JPS6134203A - Absorbing structure for absorbing body fluids - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an absorbent structure used in disposable diapers and the like.

(Prior Art f+Fi) -IIQ In a disposable diaper, there is a liquid permeable liner on the inside closest to the wearer's skin, and a liquid impermeable cover is located on the outside of the diaper furthest from the wearer. Between the liner and the cover is a batt, which is a liquid-absorbing fibrous material.

Generally, the most economical liquid absorbent material for use in disposable diapers is cellulosic fibers such as ground wood pulp, commonly known in the art as "fluff pulp" or simply "fluff." Although batts made of such fibers have a low density and high liquid absorption capacity, their wicking capacity is very low. In contrast, the fluff contained in the high points of the diaper (when worn) remains dry when its absorbent capacity is not used. becomes.

This raises several issues.

Firstly, lining the diaper with fluff is uneconomical as most of it goes unused and wasted.Secondly, there is a risk of wetting from the central part of the diaper soaked with liquid. Additionally, this concentration of fluid in a portion of the diaper may cause discomfort to the diaper wearer.

To avoid some of these problems, U.S. Pat.
, 213.459, the prior solution is to reduce the size of the pores so that the capillary action of the pores overcomes the force of gravity and causes the exudate to move upward within the diaper. The aim is to ensure that there is enough. However, it has been noted in the past that reducing the average diameter of pores results in a decrease in the total absorbable amount. Nevertheless, in order to better distribute the liquid over the area available for liquid absorption in the diaper, this solution has been generally chosen in the past, despite the loss of liquid absorption capacity. be.

Another approach to solving such problems is taken in US Pat. No. 4,213,459.

That is, a local area of high-density fluff is provided within the batt to draw up the excretory liquid to a higher area of the diaper. Although this method is technologically advanced, it is not without drawbacks. First of all
Additionally, the surface of the diaper directly below the lining closest to the wearer's skin becomes drenched. Furthermore, the only place where liquid can move from a low density material to a high density material is at the interface where the low density material is adjacent to a high density material.

Thus, the above patent states that the portions of the bat surrounding the densified area should remain undensified.

An object of the present invention is to provide a better technique for solving such problems, as detailed below.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved absorbent structure for absorbing body fluids designed for use in absorbent pads such as diapers.

According to a first aspect of the invention, an absorbent pad or pad comprises a body-facing liquid-permeable liner having at least two layers of cellulosic fibers of different densities or average pore sizes. , a disposable diaper having an outer liquid-impermeable cover and a liquid-absorbent material therebetween, wherein the absorbent material provided by the present invention is made of cellulosic fibers having a first density or a first pore size. A first layer of cellulosic fibers is disposed below the permeable lining, and a second layer of cellulosic fibers having a higher density or smaller average pore size than the first layer is disposed below the permeable lining.
The second layer is formed substantially separate from the first layer, and the second layer is located below at least a portion of the first layer.

According to a second aspect of the invention, an extremely absorbent superabsorbent material is inserted adjacent to a dense layer of cellulosic fibers. In one preferred embodiment, the highly absorbent material is comprised of cellulosic fibers.
It is sandwiched between two dense layers, and the two layers are located below a less dense layer. In other preferred embodiments, the highly absorbent material is located beneath the second layer of cellulosic fibers.

The first form described above can be used alone or in combination with the second form described above.For objects and advantages of the invention, reference is made to the following detailed description read in conjunction with the drawings. can be fully understood.

EXAMPLES Referring to the drawings, a disposable diaper l embodying the present invention generally includes a liquid-permeable liner 2 facing the human body;
It has a liquid-impermeable cover 3 on the outside and a liquid-absorbing material, generally designated 4, between them. This liquid-absorbing material 4 has a first low density layer 5 of cellulosic fibers, such as ground wood pulp (fluff), which layer is located below the inner liner 2 . A second dense layer 6 of fluff is located below at least a portion of the first less dense layer 50 so that excretory fluid can migrate from the less dense layer 5 to the dense layer 6. Therefore, the lower surface 15 of the lower density layer 5 should contact at least a portion of the upper surface of the higher density layer 6.

