JP2007044124A - Absorbent articles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent product which can reduce a hydrophilic treatment cost to the covering sheet of an absorbent and has the high selection freedom degree of a hot-melt class adhesive for adhering a surface sheet, the draping sheet, etc. <P>SOLUTION: The absorptive article comprises the liquid-permeable surface sheet 1 and the liquid holding absorbent 2 arranged on the inferior surface side of the surface sheet 1. The surface sheet 1 consists of a sheet which undergoes the hydrophilic treatment of a monolayer or multilayers, wherein at least one of which undergoes the hydrophilic treatment for making hydrophilicity liable to fall off by liquid permeation, and the absorbent 2 comprises a liquid holding absorptive core 3 covered with the cover sheet 4 consisting of a spunbonded fabric which is liquid-permeable and hydrophobic. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to absorbent articles such as disposable diapers, sanitary napkins, and incontinence pads.

  Absorbent articles such as disposable diapers and sanitary napkins are generally formed by covering a pile of absorbent fibers such as fluff pulp and superabsorbent polymer particles with absorbent paper such as tissue paper. And a liquid-permeable surface sheet on the upper surface side (skin contact surface side) of the absorber. The main reason for covering the fiber stack with the absorbent paper is to maintain the shape of the fiber stack and to prevent the particles of the superabsorbent polymer from falling off the absorber.

  The following Patent Document 1 describes that instead of covering a piled body containing particles of fluff pulp and superabsorbent polymer with tissue paper, the piled body is coated with a covering sheet made of a nonwoven fabric. Yes.

Special table 2002-520882 gazette

  However, in the absorbent article described in Patent Document 1, in order to ensure sufficient absorption performance, the surface sheet and the covering sheet are subjected to a hydrophilization treatment in which hydrophilicity is unlikely to decrease due to liquid permeation. And the cost which performs the hydrophilic treatment which hydrophilicity does not fall easily by liquid permeation with respect to a coating sheet is required, and a manufacturing cost becomes high.

  In absorbent articles, the surface sheet and the covering sheet or the covering sheet and the absorbent core are often joined by a hot-melt adhesive, but the covering sheet is subjected to a hydrophilic treatment. If this is done, in addition to the decrease in adhesive strength due to the effect of the hydrophilizing agent, moisture easily enters the interface between the fiber surface and the hot melt adhesive. Adhesive strength decreases. Therefore, for example, a special type of hot melt adhesive such as a delayed crystal type hot melt adhesive (a hot melt adhesive that does not harden immediately after application but gradually stiffens while entangled with the constituent fibers) is used. It is necessary to use it, and the degree of freedom in selecting a hot-melt adhesive is low and the manufacturing cost is high.

  Accordingly, an object of the present invention is to provide an absorbent article that can reduce the hydrophilic treatment cost of the absorbent covering sheet and has a high degree of freedom in selecting a hot-melt adhesive that adheres the surface sheet, the covering sheet, and the like. There is to do.

  As a result of extensive research, the present inventor has made at least one layer of the surface sheet a hydrophilic treatment that tends to decrease the hydrophilicity due to liquid permeation, and the absorbent covering sheet is composed of a liquid-permeable and hydrophobic nonwoven fabric. It has been found that the above-mentioned purpose can be achieved.

  The present invention has been made on the basis of the above knowledge, and includes a liquid-permeable surface sheet and a liquid-retaining absorbent disposed on the lower surface side of the surface sheet. It is composed of a sheet having a plurality of layers subjected to a hydrophilic treatment, and at least one of the sheets is subjected to a hydrophilic treatment in which hydrophilicity is liable to decrease due to liquid permeation, and the absorbent body has a liquid-retaining absorbent core. The above-mentioned object is achieved by providing an absorbent article that is configured to be coated with a coating sheet made of a liquid-permeable and hydrophobic nonwoven fabric.

  According to the absorbent article of the present invention, the hydrophilic treatment cost of the absorbent covering sheet can be reduced, and the degree of freedom in selecting a hot-melt adhesive that adheres the top sheet, the covering sheet, and the like is high.

