JP2017042607A - Non-woven fabric and absorbent article equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-woven fabric which can keep the control of permeability of a liquid after plural times of liquid permeation.SOLUTION: A non-woven fabric 10 is configured to generate a first region 11 and a second region 12, that have constituent fibers of different hydrophilic properties, in a thickness direction T when 90 g of artificial urine permeates at a speed of 5.0 g/sec under a non-pressurization condition. The first region 11 is a region including a surface of the non-woven fabric 10, and the second region 12 is a region adjacent to the first region 11 when viewed in the thickness direction T of the non-woven fabric 10. When the hydrophilic properties are represented by a contact angle with water, the contact angle of the constituent fibers in the first region 11 is greater than a contact angle of the constituent fibers in the second region 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nonwoven fabric and an absorbent article including the same.

  In various absorbent articles such as disposable diapers and sanitary napkins, the body fluid excreted from the wearer is absorbed and held by the absorbent body, and the held body fluid is prevented from returning to the wearer's body side. It is demanded. The phenomenon in which the body fluid held in the absorber returns is generally referred to as wetback, and various proposals have been made to prevent this. As one approach for preventing the occurrence of wetback, there is known a method for controlling the hydrophilicity of a surface sheet, which is a member located on the skin-facing surface side of the absorber, that is, the degree of familiarity with water.

  For example, in Patent Document 1, the surface sheet of the absorbent article has two layers, an upper layer positioned on the liquid-receiving side surface and a lower layer positioned on the absorber side, and the upper layer and the lower layer are formed of continuous filaments. It is described that the lower layer has higher hydrophilicity than the lower layer. Patent Document 2 describes a surface sheet of an absorbent article in which concave portions and convex portions are alternately formed by embossing in a predetermined pattern. The concave portion has hydrophilicity, the convex portion has hydrophobicity, the concave portion is a high density region having a relatively high fiber density, and the convex portion is a low density region having a relatively low fiber density. ing. According to this surface sheet, the concave portion is not provided with an opening or the like, and has improved hydrophilicity by providing hydrophilicity, so that the bodily fluid absorbed by the absorber is subsequently subjected to pressure. Even in this case, it is described in the same document that reversal is prevented.

JP 2002-65738 A JP 2009-268559 A

  In the conventional techniques including the techniques described in Patent Documents 1 and 2, the prevention of the occurrence of wetback has been studied by paying attention to the hydrophilicity of the surface sheet before the body fluid passes through. However, the body fluid excreted in the absorbent article is not limited to one time, and excretion occurs multiple times as the wearing time increases. And since the processing agent, such as a hydrophilizing agent applied to the surface sheet, flows out together with the body fluid every time it is excreted, the hydrophilicity of the surface sheet changes accordingly. Prevention of the occurrence of wetback by paying attention to this change has not been studied.

  Accordingly, an object of the present invention is to improve a nonwoven fabric and an absorbent article having the nonwoven fabric, and more specifically, a nonwoven fabric capable of maintaining liquid permeability control even after a plurality of liquid passages and an absorbent having the same. To provide an article.

  As a result of intensive studies by the inventor to solve the above-mentioned problems, when the liquid is allowed to permeate through a nonwoven fabric having two or more layers having different hydrophilicities along the thickness direction, the upper layer side which is a layer on the liquid receiving side Not only the region located on the lower layer side, which is the layer on the absorber side, but also the region located on the lower layer side becomes more hydrophobic than the region located on the upper layer side. I found out that

The present invention has been made on the basis of the above findings, and the first region in which the hydrophilicity of the constituent fibers is different from each other when 90 g of artificial urine is passed at a rate of 5.0 g / sec under no pressure condition. And a non-woven fabric in which the second region is formed along the thickness direction,
The first region is a region including the surface of the nonwoven fabric, the second region is a region adjacent to the first region when viewed along the thickness direction of the nonwoven fabric,
When the hydrophilicity is represented by a contact angle with water, a nonwoven fabric is provided in which the contact angle of the constituent fibers in the first region is larger than the contact angle of the constituent fibers in the second region.

  Moreover, this invention provides the absorbent article which provided the said nonwoven fabric and distribute | arranged so that the 1st area | region in this nonwoven fabric might face a wearer's skin.

  According to the present invention, there is provided a nonwoven fabric that can maintain liquid permeability control even after a plurality of times of liquid passage. In the absorbent article using the nonwoven fabric, the occurrence of wetback is effectively prevented.

FIG. 1 is a cross-sectional view in the thickness direction showing one embodiment of the nonwoven fabric of the present invention. Fig.2 (a) is a perspective view of an example of the nonwoven fabric shown in FIG. 1, and FIG.2 (b) is a perspective view of another example of the nonwoven fabric shown in FIG. FIG. 3 is a cross-sectional view in the thickness direction showing another embodiment of the nonwoven fabric of the present invention. FIG. 4 is a cross-sectional view in the thickness direction showing still another embodiment of the nonwoven fabric of the present invention. FIG. 5 is a cross-sectional view in the thickness direction showing still another embodiment of the nonwoven fabric of the present invention.

  The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 is a cross-sectional view in the thickness direction showing one embodiment of the nonwoven fabric of the present invention. The nonwoven fabric 10 shown in the figure is composed of a laminated structure including a first nonwoven fabric layer 11 and a second nonwoven fabric layer 12. In the nonwoven fabric 10, the 1st nonwoven fabric layer 11 and the 2nd nonwoven fabric layer 12 are joined partially, and the several junction part 13 is formed. The 1st nonwoven fabric layer 11 protrudes in the direction away from the 2nd nonwoven fabric layer 12 in parts other than the junction part 13. As shown in FIG. Thereby, a plurality of convex portions 14 are formed on the nonwoven fabric 10. A space 16 defined by the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 is formed inside the convex portion 14. A concave portion 15 is formed between adjacent convex portions 14, and the joint portion 13 is located in the concave portion 15. As a result, the nonwoven fabric 10 has an uneven structure on the surface of the first nonwoven fabric layer 11. On the other hand, the surface of the second nonwoven fabric layer 12 of the nonwoven fabric 10 is generally flat.

  FIG. 1 is a view of the nonwoven fabric 10 as viewed along its thickness direction. As shown in FIG. 2A, the convex portions 14 of the nonwoven fabric 10 can be arranged in a dotted pattern. In detail, in the nonwoven fabric 10, the convex part 14 and the recessed part 15 are alternately arrange | positioned along one direction X in the surface. At the same time, the convex portions 14 and the concave portions 15 are alternately arranged along the Y direction orthogonal to the X direction. The nonwoven fabric having such a structure can be produced by, for example, a method described in JP-A No. 2004-174234.

  Instead of the structure shown in FIG. 2A, the structure shown in FIG. 2B can be adopted. In the nonwoven fabric 10 shown in FIG. 2B, convex portions 14 extending along one direction X in the plane and concave portions 15 extending along the X direction alternately along the Y direction orthogonal to the X direction. It has a structure arranged in In any of the embodiments shown in FIGS. 2A and 2B, a space 16 is formed inside the convex portion 14.

