KR101148537B1 - Topsheet for absorbent article - Google Patents

Abstract

The surface sheet of the absorbent article of the present invention is composed of a laminated nonwoven fabric 20 having an upper layer 21 disposed on the skin side and a lower layer 22 disposed on the absorber 4 side, and the upper layer before liquid permeation. The hydrophilicity of the lower layer 22 is higher than or substantially the same as that of (21), and after liquid permeation, the hydrophilicity of the upper layer 21 is higher than that of the lower layer 22.

Absorbent, Laminated Nonwoven, Hydrophilicity

Description

Surface sheet of absorbent article {Topsheet for absorbent article}

BRIEF DESCRIPTION OF THE DRAWINGS It is a top view which shows the surface sheet as one Embodiment of the surface sheet of the absorbent article of this invention, and the sanitary napkin using the same.

FIG. 2 is a cross-sectional view taken along the line II of FIG. 1.

It is sectional drawing which shows typically the cross section of the thickness direction of the surface sheet shown in FIG.

4A and 4B are views for explaining the function of the surface sheet of the present invention. FIG. 4A is a conceptual diagram showing a liquid permeation state at an early stage after the start of use. It is a conceptual diagram which shows the liquid permeation state after permeation.

It is explanatory drawing for demonstrating the adjustment method of the sample for a measurement used for the measurement of the contact angle after liquid permeation.

It is a schematic cross section which shows an example of the specific cross-sectional structure of the thickness direction of a surface sheet.

It is a schematic cross section which shows another example of the specific cross-sectional structure of the thickness direction of a surface sheet.

8A, 8B, 8C, and 8D are diagrams for explaining a method for measuring contact angles, and FIGS. 8A and 8B are views in which the contact angle is preferably measured. 8A 'and FIG. 8B' are the figures which show the fiber after the droplet on fiber evaporated, and is used in order to measure the tangent of the fiber surface in the boundary part with water droplets.

The present invention relates to absorbent articles such as sanitary napkins, panty liners, incontinence pads, disposable diapers, and surface sheets which are preferably used for the skin contact surfaces thereof.

The surface sheet of absorbent articles, such as sanitary napkins and disposable diapers, smoothly transfers discharge from the human body, such as menstrual blood and urine, to the absorbent body, and reverse movement of the liquid once absorbed by the absorbent body (wet back). ) Is required.

A surface sheet of an absorbent article, which is a surface sheet having an upper layer disposed on the skin side and a lower layer disposed on the absorber side, and having a hydrophilicity lower than that of the upper layer, and used for hydrophilization of the constituent fibers of the lower layer. A surface sheet having a higher durability to the liquid of i) than the durability of the hydrophilic oil agent used for the hydrophilization of the constituent fibers of the upper layer is proposed (see Japanese Patent Laid-Open No. 2002-065738). According to this surface sheet, in an early stage after the start of use, the liquid can be smoothly transferred to the absorber by the gradient of the hydrophilicity between the upper layer and the lower layer.

However, since the hydrophilicity of the upper layer, which is originally lower than that of the lower layer, is further lowered after a certain amount of the liquid has passed through the surface sheet, the liquid discharged (supplied) on the surface sheet thereafter is There is a problem that it is difficult to penetrate into the surface sheet and does not smoothly migrate to the absorber, or flows through the surface of the surface sheet. In addition, even after a certain amount of the liquid has passed through the surface sheet, the hydrophilicity of the lower layer is maintained higher than that of the upper layer, and especially when a large amount of the liquid is absorbed into the absorber, the liquid flows from the absorber to the lower layer. In addition, there is a concern that the surface sheet may move backward.

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface sheet capable of keeping the liquid permeability stable during use and preventing the surface flow and backflow of the liquid for a long time during use and an absorbent article using the same.

The present invention consists of a laminated nonwoven fabric having an upper layer disposed on the skin side and a lower layer disposed on the absorber side, and before the liquid permeation, the lower layer side has a higher hydrophilicity or substantially the same as the upper layer than the upper layer, and after the liquid permeation. In the above, the said objective is achieved by providing the surface sheet of the absorbent article in which the said upper layer has a higher hydrophilicity than the said lower layer.

The present invention consists of a laminated nonwoven fabric having an upper layer disposed on the skin side and a lower layer disposed on the absorber side, and before the liquid permeation, the lower layer side has a higher hydrophilicity or substantially the same as the upper layer than the upper layer, and after the liquid permeation. In the above object, the upper layer has a hydrophilic surface sheet having a higher hydrophilicity than the lower layer, a liquid-impermeable back sheet, and an absorbent article having a liquid-retaining absorber interposed between these sheets. Will be achieved.

<Embodiment of the Invention>

 EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated, referring drawings based on the preferable embodiment.

The sanitary napkin 1 shown in FIG. 1 and FIG. 2 is one Embodiment of the absorbent article of this invention, The surface sheet 2 as one Embodiment of the surface sheet of the absorbent article of this invention, The liquid impermeable back surface It is provided with the sheet | seat 3 and the liquid-retaining absorbent body 4 interposed between these sheets, and are formed substantially longitudinally.

The surface sheet 2 has a longitudinal direction and a width direction, and the center area | region in the width direction of the sanitary napkin 1 is shown in the state which made the longitudinal direction match with the longitudinal direction of the sanitary napkin 1 (FIG. 1). Part indicated by an oblique line). The surface sheet 2 has a pair of water repellent or liquid impermeable side forming sheets 5 successively formed at both side edge portions in the longitudinal direction, and is composited with these sheets 5 and 5 together. The surface sheet 6 is formed. As for the composite surface sheet 6, the both edge parts 61 and 61 are adhesively fixed between the absorber 4 and the back sheet 3 in the longitudinal side part of the sanitary napkin 1, Both ends 62 and 62 in the longitudinal direction are fixed to the back sheet 3 extending from the end edge of the absorber 4 at both ends in the longitudinal direction of the sanitary napkin 1 by known bonding means. It is.