  Hereinafter, the absorbent article of this invention is demonstrated based on the preferable embodiment. The absorbent article of the present invention is mainly used for absorbing and holding excretory body fluids such as urine and menstrual blood. The absorbent article of the present invention includes disposable diapers, sanitary napkins, incontinence pads, etc., but is not limited thereto, and widely includes articles used for absorbing liquid discharged from the human body. .

The absorbent article of the present invention will be specifically described based on an embodiment thereof with reference to the drawings.
In this embodiment, as shown in FIG. 1, a liquid-retaining absorbent body 2 is disposed below the liquid-permeable top sheet 1, and a liquid-impermeable back sheet (underneath the absorbent body 2 ( (Not shown) is arranged. At the peripheral edge of the absorbent body 2, the top sheet 1 and the back sheet are joined. Such a structure is known.
In the absorbent article of the present invention, “upper surface side” means “skin contact surface side”, and “lower surface side” means “non-skin contact surface side”.

The surface sheet 1 is a sheet having a single layer or a plurality of layers subjected to hydrophilization treatment, and at least one layer thereof is subjected to a hydrophilization treatment (hereinafter referred to as non-durable hydrophilization treatment) in which the hydrophilicity tends to decrease due to liquid permeation. It has been subjected. “Non-durable hydrophilic treatment” refers to a treatment in which the degree of hydrophilicity of the sheet or constituent fiber expressed by the hydrophilic treatment is likely to be reduced by contact with water.
In the surface sheet 1 composed of a plurality of layers, if at least one layer is subjected to non-durable hydrophilization treatment, the hydrophilicity of the other layers is less likely to decrease due to liquid permeation (hereinafter referred to as durable hydrophilization treatment). ) May be given. “Durable hydrophilization treatment” refers to a treatment in which the degree of hydrophilicity of the sheet or constituent fiber expressed by the hydrophilization treatment is less likely to be reduced by contact with water.

In the non-durable hydrophilic treatment or the durable hydrophilic treatment, there are a case where each layer is formed into a sheet shape and then subjected to a hydrophilic treatment, and a case where each layer is formed from constituent fibers that have been subjected to a hydrophilic treatment in advance.
The layer subjected to the durable hydrophilization treatment includes not only the layer subjected to the durable hydrophilization treatment, but also the constituent fiber subjected to the durable hydrophilization treatment and the constituent fiber subjected to the non-durable hydrophilization treatment. A mixed layer is also included.
In the lower layer of the two-surface sheet, the mixing ratio (weight ratio) between the constituent fibers subjected to the durable hydrophilization treatment and the constituent fibers subjected to the non-endurance hydrophilic treatment is preferably 70:30 to 10 : 90.

As the hydrophilizing oil used for non-durable hydrophilization treatment or durable hydrophilization treatment, for example, anionic, cationic, amphoteric and nonionic surfactants having various molecular weights may be used alone or in combination. it can.
Particularly preferable examples of the hydrophilizing oil used in the non-durable hydrophilization treatment include polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, and sorbitan fatty acid ester. Particularly preferable examples of the hydrophilizing oil used for the durable hydrophilization treatment include polyglycerin fatty acid ester, polyether-polyester block copolymer, polyether-modified silicon, and ethylene oxide-added polyhydric alcohol.

Whether the constituent fiber forming each layer is a fiber subjected to a durable hydrophilic treatment or a fiber subjected to a non-durable hydrophilic treatment is determined, for example, based on the sedimentation time measured by the following method. Can do.
<Method of measuring sedimentation time>
5.0 ± 0.1 g of fibers uniformly loosened for each type is packed so as not to protrude into the cylindrical wire container described in ASTM D1117-80 5.2.1.1. The time T1 (s) from when floating in a cylindrical cup container with a diameter of 115 mm filled with 1000 cc of ion exchange water until the entire cylindrical wire container completely sinks below the surface of the ion exchange water is measured.

