JP7049794B2 - Menstrual napkin - Google Patents

Description

The present invention relates to a menstrual napkin that absorbs and retains menstrual blood and prevents leakage to the back surface. In particular, a non-woven fabric is used for the liquid-permeable surface sheet, and surface embossing is formed on the liquid-permeable surface sheet. Regarding menstrual napkins that have been made.

Conventionally, as a menstrual napkin, an absorbent material made of cotton-like pulp or the like is interposed between an impermeable back sheet made of a polyethylene sheet or a polyethylene laminated non-woven fabric and a liquid-permeable front sheet made of a non-woven fabric. It has been known.

An important function required of the liquid-permeable surface sheet is to quickly inhale the body fluid so that the body fluid does not come into contact with the skin for a long period of time, allow the body fluid to be absorbed by the absorber, and prevent the once absorbed body fluid from reversing. In other words, it is responsible for the permeability of the liquid and the function of suppressing liquid return and liquid residue. Further, since it is a part that comes into direct contact with the skin, it is required to have less irritation to the skin and to have a good touch.

When using a menstrual napkin, the inside becomes a humid environment, but if the body fluid is not removed from the skin surface when the body fluid is discharged, it is thought that it may lead to user discomfort such as stuffiness and stickiness. In addition, the vulva to which the menstrual napkin comes into contact is thinner than the torso and limbs, with the thickness of the horny layer being about 1/3 to 1/2. Since the keratin has a role of protecting the skin from external bacteria and irritation, it can be said that the vulva has a relatively low barrier function of the skin. As a means to solve these problems, the former problem is effective in reducing the humidity near the skin by increasing the liquid permeability of the non-woven fabric, and the latter problem is effective in reducing the friction between the liquid permeable topsheet and the skin. It becomes.

On the other hand, the liquid-permeable surface sheet may be embossed from the surface side for the purpose of controlling the diffusion region of the body fluid and reducing the surface residue of menstrual blood and cages. For example, in Patent Document 1 below, in an absorbent article having a liquid-permeable surface material layer, a liquid-impermeable back surface material layer, and an absorber arranged between the two material layers, the absorber is The width dimension is narrower than that of the front surface material layer and the back surface material layer, and the side edge portion extending in the longitudinal direction of the absorber is located inside the side edge portion of the front surface material layer and the back surface material layer. When the region where the absorber is provided is the central region and the side edge portion of the absorber and the side edge portion of the front surface material layer and the back surface material layer are the side region, both sides of the central region are defined. Embossed compression portions in which only the surface material layer is compressed are formed in the portions continuously in the longitudinal direction or arranged in the longitudinal direction, and the embossed compression portions are formed in each of the absorbers. Disclosed are absorbent articles formed in a width dimension extending from the central region to the side region across the side edges of the body.

Further, in Patent Document 2 below, in an absorbent article in which an absorber is interposed between a liquid-permeable front sheet and a back surface sheet, the liquid-permeable surface sheet is made of a non-woven fabric, and the liquid-permeable surface sheet and the liquid-permeable surface sheet and the like. The liquid-permeable front sheet extends outward from the edge of the back sheet, at least at the front and rear ends of the absorbent article in the outer peripheral flap portion in which the back sheet extends outward from the edge of the absorber. A plurality of squeezing grooves arranged along the substantially longitudinal direction of the absorbent article and at intervals in the width direction of the absorbent article in a plan view are provided on the liquid-permeable surface sheet. The squeezing groove is provided and absorbs a first wavy pattern in which a protruding portion toward one side and a protruding portion toward the other side are alternately repeated in the width direction of the absorbent article, and the first wavy pattern. The second wavy pattern inverted in the width direction of the article is formed by a wavy pattern in which the second wavy pattern is alternately arranged in the width direction of the absorbent article, and the squeezing is performed at least at the front and rear ends of the absorbent article in the outer extending portion. An absorbent article in which a wavy pattern of grooves is formed for one cycle or more is disclosed.

Japanese Patent No. 4278963 Japanese Patent No. 5972584

As mentioned above, the effect of embossing on the liquid-permeable surface sheet has been confirmed to control the diffusion area of body fluid and reduce menstrual blood and the surface residue of the cage. As clarified in the preliminary experiment>, when the non-woven fabric is embossed, the friction coefficient is reduced in the low contact pressure state (0.49 kPa) such as when standing up compared to the non-embossed non-woven fabric. However, in a high contact pressure state (1.6 kPa) such as when sitting, the coefficient of friction increases compared to the non-embossed non-woven fabric due to the increase in the "true contact area" based on the friction adhesion theory described later. It turned out to be highly fearful.

The specimen used in the <preliminary experiment> is a non-woven fabric having any specific physical characteristics, but as described above, the vulva to which the menstrual napkin comes into contact has a thickness of 1/3 to 1/3 of the keratin of the body and limbs. Since it is as thin as about 1/2, it is desirable to avoid increasing the coefficient of friction as much as possible considering the effect on the skin.

Therefore, the main problem of the present invention is that the coefficient of friction of the embossed region is not embossed both when standing (0.49 kPa) and when sitting (1.6 kPa) while using the embossed liquid-permeable surface sheet. The purpose is to avoid skin troubles as much as possible by keeping the coefficient of friction or less in the applied region.

