JP2002065741A - Absorbent articles - Google Patents

Abstract

(57) [Problem] To provide an absorbent article capable of obtaining a flexible fit to a movement of a body or clothes and a good wearing feeling. SOLUTION: It is substantially provided with a liquid-permeable surface layer 2, a liquid-impermeable back layer 3, and a liquid-retentive absorbing layer 4 interposed between the surface layer 2 and the back layer 3. A vertically long absorbent article. The bending rigidity El when the central portion of the absorbent article is bent along the width direction so that the surface layer side is concave, so that the central portion is concave on the surface layer side along the longitudinal direction. It is characterized by a lower bending rigidity Ec when bent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a sanitary napkin,
The present invention relates to an absorbent article such as a panty liner.

[0002]

2. Description of the Related Art As a conventional technique relating to a thin sanitary napkin, for example, a technique described in Japanese Patent Publication No. 7-506035 is known. The sanitary napkin of this technology has a stiffer central longitudinal region to provide greater flexibility resistance than that of the lateral lateral regions, thereby improving comfort.

However, like the sanitary napkin described above,
In the case of simply increasing the flexibility resistance in the central region in the longitudinal direction as compared with the lateral region in the longitudinal direction, a flexible fit to the movement of the body or clothes may not be obtained in some cases.

[0004] Accordingly, an object of the present invention is to provide an absorbent article capable of obtaining a flexible fit to a movement of a body or clothing and a good feeling of wearing.

[0005]

The present invention comprises a liquid-permeable surface layer, a liquid-impermeable back layer, and a liquid-retentive absorbing layer interposed between the surface layer and the back layer. In the substantially vertically absorbent article, the bending rigidity El when the central portion of the absorbent article is bent along the width direction so that the surface layer side is concave is formed in the longitudinal direction. The above object has been achieved by providing an absorbent article characterized by having a flexural rigidity Ec lower than that when the surface layer is bent so that the surface layer side becomes concave along the line.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an absorbent article according to the present invention will be described based on preferred embodiments with reference to the drawings.

FIG. 1 and FIG. 2 show an embodiment in which the absorbent article of the present invention is applied to a sanitary napkin (hereinafter, simply referred to as a napkin).

The napkin 1 has a substantially vertically long shape, and has a top sheet 2 as a liquid-permeable surface layer, a back sheet 3 as a liquid-impermeable back layer, and the top sheet 2 and the back sheet 3. And a liquid-retentive absorber (absorbing layer) 4 interposed between them.

On both sides of the napkin 1, a top sheet 2 is provided.
A water-repellent sheet 5 is provided which covers both ends in the width direction of the napkin 1 and both side edges of the absorber 4 and extends in the width direction at the center in the longitudinal direction of the napkin 1. Is formed.

The napkin 1 has a pair of wings 6 and 6 fixed to clothes on both sides thereof. The wing portion 6 is formed by joining the back sheet 3 and the sheet 5 at an extending portion in the width direction.

An adhesive (not shown) is coated on the upper surface of the back sheet 3, and the absorbent 4
Are fixed to the back sheet 3. On the lower surface of the back sheet 3, pressure-sensitive adhesives 7 and 8 are applied to portions located below the absorber 4 and portions located at the wings 6, respectively. These adhesives 7 and 8 are protected by a release sheet (not shown) when the napkin 1 is not used.

The top sheet 2, the back sheet 3 and the sheet 5 are joined at a peripheral portion of the napkin 1 with a predetermined width by heat sealing. Further, the top sheet 2 and the sheet 5 are joined by heat sealing at a predetermined width in the overlapping portion.

The absorber 4 is composed of an absorbent sheet containing a superabsorbent polymer inside. That is, the absorbent body 4 includes two absorbent sheets included in the absorbent sheet 40, the absorbent sheet 40 being disposed such that both end portions thereof are bent toward the back sheet 3 side and overlapped without being joined. 41. By arranging the both end portions of the absorbent sheet 40 in such a manner as described above, even when the napkin 1 is deformed so that the top sheet 2 side becomes concave, the absorbent sheet 40 is so formed as to eliminate the distortion.
Can be deformed, and the napkin 1 is easily deformed into a shape that fits the body as a whole. The absorbent sheet 41 has an outer shape smaller than that of the top sheet 2 and is disposed substantially at the center of the absorbent sheet 40. By arranging the absorbent sheet 41 at substantially the center of the absorbent sheet 40 in this manner, the peripheral portion of the napkin (absorbent article) 1 is concave on the top sheet (surface layer) 2 side along the longitudinal direction as described later. The bending stiffness Es when bent so that
Place the center portion of the napkin 1 along the longitudinal direction
Is lower than the bending stiffness Ec when bent in a concave shape. In addition, the absorbent sheet 40 is subjected to crepe processing in the form of wrinkles or waves extending in the width direction. By creping the surface of the absorbent sheet 40 in this manner, the napkin 1
When the central portion of the napkin 1 is bent along the width direction so that the top sheet 2 is concave, the bending stiffness El is obtained when the central portion of the napkin 1 is bent along the longitudinal direction so that the top sheet 2 is concave. Is lower than the bending rigidity Ec.

The napkin 1 is provided on the surface of the top sheet 2.
A leak-proof groove 20 for heat-sealing and integrating the top sheet 2 and the absorber 4 is provided. Leak-proof groove 20
Is an elongated ring-shaped groove formed by passing through a heat roll having an emboss pattern and having a narrowed central portion in the longitudinal direction.
The leak-proof groove 20 has a function of preventing the liquid absorbed in the absorber 4 from diffusing to the surroundings, in addition to guiding the liquid to the absorber 4, and a napkin associated with opening / closing a foot or walking. 1
Has a function of preventing the compressive stress deformation in the width direction from being transmitted to the central portion, so that the central portion of the napkin 1 can be surely prevented from being twisted. That is,
The compressive stress in the width direction is reduced at the peripheral portion of the napkin 1 and the transmission to the absorber 4 is divided by the leakage preventing groove 20, so that the central portion can be further stabilized against the warping. Has become.