Next, the fiber is taken out from the cylindrical wire container and air-dried at room temperature. After confirming that the moisture has been completely removed by air drying, use the air-dried fiber to perform the same operation as above, and then turn the cylindrical wire container filled with the air-dried fiber to the water surface in the cylindrical cup container filled with ion-exchanged water. Force down completely.
Next, the fiber is taken out from the cylindrical wire container and air-dried at room temperature. After confirming that the moisture has been completely removed by air drying, use the air-dried fiber to perform the same operation as above, and then turn the cylindrical wire container filled with the air-dried fiber to the water surface in the cylindrical cup container filled with ion-exchanged water. The time T2 (s) until it completely sinks down is measured.
Times T1 (s) and T2 (s) were obtained by performing the same measurement three times on the same fiber and calculating an average value.

Times T1 (s) and T2 (s) are measured by the above method. If the time T1 (s) is a fiber of 200 seconds or less, it is determined that the fiber is a hydrophilic fiber. That is, it is determined that the fiber has been subjected to durable hydrophilic treatment or non-durable hydrophilic treatment. And if time T2 (s) used as the 3rd liquid contact after being settled twice in water is 200 seconds or less, it judges that it is the fiber which performed durable hydrophilic treatment, and exceeds 200 seconds. If there is, it is determined that the fiber has been subjected to non-durable hydrophilic treatment.
The time T1 (s) of the fiber subjected to the durable hydrophilic treatment and the fiber subjected to the non-durable hydrophilic treatment is preferably within 100 seconds, more preferably within 50 seconds, and even more preferably within 10 seconds. Further, the time T2 (s) of the fiber subjected to the durable hydrophilization treatment is preferably 150 seconds or less, and more preferably 100 seconds or less, from the viewpoint of liquid permeability.

A contact angle with ion-exchanged water may be used as a reference for judging a fiber subjected to a durable hydrophilic treatment and a fiber subjected to a non-durable hydrophilic treatment.
The contact angle is an angle between the water droplet on the fiber and the surface of the fiber, and the fiber having the smaller contact angle can be determined to have high hydrophilicity.
Specifically, the contact angles before and after liquid permeation are measured. The contact angle may be measured in a fiber state or a nonwoven fabric state. In the state of the nonwoven fabric, a total of 50 g of ion-exchanged water is allowed to pass through a circle having a diameter of 10 mm, dried at 30 ° C. for about 2 hours, and measured for the contact angle of the ion-exchanged water. To do.

The contact angle before liquid permeation between the fiber subjected to the durable hydrophilic treatment and the fiber subjected to the non-durable hydrophilic treatment is preferably 30 ° to 80 °. If the contact angle after liquid permeation is 35 ° to 80 °, it is determined that the fiber has been subjected to durable hydrophilic treatment, and the contact angle after liquid permeation is 20 ° or more larger than the contact angle before liquid permeation. If it is 50 ° to 100 °, it is determined that the fiber has been subjected to non-durable hydrophilic treatment.
The measurement method of the contact angle before liquid permeation in the nonwoven fabric is as follows.

[Measurement method of contact angle]
Measurement was performed using a microscope VH-8000 manufactured by Keyence Corporation with a medium-magnification zoom lens (with illumination ring) tilted to 90 ° and setting the magnification at 500 times. The measurement sample was cut into a size of 150 mm in the MD direction and 70 mm in the CD direction while the upper and lower layers were integrated. The measurement environment was 20 ° C./50% RH, and the measurement sample was set on the measurement stage so that the measurement surface can 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 can be observed from a direction perpendicular to the fiber length direction.

  When determining the contact angle of the constituent fibers of the first layer, use the fibers on the surface of the first layer as the measurement target, and when determining the contact angle of the constituent fibers of the second layer, use the surface of the second layer (as the top sheet). In this case, the measurement target is the fiber on the surface facing the absorber. 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 first layer and the second layer separately for some reason, the contact angle is measured on a non-overlapping surface.

  Next, 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) on the measurement sample set on the measurement stage. An image is captured (as much as possible in 2 to 3 seconds). The reason why it is necessary to capture the 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 the contact angle from changing due to the hydrophilizing oil. is there. The contact angles of 10 observation results with clear focus at both ends or one end of the water droplet were measured, and the average value thereof was defined as “contact angle”. Note that the contact angle can be measured by taking out each constituent fiber from the upper and lower layers instead of the top sheet.

