Fluid absorbing sheet, method of making same and disposable product incorporating such absorbing sheet

The present invention relates to an absorbent sheet for a disposable absorbent article.

Absorption sheets used in diapers, urinary incontinence articles and the like should have the ability to quickly absorb and retain fluids secreted from the body, which are released in significant amounts in a relatively short time. To meet this goal, the absorbent sheet should have the ability to quickly capture the outflowing fluid, to prevent leakage of the fluid beyond the edges of the sheet, absorb, spread the fluid through wick action and retain fluid within all available absorption volume and enclose the absorbed fluid to avoid damage caused by leaks and secondary wetting.

The absorbent sheet, which has been found to be particularly advantageous in this respect, is a combination of a highly permeable fluid transfer layer, such as pulp, having an extremely short liquid penetration time and having a high absorption capacity and a laminated absorbent material tank made of, for example, a sphagnum material connected in a way that ensures accurate fluid movement with the fluid transfer layer, to permanently retain absorbed fluid. This composite absorption sheet combines the desired features of rapid fluid penetration, high absorption capacity and excellent tamponing capability, which is reflected in a reduced leakage rate.

In order to further increase the fluid absorption properties of the composite absorption sheet, a laminate collecting body equipped with a liquid distribution well located in the inner layer of the body is used. In the present specification, the terms "inner layer and" outer layer define different layers of the laminate body accumulating depending on their location relative to the fluid-carrying layer. The inner layer is located closer to the fluid transfer layer, and the outer layer is further away from the liquid transfer layer. The well plays a twofold role. First, it reveals the outer layer relative to the fluid-carrying layer through an opening in the inner layer, thereby increasing the surface area of ​​the laminate tank capable of absorbing fluid. Secondly, the well has the ability to distribute fluid passing through the fluid transfer layer along the laminate tank from the impact site, and prevents local supersaturation and leakage due to excess fluid overflowing.

Despite the fact that the absorption sheets of the type described above exhibit relatively good performance, it is desirable to further improve their fluid absorption capacity.

Absorbent sheet for a disposable absorbent article according to the invention comprising a highly absorbing fluid transfer layer with low fluid retention capacity and a laminate collecting body connected to the transfer layer and having an inner layer disposed on the side of the transfer layer and an outer layer, wherein the inner layer is shaped the fluid distribution well, characterized by that a porous, hydrophyte spacer is arranged between the inner layer and the outer layer of the laminate collecting body, which is an extension of the fluid distribution well between the inner and outer layers, and is connected through the well to the transfer layer.

Preferably, the porous hydrophyte spacer has a density in the range of about 0.005 to 0.08 g / cm3.

Preferably, the porous hydrophyte spacer has a density in the range of about 0.01 to 0.04 g / cm3.

Preferably, the porous hydrophyte spacer has a density in the range of about 0.01 to 0.02 g / cm3.

Preferably, the thickness of the porous, hydrophyte spacer is in the dry state, when measured under a pressure of 2.8 g / cm2, from about 0.025 cm to about 1.27 cm.

Preferably, the thickness of the porous, hydrophyte spacer is in the dry state, when measured under a pressure of 2.8 g / cm², from about 0.076 cm to 0.762 cm.

Preferably, the thickness of the porous, hydrophyte spacer is in the dry state, when measured under a pressure of 2.8 g / cm2, from about 0.127 to about 0.635 cm.

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Preferably, the laminate collecting body is in the form of a C-folded sheet.

Preferably, the inner layer and outer layer are separate sheets.

Preferably, the inner layer consists of two strips spaced apart from each other, between which a well is formed.

Preferably, the porous hydrophilic spacer is a uniform sheet.

Preferably, the porous, hydrophilic spacer is a pair of strips spaced apart on each side of the fluid distribution well.

Preferably, the transfer layer comprises fluff pulp.

Preferably, the laminate collecting body comprises composite sphagnum material.

Preferably, the porous, hydrophilic spacer comprises a material selected from the group consisting of fluffed wood pulp, a composite fabric of disordered polyester and two-component wetting agent treated fibers, cellulose foam with open pores, material with high content of filling fibers, cross-linked cellulose pulp, mixtures heat-resistant synthetic pulp and mixtures thereof.

