JP2008144322A - Nonwoven fabric, method for producing the same, and absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonwoven fabric so designed that fiber high-density regions and fiber low-density regions are formed so as to disperse in a planar direction and the liquid migration from a surface sheet to a liquid-absorbing form is not hindered, and the diffusivity of a liquid is low when the liquid permeates through the absorbing form, and to provide a method for producing the nonwoven fabric, and to provide an absorbent article using the same. <P>SOLUTION: The nonwoven fabric 5 has a plurality of high-density regions 11 mainly composed of heat-shrunk heat-shrinkable fibers and a plurality of low-density regions 12 mainly composed of mutually thermofused thermofusible fibers, wherein the plurality of high-density regions 11 and the plurality of low-density regions 12 are formed so as to disperse in the planar direction in the nonwoven fabric 5, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a nonwoven fabric, a method for producing a nonwoven fabric, and an absorbent article.

  Conventionally, for example, for the purpose of improving liquid drawability and liquid transferability (spot property) in a nonwoven fabric used for absorbent articles, various devices have been made regarding the types of fibers to be blended in the nonwoven fabric and the structure of the nonwoven fabric. Here, the good liquid drawing-in property means that the liquid transfer from the top sheet to the absorber is not disturbed, and the high liquid spot property means that the diffusibility when the liquid permeates is low.

For example, in an absorbent article in which a liquid-permeable sheet made of a fiber material is disposed between a liquid-permeable surface sheet and a liquid-holding absorber, this liquid-permeable sheet is the most absorbent material. It consists of a multilayer structure having a first layer located on the near side and a second layer located on the side closest to the topsheet, and the first layer has a higher fiber density than the second layer. Thus, an absorbent article is proposed in which the capillary force increases from the second layer toward the first layer (see, for example, Patent Document 1).
JP 2004-33236 A

  However, even in the liquid-permeable sheet described in Patent Document 1, the liquid transfer from the top sheet to the absorber is not hindered, but the liquid transfer from the top sheet to the absorber is not hindered. It is difficult to say that the low diffusivity when the liquid permeates is compatible. Further, in the first layer located on the side closest to the absorber, the fiber density is entirely high, and when a large amount of liquid is discharged to the top sheet, the liquid is preferably transferred to the absorber. Can be difficult.

  In view of the above, the present invention is formed so that the high-density region and the low-density region of the fiber are dispersed in the plane direction, and does not prevent the liquid from transferring from the topsheet to the absorber, and the diffusibility when the liquid permeates. An object of the present invention is to provide a non-woven fabric having a low thickness, a method for producing the non-woven fabric, and an absorbent article using the non-woven fabric.

  The present inventors heated a fiber web containing heat-fusible fibers and heat-shrinkable fibers under predetermined conditions so that the high-density regions and low-density regions of the fibers are dispersed in the plane direction. The present inventors have found that a non-woven fabric that is formed and has low diffusibility when the liquid permeates and does not hinder the transfer of the liquid from the topsheet to the absorbent body can be produced.

  (1) A non-woven fabric having a substantially uniform thickness including a heat-fusible fiber and a heat-shrinkable fiber and a heat-shrinkable fiber that is crimped at least in a heat-shrinked state, A high-density region composed of the heat-shrinkable fibers shrunk and having a fiber density higher than the average fiber density in the nonwoven fabric, and a fiber density composed mainly of the heat-fusible fibers fused to each other and lower than the average fiber density Each of the plurality of low-density regions and the plurality of high-density regions and the plurality of low-density regions are formed so as to be dispersed in a plane direction perpendicular to the thickness direction of the nonwoven fabric. A non-woven fabric formed so that all or part of the low-density region communicates from one side to the other side in the thickness direction.

  (2) The nonwoven fabric according to (1), wherein the heat-shrinkable fiber exhibits heat-shrinkability at a temperature higher than a temperature at which the heat-fusible fiber can be melted.

  (3) The non-woven fabric according to (1) or (2), wherein the heat-shrinkable fibers in the high-density region are crimped in a screwed manner and thermally contracted so as to involve the heat-fusible fibers.

  (4) The nonwoven fabric according to any one of (1) to (3), wherein each of the plurality of low density regions is formed around each of the composite high density regions.

  (5) In a state where the shrinkage of the nonwoven fabric is suppressed by fusing the heat-fusible fiber to a fiber that contacts the heat-fusible fiber to form a network structure, the heat-shrinkable fiber is heated. The nonwoven fabric according to any one of (1) to (4), wherein the plurality of high-density regions and the plurality of low-density regions are formed by shrinking.

  (6) The nonwoven fabric according to any one of (1) to (5), wherein a dispersion index indicating a degree of dispersion in the plurality of high-density regions and the plurality of low-density regions is 250 to 790.

  (7) A non-woven fabric having a substantially uniform thickness including a heat-fusible fiber and a heat-shrinkable fiber and a heat-shrinkable fiber having at least a heat-shrinkable state. Made of the heat-shrinkable fibers and having a fiber density higher than the average fiber density in the nonwoven fabric, and mainly made of the heat-fusible fibers fused to each other at a fiber density lower than the average fiber density. A plurality of low density regions, and the plurality of high density regions and the plurality of low density regions are formed so as to be dispersed in a plane direction perpendicular to the thickness direction of the nonwoven fabric. All or part of the density region is a non-woven fabric manufacturing method formed so as to communicate from one side to the other side in the thickness direction, which is a heat-fusible fiber and a heat-shrinkable fiber, Heat shrink A transport step of transporting a fiber web containing heat-shrinkable fibers having crimpability in a state to a predetermined heating device, and heat of the heat-shrinkable fibers by the heating device while transporting the fiber web in a predetermined direction. A shrink heating step in which heat treatment is performed at a temperature at which yield can be expressed, and by adjusting the transport speed of the fiber web in the transport step and / or the transport speed of the fiber web in the shrink heating step, A non-woven fabric manufacturing method for adjusting the mode of the high density region and the low density region.

  (8) The transport speed of the fiber web in the shrink heating step is a ratio of the transport speed of the fiber web in the shrink heating step to the transport speed of the fiber web in the transport step is the heating temperature in the shrink heating step. (7) The nonwoven fabric manufacturing method as described in (7) adjusted so that it may become larger than the heat shrink ratio of the said fiber web.

  (9) It is a step prior to the shrink heating step, in order to regulate the degree of freedom of the heat shrinkable fiber by reducing the thickness of the fiber web, and the heat fusible fiber is substantially And a preheating step in which the heat-shrinkable fibers are heat-treated at a temperature at which the heat-shrinkable fibers are not substantially thermally shrunk, and the method for producing a nonwoven fabric according to (7) or (8).

  (10) A fusion heating step that is a step prior to the shrink heating step, the heat fusible fiber is meltable, and the heat shrinkable fiber is heated at a temperature at which the heat shrinkable fiber does not substantially shrink. The nonwoven fabric manufacturing method in any one of (7) to (9) containing this.

  (11) In the fusion heating step, the heat-fusible fiber is melted and fused to a fiber that is in contact with the fusible fiber to form a network structure. The nonwoven fabric manufacturing method according to (10), wherein the heat-shrinkable fibers are thermally contracted in a state where the shrinkage of the fibrous web is suppressed to form the plurality of high-density regions and the plurality of low-density regions.

  (12) In the shrink heating step, any of (7) to (11) is suppressed by inhibiting the shrinkage of the heat-shrinkable fibers contained in the fiber web by reducing friction applied to the fiber web. The nonwoven fabric manufacturing method as described in any one of.

  (13) In the shrink heating step, the fibrous web includes a breathable first support member and a breathable second support that is disposed substantially parallel to the upper side in the vertical direction at a predetermined distance from the first support member. It is conveyed in a state of being disposed between the members, and hot air having a predetermined temperature is blown from the lower side in the vertical direction of the first support member, and hot air having a predetermined temperature is blown from the upper side in the vertical direction of the second support member. By this, The nonwoven fabric manufacturing method as described in (12) which heat-processes this fiber web in the state spaced apart from the said 1st support member and / or the said 2nd support member in all or one part in the said fiber web.

  (14) The nonwoven fabric production method according to (13), wherein the fiber web is heat-treated in a relaxed state.