  The nonwoven fabric 10 is characterized in that the hydrophilic state after passing artificial urine through the nonwoven fabric 10 differs in the thickness direction T of the nonwoven fabric 10. Specifically, in the nonwoven fabric 10, when artificial urine is passed through, a first region and a second region in which the hydrophilicity of the constituent fibers are different from each other are generated along the thickness direction T. The first region is a region including the surface of the nonwoven fabric 10. On the other hand, the second region is a region adjacent to the first region when viewed along the thickness direction T of the nonwoven fabric 10. “Adjacent” is a state in which no other region is interposed between the two regions of interest and the two regions are in direct contact with each other. Even if there is a space between the two regions, when the nonwoven fabric 10 is used, for example, when the nonwoven fabric 10 is incorporated into an absorbent article and the absorbent article is attached (at the time of liquid return), the space The case where the area is crushed and the two areas are in direct contact with each other is also included in the adjacent area. In the nonwoven fabric 10, the 1st nonwoven fabric layer 11 is an area | region corresponding to a 1st area | region. The second nonwoven fabric layer 12 is a region corresponding to the second region.

  The first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 are different from each other in hydrophilicity of their constituent fibers after passing the artificial urine through the nonwoven fabric 10. “Hydrophilicity” refers to the property of compatibility with water. High hydrophilicity tends to be compatible with water, and highly hydrophilic fibers tend to wet and spread on the surface. If the hydrophilicity is low, the compatibility with water is not good, and the fibers having low hydrophilicity tend to be repelled on the surface. In the present invention, the degree of hydrophilicity of the fiber is quantitatively expressed by the contact angle with water. The contact angle with water is measured by the method described later. Low hydrophilicity is synonymous with a large contact angle, and high hydrophilicity is synonymous with a small contact angle.

  And in the nonwoven fabric 10, the contact angle of the constituent fiber of the 1st nonwoven fabric layer 11 which is a 1st area | region in the state after a liquid flow is more than the contact angle of the constituent fiber of the 2nd nonwoven fabric layer 12 which is a 2nd area | region. Is also getting bigger. That is, the first nonwoven fabric layer 11 is lower in hydrophilicity than the second nonwoven fabric layer 12 in the state after liquid passage. As a result, the hydrophilicity of the constituent fibers increases from the first nonwoven fabric layer 11 toward the second nonwoven fabric layer 12 along the thickness direction T when viewed as a whole of the nonwoven fabric 10 after liquid passage. A gradient is formed. Thus, in the nonwoven fabric 10, control of the liquid permeability is maintained even after a plurality of times of liquid passage. In particular, since the hydrophilic gradient is formed along the thickness direction T of the nonwoven fabric 10, the nonwoven fabric 10 is used as a surface sheet of the absorbent article, and the first nonwoven fabric layer 11 in the nonwoven fabric 10 is used as the skin of the wearer. In the absorbent article arranged so as to oppose the liquid, the wetback of the liquid once absorbed and held in the absorbent body is effectively prevented by the nonwoven fabric 10 having a hydrophilic gradient.

  In contrast to the nonwoven fabric of the present invention, in a conventional nonwoven fabric having two or more regions having different hydrophilic properties along the thickness direction, when a liquid such as artificial urine is permeated through the nonwoven fabric, on the upper layer side The inventor found for the first time that the region located on the lower layer side becomes more hydrophobic than the region located. Therefore, when this type of conventional nonwoven fabric is used as, for example, a surface sheet of an absorbent article, the hydrophilicity gradient of liquid movement from the absorber side toward the surface side of the surface sheet is higher because the portion closer to the surface has higher hydrophilicity. And wet back of the liquid once absorbed and held in the absorber is likely to occur.

  The above-mentioned artificial urine flow means that 90 g of artificial urine is passed through the nonwoven fabric 10 at a rate of 5.0 g / sec under no-pressure condition under the condition that the nonwoven fabric 10 is placed on the absorbent body. Means that. The artificial urine is supplied to the nonwoven fabric 10 by using a liquid injection pump (manufactured by ISMATEC, MCP-J) by guiding the liquid discharge port 10 mm above the nonwoven fabric placed on the absorbent body with a silicon tube. As the absorber, the surface sheet was removed from the Marys (registered trademark) tape type S size manufactured by Kao Corporation manufactured in 2013, and the absorber was used. The supply amount of 90 g assumes the average excretion amount of infants. The supply rate of 5.0 g / sec assumes the urinary excretion speed during excretion of infants. The composition of artificial urine was 1.940% by weight of urea, 0.795% by weight of sodium chloride, 0.110% by weight of magnesium sulfate, 0.062% by weight of calcium chloride, 0.197% by weight of potassium sulfate, red No. 2 (dye ) 0.010% by mass, water (about 96.88% by mass) and polyoxyethylene lauryl ether (about 0.07% by mass) with the surface tension adjusted to 53 ± 1 dyne / cm (23 ° C.) is there.

  The method for measuring the contact angle with water as described above is as follows. After passing artificial urine through the nonwoven fabric 10 under the above-described conditions, fibers are taken out from the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 in the nonwoven fabric 10 and the contact angle of water with the fibers is measured. In addition, the present inventor has confirmed that no change in the contact angle is observed for about half a day after the artificial urine is passed, and in the examples and comparative examples, the contact after the passage by measuring within half a day. Got horns. As a measuring device, an automatic contact angle meter MCA-J manufactured by Kyowa Interface Science Co., Ltd. is used. Distilled water is used to measure the contact angle. The amount of liquid discharged from an ink jet type water droplet discharge part (manufactured by Cluster Technology, Inc., pulse injector CTC-25 having a discharge part pore diameter of 25 μm) is set to 20 picoliters, and a water drop is dropped directly above the fiber. The state of dripping is recorded on a high-speed recording device connected to a horizontally installed camera. The recording device is preferably a personal computer incorporating a high-speed capture device from the viewpoint of image analysis later. In this measurement, an image is recorded every 17 msec. In the recorded video, the first image of water droplets on the fibers taken out from the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 is attached to the attached software FAMAS (software version is 2.6.2, analysis method is liquid Drop method and analysis method are θ / 2 method, image processing algorithm is non-reflective, image processing image mode is frame, threshold level is 200, and curvature correction is not performed). The angle between the surface touching the fiber and the fiber is calculated as the contact angle. The fibers taken out from the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 are cut into a fiber length of 1 mm, and the fibers are placed on a sample table of a contact angle meter and kept horizontal. Two different contact angles are measured for each fiber. N = 5 contact angles are measured to one decimal place, and a value obtained by averaging a total of 10 measured values (rounded to the first decimal place) is defined as the contact angle.