In order to solve the above-mentioned problems, as the present invention according to claim 1, in a menstrual napkin in which an absorber is interposed between a liquid-permeable front sheet and a back sheet.
As the liquid-permeable surface sheet, a non-woven fabric is used, and at least on the surface side to be used with respect to the non-woven fabric, in a plan view, along the longitudinal direction of the menstrual pad, a protrusion toward one side in the width direction of the napkin. The first wavy pattern in which the portion and the protruding portion to the other side are alternately repeated and the second wavy pattern in which the first wavy pattern is inverted in the napkin width direction are alternately arranged in the napkin width direction. The surface embossing is formed in a wavy pattern, the depth of the surface embossing is 400 μm or more and 700 μm or less, and the surface embossing is formed in the intermediate portion in the longitudinal direction including the body fluid discharge portion of the liquid permeable surface sheet. An embossed region including a portion is arranged, and an embossed unembossed region without the surface embossing is arranged at the front and rear ends of the liquid permeable surface sheet.
The liquid-permeable surface sheet is a non-woven fabric having a two-layer structure composed of an upper layer and a lower layer, and constitutes a surface non-woven fabric in which the upper layer comes into contact with the skin . A crimped fiber made of short fibers having a thickness of 2.2 dt or more and 3.0 dt or less using a sheath-type fiber, and the lower layer is an eccentric core-sheath-type fiber having a core of polyethylene terephthalate and a sheath of polyethylene. A non-woven fabric is used, which consists of short fibers with a thickness of 4.0 dt or more and 7.0 dt or less, and the upper layer has a weight ratio of 40% or less of the whole.
The coefficient of friction of the liquid-permeable surface sheet was measured by the following slip friction test method for the embossed region including the portion where the surface emboss was formed and the non-embossed region where the surface emboss was not applied. When
The measured value in the vertical pressure load state of 0.49 kPa assuming the standing position shows that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the non-embossed region.
Provided is a sanitary napkin characterized in that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the non-embossed region even in the measured value under a vertical pressure load state of 1.6 kPa assuming the time of sitting. ..
(Slip friction test method)
(1) Perform a friction test using a direct-acting slip friction tester (Trinity Lab Co., Ltd. Speed Fluctuation Friction Tester Type: μv-1000).
(2) Using an artificial skin piece made of polyurethane that imitates human skin, attach the artificial skin piece to the lower part of the load cell, fix the non-woven fabric sample on the stage, and bring the artificial skin piece into contact.
(3) The vertical load is applied by a weight on the upper part of the load cell so that it is equivalent to the apparent contact pressure (standing: 0.49 kPa, sitting: 1.6 kPa) applied to the attached napkin when standing and sitting. A slip friction test is performed by applying a load and reciprocating the stage.
(4) The test shall be conducted under a slip speed of 1 mm / s, a slip distance of 5 mm, a friction repetition rate of 10 times, and no lubrication in the atmosphere.
(5) The slip direction is the machine direction, which is the flow direction of the fibers of the non-woven fabric, and the test is repeated three times under the same conditions in order to obtain reproducibility.
(6) The average value of the friction coefficient in the period corresponding to 10 to 90% of the slip time in the 10th repetition is used as the friction coefficient.

In the invention according to claim 1, a liquid-permeable surface sheet made of a non-woven fabric having a surface embossed in an arbitrary pattern on at least the surface side to be used is used. The liquid-permeable surface sheet uses fibers having a fiber diameter of 2.2 dt or more and 3.0 dt or less as constituent fibers of the non-woven fabric of the surface layer that comes into contact with the skin. As shown in Test>, the friction coefficient of the embossed region can be set to be equal to or less than the friction coefficient of the non-embossed region both when standing (0.49 kPa) and when sitting (1.6 kPa).

With respect to the fiber diameter, the friction coefficient of the embossed region is equal to or less than the friction coefficient of the embossed region in both standing (0.49 kPa) and sitting (1.6 kPa) with the lower limit value "2.2 dt or more" as the boundary value. Can be. In addition, regarding the upper limit of "3.0 dt or less", if the fiber diameter is increased too much, the voids between the fibers will increase, and although the liquid permeability will improve, problems such as reversion are likely to occur, so this type of menstrual napkin As the surface sheet 3 of the above, the numerical value on the upper limit side that can be generally taken was used.

In general, when discussing the friction of a substance, there are various models such as the unevenness theory, the adhesion theory, the digging theory, and the junction-growth model of the friction model. Apply it to the model of the theory.

The details will be described later, but according to the adhesion theory, in the case of an embossed surface material, the side surface of the embossing has a relatively dense structure because the surrounding fibers enter during the embossing. There is. When the load is low (0.49 kPa) such as when standing, the side surface of the emboss does not deform significantly even if the load is applied, and the bottom of the emboss is maintained in a state where it is not in contact with the skin. At times (0.49 kPa), the coefficient of friction is reduced compared to the surface of the non-embossed non-woven fabric.

On the other hand, when the load is high (1.6 kPa) such as when sitting, the embossed side surface cannot bear the load, the embossed bottom comes into contact with the skin, and the fibers are densely present on the embossed side surface. Therefore, it is considered that the contact area tends to increase and the true contact area tends to increase.

Therefore, in the present invention, as a result of diligent research on what kind of non-woven fabric structure should be used to prevent the contact area with the skin from increasing when seated (1.6 kPa), the non-woven fabric receives cushioning properties, compression followability, and compressive force. As a result of finding that it is effective to improve physical properties such as deformation resistance at the time of occurrence, we have focused on the fiber diameter of the non-woven fabric.

In the present invention, in particular, fibers having a fiber diameter of 2.2 dt or more and 3.0 dt or less are used as constituent fibers of the nonwoven fabric, so as to improve the cushioning property, compression followability, and deformation resistance of the nonwoven fabric when subjected to compressive force. I made it. As a result, even under a high load (1.6 kPa) such as when sitting, the side surface of the emboss does not deform significantly even when the load is applied, and the bottom of the emboss is maintained in a state where it is not in contact with the skin. Even when seated (1.6 kPa), the coefficient of friction in the embossed region can now be less than or equal to the coefficient of friction in the non-embossed region.

Further, in the invention according to claim 1, a suitable example of the liquid permeable surface sheet is shown more specifically. In particular, in the upper layer, a core-sheath type fiber having polyethylene terephthalate as a core material is used. Polyethylene terephthalate has relatively higher shape stability than polyolefin-based fibers, and can improve cushioning property, compression followability, and deformation resistance when subjected to compressive force.

Further , the invention according to claim 1 defines a region where surface embossing is formed. By forming surface embossing at least in the region including the body fluid draining site, it is possible to quickly diffuse the body fluid discharged to the body fluid draining site in the longitudinal direction in the region including the body fluid draining site, and the genital area is formed. The horny layer is thinner than the body and limbs, and by applying the embossed area that reduces friction to the genital area, skin troubles can be alleviated as much as possible.