  (15) At least a liquid-permeable top sheet, a liquid-impermeable back sheet, a liquid-retaining absorber disposed between the top sheet and the back sheet, and the top sheet One or a plurality of second sheets disposed between the absorbent body and the one or more second sheets, each of which is a heat-fusible fiber and a heat-shrinkable fiber. A heat-shrinkable fiber having a crimpability in at least a heat-shrinked state, and having a substantially uniform thickness, comprising mainly the heat-shrinkable fiber that has been heat-shrinked, and an average fiber density in the non-woven fabric. A non-woven fabric having a plurality of high-density regions each having a high fiber density and a plurality of low-density regions mainly composed of the heat-fusible fibers fused to each other and having a fiber density lower than the average fiber density. The nonwoven fabric Each of the plurality of high-density regions and the plurality of low-density regions in the nonwoven fabric is formed so as to be dispersed in a plane direction perpendicular to the thickness direction in the nonwoven fabric, and all or part of the plurality of low-density regions. Is an absorbent article formed so as to communicate from one side to the other side in the thickness direction.

  (16) In the second sheet, the average fiber density in the second sheet is higher than the average fiber density in the top sheet, and the fiber density in the high-density region is lower than the average fiber density in the absorber (15). Absorbent article as described in 1.

  (17) The absorbent article according to (15) or (16), including two second sheets, wherein the two second sheets have different contents in the high-density region and the low-density region.

  According to the present invention, the nonwoven fabric is formed so that the high-density region and the low-density region of the fiber are dispersed in the plane direction, and does not disturb the liquid transfer from the top sheet to the absorbent body and has low diffusibility when the liquid permeates. The manufacturing method of this nonwoven fabric and the absorbent article using this nonwoven fabric can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view of an absorbent article according to the present invention. FIG. 2 is an XX cross-sectional view of the absorbent article of FIG. FIG. 3 is a view showing the nonwoven fabric in the cross-sectional view of FIG. FIG. 4 is a cross-sectional view of the nonwoven fabric in the present invention. FIG. 5 is an enlarged cross-sectional view of the nonwoven fabric in the present invention. FIG. 6 is a plan view and a perspective view of the nonwoven fabric in the present invention. FIG. 7 is a diagram for explaining a non-woven fabric density structure in the present invention. FIG. 8 is a diagram illustrating the liquid absorption behavior when the nonwoven fabric according to the present invention is used as a second sheet of an absorbent article. FIG. 9 is a diagram illustrating the first manufacturing method. FIG. 10 is a diagram for explaining the second manufacturing method. FIG. 11 is Table 1 explaining the measurement conditions of the nonwoven fabric production conditions and the average absorbance in the examples. FIG. 12 is Table 2 illustrating the evaluation results of the absorbability of the nonwoven fabric in the examples.

[1] Nonwoven Fabric An embodiment of the nonwoven fabric of the present invention will be described with reference to FIGS.

[1.1] Overall Configuration As shown in FIGS. 3 to 7, the nonwoven fabric 5 is a heat-fusible fiber 120 and a heat-shrinkable fiber that is a heat-shrinkable fiber and has a crimpability in at least a heat-shrinked state. A non-woven fabric having a substantially uniform thickness including the fibers 110, the high-density region 11 mainly composed of heat-shrinkable fibers 110 that are heat-shrinked, and having a fiber density higher than the average fiber density in the non-woven fabric 5; And a plurality of low density regions 12 each having a fiber density lower than the average fiber density.

  As shown in FIG. 5, each of the plurality of high density regions 11 and the plurality of low density regions 12 is formed so as to be dispersed in the planar direction of the nonwoven fabric 5. As shown in FIG. 3 or FIG. 4, all or some of the plurality of low density regions 12 are formed so as to communicate from one side to the other side in the thickness direction of the nonwoven fabric 5.

  In the nonwoven fabric 5 in this embodiment, for example, the heat-fusible fiber 120 is in a state in which the shrinkage of the nonwoven fabric 5 is suppressed by fusing the fibers in contact with the heat-fusible fiber 120 to form a network structure. The heat-shrinkable fiber 110 is a nonwoven fabric in which the high-density region 11 and the low-density region 12 are formed by heat-shrinking.

[1.2] Heat-sealable fiber and heat-shrinkable fiber The nonwoven fabric 5 is a heat-sealable fiber 120 and a heat-shrinkable fiber 110 that is crimpable in at least a heat-shrinkable state. And a non-woven fabric having a substantially uniform thickness. Specifically, it is a nonwoven fabric obtained by heat-treating a fiber web in which heat-fusible fibers 120 and heat-shrinkable fibers 110 are mixed under predetermined conditions.

  The heat-shrinkable fiber 110 can be exemplified by an eccentric core-sheath type composite fiber or a side-by-side type composite fiber containing two types of thermoplastic polymer materials having different shrinkage rates as components. Examples of thermoplastic polymer materials having different shrinkage rates include a combination of ethylene-propylene random copolymer and polypropylene, a combination of polyethylene and ethylene-propylene random copolymer, a combination of polyethylene and polyethylene terephthalate, and the like. Specific examples include trade name EP manufactured by Chisso, MSW manufactured by Toyobo, and CPP manufactured by Daiwabo. For example, heat-shrinkable fibers having latent crimpability are preferred.

  Further, the heat-shrinkable fiber 110 is, for example, a staple fiber having a short length of 5 to 90 mm and a thickness of about 1 to 11 Dtex.

  Examples of the heat-fusible fiber 120 include fibers made of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). Moreover, the fiber comprised from an ethylene-polypropylene copolymer, polyester, polyamide, etc. can also be used. A core-sheath type composite fiber or a side-by-side composite fiber made of a combination of these thermoplastic polymer materials can also be used.

  The heat-fusible fiber 120 is, for example, a staple fiber having a short fiber length of 5 to 90 mm and a thickness of about 1 to 11 Dtex.

  The mixing ratio of the heat-shrinkable fiber 110 and the heat-fusible fiber 120 is preferably 10% by mass to 90% by mass, more preferably 30% by mass to 70% by mass with respect to the total fiber amount. The mass% is more preferable. When the content of the heat-shrinkable fiber 110 is in the above range, the heat-fusible fiber 120 is intertwined with the heat-shrinkable fiber 110 by multiplying the shrinkage action of the heat-shrinkable fiber 110 or the fiber-bonded heat-fusible fiber 120. The high density region 11 and the low density region 12 can be suitably formed.

  The heat-fusible fiber 120 is preferably 90% by mass or less, more preferably 70% by mass or less, based on the total amount of fibers in the nonwoven fabric 5. When the content rate of the heat-fusible fiber 120 is within the above range, the network structure can be suitably formed because the bonding points between the heat-fusible fibers 120 can be sufficiently provided. Moreover, since the joining point of the heat-fusible fibers 120 can be sufficiently maintained, sufficient tensile strength can be maintained in the manufacturing process of the nonwoven fabric 5 and the process added to manufacture the absorbent article and the like.

The heat shrink rate of the heat-shrinkable fiber 110 is 10% or more, preferably 20 to 80% at a predetermined temperature (for example, 145 ° C. (418.15 K)). As a method for measuring the heat shrinkage rate, for example, (1) a 200 g / m ² web is prepared with the fiber to be measured (100%), (2) cut into a size of 250 × 250 mm, and (3) adjusted to a predetermined temperature. The heat shrinkage rate can be calculated by leaving it in the oven for 5 minutes, (4) measuring the length dimension after shrinkage, and (5) calculating the length dimension difference before and after heat shrinkage.

  For example, the heat-fusible fiber 120 does not exhibit heat shrinkability or exhibits heat shrinkability, but has a heat shrinkage rate of 10% or less at the predetermined temperature (for example, 145 ° C. (418.15 K)), preferably Is less than 7% fiber. When the heat shrinkage rate in the heat-shrinkable fiber 110 and the heat-fusible fiber 120 is as described above, the high-density region 11 and the low-density region 12 can be suitably formed. That is, the nonwoven fabric formed so that the high-density region 11 and the low-density region 12 are dispersed in the plane direction due to the difference in the heat shrinkage rate by heating the fiber web mixed with fibers having different heat shrinkage rates at a predetermined temperature. Obtainable.

  Further, the heat-shrinkable fiber 110 exhibits heat-shrinkability at a temperature higher than the temperature at which the heat-fusible fiber 120 can be melted. It is preferable that the heat-shrinkable fiber 110 exhibits heat-shrinkability at a temperature that is 5 ° C. or more higher than the temperature at which the heat-fusible fiber 120 melts, preferably 10 ° C. or more. In this case, for example, the network structure can be formed by performing heat treatment at a temperature at which the heat-fusible fiber 120 is melted and the heat-shrinkable fiber 110 does not exhibit the heat-shrinkability.

  Furthermore, since the temperature at which the heat-shrinkable fiber 110 melts is higher than the heat-shrinkable temperature of the heat-shrinkable fiber 110, the heat-shrinkable fiber 110 that exhibits the heat-shrinkability that constitutes the high-density region 11 is obtained. The heat-fusible fiber 120 is fused at the intersection with the heat-fusible fiber 120, but the heat-shrinkable fibers 110 are included in a substantially unfused state. That is, the heat-shrinkable fiber 110 entrains other fibers by heat-treating the fiber web in which the network structure is formed at a temperature at which the heat-shrinkable fiber 110 exhibits the heat-shrinkability and does not melt. Thus, the high density region 11 and the low density region 12 can be formed.

