yF m/min 40 40 40 (3) The properties oD-F bulky Nonwoven Fabrics that have been subjected to bulkiness restoration treatment 5 The properties of the bulky nonwoven fabrics that have been subjected to the bulkiness restoration treatment under the conditions of Examples 1 and 2 and Comparative Examples I to 3 are shown in Table 4. TO and Tm represent the thicknesses of a nonwoven fabric under a 10 constant pressure (0.5 gf/cm2 for TO, and 50 gf/cm 2 for Tm) during the compression test. The higher the TO value, the better the fluffy feeling. in addition, the higher the Tm value, the better the thickness retention during compression. For example, when the nonwoven 15 fabric is used as a top sheet of an absorbent article (for example, diaper) , the nonwoven fabric is hard to crush even if a pressure (for example, a pressure generated when the wearer sit down, etc. ) is applied to the absorbent article.

40 [Table 4] Before Examples Comparative bulkiness Examp les restoration 1 2 2 3 (before conveyance to ___________________ System)_______j______ Basis weight 23.18 23.77 24.03 24.34 24.28 24.53 Pu kiness 0.45 0.60 1.15 0.59 1. 11 1.26 (mm) Specific 19.41 2524 47. 86 24 23 45.72 52.18 volume (Cm 3 /g) WC (N-m/m 2 ) 0.37 0.69 1.56 3 65 .41 1.77 RC (%) 60.49 62.28 55.00 59.41 52.33 48 1!6 TO (mm) 0.61 0 9 i 1.57 8 5 .38 1.57 Tm (mm) 0.18 0 19 0.37 0.18 0.27 0.38 Permeation 21.41 12.30 2.38 13.69 2.35 1.52 time (sec.) [0131] (4) Electron Microscope Observation on Heat fused Parts 5 The heat-fused parts of the heat-fusible conjugate fibers in the nonwoven fabrics before bulkiness restoration (before conveyance to the bulkiness restoration system) and in the bulky nonwoven fabrics obtained by bulkiness restoration treatment under the 10 conditions of Examples 1 and 2 and Comparative Examples 1 to 3 were observed by Real Surface View Microscope VE 7800 manufactured by KEYENCE Corporation. At this time, the accelerating voltage was set to 2 kv, the magnification was set to 30 to 1500 times, and the stage 15 height was set to 10 mm. Each bulky nonwoven fabric was cut out into a predetermined size with a sharp razor, and was fixed to an observation stage with a double-sided tape. [0132] First, the textured surface of each nonwoven 20 fabric was observed under a magnification of 300 times, about 5 heat-fused parts could be observed for the nonwoven fabric before bulkiness restoration, and about 10 heat-fused parts could be observed for the bulky nonwoven fabrics after bulkiness restoration treatment, 25 and therefore each heat-fused part was magnified by 1500 - 41 times to observe the form of the heat-fused parts. [0133] The electron microscope photographs of the heat-fused parts under a magnification of 1500 times are shown in FIGS. 9 to 14. 5 FIGS. 9(a) to (c) are electron microscope photographs of a nonwoven fabric before bulkiness restoration (before conveyance to the bulkiness restoration system), FIGS. 10(a) to (c) are electron microscope photographs of a nonwoven fabric subjected to 10 bulkiness restoration treatment under the conditions of Example 1, FIGS. 11(a) to (c) are electron microscope photographs of a nonwoven fabric subjected to bulkiness restoration treatment under the conditions of Example 2, FIGS. 12(a) to (c) are electron microscope photographs of 15 a nonwoven fabric subjected to bulkiness restoration treatment under the conditions of Comparative Example 1, FIGS. 13(a) to (c) are electron microscope photographs of a nonwoven fabric subjected to bulkiness restoration treatment under the conditions of Comparative Example 2, 20 and FIGS. 14(a) to (c) are electron microscope photographs of a nonwoven fabric subjected to bulkiness restoration treatment under the conditions of Comparative Example 13. [0134] As shown in FIG. 9, in the nonwoven fabric 25 before bulkiness restoration, heat-fu sible conj2ugate fibers are bitina into each other at the heat-fused parts, and the distance between the heat-fusible conjugate fibers F3 is smaller than the sum of the fiber radii of each heat-fusible conjugate fiber. A sample for 30 observing a cross-section cut to a direction (CD direction) perpendicular to the conveyance direction (MD direction) during the manufacture of a nonwoven fabric was prepared, and was observed for the heat-fused parts in -the vicinity of the texture surface, the middle part 35 of the texture surface and a flat surface, and in the vicinity of a flat surface to find out that heat-fusibie conjugate fibers are biting into each other at almost - 42 every parts. [01351 As shown in FIGS. 12 to 14, in the nonwoven fabrics that have been subjected to the bulkiness restoration treatment under the conditions of Co0mparative 5 Examples 1 to 3, the heat-fusible conjugate fibers are biting into each other as in the nonwoven fabric before bulkiness restoration. In addition, a tendency of increasing in the surface area of the heat-fused parts in the surface direction of the heat-fusible conjugate 10 fibers was observed with the increase in temperature of the hot air (800C in Comparative Example 1, 1004C in Comparative Example 2, and 120'C in Comparative Example (0136] As shown in FIGS. 10 and 11, heat-fused bulge 15 arts as shown in FIG. 1 were observed in the nonwoven fabrics that have been subjected to bulkiness restoration treatment under the conditions of Examples 1 and 2. The heat-fusible conjugate fibers are slightly spaced away from each other at the heat-fused bulge parts, and the 20 distance between the heat- fusible conjugate fibers is larger than the sum of the fiber radii of each heat fusible conjugate fiber. In addition, a part where cracks have been generated was observed. Moreover, the constriction of the heat--fused parts became remarkable 25 with the increase in temperature during the bulkiness restoration treatment. [0137] It is considered that the difference in for of heat-fused parts as shown in FIGS. 9 to 14 is due to the presence or absence of the bulkiness restoration 30 treatment and the type of the bulkiness restoration treatment. [0138] That is, in the air-through method used in Comparative Examples I to 3, heat