It should be noted that the present invention does not exclude the formation of the surface embossing over the entire surface sheet. In this case, the friction coefficient of the non-embossed region where the surface embossing is not applied may be measured by measuring the friction coefficient in the region where the embossing between the embossing and the embossing is not formed. When the measurement target area is narrow, it can be dealt with by reducing the area of the artificial skin piece of the slip friction test device or reducing the slip distance. The present invention has an embossed region including a portion where surface embossing is formed and surface embossing in a vertical pressure load state of 0.49 kPa assuming standing and a vertical pressure load state of 1.6 kPa assuming sitting. Since the magnitude relationship of the coefficient of friction with the unembossed region to which is not applied is specified, no problem occurs even if the measurement conditions are arbitrarily changed slightly. In particular, it is considered that the friction coefficient of the unembossed region can be measured even in a very small area.

Further, the invention according to claim 1 shows a specific example of an arrangement pattern of a surface embossed region. Specifically, the body fluid discharged to the body fluid discharge portion is provided by arranging the embossing region including the portion where the surface embossing is formed in the longitudinal intermediate portion including the body fluid discharge portion of the liquid-permeable surface sheet. Is quickly diffused, and the front and rear ends in the longitudinal direction are set to the non-embossed region to suppress the diffusion, and in the intermediate portion in the longitudinal direction including the body fluid discharge site, the embossed region for reducing friction is used as the genital area. It is possible to alleviate skin troubles as much as possible by applying to.

As described in detail above, according to the present invention, the coefficient of friction of the embossed region is increased both when standing (0.49 kPa) and when sitting (1.6 kPa) while using the embossed liquid-permeable surface sheet. By setting the coefficient of friction to be less than or equal to the coefficient of friction in the unembossed region, skin troubles can be avoided as much as possible.

The test pieces used in the preliminary test are shown. (A) is a surface optical microscope image of an embossed nonwoven fabric sample, and (B) is a surface optical microscope image of an unembossed nonwoven fabric sample. It is a schematic diagram which shows the linear motion type slip friction test apparatus. It is a time-dependent graph of the friction coefficient of samples A and B. It is a graph which shows the change of the average friction coefficient with respect to the change of the apparent contact pressure of samples A and B. It is a schematic diagram of the apparatus used for the optical microscope observation test. It is a graph which shows the change of the true contact ratio of each sample with respect to the change of contact pressure. It is a top view of the menstrual napkin 1 which concerns on this invention. It is the cross-sectional view. It is an enlarged plan view of the main part of the surface embossing 20. It is a top view of the menstrual napkin which concerns on the 2nd form example. It is a table which showed the list of the physical properties of the non-woven fabric of Samples A to D and the list of the measurement result of the friction coefficient. It is a graph which shows the change of the average friction coefficient with respect to the change of the apparent contact pressure of samples C and D. It is a graph which shows the relationship between the fiber diameter of a non-woven fabric and a friction coefficient at a contact pressure of 1.6 kPa.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Preliminary test]
First, the research conducted by the present inventors in advance for clarifying the influence of the embossing of the non-woven fabric on the frictional properties will be described in detail.
(1) Specimen As the non-woven fabric used for the test, the first layer is "PP / PE, 1.6dt (concentric) regular hydrophilicity: 8gsm", and the second layer is "PET / PE, 3.3dt (eccentric) regular". A non-woven fabric having a two-layer structure of "hydrophilic: 17gsm" was used.

FIG. 1 shows an optical microscope image of the surface of the nonwoven fabric sample used in this study. (A) is a surface optical microscope image of an embossed nonwoven fabric sample (hereinafter referred to as sample A), and (B) is a surface optical microscope image of an unembossed nonwoven fabric sample (hereinafter referred to as sample B). Sample A is embossed with a pattern as shown by a thick wavy line in the figure, and this portion is a recess. The average depth is 577 μm.

(2) Slip friction test
(a) Test method A friction test was conducted using the linear motion type slip friction test device shown in FIG. As a mating material, an artificial skin piece made of polyurethane (contact area: 30 mm × 30 mm) simulating human skin was used. The artificial skin piece is attached to the lower part of the load cell, the non-woven fabric sample is fixed on the stage using double-sided tape, and the artificial skin piece is brought into contact with the stage. Then, a slip friction test was performed by applying a predetermined load to the upper part of the load cell with a weight and reciprocating the stage. The test was conducted under a slip speed of 1 mm / s, a slip distance of 5 mm, a number of friction repetitions of 10 times, and no lubrication in the atmosphere. The vertical load was set to 0.49 kPa and 1.6 kPa, assuming a low contact pressure state and a high contact pressure state applied to the napkins worn while standing and sitting. The slip direction was the machine direction, which is the flow direction of the fibers of the non-woven fabric, and the test was repeated three times under the same conditions in order to obtain reproducibility. In addition, in order to simulate the actual usage environment, the temperature and humidity around the tester were adjusted to 36 ± 1 ° C and humidity 60 ± 2%) using a heater and a humidifier.

For the setting of 0.49 kPa when standing and 1.6 kPa when sitting, an air pack type continuous contact pressure measuring device (AMI Techno Co., Ltd. product number: AMI3037-2) is attached to the shorts and is in activity. The setting was based on the results of continuous measurement of the contact pressure between the standing position and the sitting position, and also considering the constraint conditions from the slip friction tester. The air pack type continuous contact pressure measuring device is a measuring device that traps air in a flat pack, guides it to a pressure sensor outside the contact with a tube connected to the pack, and measures the contact pressure by the differential pressure with the atmosphere. It has the advantage that it can be easily installed on a flexible surface.

(b) Experimental results and discussion Fig. 3 shows the change over time in the friction coefficient when the apparent contact pressure is 1.6 kPa, as a typical example of the change over time in the friction coefficient. In the figure, the solid line and the wavy line show the coefficient of friction of Sample A and Sample B at the 10th repetition, respectively. From the figure, it can be seen that in both samples, the value of the friction coefficient shows a large fluctuation range, but the average value shows an almost constant value. In order to compare between the sample and the contact pressure condition, the average value of the friction coefficient in the period corresponding to 10 to 90% of the slip time in the 10th repetition was used as the average friction coefficient.