[1.3] High Density Region and Low Density Region The high density region 11 is a region having a fiber density higher than the average fiber density in the nonwoven fabric 5 mainly composed of heat-shrinkable fibers 110 that have undergone heat shrinkage. For example, as shown in FIG. 5, the high-density region 11 is a region in which the heat-shrinkable fibers 110 are crimped in a screwed manner and heat-shrinked (crimped) so that fibers such as the heat-fusible fibers 120 are involved. It is.

  The high-density region 11 includes, for example, a fiber such as the heat-fusible fiber 120 that is entangled with the heat-shrinkable fiber 110 by the heat shrinkage of the heat-shrinkable fiber 110 or is disposed around the heat-shrinkable fiber 110. It is formed by moving in the contraction direction of 110 (for example, to collect). Accordingly, the heat-shrinkable fiber 110 is heat-shrinked or the network structure formed by joining the heat-fusible fibers 120 and the high-density region 11 in which the heat-fusible fibers 120 are moved while shrinking. The low density region 12, which is a region that could not be moved even by the shrinkage of the heat-shrinkable fiber 110, is formed so as to be dispersed in the plane direction.

  As shown in FIG. 4, the low density region 12 is a region having a fiber density lower than the average fiber density of the nonwoven fabric 5 mainly composed of heat-fusible fibers 120 fused to each other. As shown in FIG. 3 or FIG. 4, for example, the low density region 12 is formed so as to communicate from one side to the other side in the thickness direction of the nonwoven fabric 5. By forming the low density region 12 so as to communicate from one side to the other side in the thickness direction of the nonwoven fabric 5, the liquid present on one side of the nonwoven fabric 5 can be suitably transferred to the other side. is there.

  Moreover, as shown in FIG. 4 or FIG. 6, the low density region 12 is formed in a dispersed manner in the plane direction of the nonwoven fabric 5 and is formed around the high density region 11. By forming the low density region 12 around the high density region 11, the liquid drawn by the high density region 11 is transferred to the low density region 12, and the predetermined direction in the thickness direction of the nonwoven fabric 5 by the low density region 12. Can be suitably transferred. For example, when the nonwoven fabric 5 is used as the second sheet, the liquid left inside the low density region 12 is transferred to the high density region 11 when the liquid present on the top sheet side in the nonwoven fabric 5 is transferred to the absorber side. be able to.

  Here, the inter-fiber distance in the high-density region 11 is, for example, 10 to 30 μm. The interfiber distance in the low density region 12 is, for example, 100 to 300 μm.

  For example, the high-density region 11 and the low-density region 12 are formed by forming the network structure by fusing the heat-fusible fiber 120 to the fiber in contact with the heat-fusible fiber 120 to form the fiber web (nonwoven fabric 5). The high-density region 11 and the low-density region 12 can be formed by thermally shrinking the heat-shrinkable fiber 110 in a state where the shrinkage is suppressed. The other forming method is as described in the nonwoven fabric manufacturing method described later.

[1.4] Dispersion index (standard deviation of mean absorbance)
The high density region 11 and the low density region 12 are formed by being dispersed in the plane direction of the nonwoven fabric 5. The degree of dispersion in the planar direction can be represented by, for example, a dispersion index (standard deviation of average absorbance). The dispersion index in the nonwoven fabric 5 of this embodiment is, for example, 250 to 790, preferably 310 to 705.

  When the dispersion index is smaller than 250, the high-density region 11 and the low-density region 12 are too close to a uniform state, so that the diffusibility when liquid passes through the low-density region 12 is low, and the high-density region 11 may not be compatible with liquid absorbency such as not disturbing the liquid transfer from the top sheet to the absorber. When the dispersion index is larger than 790, the high density region 11 and the low density region 12 are too unevenly distributed, so that the liquid temporarily captured in the low density region 12 cannot be transferred to the high density region 11. When the low diffusibility when the liquid permeates in the low density region 12 and the liquid absorbency such as not disturbing the liquid transfer from the top sheet to the absorber in the high density region 11 cannot be achieved. There is. For this reason, the dispersion index in the nonwoven fabric 5 of this embodiment is, for example, 250 to 790, preferably 310 to 705.

  The standard deviation of the average absorbance, which is a dispersion index, can be measured and calculated by using a predetermined measuring instrument (for example, a formation tester (product number: FMT-MIII, manufactured by Nomura Corporation)). For example, the camera correction sensitivity is 100%, the binarization threshold ±%: 0.0, the moving pixel is 1, the effective size is 25 × 18 cm, and the surface supported by the support member in the manufacturing process is the front side. Can be measured. The dispersion index can also be measured by other known measurement methods.

  Here, the higher the dispersion index, the greater the formation unevenness. That is, it can be said that the high density region 11 and the low density region 12 are dispersed in the plane direction. Further, it can be said that the difference in absorbance between the high density region 11 and the low density region 12 is large. That is, it can be said that the difference in fiber density between the high density region 11 and the low density region 12 is large.

[1.5] Others The nonwoven fabric 5 in the present embodiment is an example in which the high-density region 11 and the low-density region 12 are dispersed in the plane direction, and the high-density region 11 and the low-density region 12 communicate with each other in the thickness direction. . The effect when this nonwoven fabric 5 is used as a second sheet of an absorbent article is as follows. FIG. 7 can be used for understanding the following description.
(1) Since the low-density area | region 12 is connecting, the liquid excreted by the surface sheet in large quantities can be rapidly taken in a second sheet, without diffusing in a surface sheet (spot property).
(2) Since the high-density region 11 communicates and the density is higher than that of the top sheet, the liquid excreted in the top sheet can be suitably transferred to the absorbent body disposed on the other side of the nonwoven fabric 5. In addition, it is possible to further suppress the liquid remaining on the surface side and inside the surface sheet (liquid drawing property).
(3) Since the fibers in the low density region 12 are connected to the fibers in the adjacent high density region 11, the fibers remain in the low density region or in the surface sheet positioned on the upper surface of the low density region. The liquid that has been discharged can also be transferred to the high density region.

  For example, the absorption behavior of the liquid 900 will be described with reference to FIGS. 8A to 8D. As shown in FIG. 9A, the liquid 900 such as menstrual blood excreted in the top sheet 20 in the absorbent article 1A is retained in the recesses (grooves) in the top sheet 20, thereby suppressing diffusion in the surface direction. However, it is transferred to the absorber 40 through the second sheet 50. As the second sheet 50 in the absorbent article 1A, the nonwoven fabric 5 in the present embodiment is used.

  As shown in FIG. 8 (B), the non-woven fabric 5 that is the second sheet 50 has low diffusibility when the liquid permeates, and therefore, for example, the liquid 900 accumulated in the recess (groove) is preferably used on the absorber 40 side. Transition.

  And as shown in FIG.8 (C), since the nonwoven fabric 5 which is a 2nd sheet | seat does not prevent the transfer of the liquid from a surface sheet to an absorber, it is contained in the convex part (peak part) in the surface sheet 20, for example. The liquid can be drawn and transferred to the absorber 40.

  Further, as shown in FIG. 8D, since the liquid 900 is suitably transferred to the absorber 40, the top sheet 20 and the second sheet 50 can be dried to a predetermined state. Even if the liquid 900 such as blood is excreted repeatedly, it is possible to repeat the above liquid transfer and liquid drawing. As a result, the surface layer of the surface sheet may be excellent in dryness.

  That is, the absorbent article 1A in FIGS. 8A to 8D uses the surface sheet 20 having an uneven surface (mountain groove shape), but this allows the liquid 900 to be stored in the recessed portion (groove portion). Therefore, the diffusion of the liquid 900 on the surface side can be suppressed. Then, the liquid 900 stored in the concave portion (groove portion) is suitably transferred to the absorbent body 40 by the nonwoven fabric 5 that is the second sheet 50. Also from this point, the liquid diffusibility in the surface sheet 20 can be suppressed. Furthermore, since the nonwoven fabric 5 which is the second sheet 50 has low diffusibility when the liquid permeates, the liquid 900 inside the top sheet is drawn into the second sheet 50 and transferred to the absorber 40. Thereby, the quick-drying property in the surface sheet 20 is improved. Furthermore, since the top sheet 20 and the second sheet 50 can be dried to a predetermined state by suitably transferring the liquid 900 to the absorber 40, the liquid 900 such as menstrual blood is repeatedly excreted on the top sheet 20. However, it is possible to repeat the above liquid transfer and liquid drawing. Moreover, it is possible to maintain the absorptivity as 1 A of absorbent articles. An absorbent article 1A shown in FIGS. 8A to 8D is one of the preferred embodiments of the absorbent article using the nonwoven fabric 5 in the present embodiment.