However, it would not be outside the scope of the invention to place a layer of tissue paper between these N5.6.

Fluff, which is mostly softwood pulp, can be used for both layers 5.6. Alternatively, a layer of fluff consisting mostly of softwood pulp could be used for N5 and a layer of fluff consisting mostly of hard water could be used for N6, in which case the layer Between 5 and 6, the average pore size and, but not necessarily the density, vary. In this specification, "predominant"
The term "tly" means at least about 80% and the term "preponderantly" means at least about 50%.

In a first preferred embodiment shown in FIGS. 1 and 2,
The dense layer 6 is strip-shaped and extends from the target area 7, where the exudate is first collected, to the upper edge 8 of the rear side of the diaper. This high-density layer 6 allows the excretory fluid to become low-density N
from the target portion 7 of the diaper 5 toward the rear edge 8 of the diaper l. Furthermore 1. Along the upper end region 18 of the dense layer 6 towards the upper edge 8 there is surprisingly substantial fluid movement from the dense layer 6 back to the less dense layer 5. This backflow occurs from the high-density layer 6 to the low-density layer 5, but the fluid sucked by the low-density layer 5 is sufficient to satisfy the unsaturated capillary force similar to that of the high-density layer 6. In this case, the minimum pores of the low-density fibers 5 are smaller than the maximum pores of the high-density layer 6 so that the pore diameters of both layers partially match. The low-density layer 5 allows liquid to drain away from the high-density layer 6, but the low-density layer 5 does not become drenched and remains comfortable for the wearer, while the low-density layer 5 It has the advantage that most of the absorption capacity is utilized.

3 to 5 show another embodiment according to this form of the invention; in the second preferred embodiment of FIGS. 3 and 4, the dense layer 6 is in the form of strips. , extending the entire length of the diaper.

In a third preferred embodiment shown in FIG.
has the same extent as the low density layer 5.

Yet another modification of each of the above-described embodiments is to change the pore size without necessarily changing the density. −
By way of example, in place of layer 6 of high density softwood fluff fibers, at least about 50%, preferably from about 80% to 100%, of hard water fluff fibers having approximately the same density as layer 5 of low density softwood fluff fibers can be used. The inventors have found that hard water fluff of microfiber size can be utilized by using %. This is possible because the pore size of the hard water fluff is smaller than the pore size of the soft wood fluff material.

As a result, when hard water fluff fibers are used in place of high density softwood fluff fibers, two different pore size distributions are still obtained even though the densities of both layers are the same. This configuration does not depart from the scope of the invention. Thus, for example, the large-sized pore structure of the upper layer 5 resulting from a "majority" of softwood fluff pulp and the microporous structure of the lower layer 6 consisting of a "majority" of hard water fluff pulp. A two fluff sand inch having a structure compressed to a total density (preferably approximately 0.1 g/cd) produces similar results to the examples described above and is well used. be able to.

A second embodiment of the invention comprises a section of superabsorbent material (SAM) 9 as the liquid-absorbing material 4. The term "superabsorbent material" as used herein refers to one or more hydrocolloid materials that are capable of absorbing many times their weight in water or aqueous fluids.

These materials are generally prepared by polymerizing one or more monomers, which, when homopolymerized by conventional methods, result in water-soluble polymers.

To render them water-insoluble and suitable for the present invention, these polymers or polymer mixtures are typically reacted (often using crosslinking agents in this reaction) to form crosslinked polymers. This makes it water insoluble and swellable in water and water-containing fluids. Pseudo-crosslinks can also be formed by chain entanglement of high molecular weight polymers, resulting in water insolubility (e.g., U.S. Pat. No. 4,340,706
Typically, these hydrocolloids are salts of polyacrylic acid and its variants, such as methacrylic acid. Those commercially available products include WATERLOCK J-500 (trade name,
Grain Processing
ing), ABASORII 720 (trade name, Arakawa Chemical)
cal (manufactured by U, S, ^)), and Aqualic
Other superabsorbents, such as -CA (trade name, manufactured by Mitsui), include those in which starch or cellulose is the main chain, and crosslinked carboxylated cellulose is grafted with a woody polymer.