The napkin (absorbent article) 1 has a bending rigidity El when the center portion is bent along the width direction so that the top sheet (surface layer) 2 side is concave, and the center portion extends along the longitudinal direction. The bending stiffness Ec when the top sheet 2 is bent so as to be concave is lower.
By having such bending stiffness, it is possible to flexibly deform along the width direction while flexing and deforming along the longitudinal direction, and it is possible to obtain a fit that hardly creates a gap with the body as a whole product, Lateral leakage and longitudinal leakage can be effectively prevented. In addition, since the whole product fits flexibly, there is little unreasonable deformation, and as a result, twisting can be effectively prevented.

The central portion of the napkin (absorbent article) 1
As shown in FIG. 3, the central portion in the width direction means a region having a width Wc of at least 20% with respect to the entire width W of the absorber 4 around the center line Cy in the width direction. In the direction, it means a region having a length Lc of at least 20% of the entire length L of the absorber 4 about the longitudinal center line Cx.

The peripheral portion of the napkin (absorbent article) 1
In the width direction, it means a region Ws of about 20% from at least both sides with respect to the entire width W of the absorber, and in the longitudinal direction, at least with respect to the entire length L of the absorber around the width direction center line Cx. This means a region Lc having a length of 20%.

In the napkin (absorbent article) 1, the bending stiffness Ec is determined from the viewpoint that the napkin fits the body as a whole, but does not easily twist or leak.
It is preferably 0.2~1.0gf · cm ² / cm, and more preferably 0.4~0.8gf · cm ² / cm.

In the napkin (absorbent article) 1, the bending stiffness El is 0.1 from the viewpoint of fitting the whole body so as not to form a gap and making it hard to leak.
０．８0.8 gf · cm ² / cm,
More preferably, it is 0.2 to 0.6 gf · cm ² / cm.

The bending stiffness Es is 0.15 to 0.8 from the viewpoint that the deformation of the compressive stress at the time of attachment to the center portion is reduced, the deformation is less likely to occur, and a more stable absorbing structure is used to prevent leakage.
gf · cm ² / cm, preferably from 0.2 to
More preferably, it is 0.7 gf · cm ² / cm.

In the napkin (absorbent article) 1,
Indicates that the peripheral part is deformed preferentially and the central part corresponds to the excretion part
Has an absorbent structure that fits the body more stably
At the point where the peripheral portion extends along the longitudinal direction of the surface
Bending stiffness Es when bent so that the layer side becomes concave
Is preferably lower than the bending rigidity Ec.
Thus, the bending rigidity Es is made lower than the bending rigidity Ec.
As a specific method, napkins (absorbent articles) 1
The peripheral portion is thicker than the peripheral portion.
Increasing the basis weight of the absorber in the central part rather than the side parts;
Increase the density of the absorber in the central part from the peripheral part, etc.
Technique. The central part of the absorbent article
If it is thicker than the peripheral part,
The thickness of the part is 1.5 to 3.5 mm, and the thickness of the peripheral part is 1 to
2.5 mm, more preferably 2.
5 to 3.5 mm. In addition, the inner part is more than the peripheral part.
When increasing the basis weight of the absorber in the center, it is preferable
Is 150 to 500 g / m of the basis weight of the absorber in the central part.
^TwoThe basis weight of the absorber in the peripheral portion is 50 to 300 g / m^Two
And more preferably the basis weight of the absorber in the central part
200-350g / m^Two, The basis weight of the absorber in the peripheral part
80 to 200 g / m^TwoAnd Furthermore, from the peripheral part
Also when increasing the density of the absorber in the central part
Preferably reduces the density of the absorber in the central part by 0.0
3 to 0.8 g / cm ^Three, Density of the absorber in the peripheral part
0.01 to 0.5 g / cm^ThreeAnd more preferably the
The density of the absorber at the center is 0.03 to 0.3 g / c.
m^ThreeThe density of the absorber in the peripheral portion is set to 0.02 to 0.2.
2g / cm^ThreeAnd

The actual size of the central portion of the napkin (absorbent article) 1 varies depending on its use.
In a normal-sized sanitary napkin for daytime, the width of the central portion is preferably 10 to 50 mm, and 20 mm.
More preferably, it is で 40 mm. In addition, absorber 4
Is preferably 50 to 90 mm, and 60 to 90 mm.
More preferably, it is 80 mm. Further, the length of the central portion is preferably 30 to 100 mm, and 40 to 100 mm.
More preferably, it is 90 mm. The length of the absorber is preferably 140 to 240 mm,
More preferably, it is 0 to 210 mm.

The actual size of the peripheral portion of the napkin (absorbent article) 1 varies depending on its use.
In a normal size sanitary napkin for daytime, the width of the peripheral portion is preferably 10 to 40 mm, and 15 to 40 mm.
More preferably, it is about 35 mm.

The napkin 1 (absorbent article) is preferably thin, and its maximum thickness is preferably 3.5 mm or less, more preferably 3.0 mm or less. By making the thickness in such a range, it is thin, and fit with the body and integrity with clothing can be obtained,
A natural feeling without discomfort can be obtained.

The material for forming the top sheet (surface layer) 2 is not particularly limited, and various materials conventionally used for absorbent articles, such as a nonwoven fabric type and a perforated film in which a film is perforated, are not particularly limited. Can be used for, polyethylene, polypropylene, polyester, polyethylene-polypropylene composite fiber, polyethylene-polypropylene composite fiber or by mixing them to produce a nonwoven fabric,
An apertured nonwoven fabric subjected to a three-dimensional aperture treatment is preferred. The apertured film has a large contact area with the skin of the wearer, and the unopened portion does not have air permeability. The part has air permeability, and since it is three-dimensionally open, it has air permeability even in the plane direction of the opening side of the surface material, so that the humidity rise in the wearing and the occurrence of stuffiness due to it It can be suppressed more effectively. In the present invention, most of the body fluid absorbed by the absorbent layer is absorbed and retained by the polymer, and the liquid return to the surface layer is extremely small, so that the disadvantage of the conventional nonwoven fabric type is solved.