[2] Manufacturing Method of Nonwoven Fabric A manufacturing method of the nonwoven fabric 5 will be described mainly with reference to FIG. 9 or FIG. As shown in FIG.

Conveying step of conveying the fiber web 500 including the heat-fusible fiber 120 and the heat-shrinkable fiber 110 which is the heat-shrinkable fiber 110 and has at least a heat-shrinkable state to the second heating device 520. And a shrink heating process in which the second heating device 520 heats the fiber web 500 in a predetermined direction at a temperature at which the heat shrinkability of the heat shrinkable fiber can be exhibited. And the aspect of the high density area | region 11 and the low density area | region 12 can be adjusted by adjusting the conveyance speed of the fiber web 500 in a conveyance process, and / or the conveyance speed of the fiber web 500 in a shrink heating process.

  Here, in the manufacturing method of the nonwoven fabric 5, the heating process for forming the density (high density area and low density area) includes a first manufacturing method including a plurality of heating processes including the shrink heating process, and the density (high density area). The second manufacturing method in which the heating process for forming the low density region) is only the shrink heating process will be described below.

[2.1] First Manufacturing Method A first manufacturing method for the nonwoven fabric 5 will be described with reference to FIGS. 9 and 10. A 1st manufacturing method is a manufacturing method which consists of a several heating process including a shrinkage heating process as a heating process for forming sparse / dense (a high density area | region and a low density area | region). Specifically, a heat fusion process in which the heat-fusible fibers 120 included in the fiber web 500 are fused together to form a network structure, and heat shrinkage in a state where the network structure is formed and overall shrinkage is suppressed. A shrinkage heating step for causing heat shrinkage in the conductive fiber 110. As a 1st manufacturing method, for example, as heating for forming the density (high density field and low density field) in nonwoven fabric 5, a manufacturing method including a heating process in two stages of a fusion heating process and a shrink heating process Can be illustrated. Below, the specific content of a 1st manufacturing method is demonstrated.

[2.1.1] Opening Step and First Conveying Step As shown in FIG. 9, the nonwoven fabric manufacturing apparatus 590 uses the card device 501 to heat-shrink fibers 110 and heat-fusible fibers 120 in the opening process. The fiber web 500 having a predetermined thickness is continuously formed by opening the raw material mixed with the above. In the step of blending the heat-shrinkable fibers 110 and the heat-fusible fibers 120, a fiber web 500 that is an aggregate having a degree of freedom between the fibers is formed.

  Examples of the fiber web 500 include a fiber web formed by a card method and a fiber web formed by an airlaid method. And in order to form in a nonwoven fabric obtained so that a high density area | region and a low density area | region may disperse | distribute suitably, the web formed by the card | curd method which uses a comparatively long fiber is preferable, for example.

  The fiber web 500 is conveyed at a speed S1 to the entrance of the first heating device 510 by the conveyors 503 and 505 in the first conveying step. In this 1st conveyance process, the fiber web 500 is conveyed in the state which maintained the freedom degree of the fibers of a fiber web.

[2.1.2] Fusing and Heating Step In the fusing and heating step, the fiber web 500 is subjected to fusing and heating treatment while being conveyed at the conveying speed S2 by the conveyor 515 inside the first heating device 510. Specifically, heat treatment is performed by blowing hot air at a predetermined temperature from the upper surface side of the fiber web 500 in a state of being conveyed by the conveyor 515. The heating temperature in the first heating device 510 is a temperature at which the heat-fusible fiber 120 melts and is a temperature at which the heat-shrinkable fiber 110 does not substantially shrink. The heat-fusible fibers 120 included in the fiber web 500 are fused together to form a network structure. That is, in the fusion heating step, the fusion is mainly performed so that the heat-fusible fibers 120 in the fiber web are temporarily bonded to each other.

  As shown in FIG. 9, in the first heating device 510, the fiber web 500 is heated with hot air that heats the fiber web 500 to a temperature at which the heat-fusible fiber 120 can be melted and the heat-shrinkable fiber 110 does not substantially heat shrink. It sprays from the upper side of 500 toward the lower side. Since the fiber web 500 is heated while being pressed against the support member 511 by the hot air blown from the upper side, the fiber web 500 is heated by fusion while the friction between the fiber web 500 and the support member 511 is high. While the shrinkage of the fiber web 500 is inhibited, the heat-fusible fibers 120 are fused to form a network structure.

[2.1.3] Second Conveying Step and Shrinkage Heating Step As shown in FIG. 9, in the second conveying step, the conveyor 525 is moved by the second heating device 520 arranged continuously to the first heating device 510. Then, the fiber web 500 subjected to the fusion heat treatment in the fusion heating step is conveyed at a conveyance speed S3.

  In the shrink heating process, the second heating device 520 develops the heat shrinkability of the heat shrinkable fibers 110 included in the fiber web 500 while the fiber web 500 conveyed by the conveyor 515 is conveyed in a predetermined direction by the conveyor 525. Shrink heat treatment at possible temperature. That is, in the state where the network structure is formed and the shrinkage of the fiber web 500 itself is suppressed, the heat treatment is performed so that the heat shrinkage in the heat shrinkable fiber 110 is expressed.

  As described above, the heat-shrinkable fibers 110 are thermally contracted in a state where the network structure is formed and the shrinkage of the fiber web 500 is suppressed, so that a high-density region and a low-density region can be formed. For example, due to the shrinkage of the heat-shrinkable fibers 110, the heat-shrinkable fibers 120 are entangled or moved in the periphery in the fiber web 500 in the shrinking direction. In addition, a low density region can be formed. In other words, since the network structure is formed by joining the heat-shrinkable fibers 110 together with the high-density region accumulated by the shrinkage of the heat-shrinkable fibers 110, the fibers cannot be moved due to the shrinkage of the heat-shrinkable fibers 110. It is possible to mix the low density area which is the same area.

  The heat treatment in the shrink heating process is performed at a temperature higher than the heat treatment temperature in the fusion heating process. This is because the heat shrink temperature at which the heat shrinkability of the heat shrinkable fibers 110 is higher than the melting temperature of the heat fusible fibers 120 to be fused in the fusion heating step. For example, the shrink heating temperature in the shrink heating step is heat-treated at a temperature higher by 5 ° C. or more, preferably 10 ° C. or higher than the fusion heating temperature in the fusion heating step.

  Furthermore, the heat treatment in the second heating device 520 in the shrink heating process is performed in a state in which the friction between the fiber web 500 and the lower support member 525 is small in order to suppress shrinkage inhibition of the fiber web 500 itself. Is preferred.

  For example, as shown in FIG. 9, the fiber web 500 in the second heating device 520 includes a lower side support member 521 that is a breathable first support member and a vertical upper side at a predetermined distance from the lower side support member 521. And the upper support member 523 which is a breathable second support member disposed substantially in parallel with the upper support member 523. Then, hot air of a predetermined temperature is blown from the lower side of the lower support member 521 in the vertical direction, and hot air of a predetermined temperature is blown from the upper side of the upper side support member 523 in the vertical direction, so that all or part of the fiber web 500 Can be heat-treated in a state of being separated from the lower support member 521 and / or the upper support member 523.

  In this case, the hot air is blown onto the fiber web 500 from both the upper and lower sides of the fiber web 500, but the hot air is alternately blown up and down in the conveying direction of the fiber web 500 to support the fiber web 500 as a whole on the lower side. Heat treatment can be performed in a state of being separated from the member 521 and the upper support member 523. Thereby, the friction between the fiber web 500, the lower support member 521, and the upper support member 523 is reduced, so that the heat treatment can be performed in a state where the inhibition of shrinkage of the fiber web 500 is suppressed.

  The temperature of the hot air in this case is, for example, 100 to 160 ° C. (373.15 to 433.15 K), preferably 120 to 140 ° C. (393.15 to 413.15 K). The hot air from the upper direction is, for example, 4 to 13 m / s, preferably 7 to 10 m / s, and the hot air from the lower direction is, for example, 4 to 13 m / s, preferably 7 to 10 m / s. is there.

  In addition, the heat treatment in the second heating device 520 in the shrink heating process is preferably performed in a state where the fiber web 500 is slackened in order to suppress shrinkage inhibition of the fiber web 500 itself.

