JP2005319043A - Surface sheet of absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface sheet of an absorbent article quickly absorbing excreted liquid and swiftly moving it to an absorbent body positioned thereunder. <P>SOLUTION: This surface sheet 1 of the absorbent article is constituted by superposing an upper layer fiber layer 2 abutting on the skin on a lower layer fiber layer 3 abutting on the absorbent body. The hydrophilicity of the upper layer 2 is weaker than that of the lower layer 3, which forms a hydrophilicity gradient in the thickness direction. The lower layer 3 is formed with a plurality of cuts 5 or formed with a plurality of opening parts 7. The skin abutment face side of the upper layer 2 is formed with a plurality of projecting parts 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface sheet of an absorbent article. Moreover, this invention relates to the absorbent article provided with this surface sheet.

  The present applicant has previously proposed a surface sheet of an absorbent article having a hydrophilicity gradient in the thickness direction (see Patent Document 1). By providing the hydrophilicity gradient, there is an advantage that quick absorption of liquid (liquid drawability) is improved, and liquid return of the liquid once absorbed by the absorber is less likely to occur. Further, there is an advantage that the surface of the sheet has a dry and dry feeling.

  However, various performances required for absorbent articles are further increased, and higher performance is also required for permeation and absorption of liquids by the surface sheet.

JP-A-8-246321

  Accordingly, an object of the present invention is to provide a surface sheet of an absorbent article having further improved performance as compared with the above-described conventional surface sheet.

  The present invention is configured by laminating an upper fiber layer that contacts the skin and a lower fiber layer that contacts the absorber, and the hydrophilicity of the upper layer is weaker than the lower layer, thereby having a hydrophilicity gradient in the thickness direction. A top sheet of an absorbent article in which a number of cuts or a number of openings are formed in the lower layer, and a number of protrusions are formed on the skin contact surface side of the upper layer. The object is achieved by providing.

  Moreover, this invention provides the absorbent article provided with the said surface sheet.

  According to the surface sheet of the present invention, since the hydrophilicity gradient is provided from the upper layer to the lower layer, the excreted liquid is quickly absorbed by the sheet and quickly moves to the absorber located below the liquid. Moreover, since the diffusion of the liquid in the plane direction is suppressed in the lower layer, the movement of the liquid to the absorber is further promoted. Furthermore, since many convex parts are formed on the skin contact surface side of the sheet, the contact area between the sheet and the skin is reduced. As a result, the surface of the sheet has a dry and dry feeling, and the liquid once absorbed by the absorbent body is less likely to reverse. Further, since the convex portions are formed, the cushion feeling and the soft feeling of the seat are improved.

  The present invention will be described below based on preferred embodiments with reference to the drawings. FIG. 1 shows an exploded perspective view of an embodiment of the top sheet of the absorbent article of the present invention. FIG. 2 is a cross-sectional view. The topsheet 1 of the present embodiment is composed of a laminate in which two layers of an upper layer 2 that contacts the skin and a lower layer 3 that contacts the absorber are stacked. Each layer is a fiber layer made of a fiber material and has the same size. The upper and lower layers 2 and 3 are integrated by a known integration means, for example, an adhesive, fiber entanglement, heat fusion, or the like.

  The upper surface of the upper layer 2 constitutes the skin contact surface of the top sheet 1. On the other hand, the lower surface of the lower layer 3 constitutes the absorber contact surface of the topsheet 1. A large number of convex portions are formed on the skin contact surface side of the upper layer 2, and the skin contact surface is an uneven surface. On the other hand, the surface of the lower layer 3 is substantially flat. Therefore, the surface sheet 1 composed of both layers 2 and 3 has a skin contact surface that is an uneven surface and an absorber contact surface that is substantially flat. The term “substantially flat” means that the surface is uniformly flat when viewed macroscopically, and the surface of the fiber layer is not only flat but also slightly formed by embossing or the like. This also includes a fiber layer having a depressed embossed portion.