6 and 7 show a fourth preferred embodiment, in which the superabsorbent material 9 is sandwiched between a first 10 and a second 11 dense region. The first of these
The second high-density portion 10.11 is located at the same location as the high-density layer 6 in the three embodiments described above. However, it is generally preferred to position this superabsorbent material 9 in a region 17 slightly above the midpoint between the target portion 7 and the top edge 8, so that the dense layer 9 A separate reservoir for the excretory fluid sucked up by the superabsorbent material 9 is formed by this superabsorbent material 9.

An important advantage of such a form of the invention is that fluid distribution is enhanced along the length of the superabsorbent material.

In general, the superabsorbent 9 located within the fiber matrix improves fluid distribution through the thickness of the liquid-absorbing material 4. However, due to the swelling properties of the superabsorbent material 9,
According to such an embodiment of the invention, the wicking action along the entire length of the superabsorbent material 9 is significantly hindered. , this superabsorbent material 9 is placed in a first high-density section 10 and a second
This is caused by the high-density portion 11 of the area. As a result of this, the excretory liquid will come into contact with the absorbent material 9 on its upper and lower surfaces 12.13 rather than on its lower end 14. This is an improvement to the movement of excretory fluid from boundary to boundary, as in the first form of the invention described with respect to Figures 1 to 5, and the lower density layer 5 and the higher density layer 5. An improved surface-to-surface contact between 6 and 6 is achieved.

Figures 8 and 9 show another embodiment in which the superabsorbent material 9 is disposed adjacent to an outer liquid-impermeable cover and further covered with a single dense layer '6. On the other hand, this high density layer 6 is covered with a low density layer 5.

Here, (in Figures 8 and 9) layer 5 is soft wood fluff pulp, layer 6 is hard water fluff pulp (in Figures 6 and 7, layer 10 is soft wood fluff valve, and layer 11 is hard water fluff pulp). ) and
Still other embodiments can be realized by making all layers have a uniform density of about 0.1 g/c+j, or a uniform density ranging from about 0.1 g/aj to about 0.1'5 g/cd. Of course. Other variations within the scope of the invention include the use of a first Δ degree soft fluff pulp in combination with a second density hard water fluff pulp;
In this case, the second density is preferably higher than the first density.

As used herein, the term "density" refers to the density in the composite structure of the low-density layer 5 or the high-density layer 6, and does not refer to the actual fiber density.
The actual fiber density is approximately 1.5 g/Cta. ) The density of low density N5 is about 0.03 to about 0-14 g/cff
1, and a range of about 0.07 to about 0.11 g/c+d is preferred for integrity and size considerations. High density layer 6 is about 0.14 to about 0.3
g/crl, and in order to generate the desired capillary action without extra stiffness, the density should be approximately 0.1 g/crl.
A range of 6 to 0.228/c+i1 is preferred. Such a preferred range of density is the density measured under a load of 0.2 psi. An important consideration in selecting the appropriate range of densities for high-density and low-density fluff is that the pore distribution should be of two different types, one for each layer of fluff. This means that the pores should be formed so that the distribution of pores overlaps. The reason for this is that this overlap allows backflow from the dense layer to the less dense layer.

The compressed layer 6 may be a multilayer structure rather than a single layer structure, and each layer of the layer 6 may have increasing density along the width or length of the layer 6 within a specified range. It can also have a good or uniform density. The basis weight of the bottom dense layer 5 should be in the range of about 150 to 500 g/m'' to give the diaper an aesthetically pleasing shape and comfort.The basis weight of the dense layer 6 is Approximately 150
It should be within the range of 1250 g/m''.