As shown in the schematic cross section shown in FIG. 3, the surface sheet 2 consists of the laminated nonwoven fabric 20 which has the upper layer 21 arrange | positioned at the skin side, and the lower layer 22 arrange | positioned at the absorber 4 side. The upper layer 21 and the lower layer 22 both consist of a fiber aggregate. The fiber assembly here is a concept including not only the nonwoven fabric by various manufacturing methods but the fiber web, paper, etc. before nonwoven fabric obtained by the card method or the air laid method. The upper layer 21 and the lower layer 22 may be laminated and then laminated to be a nonwoven fabric 20, or any one layer or both layers may be laminated in a fibrous web state before being nonwoven and then laminated to a nonwoven fabric ( 20) may be used.

The upper layer 21 and the lower layer 22 are laminated to each other and partially bonded to each other. In addition, the upper layer 21 and the lower layer 22 are in close contact with each other, or the nonwoven fabrication process after laminating the upper layer 21 and the lower layer 22 (air) It is integrated simultaneously with nonwoven fabric by the air-through process and the spun lacing process.

The lower layer 22 in the surface sheet 2 has a hydrophilicity higher than or substantially the same as the upper layer 21 in the dry state before allowing the liquid to pass through the surface sheet 2.

Accordingly, in the early stage after the start of the use of the sanitary napkin (absorbent article) using the surface sheet 2, as shown in FIG. 4A, the liquid A is disposed on a specific portion of the surface sheet 2. When () is discharged (supplied), the liquid does not diffuse much from the site, as shown by arrow A ', and soaks smoothly into the upper layer 21 in which the hydrophilicity is relatively high, and the upper layer 21 Transitions smoothly to the lower layer 22, and is finally absorbed by the absorber (4). When the lower layer 22 has a higher hydrophilicity than the upper layer 21, it is preferable because the lower layer 22 transitions more smoothly by the hydrophilic gradient from the upper layer 21 to the lower layer 22 having a higher hydrophilicity.

In this way, the liquid A discharged | emitted on the surface sheet 2 does not remain on the surface of a surface sheet, but moves to the absorber 4 promptly. Therefore, a dry feeling is obtained on the surface of the surface sheet 2, and when absorbing the liquid which has a color such as acupuncture points, it is excellent in the effect of concealing so that the color will not stand out. On the other hand, in the early stage after the start of use, since there is room in the absorbing power (liquid absorption capacity) of the absorber 4, even if the hydrophilicity of the lower layer 22 is high, backflow does not occur.

As described above, the surface sheet 2 has a hydrophilicity higher than or substantially the same as that of the lower layer 22 before the liquid permeation (before wetting), but after the liquid permeation, the lower layer ( The hydrophilicity of the upper layer 21 is higher than that of 22).

That is, in the upper layer 21 and the lower layer 22 in the surface sheet 2, there is a difference in the durability of the hydrophilicity to the liquid, while the hydrophilicity of the upper layer 21 decreases relatively gently even when contacted with the liquid. For the lower layer 22, the hydrophilicity decreases relatively quickly due to contact with the liquid. Therefore, when a sufficient amount of the liquid is allowed to pass through the surface sheet 2, the high and low relationship between the hydrophilicity of the upper layer 21 and the lower layer 22 is reversed.

The case where said sufficient amount of liquid permeate | transmits is the inside of the case where the 10g ion-exchange water permeate | transmitted 5 times in the 10 mm diameter circle, for example. This liquid amount is a permeation amount of ion-exchanged water which is considered to be sufficient to reverse the high and low hydrophilic relationship between the upper layer 21 and the lower layer 22. When the surface sheet 2 is used for absorbent articles such as sanitary napkins, It is not the amount of permeate that is assumed. In other words, when a sanitary napkin or the like is used in reality, the high and low relations of the hydrophilicity of the upper layer 21 and the lower layer 22 do not necessarily need to be reversed.

When the surface sheet 2 has the structure which combined the upper layer 21 with high hydrophilic durability, and the lower layer 22 with low hydrophilic durability, which the hydrophilic high-lowness relationship reverses when sufficient liquid permeate | transmits, The following effects appear.

That is, as shown to FIG. 4B, when the liquid A discharged on the specific site | part of the surface sheet 2 permeate | transmits the surface sheet 2 by a certain quantity, the lower layer 22 will be hydrophilic in durability. Since it is low, the hydrophilicity of the site | part (part shown with a dotted line) P which permeate | transmitted liquid falls comparatively large. On the other hand, since the upper layer 21 has high hydrophilic durability, the decrease in hydrophilicity is relatively small even at the site where the liquid has permeated.

Therefore, it is satisfactorily maintained that the liquid penetrates into the upper layer 21, and the liquid discharged on the surface sheet penetrates into the upper layer 21 satisfactorily. This prevents the liquid from flowing through the surface of the surface sheet 2 and prevents the liquid from leaking from the sides or back of the napkin.

On the other hand, since the hydrophilicity of the site | part (part shown with a dotted line) P which the some amount of liquid permeate | transmitted in the lower layer 22 falls, the liquid B which has already shifted to the absorber 4 The phenomenon (backflow) which penetrates the lower layer 22 and moves back to the surface hardly occurs.

On the other hand, the liquid that has soaked into the upper layer 21 is difficult to penetrate at the portion (P in the figure) through which a certain amount of liquid has already penetrated, but as indicated by the arrow A " It penetrates into the site | part in which the existing hydrophilicity does not fall by the gradient of hydrophilicity, and it moves to an absorber favorably.