The back sheet (back layer) 3 is preferably water vapor permeable. By making the back layer water vapor permeable, water vapor resulting from sweating of the wearer due to exercise or the like can be efficiently radiated to the outside through the back layer, and the absorbing layer can absorb and retain most of the body fluid Due to the synergistic effect of the above, it is possible to effectively prevent an increase in humidity in the clothes and the occurrence of stuffiness due to the increase. In addition, when the absorbing layer is the above-mentioned thin type, the heat trapped in the clothing is easily released, and the structure of the absorbent article keeps the temperature and humidity comfortably.

The degree of water vapor permeability of the back sheet (back layer) 3 is 0.3 g of moisture permeability measured in accordance with JIS Z0208 (hereinafter referred to as moisture permeability measured by this method). / (100cm ²・ hr)
Above, especially 1.0 to 5.0 g / (100 cm ² · hr)
Is preferred from the viewpoint of preventing a rise in humidity in the clothes. The material for forming the back layer when water vapor permeable is not particularly limited as long as it has liquid impermeability and has water vapor permeability, but may be a hydrophobic thermoplastic resin made of polyethylene, polypropylene, or a mixture thereof. , A fine inorganic filler made of calcium carbonate, barium sulfate, or the like is melted and mixed to form a film, and the film is dried.
A porous film obtained by axial or biaxial stretching, a waterproof paper subjected to a size treatment, a nonwoven fabric made of hydrophobic fine thermoplastic fibers obtained by a method such as a melt blown, and a porous film thereof, Examples include a waterproof paper, a composite sheet of a nonwoven fabric made of hydrophobic fine thermoplastic fibers, and the like.

As the absorbent sheet used for the absorbent body (absorbing layer) 4, a sheet obtained by mixing hydrophilic fibers and superabsorbent polymer particles is preferably used. As the material for forming the hydrophilic fiber, it is preferable to use a non-swellable hydrophilic fiber and a low-swellable hydrophilic fiber described below. Examples of the material for forming the non-swellable fiber include resins that do not swell themselves, for example, synthetic resins such as polyethylene, polypropylene, polyester, polyurethane, and composites of two or more of these. Since the surface of these synthetic resins is hydrophobic, it is necessary to perform a hydrophilic treatment. As a method of the hydrophilic treatment, a method of spraying and coating a solution of a surfactant on the fiber made of the synthetic resin and attaching the solution to the surface or kneading a hydrophilic surfactant in advance into the synthetic resin is used. After that, there is a method of forming into a fiber, and bleeding a surfactant on the surface.

As the surfactant used for the hydrophilic treatment,
There is no particular limitation as long as it is a hydrophilic surfactant having a hydrophilic group and a lipophilic group, but an anionic surfactant and a nonionic surfactant having a high addition mole number of ethylene oxide are preferred. Specifically, sulfosuccinates,
Alkyl ether sulfate, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, glycerin fatty acid ester and the like are preferable.
Among these surfactants, those which can impart sufficient hydrophilicity when the usage ratio to the synthetic resin is about 0.05 to 3% by weight are preferable. Surfactants can be used alone or in combination of two or more.

As the low swelling hydrophilic fiber, the amount of water retained when centrifugally dewatered after swelling with water (hereinafter referred to as “water swelling”).
(Referred to as “centrifugal retention of water”) is preferably 0.7 g /
g, more preferably 0.5 g / g or less. As a material for forming such a fiber, a material that does not require a hydrophilic treatment, that is, a material having a hydrophilic surface itself, may be used. Examples include cellulose fiber (pulp fiber), polynosic rayon fiber having improved crystallinity of cellulose, polyvinyl alcohol fiber, and acrylic fiber. Among these, a crosslinked pulp fiber obtained by subjecting a wood pulp made of cellulose to a crosslinking treatment is preferable from the viewpoint of production costs.

When an absorbent is formed from hydrophilic fibers having a water centrifugation retention of more than 0.7 g / g, body fluid is absorbed by these hydrophilic fibers, and the elastic modulus of the fibers is reduced. Since the body fluid tends to remain, the humidity in the wearing environment increases due to the water vapor released from the remaining body fluid. Incidentally, chemical pulp such as ordinary softwood pulp and hardwood pulp has a centrifugal retention amount of water of about 1 to 2 g / g.
Examples of the crosslinking agent for cellulose include N-methylol compounds such as dimethylol ethylene urea and dimethylol hydroxyethylene urea; polycarboxylic acids such as tricarballylic acid citrate and butanetetracarboxylic acid; polyglycidyl ether compounds; Aldehyde compounds are preferably used.

It is necessary that the absorbent body 4 contains a highly water-absorbing polymer in addition to the non-swellable or low-swellable hydrophilic fibers described above. More specifically, it is important that the bodily fluid that has passed through the topsheet is absorbed and held by the superabsorbent polymer without remaining between fibers. Thereby, the generation of water vapor from the excreted body fluid is reduced, and it is possible to effectively prevent a rise in humidity in the wearing environment.

As the superabsorbent polymer, a polymer capable of absorbing and holding a body fluid 20 times or more its own weight and gelling is preferable. Examples include polyacrylic acid and salts thereof, and polyacrylic acid graft polymers, such as starch, cross-linked carboxymethylated cellulose, polymers of acrylic acid or alkali metal acrylates, or copolymers thereof. As the polyacrylate, a sodium salt is preferable.

The superabsorbent polymer has a function of quickly absorbing and retaining body fluid from between fibers, and the polymer surface is kept in a dry state even after absorbing and swelling the body fluid, so that it is difficult to emit vapor. It is preferable that the material does not hinder the movement of the body fluid between the polymers even after the absorption and swelling. Since such a function is difficult to be exhibited when the polymer has a uniform crosslinked structure, the superabsorbent polymer preferably has a crosslink density gradient.