  For example, as shown in FIG. 10, the front conveyor 525a and the rear conveyor 525b are separated from each other by a predetermined distance in the second heating device 520 and continuously arranged in the transport direction. The support member or the like is not disposed between the front conveyor 525a and the rear conveyor 525b, and hot air is blown from the lower side of the fiber web 500, so that the friction applied to the fiber web 500 is substantially reduced. No region can be formed. Further, by performing heat treatment in a state where the fiber web 500 disposed in this region is slackened, inhibition of shrinkage of the fiber web 500 itself (particularly, inhibition of shrinkage in the transport direction) can be further suppressed. In order to form this slackness, for example, the slackness can be formed by making the transport speed S5 of the rear conveyor 525b slower than the transport speed S4 of the front conveyor 525a.

  Specifically, as shown in FIG. 10, the fiber web 500 is blown by hot air from above while being supported and transported by the front lower support member 521a disposed on the front conveyor 525a, and then in a separated region. Hot air is blown from below and supported by the upper support member 523 or separated from the rear conveyor 525b, and further hot air is blown from above to be supported by the lower lower support member 521b. Are transported. By doing in this way, the shrinkage | contraction inhibition in the fiber web 500 can be suppressed suitably, and the high density area | region and low density area | region in the nonwoven fabric 5 can be formed suitably.

  The ratio of the conveyance speed S3 of the fiber web 500 in the shrink heating process to the conveyance speed S2 of the fiber web 500 in the conveyance process is the heat of the fiber web 500 at the heat treatment temperature in the shrink heating process for the fiber web 500 conveyed in the conveyance process. It can be adjusted to be larger than the shrinkage ratio. That is, the thermal contraction in the shrink heating process of the fiber web 500 that has been heat-treated in the fusion heating process to form the network structure is performed in a regulated state. Here, the conveyance speeds S <b> 2 and S <b> 3 can be set with reference to, for example, the heat shrink ratio at the heating temperature in the shrink heating process of the heat shrinkable fiber 110. Here, the heat shrinkage ratio refers to the length after heat shrinkage with respect to the length of heat shrinkage in a free state.

[2.2] Second Manufacturing Method The second manufacturing method is a manufacturing method in which the heating step for forming the high-density region and the low-density region in the nonwoven fabric 5 is only the shrink heating step. For example, in the nonwoven fabric manufacturing apparatus 590 of FIG. 9, a manufacturing method in which heat treatment is performed at a temperature at which the heat shrinkability of the heat shrinkable fiber 110 is expressed by the second heating apparatus 520 without performing the heat treatment by the first heating apparatus 510. It can be illustrated.

  And in this manufacturing method, as for the conveyance speed S3 of the fiber web 500 in a shrink heating process, ratio of this conveyance speed S3 with respect to the conveyance speed S2 of the fiber web 500 in a conveyance process is the fiber web 500 in the heating temperature in a shrink heating process. It is adjusted to be larger than the heat shrinkage ratio. That is, the thermal contraction in the contraction heating process in the fiber web 500 in which the heat-shrinkable fiber 110 and the heat-fusible fiber 120 are mixed is performed in a regulated state. Here, the conveyance speeds S2 and S3 can be set, for example, with reference to the heat shrinkage ratio at the heating temperature in the shrinkage heating process of the heat shrinkable fiber 110 and the heat fusible fiber 120.

[2.3] Others As a method of manufacturing the nonwoven fabric 5, for example, a process prior to the shrink heating process, and heating for regulating the degree of freedom of the heat shrinkable fibers 110 by reducing the thickness of the fiber web 500. Steps may be included. Specifically, it may include a preheating step in which heat treatment is performed at a temperature at which the heat-fusible fiber 120 is not substantially melted and the heat-shrinkable fiber 110 is not substantially heat-shrinkable. In the 1st manufacturing method, it is included as a process before a fusion heating process.

[3] Absorbent article The absorbent article 1 in the present embodiment is an absorbent article including the above-described nonwoven fabric as a constituent. For example, as shown in FIG. 1 or FIG. 2, the absorbent article 1 includes the nonwoven fabric 5 as a second sheet.

  The absorbent article 1 in the present embodiment is a liquid retaining property that is disposed between the top sheet 2 and the back sheet 3, at least a part of which is a liquid permeable top sheet 2, a liquid-impermeable back sheet 3. The absorbent body 4 and the nonwoven fabric 5 that is one or a plurality of second sheets disposed between the top sheet 2 and the absorbent body 4.

  As shown in FIG. 4 or 5, each of the nonwoven fabrics 5 that are one or a plurality of second sheets includes heat-fusible fibers 120 and heat-shrinkable fibers that are crimped in at least heat-shrinked state. A non-woven fabric having a substantially uniform thickness including the shrinkable fibers 110. Each of the nonwoven fabrics 5 is mainly composed of heat-shrinkable fibers 110 that are thermally contracted, and a high-density region 11 that has a fiber density higher than the average fiber density in the nonwoven fabric 5 and heat-sealable fibers that are primarily fused together. 120 and a plurality of low density regions 12 each having a fiber density lower than the average fiber density. Each of the plurality of high density regions 11 and the plurality of low density regions 12 is formed so as to be dispersed in the plane direction of the nonwoven fabric 5. Furthermore, all or some of the plurality of low density regions 12 are formed so as to communicate from one side to the other side in the thickness direction of the nonwoven fabric 5. Here, the structure and manufacturing method of the nonwoven fabric 5 are as described above.

  The absorbent article 1 in the present embodiment has a low diffusibility when the liquid permeates, and uses the non-woven fabric 5 that does not prevent the liquid from being transferred from the top sheet to the absorber as the second sheet. It is an absorbent article that does not hinder the transfer of liquid to the body. Here, the absorption behavior of the liquid 900 shown in FIGS. 8A to 8D is as described above.

  The nonwoven fabric 5 used as the second sheet for the absorbent article 1 has an average fiber density in the nonwoven fabric 5 higher than the average fiber density of the surface sheet, and a fiber density in the high-density region 11 lower than the average fiber density in the absorbent body 4. Is preferred.

  Moreover, what laminated | stacked the two nonwoven fabrics 5 can be used as a 2nd sheet | seat. For example, what laminated | stacked the two nonwoven fabrics 5 from which each content rate of the low density area | region 12 and the high density area | region 11 differs can be used as a second sheet. In this case, for example, a second sheet having a non-uniformity (fiber density) gradient of the low density region 12 can be obtained.

  When the surface with a high content of the low density region 12 in the second sheet is disposed on the top sheet side, the liquid in the top sheet 2 can be quickly transferred to the absorber 4 side.

  Moreover, when the surface with a high content rate of the low density area | region 12 is arrange | positioned at the absorber 4 side, the liquid contained in the surface sheet 2 can be drawn in suitably and can be made to transfer to the absorber 4 side. Further, since the heat-shrinkable fibers 110 crimped in a screwed manner shown in FIG. 5 are formed on the surface in contact with the top sheet 2, the friction between the top sheet 2 and the second sheet is increased, and adhesion for joining is performed. The amount of agent used can be reduced. Further, the heat-shrinkable fibers 110 crimped in a threaded manner are entangled with the fibers of the surface sheet 2, so that even if a twist occurs in the absorbent article 1, the surface sheet 2 and the second sheet are not easily displaced.

    That is, the absorbent article 1A in FIGS. 8A to 8D uses the surface sheet 20 having an uneven surface (mountain groove shape), but this allows the liquid 900 to be stored in the recessed portion (groove portion). Therefore, the diffusion of the liquid 900 on the surface side can be suppressed. Then, the liquid 900 stored in the concave portion (groove portion) is suitably transferred to the absorbent body 40 by the nonwoven fabric 5 that is the second sheet 50. Also from this point, the liquid diffusibility in the surface sheet 20 can be suppressed. Furthermore, since the nonwoven fabric 5 which is the second sheet 50 has low diffusibility when the liquid permeates, the liquid 900 inside the top sheet is drawn into the second sheet 50 and transferred to the absorber 40. Thereby, the quick-drying property in the surface sheet 20 is improved. Furthermore, since the top sheet 20 and the second sheet 50 can be dried to a predetermined state by suitably transferring the liquid 900 to the absorber 40, the liquid 900 such as menstrual blood is repeatedly excreted on the top sheet 20. However, it is possible to repeat the above liquid transfer and liquid drawing. Moreover, it is possible to maintain the absorptivity as 1 A of absorbent articles. An absorbent article 1A shown in FIGS. 8A to 8D is one of the preferred embodiments of the absorbent article using the nonwoven fabric 5 in the present embodiment. Furthermore, when the opening part is formed in the recessed part (groove part) at a predetermined interval, the liquid 900 excreted in the top sheet 2 can be more suitably transferred to the second sheet and the absorber 4. Therefore, this is one of the preferred embodiments.

  Examples of absorbent articles include sanitary napkins, diapers, panty liners, incontinence pads, interlabial pads, breast milk pads, and the like.