Table 1 below shows the measurement results of the friction coefficient, and FIG. 4 shows the change in the average friction coefficient with respect to the change in the apparent contact pressure of each sample. From the figure, both samples show a tendency that the coefficient of friction decreases with increasing contact pressure. When the contact pressure is 0.49 kPa, the embossed sample A has a lower coefficient of friction, but when the contact pressure is 1.6 kPa, the sample B has a lower coefficient of friction due to changes in the contact pressure. It can be seen that the magnitude of the friction coefficient is reversed.

Based on the friction adhesion theory, the coefficient of friction is proportional to the "true contact area" if the shear strength of the adhesion contact surface is constant under the same material and load conditions. Therefore, in order to clarify the change in the true contact area when a load is applied to the nonwoven fabric, an optical microscope observation test was conducted to estimate the approximate value of the true contact area. It should be noted that the "true contact area" is not the apparent contact area but the actual contact area when the object is in contact with the object. Friction itself is a phenomenon that causes the part that is actually in contact microscopically, and the area of this part that is actually in contact is called the "true contact area".
FIG. 5 shows a schematic view of the apparatus used for the optical microscope observation test. As shown in the figure, a glass plate was placed on the non-woven fabric, and a weight of a predetermined weight was further placed on the glass plate. The weight of the weight was adjusted to match the apparent contact pressure 2 conditions in the friction test. The optical microscope was focused on the contact surface between the non-woven fabric and the glass plate, and the area of the fiber existing in the focused range was used for the evaluation as the true contact area. At the time of observation, the temperature of the nonwoven fabric sample was adjusted using a hot plate so that the temperature would be the same as 36 ° C. at the time of the friction test. The observation range was 6.5 x 5.0 mm, and observations were made at 3 randomly selected points, and the average value was used for evaluation.

FIG. 6 shows the change in the true contact ratio of each sample with respect to the change in contact pressure. The true contact ratio is expressed as a percentage of the apparent contact area (the area of the photographing range) of the true contact area. In the figure, the solid line plot shows the data of sample A, and the wavy line plot shows the data of sample B. From the figure, it can be seen that when the contact pressure is 0.49 kPa, the embossed sample A has a smaller true contact ratio than the sample B. On the other hand, in the case of 1.6 kPa, the true contact ratio of sample B is smaller. The change in magnitude between the two samples shows the same tendency as the change in the average friction coefficient with respect to the contact pressure shown in FIG. 4, which is the difference between the friction coefficient and the true contact area in the above-mentioned friction adhesion theory. Qualitatively match the relationship. The difference in the relationship between the contact pressure and the contact area depending on the presence or absence of embossing is considered to be due to the deformation characteristics of the side surface portion of the embossed portion. The side surface of the emboss has a relatively dense structure because the surrounding fibers are drawn in during the embossing process. Since the bottom of the emboss is a recess, it is difficult to make contact with it, and it is considered that the side surface bears the load corresponding to that. In the low load region, the side surface portion does not deform significantly even when a load is applied, and the embossed bottom portion does not contact. Therefore, it is considered that the true contact ratio of the embossed sample A is lower. On the other hand, in the high load range, the side surface part cannot bear the load, the embossed bottom part comes into contact, and the side surface part has fibers densely present, so that the contact area tends to be large and the true contact ratio has increased. Conceivable.

From the above, when the non-woven fabric is embossed, it is expected that the coefficient of friction will be reduced in the low load range (0.49 kPa) such as when standing. On the other hand, in the high load range (1.6 kPa) such as when sitting, it was found that the coefficient of friction may increase due to the increase in the true contact area.

[This menstrual napkin]
According to the artificial menstrual blood dripping test, it was found that the diffusion area was increased by about 60% by embossing, and it was transparent to control the diffusion area of body fluid and reduce the surface residue of menstrual blood and cages. The effect is recognized by the embossing applied to the liquid surface sheet. However, in the slip friction test, the sample A embossed at the time of sitting has a larger friction coefficient than the sample B not embossed, and the magnitude of the friction coefficient may be reversed due to a change in contact pressure. It has been found.

In other words, although embossing is effective in controlling the diffusion area of body fluids and reducing menstrual blood and the surface residue of cages, it increases friction when sitting and tends to cause skin problems such as rubbing. It turned out to be flawed.

In the sanitary napkin according to the present invention for dealing with this problem, a non-woven fabric is used as the liquid-permeable surface sheet, and surface embossing is formed on the non-woven fabric at least on the surface side to be used in an arbitrary pattern. And
The liquid-permeable surface sheet is a non-woven fabric having a two-layer structure composed of an upper layer and a lower layer, and constitutes a surface non-woven fabric in which the upper layer comes into contact with the skin, and the thickness of the fiber having polyethylene terephthalate as a core and a polyethylene sheath. Is composed of short fibers of 2.2 dt or more and 3.0 dt or less, and the lower layer is a crimped fiber having a polyethylene terephthalate as a core and a polyethylene sheath, and the fiber thickness is 4.0 dt or more and 7.0 dt or less, and the upper layer is. Non-woven fabric with a weight ratio of 40% or less of the whole is used,
The friction coefficient was measured for the embossed region including the portion where the surface emboss was formed and the non-embossed region where the surface emboss was not applied by a predetermined slip friction test method on the liquid-permeable surface sheet. When
The measured value in the vertical pressure load state of 0.49 kPa assuming the standing position shows that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the non-embossed region.
The measured value in the vertical pressure load state of 1.6 kPa assuming the time of sitting is also such that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the embossed region.

Hereinafter, this menstrual napkin will be described in detail.