It is preferable for the high density layer 6 to be substantially separate from the low density layer 5, rather than being formed integrally with the low density layer 5, which allows for better water distribution throughout the layer. However, even though one layer is formed on top of the other in the same machine, and some mixing occurs at their interface, layers 5 and 6 are "substantially separate." It is said that the state was formed. this"
The meaning of the term "substantially separate" is defined in U.S. Pat.
, No. 952,260, No. 2,955.641, No. 3,
No. 017,304, No. 3,060,936 and No. 3
．． Epidermis (5) as disclosed in No. 694,362 Specification 6
Rather than a substantially single layer having a kinned '5 surface), in fact, there are simply two qualitatively distinct layers formed. Therefore, compression should be uniform throughout the dense layer 6 and care should be taken to avoid substantial skinning. In this case, such skin nip is defined by the above-mentioned patent or U.S. Pat.
It is described in No. 62.

Skin nip creates an undue stiffness in the fluff, which reduces the absorbent capacity of the bonded (skinned) layer. To avoid skin nip, remove excess moisture,
Both platens may be held at approximately the same temperature to prevent condensation from forming in the thickness of the material. As a result, a void ratio of at least approximately 80% is maintained in the compressed fluff layer 6, resulting in a very high absorbent capacity.

Compression of layer 6 takes place in a hot press. Such a press may be used, for example, by Dake Laboratory Press (Model No. 44-148) by Dake of Grand Haven, Michigan, which has a thermal platen operating under suitable temperature and pressure conditions. Alternatively, a hot calender nip is preferably used for the compression process, as is known in the art.

Although ground wood pulp (fluff) is suitable for the present invention,
As other cellulose fibers, for example, cotton linters can be used. A preferred fluff is southern pine kraft wood pulp (made by sulfate treatment commonly known in the art), which is bleached;
For example, ITT Rayoneer)
or International Paper Company (I
international Paper Company
) can be purchased from. A suitable hard water fluff pulse is Southern Hard Water Kraft available from Weyerhauser as "New Bern 309".

Superabsorbent materials are available from Grain Processing Company, Muscaten, Iowa.
1Sater Lock (trade name) J-50, a product of Ain Processing Company)
0 or A-100. Suitable inner liners 2 and outer covers 3 are readily available and are well known in the art.

Of course, many changes and modifications may be made to the preferred embodiments described herein without departing from the invention. It is also possible to use co-molding (melt-blown polymer fibers mixed with wood pulp and/or stable fibers).
coformed) web, carded web, air formed (stable wood pulp mixture) web, etc.
Moreover, the absorbent structures described herein have applications beyond diapers, such as sanitary napkins and other sanitary materials.

Accordingly, the preferred embodiments described herein are intended to be illustrative and not restrictive (the scope of the invention is limited by the scope of the claims, which include all equivalents).

The advantages derived from the present invention can be fully understood from the following examples and test data.

To create high-density fluff, the fluff is passed through a hot calender nip (steel on hard rubber) at a temperature of 250°F and a speed of 304.80 fluffs/min (10 fifts/min). It was done by doing this. The nip pressure was set to a value sufficient to give a measured density of 0.15 g/cn after being left overnight. Alternatively, compaction of the fluff can be carried out in a platen press lined with blocks heated to about 250@F for about 5 seconds at a pressure sufficient to obtain the desired fluff density.

The low density fluff was created at a temperature of 250"F and a speed of 304".
This was done by passing the fluff through a hot calender nip at 80 c+m/min (10 feet/min).

The nip pressure was set to a value sufficient to give a measured density of 0.1 g/- after being left overnight.

In both cases, the fluff was made from bleached southern pine kraft wood pulp and cut to size to match the ff quantity conditions listed in Table I below. The mixed weights of the low density and high density fluff are listed in the first column of Table 1. The total weight of the absorbent is maintained at approximately 37 grams for each diaper, except for the diaper with superabsorbent. The diaper in which the superabsorbent is located as shown in FIG.
r Lock A-100, manufactured by Grain Processing Company); approximately 3 grams of polyolefin; and approximately 1 gram of porous nonwoven wrap.