Here, the height of the hydrophilicity of the upper layer and the lower layer before the liquid permeation is preferably the height of the hydrophilicity of the constituent fibers, and can be judged by using the contact angle of the 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 judged that the smaller the contact angle is, the higher the hydrophilicity is. In addition, when the difference of contact angle is less than +/- 3 degrees, it is judged that hydrophilicity is substantially the same as a substantially same contact angle.

In addition, the height of the hydrophilicity of the upper layer and the lower layer after liquid permeation is preferably the height of the hydrophilicity of the constituent fibers, and can be judged by using the contact angle of ion exchanged water with respect to the constituent fibers after liquid permeation as an index. In detail, the contact angle of ion-exchange water with respect to the constituent fiber after permeating 10g of ion-exchange water 5 times (after liquid permeation) in the circle of diameter 10mm can be judged as an index. In other words, it can be determined that the smaller the angle of the contact angle, the higher the hydrophilicity.

From the viewpoint that the permeability of the liquid is kept stable during use, and the surface flow and backflow of the liquid can be stably prevented for a long time during use, the fibers constituting the upper layer 21 have a contact angle of ion exchanged water before the liquid permeation. The contact angle of ion-exchanged water after 30-80 degrees, especially 40-70 degrees, and 50 g of ion-exchanged water permeate | transmitted in the circle of diameter 10mm, and drying at 30 degreeC for 2 hours is 35-80 degree In particular, it is preferable that they are 45 degrees-75 degrees.

From the same point of view, the fibers constituting the lower layer 22 have a total contact angle of 50 g of ion-exchanged water in a circle of 10 mm in diameter while the contact angle of the ion-exchanged water before liquid permeation is 60 ° or less, particularly 40 ° or less. It is preferable that the contact angle of ion-exchange water after making it permeate and dry at 30 degreeC for 2 hours is 40 degrees-100 degrees, especially 60 degrees-95 degrees. The lower limit of the contact angle before the liquid permeation of the fibers constituting the lower layer 22 is not particularly limited, but is 20 ° or more, in particular 25 ° in terms of liquid permeability at the initial stage, that is, smooth liquid transfer to the absorber. It is preferable that it is above.

As described above, the contact angle after permeation of the liquid is evaluated after permeation of 10 g of ion-exchanged water five times in a circle of 10 mm diameter. It is preferable that the upper layer 21 and the lower layer 22 have the contact angle.

(1) Measurement method of contact angle (initial contact angle) of ion-exchange water with respect to a constituent fiber.

Measurement was performed using a medium magnification zoom lens (with an illumination ring) lying down at 90 ° to the Micron Corporation VH-8000, and setting the conditions at 500 times. The sample for a measurement used what cut the surface sheet to the magnitude | size of MD 150 mm x CD 70 mm in the state which the upper and lower layers integrated. The measurement environment was 20 ° C./50% RH, and the sample for measurement was placed on the measurement stage so that the measurement surface was faced upward and the observation direction was observed in the CD direction of the web (nonwoven fabric).

The reason for observing the web in the CD direction is that in general, the fibers of the web are often oriented in the MD direction, and the possibility of the fibers being arranged in the width direction of the measurement screen increases. It arrange | positions in this way and observes with a lens in the direction perpendicular | vertical to the longitudinal direction of a fiber.

When obtaining the contact angle of the upper layer constituent fiber, the fiber of the upper layer surface is used as a measurement target, and when the contact angle of the lower layer constituent fiber is calculated | required, the fiber of the lower layer surface (surface of the side which contacts a absorber) is used as a measurement target. . Usually, in the multi-layered fiber sheet, it is possible to divide the sheet at the interface, but depending on the state of the interface, fibers of different layers may be mixed. For this reason, when the upper and lower layers have to be measured separately for some reason, the contact angle is measured from the surface not overlapping each other.

Subsequently, the placed sample for measurement was attached to the fiber surface with a sprayer filled with ion-exchanged water (using a tool that makes the spraying state as fine as possible) and burned within 5 seconds of attachment (to 2-3 seconds). To capture. The reason why image capturing is necessary for a short time after the attachment is to prevent the attached droplets from evaporating by the light emitted from the measuring section of the microscope and from causing a change in the contact angle due to an oil agent. As a result of clear observation of the focus of both ends or one end of the drop, 10 contact points were measured, and their average value was defined as "contact angle". The contact angle draws a tangent line with the fiber of water droplets, as shown in Figs. 8A and 8B, for the image or the printed photograph, and measures the result by image analysis or protractor. In addition, the measurement of a contact angle can also collect and measure each component fiber from the upper and lower layers instead of the surface sheet as it is.

On the other hand, the measurement of this contact angle needs to be performed paying attention to the following items.

(I) The contact angle in the upper surface of a fiber is measured. Drops placed on fibers are targeted and are not counted down to the bottom of the fiber, but over two or more fibers.

(II) When fibers produce fine crimps, such as spirals, they are measured in places where there are few crimps or by extending the fibers to eliminate crimps.

(III) The measurement result of the contact angle is the arithmetic mean of ten measured values which changed places, but when hydrophilicity is high, water droplets may hardly remain on the fiber during measurement. In that case, the "contact angle" is judged according to the flow rate.

ㆍ When less than 40% of the total number of measurements (the total number of measurement sites where the contact between the fiber and water is observed, the sum of the drop of water after contact and the flow of water that does not flow, the same is below) until the number of measurements reaches 10 , The average result of ten measured values is "contact angle".