[Basic configuration of menstrual napkin 1]
As shown in FIG. 7, the menstrual napkin 1 according to the present invention has an impermeable back sheet 2 made of a polyethylene sheet, a polypropylene sheet, etc., and a liquid-permeable surface that rapidly permeates menstrual blood, cages, and the like. The sheet 3 is surrounded by an absorber 4 made of cotton-like pulp or synthetic pulp interposed between the two sheets 2 and 3, and the absorber 4 in order to maintain the shape of the absorber 4 and improve the diffusivity. A second sheet 6 made of a hydrophilic non-woven fabric laminated between the crepe paper 5 and the lower layer side of the liquid permeable surface sheet 3 and interposed between the liquid permeable surface sheet 3 and the crepe paper 5, and both sides of the surface. It is composed of side non-woven fabrics 7 and 7 arranged along the longitudinal direction, respectively. Around the absorber 4, at the front and rear edge portions in the longitudinal direction of the napkin, the outer edge portions of the impermeable back sheet 2 and the liquid permeable surface sheet 3 are made of an adhesive such as a hot melt, a heat seal, or the like. The impermeable back sheet 2 and the side non-woven fabric 7 which are joined by an adhesive means and extend laterally from the edge of the absorber 4 at both side edges thereof are bonded with an adhesive such as hot melt or heat. It is joined by an adhesive means such as a seal, and an outer peripheral flap portion F in which the absorber 4 does not exist is formed on the outer periphery.

As the impermeable back sheet 2, a sheet material having at least water impermeability such as an olefin resin sheet such as polyethylene or polypropylene is used, but in addition to this, a laminated non-woven fabric in which a non-woven fabric is laminated on a polyethylene sheet or the like, and further A non-woven fabric sheet (in this case, the waterproof film and the non-woven fabric form an impermeable back sheet) can be used after substantially ensuring the impermeable property by interposing a waterproof film. In recent years, from the viewpoint of preventing stuffiness, those having moisture permeability have tended to be used. This water-impervious / moisture-permeable sheet material is a microporous sheet obtained by melting and kneading an inorganic filler in an olefin resin such as polyethylene or polypropylene to form a sheet, and then stretching it in a uniaxial or biaxial direction. Is.

Next, as the liquid-permeable surface sheet 3, a perforated or non-perforated non-woven fabric is preferably used. The material fibers constituting the non-woven fabric can be, for example, olefin-based fibers such as polyethylene or polypropylene, synthetic fibers such as polyester-based and polyamide-based, recycled fibers such as rayon and cupra, and natural fibers such as cotton. A non-woven fabric obtained by an appropriate processing method such as a lace method, a spunbond method, a thermal bond method, a melt blown method, or a needle punching method can be used. Among these processing methods, the spunlace method is excellent in that it is flexible, the spunbond method is excellent in drapeability, and the thermal bond method and the air-through method are excellent in that they are bulky and soft. The synthetic fiber may be a mixture of, for example, a polyolefin-based fiber such as polyethylene or polypropylene, a polyester-based fiber such as polyethylene terephthalate or polybutylene terephthalate, a polyamide-based fiber such as nylon, or a copolymer thereof. .. Further, composite fibers such as core-sheath type fibers having a high melting point fiber as a core and a low melting point fiber as a sheath, side-by-side type fibers, and split type fibers can also be used.

As will be described in detail later, the liquid-permeable surface sheet 3 is formed with surface embossing 20 in an arbitrary pattern at least on the surface side to be used with respect to the non-woven fabric. The illustrated example is a surface emboss 20 composed of a combination of a predetermined wavy pattern and a dot-shaped pattern. The liquid-permeable surface sheet 3 will be described in more detail later.

The absorber 4 interposed between the liquid-permeable back sheet 2 and the liquid-permeable front sheet 3 is composed of, for example, a fluff-like pulp and a water-absorbent polymer. The water-absorbent polymer is mixed in the pulp constituting the absorber, for example, as a granular powder. Examples of the pulp include cellulose fibers such as chemical pulp and dissolved pulp obtained from wood, and artificial cellulose fibers such as rayon and acetate. It is preferably used in terms of price.

Further, synthetic fibers may be mixed with the absorber 4. As the synthetic fiber, for example, polyolefin-based fibers such as polyethylene or polypropylene, polyester-based fibers such as polyethylene terephthalate and polybutylene terephthalate, polyamide-based fibers such as nylon, and copolymers thereof can be used, and these two types can be used. It may be a mixture. Further, composite fibers such as core-sheath type fibers having a high melting point fiber as a core and a low melting point fiber as a sheath, side-by-side type fibers, and split type fibers can also be used. In the case of hydrophobic fibers, it is desirable to use the synthetic fibers surface-treated with a hydrophilic agent so as to have an affinity for body fluids.

When the crepe paper 5 surrounding the absorber 4 is provided as in this example, as a result, the crepe paper 5 is interposed between the liquid-permeable surface sheet 3 and the absorber 4, and the crepe paper 5 is absorbent. The excellent crepe paper 5 quickly diffuses the body fluid and prevents the menstrual blood from regurgitating.

The second sheet 6 made of a hydrophilic non-woven fabric laminated on the lower layer side of the liquid-permeable surface sheet 3 includes, for example, olefin-based synthetic fibers such as polyethylene and polypropylene, polyester-based and polyamide-based synthetic fibers, as well as rayon and cupra. It can be a natural fiber such as recycled fiber or cotton, and a non-woven fabric obtained by an appropriate processing method such as a spunlace method, a spunbond method, a thermal bond method, a melt blown method, or a needle punching method can be used. In order to impart hydrophilicity, a method of coexisting and polymerizing a compound having a hydrophilic group, for example, an oxidation product of polyethylene glycol, or treatment with a metal salt such as stannic chloride is performed in the process of producing synthetic fibers. Synthetic fibers can be swelled or made porous by a method of partially dissolving the surface to make them porous and depositing metal hydroxides, and the capillary phenomenon can be applied to give hydrophilicity. The second sheet 6 is preferably bonded to the liquid permeable surface sheet 3.

On the other hand, side nonwoven fabrics 7 and 7 are provided on both sides of the surface of the menstrual pad 1 along the longitudinal direction and over almost the entire length of the napkin 1, respectively, and a part of the side nonwoven fabrics 7 and 7 is provided. Wing-shaped flaps W and W are formed by a part of the impermeable back sheet 2 extending laterally and also extending laterally.