  The upper layer 2 and the lower layer 3 are both hydrophilic. There is a difference in hydrophilicity between the upper layer 2 and the lower layer 3, and the upper layer 2 is less hydrophilic than the lower layer 3. Thereby, the surface sheet 1 has a hydrophilicity gradient in which the hydrophilicity is increased from the upper layer 2 side toward the lower layer 3 side in the thickness direction. Due to this hydrophilicity gradient, the top sheet 1 has high liquid drawability, and the excreted liquid is quickly absorbed by the top sheet 1 and quickly transferred to the absorber located below it. The hydrophilicity may change continuously or may change stepwise. The degree of hydrophilicity of the upper layer 2 and the lower layer 3 is compared with the initial hydrophilicity (permeation time) by performing a durability hydrophilic test described below for each of the upper layer 2 and the lower layer 3.

  In order to impart hydrophilicity to the upper layer 2 and the lower layer 3, it is only necessary to use hydrophilic fibers inherently as the fibers constituting these layers, or those obtained by hydrophilizing hydrophobic fibers. For the hydrophilic treatment, for example, various surfactants known in the technical field may be used. When using hydrophilic fibers, each of the layers 2 and 3 does not require that all of the constituent fibers are hydrophilic fibers. If the entire layer exhibits hydrophilicity, some of the fibers include hydrophobic fibers. It may be. Similarly, in the case of using a hydrophobized hydrophobic fiber, each of the layers 2 and 3 does not require that all of the constituent fibers are hydrophobized hydrophobic fibers. A part of hydrophobic fibers that have not been applied may be included.

  As the inherently hydrophilic fiber, for example, cellulosic fibers such as rayon, acetate, cotton, and Tencel (registered trademark) can be used. Examples of hydrophobic fibers include polyolefin fibers such as polyethylene and polypropylene, polyester fibers such as polyethylene terephthalate and polypropylene terephthalate, polyamide fibers, acrylic fibers, and a core sheath made of a combination of two or more of these resins. Type composite fiber and side-by-side type composite fiber.

  The fibers constituting the upper layer 2 and the lower layer 3 may be short fibers or continuous filaments depending on the production method of these layers, the performance required for these layers, and the like. Or the form of a tow | toe may be sufficient. About a fiber diameter, a suitable value is selected according to the performance requested | required of the upper layer 2 and the lower layer 3, respectively. In general, the fineness is preferably 1 to 6 dtex, particularly 1.5 to 4 dtex, regardless of whether the upper layer 2 or the lower layer 3 is used.

  It is preferable that the hydrophilicity gradient described above is stably maintained even after the liquid is excreted a plurality of times during use of the absorbent article. Therefore, it is preferable that each of the upper layer 2 and the lower layer 3 has durable hydrophilicity. In the present specification, the term “durable hydrophilic property” means that the durable hydrophilic property in the durable hydrophilic test described below is 2 or more times.

[Durable hydrophilicity test]
As shown in FIG. 3, a 5.5 cm diameter N0.101 filter paper (manufactured by TOYO filter paper) 11 is stacked on the top sheet 1 cut out to 60 mm × 60 mm, and the rubber packings 12 and 12 ′ are stacked from above and below. Then, 40 g of ion-exchanged water is supplied to the upper cylinder 13 under a state of being sandwiched and fixed by a pair of glass cylinders 13 and 13 ′ having a diameter of 35 mm, and the filter paper 11 and the surface sheet are supplied from the start of supplying the ion-exchanged water. 1 until the weight of ion-exchanged water accumulated in the lower cylinder 13 ′ passing through 1 reaches 20 g (this time is referred to as permeation time), and this permeation time is determined as the initial hydrophilicity of the topsheet 1. To do. The cylinders 13 and 13 'are cylindrical with a height of 75 mm, an inner diameter of 35 mm, and a wall thickness of 3 mm, and flange portions having an outer diameter of 60 mm are provided at both ends thereof. Below the lower cylinder 13 ′, an electronic balance 15 on which a liquid receiver 14 is placed is arranged. The initial hydrophilicity means that the initial hydrophilicity of the topsheet 1 is higher as the permeation time is shorter. If the permeation time is 180 seconds or less, the top sheet 1 is taken out and the ion-exchanged water contained therein is dried and removed, and then the same measurement is repeated. When drying and removing ion-exchanged water, an operation of absorbing ion-exchanged water using an absorbent paper (for example, kitchen paper) may be used in combination. When the number of measurements when the permeation time exceeds 1880 seconds is n, (n-1) times of measurement is regarded as the durable hydrophilic property of the topsheet 1. It means that durable hydrophilicity is so high that the frequency | count of measurement is large.