Preferably, the well is an opening in the inner layer.

It has been found that if a highly porous and hydrophilic element is placed between the inner and outer layers of the laminate collecting body, a significant improvement in the fluid absorption properties is achieved by reducing the liquid penetration time in the laminate body. The highly porous and hydrophilic element is actually transparent to the fluid in motion, while at the same time forming a spacer between the absorbent layers of the laminate collecting body, allowing fluid to flow into the fluid distribution well and fluid to flow deeply into the absorption layers. The resultant increase in the effective absorption surface of the laminate body contributes to the reduction of fluid absorption time.

In contrast, the known absorbent sheet that does not have such a porous and hydrophyte element between the absorbent layers of the laminate body is characterized by a slower fluid penetration rate because the absorption layers adhere exactly to each other and the fluid cannot penetrate between them.

The absorbent sheet of the invention is well suited for use in disposable absorbent products, such as disposable adult briefs, diapers, pads for involuntary soaking, menstrual pads, wound dressings, bandages and the like.

The subject of the invention is illustrated in the embodiments of the drawing, in which fig. 1 is a perspective view of disposable briefs for adults with the absorbent sheet according to the invention, fig. 2 - a perspective view in section of the briefs of fig. 1 along line 2-2 in fig. 1 , Fig. 3 - enlarged cross-sectional view of the disposable adult briefs shown in Fig. 1, Fig. 4 - perspective view of the laminate absorption body of the absorbent sheet in the first embodiment, Fig. 5 - perspective view of the laminate absorption body of the absorbent sheet in the second embodiment, Fig. 6 - perspective view of the system for testing the determination of fluid penetration time in the absorption sheet.

The absorbent article for single use in the form of panties 10 for adults shown in Figures 1, 2 and 3 is equipped with an absorbent sheet 16 according to the invention. The pants 10 have an impermeable backing layer 12, a highly permeable cover layer 14 and an absorbent sheet 16 sandwiched between the backing layers 12 and the cover 14. The absorbent sheet 16 comprises a non-absorbent transfer layer 118, evenly distributed along the backing layers 12 and the cover 14 except for their side parts. Underneath the transfer layer 18 in the absorbent sheet 16 is a laminate collecting body 20 containing a uniform C-shaped composite absorbent material sheet having superimposed inner and outer layers 22.

The inner layer 22 consists of transversely bent parts of a single absorption sheet whose edges are spaced apart. Between them is formed a fluid distribution well 26 located along the entire length of the laminate collecting body 20.

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Between the inner and outer layers 24 a relatively thin sheet of highly porous and hydrophilic material is placed forming the spacer 27, separating the inner layer 22 and the outer layer 24 from each other and defining between the aaA and the

ŁLWłl l * ŁVHXV k> II nmi mliii jnviy ³ćn nnHAŻ j «- z yŁVJvi puwn., Within the laminate collecting body 20, between inner layers 22 and outer 24.

The laminate collecting body 20 is covered with a thin and highly fluid-permeable wadding 28, to increase its integrity, structural and durability, without adversely affecting the fluid absorption process. Wadding 28 prevents the absorbent material of the laminate collecting body 20 from disintegrating or tearing under the influence of mechanical stresses arising during the automatic folding of disposable underpants 10 for adults or when the disposable underpants 10 are used in wet or dry condition. In the most preferred embodiment, the wadding 28 is nonwoven.

In the first variant, shown in Fig. 4, the inner layer of the laminate collecting body 20 is physically separated from the outer layer and is formed by a pair of belts 30, 32, spaced apart and defining a liquid distribution well 26 between them. In this version, wadding 28 forms an internal structural coating that holds together all the components of the laminate collecting body 20.

In the second variant, shown in Fig. 5, the highly porous and hydrophilic layer of the spacer is formed by two separate belts 27a and 27b, extending on each side of the fluid distribution well 26.