• If more than 40% of the total number of measurements has flowed until 10 measurement values are reached, or if more than 40% has flown at the time of 10 measurements, the "contact angle" is set to 20 degrees or less.

(2) Measuring method of contact angle (contact angle after liquid permeation) of ion-exchange water with respect to the component fiber after liquid permeation.

The measurement was carried out in the same manner as in the method for measuring the contact angle before permeation of the liquid, except that the measurement sample was prepared as follows.

(Preparation of Sample for Measurement)

Paper which cut | disconnected the surface sheet to the magnitude | size of 150 mm x 70 mm, and adjusted it to the same magnitude | size as the surface sheet (paper which consists of pulp of basis weight 30g / m <^2> , crepe ratio 5-10%) It was piled up on 10 sheets and placed on the horizontal plane, and the acrylic plate with a cylinder shown in FIG. 5 was mounted on it. And the weight was put on the acryl plate, and the load of 10 g / cm <^2> was applied to the surface sheet. The size of the acrylic plate is 200 mm long x 100 mm wide x 8 mm thick, the height of the cylinder from the top of the acrylic plate is 50 mm, and the inner diameter of the cylinder is 22 mm from the top of the cylinder to 40 mm. In the range from the large diameter part to 5 mm downward, the inner diameter gradually decreased, and the small diameter part (height 5 mm) up to the lower end of the cylinder was 10 mm. The acrylic plate also had a coaxial hole having an inner diameter of 10 mm. As for the cylindrical inner surface between the large diameter part and the small diameter part, the cross-sectional shape by the plane containing a cylindrical axis was linear in each of the right and left sides of a cylindrical axis. The acrylic plate was placed so that the holes formed therein were located at the center of the surface sheet. In some cases, it is also possible to mark around the injection part in advance. On the other hand, when marking or the like is performed in advance, the marking means having no influence on the diffusion of the liquid is used, or the mark indicating the center of the MD / CD is applied to the measurement sample and the acrylic plate end to measure the measurement at the center crossing point. Do it.

Under this condition, ion-exchanged water is placed in a 10 mL beaker and slowly injected into the cylinder for 3 to 5 seconds. From the viewpoint of easy observation, the ion-exchange water used is colored by 0.3% of red No. 2 (external addition). The injection amount was 10 g and the entire amount was injected. After the implantation was completed and left for 30 seconds after the ion-exchanged water disappeared from the surface sheet surface, 10 sheets of paper were replaced with new ones and placed again in the same manner. When the paper is replaced, the weight, the acrylic plate, and the surface sheet are moved, but at this time, the acrylic plate and the surface sheet are kept from falling so that the ion-exchanged water can permeate through the same site. Then, ion exchanged water was injected again in the same manner. On the other hand, when ion-exchanged water does not disappear (liquid does not permeate) from the surface sheet surface even if it passes 180 second from the start of injection, it becomes impossible to measure and a contact angle is not measured.

After repeating these operations and injecting 50 g (5 times) of ion-exchanged water in total, the weight and acrylic plate were removed, and the surface sheet after removing the paper was removed using a DSR-114S (manufactured by ISUZU) electric dryer. It dried at 2 degreeC for 2 hours, and made it the sample for measurement of the surface sheet after liquid permeation. In addition, a contact angle is measured about the component fiber of the part (in-circle) which permeate | transmitted the ion-exchange water of this sample for a measurement.

On the other hand, the contact angle of ion-exchanged water after permeating 100 g of ion-exchanged water in a 10 mm-diameter circle, and drying at 30 degreeC for 2 hours changes the 10g ion-exchanged water 5 times to 10 times, and repeats. In addition, it can measure similarly to the measuring method of the contact angle of ion-exchange water with respect to the component fiber after liquid permeation mentioned above.

The surface sheet initially has a higher Klemm absorption in the lower layer than the upper layer, and it is preferable that the Klem absorption of the upper layer part is 20 mm or more after 3 minutes, and more preferably, after 3 minutes. , 30 mm or more. It is preferable that the clem absorption degree of a lower layer part is 35 mm or more after 3 minutes, More preferably, it is 40 mm or more after 3 minutes. The height of the hydrophilicity of the upper layer and the lower layer before the liquid permeation can also be determined by the clem absorption degree.

(3) Method of measuring clem absorbance.

In the measurement of the clem absorption of the upper part and the lower part, after separating the upper layer and the lower layer so that there is no damage, each part is measured independently. For the measurement, the height from the water surface three minutes after the placement was used as ion-exchange water colored with 0.3% red No. 2 (external), and the clem absorption degree. On the other hand, although the clem absorbance is performed according to JIS P8141 (1996) "A water absorption test method by the clem method of paper and paperboard", the measurement direction measures only the MD direction.

In addition, the height of the hydrophilicity of the upper layer and the lower layer after liquid permeation can be judged using the liquid passage time of ion-exchange water as an index. Specifically, a liquid permeation method (method of injecting ion exchanged water), which is the same as the "(2) measuring method of contact angle of ion exchanged water to the constituent fiber after liquid permeation (contact angle after liquid permeation)," is used. After permeation of 10 g of ion-exchanged water in a 1 mm circle, the time until the liquid permeate when 10 g of ion-exchanged water is further injected after drying is determined as the passage time of the liquid. . The liquid passing time is a thing with a short liquid passing rate and a high hydrophilicity.