  In order for each of the upper layer 2 and the lower layer 3 to have durable hydrophilic properties, for example, fibers that are inherently hydrophilic are mainly used as the fibers constituting these layers, or hydrophobic fibers that have been subjected to durable hydrophilic treatment are used. Use it.

  When the fibers constituting the upper layer 2 are hydrophobic fibers, examples of the hydrophobic fibers include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, vinyl resins such as polyvinyl chloride, and nylon. A polyamide-based resin or the like is used. Moreover, the composite fiber (a core-sheath type composite fiber or a side-by-side type composite fiber) made of a combination of two kinds of resins among the above-mentioned various raw materials can also be used. Among these, particularly preferable fibers are polyester-based resins such as polypropylene (polyolefin resin) and polyethylene terephthalate, and core-sheath type composite fibers using polypropylene or polyester as the core component and polyethylene as the sheath component.

  When the fiber constituting the upper layer 2 is a hydrophobic fiber, the hydrophilic oil used for the durable hydrophilic treatment of the hydrophobic fiber includes various anionic, cationic, amphoteric and nonionic surfactants. Those having a molecular weight can be used alone or in combination. Among these, it is preferable to add a large amount of a nonionic surfactant from the viewpoint of adhesion stability to the fiber surface and a decrease in function due to pseudo-bonding between the surfactant molecules, and those having a high molecular weight are particularly durable. It is more preferable from the point of obtaining. In addition, as a means for facilitating the fixing of the hydrophilic oil agent to the fiber surface, it is preferable to use a means such as a fixing agent or kneading from the viewpoint of enhancing durability. The content of the upper layer 2 of the hydrophobic fiber hydrophilized with the hydrophilic oil agent is preferably 50 to 100%, particularly 80 to 100%, based on the total mass of the upper layer 2. Further, the adhesion amount of the hydrophilic oil agent is 0.2 to 1.0% by mass of the hydrophobic fiber, from the viewpoint of stably expressing hydrophilicity on the fiber surface and preventing a decrease in texture such as stickiness. preferable.

  When the fibers constituting the lower layer 3 are hydrophobic fibers, the same fibers as the hydrophobic fibers used for the upper layer 2 can be used as the hydrophobic fibers. Particularly preferred fibers are core-sheath type composite fibers and side-by-side type composite fibers.

  When the fiber constituting the lower layer 3 is a hydrophobic fiber, the hydrophilic oil agent used for durable hydrophilization treatment of the hydrophobic fiber includes various anionic, cationic, amphoteric and nonionic surfactants. Those having a large molecular weight can be used alone or in combination. Among these, it is preferable to add a large amount of a cationic surfactant in terms of high initial hydrophilicity and moderate durability. The content of the lower layer 3 of the hydrophobic fiber hydrophilized with the hydrophilic oil agent is preferably 50 to 100%, particularly 80 to 100%, based on the total mass of the lower layer 3. Moreover, the hydrophilic oil agent adheres to the hydrophobic fibers in an amount of 0.2 to 1.0% by mass to stably express the hydrophilicity on the fiber surface, and the processability decreases (the surface of the absorber is made of the hydrophilic oil agent). It is preferable from the viewpoint of preventing thermal deterioration due to contamination and bonding deterioration due to an adhesive.