This contact angle measurement needs to be performed with attention to the following items.
(A) The contact angle on the upper surface of the fiber is measured. In other words, water droplets placed on the fiber are targeted, and measurement is not performed on water droplets that hang down to the bottom of the fiber or water droplets that span two or more fibers.
(B) When the fiber has a fine crimp such as a spiral shape, the measurement is performed 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, when the hydrophilicity is high, water droplets are unlikely to stay on the fiber during measurement and may flow. In that case, the “contact angle” is determined according to the flow rate.

-The total number of measurements (total number of measurement points where contact between the fiber and water was observed, the sum of cases where water droplets flowed and did not flow after contact, and so on) until the measurement value reached 10 When less than 40% has flowed, the average result of 10 measured values is defined as “contact angle”.
・ If 40% or more of the total number of measurements has flowed by the time the measurement value reaches 10, or if 40% or more of the total number of measurements has flowed when 10 measurements have been taken, The “contact angle” is 20 ° or less.

If the specific example of the structure of the surface sheet 1 is given, in the surface sheet 1 of single layer structure, the non-durable hydrophilization process is performed to the whole layer.
As the surface sheet 1 having a two-layer structure, for example, the upper layer is subjected to non-durable hydrophilic treatment, and the lower layer is subjected to durable hydrophilic treatment, and the non-durable hydrophilic treatment constituent fiber, And a two-layer structure in which a non-durable hydrophilic treatment is applied to the upper layer and a durable hydrophilic treatment is applied to the lower layer.

In the surface sheet of the absorbent article of the present invention, “upper layer” means a layer on the skin contact surface side, and “lower layer” means a layer on the non-contact surface side.
The top sheet 1 can be composed of three or more layers.
In the surface sheet 1 composed of a plurality of layers, the respective layers are integrated by a known integration means, for example, an adhesive, fiber entanglement, heat fusion, or the like.

  As the surface sheet 1, for example, various webs, nonwoven fabrics, and the like can be used. Examples of the web include a card web obtained by opening a short fiber with a card machine, an airlaid web obtained by depositing the short fiber by conveying it in an air stream, and a continuous filament spun by melt spinning with an ejector. A spunbond web obtained by pulling and depositing is mentioned. Examples of the nonwoven fabric include air-through nonwoven fabric, spunlace nonwoven fabric, airlaid nonwoven fabric, spunbond nonwoven fabric, and meltblown nonwoven fabric.

  The constituent fibers of the topsheet 1 are obtained by subjecting hydrophobic fibers to a hydrophilic treatment. In addition, it is not necessary that all the constituent fibers are those obtained by subjecting hydrophobic fibers to hydrophilic treatment, and some of the constituent fibers may include hydrophobic fibers that have not been subjected to hydrophilic treatment.

Examples of the hydrophobic fibers include polyolefin fibers such as polyethylene and polypropylene, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, polyamide fibers, acrylic fibers, and a core composed of a combination of two or more of these resins. Examples of the composite fiber include a sheath type composite fiber and a side-by-side type composite fiber.
The hydrophobic fibers may be short fibers or continuous filaments depending on the method for producing each layer of the topsheet 1 and the performance required for these layers. The fineness is generally 0.1 to 16.5 dtex, particularly preferably 0.8 to 7.8 dtex.

As shown in FIG. 1, the absorbent body 2 includes an absorbent core 3 and a single cover sheet 4 that covers the absorbent core 3.
The upper surface side of the absorbent core 3 is covered with a central portion (a half portion in the width direction) 4c of the cover sheet 4 in the width direction. In addition, the lower surface side of the absorbent core 3 is formed by absorbing both sides in the width direction of the covering sheet 4 extending in the width direction from the upper surface side of the absorbent core 3 (each about a quarter of the width direction) 4a and 4b. Folded to the lower surface side of the core 3 and covered by overlapping a part of both side portions 4a and 4b of the covering sheet 4. In this way, the upper and lower surfaces and the left and right side surfaces of the absorbent core 3 are covered with the covering sheet 4.