As for the liquid passage time, the upper layer is preferably shorter than the lower layer. From the viewpoint of the permeability of the liquid by maintaining the hydrophilicity after the liquid permeation, the upper liquid passage time (after having once permeated ion-exchanged water) is preferably 40 seconds or less for the second injection, and 30 seconds or less. Is more preferable, and 20 second or less is further more preferable. In addition, from the viewpoint of the persistence of the hydrophilicity, the second injection of the upper layer is preferably 60 seconds or less, more preferably 40 seconds or less. The lower liquid passage time (after having once permeated the ion-exchanged water) is preferably 80 seconds or more and more preferably 90 seconds or more for the second injection from the viewpoint of preventing backflow and the transfer of the liquid to the absorber. Do. In addition, from the same viewpoint, the second injection is preferably 90 seconds or more, more preferably 120 seconds or more.

In addition, the difference between the liquid passage and the time between the upper layer and the lower layer is preferably 30 seconds or more, more preferably 50 seconds or more for the second injection, from the viewpoint of the transferability of the liquid from the upper layer to the lower layer and the prevention of backflow. From the same viewpoint, the second injection is preferably 90 seconds or more, more preferably 120 seconds or more.

About a liquid permeation time, a measuring method is shown below.

(4) Measurement of liquid passage time

The liquid passage and velocity test are carried out in the same manner as described above except for (2) measuring method of contact angle of the ion-exchanged water with respect to the constituent fiber after liquid permeation (contact angle after liquid permeation) and some procedures with the sample. Only the other points are shown below.

Measurement sample: The upper layer and the lower layer of the surface sheet are measured separately. Although the upper layer and lower layer of a surface sheet are peeled off at the interface, and a measurement is performed, you may create and measure a new upper layer and a lower layer separately.

Evaluation procedure: 10 g of ion-exchanged water was injected in the same manner as in (2) above, and the time until the ion-exchanged water disappeared from the surface of the time measurement sample (upper or lower sample of the surface sheet) with the start of injection ( Fluid passage time). After injection and permeation of ion-exchanged water once, the measurement sample is dried at 30 ° C. for 2 hours, and the second injection and the liquid passage time are measured for the same site. Similarly, drying after liquid permeation is repeated and liquid permeation is performed 5 times. On the other hand, the measurement sample dried after one transmission may measure the contact angle at the permeation site, but the measurement may be the same sample, or may be another measurement sample which has been subjected to liquid permeation and drying in the same manner. Even if 180 seconds have elapsed since the start of injection of the ion exchanged water, when the ion exchanged water does not disappear from the surface of the measurement sample (the liquid does not penetrate), the liquid passage time is 180 seconds or more, and the measurement of the contact angle and the next liquid passage time Is not measured.

The upper layer 21 and the lower layer 22 of the surface sheet 2 are all made of hydrophobic fibers hydrophilized with a hydrophilic agent.

As a method of hydrophilizing a hydrophobic fiber with a hydrophilic agent, a method of treating the fiber before formation of the fiber aggregate with a hydrophilic agent (immersion (dipping method), spraying, gravure coating, printing, etc.), and a hydrophilic agent over a resin for forming a fiber And a method of bleeding out and treating the fiber aggregate after forming the fiber aggregate with a hydrophilic agent, but the dipping method of treating the fiber before forming the fiber aggregate with a hydrophilic agent stably provides hydrophilicity. It is preferable from the viewpoint of the processability oil agent (for friction reduction at the time of web formation by a card method) which is needed when expressing and nonwoven fabricizing a fiber.

The hydrophilicity of the lower layer is higher than that of the upper layer before the liquid permeation, and the combination of the upper layer and the lower layer in which the high and low relations of the hydrophilicity reverses after the large amount of ion-exchanged water permeates the hydrophobic fibers and the respective fibers used for the upper layer and the lower layer. It can achieve by selecting suitably the hydrophilic oil agent used for hydrophilization.

As the hydrophobic fiber used for the upper layer 21, polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, vinyl resins such as polyvinyl chloride, polyamide resins such as nylon and the like are used. do. In addition, among the above various raw materials, composite fibers (sheath-core conjugate fibers or side-by-side conjugate fibers) composed of a combination of two kinds of resins may be used. have. Among these, particularly preferable fibers are polyester resins such as polypropylene (polyolefin resin) and polyethylene terephthalate, and a sheath type using polypropylene or polyester in a core component and polyethylene in a sheath component. It is a composite fiber.

As the hydrophilic agent used for the constituent fibers of the upper layer 21, those having various molecular weights of anionic, cationic, amphoteric and nonionic surfactants can be used alone or in combination, but among these, many nonionic surfactants are used. It is preferable to mix | blend in the point which the functional stability by adhesion bond to a fiber surface and the similar bond between surfactant molecules is small, and especially high molecular weight is more preferable at the point which acquires durability. Moreover, as a means of making it easy to fix a hydrophilic oil agent to a fiber surface, it is also preferable to use a means, such as a fixing agent and a cut-in, from a point of durability improvement.

It is preferable that content in the upper layer 21 of the hydrophobic fiber hydrophilized by the hydrophilic agent is 50-100%, especially 80-100% in the total mass of the upper layer 21. The amount of adhesion of the hydrophilic oil agent is preferably 0.2 to 1.0% by mass of the hydrophobic fiber from the viewpoint of stably expressing the hydrophilicity on the surface of the fiber and preventing the deterioration of the texture such as stickiness.

As the hydrophobic fiber used for the lower layer 22, the same fiber as the hydrophobic fiber used for the upper layer 21 can be used, but a particularly preferable fiber is a core sheath composite fiber or a side-by-side composite fiber.

In addition, as a hydrophilic oil agent used for the constituent fiber of the lower layer 22, although the thing of various molecular weights of anionic, cationic, amphoteric, and nonionic surfactant can be used individually or in combination, Among these, cationic surfactant is used. It is preferable to mix | blend a lot with a high hydrophilicity of an initial stage, and a suitable durability is obtained.