  In addition, in this embodiment, although the nonwoven fabric 5 is used as a second sheet, it is not limited to this, For example, you may use the nonwoven fabric 5 as a surface sheet.

[4] Others [4.1] Each component The other components are described in detail below. The liquid permeable region constituting all or part of the surface sheet 2 is formed of a resin film having a large number of liquid permeable holes, a net sheet having a large number of meshes, a liquid permeable nonwoven fabric, or a woven fabric. Is done. As the resin film and the net-like sheet, those formed of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET) or the like can be used. Moreover, as a nonwoven fabric, the spunlace nonwoven fabric formed from cellulose fibers, such as rayon, a synthetic resin fiber, the air through nonwoven fabric formed from the said synthetic resin fiber, etc. can be used. Moreover, as a raw material, natural products capable of biodegradability such as polylactic acid, chitosan, polyalginic acid and the like can be used. In addition, a large number of liquid-permeable holes may be formed, and a silicone-based or fluorine-based water-repellent oil agent may be applied to make it difficult for body fluids to adhere to the outer surface.

Also, the basis weight is preferably 100 g / ^{m 2} to 15, more preferably 50 g / ^{m 2} to 20, particularly preferably 40 g / ^{m 2} to 25. If the basis weight is 15 g / m ² or less, sufficient surface strength cannot be obtained, and there is a risk of breaking during use. Moreover, in the case of 100 g / m < ² > or more, excessive wrinkle will develop and a discomfort will be produced during use. Furthermore, in the case of long-time use, if it exceeds 40 g / m ² , the liquid is held by the top sheet 2 and is kept in a sticky state, which makes it uncomfortable. Further, the density is not particularly limited as long as it is 0.12 g / cm ³ or less and liquid permeable. When the density is higher than this, it is difficult to smoothly transmit between the fibers of the surface sheet. In the case of menstrual blood, those having a low density are preferred because they are more viscous than urine and the like.

  When the liquid permeable region constituting all or part of the topsheet 2 is an apertured film such as a film in which a large number of liquid permeable apertures are formed as described above, the aperture diameter is from 0.05 mm. It is preferable that the pitch is in the range of 3 mm, the pitch is in the range of 0.2 mm to 10 mm, and the aperture area ratio is in the range of 3% to 30%.

  In addition, a plurality of holes can be formed integrally with the second sheet in the liquid permeable region constituting all or part of the top sheet 2. The arrangement of the apertures is not particularly limited, such as a staggered pattern, a lattice pattern, or a wavy pattern. Examples of the shape of the opening include a round shape, an elliptical shape, and a square shape. Further, a valve may be provided on the periphery of the opening.

  The back sheet 3 is made of a material that can prevent excrement absorbed by the absorber 4 from leaking outside. In addition, by using a moisture-permeable material, it is possible to reduce stuffiness at the time of wearing, and to reduce discomfort at the time of wearing. Such materials include, for example, a liquid-impermeable film mainly composed of polyethylene (PE), polypropylene (PP), etc., a breathable film, a composite in which a liquid-impermeable film is laminated on one side of a nonwoven fabric such as spunbond. A sheet etc. are mentioned. Preferably, a hydrophobic nonwoven fabric, a water-impermeable plastic film, a laminate sheet of a nonwoven fabric and a water-impermeable plastic film, or the like can be used. Alternatively, an SMS nonwoven fabric in which a melt-blown nonwoven fabric having high water resistance is sandwiched between strong spunbond nonwoven fabrics may be used.

The absorber 4 is comprised by the cushion arrange | positioned at the surface sheet 2 side, and an absorber material, for example. The absorbent material has a function of absorbing and holding a liquid such as menstrual blood, and is preferably bulky, hardly deformed, and has little chemical irritation. For example, the absorber material which consists of a fluffy pulp or an airlaid nonwoven fabric and a superabsorbent polymer can be illustrated. In place of the fluffy pulp, for example, artificial cellulose fibers such as chemical pulp, cellulose fiber, rayon, and acetate can be exemplified. Pulp is 500 g / m ² , polymer is 20 g / m ² (the polymer is dispersed throughout), and a mixture of pulp and polymer uniformly distributed is wrapped in a tissue with a weight of 15 g / m ² Can be mentioned. As an airlaid nonwoven fabric, for example, a nonwoven fabric in which pulp and synthetic fibers are thermally fused or fixed with a binder can be exemplified. Examples of the superabsorbent polymer (SAP) include starch-based, acrylic acid-based, and amino acid-based particulate or fibrous polymers.

  Although the shape and structure of the absorber 4 can be changed as necessary, the total absorption amount of the absorber 4 needs to correspond to the design insertion amount as the absorbent article and the desired application. Moreover, the size, absorption capacity, etc. of the absorber 4 are changed according to the application.

[4.2] Evaluation method of absorbability In order to evaluate the absorbability of a sample, the liquid persistence, diffusibility and rewetting can be evaluated by artificial menstrual blood. Here, the composition of artificial menstrual blood is as follows.
The following is blended with 1 liter of ion-exchanged water.
(1) Glycerin 80g
(2) Carboxymethylcellulose sodium (NaCMC) 8g
(3) Sodium chloride (NaCl) 10g
(4) Sodium bicarbonate (NaHCO 3) 4 g
(5) Dye Red No. 102 ... 8g
(6) Dye Red No. 2 ... 2g
(7) Dye Yellow No. 5 ... 2g

  As a measuring instrument, for example, 1) Auto Bullet (Metrohm, Inc. Model 725), 2) SKICON, 3) Colorimeter, 4) Perforated acrylic plate (40 mm × 10 mm hole in the center, length × width = 200 mm) × 100 mm, weight 130 g), 5) scale, 6) ruler, 7) artificial menstrual blood, 8) stopwatch, 9) filter paper.

  An evaluation sample is prepared as follows. The surface sheet is cut into length × width = 100 mm × 60 mm (arbitrary), and the basis weight and thickness are measured. Subsequently, the nonwoven fabric which is a measurement sample is cut into length × width = 100 mm × 60 mm (arbitrary), and the basis weight and thickness are measured. As an absorbent body, an NB pulp absorbent body is wrapped with a 15 gsm tissue and cut into 100 mm × 60 mm. And a surface sheet, a nonwoven fabric, and an absorber are joined by embossing.

The evaluation procedure is as follows. 1) Stack the acrylic plates so that the center of the hole matches the center of the sample. 2) Set the nozzle of the auto burette at a position 10 mm above the acrylic plate. 3) First artificial menstrual blood is dripped under the following conditions (rate: 95 ml / min, dripping amount: 3 ml). 4) Start the stopwatch from the start of dripping, and stop most of the artificial menstrual blood from the surface (when movement stops) and measure the absorption rate (A). 5) Simultaneously with the stop, another stopwatch is started. When the artificial menstrual blood in the surface sheet disappears (when the movement stops), the stopwatch is stopped and the total dry speed is measured (B). 6) Remove the acrylic board. 7) One minute after the start of dropping, the diffusion range, SKICON value (surface dryness) and color meter (whiteness) were measured (C, D, E). 8) The second artificial menstrual blood is dropped (rate: 95 ml / min, drop amount: 4 ml). 9) Start the stopwatch from the beginning of dripping, and stop most of the artificial menstrual blood from the surface (when movement stops) and measure the absorption rate (F). 10) At the same time as the stop, another stopwatch is started. When artificial menstrual blood disappears in the surface sheet (when the movement stops), stop and measure the total dry speed (G). 11) Remove the acrylic plate. 12) One minute after the start of dropping, the diffusion range, SKICON value (surface dryness), and color meter (whiteness) were measured (H, I, J). 13) A filter paper and an acrylic plate are placed on the sample, a 50 g / cm ² weight is further placed, and the sample is left for 1.5 minutes. 14) After 1.5 minutes, the weight of the filter paper was measured, and the first rewet rate measurement (K). 15) A filter paper and an acrylic plate are placed on the sample, and a 100 g / cm ² weight is further placed thereon and left for 1.5 minutes. 16) After 1.5 minutes, the weight of the filter paper was measured, and the second rewet rate measurement (L).

From the measurement results in the above A to L, the following evaluation results can be obtained.
1) First time (3 ml dripping): Absorption rate [sec] (A), Total dry rate [sec] (B), Diffusion range (MD × CD) [mm] (C), SKICON value [μS] (D) , Whiteness (E) [-] (E)
2) Second time (4 ml dripping (total 7 ml)): absorption rate [sec] (F), total drying rate [sec] (G), diffusion range (MD × CD) [mm] (H), SKICON value [μS ] (I), whiteness (E) [-] (J)
3) (1) Rewetting rate 1st time (under 50 g / cm ² ) (K), (2) Rewetting rate 2nd time (under 100 g / cm ² ) (L)

  The nonwoven fabric in this invention was manufactured and the dispersion index and the absorptivity were evaluated. The manufacturing conditions and evaluation results of the nonwoven fabric will be described below.