As the side nonwoven fabric 7, a water-repellent treated nonwoven fabric or a hydrophilic treated nonwoven fabric can be used from the viewpoint of important functions. For example, if you place importance on functions such as preventing menstrual blood and vaginal discharge from penetrating, or enhancing the feel of the skin, water repellent treatment coated with silicone-based, paraffin-based, alkylchromic chloride-based water repellent, etc. It is desirable to use non-woven fabric. Further, if the absorbability of menstrual blood and the like in the wing-shaped flaps W and W is emphasized, a method of coexisting and polymerizing a compound having a hydrophilic group, for example, an oxidation product of polyethylene glycol in the process of producing synthetic fibers, or , Treat with a metal salt such as stannic chloride to partially dissolve the surface to make it porous and deposit the metal hydroxide to make the synthetic fiber swell or porous, and apply the capillary phenomenon to make it hydrophilic. It is desirable to use the hydrophilically treated non-woven fabric given the above.

<Liquid permeable surface sheet 3>
In the present invention, a non-woven fabric is used particularly as a liquid-permeable surface sheet, and the surface emboss 20 is formed on the non-woven fabric at least on the surface side to be used in an arbitrary pattern.

The surface embossing 20 shown in FIG. 7 is formed on the entire surface of the liquid permeable surface sheet 3, but is formed in at least a partial region including a body fluid draining site. The surface embossing 20 can be formed by a pattern consisting of straight lines, dotted lines, wavy lines, curves, or a combination thereof. The illustrated example is formed with the following wavy pattern.

The wavy pattern, as shown in detail in FIG. 9, is a protrusion 21 to one side and a protrusion 22 to the other side in the width direction of the napkin along the substantially longitudinal direction of the napkin in a plan view. The first wavy pattern 23 in which the first wavy pattern 23 is alternately repeated and the second wavy pattern 24 in which the first wavy pattern 23 is inverted in the napkin width direction are arranged alternately in the napkin width direction as a wavy pattern. .. By providing the surface embossing 20 having such a wavy pattern on the liquid-permeable surface sheet 3, the body fluid can be diffused in the longitudinal direction, and at the same time, the liquid-permeable surface sheet can be made from the projecting portions 21 and 22 as a base point. 3 is easily deformed along the shape of the body, and wrinkles and twists due to the liquid-permeable surface sheet 3 not following the shape of the body can be prevented.

As shown in FIG. 9, by providing the surface embossing 20 of the wavy pattern, the wide portion 25 and the narrow portion 26 having different separation widths between the first wavy pattern 23 and the second wavy pattern 24 are provided. And are formed alternately and repeatedly in the longitudinal direction of the napkin.

The liquid-permeable surface sheet 3 is adhered to the lower flat second sheet 6 at least at the contact surface portion with the bottom surface of the surface emboss 20 of the wavy pattern by heat fusion or an adhesive such as hot melt, and is second. It is integrated with the sheet 6.

On the other hand, in order to reduce the surface residue of the body fluid in the wide portion 25 and reduce the contact area with the skin, dot-shaped embossing 27 is provided on all or part of the wide portion 25 as shown in the illustrated example. Is preferable.

The surface embossing 20 of the wavy pattern forms periodic intermittent portions 28, 28 ... In accordance with the period of the wavy pattern so that the wavy pattern is intermittently provided in the substantially longitudinal direction of the napkin. Can be done. In the example of the figure, the intermittent portion 28 is provided at the top of the protruding portion 22 toward the other side in the width direction of the napkin. By providing the intermittent portion 28, the liquid-permeable surface sheet 3 is easily deformed along the shape of the body with the intermittent portion 28 as a base point. If the intermittent length of the intermittent portion 28 is too large, the continuity of the wavy pattern is significantly impaired and the effect as the above-mentioned base point is lost. Therefore, the intermittent length of the intermittent portion 28 in the longitudinal direction of the napkin is lost. Is preferably 1 mm or less.

The liquid-permeable surface sheet 3 uses fibers having a fiber diameter of 2.2 dt or more and 3.0 dt or less as constituent fibers of a non-woven fabric that comes into contact with the skin. By setting the fiber diameter to 2.2 dt or more, as shown in the column of <Slip friction test of liquid permeable surface sheet> described later, the liquid permeable surface sheet 3 is subjected to the surface embossing by a predetermined slip friction test method. When the coefficient of friction was measured for the embossed region including the portion where 20 was formed and the non-embossed region where the surface embossed 20 was not imparted, as shown in FIG. 11, an upright position was assumed. The measured value in the vertical pressure load state of 0.49 kPa is that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the non-embossed region, and the friction coefficient of the embossed region is 1.6 kPa in the vertical pressure load state assuming sitting. The measured value can also be such that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the non-embossed region.

That is, by setting the fiber diameter of the non-woven fabric to 2.2 dt or more, the magnitude of the friction coefficient changes depending on the change in contact pressure in the magnitude relationship between the coefficient of friction when standing (0.49 kPa) and the coefficient of friction when sitting (1.6 kPa). It is possible to prevent the phenomenon of reversal, and in both the standing and sitting maintenance cases, the friction coefficient of the embossed area can be made lower than the friction coefficient of the non-embossed area, preventing the occurrence of skin troubles. Or it can be alleviated. The embossed 20 of the embossed region is a recess recessed on the non-skin side, and the non-embossed region constitutes a flat surface.

In addition, regarding the upper limit value of the fiber diameter of the non-woven fabric used as the liquid-permeable surface sheet 3, 3.0 dt, if the fiber diameter is increased too much, the voids between the fibers increase, and the liquid permeability improves, but relapse occurs. Since problems are likely to occur, the value on the upper limit side that can be generally taken as the surface sheet 3 of this type of sanitary napkin is set.

The depth of the surface embossing 20 is preferably 400 μm or more and 700 μm or less, preferably 500 μm or more and 600 μm or less on average.