The process of liquid absorption by the composite absorption sheet 16 according to the invention takes place as follows:

The fluid that flows into the absorbing surface of the disposable adult briefs 10 flows freely through the fluid-permeable cover layer 14 and penetrates the transfer layer 18. Due to the highly porous structure, the fluid penetration rate in the transfer layer 18 is high, which reduces the possibility of fluid leakage the edges of briefs 10 due to damage to the transfer layer 18 upon rapid retention of the released liquid. For applications in cases where the rate of fluid release is rapid and high, the ability of the composite absorption sheet 16 to absorb fluid upon contact is particularly important, significantly reducing the likelihood of damage. Urinary incontinence is an example of a situation in which the attack of fluid secreted by the body can only be stopped by an absorption structure that exhibits an ultra-short absorption time. A highly porous fibrous network has been found to be particularly advantageous in this respect, since the released fluid can be easily and quickly absorbed due to the large distances between the fibers of the network.

Although the transfer layer 18 has the ability to quickly absorb fluid, it is unable to maintain absorbed fluid within a network of distant fibers. In the event that the transfer layer 18 is below the saturation level, the fluid migrates from the transfer layer 18 towards the laminate collecting body 20 under the influence of capillary action, due to the significant suction force between them. Such fluid migration is slow and well controlled and proceeds at the rate of fluid take-up through the laminate collecting body 20.

In the event that fluid leaks onto the transfer layer 18, the controlled migration process is disturbed because the mass of fluid released onto the composite absorption sheet 16 penetrates through the transfer layer 18 and collects on the laminate collecting body 20. The liquid distribution well 26 serves as a temporary fluid holding system to prevent leaks from spilling as the liquid disperses along the laminate collecting body 20, distributing the liquid to a larger absorption surface, which accelerates the process of fluid penetration into the laminate collecting body 20.

The highly porous and hydrophyte spacer layer 27 significantly increases the ability of the fluid distribution well 26 to hold and disperse fluid due to the increase in the capacity of the well 26 and the increase in the absorption surface through which it passes

169 866 the process of collecting fluid into the laminate collecting body 20. In contrast to known composite absorption sheets in which the fluid dispensing well 26 is small, the present invention gives a much larger well 26, reaching deep between the inner and outer layers 24, enabling more efficient use available liquid absorbing surface, thereby reducing the time of liquid penetration into the laminated tank 20.

The invention is illustrated by the following examples. These examples are not intended to limit the scope of the present invention, but taken together with the above detailed and general description, they enable a better understanding of the essence of the present invention. A description of the various experimental procedures to which the absorbent sheets of the following examples were subjected is given in Table 1.

Example 1. A known absorbent sheet with a laminate collecting body was tested, without a fluid distribution well in the inner layer and without a spacer between the layers.

Covering layer:

Basis weight (g / m²):

Density (g / cm³):

Total weight (g): Dimensions (cm):

Fluid transfer layer: Basis weight (g / m2):

Density (g / cm3):

Total weight (g): Dimensions (cm):

Laminate collecting body:

One layer weight (g / m2):

Density (g / cm3):

Total weight (g): Dimensions (cm):

Undercoat layer:

Non-woven with Enka fibers (fibers commercially supplied by BASF Company)

0,02

L2

12,7X38,1

Two layers of softened wood pulp 130 (on wassew)

0,05

12.5

12,7X38,1

Two superimposed layers. complex sphagnum material

425

0,2

41.5

12,7X38,1

Polyethylene foil.

Example II A known composite absorption sheet with a C-shaped laminate collection body without spacer was tested.

Covering layer 14: Fibrous with Enka fibers (fibers supplied for trading by BASF Company)

Weight (g / m2): 25

Density (g / cm3): 0.22

Total weight (g): 1.2

Dimensions (cm): 12.7 X 3,, 1

Fluid transfer layer 13: Two layers r <^: ^ {^ uk ^ l ^ nR ^ r ^ <^ g ^

Weight (g / m2): 130 ^ a wa ^ w))

Density (g / cm3): 0.05

Total weight (g): 12.5

Dimensions (cm): 12.7 X 3.3.1

Laminate collecting body 20: A complex Sorfovy layer folded in the shape of the letter C with a liquid distribution well 2.5 cm wide in the inner layer.

Weight per layer (g / m2): 425

Density (g / cm3): 0.2

Total weight (g): 337.0

Dimensions (cm): 22.9 X 38, 1

Undercoat H: Polystyrene foam.