  In order to control the hydrophilicity of the nonwoven fabric 10 after the passage of artificial urine as described above, a fiber treatment agent may be applied in advance to the fibers constituting the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12. preferable. The fiber treatment agent is a substance that can adhere to the surface of the fiber and change the hydrophilicity of the fiber, and generally a surfactant is preferably used. In particular, in the state before the passage of artificial urine, a fiber treatment agent in which the contact angle of the constituent fibers of the first nonwoven fabric layer 11 is larger than the contact angle of the constituent fibers of the second nonwoven fabric layer 12, It is preferable to apply to the constituent fibers of the nonwoven fabric layer in advance. By doing so, a hydrophilic gradient is already formed along the thickness direction T of the nonwoven fabric 10 before the nonwoven fabric 10 is allowed to pass through, and the hydrophilic gradient is maintained even after the fluid is passed. As a result, when the nonwoven fabric 10 is used as a top sheet of an absorbent article, the occurrence of wetback is more effectively prevented.

  The relative hydrophilicity of the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 is as described above. The contact angle of the constituent fibers of the first nonwoven fabric layer 11 is 80 degrees after the liquid is passed through. Preferably, the angle is 85 ° or more, more preferably 90 ° or more. Moreover, it is preferable that it is 100 degrees or less, More preferably, it is 97 degrees or less, More preferably, it is 94 degrees or less. The contact angle of the constituent fibers of the first nonwoven fabric layer 11 is preferably 80 degrees or more and 100 degrees or less, more preferably 85 degrees or more and 97 degrees or less, and still more preferably 90 degrees or more and 94 degrees or less. .

  On the other hand, the contact angle of the constituent fibers themselves of the second nonwoven fabric layer 12 is preferably 65 degrees or more after liquid passing, on condition that the contact angle of the constituent fibers of the first nonwoven fabric layer 11 is smaller. Preferably it is 70 degree | times or more, More preferably, it is 75 degree | times or more. Moreover, it is preferable that it is 90 degrees or less, More preferably, it is 87 degrees or less, More preferably, it is 84 degrees or less. The contact angle of the constituent fibers of the second nonwoven fabric layer 12 is preferably 65 degrees or more and 90 degrees or less, more preferably 70 degrees or more and 87 degrees or less, and further preferably 75 degrees or more and 84 degrees or less after liquid passage. .

  After the liquid flow, the difference between the contact angle of the constituent fibers of the first nonwoven fabric layer 11 as the first region and the contact angle of the constituent fibers of the second nonwoven fabric layer 12 as the second region (the former-the latter) is the wet From the viewpoint of reducing the back amount and suppressing the return of the liquid to the user, it is preferably greater than 0 degree, more preferably 3 degrees or more, and even more preferably 5 degrees or more. Basically, the larger the contact angle difference, the better. However, it is preferable to suppress the hydrophilicity to some extent in order to allow the liquid to permeate the first nonwoven fabric layer 11 quickly, and from the second nonwoven fabric layer 12 to the absorbent body. In order to control the liquid transferability of the liquid, it is preferable that it is hydrophobic to some extent, so the upper limit of the contact angle difference is preferably 30 degrees or less, more preferably 25 degrees or less, and even more preferably 20 degrees or less. is there.

  The above is the explanation about the contact angles of the constituent fibers of the first and second nonwoven fabric layers 11 and 12 after the liquid passage. The contact angles of the constituent fibers of the first and second nonwoven fabric layers 11 and 12 before the fluid passage. Is preferably as follows. That is, the contact angle of the constituent fibers of the first nonwoven fabric layer 11 is preferably 75 ° or more before passing through, more preferably 78 ° or more, and still more preferably 81 ° or more. Also, it is preferably less than 90 degrees, more preferably 87 degrees or less, and still more preferably 84 degrees or less. The contact angle of the constituent fibers of the first nonwoven fabric layer 11 is preferably 75 degrees or more and less than 90 degrees before passing, more preferably 78 degrees or more and 87 degrees or less, and still more preferably 81 degrees or more and 84 degrees or less. .

  It is preferable that the contact angle of the constituent fibers of the first nonwoven fabric layer 11 before the liquid passage is smaller than the contact angle of the constituent fibers of the first nonwoven fabric layer 11 after the liquid passage.

  On the other hand, on the condition that the contact angle of the constituent fibers of the second nonwoven fabric layer 12 is smaller than the contact angle of the constituent fibers of the first nonwoven fabric layer 11, it is preferably 60 degrees or more before liquid passing, more preferably It is 65 degrees or more, more preferably 70 degrees or more. Moreover, it is preferable that it is 85 degrees or less, More preferably, it is 80 degrees or less, More preferably, it is 75 degrees or less. The contact angle of the constituent fibers of the second nonwoven fabric layer 12 is preferably 60 degrees or more and 85 degrees or less, more preferably 65 degrees or more and 80 degrees or less, and further preferably 70 degrees or more and 75 degrees or less before liquid passage. .

  The difference between the contact angle of the constituent fibers of the first nonwoven fabric layer 11 that is the first region and the contact angle of the constituent fibers of the second nonwoven fabric layer 12 that is the second region (the former-the latter) before the liquid flow is From the viewpoint of reducing the back amount and suppressing the return of the liquid to the user, it is preferably greater than 0 degree, more preferably 3 degrees or more, and even more preferably 5 degrees or more. Basically, the larger the contact angle difference is, the better. However, if the first nonwoven fabric layer 11 is made too hydrophobic, liquid passage may be hindered. If the second nonwoven fabric layer 12 is made strongly hydrophilic, liquid retention Is excessively increased and may impede liquid migration to the absorber, so the upper limit of the contact angle difference is preferably 30 degrees or less, more preferably 25 degrees or less, and still more preferably. It is 20 degrees or less.

  In order to control the degree of hydrophilicity of each nonwoven fabric layer 11 and 12 as described above, it is important to appropriately select the type of fiber treatment agent applied to each nonwoven fabric layer 11 and 12. In particular, the main component of the fiber treatment agent applied to the constituent fibers in the first region is preferably different from the main component of the fiber treatment agent applied to the constituent fibers in the second region. The “main component” refers to a component having a content ratio of 10% by mass or more with respect to all components of the fiber treatment agent in the fiber treatment agent in a state before being applied to the fiber. The amount of the fiber treatment agent attached to the fibers is generally 2% by mass or less. The reason why the adhesion amount is set so low is that if an excessive amount is applied, a machine for manufacturing is contaminated or the user's skin becomes sticky. Therefore, in the fiber treatment agent to which only a very small amount is applied as described above, a sufficient function on the nonwoven fabric such as hydrophilicity is not exhibited unless the ratio of the main component in the fiber treatment agent is set to 10% by mass or more. For example, when the proportion of the main component is 10% by mass, the proportion of the main component imparted to the fiber is only 0.2% by mass with respect to the fiber treatment agent. Therefore, there may be two or more main components. When two or more kinds of main components are present, it is preferable that the main components are different between the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 regardless of which main component is focused. As long as the main components are different, the minor component in the fiber treatment agent applied to the constituent fibers of the first nonwoven fabric layer 11 and the minor component in the fiber treatment agent applied to the constituent fibers of the second nonwoven fabric layer 12 It is not hindered that the types of and match.