As a method for imparting a crosslinking density gradient to the superabsorbent polymer, for example, when a polyacrylate is used as the superabsorbent polymer, a crosslinking agent capable of reacting with the functional group of the polyacrylate (hereinafter referred to as a “crosslinking agent”). , Polymer crosslinker)
Depending on the type, a method may be mentioned in which the polymer surface is further reacted with a polyacrylate to crosslink the polymer surfaces. As the polymer crosslinking agent, a compound having two or more functional groups capable of reacting with a carboxyl group is preferable, for example, polyglycidyl ethers such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and glycerin triglycidyl ether. And polyols such as glutaraldehyde and glyoxal, and polyamines such as ethylenediamine.

The particle form of the superabsorbent polymer is preferably non-spherical. When the particle morphology is non-spherical, it is possible to prevent a decrease in voids between polymer particles due to rearrangement and adhesion of the particles when the superabsorbent polymer absorbs body fluid and swells. As a result, gel blocking that tends to occur in the case of spherical particles can be prevented, and rapid and sufficient absorption by the polymer is performed.

As a method of obtaining a non-spherical superabsorbent polymer, a method of pulverizing a superabsorbent polymer obtained by bulk polymerization to form a non-spherical polymer, or a method of producing a superabsorbent polymer,
A method for obtaining the amorphous superabsorbent polymer comprising an agglomerated product having the polymer particles as primary particles by bonding the obtained polymer particles to each other by a contact reaction with a polymer crosslinking agent, and a polymer dispersant for producing the polymer. And a method of obtaining an amorphous polymer or the like by selecting the above.

The superabsorbent polymer is used in combination with the above-mentioned hydrophilic fiber. The mode of the combined use is particularly limited, for example, by arranging the superabsorbent polymer in an aggregate of hydrophilic fibers in a layered manner by spraying or the like. However, it is preferable that the superabsorbent polymer is three-dimensionally dispersed in the aggregate of hydrophilic fibers. When dispersed three-dimensionally, the contact area between the fiber and the superabsorbent polymer increases, and the body fluid permeated through the top sheet can be quickly absorbed by the superabsorbent polymer without stagnating between the fibers. The effect of preventing a rise in humidity is further improved. Here, “three-dimensionally dispersed” means
It does not mean that the water-absorbing polymer exists linearly or in layers between the fiber aggregates, but that the superabsorbent polymer is dispersed not only in the plane direction but also in the thickness direction between the fiber aggregates. .

Further, the superabsorbent polymer preferably has a centrifugal retention amount of 25 g or more in a physiological saline,
More preferably, it is 30 g or more. The measuring method will be described later in Examples.

The content of the hydrophilic fiber in the absorber (absorbing layer) 4 is 30 to 80% based on the total weight of the absorber.
, And particularly preferably 35 to 60%. When the content of the hydrophilic fiber is within the above range, the liquid immobilization rate of the absorbent article can be further increased, and the morphological stability and the polymer fixability of the absorber can be improved. .

The content of the superabsorbent polymer in the absorber 4 is 20 to 70 with respect to the total weight of the absorber.
%, Preferably 35 to 60%. When the content of the superabsorbent polymer is within the above range, the liquid immobilization rate of the absorbent article is high, and the surface stability and the polymer fixability due to the movement of the wearer are better than the surface. Is easy to design. The mixing ratio of the hydrophilic fiber and the superabsorbent polymer in the absorber 4 is preferably 3/7 to 9/1 by weight ratio (former / latter).

The sheet 5 has a water-repellent PET / PE.
Spunbonded nonwoven fabric made of a core-sheath composite fiber can be used. For the pressure-sensitive adhesives 7 and 8, ordinary materials used for absorbent articles can be used without any particular limitation.

In the napkin 1 of this embodiment, like the conventional sanitary napkin having a wing portion, the back sheet 3 is first fixed to the clothing such as shorts with the adhesive 7, and then the clothing is wrapped. (See the arrow R in FIG. 2) The wings 6, 6 can be bent and used by fixing the wings 6, 6 to clothing with an adhesive 8 disposed on the lower surface side thereof.

The napkin 1 has the bending rigidity El lower than the bending rigidity Ec.
In the central part, it is possible to obtain a flexible fit to the movement of the body and clothes and a good feeling of wearing. In addition, since the deflection of the central portion is suppressed, the wing portion 6 can be bent without any trouble, and there is no problem that the adhesives of the opposing wings adhere to each other. Useful for Therefore, the wing portion can be appropriately mounted on the clothes, and the napkin 1 can be mounted on the clothes without any change. Furthermore, since the absorbent sheet 41 is disposed at the center to reduce the bending rigidity Es to be lower than the bending rigidity Ec, the peripheral portion is preferentially deformed, and the central portion corresponding to the excretory portion is removed. The body can be more stably fitted and the amount of absorption at the center can be increased. In addition, since the sheet 5 is disposed so as to cover both sides of the absorber 4, even when the absorber 4 absorbs a large amount of liquid, the liquid held by the absorber 4 is
There is no leakage from the side of the napkin 1.

When the napkin 1 uses a water vapor permeable sheet as the back sheet 3, water vapor generated from the liquid absorbed by the absorber 4 is discharged out of the sanitary napkin, and when the napkin 1 is worn. Even the rise of humidity is prevented. As a result, it is needless to say that a feeling of wetting and stuffiness can be eliminated, and a comfortable feeling of wearing can be obtained.

4 (a) to 4 (d) show another embodiment of the absorbent article of the present invention. In the figure, the same reference numerals are given to parts common to the napkin 1 of the embodiment, and the description thereof will be omitted. Therefore, the description of the napkin 1 of the first embodiment is appropriately applied to the parts that are not particularly described.

The napkin 1 'shown in FIG. 4A has the same structure as the napkin 1 except that the nonwoven fabric 9 is provided between the absorbent sheet 40 and the top sheet 2. With such a configuration, the same effects as those of the napkin 1 can be obtained.

A napkin 1 'shown in FIG. 4 (b) has an absorbent body 4' composed of an absorbent sheet 40 'having an embossed groove extending in the width direction and a nonwoven fabric 9. With such a configuration, the same effect as that of the napkin 1 can be obtained, and a thinner and more flexible configuration can be realized.