The slip friction test method is a friction test performed according to the following procedures (1) to (6).
(1) Perform a friction test using a direct-acting slip friction tester (Trinity Lab Co., Ltd. Speed Fluctuation Friction Tester Type: μv-1000).
(2) Using an artificial skin piece made of polyurethane that imitates human skin, attach the artificial skin piece to the lower part of the load cell, fix the non-woven fabric sample on the stage, and bring the artificial skin piece into contact.
(3) The vertical load is applied by a weight on the upper part of the load cell so that it is equivalent to the apparent contact pressure (standing: 0.49 kPa, sitting: 1.6 kPa) applied to the attached napkin when standing and sitting. A slip friction test is performed by applying a load and reciprocating the stage.
(4) The test shall be conducted under a slip speed of 1 mm / s, a slip distance of 5 mm, a friction repetition rate of 10 times, and no lubrication in the atmosphere.
(5) The slip direction is the machine direction, which is the flow direction of the fibers of the non-woven fabric, and the test is repeated three times under the same conditions in order to obtain reproducibility.
(6) The average value of the friction coefficient in the period corresponding to 10 to 90% of the slip time in the 10th repetition is used as the friction coefficient.

Regarding the friction coefficient measurement for the unembossed region where the surface embossing is not applied, when the surface embossing 20 is formed on the entire surface of the surface sheet of this embodiment, the embossing between the embossing and the embossing is performed. The coefficient of friction may be measured with the unapplied area as the measurement target, but if the measurement target area is particularly narrow, the area of the artificial skin piece of the slip friction test device may be reduced or the slip distance may be reduced. It is possible to deal with it. Separately, if a non-woven fabric sheet of the same material before embossing is available, a friction test may be performed on the obtained non-woven fabric.

It is desirable that the liquid-permeable surface sheet 3 is a two-layer non-woven fabric having a crimped fiber layer integrally under the layer separately from the layer in contact with the skin. Specifically, a two-layered non-woven fabric consisting of an upper layer and a lower layer is used, the upper layer is made of a polymer polymer and fibers having a fiber diameter of 2.2 dt or more and 3.0 dt or less are used, and the lower layer is made of a high molecular polymer. A non-woven fabric using crimped fibers having a fiber diameter of 4.0 dt or more and 7.0 dt or less can be used. The lower crimped fiber layer can elastically support the vertical compressive force, improving the cushioning property in the thickness direction, the compression followability, and the deformation resistance when the compressive force is applied to the non-woven fabric. It becomes possible.

Further, as a preferable example of the two-layer structure, a non-woven fabric having a two-layer structure composed of an upper layer and a lower layer is used, and the upper layer is a short fiber having a polyethylene terephthalate as a core and a polyethylene sheath as a fiber having a thickness of 2.2 dt or more and 3.0 dt or less. The lower layer is a crimped fiber with polyethylene as a sheath with polyethylene terephthalate as the core, and the fiber is made of short fibers with a thickness of 4.0 dt or more and 7.0 dt or less, and the upper layer is 40% or less by weight of the whole. It can be a non-woven fabric. In this preferred example, a core-sheath type fiber having polyethylene terephthalate as a core material is used. Polyethylene terephthalate has relatively higher shape stability than polyolefin-based fibers, and can improve cushioning property, compression followability, and deformation resistance when subjected to compressive force.

In the production of the liquid-permeable surface sheet 3 on which the surface emboss 20 is formed, for example, the first emboss roll, the second emboss roll, and the anvil roll having a smooth surface are arranged in a vertical direction from the lower stage side. A roll device is used. The first embossing roll and the second embossing roll are paired, and a liquid-permeable surface sheet is passed between these embossing rolls to impart uneven embossing, and the space between the second embossing roll and the anvil roll is imparted. While passing through the liquid-permeable surface sheet 3, the lower second sheet 6 is allowed to enter between the second emboss roll and the anvil roll, and the liquid-permeable surface sheet 3 and the second sheet 6 are overlapped with each other, and the second sheet is overlapped. At least one side of the embossed roll and the anvil roll is kept heated to a predetermined temperature, and the bottom surface of the recess of the liquid permeable surface sheet 3 and the second sheet 6 are joined by heat fusion. The method of joining the liquid-permeable surface sheet 3 and the second sheet 6 may be a joining method using an adhesive such as hot melt.

In the assembly of the above-mentioned menstrual napkin 1, the liquid-permeable front sheet 3 having the absorbent body 4 surrounded by the crepe paper 5 and the surface emboss 20 formed on the impermeable back sheet 2 cut into a predetermined product shape. The second sheet 6 and the side nonwoven fabric 7 are laminated, and the liquid-permeable surface sheet 3, the second sheet 6 and the side nonwoven fabric 7 are simultaneously cut into a predetermined shape.

<Example of the second form>
In the sanitary napkin 1 of the above embodiment, the surface embossing 20 is formed over the entire surface of the liquid permeable surface sheet 3, but the surface embossing 20 can be partially formed. For example, as shown in FIG. 10, an embossing region including a portion where the surface embossing 20 is formed is arranged in a longitudinal intermediate portion including a body fluid discharge portion H of the liquid permeable surface sheet 3, and the liquid permeable surface. It is also possible to arrange the unembossed area where the surface embossing is not applied at the front and rear ends of the sheet 3.

The body fluid discharged to the body fluid discharge site H is quickly diffused in the longitudinal direction, and the front and rear ends in the longitudinal direction are set as unembossed regions to suppress the diffusion, and the intermediate portion in the longitudinal direction including the body fluid discharge site H is included. Is an embossed area where friction is reduced, and by applying this to the vulva, it is possible to alleviate skin troubles as much as possible.

<Slip friction test of liquid-permeable surface sheet>
In the above-mentioned <preliminary test>, when the contact pressure is standing (0.49 kPa), the embossed sample A has a smaller coefficient of friction, but the contact pressure is seated (1.6 kPa). In sample B, which was not embossed, the coefficient of friction was smaller, and the magnitude relationship of the coefficient of friction was reversed by the change in contact pressure. As a result of various studies and tests on the reason, it was concluded that the fiber diameter of the non-woven fabric layer in contact with the skin is greatly related.

Therefore, the results of performing the same slip friction test on the test pieces having different fiber diameters will be described in detail.

(1) Test piece The non-woven fabric material is "PET / PE, 2.2dt (concentric) regular hydrophilicity: 8gsm" for the first layer, and "PET / PE, 6.6dt (eccentric) regular hydrophilicity: 17gsm" for the second layer. It has a two-layer structure.