is less likely to be transferred to the movable conveyor on which a nonwoven 35 fabric before bulkiness restoration is disposed, the hot air is required to have a high temperature to achieve a sufficient bulkiness restoration. In addition, although - 43 the velocity of the hot air may be relatively low, when hot air passes through the conveyor surface on which the nonwoven fabric is disposed, a force which compresses the nonwoven fabric before bulkiness restoration is applied 5 in the direction perpendicular to the conveyor surface. Therefore, in Comparative Examples 1 to 3, it is considered that the surfaces of: the heat--fusible conjugate fibers easily melt by a high-temperature hot air, and the molten, heat-fusible conjugate fibers are 10 compressed with each other by the action of the high temperature hot air, and thereby the heat-fusible conjugate fibers are biting with each other. [0139] In contrast, in Examples 1 and 2, hot air flows in parallel to the nonwoven fabric before bulkiness 15 restoration, and the velocity of the hot air is higher than the velocity of the nonwoven fabric, and therefore a turbulent flow is generated w'ihin the bulkiness restoration system, thereby promoting heat transfer. In addition, since a force is not applied to the constituent 20 fibers of nonwoven fabric F in the same direction but is applied to the constituent fibers along the flow of air, the heat-fused bulge parts slightly extend and chance into heat-fused constriction parts. [0140] (5) Observation 25 As shown in Table 4, the bulky nonwoven fabrics obtained by the bulkiness restoration treatment under the conditions of Examples 1 and 2 have a basis weight which is substanJally the same as that of the nonwoven fabric before bulkiness restoration, but have a bulkiness, a 30 specific volume, a WC value and a RC value larger than those of the nonwoven fabric before bulkiness restoration. At the same basis weight, the greater the bulkiness, the higher the void volume (specific volume), and the higher the WC value, the greater the compression 35 deformation properties, and an RC value closer to 100% indicates higher compression recovery properties. Therefore, the bulky nonwoven fabrics obtained by -44 bulkiness restoration treatment under the conditions of Examples 1 and 2 have a high void volume (specific volume) and have excellent compression deformation properties and compression recovery properties, as 5 compared with the nonwoven fabric before bulkiness restoration. [0141] In addition, the bulky nonwoven fabrics obtained by the bulkiness restoration treatment under the conditions of Examples 1 and 2 have a basis weight which 10 is substantially the same as that of the nonwoven fabrics obtained under the conditions of Comparative Examples 1 to 3, but have a bulkiness, a specific volume, a WC value and a RC value that are similar to or greater than those of the nonwoven fabrics obtained under the conditions of 15 Comparative Examples I to 3. In particular, comparing Example I and Comparative Example 1 in which the hot air temperature is similar to each other (85"C for Example and 804C for Comparative Example 1), Example I exhibited a WC value representing compression deformation properties 20 and a RC value representing compression recovery properties higher than those of Comparative Example 1. In the nonwoven fabric subjected to bulkiness restoration treatment under conditions of Example 1, heat-fused bulge parts were changed into heat-fused constriction parts, 25 and the joining strength between heat-fusible conjugate fibers through a heat-fused part has been decreased due to the change in shape of the heat-fused parts from a bulge from to a constriction form. Therefore, it is considered that the nonwoven fabric 30 subjected to the bulkiness rest-oration under the conditions of Example 1 has a degree of freedom to compression deformation higher than that- of the nonwoven fabric subjected to the bulkiness restoration treatment under the conditions of Comparative example 1, and 35 thereby ma king it easier for the fibers to move. Accordingly, it is considered that nonwoven fabric subjected to the bulkiness restoration treatment under - 45 the conditions of Example I has a WC value representing compression deformation properties higher than that of the nonwoven fabric subjected to the bulkiness restoration treatment under the conditions of Comparative 5 Example 1. [0142] In addition, it is considered that, in the nonwoven fabric subjected to bulkiness -restoration treatment under the conditions of Example 1, heat easily transfers to the heat-fusible conjugate fibers during 10 bulkiness restoration treatment, and therefore the resins which constitute the heat-fusible conjugate fibers are oriented by the heat, and thereby the crystallinity is improved. Therefore, it is considered that, in the nonwoven fabric subjcted to the bulkiness restoration 15 treatment under the conditions of Example 1, the initial strength of' fibers is improved, and accordingly the fibers are Less likely to deform by initial deformation, and thereby the shape retention properties are improved, as compared -to Comparative Example 1. Therefore, it is 20 considered that the nonwoven fabric subjected to the bulkiness restoration treatment under the conditions of Example 1 has a RC value representing compression restoration properties higher than that of the nonwoven fabric subjected to bulkiness restoration treatment under 25 the conditions of Comparative Example 1. Explanation of Symbols (0143] Fl to F4 Heat-fusible conjugate fibers R1, R2 Intersection regions of heat-fusible conjugate 30 fibers B1 Heat-fused constriction part B2 Heat-fused bulge part P1, P2 Center of -the intersection region of heat-fused conjugate fibers 35 Z1, Z2 Overlapping direction of heat-fusible conjugate fibers Al, A2 Center line (a virtual line extending in - 46 overlapping direction of the heat-fusible conjugate fibers through the center of intersection region of the heat-fusible conjugate fibers) rl r2 Fiber radii of heat-fusible conjugate fibers 5 r3 Distance between heat-fusible conjugate fibers