The napkin 1 'shown in FIG. 4 (c) is obtained by embossing the absorbent sheet 40 of the napkin 1 and further reducing the absorbent sheet 41 to one.
It is thinner than the napkin 1 and has the same effect as the napkin 1.

The napkin 1 'shown in FIG. 4D has an absorbent sheet 4' which is not creped.
The napkin 1 has the same configuration as that of the napkin 1 except that the napkin 1 is formed only. With such a configuration, the same effect as in the napkin 1 can be obtained.

The present invention is not limited to the above-described embodiments, but may be made within the scope of the present invention.
It can be changed as appropriate.

For example, in the present invention, as in the napkin 1 of the above embodiment, it is preferable that both end portions of the absorbent sheet 40 are bent and abutted on the back sheet 3 side. It is also possible to overlap without joining (it does not join even if it overlaps), and when both ends are overlapped in this way,
The same effect as in the butted form can be obtained.

In the present invention, for example, it is preferable to use, as the absorber 4, one obtained by subjecting the above-mentioned absorbent sheet to creping at the time of its production to form wrinkles or wavy irregularities in the width direction. As shown in FIG. 5, by embossing grooves 42 extending in the width direction at predetermined intervals in the longitudinal direction on the surface of the absorbent sheet 40 'constituting the absorbent body 4', the above-described absorbent sheet is creped. The same effect as that of the napkin 1 having the configuration described above can be obtained. Further, as in the napkin of each of the above embodiments,
It is preferable that the leakage prevention groove 20 is formed by embossing and the top sheet and the absorbent sheet 40 are integrated, but the leakage prevention groove 20 can be omitted as necessary.

It goes without saying that the present invention can be applied to a sanitary napkin having no pair of wings, a sanitary napkin not having a wing, a panty liner, an incontinence pad, etc., in addition to the above-described sanitary napkin having a pair of wings on both sides. Nor.

[0055]

EXAMPLES Hereinafter, the present invention will be further described based on examples and comparative examples. In preparing the sanitary napkins of the examples and comparative examples, first, a superabsorbent polymer and absorbers A to H were prepared as described below.

<Superabsorbent polymer> 500 m provided with a stirrer, a reflux condenser, a dropping funnel and a nitrogen gas inlet tube.
l in a 4-neck round bottom flask, add 230 ml of cyclohexane
Also, 1.4 g of sorbitan monostearate (trade name: Leodol SPS-12, manufactured by Kao Corporation) was charged and stirred to form a uniform solution. Separately, in an Erlenmeyer flask,
30 g of acrylic acid monomer was neutralized with 13.4 g of caustic soda dissolved in 39 g of water to give a monomer concentration of 45%.
(55% water content) was obtained. Next, 0.1 g of potassium persulfate was added to and dissolved in the aqueous monomer solution. The obtained monomer aqueous solution was dropped into the four-necked round bottom flask charged with cyclohexane and the like under a nitrogen atmosphere, and then heated to 70 to 75 ° C. to initiate polymerization. Then, the amount of water in the polymer suspended in cyclohexane was controlled to 35% by azeotropic dehydration (cyclohexane was refluxed). Thereafter, an aqueous solution prepared by dissolving 0.03 g of ethylene glycol diglycidyl ether in 1 ml of water was added at 73 ° C., and the mixture was kept at this temperature for 2 hours. After removing cyclohexane, the obtained polymer was heated to 80 to 100 ° C. And dried under reduced pressure to obtain a superabsorbent polymer. This superabsorbent polymer has a cross-link density gradient on the surface, has an irregular particle surface, and has a centrifugal retention of 33 g / g in saline.

<Absorbent A> Fiber diameter 15 μm (2 denier)
C) sheath / core = polyethylene / polyester core / sheath composite
Alkyl phosphate and sorbitan fatty acid
A surfactant mixed one-to-one with stell is applied to the fiber
Fibers that adhere to 0.4% by weight and do not swell with water
And a basis weight of 20 g / m composed of 100% of the hydrophilic fibers.^Twoof
A suction heat bond nonwoven fabric A was produced. What is this
Separately, the equilibrium swelling absorption of water measured by the following measurement method
Wood chemical pulp with a centrifugal retention of 1.1 g / g (commodity
Name: NB-416L, Waferuser Co., Ltd.] 100 g of crosslinking agent
As dimethylol dihydroxyethylene urea
Name: Sumitex ResinNS-19, manufactured by Sumitomo Chemical Co., Ltd.]
5% by weight, metal catalyst [trade name: Sumitex Accelerator
X-110, manufactured by Sumitomo Chemical Co., Ltd.]
Dispersed in 1000 g aqueous solution
To 200% by weight of wood chemical pulp
And heat in an electric dryer at 135 ° C for 10 minutes.
Cross-linking between cellulose and intra-molecular
Lup A was obtained. Equilibrium swelling and absorption of water in the obtained crosslinked pulp A
The centrifugation retention amount after collection was 0.35 g / g. Also water
Is a hardwood whose centrifugal retention after absorption of equilibrium swelling is 1.3 g / g
Wood pulp LBKP [Product name: PRIME ALBEAT ASPEN HAND
WOOD, Waferuser Co., Ltd.]
Cross-linking treatment was carried out according to the procedure to obtain cross-linked pulp B. Obtained
The amount of centrifugal retention of the crosslinked pulp B after the equilibrium swelling of water was
It was 0.45 g / g. Crosslinked Pulp A, Crosslinked Pulp B
And polyvinyl alcohol fiber [trade name;
Do, manufactured by Sansho Co., Ltd.] at a weight ratio of 78: 20: 2.
Disperse and mix in water to form a slurry.
And then dried to yield a basis weight of 30 g / m ^TwoWet nonwoven
Cloth A was obtained. Same set as used for papermaking of this wet nonwoven fabric A
Web (dry basis weight 2)
0g / m^Two), And after the web has been wetted before drying
Superabsorbent polymer on the basis weight 30g / m^TwoAnd evenly
Sprayed and sprayed further before drying
The above-mentioned wet nonwoven fabric A was stuck on the water-absorbing polymer.
Then, it is compressed and dried to obtain a polymer sheet A in which these are integrated.
-0 was obtained. And the width of this polymer sheet A-0
Crepe processing in the direction extending in the direction
80g / m^TwoPolymer sheet A was obtained. Polymer sheet
A is 175 mm long and 75 mm wide (polymer sheet A-
1), length 80 mm, width 30 mm (Polymer sheet A-
Cut out in 2) and fold the polymer sheet A-1 in the width direction
Fold the absorbent sheet in the center of the polymer sheet A-1.
A-2 were laminated. Further, the polymer sheet A-2
Skin contact surface side of polymer sheet A-1 included in the center
And the suction heat-bonded nonwoven fabric A is 175 in length.
mm, width 55 mm, cut out and laminated to obtain absorber A
Was.