This composite part was made as described in US Pat. No. 4,381,782. The structure of the diaper is formed by sandwiching the absorbent composite part between a porous non-woven polypropylene liner (23g/yd") and a polyethylene film outer cover, and sealing the outer circumference of the diaper together with adhesive. Five types of diapers were constructed by this method, corresponding to the description in Table I. Next, each diaper was subjected to a 15 minute vertical wicking test with synthetic urine. The test was carried out after 15 minutes of equilibration after being contacted with the bath.The results of this test are shown in Table 1 and Figures 10-14.

In this test, a Lucite plate (0,9525 cns
X33.02 cmX35.56 am) (3/8"
A diaper whose Ti amount had been measured in advance was placed on X13"X14"). The diaper was arranged to wrap around the edges of the plate symmetrically, and the longitudinal dimension of the diaper was parallel to the longitudinal dimension of the plate. Place the waistline edge of the diaper on the plate using masking tape and attach two elastic leg bands to facilitate this placement.
．． It was cut in 3 places.

The plate was suspended vertically over a fluid bath in a glass tray. This glass tray has the same longitudinal dimension as the diaper perpendicular to the fluid surface.

Next, the fluid was brought into contact with the lower edge of the diaper, slightly soaking the lower edge of the diaper, and this condition was maintained for 15 minutes.Then, the diaper was removed without contact with the fluid and hung in the same vertical direction. Equilibration was allowed for 15 minutes. Table I
The fluid used in the diapers listed above is synthetic urine, with a weight of 1
% urea and a weight of 1 to give a surface tension of about 56 dynes/am.
o, oi% Pluronic 10R8 surfactant and 0.04% by weight sodium azide preservative.

After equilibration, the diaper was removed from the plate, weighed, and fluid wicking recorded.

Table I summarizes the results of these measurements and displays the average of the seven measurements for each diaper.

After measuring the weight, hold the diaper horizontally and measure 7.62cmX.
Placed on a 3' x 5' cutting die.

This cutting die has a cutting edge in its width direction along with its outer edge, and is divided into nine sections, namely 4.318 ell (1, finch). With several sharp blows with a wooden mallet, the 3 inch wide absorbent strip was divided into nine sections along the longitudinal axis of the diaper. Measure the weight of each absorber in the divided parts,
After drying in the oven, it was weighed again to determine the fluid absorption Wk (Durham) per gram of fiber basis weight (corrected for solids deposited from the fluid).

In the case of diapers with superabsorbent pouches, the composition of the synthetic urine was adjusted to more closely resemble the electrolyte composition of infant urine. That is, the composition of this synthetic urine is: per liter, 0.31 grams of Ca1ls(POn)zJI
*0.0.68g KHzPOa, 0.48g (08gSO4711zO, 1.33g KISO
<, 1.24 grams of Na3PO41211*0.4.
4 grams of MacI, 3.16 grams of KCl, 0.4 grams of NaH+, 8.56 urea and 0.1 grams of Pluronic 10R8, using distilled water as the solvent. These ingredients were added in this order to 900 milliliters of distilled water, each ingredient being dissolved before adding the next and finally diluted to 1 liter.

The curve shown by the dashed line in FIG. 10 represents the equilibrium capacity of the low-density fluff at hydrostatically indicated tensile forces measured in a capillary tension cell. It is clear from this figure that only at short wicking distances (4,5C11) the fluff reaches its authorized capacity, and at large wicking heights (9-18 cm+) it is much lower than its capacity. ing.

Figures 11 to 13 show the fluid volume in the lower density fluff on the back side of the diaper and the fluid volume in the same material on the front side in the same hydrostatic head, showing the fluid wicking capacity of the compressed fluff layer against the indicated hydrostatic head. Comparison with the amount is a measure of the effectiveness of high-density fluff to improve the utilization of low-density materials (for example, in Figure 13, 2.8 g/g on the rear and 0.8 g/g on the front at hydrostatic head 18c111). 1g/g).

Figure 14 shows the effectiveness of the compressed layer in moving fluid into the superabsorbent. The amount of fluid uptake in the superabsorbent is the hydrostatic pressure head 9
12g/g in cm and 13.5C11 respectively
and 22g/g. Comparing this result with FIG. 12 shows the effectiveness of the superabsorbent in diverting fluid flow away from the fluff at the highest pressure head.