The sample C which was embossed as shown in FIG. 1 (A) was used as sample C, and the sample which was not embossed was used as sample D. The embossing depth is 577 μm on average.

The difference from the test piece used in the above-mentioned <preliminary test> is that the material of the first layer was changed from PP / PE to PET / PE, and the fiber diameter was changed from 1.6 dt to 2.2 dt, and the second layer. The fiber diameter of the eye was changed from 3.3dt to 6.6dt. The physical property values of each of the samples A to D are shown in the list of FIG. 11 so as to be easy to compare.

The friction test was performed on the sample C and the sample D by the same method as the slip friction test performed in the <preliminary test>. The results are shown in Table 2 below and shown in a graph in FIG.

In these Samples C and D, when the contact pressure is standing (0.49 kPa), the embossed sample C has a smaller coefficient of friction and the contact pressure is seated (1.6 kPa). The embossed sample C had a smaller friction coefficient, and the magnitude relationship of the friction coefficient was not reversed by the change in the contact pressure.

In the present invention, the contact pressure at the time of sitting is set to 1.6 kPa, but it has been found that the maximum contact pressure may be 4.9 kPa depending on the posture. The numerical value of the friction coefficient when the contact pressure is 4.9 kPa is put on each of the samples A to D. As in the case of this excessive seating (4.96 kPa), the relative relationship between samples A and B with embossing at the time of sitting has a larger coefficient of friction than without embossing. The relative relationship between the samples C and D with embossing when seated has the same tendency as the friction coefficient is smaller than without embossing.

As a result of obtaining the above findings, the coefficient of friction of the embossed sample C is smaller and the contact pressure is smaller even when the contact pressure is seated (1.6 kPa), regardless of the fiber diameter. From the friction test results of the samples A to D, it was derived by the following procedure whether the magnitude relation of the friction coefficient was not reversed by the change of.

As shown in FIG. 13, on a graph in which the horizontal axis is the fiber diameter (dt) of the non-woven fabric and the vertical axis is the coefficient of friction, the fiber diameter of sample A (with embossing) and sample B (without embossing) is 1.6 dt. The coefficient of friction of sample A (with embossing) 0.27 and the coefficient of friction of sample B (without embossing) 0.25 are plotted at the position of. For sample C (with embossing) and sample D (without embossing), the coefficient of friction of sample C (with embossing) 0.22 and the friction of sample D (without embossing) at a contact pressure of 1.6 kPa at the position of the fiber diameter of 2.2 dt. Plot the coefficient 0.24.

1 ... sanitary napkin, 2 ... impermeable back sheet, 3 ... liquid permeable front sheet, 4 ... absorber, 5 ... crepe paper, 6 ... second sheet, 7 ... side non-woven fabric, 20 ... surface embossing, 21 ... One side ridge, 22 ... the other side ridge, 23 ... first wavy pattern, 24 ... second wavy pattern, 25 ... wide part, 26 ... narrow part, 27 ... dot embossing

Claims (1)

In a sanitary napkin in which an absorber is interposed between a liquid-permeable front sheet and a back sheet,
As the liquid-permeable surface sheet, a non-woven fabric is used, and at least on the surface side to be used with respect to the non-woven fabric, in a plan view, along the longitudinal direction of the menstrual pad, a protrusion toward one side in the width direction of the napkin. The first wavy pattern in which the portion and the protruding portion to the other side are alternately repeated and the second wavy pattern in which the first wavy pattern is inverted in the napkin width direction are alternately arranged in the napkin width direction. The surface embossing is formed in a wavy pattern, the depth of the surface embossing is 400 μm or more and 700 μm or less, and the surface embossing is formed in the intermediate portion in the longitudinal direction including the body fluid discharge portion of the liquid permeable surface sheet. An embossed region including a portion is arranged, and an embossed unembossed region without the surface embossing is arranged at the front and rear ends of the liquid permeable surface sheet.
The liquid-permeable surface sheet is a non-woven fabric having a two-layer structure composed of an upper layer and a lower layer, and constitutes a surface non-woven fabric in which the upper layer comes into contact with the skin . A crimped fiber made of short fibers having a thickness of 2.2 dt or more and 3.0 dt or less using a sheath-type fiber, and the lower layer is an eccentric core-sheath-type fiber having a core of polyethylene terephthalate and a sheath of polyethylene. A non-woven fabric is used, which consists of short fibers with a thickness of 4.0 dt or more and 7.0 dt or less, and the upper layer has a weight ratio of 40% or less of the whole.
The coefficient of friction of the liquid-permeable surface sheet was measured by the following slip friction test method for the embossed region including the portion where the surface emboss was formed and the non-embossed region where the surface emboss was not applied. When
The measured value in the vertical pressure load state of 0.49 kPa assuming the standing position shows that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the non-embossed region.
A sanitary napkin characterized in that the friction coefficient of the embossed region is equal to or less than the friction coefficient of the non-embossed region even in the measured value under a vertical pressure load state of 1.6 kPa assuming the time of sitting.
(Slip friction test method)
(1) Perform a friction test using a direct-acting slip friction tester (Trinity Lab Co., Ltd. Speed Fluctuation Friction Tester Type: μv-1000).
(2) Using an artificial skin piece made of polyurethane that imitates human skin, attach the artificial skin piece to the lower part of the load cell, fix the non-woven fabric sample on the stage, and bring the artificial skin piece into contact.
(3) The vertical load is applied by a weight on the upper part of the load cell so that it is equivalent to the apparent contact pressure (standing: 0.49 kPa, sitting: 1.6 kPa) applied to the attached napkin when standing and sitting. A slip friction test is performed by applying a load and reciprocating the stage.
(4) The test shall be conducted under a slip speed of 1 mm / s, a slip distance of 5 mm, a friction repetition rate of 10 times, and no lubrication in the atmosphere.
(5) The slip direction is the machine direction, which is the flow direction of the fibers of the non-woven fabric, and the test is repeated three times under the same conditions in order to obtain reproducibility.
(6) The average value of the friction coefficient in the period corresponding to 10 to 90% of the slip time in the 10th repetition is used as the friction coefficient.

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