[Measurement method of centrifugation retention amount of water] <Measurement of centrifugation retention amount of hydrophilic fiber> 20 ° C., relative humidity 6
The measurement is performed as follows in a room with a constant temperature and humidity of 5%.
After accurately weighing 1 g of a fiber or hydrophilic material sample and placing the sample in a bag made of nylon mesh (250 mesh), the bag is placed in a beaker containing 500 ml of ion-exchanged water for 30 minutes. put. And a centrifuge [trade name: H-130C Kokubu Centrifuge Co., Ltd.]
The bag was rotated at 2000 revolutions / minute (895 G centrifugal acceleration) for 10 minutes. Thereafter, the sample weight was measured, and the retained absorption amount after centrifugation (centrifugation retained amount) was determined from the following equation. Fiber centrifugation retention (g / g) = (sample weight after centrifugation−initial sample weight) / initial sample weight (1 g) <Saline centrifugation retention of superabsorbent polymer> 20 ° C.
The measurement is performed as follows in a room of 65% relative humidity and constant temperature and humidity. After accurately weighing 1 g of the superabsorbent polymer and placing the sample in a bag made of nylon mesh (250 mesh), the bag is placed in a beaker containing 500 ml of physiological saline and left for 30 minutes. And a centrifuge [trade name: H-130C Kokubu Centrifuge Co., Ltd.]
The bag was spun at 2000 revolutions / minute (centrifugal acceleration of 895 G) for 10 minutes. Thereafter, the sample weight was measured, and the retained absorption amount after centrifugation (centrifugation retained amount) was determined from the following equation. Polymer centrifugation retention (g / g) = (sample weight after centrifugation−initial sample weight) / initial sample weight (1
g)

<Absorbent B> Crosslinked pulp A, crosslinked pulp B
And polyvinyl alcohol fiber [trade name;
Manufactured by Sansho Co., Ltd.] at a weight ratio of 87: 10-3.
Disperse and mix in water to form a slurry.
And then dried to obtain a basis weight of 40 g / m ^TwoWet nonwoven
Cloth B was obtained. Same set as used for papermaking of this wet nonwoven fabric B
Web (dry basis weight 3)
0g / m^Two), And after the web has been wetted before drying
The superabsorbent polymer is weighed at 60 g / m.^TwoIn average
Spray all at once and spray further before applying to the drying dryer
The wet nonwoven fabric B is laminated on the superabsorbent polymer.
And then press-dry to obtain a sheet in which these are integrated.
Was. The sheet has a wavy claw extending further in the width direction.
Processing, total basis weight 130g / m^TwoPolymer of
Sheet B was obtained. Polymer sheet B (length 175 mm,
On the same width as that used for the absorber A
Heat-bonded nonwoven fabric A (length 175 mm, width 55
mm), and the suction heat-bonded nonwoven fabric A is
Absorbent B was obtained as the surface layer side.

<Absorbent C> Basis weight 20 g /
producing suction heat-bonded nonwoven fabric of m ^2. Next, polyoxyethylene sorbitan monolaurate [ethylene oxide addition mole number 6, Kao, as a hydrophilic surfactant] in linear low density polyethylene [ethylene / 1 octene copolymer, manufactured by Mitsui Petrochemical Co., Ltd.] (Manufactured by Corporation)
Was blended by 1% by weight, and the mixture was melted and blown out (melt blown method) to obtain an average fiber diameter of 8 μm and a basis weight of 30 g / m ^2.
Was laminated on the same suction heat-bonded nonwoven fabric A as that used for the absorber A as the melt blown nonwoven fabric C. Then, the superabsorbent polymer is evenly sprayed on the meltblown nonwoven fabric C at a basis weight of 40 g / m ² , and the linear low-density polyethylene in which a hydrophilizing agent is internally added on the sprayed superabsorbent polymer A. Fiber (average fiber diameter: 8 μm) was sprayed at a basis weight of 30 g / m ² to obtain a polymer sheet C-0 having a total basis weight of 120 g / m ² . This sheet is further subjected to a corrugated embossing process in the width direction to obtain a polymer sheet C.
-1 was obtained. Separately, a linear low-density polyethylene fiber (average fiber diameter: 8 μm) into which the above-mentioned hydrophilizing agent is internally added is deposited at a ratio of 1: 1 by weight of the superabsorbent polymer until it is deposited in a net form from the melt outlet. The total basis weight is 80 g / m ² (the basis weight of the superabsorbent polymer is 40 g /
m ² ) of polymer sheet C-2 was obtained. Then, the polymer sheet C-1 was cut into dimensions of 175 mm in length and 150 mm in width, and the polymer sheet C-2 was cut to 80 m in length.
m, cut out to a width of 30 mm, polymer sheet C-
1 was folded in the width direction with the suction heat-bonded nonwoven fabric C side as the surface side, and the polymer sheet C-2 was laminated on the center of the polymer sheet C-1 to obtain an absorber C.

<Absorbent D> The same polymer sheet C-0 as used for the absorbent C was cut into a size of 175 mm in length and 150 mm in width, and the suction heat-bonded nonwoven fabric of the polymer sheet C-0 was cut in the width direction with the nonwoven fabric as the surface side. folding,
It was set as absorber D.