It is clear from these results that fluid distribution is greatly improved on the back side of the diaper constructed with a compressed nap layer. The contrast with the fluid distribution on the front side of the diaper, where no compressed nap layer is present, is quite clear when looking at the figures. Of course, by following the second and third preferred embodiments, better fluid distribution can be obtained on the front as well as the back side of the diaper. However, the first preferred embodiment was followed to conduct these tests for the following reason. That is, when a child is lying on their stomach with a diaper on, such as during sleep, if excretory fluid is released, the front side of the diaper tends to become completely wet.

Furthermore, these results indicate that fluid dispersion in the low-density fluff portion is important. This shows that it is possible to obtain unexpected synergistic effects in such diaper configurations.

In the case of the superabsorbent diaper made according to the fourth example described above, the superabsorbent material caused a large amount of fluid to flow from the upper portion of the diaper. However, the upper edge 8 of the diaper
These parts of the side provide extra absorbent capacity when needed.

The inventor believes that the same function as high-density fluff can be achieved with normal density (
It has been found that 0.1 g/cII of microfiber hard water pulp fluff can be obtained. This discovery is based on the density 0
．． 1. g/cnl hard water valve fluff and density 0,2 g
/ crl by observing that the porosity distribution with softwood fluff is strikingly similar. The following tables compare the vertical wicking properties of softwood moss and hard water fluff.

The vertical wicking test was somewhat similar to the test performed on all the diapers described above. This test was performed in the same direction and manner as described for diapers, with a 0.95
25alX 12.7CIlX 35,56ca+(3
/8"X5"X14") placed on a Lucite plate, 62ca
The test was carried out on the absorbent material piece No. 59). The fluff pieces were supported on a Lucite (acrylic resin) plate using a nylon mesh screen. The plates and fluff pieces are then suspended from a weight sensing means, such as a load cell on an Instron tensile testing machine, and then absorbed with synthetic urine (in these cases a secondary or saline formulation). In contact with the lower end of the body piece, the amount of fluid uptake as a function of time was recorded at several intervals for a 15 minute continuous test. Absorption amount is per unit width (2,54 am (1 inch))
It was calculated as the number of grams per 1 g/- unit tsubo. Vertical wicking capacity was defined as the amount of absorption in specified units at the end of the 15 minute test. The stated rates are measured from the pronto of absorption in basis weight per unit width and time %am for a time interval of 7-21 seconds. The test was repeated 6 times and the results reported are the average values of these 6 measurements.

Fluid dispersion measurements in this test were made by cutting the sample with a die immediately after the test was completed, and the method was the same as described for all diapers. In this case, parts corresponding to the same height position were combined and the results are shown in Table 3.

As estimated from the results in Table ■, the density is 0.1g/=j
The vertical wicking capacity of hard water fluff is density 0.2g/c
It corresponds closely to the softwood fluff ability of rA.

The initial wicking rate of hard water fluff is between the two softwood fluffs. The fluid dispersion pattern in Table 3 also shows the similarity between hard water fluff and softwood fluff with a density of 0.2 g/cffl. These results mean that the average pore diameter of the former is slightly larger than that of the latter.

Therefore, the combination of soft wood with a density of 0.1 g/cnl and hard water fluff is 27! ) has a highly concentrated fluid dispersion property for the compressed sand inch structure.

+fz 心It'11 鋒释W In this example, hard water fluff is covered with a double fluff layer made of soft wood fluff. Hard water fluff is milled kraft South American eucalyptus hardwood pulp.

After 2 WJ of fluff was compressed with zero layers containing softwood and hard water pulp layers of the same weight to a density of 0.1 g/cm3, the vertical wicking properties were:

Comparing the liquid dispersion results of the two-layer fluff in Table IV with those of the softwood kraft (Table ■), the presence of the eucalyptus layer shows that the upper two hydrostatic stamps (i.e.
It becomes clear that the fluid wicking for 13.5 cm and 18 cm) is significantly improved. This is very unique considering that eucalyptus exhibits only 50% of the bilayer structure.