The nonwoven fabric in this invention was manufactured on condition of the following.
(1) Fiber structure Heat-shrinkable fiber A (melting point 145 ° C.) coated with a hydrophilic oil agent in a side-by-side structure of polyethylene-polypropylene copolymer and polypropylene, and a concentric core-sheath structure of high-density polyethylene and polypropylene And a heat-fusible fiber B (melting point 129 ° C.) coated with a hydrophilic oil agent, and a heat-fusible fiber C (melting point 129 ° C.) coated with a hydrophilic oil agent in an eccentric core-sheath structure of high-density polyethylene and polypropylene. A heat-fusible fiber D (melting point 119 ° C.) coated with a hydrophilic oil agent in a concentric core-sheath structure of low-density polyethylene and polypropylene was used as an average fiber fineness, average fiber length, fiber The nonwoven fabric in the present invention was manufactured by carrying out a card process at a mixing ratio and a set basis weight before shrinkage and performing a predetermined heat treatment.

(2) Manufacturing method The nonwoven fabric was manufactured with the 1st manufacturing method mentioned above. The conditions are as follows.
(A) The fiber structure shown above is opened by a card machine at a speed of 20 m / min to create a fiber web. Then, the fiber web is cut so that the width is 450 mm.
(B) The fiber web is cut onto MD300 mm × CD300 mm and placed on a 20-mesh lower air-permeable net as a lower support, and conveyed to a heating device in the melt heating process at a speed of 3 m / min.
(C) The temperature and hot air flow rate (10 Hz = 0.5 to 0.7 m / sec (60 Hz = 3.5 to 4.0 m / sec) shown in FIG. In the fusion heating process with a length of 1.5 m set in step 1)).
(D) A lower air-permeable net for conveyance and an upper air-permeable net for preventing scattering are arranged in the heating device in the contraction heating step. The fiber web carried out from the heating device in the fusion heating step is subjected to the temperature and hot air flow rate (10 Hz = 0.5 to 0.7 m / sec (60 Hz = 3.5 to 4.4) shown in Table 1 shown in FIG. (Corresponding to 0 m / sec)) is conveyed while being heated in the heating apparatus in the shrink heating process having a length of 1.5 m set in step 1). In the heating apparatus in the contraction heating process, hot air was blown alternately from above and below the fiber web, so that the fiber web was transported across the air from the lower net to the upper net.
(E) Various nonwoven fabrics were obtained by the above production method and production conditions.

(3) Measurement of mixing ratio (dispersion degree) of high density region and low density region As shown in Table 1 shown in FIG. 11, the dispersion index in various nonwoven fabrics was measured. The measurement result of the dispersion index is as shown in Table 1 of FIG. The dispersion index in Examples A-1 to F-1 was in the range of 310 to 705. It was in the range of 250 to 790 which is the range in the dispersion index. Here, Comparative Example A is an ultra-high density sheet that is composed only of heat-fusible fibers and has a substantially uniform roughness in the plane direction. The dispersion index in this comparative example A was 248. Comparative Example B is an ultra-low density sheet composed of only heat-fusible fibers and uniform in density in the plane direction. The dispersion index in this comparative example B was 167. Comparative Example C is a high-density sheet formed only from heat-shrinkable fibers. The dispersion index in Comparative Example C was 384.

(4) Evaluation of absorbency Examples D-2, E-1, and F-1, manufactured as described above, Comparative Example A (a high-density sheet having 100% heat-fusible fiber), and Comparative Example B (heat-sealing) Absorbency was evaluated when Comparative Example C (high-density sheet with 100% heat-shrinkable fiber) was used as the second sheet in the absorbent article.

As above-mentioned, the absorptive evaluation sample was created and the absorptivity was evaluated. The following same surface sheets were used as samples for absorption evaluation.
<Fiber structure of surface sheet>
A high-density polyethylene / polyethylene terephthalate core-sheath structure with an average fineness of 3.3 dtex and an average fiber length of 51 mm is a blend of fiber A coated with a hydrophilic oil agent and fiber B coated with a water repellent oil agent. . The mixing ratio of the fiber A and the fiber B is 70:30. The fiber basis weight is 40 g / m ² .
<Method for producing surface sheet>
A fiber web is created by opening with a card machine at a speed of 20 m / min, and the fiber web is cut so that the width is 450 mm. The fiber web is placed on the sleeve and conveyed onto a 20 mesh breathable net at a speed of 3 m / min. Thereafter, the inside of the oven set at a temperature of 125 ° C. and a hot air flow rate of 10 Hz is transported in about 30 seconds while being transported through the breathable net.
<Sample preparation for evaluation>
The prototype contents of the sample for absorption evaluation are the above-mentioned surface sheet, Examples D-2, E-1, F-1, Comparative Example A, Comparative Example B, and Comparative Example C, each having a length of 100 mm and a width of 70 mm. Cut. And with 500g / m ² fluff pulp adjusted to a thickness of 5mm on the absorbent core sandwiched between 16g / m ² tissue, hinge emboss set so that the narrowest part is 38mm The said nonwoven fabric which is an absorption core, a surface sheet, and a 2nd sheet | seat was joined, and the sample for evaluation was prepared.

<Measurement method and measurement result>
About each prepared said sample, absorptivity was evaluated along the procedure as described in description of the above-mentioned evaluation method. The measurement results are as shown in Table 2 of FIG. The evaluation results for each sample are summarized as follows.

The sample using Example D-2 had a permeation rate of 3.3 s when 3 ml was dropped, a drying rate of 5 s, and a surface diffusion of 14/38 mm. Further, the permeation rate when dropping 4 ml was 5.6 s, the total drying rate was 10 s, and the surface diffusion was 16 × 43 mm. The rewetting rate at a load of 51 gf / cm ² was 0.2%, and the rewetting rate at a load of 106 gf / cm ² was 0.4%.

The sample using Example E-1 was dried at a rate of 3.8 s when 3 ml was dropped, a drying rate of 9 s, and the surface diffusion was 12 × 36 mm. Further, the permeation rate at the time of dropping 4 ml was 6.8 s, the total drying rate was 11 s, and the surface diffusion was 14 × 44 mm. The rewetting rate at a load of 51 gf / cm ² was 0.2%, and the rewetting rate at a load of 106 gf / cm ² was 0.4%.

The sample using Example F-1 had a permeation rate of 4.7 s when 3 ml was dropped, a drying rate of 6 s, and a surface diffusion of 14 × 41 mm. Further, the permeation rate at the time of dropping 4 ml was 6.2 s, the total drying rate was 14 s, and the surface diffusion was 16 × 44 mm. The rewetting rate at a load of 51 gf / cm ² was 0.9%, and the rewetting rate at a load of 106 gf / cm ² was 1.0%.

The sample using Comparative Example A had a permeation rate of 5.1 s when 3 ml was dropped, a drying rate of 60 s, and was not dried, and the surface diffusion was 14 × 44 mm. Further, the permeation rate at the time of dropping 4 ml was 7.4 s, the total drying rate was not dried even at 60 s, and the surface diffusion was 17 × 47 mm. The rewet rate when 51 gf / cm ² was applied was 13%, and the rewet rate when 106 gf / cm ² was applied was 19%.

In the sample using Comparative Example B, the permeation rate when dropping 3 ml was 3.8 s, the drying rate was 60 s, and the surface diffusion was 14 × 32 mm. Further, the permeation rate at the time of dropping 4 ml was 5.8 s, the total drying rate was not dried even at 60 s, and the surface diffusion was 18 × 42 mm. The rewetting rate at a load of 51 gf / cm ² was 10%, and the rewetting rate at a load of 106 gf / cm ² was 15%.

The sample using Comparative Example C had a permeation rate of 4.3 s when 3 ml was dropped, a drying rate of 17 s, and a surface diffusion of 11 × 40 mm. Furthermore, when 4 ml was dropped, the permeation rate was 7.4 s, the total drying rate was 8 s, and the surface diffusion was 16 × 48 mm. The rewetting rate at a load of 51 gf / cm ² was 2.7%, and the rewetting rate at a load of 106 gf / cm ² was 4.8%.