  As the upper layer 2 and the lower layer 3, for example, various webs or nonwoven fabrics can be used according to the manufacturing method of the top sheet 1. As the web, for example, a card web obtained by opening a short fiber with a card machine, an airlaid web obtained by depositing a short fiber conveyed in an air stream, and a continuous filament spun by melt spinning are taken up by an ejector. Examples include spunbond webs obtained by deposition. Examples of the nonwoven fabric include air-through nonwoven fabric, spunlace nonwoven fabric, air laid nonwoven fabric, spunbond nonwoven fabric, and melt blown nonwoven fabric.

As described above, a large number of convex portions 4, 4,... Are formed on the skin contact surface side of the upper layer 2. The convex portions 4 are substantially circular in plan view, and are spaced apart from each other and distributed over the entire skin contact surface. It viewed the convex portion 4 has its area of 2 to 100 mm ^2, it is particularly 10 to 80 mm ² around the small protrusions, effectively to separate the top sheet 1 and the skin, that express the dry feeling To preferred. For the same reason, the height H from the skin contact surface is preferably about 0.3 to 5 mm, particularly about 0.5 to 3 mm.

  The convex portions 4 are regularly formed. The density of the protrusions 4 is preferably such that when a circle having a radius of 1 cm is considered, 1 to 20, particularly 2 to 10 are present in the circle.

  In the surface sheet 1 of the present embodiment, a number of cuts (slits) 5, 5,. A plurality of the notches 5 are arranged in the longitudinal direction to form a discontinuous straight line, and the straight lines are arranged in multiple rows. Each notch 5 is arranged so that when any one of the notches 5 is noted, an arbitrary line perpendicular to the notch 5 is drawn, the line always intersects with the other notch 5. Has been.

  The reason why the cut 5 is formed in the lower layer 3 is as follows. As described above, the lower layer 3 has a higher hydrophilicity than the upper layer 2 and can easily draw liquid. However, at the same time, the lower layer 3 also has the property of easily diffusing the liquid in the plane direction. If the liquid diffuses in the plane direction, the rapid transition of the liquid from the top sheet 1 to the absorber is prevented. Therefore, in the surface sheet 1 of the present embodiment, by forming a large number of cuts 5 in the lower layer 3, it is difficult for the liquid to diffuse in the planar direction in the lower layer 3, and the liquid is quickly moved in the thickness direction of the lower layer 3. So that it is transparent.

  The absorption and transmission mechanism of the liquid in the surface sheet 1 of this embodiment is schematically shown in FIG. The liquid excreted on the skin contact surface of the top sheet 1 is absorbed and transmitted to the upper layer 2 and moves to the lower layer 3. Since the hydrophilicity gradient is formed from the upper layer 2 to the lower layer 3, the liquid is rapidly transferred from the upper layer 2 to the lower layer 3. The liquid that has migrated to the lower layer 3 passes through this and migrates to the absorber 6, and part of it diffuses in the plane direction. The liquid diffused in the plane direction is prevented from further diffusion by the cut 5. As a result, the liquid moves preferentially in the thickness direction of the sheet, and the transfer of the liquid from the lower layer 3 to the absorber 6 is promoted. As is clear from this explanation, the notch 5 acts as a liquid dividing mechanism that prevents the liquid from diffusing in the plane direction in the lower layer 3.

  The cut 5 is not particularly limited as long as it has a length that can prevent the liquid from diffusing in the plane direction. In general, the length of each notch 5 is preferably 3 to 30 mm, particularly 5 to 20 mm, from the viewpoint of sufficiently preventing the liquid from diffusing in the plane direction in the lower layer 3.

  There is no restriction | limiting in particular in the formation method of the notch 5, A means well-known in the said technical field, for example, a rotary die cutter etc., can be used.