  The main component (hereinafter also referred to as “first region main component”) of the fiber treatment agent applied to the constituent fibers of the first nonwoven fabric layer 11 (first region) and the second nonwoven fabric layer 12 (second region). When the main component of the fiber treatment agent applied to the constituent fibers (hereinafter also referred to as “second region main component”) is made different, the extent to which both main components are eluted in water upon contact with water is different. It is preferable. In particular, it is preferable that the first region main component has a greater degree of elution into water than the second region main component. By adopting the first region main component and the second region main component having such properties, the second nonwoven fabric layer 12 has higher hydrophilicity than the first nonwoven fabric layer 11 after repeated liquid passage. , Wetback is effectively prevented.

  From the viewpoint of more effectively preventing wetback, the constituent fibers of the second nonwoven fabric layer 12 (second region) are different from the main components applied to the constituent fibers of the first nonwoven fabric layer 11 (first region). The main component is preferably applied in an amount of 40% by mass or more, more preferably 50% by mass or more.

  In particular, with respect to the second nonwoven fabric layer 12, one of the main components of the fiber treatment agent applied to the constituent fibers is a polyorganosiloxane having a hydrophilic group. Since hydrophilicity can be maintained higher than a constituent fiber, it is preferable. Examples of the hydrophilic group include a hydroxyl group, a polyoxyalkylene group, an amino group, a diamino group, a polyglyceryl group, an epoxy group, a carbinol group, a carboxyl group, a diol group, and a methacryl group. These hydrophilic groups can be used alone or in combination of two or more. Among the hydrophilic groups, it is preferable to use a polyoxyalkylene group or a polyglyceryl group from the viewpoint of imparting sufficient hydrophilicity to the fiber surface and improving dispersibility in water and handling properties as a fiber treatment agent. . In particular, the polyoxyalkylene-modified silicone modified with a polyoxyalkylene group can maintain higher hydrophilicity than the constituent fibers of the first nonwoven fabric layer 11 even after liquid passage (that is, keep the contact angle small). It is preferable. Polyoxyalkylene-modified silicone is a polymer compound obtained by modifying silicone with polyoxyalkylene. As the polyoxyalkylene used for modification, those having a lower alkylene group having 2 to 4 carbon atoms are preferably used, and specific examples thereof include polyoxyethylene (hereinafter also referred to as “POE”) and polyoxypropylene. (Hereinafter also referred to as “POP”) and polyoxybutylene (hereinafter also referred to as “POB”). A polyoxyalkylene containing a plurality of POE, POP and POB can also be used. The number of repeating oxyalkylene groups in the polyoxyalkylene group is preferably 3 or more, more preferably 5 or more, and still more preferably 7 or more. Moreover, it is preferably 40 or less, more preferably 30 or less, and still more preferably 20 or less. The number of repeating oxyalkylene groups is preferably 3 or more and 40 or less, more preferably 5 or more and 30 or less, and still more preferably 7 or more and 20 or less. A commercially available product may be used as the polyoxyalkylene-modified silicone. Examples of such commercially available products include “Shin-Etsu Silicone KF-6012” and “Shin-Etsu Silicone X-22-4515” manufactured by Shin-Etsu Chemical Co., Ltd.

  The proportion of the polyoxyalkylene-modified silicone contained in the fiber treatment agent applied to the constituent fibers of the second nonwoven fabric layer 12 is preferably 15% by mass or more, more preferably 20% by mass or more, and 25% by mass. It is still more preferable that it is above. Further, it is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less. The proportion of the polyoxyalkylene-modified silicone contained in the fiber treatment agent is preferably 15% by mass to 60% by mass, more preferably 20% by mass to 50% by mass, and more preferably 25% by mass to 40% by mass. More preferably, it is as follows.

  Examples of the substance used as a main component in addition to the polyoxyalkylene-modified silicone include, for example, alkali metal salts of alkyl phosphate esters, POE polyhydric alcohol fatty acid esters, alkyl betaines, alkyl sulfonic acids, alkyl sulfuric acids, dialkyl sulfonic acids, POE alkylamide and the like can be mentioned. Examples of the minor component that is not the main component include alkylhydroxysulfobetaine, imidazolium type cationic surfactant, polyethylene glycol, and polypropylene glycol.

  Concerning the fiber treatment agent to be applied to the constituent fibers of the first nonwoven fabric layer 11, the composition of the first and second nonwoven fabric layers 11, 12 after the passage is that it contains a hydrophobic substance as a main component. This is preferable because the hydrophilicity of the fibers is easily different from each other. Specifically, the main component of the fiber treatment agent is hydrocarbon oil, fluorine oil, fatty acid ester, polyoxyalkylene-modified silicone, polyorganosiloxane, and nonionic and ionic surfactants having an alkyl group having 16 or more carbon atoms. It is preferably at least one selected from the group consisting of agents. Among these substances, it is particularly preferable to use at least one selected from the group consisting of polyoxyalkylene-modified silicones, polyorganosiloxanes, nonionic and ionic surfactants having an alkyl group having 16 or more carbon atoms. It is preferable to use at least one selected from the group consisting of polyorganosiloxanes, nonionic and ionic surfactants having an alkyl group having 16 or more carbon atoms.

  In the fiber treatment agent to be applied to the constituent fibers of the first nonwoven fabric layer 11, examples of the minor component that is not a main component include alkylsulfonic acid, alkylsulfuric acid, dialkylsulfonic acid, alkylhydroxysulfobetaine, and imidazolium type cationic surface activity. Agents, polyethylene glycol, polypropylene glycol and the like.

  Identification and quantification of the type of the fiber treatment agent in the nonwoven fabric to which the fiber treatment agent is applied can be performed by, for example, the following method. If the nonwoven fabric is a surface sheet of an absorbent article, collect the required amount of product, peel off the surface sheet of the product from the absorber, and use a solvent such as methanol or ethanol from the peeled surface sheet. Extract the fiber treatment agent. After extracting the fiber treating agent, the residue is subjected to column separation, GPC, GC-MS, LC-MS, NMR, IR, solvent extraction using solubility in a solvent, recrystallization with a mixed solvent, and elemental analysis. Thus, the structure of the substance is identified and quantified. The component contained by 10 mass% or more with respect to the total amount is the main component described above.

  In order to apply a fiber treatment agent to the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12, for example, a case where a fiber treatment agent is applied to fibers before being made into a nonwoven fabric, and a case where a fiber treatment agent is applied to the nonwoven fabric after being made into a nonwoven fabric. There is. As a specific method for applying the fiber treatment agent, for example, immersing the fiber or the nonwoven fabric in the fiber treatment agent, spraying the fiber treatment agent on the fiber or the nonwoven fabric, or fiber or nonwoven fabric using various rolls such as a kiss roll. Coating by various printing methods such as mechanical coating, inkjet, gravure, screen, flexo and the like. After applying the fiber treatment agent, the fiber treatment agent can be adhered to the surface of the constituent fibers by removing an excessive amount of the fiber treatment agent and subsequently removing volatile components by heat drying or natural drying.