It is preferable that content in the lower layer 22 of the hydrophobic fiber hydrophilized with the hydrophilic oil agent is 50 to 100%, especially 80 to 100% in the total mass of the lower layer 22. In addition, the amount of adhesion of the hydrophilic agent to the hydrophobic fiber is 0.2 to 1.0% by mass, thereby stably expressing the hydrophilicity on the surface of the fiber, thereby reducing the workability (degradation of the bonding by the thermal / adhesive agent by contaminating the surface of the absorber with the hydrophilic oil). Etc.) is preferable from the viewpoint of preventing.

As a manufacturing method of the laminated nonwoven fabric which consists of the upper layer 21 and the lower layer 22, after laminating | stacking two nonwoven fabrics manufactured by the same or another manufacturing method, a heat sealing, an ultrasonic chamber, an adhesive agent And the like are partially bonded to each other in the thickness direction, and the fibers are deposited on nonwoven fabrics produced by various manufacturing methods, followed by heat fusion treatment by air through or heat embossing, and water. Fibrous webs produced by a method of integrating, or integrating, fibers of the deposited fiber portions and the deposited fibers and the fibers of the nonwoven fabric by integrating treatment such as needling, carding machines, and the like. The two sheets are piled up, and the method of performing an integrated process as mentioned above to this is mentioned.

Examples of the nonwoven fabric used for forming the upper layer 21 and / or the lower layer 22 include a nonwoven fabric formed by a thermal fusion method, a nonwoven fabric formed by a water flow method, and a needle punched method. The nonwoven fabric, the nonwoven fabric formed by the solvent bonding method, the nonwoven fabric formed by the spunbond method, the nonwoven fabric formed by the meltblown method, etc. are mentioned.

On the other hand, for adjustment of the hydrophilicity, the upper layer and the lower layer may contain hydrophilic fibers such as rayon and cotton whose material itself is hydrophilic even without hydrophilization treatment. However, it is preferable that content in the case of containing such a hydrophilic fiber is 30% or less in an upper layer, and 70% or less in a lower layer.

In the present invention, it is preferable that the apparent density of the lower layer 22 is higher than the apparent density of the upper layer 21 from the viewpoint of further improving the transferability of the liquid from the upper layer to the lower layer.

As a method of making the apparent density of the lower layer 22 higher than the upper layer 21, the fineness of the fiber which comprises the lower layer 22 is made larger than the fineness of the fiber which comprises the upper layer 21, and / or The method of making the interfiber distance of the fiber which comprises the lower layer 22 smaller than the interfiber distance of the fiber which comprises the upper layer 21 can be used.

The apparent density of the lower layer 22 and the apparent density of the upper layer 21 can be measured as follows.

After peeling the upper layer and the lower layer, a plate (or a plate on which weight is adjusted) is adjusted to have a load of 0.5 g / cm 2, and the thickness is observed (the thickness is observed at any one of the MD / CD ends). , Adjust the plates so that the load is at the MD / CD end). For observation, the microscope VH-8000 made by KEYENS is used with the medium magnification zoom lens (with an illumination ring) laid at 90 ° at low magnification. The apparent density is calculated by substituting the obtained thickness value into the following equation.

Appearance Density (g / cm 3) = [Basic weight (g / m 2) / thickness (mm) of nonwoven fabric] × 10 ³

The apparent density of the lower layer 22 is preferably 0.05 to 0.5 g / cm 3 from the viewpoint of improving the penetration of the initial liquid, and the apparent density of the upper layer 21 makes it easier to move the liquid to the skin texture and the lower layer. It is preferable that it is 0.01-0.3 g / cm <3> from a viewpoint.

As a material which comprises each part of the sanitary napkin 1, what is normally used in the said technical field can be used without a restriction | limiting in particular. For example, as the back sheet 3, a liquid impermeable film is preferably used. As the absorber 4, a mixed laminate of fluff pulp and superabsorbent polymer particles, or a wrapper with a liquid permeable sheet such as tissue paper can be used. As the side part forming sheet 5, a water repellent nonwoven fabric, a liquid impermeable resin film, or the like can be used.

As mentioned above, although preferred embodiment of this invention was described, this invention can be suitably changed in the range which does not deviate from the meaning.

For example, although the upper layer 21 and the lower layer 22 may each have a planar shape, as shown in FIG. 6 or FIG. 7, at least the upper layer 21 has irregularities on the surface of the liquid remaining on the surface. It is preferable from the viewpoint of prevention, improvement of dry feeling, and the like. In the example shown in FIG. 6, the upper layer 21 and the lower layer 22 are partially heat-sealed by the heat embossing process, and parts other than the heat-fusion part 23 of the upper layer 21 are the skin of a wearer. The convex part 24 which protrudes toward the side is formed, and the said heat-sealed part 23 forms the recessed part. In the example shown in FIG. 7, the three-dimensional opening 26 which penetrates the upper layer 21 and the lower layer 22, and the opening periphery 25 protrudes toward the lower layer 22 is formed. It is. The surface sheet of FIG. 7 inserts between the press roll which has many perforation pin in the main surface, and the support roll which has many support holes into which a perforation pin is inserted, and a three-dimensional opening ( The upper layer 21 and the lower layer 22 are integrated by the heating and pressurization at the time of forming the 26.

In addition, as for the sanitary napkin (absorbent article) in the said embodiment, only the center area | region in the width direction of a napkin is coat | covered by the above-mentioned surface sheet 2, The whole area | region of the surface by the skin contact surface side of an absorber is mentioned above. It may be coat | covered on one surface sheet 2, and only the center part of the longitudinal direction and the width direction of a sanitary napkin may be coat | covered at the surface sheet 2 mentioned above.

In addition to the sanitary napkin, the absorbent article of the present invention may be a incontinence pad, a panty liner, a disposable diaper, or the like.