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EXAMPLE III. The absorbent sheet of the invention was constructed in a manner

<td>shown in Figures 1, 2 and 3. Covering layer 14:</td><td>Non-woven with Enka fibers (fibers supplied</td>

<td>Basis weight (g / m²): Density (g / cm³): Total weight (g): Dimensions (cm): Fluid transfer layer 18:</td><td>for trading by BASF Company) 25 0.02 AT 12.7 X 38.1 A single layer of loose wall</td>

<td>Weight (g / m2): Density (g / cm3): Total weight (g): Dimensions (cm):</td><td>wood 130 0.05 © 6 12.7X37 X</td>

Laminate collecting body 20: A complex peat layer bent into shape

<td></td><td>letter C, with a well 26 distributing liquid 2.5 cm wide in the inner layer 22.</td>

<td>One layer weight (g / m2): Density (g / cm³): Total weight (g): Dimensions (cm): Spacer 27:</td><td>425 © 0 37.0 22,2X38J A single layer of loose fluff</td>

<td>Weight (g / m2): Density (g / cm³): Total weight (g): Dimensions (cm): Undercoat layer 12:</td><td>wood 130 0,025 6.6 12,7X383 Polyethylene foil.</td>

Example IV The absorbent sheet according to the invention was tested.

<td>Covering layer 14:</td><td>Non-woven fabric with Enka fiber (fibers fed in</td>

<td>Weight (g / n ©): Density (g / cm3): Total weight (g): Dimensions (cm): Fluid transfer layer 18:</td><td>for trading by BASF Company) 25 0,022 1.2 12,1X384 A single layer of dissolved 3. ^^</td>

<td>Weight (g / m2): Density (g / cm3): Total weight (g): Dimensions (cm):</td><td>wood ł.30 0,025 6.6 12.7X37 X</td>

Laminate collection body 20: A composite layer of sphagnum agifa

<td>One layer weight (g / m2): Density (g / cm ^): Total weight (g). Dimensions (cm): Spacer 27a, 27b:</td><td>letter C, with a well 26 distributing liquid 2.5 cm wide in the inner layer 22 P 2 O 5 © 0 π N, v © 22,9X38 Two strips 27a, 27b spread apart at a distance from one layer of fluffed wood pulp on both sides of the fluid distribution well 26</td>

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Weight (g / m2): 130

Density (g / cm³): 0,05

Weight of each strap (g): 5.5

Dimensions of each strap (cm): 5.1 X 38.1

Undercoat layer 12: Polyethylene film.

Example V. Absorption sheet according to the invention constructed as shown in Figures 1, 2 and 3.

Covering layer 14: Non-woven fabric with Enka fibers (fibers supplied by BASF Company)

Weight (g / m2): 25

Density (g / cm3): 0.02

Total weight (g): 12 ^

Dimensions (cm): 12.7 X 38.1

Fluid transfer layer 18: A single layer of softened wood pulp

Weight (g / m2):

Density (g / cm3):

Total weight (g):

Dimensions (cm):

Laminate collecting body 20:

Basis weight (g / m2): Density (g / cm³):

Total weight (g):

Dimensions (cm):

Spacer 27:

130

0,05

6,2

12.7 X 38.1

A complex oorphic layer folded into the shape of the letter C, with a well 26 distributing liquid 2.5 cm wide in the inner layer 22 425

0,2

37,0

22,9X38,1

Stripped woven fabric of disordered polyester / 6 dpf (denier per fiber) and bicomponent (3.8 dpf) in a ratio of 75:25, sprayed with 0.10% GR-5 solution (trademark) of a wetting agent manufactured by Rohm and Haas Company, USA.

Weight (g / m2): Density (g / cm³): Total weight (g): Dimensions (cm):

Undercoat layer 14:

0)115

1,5

22.7X88.1 Polyethylene film.

The composite absorption sheets according to examples I-VI were tested for:

a) fluid penetration time

b) fluid movement within the laminated tank; and

c) free surface humidity.

The results of completed tests are summarized in Table 1.