  FIG. 3 shows another embodiment of the nonwoven fabric of the present invention. Similarly to the nonwoven fabric of the embodiment shown in FIG. 1, the nonwoven fabric 10 shown in FIG. 1 has a laminated structure of a first nonwoven fabric layer 11 and a second nonwoven fabric layer 12. However, in the nonwoven fabric 10 of this embodiment, in the nonwoven fabric of the embodiment shown in FIG. 1, no space is formed inside the convex portion 14, and the inside of the convex portion 14 is filled with fibers. Moreover, in the recessed part 15 located between the adjacent convex parts 14, the surface of the 2nd nonwoven fabric layer 12 is exposed.

  The non-woven fabric 10 of the embodiment shown in FIG. 4 also has a laminated structure of the first non-woven fabric layer 11 and the second non-woven fabric layer 12 like the non-woven fabric described so far. However, each surface of the nonwoven fabric 10 of the present embodiment is generally flat and does not have an uneven structure. In order to ensure the liquid permeability of the nonwoven fabric 10 as a whole, it is preferable that the nonwoven fabric layers 11 and 12 are joined discontinuously over the entire area of the opposing surfaces. Since there is no difference in appearance between the front and back surfaces of the nonwoven fabric 10 of the present embodiment, which side of the nonwoven fabric layer is attributed to the first nonwoven fabric layer 11 is determined by the contact angle of the constituent fibers in the nonwoven fabric 10 after liquid passage. To do. Specifically, the non-woven fabric layer on which fibers having a larger contact angle exist is assigned to the first non-woven fabric layer 11.

  The nonwoven fabric 10 of the embodiment shown in FIG. 5 is of a single layer, unlike the nonwoven fabric of the previous embodiments. In the nonwoven fabric 10, after the artificial urine is passed through the nonwoven fabric 10, the first region 11 </ b> A and the second region 12 </ b> A having different hydrophilicity of the constituent fibers are formed along the thickness direction T. The first region 11 </ b> A is a region including one surface of the nonwoven fabric 10. The second region 12 </ b> A is a region adjacent to the first region 11 </ b> A when viewed along the thickness direction T of the nonwoven fabric 10. In the nonwoven fabric 10, the contact angle of the constituent fibers in the first region 11A is larger than the contact angle of the constituent fibers in the second region 12A after the liquid is passed. As a result, the hydrophilic gradient of the constituent fibers increases from the first region 11A toward the second region 12A along the thickness direction T when viewed in the entire nonwoven fabric 10 after liquid passage. It is formed.

  In the nonwoven fabric 10 of this embodiment, which side is assigned to the first region 11A is determined in the same manner as in the embodiment shown in FIG.

  In order to manufacture the nonwoven fabric 10 of this embodiment, for example, the first fiber treatment agent is applied from one surface of the raw nonwoven fabric, and the second fiber treatment agent having a composition different from that of the first fiber treatment agent is applied from the other surface. That's fine. Alternatively, a first web made of fibers to which the first fiber treatment agent is applied and a second web made of fibers to which the second fiber treatment agent having a composition different from that of the first fiber treatment agent is laminated, Next, the laminated web may be made into a nonwoven fabric. Alternatively, the first fiber treatment agent is applied to the first web, the second fiber treatment agent having a composition different from that of the first fiber treatment agent is applied to the second web, and then both the webs are laminated, and then the laminated web is formed. What is necessary is just to use a nonwoven fabric.

  As the fiber resin constituting the nonwoven fabric in each of the above embodiments, various thermoplastic resins having fiber-forming properties can be used. Examples of such resins include polyolefin resins such as polyethylene (PE) and polypropylene, polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate, vinyl resins such as polystyrene and polyvinyl chloride, and polyacrylic acid. Or the polyacrylic acid type | system | group or polymethacrylic acid type resin which consists of polymethacrylic acid or those esters is mentioned. These resins can be used alone or in combination of two or more. When two or more resins are used in combination, a fiber having a single structure is produced from a blend of two or more resins, and a fiber having a composite structure such as a core-sheath type or side-by-side type fiber is used. The case of manufacturing is included. When the nonwoven fabric 10 of this embodiment is manufactured by air-through treatment of a laminated web, for example, from the viewpoint of air-through treatment conditions and physical properties of the nonwoven fabric, the core is a polyester resin, and the sheath is a polyolefin resin having a lower melting point than the core. It is preferable to use a fiber having a core-sheath type composite structure.

  In the embodiment shown in FIGS. 1 to 4, the types of constituent fibers may be the same or different between the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12. The same applies to the basis weight, and the basis weight may be the same or different between the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12.

  According to this invention, the absorbent article provided with the nonwoven fabric demonstrated so far is also provided. In this absorbent article, it is preferable to arrange the first nonwoven fabric layer 11 (first region 11A) in the nonwoven fabric so as to face the wearer's skin from the viewpoint of preventing the occurrence of wetback. That is, this nonwoven fabric is suitably used as a top sheet for absorbent articles.

  In general, an absorbent article includes a liquid-permeable top sheet, a liquid-retaining absorbent body, and a liquid-impermeable or hardly-permeable back sheet. As the absorbent body, a mixed fiber of flap pulp and a water absorbent polymer, or an absorbent sheet in which a water absorbent polymer is interposed between a pair of pulp sheets can be used. As the back sheet, a synthetic resin film, a film imparted with moisture permeability, a liquid-impermeable nonwoven fabric, and the like can be used. The absorbent article may further include various members according to specific uses of the absorbent article. Such members are known to those skilled in the art. For example, when applying an absorbent article to a disposable diaper or a sanitary napkin, a pair or two or more pairs of three-dimensional guards can be disposed on the left and right sides of the topsheet.

  The nonwoven fabric of the present invention can be used as a sub-layer sheet for absorbent articles in addition to the above-described top sheet for absorbent articles, utilizing the hydrophilic gradient generated after the liquid is passed through. The sublayer sheet is a liquid-permeable sheet that is generally disposed between the surface sheet of the absorbent article and the absorbent body.

  As mentioned above, although this invention was demonstrated based on the preferable embodiment, this invention is not restrict | limited to the said embodiment. For example, in the embodiment shown in FIGS. 1 to 4, the nonwoven fabric 10 has a two-layer structure of a first nonwoven fabric layer 11 and a second nonwoven fabric layer 12, but instead, the outer surface of the second nonwoven fabric layer 12. Furthermore, you may laminate | stack another nonwoven fabric layer 1 layer or 2 layers or more. The same applies to the embodiment shown in FIG. 5, and one or more other nonwoven fabric layers may be laminated on the outer surface of the second region 12 </ b> A.

This invention discloses the following nonwoven fabrics and absorbent articles further regarding embodiment mentioned above.
<1>
When 90 g of artificial urine is passed at a rate of 5.0 g / sec under no-pressure condition, the first region and the second region having different hydrophilicity of the constituent fibers are generated along the thickness direction. Non-woven fabric,
The first region is a region including the surface of the nonwoven fabric, the second region is a region adjacent to the first region when viewed along the thickness direction of the nonwoven fabric,
A nonwoven fabric in which the contact angle of the constituent fibers in the first region is larger than the contact angle of the constituent fibers in the second region when the hydrophilicity is represented by a contact angle with water.