  In order to manufacture the topsheet 1 of the present embodiment, for example, the lower layer 3 made of a web or a nonwoven fabric is formed according to a known method, and the cut 5 is formed thereon by the above-described method. It is preferable that the lower layer 3 contains latent crimpable fibers that are in a state before crimps are developed, because it is easy to form the convex portions 4 in the upper layer 2. Apart from the lower layer 3, the upper layer 2 made of a web or a nonwoven fabric is formed according to a known method. Then, the lower layer 3 and the upper layer 2 are overlapped, and both are integrated by a known integration means. Examples of the integration means include bonding with an adhesive, bonding by heat sealing, and entanglement of constituent fibers. By heating the sheet after the integration, the latent crimpable fibers contained in the lower layer 3 are thermally contracted to develop crimps. Thereby, the lower layer 3 is contracted in the plane direction. On the other hand, since the upper layer 2 does not shrink, the upper layer 2 rises in the thickness direction by an amount corresponding to the shrinkage of the lower layer 3. Thus, a large number of convex portions 4 are formed on the upper layer 2. Details of the formation of the convex portion by such a method are disclosed in Japanese Patent Application Laid-Open Nos. 2002-187228, 2003-126147, 2003-247155, and 2003 related to the earlier application of the present applicant. -250836 and the like.

The surface sheet 1 thus produced preferably has a basis weight of 20 to 100 g / m ² , particularly 30 to 80 g / m ² in consideration of various properties required for the absorbent article. For the top layer ^2, 10~30g / m 2, preferably in particular 10 to 25 g / m ^2, with respect to the lower layer 3, 10~30g / m ^2, it is particularly preferably 10 to 25 g / m ^2.

As a specific example of the surface sheet 1 of the present embodiment, as the lower layer 3, a non-woven fabric obtained by a card method having a basis weight of 20 g / m ^{2 made} of a composite fiber of polyethylene and polypropylene having a fineness of 2.2 dtex is used. Using a nonwoven fabric obtained by a card method having a basis weight of 20 g / m ^{2 made} of a composite fiber of polyethylene and polyethylene terephthalate having a fineness of 2.2 dtex, both are partially joined by embossing, and an integrated fiber sheet is mentioned. It is done. The area of the projections 4 in the upper layer 2 in plan view is 4 mm ² , the height is 1.5 mm, and the number of projections 4 present in a circle with a radius of 1 cm is 5.

  When incorporating the topsheet 1 of this embodiment into an absorbent article, it is preferable that the hydrophilicity of the absorbent body is higher than the hydrophilicity of the lower layer 3 in the topsheet 1. Accordingly, the hydrophilicity is sequentially increased in the order of the upper layer 2, the lower layer 3, and the absorbent body, and the drawability of the liquid excreted in the top sheet 1 is further improved. The level of hydrophilicity of the upper layer 2 and the lower layer 3 before liquid permeation is preferably the level of hydrophilicity of the constituent fibers, and can be determined using the contact angle of ion-exchanged water with respect to the constituent fibers as an index. That is, the contact angle is an angle between the water droplet on the fiber and the fiber surface, and it can be determined that the smaller the contact angle, the higher the hydrophilicity. If the contact angle difference is within ± 3 °, it is determined that the contact angles are substantially the same and the hydrophilicity is substantially equal.

  The degree of hydrophilicity of the upper layer 2 and the lower layer 3 after liquid permeation is preferably the degree of hydrophilicity of the constituent fibers, and can be determined using the contact angle of ion-exchanged water with respect to the constituent fibers after liquid permeation as an index. Specifically, the contact angle of ion-exchanged water with respect to the constituent fibers after 10 g of ion-exchanged water has been permeated through a circle having a diameter of 10 mm five times (after liquid permeation) can be determined as an index. That is, it can be determined that the smaller the contact angle, the higher the hydrophilicity.