  The absorbent core 3 and the covering sheet 4 are formed so that their longitudinal dimensions are substantially the same or the absorbent core 3 is shorter. At the front and rear end edges in the longitudinal direction of the absorbent body 2, the center part 4 c located on the upper surface of the core 2 of the covering sheet 4 is joined to both side parts 4 a and 4 b located on the lower surface of the absorbent core 3, A closed sealing portion is formed. The absorbent core 2 is not substantially exposed from the sealing portion.

For the absorbent core 3, a material usually used in the technical field can be used without particular limitation. For example, the absorptive core 3 is comprised from the laminated fiber layer of a pulp, the web of the long fiber which has hydrophilic property, or these laminated bodies.
The pulp accumulation layer constituting the absorbent core 3 is obtained by depositing pulp fibers, or is made of a nonwoven fabric using pulp fibers as a raw material. When the pile fiber layer is obtained by depositing pulp fibers, it is possible to use the same fiber layer as that used as an absorbent in a conventional absorbent article. it can. When the pile fiber layer is made of a nonwoven fabric made from pulp fibers, for example, an airlaid nonwoven fabric can be used as the nonwoven fabric.

  The hydrophilic long fibers of the web constituting the absorbent core 3 are inherently hydrophilic long fibers and are not inherently hydrophilic, but are subjected to a hydrophilic treatment. Both long fibers imparted with hydrophilicity are included. Preferred long fibers are inherently hydrophilic long fibers, and particularly preferred are acetate and rayon long fibers.

  The absorbent core 3 is composed of a single-layer structure composed of a laminated fiber layer of pulp, a single-layer structure composed of a hydrophilic long fiber web or a laminate thereof, or a long fiber having hydrophilicity with pulp fibers. A one-layer structure consisting of a mixed laminate of the above is used. Further, a combination of these two layers may be used.

  A superabsorbent polymer can be embedded and supported in the absorbent core 3. “The superabsorbent polymer is buried and supported” means that the superabsorbent polymer enters the space formed by the pulp and long fibers constituting the absorbent core 3 and is also highly absorbent even by the wearer's intense movement. This refers to the state where the polymer is unlikely to move or fall off.

  As the superabsorbent polymer, a particulate polymer is generally used, but a fibrous polymer may be used. When particulate superabsorbent polymer is used, if the shape is irregular type, lump type, or cocoon type, it is buried at the basis weight of the same amount or more and 10 times or less with respect to the piled fiber layer or web It can be supported. Further, in the case of a spherical particle aggregation type or a spherical type, it can be embedded and supported with a basis weight of the same amount or more and five times or less with respect to the stacked fiber layer or the web.

  The covering sheet 4 is made of a nonwoven fabric having liquid permeability and hydrophobicity. “Hydrophobic” is a hydrophobic fiber if the fiber constituting the nonwoven fabric is measured for the time T1 (s) by the method for measuring the settling time described above, and the fiber has a time T1 (s) of 200 seconds or more. Judge. Alternatively, if the contact angle is 80 ° or more by measuring the contact angle with the above ion-exchanged water, it is determined that the surface is hydrophobic.

Examples of the nonwoven fabric forming the covering sheet 4 include an air-through nonwoven fabric, a spunbond nonwoven fabric, a spunlace nonwoven fabric, a meltblown nonwoven fabric, a resin bond nonwoven fabric, and a nonwoven fabric obtained by combining these nonwoven fabrics.
Examples of the constituent fibers of the covering sheet 4 include fibers that are inherently hydrophobic and fibers obtained by subjecting hydrophilic fibers to a hydrophobic treatment.

Examples of the inherently hydrophobic fiber include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polyamide resins, acrylic resins, and vinyl resins.
Examples of the hydrophilic fiber suitable for the hydrophilic fiber subjected to the hydrophobic treatment include pulp fiber, acetate fiber and rayon fiber. Examples of the hydrophobizing agent include silicone oils, fluorine oils, and wax oils.

The covering sheet 4 and the absorbent core 3 are bonded to each other on the upper surface or the lower surface of the absorbent core 3 by an adhesive (not shown).
The top sheet 1 and the covering sheet 4 are joined by an adhesive (not shown) on a part or almost the whole of the boundary surface.