  As shown in Table 2 of FIG. 12, the samples for evaluating absorbability using the nonwoven fabrics in Examples D-2, E-1, and F-1 as the second sheets are the nonwoven fabrics in Comparative Examples A, B, and C. Compared with the sample for evaluating the absorbency used as a sample, the penetration time is generally short, the total drying time is short, and the surface diffusion area is also small. Thereby, it can be said that the sample for absorptive evaluation using the nonwoven fabric of the example as the second sheet has low diffusibility when the liquid permeates, and does not hinder the transfer of the liquid from the top sheet to the absorber. Moreover, it can be said that it is excellent in the dryness of the surface, and it can be said that it has a dryness repeatedly. That is, it can be said that the nonwoven fabric in the present invention has low diffusibility when the liquid permeates, and does not hinder the transfer of the liquid from the topsheet to the absorber.

  Furthermore, as shown in Table 2, the samples for evaluating the absorbency using the nonwoven fabrics in Examples D-2, E-1, and F-1 as the second sheets are the nonwoven fabrics in Comparative Examples A, B, and C as the second sheets. Rewetting rate is low compared with the sample for absorbability evaluation used. The absorbent article using the nonwoven fabric in the present invention as the second sheet can be an absorbent article having a low rewet rate. Moreover, it can be said that the liquid from the surface sheet is suitably transferred to the absorber side.

It is a perspective view of the absorptive article in the present invention. It is XX sectional drawing in the absorbent article of FIG. It is a figure which shows the nonwoven fabric in sectional drawing of FIG. It is sectional drawing of the nonwoven fabric in this invention. It is an expanded sectional view of the nonwoven fabric in this invention. It is the top view and perspective view of the nonwoven fabric in this invention. It is a figure explaining the density structure of the nonwoven fabric in this invention. It is a figure explaining the absorption behavior of the liquid at the time of using the nonwoven fabric in this invention as a 2nd sheet | seat of an absorbent article. It is a figure explaining a 1st manufacturing method. It is a figure explaining a 2nd manufacturing method. It is Table 1 explaining the manufacturing result of the nonwoven fabric in an Example, and the measurement result of an average light absorbency. It is Table 2 explaining the evaluation result of the absorptivity of the nonwoven fabric in an Example.

Explanation of symbols

5 Nonwoven fabric 11 High density region 12 Low density region 110 Heat-shrinkable fiber 120 Heat-fusible fiber

Claims (17)

A non-woven fabric having a substantially uniform thickness including a heat-fusible fiber and a heat-shrinkable fiber and a heat-shrinkable fiber that is crimped at least in a heat-shrinkable state,
A high-density region consisting of the heat-shrinkable fibers mainly heat-shrinked and having a fiber density higher than the average fiber density in the nonwoven fabric;
A plurality of low density regions each consisting of the heat-fusible fibers mainly fused to each other and having a fiber density lower than the average fiber density,
Each of the plurality of high-density regions and the plurality of low-density regions is formed so as to be dispersed in a plane direction perpendicular to the thickness direction of the nonwoven fabric,
The nonwoven fabric formed so that all or a part of the plurality of low density regions communicates from one side to the other side in the thickness direction.   The nonwoven fabric according to claim 1, wherein the heat-shrinkable fiber exhibits heat-shrinkability at a temperature higher than a temperature at which the heat-fusible fiber can be melted.   The nonwoven fabric according to claim 1 or 2, wherein the heat-shrinkable fibers in the high-density region are crimped in a screwed manner and heat-shrinked so as to involve the heat-fusible fibers.   The nonwoven fabric according to any one of claims 1 to 3, wherein each of the plurality of low-density regions is formed around each of the composite high-density regions.   The heat-shrinkable fiber is thermally shrunk in a state where the shrinkage of the nonwoven fabric is suppressed by fusing the heat-fusible fiber to a fiber that contacts the heat-fusible fiber to form a network structure. The nonwoven fabric according to any one of claims 1 to 4, wherein the plurality of high-density regions and the plurality of low-density regions are formed.   The nonwoven fabric according to any one of claims 1 to 5, wherein a dispersion index indicating a degree of dispersion in the plurality of high-density regions and the plurality of low-density regions is 250 to 790. A heat-shrinkable fiber and a heat-shrinkable fiber, and a heat-shrinkable fiber having at least a heat-shrinkable state and having a substantially uniform thickness, the heat-shrinkable fiber being mainly heat-shrinkable A high density region made of shrinkable fibers and having a fiber density higher than the average fiber density in the nonwoven fabric, and a low density having a fiber density lower than the average fiber density mainly made of the heat-fusible fibers fused together. Each of the plurality of high-density regions and the plurality of low-density regions are formed so as to be dispersed in a plane direction perpendicular to the thickness direction of the nonwoven fabric. All or part of the method is a method for manufacturing a nonwoven fabric formed so as to communicate from one side to the other side in the thickness direction,
A transporting step of transporting a fiber web containing heat-fusible fibers and heat-shrinkable fibers and heat-shrinkable fibers having at least heat-shrinkable state to a predetermined heating device;
A shrinkage heating step of heat-treating the fiber web at a temperature at which the heat-shrinkability of the heat-shrinkable fibers can be expressed by the heating device while conveying the fiber web in a predetermined direction,
The nonwoven fabric manufacturing method which adjusts the aspect of the said high density area | region and the said low density area | region by adjusting the conveyance speed of the said fiber web in the said conveyance process and / or the conveyance speed of the said fiber web in the said shrink heating process.   The fiber web transport speed in the shrink heating step is such that the ratio of the fiber web transport speed in the shrink heating step to the fiber web transport speed in the transport step is the fiber at the heating temperature in the shrink heating step. The nonwoven fabric manufacturing method according to claim 7, wherein the nonwoven fabric is adjusted so as to be larger than a heat shrinkage ratio of the web.   This is a step prior to the shrink heating step, in order to regulate the degree of freedom of the heat shrinkable fibers by reducing the thickness of the fiber web, wherein the heat fusible fibers are substantially melted. And a preheating step of heat-treating at a temperature at which the heat-shrinkable fibers are not substantially heat-shrinkable.   A fusion heating step that is a step prior to the shrink heating step, wherein the heat fusible fiber is meltable and heated at a temperature at which the heat shrinkable fiber does not substantially heat shrink. Item 10. The nonwoven fabric production method according to any one of Items 7 to 9. In the fusion heating step, the heat-fusible fiber is melted and fused to a fiber in contact with the fusible fiber to form a network structure,
In the state in which the network structure is formed and the shrinkage of the fiber web is suppressed by the shrinkage heating step, the heat-shrinkable fibers are thermally shrunk to form the plurality of high-density regions and the plurality of low-density regions. The method for producing a nonwoven fabric according to claim 10.   The nonwoven fabric production according to any one of claims 7 to 11, wherein inhibition of shrinkage in the heat-shrinkable fibers contained in the fiber web is suppressed by reducing friction applied to the fiber web in the shrink heating step. Method. In the shrink heating step, the fibrous web includes a breathable first support member and a breathable second support member disposed substantially parallel to the upper side in the vertical direction at a predetermined distance from the first support member. Conveyed in a state of being placed between,
By blowing hot air at a predetermined temperature from the lower side in the vertical direction of the first support member, and blowing hot air at a predetermined temperature from the upper side in the vertical direction of the second support member, all or part of the fiber web is The nonwoven fabric manufacturing method of Claim 12 which heat-processes this fiber web in the state spaced apart from the 1st supporting member and / or the said 2nd supporting member.   The nonwoven fabric manufacturing method of Claim 13 which heat-processes in the state which loosened the said fiber web. At least a part of the liquid-permeable top sheet, the liquid-impermeable back sheet, the liquid-retaining absorbent disposed between the top sheet and the back sheet, the top sheet and the absorbent One or a plurality of second sheets disposed between and an absorbent article,
Each of the one or more second sheets is a non-woven fabric having a substantially uniform thickness including a heat-fusible fiber and a heat-shrinkable fiber and a heat-shrinkable fiber that is crimped at least in a heat-shrinkable state. The heat-shrinkable fibers that are mainly heat-shrinkable and the high-density region that is higher in fiber density than the average fiber density in the nonwoven fabric, and the heat-fusible fibers that are mainly fused to each other. A non-woven fabric having a plurality of low-density regions each having a fiber density lower than the fiber density,
Each of the plurality of high-density regions and the plurality of low-density regions in the nonwoven fabric is formed so as to be dispersed in a plane direction perpendicular to the thickness direction in the nonwoven fabric, and all or in the plurality of low-density regions A part of the absorbent article is formed so as to communicate from one side to the other side in the thickness direction.   The second sheet according to claim 15, wherein an average fiber density in the second sheet is higher than an average fiber density in the top sheet, and a fiber density in the high-density region is lower than an average fiber density in the absorber. Absorbent article.   The absorbent article according to claim 15 or 16, comprising two second sheets, wherein the two second sheets have different contents in the high-density region and the low-density region, respectively.

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