Soushi ■ 40ft 1% super absorbent material (laterlock J-
500, manufactured by Guillein Processing Company)
40 g of melt-blown polypropylene containing
A web of I1g was prepared. The superabsorbent is treated with sufficient surfactant (e.g., about 0.3-0.5 percent Trit
onX-102) Rohm & Hass Company (
Rohm & Haas Company) with a surface area of approximately 1 m+”/g to ensure wetting of the fiber matrix, and the composite material Compressed to /-.

Using this web, the vertical wicking test described in Example (2) was conducted and the results shown in Table V were obtained.

From these results, the vertical rise of the fluid is 4,5
cm, but it is clear that it essentially stops there. The reason for this is believed to be that the expanding particles became lodged within the pores, thereby restricting fluid flow within the web.

This same web was used in diapers with a density of 0.2 g/
A vertical wicking test (as described in Example I) was performed on the entire diaper by placing it under the soft fluff of the superabsorbent, and the effectiveness of the fluff layer as a fluid dispersion member of the superabsorbent was revealed. Table 1 shows the fluid dispersion for the entire absorbent composite, the fluff layer itself and the meltblown/superabsorbent web.

Comparing the vertical dispersion of the melt-blown/superabsorbent web taken from diapers (Table ■) with the data in Table ■, the action of the fluff causes the fluid to be wicked higher, improving the dispersion for the superabsorbent ( Weight: 11.6g/9cm height
Compare g and 1.1 g/g; also 1 3.5 cr
Compare the values of 2.7 g/g and 0.1 g/g at n height), where both tests were conducted in open mode for a period of 15 minutes.

Furthermore, as these tests continue, the wicking height of the diaper continues to increase, but the wicking of the superabsorbent web alone virtually ceases.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a first preferred embodiment of the invention without superabsorbent material. FIG. 2 is a cross-sectional view taken along line 2--2 in FIG. 1. Figure 3 shows the second embodiment of the present invention which is not provided with superabsorbent material.
FIG. 2 is a perspective view of a preferred embodiment of the invention. FIG. 4 is a longitudinal sectional view taken along line 4--4 in FIG. 3. FIG. 5 is a partially cutaway perspective view of a third preferred embodiment of the invention without superabsorbent material. FIG. 6 is a perspective view of a fourth preferred embodiment of the invention with a section of superabsorbent material. 7 is a longitudinal sectional view taken along line 7-7 in FIG. 6. FIG. FIG. 8 is a perspective view of a fifth preferred embodiment of the invention with a section of superabsorbent material. FIG. 9 is a longitudinal cross-sectional view taken along line 9-9 vA of FIG. FIG. 1θ is a diagram showing the absorbency distribution of the prepared diaper tested in Example 1. FIG. 11 is a diagram showing the absorbency distribution of a diaper having one layer of compressed fluff in addition to the standard fluff described in Example 1. In addition to the standard fluff portion described in Example 1, FIG.
FIG. 3 is a diagram showing the absorbency distribution of a diaper having compressed fluff. FIG. 13 is a diagram showing the absorbency distribution of a diaper having three layers of compressed fluff in addition to the standard fluff described in Example 1. FIG. 14 shows the absorbency distribution of a diaper having two layers of compressed fluff and a portion of superabsorbent material as described in Example 1. l...diaper, 2...liner, 3...cover,
4... Liquid absorbing material, 5... First layer, 6... Second layer, 7... Target portion, 8... Top edge, 9...
Superabsorbent material, 10.11...high density part. FIG, 1 FIG, 3 FIG, 5 FIG, 6 FIG, 7 FIG, 8

Claims (1)