<Absorbent E> The polymer sheet A-0 used for the absorbent body A was cut out into two pieces with a length of 175 mm and a width of 75 mm, and two pieces were cut out with a length of 80 mm and a width of 30 mm. The same suction heat-bonded nonwoven fabric A as used in (1) was cut out and laminated at a length of 175 mm and a width of 55 mm, and an absorbent body E was obtained using this as a surface layer side.

<Absorbent F> A length of 175 mm in a direction parallel to the corrugated crepe of the polymer sheet B and a width of 75 mm in a direction perpendicular to the crepe (vertically and horizontally inverted from the absorbent B) were cut out. Then, on this sheet, a suction heat-bonded nonwoven fabric A having the same basis weight as that used for the absorber A was used for a length of 175.
The nonwoven fabric A side was taken as a surface layer side, and the absorber F was obtained.

<Absorbent G> Two sheets of the polymer sheet C-0 were cut out at a length of 175 mm and a width of 75 mm, and the suction heat-bonded nonwoven fabric side of the polymer sheet C-0 was used as an absorbent body G as a surface layer side.

<Absorbent H> Wood chemical pulp having a centrifugal retention of 1.3 g / g after equilibrium swelling and absorption of water [trade name SKEENA]
PRIME Skeena Cellulose Co. ] Was mixed was uniformly dispersed in water in water to obtain a wet absorbent paper having a basis weight of 18 g / m ² and dried after papermaking with the paper making net. This wet-type absorbent paper is cut into a size of 175 mm in length and 75 mm in width, and a super-absorbent polymer is placed thereon with a 175 mm in length and 75 mm in width.
Spread almost uniformly so that the basis weight is 60 g / m ² per mm,
Further, wood chemical pulp (trade name: NB-416L, manufactured by Waferuser Co., Ltd.) having a centrifugal retention of 1.1 g / g after equilibrium swelling and absorption of water was 175 mm long, 75 mm wide, and basis weight 1
At 00g / m ² , it is piled in the air, and the length is 175m
Absorbent H was obtained by cutting the above-mentioned wet-type absorbent paper cut out to a size of m and 75 mm in width and wrapping the above-mentioned pulp, water-absorbing polymer A, and absorbent paper and compressing and integrating them.

Using the absorbents A to H obtained as described above, the sanitary napkins of Examples 1 to 4 (see FIGS. 4A to 4D) and Comparative Examples 1 to 4 were used. It was prepared as follows.

<Example 1 (see FIG. 4A)> PET /
An opening nonwoven fabric obtained by subjecting a suction heat-bonded nonwoven fabric made of PE core-sheath conjugate fiber to a basis weight of 25 g / m ² and subjecting to an opening process with an opening ratio of 10% and one opening diameter of 0.8 mm as a top sheet 2, The top sheet 2 is placed on the absorber A (FIG.
The sheet 4) was superimposed on the reference numeral 4) in (a), and these were applied to a hot roll having an embossed pattern as shown in FIG. 3, and the top sheet 2 and the absorber 4 were integrated by heat sealing. Then, a spunbonded nonwoven fabric having a basis weight of 20 g / m ² composed of water-repellent PET / PE core-sheath conjugate fibers is double-layered on both sides as a leakproof sheet 5, and the topsheet 2 and the leakproof sheet are heated by a hot roll. The sheet 5 was integrated by heat sealing. Thereafter, hot melt is applied in a spiral shape at a width of 50 mm, a length of 150 mm, and a basis weight of 5 g / m ² on the center of the non-skin contact surface side of the absorbent body 4, and a width of 1 mm, a length of 150 mm, And applied in a bead shape at an amount of 150 g / m ² ,
The back sheet 3 made of a polyethylene sheet of 5 g / m ² was overlaid. Further, the periphery of the napkin 1 'is adhered by heat sealing, and the leak-proof sheet 5, the top sheet 2 and the back sheet 3 are integrated, and the length is 200 mm and the width is 95 mm.
mm. Then, on the non-skin contact surface side of the back sheet 3, the hot melt 7 as a shift preventing agent has a length of 150 mm.
mm, width 20 mm, basis weight 30 g / m ² , coated in two rows at predetermined intervals in the width direction, width 60 mm, length 170 mm
To obtain a sanitary napkin.

<Examples 2 to 4 and Comparative Examples 1 to 4> The sanitary napkins of Examples 2 to 4 were prepared in the same manner as in Example 1 except that absorbers B to D were used instead of absorber A. (See FIGS. 4B to 4D). Further, sanitary napkins of Comparative Examples 1 to 4 were produced in the same manner as in Example 1 except that absorbers E to H were used instead of absorber A.

[Measurement of Leak Performance (Number of Leaks Occurred)] The test samples of the prepared sanitary napkins of Examples 1 to 4 and the sanitary napkins of Comparative Examples 1 to 4 were mounted on a movable female waist model. After wearing the shorts, the model
They were allowed to walk for 10 minutes at a walking speed of 0 steps / minute. Then, while walking the model, 5 g of defibrinated horse blood (manufactured by Japan Biotest Laboratory Co., Ltd.) was injected into the tube at a rate of 4 g / min, and then the model was allowed to walk for 20 minutes.
Thereafter, 3 g of defibrillated horse blood was injected at a rate of 4 g / min while the model was walking, and the model was allowed to walk for another 20 minutes. Thereafter, 3 g of defibrillated horse blood was injected at a rate of 4 g / min while the model was walking, and the model was allowed to walk for another 20 minutes. And 5g
After walking for 20 minutes after injection, 8g After walking for 20 minutes after injection, and 11g
At each time point after 20 minutes of walking, the number of samples was 10
The number of leaked sheets among the sheets was examined.