<2>
A fiber treatment agent is applied to each of the constituent fibers of the first region and the second region,
When two or more types of main components are present in the fiber treatment agent, the main component is different between the first region and the second region regardless of which main component is <1. > Non-woven fabric.
<3>
A fiber treatment agent is applied to each of the constituent fibers of the first region and the second region,
<1> or <2> in which the main component of the fiber treatment agent applied to the constituent fibers in the first region is different from the main component of the fiber treatment agent applied to the constituent fibers in the second region. The nonwoven fabric described in 1.
<4>
A fiber treatment agent is applied to each of the constituent fibers of the first region and the second region,
The nonwoven fabric according to any one of <1> to <3>, wherein a main component of the fiber treatment agent applied to the constituent fibers in the second region is a polyorganosiloxane having a hydrophilic group.
<5>
The hydrophilic group is a hydroxyl group, polyoxyalkylene group, amino group, diamino group, polyglyceryl group, epoxy group, carbinol group, carboxyl group, diol group or methacryl group, or a combination of two or more thereof. The nonwoven fabric as described in said <4>.
<6>
The nonwoven fabric according to <4> or <5>, wherein the hydrophilic group is a polyoxyalkylene group or a polyglyceryl group.

<7>
A fiber treatment agent is applied to each of the constituent fibers of the first region and the second region,
The nonwoven fabric according to any one of <1> to <6>, wherein one of main components of the fiber treatment agent applied to the second region is polyoxyalkylene-modified silicone.
<8>
The proportion of the polyoxyalkylene-modified silicone contained in the fiber treatment agent applied to the constituent fibers in the second region is preferably 15% by mass or more, more preferably 20% by mass or more, and 25% by mass or more. The nonwoven fabric according to the above <7>, more preferably 60% by mass or less, further preferably 50% by mass or less, and further preferably 40% by mass or less.
<9>
The number of repeating oxyalkylene groups in the polyoxyalkylene group is preferably 3 or more, more preferably 5 or more, more preferably 7 or more, and preferably 40 or less, more preferably 30 or less, more preferably 20 or less. The nonwoven fabric as described in <8>.
<10>
A fiber treatment agent is applied to each of the constituent fibers of the first region and the second region,
The main component of the fiber treatment agent applied to the first region is hydrocarbon oil, fluorine oil, fatty acid ester, polyoxyalkylene-modified silicone, polyorganosiloxane, and nonionic having an alkyl group having 16 or more carbon atoms. And at least one selected from the group consisting of ionic surfactants, and among these substances, in particular, polyoxyalkylene-modified silicone, polyorganosiloxane, non-alkyl having 16 or more carbon atoms. More preferably, at least one selected from the group consisting of ionic and ionic surfactants is used, and selected from the group consisting of polyorganosiloxanes, nonionic and ionic surfactants having an alkyl group having 16 or more carbon atoms. It is more preferable to use at least one selected from the above <1> to <9 Nonwoven fabric according to any one of the.
<11>
It consists of a laminated structure including a first nonwoven fabric layer and a second nonwoven fabric layer,
The nonwoven fabric according to any one of <1> to <10>, wherein the first nonwoven fabric layer is a region corresponding to the first region, and the second nonwoven fabric layer is a region corresponding to the second region.

<12>
The contact angle of the constituent fibers themselves of the first region is preferably 80 degrees or more after passage of artificial urine, more preferably 85 degrees or more, more preferably 90 degrees or more, and 100 degrees or less. The nonwoven fabric according to any one of <1> to <11>, which is preferably 97 degrees or less, more preferably 94 degrees or less.
<13>
The contact angle of the constituent fibers of the second region itself is preferably 65 degrees or more after passage of artificial urine, more preferably 70, provided that the contact angle of the constituent fibers of the first region is smaller than the contact angle of the constituent fibers of the first region. Any one of <1> to <12> above, more preferably 75 degrees or more, preferably 90 degrees or less, more preferably 87 degrees or less, and still more preferably 84 degrees or less. The nonwoven fabric described.
<14>
After the passage of artificial urine, the difference between the contact angle of the constituent fibers in the first region and the contact angle of the constituent fibers in the second region (the former-the latter) is preferably greater than 0 degree, more preferably 3 More preferably, it is 5 degrees or more, more preferably 5 degrees or more and preferably 30 degrees or less, more preferably 25 degrees or less, and still more preferably 20 degrees or less, according to any one of the above items <1> to <13> Non-woven fabric.
<15>
The contact angle of the constituent fibers in the first region is preferably 75 ° or more, more preferably 78 ° or more, more preferably 81 ° or more, and less than 90 ° before the artificial urine is passed through. Preferably, it is 87 degrees or less, More preferably, it is 84 degrees or less, The nonwoven fabric as described in any one of said <1> thru | or <14>.
<16>
The contact angle of the constituent fibers in the second region is preferably 60 degrees or more, more preferably 65 degrees or more before the artificial urine is passed, on condition that the contact angle of the constituent fibers in the first region is smaller than that. More preferably, it is 70 degrees or more, preferably 85 degrees or less, more preferably 80 degrees or less, and still more preferably 75 degrees or less, according to any one of the above <1> to <15> Non-woven fabric.

<17>
Before the passage of artificial urine, the difference between the contact angle of the constituent fibers in the first region and the contact angle of the constituent fibers in the second region (the former-the latter) is preferably greater than 0 degrees, more preferably 3 <1> to <16>, preferably at least 5 degrees, more preferably at least 5 degrees, and preferably at most 30 degrees, more preferably at most 25 degrees, and even more preferably at most 20 degrees. Non-woven fabric.
<18>
In the state before the passage of artificial urine, the contact angle of the constituent fibers of the first region is less than 90 degrees,
The nonwoven fabric according to any one of <1> to <17>, wherein the contact angle of the constituent fibers in the first region is 90 degrees or more in a state after passing the artificial urine.
<19>
The state according to any one of <1> to <18>, wherein the contact angle of the constituent fibers in the first region is larger than the contact angle of the constituent fibers in the second region in the state before the artificial urine is passed through. Non-woven fabric.
<20>
The nonwoven fabric according to any one of <1> to <19>, wherein the surface of the first region has an uneven structure.
<21>
It consists of a laminated structure including a first nonwoven fabric layer corresponding to the first region and a second nonwoven fabric layer corresponding to the second region,
The first nonwoven fabric layer and the second nonwoven fabric layer are partially joined to form a plurality of joined portions, and the first nonwoven fabric layer protrudes in a direction away from the second nonwoven fabric layer at a portion other than the joined portions. Forming a plurality of convex portions,
The nonwoven fabric according to <20>, wherein a space defined by the first nonwoven fabric layer and the second nonwoven fabric layer is formed inside the convex portion.