  From the standpoint that the liquid permeability is stably maintained during use, and the surface flow of the liquid and wetback can be prevented stably for a long time during use, the fibers constituting the upper layer 2 are made of ion-exchanged water before liquid permeation. Ion exchange water having a contact angle of 30 ° to 80 °, particularly 40 ° to 70 °, and having a total of 50 g or 100 g of ion exchange water permeated in a circle having a diameter of 10 mm and drying at 30 ° C. for 2 hours. The contact angle is preferably from 35 ° to 80 °, particularly preferably from 45 ° to 75 °. From the same viewpoint, the fiber constituting the lower layer 3 has a contact angle of ion exchange water before liquid permeation of 60 ° or less, particularly 40 ° or less, and allows a total of 50 g of ion exchange water to pass through a circle having a diameter of 10 mm. The contact angle of ion-exchanged water after drying at 30 ° C. for 2 hours is preferably 30 ° to 70 °, particularly preferably 30 ° to 60 °. As described above, the contact angle after the liquid permeation is evaluated after passing 10 g of ion-exchanged water through a circle with a diameter of 10 mm five times. However, 10 g of ion-exchanged water is within a circle with a diameter of 10 mm. It is preferable that the upper layer 2 and the lower layer 3 have the above-mentioned adhesion angle even after 10 times are transmitted. The method for measuring the contact angle of ion-exchanged water is as follows.

(1) Measuring method of contact angle (initial contact angle) of ion-exchanged water with constituent fibers Use a KEYENCE microscope VH-8000 with a medium magnification zoom lens (with illumination ring) tilted to 90 °, 500 times The measurement was performed under the conditions of The measurement environment was 20 ° C./50% RH, and the measurement sample was set so that it could be observed from the CD direction of the web (nonwoven fabric). The reason for observing the web from the CD direction is that the fibers of the web are generally oriented in the MD direction, and the possibility that the fibers are arranged in the width direction of the measurement screen increases. By setting in this way, the lens is observed from a direction perpendicular to the fiber length direction. As the measurement sample, a top sheet was cut into a size of MD 150 mm × CD 70 mm with the upper and lower layers integrated. When determining the contact angle of the upper constituent fibers, use the fibers on the upper layer surface as the measurement target, and when determining the contact angles of the lower constituent fibers, measure the fibers on the lower layer surface (the surface that contacts the absorber). And Usually, in a fiber sheet having a multilayer structure, it is possible to divide the sheet at the interface, but depending on the condition of the interface, fibers in another layer may be mixed. For this reason, when it is necessary to measure the upper and lower layers separately for some reason, the contact angle is measured on a non-weighted surface. Next, a sheet cut with the measurement surface facing upward is set on the measurement stage, and water droplets are attached to the fiber surface with a spray bottle filled with ion-exchanged water (using a tool that makes the fog state as fine as possible). The image is captured within 5 seconds (2 to 3 seconds as much as possible). The reason why it is necessary to capture an image in a short time after attachment is to prevent the attached water droplet from evaporating due to the light emitted from the measurement part of the microscope and to prevent contact angle change due to the oil agent. The contact angle of 10 observation results in a state where the focal point of both ends or one end of the water droplet was clear was measured, and the average value thereof was defined as “contact angle”. As shown in FIG. 8, the contact angle is measured by drawing a tangent line to the fiber of the water droplet and image analysis or a protractor. The contact angle can be measured by taking out each constituent fiber from the upper and lower layers instead of the surface sheet.

In addition, it is necessary to pay attention to the following items (A) to (C) when measuring the contact angle.
(A) The contact angle on the upper surface of the fiber is measured. The measurement is not performed on water droplets that fall on the bottom of the fiber, or on two or more fibers.
(B) When the fiber has a fine crimp such as a spiral shape, it is measured at a place where the crimp is small or the fiber is stretched to eliminate the crimped state.
(C) The measurement result of the contact angle is an arithmetic average of 10 measurement values at different locations. However, if the hydrophilicity is high, water droplets are unlikely to stay on the fibers during measurement and may flow. In this case, the “contact angle” is determined according to the flow rate.
-If less than 40% of the total number of measurements flows before the measurement value reaches 10, the average result of the 10 measurement values is defined as the "contact angle".
・ If 40% or more of the total number of measurements has flowed up to 10 measurement values, or if 10% of measurements have been taken and 40% or more have flown, the “contact angle” is 20 °. The following.