  As said adhesive agent, what is normally used in order to join between the structural members of an absorbent article can be especially used without a restriction | limiting. For example, a hot melt adhesive can be used. The hot melt pressure-sensitive adhesive contains a base polymer composed of a styrene-isoprene-styrene block copolymer, a styrene-butadiene-styrene block copolymer, a styrene-ethylene-butylene-ethylene copolymer, an olefin copolymer, or the like. Is preferred.

  As the back sheet, materials that are usually used in absorbent articles can be used without particular limitation. For example, a thermoplastic resin film or a laminate of the film and a nonwoven fabric can be used. It may have water vapor permeability.

  In this embodiment, when the body fluid W adheres to the top sheet 1 as shown in FIG. 2A, the hydrophilicity used for the non-durable hydrophilic treatment in the top sheet 1 as shown in FIG. The chemical oil moves together with the body fluid W to the covering sheet 4 of the absorbent body 2. Although the covering sheet 4 is formed from a hydrophobic nonwoven fabric, the covering sheet 4 is partially hydrophilicized by the hydrophilizing oil transferred from the top sheet 1 and becomes hydrophilic. Therefore, the body fluid W transferred from the top sheet 1 moves to the absorbent core 3 of the absorbent body 2 and is retained. In the present embodiment, such a liquid absorption mechanism can ensure sufficient absorption performance in actual use.

  According to this embodiment, at least one layer of the surface sheet 1 is subjected to non-durable hydrophilic treatment, and the absorbent core 3 of the absorbent body 2 is covered with the covering sheet 4 made of a hydrophobic nonwoven fabric. Therefore, the surface sheet 1 does not necessarily need to be subjected to a durable hydrophilic treatment, and the covering sheet 4 need not be subjected to a hydrophilic treatment. Therefore, the hydrophilization cost for the covering sheet 4 can be reduced.

  Further, since the surface sheet 1 and the covering sheet 4 are easily lost in hydrophilicity or do not have hydrophilicity, it is difficult for moisture to enter the interface between the surface of the fiber and the hot melt adhesive. It is not necessary to use a delayed crystal type as the hot melt adhesive used for bonding between the cover sheet 4 and the cover sheet 4 and between the cover sheet 4 and the absorbent core 3, and a normal one can be used. for that reason. The degree of freedom in selecting hot melt adhesives is high.

Although one embodiment of the absorbent article of the present invention has been described above, the absorbent article of the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. is there.
The absorbent article of the present invention is not limited to disposable diapers, and can also be applied to sanitary napkins, incontinence pads, and the like. As these specific configurations, various configurations can be adopted.
In the absorbent body, the form of covering the absorbent core with the covering sheet is not limited as long as at least the upper surface side of the absorbent core is coated. For example, it can be set as the form by which the width direction center part of the lower surface side of an absorptive core is not coat | covered. You may coat an absorptive core using two nonwoven fabrics.

  Hereinafter, the absorption performance in the absorbent article of the present invention will be described in more detail by way of specific examples. The present invention is not limited to these examples.

[Example 1]
-Surface sheet The surface sheet used was a two-layered nonwoven fabric. The upper layer is a sheet of core-sheath type composite fiber (fiber A) having a fineness of 2.0 dtex made of polyethylene terephthalate (core) / polyethylene (sheath) subjected to non-durable hydrophilic treatment with octyl alcohol monophosphate salt by a card method. The basis weight is 10 gsm. The lower layer is non-durable with 70% by weight of core-sheath type composite fiber (fiber B) having a fineness of 5.6 dtex and made of polypropylene (core) / polyethylene (sheath) subjected to durable hydrophilic treatment with polyglycerin fatty acid ester and sorbitan fatty acid ester. 30% by weight of a core-sheath type composite fiber (fiber C) having a fineness of 5.6 dtex made of polyethylene terephthalate (core) / polyethylene (sheath) subjected to a hydrophilic treatment is formed into a sheet by the card method, and the basis weight is 10 gsm. It is what. The upper layer and the lower layer are joined by thermally bonding the intersections of the constituent fibers with hot air.