<22>
A fiber treatment agent is applied to each of the constituent fibers of the first region and the second region,
One of the main components of the fiber treatment agent applied to the second region is polyoxyalkylene-modified silicone,
In addition to polyoxyalkylene-modified silicone, the substance used as the main component is alkali metal salt of alkyl phosphate ester, polyoxyethylene polyhydric alcohol fatty acid ester, alkyl betaine, alkyl sulfonic acid, alkyl sulfuric acid, dialkyl sulfonic acid or polyoxy The nonwoven fabric according to any one of <1> to <21>, which is ethylene alkylamide.
<23>
An absorbent article comprising the nonwoven fabric according to any one of <1> to <22>, wherein a first region of the nonwoven fabric is disposed so as to face the wearer's skin.
<24>
The absorbent article according to <23>, wherein the nonwoven fabric is used as a surface sheet, and the first region of the nonwoven fabric is arranged to face the wearer's skin.
<25>
The method for producing a nonwoven fabric according to any one of <1> to <22>,
The first fiber treatment agent is applied from one surface of the raw nonwoven fabric, and the second fiber treatment agent having a composition different from that of the first fiber treatment agent is applied from the other surface,
The manufacturing method of the nonwoven fabric from which a 1st fiber treatment agent and a 2nd fiber treatment agent differ in a main component.
<26>
The method for producing a nonwoven fabric according to any one of <1> to <22>,
Laminating a first web made of fibers to which a first fiber treatment agent has been applied and a second web made of fibers to which a second fiber treatment agent having a composition different from that of the first fiber treatment agent has been applied, Having a process of making a nonwoven fabric,
The manufacturing method of the nonwoven fabric from which a 1st fiber treatment agent and a 2nd fiber treatment agent differ in a main component.
<27>
The method for producing a nonwoven fabric according to any one of <1> to <22>,
The first fiber treatment agent is applied to the first web, the second fiber treatment agent having a composition different from that of the first fiber treatment agent is applied to the second web, then both the webs are laminated, and then the laminated web is made into a non-woven fabric. And having a process of
The manufacturing method of the nonwoven fabric from which a 1st fiber treatment agent and a 2nd fiber treatment agent differ in a main component.

<28>
The first fiber treatment agent and the second fiber treatment agent have different main components. Among the first region and the second region adjacent to each other in the thickness direction of the nonwoven fabric, the first fiber treatment agent is added to the first region. The manufacturing method according to any one of <25> to <27>, wherein the second fiber treatment agent is applied to the region.
<29>
The method according to any one of <25> to <28>, wherein one of the main components of the second fiber treatment agent is polyoxyalkylene-modified silicone.
<30>
The proportion of the polyoxyalkylene-modified silicone contained in the second fiber treatment agent is preferably 15% by mass or more, more preferably 20% by mass or more, still more preferably 25% by mass or more, The production method according to <29>, preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less.
<31>
The main components of the first fiber treatment agent are hydrocarbon oil, fluorine oil, fatty acid ester, polyoxyalkylene-modified silicone, polyorganosiloxane, and nonionic and ionic surfactants having an alkyl group having 16 or more carbon atoms. Preferably, it is at least one selected from the group consisting of, among these substances, polyoxyalkylene-modified silicone, polyorganosiloxane, nonionic and ionic surfactants having an alkyl group having 16 or more carbon atoms It is more preferable to use at least one selected from the group consisting of polyorganosiloxane, at least one selected from the group consisting of nonionic and ionic surfactants having an alkyl group having 16 or more carbon atoms. More preferably, any one of the above <25> to <30> The method of production.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, “%” means “mass%”.

[Example 1]
A nonwoven fabric 10 having the structure shown in FIGS. 1 and 2 (a) was produced according to the method described in JP-A No. 2004-174234. The first nonwoven fabric layer 11 uses two types of constituent fibers (one is called “fiber 1” and the other is called “fiber 2”), and the second nonwoven fabric layer 12 uses one type of constituent fiber. Each of the first fiber and the second fiber is a core-sheath fiber in which the core is polyethylene terephthalate (PET) and the sheath is polyethylene (PE). The fineness of the fiber 1 is 2.2 dtex and the fineness of the fiber 2 is 4.4 dtex. Met. The constituent fibers used for the second nonwoven fabric layer 12 were core-sheath fibers having a core of polyethylene terephthalate (PET) and a sheath of polyethylene (PE), and the fineness was 2.2 dtex. Both the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12 had a basis weight of 18 g / m ² . The composition ratio of these fibers and the fiber treating agent used for these fibers are as shown in Table 1. Each of the nonwoven fabric layers 11 and 12 was composed of an air-through nonwoven fabric. In order to produce the respective nonwoven fabric layers 11 and 12 before lamination, first, about 12 g of fibers weighed were immersed in the fiber treatment agent shown in Table 1, and the fiber treatment agent was applied to the fibers. The adhesion amount of the fiber treatment agent was 0.40% with respect to the whole nonwoven fabric. Next, the fibers were carded to form a web, and the web was air-through treated to obtain nonwoven fabrics 11 and 12. Thereafter, the nonwoven fabrics 11 and 12 were laminated, and the nonwoven fabric 11 was sucked into a convex shape with a roll having a suction function, and the nonwoven fabrics 11 and 12 were heat-sealed at the joint portion 13 to form an uneven structure. . Thus, the target nonwoven fabric 10 was obtained.

[Examples 2 to 8 and Comparative Examples 1 to 4]
In Example 1, what is shown in Table 1 was used as the fiber treatment agent applied to the first nonwoven fabric layer 11 and the second nonwoven fabric layer 12. Except this, it carried out similarly to Example 1, and obtained the nonwoven fabric 10 of the structure shown to FIG.1 and FIG.2 (a).
In Comparative Examples 3 and 4, disposable diapers marketed in October 2013, Moony (registered trademark) Airfit (trade name) S size, manufactured by Unicharm Corporation, and Daio Paper Co., Ltd. GON (registered trademark) first underwear (trade name) S size surface sheet was used as it was.
The details of the fiber treatment agents shown in Tables 1 and 2 below are as follows.
・ Lauryl phosphate potassium salt: Neutralized potassium hydroxide of “Fuosfanol ML-200” manufactured by Toho Chemical Co., Ltd. ・ Stearyl phosphate potassium salt: Neutralized potassium hydroxide of “Gripper 4131” manufactured by Kao Corporation -Dimethyl silicone: Shin-Etsu Chemical Co., Ltd., "KM-903"
POE (addition mole number 3) lauryl phosphate potassium salt: “Amholex MP-2K” manufactured by Miyoshi Oil & Fats Co., Ltd.
-POE, POP modified silicone: “X-22-4515” manufactured by Shin-Etsu Chemical Co., Ltd.
POE (addition mole number 1) stearylamide: “Amizole SDE” manufactured by Kawaken Fine Chemicals
Stearyl betaine: “Amphitor 86B” manufactured by Kao Corporation
・ Dioctylsulfosuccinic acid: manufactured by Kao Corporation, “Perex OT-P”

[Evaluation]
For the nonwoven fabrics obtained in the examples and comparative examples (diapers in comparative examples 2 and 3), the first nonwoven fabric layer 11 and the first nonwoven fabric layer 11 before passing artificial urine and after passing artificial urine by the above-described method. 2 The contact angle of the constituent fibers of the nonwoven fabric layer 12 was measured by the method described above. The measurement was performed at the position of the top of the convex portion 14 for the first nonwoven fabric layer 11 and at the position of the concave portion for the second nonwoven fabric layer 12. The results are shown in Tables 1 and 2.
Moreover, about the comparative example 3, the top part of the uneven structure extended continuously in the longitudinal direction of the surface sheet of a diaper was applied to the 1st nonwoven fabric layer 11, and the bottom part was evaluated to the bottom part of the 2nd nonwoven fabric layer 12, and evaluation was implemented. When evaluating the contact angle after passing through the liquid, after passing a predetermined amount of liquid, spray cold spray to solidify the hot melt and weaken the adhesive force so that it does not reach the liquid passing part. The sheet was peeled off and the contact angle after liquid passage was evaluated. Further, Comparative Example 4 was evaluated by applying the top of the uneven structure of the top sheet of the diaper to the first nonwoven fabric layer 11 and the bottom of the nonwoven fabric existing further below the second nonwoven fabric layer 12. The contact angle after liquid passing was evaluated in the same manner as in Comparative Example 3.