(2) Measuring method of contact angle of ion-exchanged water with respect to constituent fibers after liquid permeation (contact angle after liquid permeation) Measurement of contact angle before liquid permeation described above, except for preparing a measurement sample as follows. Measure as in the method.

[Preparation of measurement sample]
10 pieces of paper (paper made of pulp having a basis weight of 30 g / m ² and having a crepe rate of 5 to 10%) obtained by cutting the surface sheet into a size of 150 mm × 70 mm and adjusting this to the same size as the surface sheet The acrylic plate with a cylinder shown in FIG. 5 was placed thereon, overlaid on a horizontal surface. A weight was placed on the acrylic plate so that a load of 10 g / cm ² was applied to the top sheet. The dimensions of the acrylic plate are 200 mm long x 100 mm wide x 8 mm thick, the height of the cylinder from the top of the acrylic board is 50 mm, the inner diameter of the cylinder is 22 mm from the top end of the cylinder to 40 mm, and downward from the large diameter part. In the range up to 5 mm, the inner diameter gradually decreased, and the small diameter portion (height 5 mm) up to the lower end of the cylinder was 10 mm. The acrylic plate was also provided with a coaxial hole having an inner diameter of 10 mm. The large diameter part and the small diameter part were placed. In some cases, the inner surface of the cylinder while marking the periphery of the injection portion in advance had a linear cross-sectional shape on the left and right sides of the cylinder axis. In the acrylic plate, the hole provided in the acrylic plate can be positioned at the center of the topsheet. When marking in advance, use marking means that does not affect the diffusion of the liquid, or place a mark indicating the center of the MD / CD on the measurement sample and the end of the acrylic plate, and measure at the center intersection. To do.

Under this condition, ion-exchanged water is put into a 10 mL beaker and gently poured into the cylinder for 3 to 5 seconds. From the viewpoint of easy observation, the ion exchange water used is colored with 0.3% Red No. 2 (external addition). The injection amount was 10 g, and the entire amount was injected. After the injection was completed and the ion exchange water disappeared from the surface sheet surface, it was left for 30 seconds, and then 10 sheets of paper were replaced with new ones and set again in the same manner. When exchanging the paper, the weight, the acrylic plate, and the top sheet are moved. At this time, the acrylic plate and the top sheet are not separated so that ion exchange water can permeate at the same place. And again, ion-exchanged water was injected in the same manner. If the ion exchange water does not disappear from the surface of the surface sheet (no liquid permeation) even after 180 seconds from the start of the ion exchange water injection, the contact angle is not measured because measurement is impossible.
After repeating such an operation and injecting a total of 50 g (5 times) of ion exchange water, the weight and the acrylic plate were removed, and the surface sheet after removing the paper was DSR-114S (ISUZU) electric dryer. Was dried at 30 ° C. for 2 hours to obtain a sample for measurement of the dried surface sheet. In addition, the measurement of a contact angle is performed about the component fiber of the part (circle) which permeate | transmitted the ion-exchange water of this measurement sample.

  The contact angle of ion exchanged water after allowing 100 g of ion exchanged water to pass through a circle with a diameter of 10 mm and drying at 30 ° C. for 2 hours is 10 times instead of 5 times of injection of 10 g of ion exchanged water. Except for repetition, the measurement can be performed in the same manner as in the method for measuring the contact angle of ion-exchanged water with respect to the constituent fiber after permeation as described above.

  Next, a second embodiment of the present invention will be described with reference to FIGS. For the points that are not particularly described with respect to these embodiments, the description in detail regarding the first embodiment is applied as appropriate. 5 and 6, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals.

  In the topsheet 1 of the second embodiment shown in FIGS. 5 and 6, the upper layer 2 is the same as that of the first embodiment. The lower layer 3 has a large number of circular openings 7 formed in the lower layer 3. The openings 7 are distributed almost uniformly over the entire lower layer 3.