Hereinafter, the present invention will be further described using examples. However, the scope of the present invention is not limited to this embodiment.

[Example]

The surface sheet used in the Example is nonwoven fabric by the following fiber and a manufacturing method.

(Use fiber)

After the fiber is dipped in an aqueous solution in which the hydrophilic emulsion component is dissolved, a predetermined amount of hydrophilic emulsion component adheres to the fiber surface through a drying step (so-called dipping method). Here, the hydrophilic oil agent also includes various processability components (for example, a friction reduction target component at the carding step) which are necessary for the production of the nonwoven fabric. In addition, the quantity (concentration) of the hydrophilic emulsion component melt | dissolved in the said aqueous solution is calculated from the component amount of the hydrophilic emulsion which should adhere to the fiber surface rather than the quantity of the aqueous solution which each fiber holds.

Fiber A; 0.45 mass% of hydrophilic fiber-oil agents a adhere | attach with respect to the fiber A to Daiwa Boseki Co., Ltd. product NBF (SH) 2.2 dtex x 51 mm (core component PET / second component PE, volume ratio 1: 1).

Fiber B; 0.45 mass% of hydrophilic fiber-oil agents a adhere | attach with respect to the fiber B to Daiwa Boseki Co., Ltd. product NBF (SH) 3.3 dtex x 51 mm (core component PET / second component PE, volume ratio 1: 1).

Fiber C; 0.3 mass% of hydrophilic fiber oil agents b adhere | attach with respect to the fiber C to Daiwa Boseki Co., Ltd. product NBF (SH) 2.2 dtex x 51 mm (core component PET / second component PE, volume ratio 1: 1).

Fiber D; 0.35 mass% of hydrophilic fiber emulsions c are affixed to the fiber D in Daiwa Boseki Co., Ltd. product NBF (SH) 2.2 dtex x 51 mm (core component PET / second component PE, volume ratio 1: 1).

Fiber E; 0.3 mass% of hydrophilic fiber oil agents d adhere to the fiber E in Daiwa Boseki Co., Ltd. product NBF (SH) 2.2 dtex x 51 mm (core component PET / second component PE, volume ratio 1: 1).

Fiber F; 0.35 mass% of hydrophilic fiber emulsions e are affixed to the fiber F in Daiwa Boseki Co., Ltd. product NBF (SH) 2.2 dtex x 51 mm (core component PET / second component PE, volume ratio 1: 1).

Fiber G; The hydrophilic fiber oil f is 0.42 mass% with respect to the fiber G in Daiwa Boseki Co., Ltd. product NBF (SH) 2.2 dtex x 51 mm (core component PET / second component PE, volume ratio 1: 1).

The hydrophilic fiber emulsion used for the said fiber is respectively the following composition, and all except active ingredients are moisture.

Hydrophilic fiber emulsion a (active ingredient 25%): 20% POE fatty acid amide / alkylphosphoric ester potassium salt 20% / alkyl betaine 30% / alkyl sulfosuccinate Na salt (sodium alkylsulfosuccinate) 30 %

Hydrophilic fiber emulsion b (active ingredient rate 40%): Alkyl phosphate ester K salt 70% / alkyl glycol 30%

Hydrophilic fiber emulsion c (active ingredient rate 55%): 60% alkyl alcohol phosphate K salt / 40% alkyl phosphate K salt

Hydrophilic fiber emulsion d (active ingredient rate 50%): polyoxyethylene alkyl ether sulfate ester Na salt 50% / fatty acid Na salt 50%

Hydrophilic fiber emulsion e (active ingredient rate 35%): alkyl phosphate ester K salt 60% / alkyl glycol 30% / modified silicone 10%

Hydrophilic fiber emulsion f (active ingredient rate 30%): 20% POE fatty acid amide / alkyl phosphate ester K salt 20% / alkyl betaine 30% / alkyl sulfosuccinate Na salt 30%

(Making of nonwoven fabric)

Example 1: Fiber A was broken down by a carding machine to form a web having a basis weight of 12 g / m 2, and Fiber D was broken down by a carding machine to create a web having a basis weight of 13 g / m 2, and both webs were folded together. Then, it was set as the nonwoven fabric of basis weight 25g / m <2> by hot air (air through method) of 136 degreeC.

Example 2: Fiber B was cut out by a carding machine to produce a web having a basis weight of 12 g / m 2, and Fiber C was cut out by a carding machine to create a web having a basis weight of 13 g / m 2, and both webs were stacked together, and then 136 ° C. It was set as the nonwoven fabric of basis weight 25g / m <2> by hot air (air-through method) of.

Example 3: Fiber A was cut into a carding machine to prepare a web having a basis weight of 25 g / m 2, and a nonwoven fabric was made by hot air at 136 ° C. (air through method), and fiber C was cut into a carding machine to cut a basis weight of 25 g / m 2. After setting it as the nonwoven fabric of the fiber A, it piled up and integrated with the pin embossing roll (embossing method) of 130 degreeC, and made it the nonwoven fabric of 50 g / m <2> of basis weight.

Example 4 Fiber A was cut with a carding machine to form a web having a basis weight of 25 g / m 2, and a nonwoven fabric was made by hot air at 136 ° C. (air through method). The web is made of a nonwoven fabric by hot air at 136 ° C. (air-through method), and the two nonwoven fabrics are wrapped with each other, followed by a pin roll heated at 130 ° C., and a thin plate inserted between the pins and the pins. The nonwoven fabrics piled with each other were passed between the supporting rolls heated to 0 ° C. to form pores and, at the same time, integrated at the end of the openings to form a nonwoven fabric having a basis weight of 50 g / m 2 (method of Japanese Patent Laid-Open No. 10-80445). ).