  Moreover, the absorbent article which used the nonwoven fabric obtained by the Example and the comparative example as a surface sheet was manufactured, and the wet-back amount was measured with the following method. The amount of wetback was measured separately for the surface sheet and the absorber. The results are also shown in Tables 1 and 2.

[Measurement of wetback]
Cold spray was sprayed on Mary's (registered trademark) tape (S size), which is a disposable diaper manufactured by Kao Corporation, which was commercially available in October 2013 to solidify the adhesive, and the top sheet was removed. Instead of the removed surface sheet, the nonwoven fabrics obtained in the examples and comparative examples were reapplied to produce an absorbent article to be measured. However, in Comparative Examples 2 and 3, this operation was not performed, and the diaper itself was subjected to wetback measurement. The absorbent article to be measured was spread in a flat shape and placed horizontally such that the skin facing surface side (surface sheet side) faced up. Under this condition, 30 g of artificial urine was injected three times at a flow rate of 5 g / second (total 90 g injection). After the first injection, the second injection was performed 10 minutes later. The place where the artificial urine was injected was the central portion in the horizontal direction at a position spaced 130 mm inward in the vertical direction from the end on the ventral side in the vertical direction (longitudinal direction) of the absorber. After the artificial urine was injected into the absorbent article for the second time, this was left for 10 minutes, and then a collagen film (Coffi J, manufactured by Viscofan) was cut into 7 cm squares, and 4 sheets were stacked. Was placed on the artificial urine injection site in FIG. 1, and 7 kPa was applied from above the collagen film for 1 minute. As a result, the artificial urine absorbed and retained in the absorbent article was absorbed into the collagen film. Then, the mass of the collagen film which absorbed artificial urine was measured. The mass of the collagen film before absorption was subtracted from this mass to calculate the mass of artificial urine absorbed by the collagen film. This value was defined as the wetback amount (the sum of the wetback amount derived from the top sheet and the wetback amount derived from the absorber). In the measurement of the amount of wetback derived from the topsheet, after the third artificial urine was injected and left for 10 minutes, only the topsheet was peeled off, and an OHP film (VF1300 manufactured by KOKUYO) was interposed between the absorber and the topsheet. ) Was sandwiched, and the liquid return amount was measured in the same manner as described above to obtain the wet back amount derived from the top sheet. The amount of wet back derived from the absorber was determined by subtracting the amount of wet back derived from the topsheet from the above liquid return amount.

  As is clear from the results shown in Table 1 and Table 2, when the nonwoven fabric obtained in each example is used as a top sheet for absorbent articles, the amount of wetback may be reduced compared to the nonwoven fabric of the comparative example. I understand. In particular, Comparative Example 2 in which the fiber processing agent having the same main component as the first nonwoven fabric layer is applied to the second nonwoven fabric layer has a contact angle difference of 0 degrees after passing through, and the wetback is greater than any of the examples. It has grown up. As a comparison with Comparative Example 2, Example 8 in which the second nonwoven fabric layer contains 50% of a main component different from the first nonwoven fabric layer has a contact angle difference after passing through larger than 0 degrees, and wetback. Was smaller than Comparative Example 2.

DESCRIPTION OF SYMBOLS 10 Nonwoven fabric 11 1st nonwoven fabric layer 12 2nd nonwoven fabric layer 13 Joint part 14 Convex part 15 Concave part 16 Space

Claims (10)

When 90 g of artificial urine is passed at a rate of 5.0 g / sec under no-pressure condition, the first region and the second region having different hydrophilicity of the constituent fibers are generated along the thickness direction. Non-woven fabric,
The first region is a region including the surface of the nonwoven fabric, the second region is a region adjacent to the first region when viewed along the thickness direction of the nonwoven fabric,
A nonwoven fabric in which the contact angle of the constituent fibers in the first region is larger than the contact angle of the constituent fibers in the second region when the hydrophilicity is represented by a contact angle with water. A fiber treatment agent is applied to each of the constituent fibers of the first region and the second region,
The nonwoven fabric according to claim 1, wherein a main component of the fiber treatment agent applied to the constituent fibers in the first region is different from a main component of the fiber treatment agent applied to the constituent fibers in the second region.   The nonwoven fabric according to claim 2, wherein one of the main components of the fiber treatment agent applied to the second region is polyoxyalkylene-modified silicone.   The nonwoven fabric according to claim 3, wherein the proportion of the polyoxyalkylene-modified silicone contained in the fiber treatment agent is 15% by mass or more.   The main component of the fiber treatment agent applied to the first region is hydrocarbon oil, fluorine oil, fatty acid ester, polyoxyalkylene-modified silicone, polyorganosiloxane, and nonionic having an alkyl group having 16 or more carbon atoms and The nonwoven fabric according to any one of claims 1 to 4, wherein the nonwoven fabric is at least one selected from the group consisting of ionic surfactants. In the state before the passage of the artificial urine, the contact angle of the constituent fibers of the first region is less than 90 degrees,
The nonwoven fabric according to any one of claims 1 to 5, wherein the contact angle of the constituent fibers in the first region is 90 degrees or more in a state after passing the artificial urine.   7. The contact angle of the constituent fibers in the first region is larger than the contact angle of the constituent fibers in the second region in a state before passing the artificial urine. Non-woven fabric.   The nonwoven fabric as described in any one of Claims 1 thru | or 7 which has an uneven structure in the surface of a 1st area | region. It consists of a laminated structure including a first nonwoven fabric layer corresponding to the first region and a second nonwoven fabric layer corresponding to the second region,
The first nonwoven fabric layer and the second nonwoven fabric layer are partially joined to form a plurality of joined portions, and the first nonwoven fabric layer protrudes in a direction away from the second nonwoven fabric layer at a portion other than the joined portions. Forming a plurality of convex portions,
The nonwoven fabric according to claim 8, wherein a space defined by the first nonwoven fabric layer and the second nonwoven fabric layer is formed inside the convex portion.   An absorbent article comprising the nonwoven fabric according to any one of claims 1 to 9, wherein the first region of the nonwoven fabric is disposed so as to face the wearer's skin.

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