Table 1

<td></td><td>Example AND</td><td>Example 11</td><td>Example III</td><td>Example IV</td><td>Example V</td><td>Example VI</td>

<td>Fluid penetration time (sec)</td><td> 36</td><td> 25</td><td> 22,5</td><td> 27</td><td> 11</td><td> 32</td>

<td>Fluid movement in laminate body (cm)</td><td> 33</td><td> 33</td><td> 34,6</td><td> 35,6</td><td> 36,3</td><td> 35,6</td>

<td>Free surface humidity (%)</td><td> 165</td><td> 170</td><td> 135</td><td> 130</td><td> 130</td><td> 130</td>

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Description of the test procedure.

The basis weight of the absorbent material was determined by weighing a 0.09 m sample²and converting its weight to a square meter (g / m2) of its surface.

The density of the absorbent material was determined by determining the weight of the 5.1 x 7.6 cm sample and dividing it by the sample volume (surface thickness X). For material of loose fluff, the thickness of the sample is measured under a pressure of 2.8 g / cm2.

The fluid penetration time for the absorbent material was determined by measuring the time needed to completely absorb a finite amount of fluid.

The test of time required for the liquid to be absorbed by the sample at a pressure of 2.8 g / cm2, covered with a plexiglass plate, was made as shown in Fig. 6, measuring the absorption time of 5.45cm³/ g of sample liquid supplied to the sample through an oval hole on a 9x13 centimeter plate. The permeation time was recorded when all free liquid had disappeared from the surface of the sample visible in the oval hole.

A 1% NaCl solution was used as the test fluid.

Fluid displacement in the laminate collecting body was determined to determine the ability of the absorbent material to disperse fluid within its structure by measuring the distance the finite amount of fluid deposited on the absorbent material had traveled. For this purpose, 5.45 cm3 / g of test fluid was introduced into the sample based on the weight of the absorbent material sample. The distance traveled by the fluid from the delivery point was recorded after 15 minutes. A 1% NaCl solution was used as the test fluid.

The humidity of the free surface at the fluid supply site was tested to determine the ability of the absorbent material to draw fluid into the structure. For this purpose, NuGauze (the trade name of Johnson Johnson Inc.) was placed under the cover layer of the composite absorbent sheet and under a 50g load, 15 minutes after the outflow of 5.45cm3 / g test liquid, based on the weight of the absorbent material used on the absorbent sheet. The fluid intake of the sponge is measured as a percentage of its dry weight. The measurement result of the fluid taken is expressed as the amount of fluid remaining at the point where the fluid reaches the absorbent sheet. A 1% NaCl solution was used as the test fluid.

By comparing the fluid permeation times shown in Table 1 for known absorption sheets according to Examples I and II, it can be seen that the configuration of the laminate collecting body significantly affects its absorption properties. Placing the fluid dispensing tune in the inner layer results in a significant reduction in fluid penetration time.

A significant improvement in the fluid penetration time compared to these known absorption sheets is achieved by using a low density, high porosity and hydrophilic spacer layer between the layers of the laminated tank. The density of the spacer is particularly important and has a great impact on the penetration time of the fluid. The best results are obtained when using the absorbent sheet according to example V, which has the lowest density spacer layer. In Example 6, an increase in the density of the spacer layer has an adverse effect on fluid penetration time. An absorption sheet constructed in accordance with Example 6 does not have to have practical applications due to its inferior properties; it serves only the purpose of illustrating the relationship between the density of the spacer layer and the fluid penetration time.

In addition to improving the fluid penetration time, the use of a spacer also promotes faster drying of the place where the fluid is released, as evidenced by the results of the determination of the free surface humidity at the place of fluid supply and the results of the determination of fluid movement inside the layer of the laminate collecting body.

The scope of the present invention is not limited by the description, examples and proposed uses, and modifications can be made without departing from the spirit of the present invention.

The absorbent sheet of the present invention can also be used in various absorbent articles, such as disposable incontinence pads, adult panties, diapers, menstrual pads, or tampons or as a means

169 866 dehumidifiers intended for use in dressing materials to keep goods dry during sea transport or storage. The use of the absorbent sheet of the present invention for hygiene purposes and other healthcare applications may include any known methods and techniques for maintaining incontinence hygiene and for medical and absorption purposes. The invention includes modifications and changes insofar as they fall within the scope of the appended claims.

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