[Measurement of Distortion Ratio] Test samples of the sanitary napkins of Examples 1 to 4 and the sanitary napkins of Comparative Examples 1 to 4 were mounted on the shorts of a movable female waist model fitted with shorts. The test sample mounting width at that time was measured as Lo. Thereafter, the model was walked at a walking speed of 100 steps / min for 10 minutes. Then, while the model was walking, 5 g of defibrillated horse blood was injected into the tube at a rate of 4 g / min, and then the model was walked for 20 minutes.
Thereafter, 3 g of defibrillated horse blood was injected at a rate of 4 g / min while the model was walking, and the model was allowed to walk for another 20 minutes. Thereafter, 3 g of defibrillated horse blood was injected at a rate of 4 g / min while the model was walking, and the model was allowed to walk for another 20 minutes. And 5g
After walking for 20 minutes after injection and at a time point after walking for 20 minutes after injection of 8 g, the shorts attached to the model were pulled down and the width of deformation of the sanitary napkin in the width direction was measured as Lx. Then, the deformation rate = the deflection rate (%) is calculated as (Lo-Lx) x 10
It was calculated as 0 / Lo.

[Thickness] A load of 2.5 gf / cm ^{2 with} a load area of 3 cm ² (disc having a radius of 9.8) was applied to the upper surface of each sanitary napkin of the example and the comparative example. It was measured by diameter.

[Measurement of Bending Rigidity of Predetermined Part] <Bending Rigidity El> The napkin in the width direction of the napkin of the example and the comparative example was sandwiched so as to include a region of at least 20% of the absorber width. The samples were taken out at an equal interval of 20 mm in the longitudinal direction. Then, using a pure bending tester (trade name; KBS-FB2, manufactured by Kato Tech Co., Ltd.), the napkin width direction is gripped by chucks at 10 mm intervals,
Pure bending was performed at a constant curvature in the range of curvature K = −2.5 to +2.5 (cm ⁻¹ ). The deformation speed is 0.50 (cm ^-1 )
/ Sec. In addition, in order to reduce the influence of gravity, the measurement was performed with the sample vertical. In the measurement, the slope of the MK curve obtained by plotting the bending moment M and the curvature K per unit length of the sample was determined, and the result was defined as the rigidity B per unit length. Then, the curvature K = 0.5 (cm ⁻¹ ) to 1.5 (c
m ^-1 ), curvature K = -0.5 (cm ^-1 ) to -1.5 (cm)
^-1 ) were measured from the characteristics in the process of increasing the absolute value of K, and these were defined as Bf and Bb. This Bf was defined as the bending rigidity when the surface layer of the napkin was bent so as to be concave. <The bending stiffness Es> Measured in the same manner as the bending stiffness El, except that the napkins of Examples and Comparative Examples were taken out from the side edges of the absorber at 20 mm in the longitudinal direction so as to include at least 20% of the width of the absorber. did. <Bending stiffness Ec> A bending stiffness Ec was obtained except that a sample was taken out at a width of 20 mm in the same manner as in the bending measurement at the center, and the longitudinal direction of the napkin was gripped by chucks at 10 mm intervals.
Measured in the same way as l.

[Evaluation of fit before and after wearing a napkin] With respect to the sanitary napkins of Examples 1 to 4 and Comparative Examples 1 to 4, each of the sanitary napkins was used for two hours each for two hours. At the above-mentioned wearing time, 20 people wore it. Then, it was judged whether or not they fit before and after, and the sensory evaluation was performed according to the following four grades (× to ◎) based on the ratio of those who supported the fit. ◎: Fits 80% or more ○: Fits slightly 50 to less than 80 △: Does not fit slightly 30 to less than 50 ×: Does not fit Less than 30%

[0074]

[Table 1]

As is clear from the results shown in Table 1, the napkins of the first to fourth embodiments (the present invention) in which the bending rigidity El is lower than the bending rigidity Ec, the bending rigidity El is not lower than the bending rigidity Ec. Compared with the napkins of Comparative Examples 1 to 4, it was confirmed that the wearability was good, that there was no uncomfortable feeling even when worn, and that twisting hardly occurred.

[0076]

According to the present invention, there is provided an absorbent article having a flexible fit to the movement of the body and clothes and a good feeling of wearing.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a sanitary napkin as one embodiment of an absorbent article according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a schematic plan view of the napkin of FIG.

4A to 4D are schematic cross-sectional views (corresponding to FIG. 2) of another embodiment of the present invention.

FIG. 5 is a schematic view showing another form of the absorbent layer in the absorbent article of the present invention, wherein (a) is a plan view and (b) is (a).
FIG. 3 is a sectional view taken along the line BB in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sanitary napkin (absorbent article) 2 Top sheet (surface layer) 20 Leak-proof groove 3 Back sheet (back layer) 4 Absorber (absorbing layer) 40, 41 Absorbent sheet 5 Sheet 6 Wing part

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) A61F 13/472 (72) Inventor Misato Hamashima 2606 Kabane-cho, Akagamachi, Haga-gun, Tochigi Prefecture F-term in Kao Corporation Research Institute 3B029 BC02 BD14 BD16 4C003 AA02 BA01 CA01 DA01 DA04 DA08 4C098 AA09 CC02 CC08 CC10 CE17

Claims (7)

[Claims] 1. A substantially vertically absorbent having a liquid-permeable surface layer, a liquid-impermeable back layer, and a liquid-retentive absorbing layer interposed between the surface layer and the back layer. In the absorbent article, the bending rigidity El when the central portion of the absorbent article is bent along the width direction so that the surface layer side is concave.
However, the absorbent article has a lower bending rigidity Ec when the central portion is bent along the longitudinal direction so that the surface layer side is concave. 2. The bending rigidity Es when the peripheral portion of the absorbent article is bent along the longitudinal direction so that the surface layer side is concave is lower than the bending rigidity Ec. 2. The absorbent article according to 1. 3. The rigidity Ec is 0.2 to 1.0 gf · cm.
The absorbent article according to claim 1 or 2, wherein the ratio is ² / cm. 4. The absorbent article according to claim 1, which has a maximum thickness of 3.5 mm or less. 5. The absorbent layer includes an absorbent sheet having both side edges bent at least on the back layer side, and the two side ends are abutted with each other or the both ends are not joined. The absorbent article according to any one of claims 1 to 3, which is arranged so as to overlap. 6. The absorbent article according to claim 1, further comprising a leak-proof groove for integrating said surface layer and said absorbing layer. 7. The absorbent article according to claim 1, further comprising a pair of wing portions fixed to clothes.