  In the topsheet 1 of the present embodiment, the liquid excreted on the skin contact surface is first absorbed by the upper layer 2, passes through this, and moves to the lower layer 3. The liquid that has migrated to the lower layer 3 permeates this and migrates to the absorber, and part of it diffuses in the planar direction. However, the diffusion of the liquid in the planar direction is restricted at the periphery of the opening 7, and the liquid does not diffuse over a long distance. As a result, the liquid moves preferentially in the thickness direction of the sheet, and the transition of the liquid from the lower layer 3 to the absorber is promoted. As is clear from this explanation, in the present embodiment, by providing a large number of openings 7 in the lower layer 3, the diffusion of the liquid in the plane direction is divided.

The area of each opening 7 is preferably 1 to 50 mm ² , particularly 3 to 30 mm ² , from the viewpoint that the diffusion of the liquid in the plane direction can be effectively divided. For the same reason, in any region of the lower layer 3, the openings 7 are arranged so that there are 1 to 5, in particular, 1 to 3 openings 7 on average in a circle having a radius of 1 cm. Preferably it is. The total area of the openings 7 is 1 to 50%, particularly 5 to 30%, with respect to the apparent area of the lower layer 3, which improves the absorption and permeability of the liquid in the lower layer 3 and diffuses in the plane direction. It is preferable from the viewpoint of balance with prevention.

  The present invention is not limited to the embodiment. For example, in the first embodiment, all of the cuts 5 are directed in one direction, but instead of this, the cuts 5 extending in a certain direction and in a direction perpendicular thereto may be alternately arranged. Further, the lengths of the cuts 5 do not have to be constant, and various lengths of cuts may be appropriately combined.

  In the second embodiment, the opening 6 is circular, but the shape of the opening is not limited to this, and may be a polygon such as a triangle or a quadrangle, or an elongated opening.

  Moreover, in each said embodiment, although the surface sheet was a 2 layer structure, it may replace with this and may have a 3 or more layer structure. When the structure has three or more layers, it is preferable that the hydrophilicity is sequentially increased from the upper layer to the lower layer.

  In the present invention, an embodiment obtained by combining the above-described embodiments may be employed.

It is a disassembled perspective view which shows 1st Embodiment of the surface sheet of the absorbent article of this invention. It is sectional drawing which shows 1st Embodiment of the surface sheet of the absorbent article of this invention. It is a schematic diagram which shows the durable hydrophilic property measuring method. It is a schematic diagram which shows the absorption-and-transmission mechanism of the liquid in the surface sheet of 1st Embodiment. It is a disassembled perspective view (figure 1 equivalent figure) which shows 2nd Embodiment of the surface sheet of the absorbent article of this invention. It is sectional drawing (FIG. 2 equivalent view) which shows 2nd Embodiment of the surface sheet of the absorbent article of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Top sheet 2 Upper layer 3 Lower layer 4 Convex part 5 Cut 6 Absorber 7 Opening part

Claims (5)

  The upper fiber layer that contacts the skin and the lower fiber layer that contacts the absorber are laminated, and the hydrophilicity of the upper layer is weaker than that of the lower layer, thereby having a hydrophilicity gradient in the thickness direction. When comparing the upper and lower surface layer portions, the lower layer liquid absorption area is smaller than the upper layer liquid absorption area, and the lower layer has a large number of cuts or a large number of openings, and further the upper layer A top sheet of an absorbent article in which a large number of convex portions are formed on the skin contact surface side.   2. The top sheet of an absorbent article according to claim 1, wherein the convex portions have a substantially circular shape in a plan view and are dispersedly arranged over the entire area of the skin contact surface apart from each other.   The top sheet of an absorbent article according to claim 1 or 2, wherein each of the upper and lower layers has durable hydrophilicity.   An absorbent article using the sheet according to claim 1 as a top sheet of the absorbent article. The absorbent article according to claim 4, wherein the hydrophilicity of the absorber is higher than the hydrophilicity of the fibers constituting the lower layer of the topsheet.

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