-Absorber What used the basis weight of 187 gsm and the superabsorbent polymer for the absorptive polymer was used as the absorptive core.
・ Coating sheet As a coating sheet, both sides of a melt-blown nonwoven fabric using polypropylene fibers are sandwiched between spunbond nonwoven fabrics using polypropylene fibers and composited by heat embossing, and a non-hydrophilic nonwoven fabric with a basis weight of 13 gsm Was used.

[Example 2]
The mixing ratio (weight ratio) of the fiber B and the fiber C in the lower layer is the same as that of the example 1 except that the fiber B: fiber C = 50%: 50%.
Example 3
It has the same configuration as that of Example 1 except that the lower layer is composed only of the fibers B.

〔Evaluation methods〕
A 210 mm long absorbent core is covered with a cover sheet, a top sheet is placed on it, a sample cut to 210 mm in length is produced, and the sample is attached to a sloped base at an angle of 30 ° with one end in the longitudinal direction down I attached. 30 g of physiological saline was injected with a funnel almost at the center in the width direction at a position 150 mm from the lower end of the absorbent core, and this was repeated at intervals of 5 minutes. And at each injection | pouring, the distance which a liquid flows on an absorber from an injection | pouring point was measured. It shows that absorption performance is so good that this liquid flow distance is short.

The evaluation results of each example are shown in [Table 1] below.
In addition, “1 average”, “2 average”, and “3 average” are those of Examples 1-1 to 1-3, Examples 2-1 to 2-3, and Examples 3-1 to 3-3, respectively. Average values are shown.

〔Evaluation results〕
As is apparent from the results shown in [Table 1], the non-durable hydrophilization treatment, in which the hydrophilicity is liable to be lowered by liquid permeation, is at least in one layer even in the case of an absorbent body in which the absorbent core is coated with a hydrophobic nonwoven fabric. Absorption performance can be demonstrated by using the applied surface sheet, and the upper layer has been subjected to non-durable hydrophilic treatment, and the lower layer has been subjected to durable hydrophilic treatment and non-durable hydrophilic It was found that the absorption performance could be further improved by using a surface sheet composed of a mixed layer with the component fibers subjected to the chemical treatment.

FIG. 1 is a longitudinal sectional view in the width direction of an embodiment of an absorbent article of the present invention. 2A and 2B are partially enlarged views of FIG. 1, in which FIG. 2A is a schematic diagram illustrating a state before liquid absorption, and FIG. 2B is a schematic diagram illustrating a state after liquid absorption.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface sheet 2 Absorber 3 Absorbent core 4 Cover sheet

Claims (4)

A liquid-permeable surface sheet, and a liquid-retaining absorbent disposed on the lower surface side of the surface sheet,
The surface sheet is composed of a single layer or a plurality of layers subjected to hydrophilization treatment, and at least one layer thereof is subjected to hydrophilization treatment in which the hydrophilicity is liable to decrease due to liquid permeation,
The absorbent body is an absorbent article in which a liquid-retaining absorbent core is coated with a coating sheet made of a liquid-permeable and hydrophobic nonwoven fabric.   The top sheet is composed of the two layers of sheets, and the upper layer is subjected to a hydrophilic treatment in which the hydrophilicity is liable to decrease due to liquid permeation, and the lower layer is subjected to a hydrophilization treatment in which the hydrophilicity is difficult to decrease due to liquid permeation. The absorbent article according to claim 1, comprising a mixed layer of the applied constituent fibers and the constituent fibers subjected to a hydrophilization treatment in which hydrophilicity tends to decrease due to liquid permeation.   In the lower layer of the surface sheet, the mixing ratio of the constituent fiber subjected to the hydrophilic treatment that is difficult to reduce hydrophilicity due to liquid permeation and the constituent fiber subjected to the hydrophilic treatment that is likely to decrease hydrophilicity due to liquid permeation is The absorbent article according to claim 2, which is 70:30 to 10:90. The absorbent article according to any one of claims 1 to 3, wherein a hot melt adhesive is used between the top sheet and the covering sheet and between the covering sheet and the absorbent core.

Images