[Claims] 1) A disposable diaper having a liquid-permeable liner facing the human body, an outer liquid-impermeable cover, and a liquid-absorbing material located therebetween, wherein the liquid-absorbing material is: a first layer of cellulosic fibers having a first density disposed under a permeable lining of; and at least a portion of the first layer of cellulosic fibers having a density lower than the first density; 1. An absorbent structure for absorbing body fluids, comprising a second layer made of cellulose fibers and having a second density that is substantially higher than the first layer. 2) An absorbent structure according to claim 1, having a portion made of superabsorbent material disposed adjacent to the second layer made of cellulosic fibers, the surface of the superabsorbent material being An absorbent structure characterized in that the absorbent structure is brought into contact with the surface of the second layer. 3) Absorbent structure according to claim 1, characterized in that it has a portion of superabsorbent material in contact with the underside of the second layer of cellulosic fibers. 4) The absorbent structure according to claim 1, wherein the first density is about 0.03 g/cm^3 to about 0.14 g/cm^3.
An absorbent structure characterized in that the absorbent structure is between g/cm^3. 5) In the absorbent structure according to claim 1, the second layer has a density of about 0.14 g/cm^3 to 0.3
An absorbent structure characterized in that the absorbent structure is between g/cm^3. 6) The absorbent structure according to claim 1, wherein the first layer has a density of about 0.03 g/cm^3 to about 0.03 g/cm^3.
14g/cm^3, and the density of the second layer is approximately 0.
An absorbent structure characterized in that the absorbing structure has an absorption density between 14 g/cm^3 and 0.3 g/cm^3. 7) The absorbent structure according to claim 1, wherein the first density is about 0.07 g/cm^3 to about 0.11 g/cm^3.
An absorbent structure characterized in that the absorption structure is between g/cm^3. 8) In the absorbent structure according to claim 1, the second density is about 0.16 g/cm^3 to about 0.22 g/cm^3.
An absorbent structure characterized in that the absorption structure is between g/cm^3. 9) In the absorbent structure according to claim 1, the first density is about 0.07 g/cm^3 to 0.11 g.
/cm^3, and the second density is 0.16g/cm
Absorbent structure characterized in that it is between ^3 and 0.22 g/cm^3. 10) The absorbent structure of claim 1, wherein the second layer has a porosity of at least about 80%. 11) In a disposable diaper having a body-facing liquid-permeable liner, an outer liquid-impermeable cover, and a liquid-absorbing material located therebetween, the liquid-absorbing material is: beneath the inner permeable lining. a first layer of cellulosic fibers having a first density disposed on; a second density disposed in contact with at least a portion of the first layer of cellulosic fibers that is greater than the first density; a second layer of cellulosic fibers formed substantially separately from the first layer; and a superabsorbent material disposed in contact with at least a portion of the second layer. 1. An absorbent structure for absorbing body fluids, characterized in that it has a portion. 12) An absorbent structure according to claim 11, wherein a second absorbent structure comprising a superabsorbent material and cellulosic fibers is provided.
Absorbent structure characterized in that it has a third layer of cellulosic fibers disposed below the layer and having the same density as the second layer. 13) The absorbent structure of claim 11, wherein the second layer has a porosity of at least about 80%. 14) In a disposable diaper having a body-facing liquid-permeable liner, an outer liquid-impermeable cover, and a liquid-absorbing material located therebetween, the liquid-absorbing material is: below the inner permeable lining. a first layer of cellulosic fibers having a first average pore size disposed in the cellulosic fibers; An absorbent structure for absorbing body fluids, comprising a second layer made of cellulose fibers having a second average pore diameter and formed substantially separate from the first layer. 15) An absorbent structure according to claim 14, comprising a portion of superabsorbent material disposed adjacent to the second layer of cellulosic fibers, the surface of the superabsorbent material being An absorbent structure characterized in that the absorbent structure is brought into contact with the surface of the second layer. 16) Absorbent structure according to claim 14, characterized in that it has a portion of superabsorbent material placed in contact with the underside of the second layer of cellulosic fibers. 17) In the absorbent structure according to claim 14, the first layer is mostly made of soft wood fluff, and the second layer is made of soft wood fluff.
The absorbent structure is characterized in that the majority of the layer is hardwood fluff. 18) The absorbent structure of claim 17, wherein the first and second layers both have a density of about 0.1 g/c.
An absorbent structure characterized in that m^3.