Claims

1. A nonwoven fabric comprising heat-fusible conjugate fibers intersecting and overlapping with each other and heat-fused constriction parts at the 5 intersection regions of the heat-fusible conjugate fibers, wherein when a virtual line extending in the overlapping direction of the heat-fusible conjugate fibers through the center of an intersection region is 10 defined as a center line, the heat-fused constriction parts have a surface which is recessed toward the center line, wherein the distance between the heat fusible conjugate fibers that are heat-fused through a 15 heat-fused constriction part is larger than the sum of the fiber radius of each heat-fusible conjugate fiber, wherein the nonwoven fabric has a thickness of 0.5 to 3.0 mm under a load of 3.0 of/cm 2 and a specific volume of 6 to 300 cm 3 /g. 20 2.. The nonwoven fabric according to claim 1, wherein the nonwoven fabric has a plurality of heat-fused parts at the intersection regions of the heat-fusible conjugate fibers intersecting and overlapping with each other, and 25 wherein the proportion of the number of the heat-fused constriction parts to the total number of the heat-fused parts included in a predetermined region of the nonwoven fabric is 1/10 to 9/10.

3. The nonwoven fabric according to claim 1 or 2, 30 wherein the heat-fusible conjugate fibers have a fiber diameter of 10 to 30 pm .

4. The nonwoven fabric according to any one of claims I to 3, wherein the heat-fusible conjugate fibers comprise a first component. and a second component having 35 a melting point lower than that of the first component, and wherein the weight ratio of the second component to the first component (the second component/the first - 48 component) is 4/6 to 8/2.

5. The nonwoven fabric according to any one of claims 1 to 4, wherein the nonwoven fabric is obtained by a bulkiness restoration treatment of a nonwoven fabric 5 before bulkiness restoration, comprising heat-fused, heat-*-fusible conjugate fibers, wherein the bulkiness restoration treatment comprises: a step of providing a heating chamber having an inlet and an outlet, and 10 a step of, while conveying the nonwoven fabric before bulkiness restoration so as to enter into tne heating chamber through the inlet, to proceed through the heating chamber, and then to exit from the heating chamber through the outlet, feeding a heated fluid at a 15 velocity higher than the conveyance velocity of the nonwoven fabric before bulkiness restoration so as to enter into the heating chamber through one of the inlet and outlet, to proceed through the heating chamber while contacting the nonwoven fabric, and then to exit from the 20 heating chamber through the other of the inlet and outlet.

6. The nonwoven fabric according to claim 5, wherein the nonwoven fabric before bulkiness restoration is an air-through nonwoven fabric obtained by air-through treatment of a web comprising heat-fusible conjugate fibers to heat-fuse the heat-fusible conjugate fibers.

7. The nonwoven fabric according to claim 5 or 6, wherein the heated fluid enters into the heating chamber through the inlet and exits from the heating chamber 30 through the outlet.

8. The nonwoven fabric according to any one of claims 5 to 7, wherein the nonwoven fabric before bulkiness restoration is conveyed through the heating chamber without being supported. 35 9. The nonwoven fabric according to any one of claims 5 to 8, wherein the heating chamber is defined by two walls that extend from the inlet to the outlet and - 49 are separated from each other, and wherein the nonwoven fabric before bulkiness restoration is conveyed within Lhe heating chamber so that both surfaces of the nonwoven fabric before bulkiness restoration respectively continue 5 to face the walls.