Example 5 Fiber G was cut out by a carding machine to form a web having a basis weight of 25 g / m 2, and a nonwoven fabric was made by hot air at 136 ° C. (air through method), and fiber E was cut out by a carding machine to have a basis weight of 25 g / m 2. After setting it as the nonwoven fabric of the fiber G, it piled up and integrated with the pin embossing roll (embossing method) of 130 degreeC, and made it the nonwoven fabric of 50 g / m <2> of basis weight.

Comparative Example 1: A nonwoven fabric was produced in the same manner as in Example 1 except that Fiber D was used instead of Fiber A.

Comparative Example 2: A nonwoven fabric was produced in the same manner as in Example 3 except that Fiber F and Fiber C were used instead of Fiber A.

Comparative Example 3: A nonwoven fabric was produced in the same manner as in Example 3 except that Fiber F and Fiber C were used instead of Fiber A.

Comparative Example 4: A nonwoven fabric was produced in the same manner as in Example 1 except that Fiber D was used instead of Fiber A and Fiber A was used instead of Fiber D.

Each nonwoven fabric of an Example and a comparative example manufactured several sheets of the same structure, respectively, and used the different nonwoven fabric (the structure is the same) for every measurement in the measurement of following (a)-(d).

(a) Measurement of initial contact angle

About each obtained nonwoven fabric, the contact angle of the component fiber of an upper layer and a lower layer was measured by measuring the front side and the back side of each nonwoven fabric, respectively. The measuring method is the same as the measuring method of (1) initial contact angle mentioned above. The measurement result was shown in the column of contact angle "initial stage" of Table 1.

(b) Measurement of contact angle after liquid permeation

According to the measuring method of the contact angle after permeation of (2) liquid, 50 g of ion-exchange water was permeate | transmitted in the circle of diameter 10mm in each nonwoven fabric, and then dried. The contact angles of the constituent fibers of the upper layer and the lower layer were measured with respect to the ion-exchange water permeable part (in the circle) in each nonwoven fabric. The measurement result was shown in the column of the contact angle "after 50g liquid passage" of Table 1. Next, about some nonwoven fabric which was measurable (liquid permeation time of 180 s or less), 100 g of ion-exchange water was permeated to the newly adjusted nonwoven fabric, and it was then dried. Similarly, the contact angle was measured and the measurement result was shown in the column of the contact angle "after 100 g liquid passage" of Table 1. In addition, in the contact angle evaluation after liquid permeation, when the measurement (liquid passage time of 10 g of ion-exchange water) for one liquid permeation exceeded 180 second, measurement was made into impossible and measurement was complete | finished.

(c) Measurement of liquid bottle time and repeated contact angle

The measurement of the liquid passage and the speed test and repeat contact angle described in Table 2 is as shown in the above (4) measurement of the liquid passage time. As the measurement sample, the upper layer of Example 3, the upper layer of Example 2, the lower layer of Example 2, the upper layer of Comparative Example 1, and Comparative Example 2 and the lower layer of Comparative Example 2 were used.

When only the upper layer or the lower layer of the integrated nonwoven fabric is used for the measurement, the surface different from the peeling surface of the upper layer and the lower layer must be used as the measurement surface. On the other hand, the contact angle in the case where the liquid passage time exceeded 180 second was not measured without measuring.

(d) Liquid surface diffusion evaluation

On the plate inclined at 45 °, each nonwoven fabric was fixed with the lower layer facing the plate side, and on the nonwoven fabric, 0.3% of red No. 2 at a rate of 1 g / 10 seconds from a silicon tube having an inner diameter (Φ) of 5 mm. Ion-exchange water colored by (external) was dripped for 30 second, and the distance of the liquid which flowed through the upper layer was measured. In this evaluation, the state which flows between the upper layer and the lower layer (until the state in which less than half of the droplets appear on the surface) is not considered to flow through the surface layer.

According to the surface sheet of the absorbent article of the present invention, the permeability of the liquid can be stably maintained during use of the absorbent article, and the surface flow or wet back of the liquid can be prevented for a long time during use.

According to the absorbent article of the present invention, the permeability of the liquid of the surface sheet is kept stable during use, and the surface flow and reverse movement of the liquid can be prevented for a long time during use.

Claims (6)

It consists of a laminated nonwoven fabric having an upper layer disposed on the skin side and a lower layer disposed on the absorber side, The fiber constituting the upper layer had a contact angle of ion exchanged water before the liquid permeation was 30 ° to 80 °, permeated 10 g of ion exchanged water five times in a 10 mm diameter circle, and dried at 30 ° C for 2 hours. The contact angle of ion-exchange water in the said inside of said circle is 35-80 degrees, The fiber constituting the lower layer has a contact angle of ion exchanged water of 20 ° or more and 60 ° or less before the liquid permeation, and allows 10 g of ion exchanged water to permeate five times in a circle having a diameter of 10 mm, and at 30 ° C. for 2 hours. The contact angle of ion-exchanged water in the said circle after drying is 40 degrees-100 degrees, Before the liquid permeation, the hydrophilicity of the lower layer is higher than or substantially the same as that of the upper layer, and after the liquid permeation, the hydrophilicity of the upper layer is higher than the lower layer. delete delete The method of claim 1, The apparent density of the lower layer is 0.05 to 0.5 g / cm 3, the apparent density of the upper layer is 0.01 to 0.3 g / cm 3, and the apparent density of the lower layer is higher than the apparent density of the upper layer. . An absorbent article comprising the surface sheet according to claim 1, a liquid-impermeable back sheet, and a liquid-retaining absorber interposed between these two sheets. delete

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